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Kinetic and microstructural aspects of the aqueous alteration of glass

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Kinetic and microstructural aspects of the aqueous alteration of glass
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Zoitos, Bruce K., 1960-
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ix, 162 leaves : ill., photos ; 29 cm.

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Brines ( jstor )
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Groundwater ( jstor )
Kinetics ( jstor )
Leaching ( jstor )
Nuclear waste ( jstor )
pH ( jstor )
Sodium ( jstor )
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Thesis (Ph. D.)--University of Florida, 1992.
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Includes bibliographical references (leaves 151-161)
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Typescript.
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Vita.
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by Bruce K. Zoitos.

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KINETIC AND MICROSTRUCTURAL ASPECTS OF
THE AQUEOUS ALTERATION OF GLASS














BY

BRUCE K. ZOITOS


A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN
PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF DOCTOR OF PHILOSOPHY


UNIVERSITY OF FLORIDA

1992


UNIVERSITY OF FLORIDA LIRAIES






























Copyright 1992

by

Bruce K. Zoitos






























For Mom and Dad, of course.

But mostly, for me.













ACKNOWLEDGEMENTS


I wish to thank my advisor, Professor David Clark, for introducing me to the field

of glass corrosion and for the many growth opportunities he made available to me during

my graduate school career. I also thank Professors Stan Bates, Emmett Bolch, Robert

DeHoff, Alex Lodding and E. Dow Whitney for their guidance and participation as

committee members.

I am very grateful to those individuals whose time and expertise contributed

materially to this work. Guy Latorre provided numerous hours of assistance with both

ICP and FTIRRS studies. I thank Professor Lodding and his staff at Chalmers University

of Technology for countless SIMS profiles and for helping to meet those ever-present

publication deadlines. Professor J.F. Quinson of Universite Claude Bernard was very

generous to provide porosimetric analysis using his "one-of-a-kind" calorimeter. Dr.

David Hensley of the Ceramic Engineering Department at Rutgers University performed

the XPS measurements discussed in this work. A very special thanks goes to Dr. Steve

Spooner of the National Center for Small Angle Scattering Research at Oak Ridge

National Laboratory for giving up several evenings to insure that my samples were

completed within the allotted 48 hours beam time. Thanks go also to Richard Crockett,

Augusto Morrone and Andy Duncan for expert TEM and SEM work.








None of this would have been possible without the financial support of

Westinghouse Savannah River Company and its predecessor, E.I. du Pont de Nemours

and Company, nor would it have been possible without the enthusiasm and personal

support of Dr. George Wicks of WSRC. I am endebted to George for his friendship and

encouragement. It is with much pleasure that I thank Drs. Phil Bennett and Vince Puglisi

of Gates Energy Products for tolerating the periodic absence of a certain GEP scientist

during the busier stages of this work.

Finally, I wish to thank all my friends and fellow students for providing the love

and moral support that helped me to stay afloat during some very difficult and painful

times. You are too numerous to mention, and I trust you will not be offended if your

names are omitted. You know who you are. I would like to extend very special thanks

to Beree Darby, who was a sympathetic listener at a time when I needed someone to

listen and Anne Ricker, whose friendship has been a reassuring constant for the last two

years. Lastly, I wish to thank my former supervisor, Bob Stosky, for a particular

conversation in December 1990, in which I was reminded of my true reason for coming

to graduate school. That conversation resulted in the appearance of this dissertation

approximately one year later.













TABLE OF CONTENTS


ACKNOWLEDGEMENTS............................................................................. iv

A B STRA CT....................................................................................................... viii

CHAPTERS

1 INTRODUCTION........................................................................................... 1

2 OVERVIEW OF AQUEOUS CORROSION IN SILICATE GLASSES......... 4

Reactions of Amorphous Silica with Water............................... ....... 5
Solubility of Amorphous Silica at 250C......................................... 5
Effect of Temperature on the Solubility of Amorphous Silica...... 5
Effect of pH on the Solubility of Amorphous Silica................... 7
Effect of Particle Size on the Solubility of Amorphous Silica...... 7
Kinetics of Silica Dissolution and Deposition................................ 9
Structure and Corrosion of Alkali-Silicate Glasses.................................. 10
The Structure of Alkali-Silicate Glasses.................................. 12
Corrosion of Alkali-Silicate Glasses........................... ........... 14
Corrosion of Commercially Important Ternary Glasses.......................... 16
Corrosion of Soda-Lime-Silica Glass.............................................. 17
Corrosion of Sodium Borosilicate Glass.................................... 18
Corrosion of Nuclear Waste Glasses..................................................... 23
Characteristics of Nuclear Waste Glass Alteration Layers............ 24
The Savannah River Leachability Model................................... 26
The Thermodynamic Model....................................................... 29
Geochemical Modelling of Glass Corrosion................................. 30

3 OBJECTIVES AND ACCOMPLISHMENTS........................................................ 34

4 STRUCTURAL, MICROSTRUCTURAL AND KINETIC ASPECTS
OF CORROSION IN BINARY ALKALI-SILICATE GLASSES........... 36

Experimental.................................................... ..................................... 36
R esults.......... .............. ............................................................................ 42
Visual Inspection.............................................................. ............. 42








Scanning Electron Microscopy.................................... ........... 42
Transmission Electron Microscopy................................................. 61
Small Angle Neutron Scattering................................. .......... 66
BET Gas Adsorption Analysis................................... ........... 71
Fourier Transform Infrared Reflection Spectroscopy................ 74
X-ray Photoelectron Spectroscopy.............................. .......... 78
Leachate Analysis.................................................................... 80
Surface/Bulk Solution Studies..................................... .......... 87
Summary, Model and Discussion................... ................................ 90
Corrosion of Li20.2SiO2.......................................................... 90
Corrosion of Na20-2SiO,......................................................... 92
Corrosion of K20-2SiO2.......................................................... 95
A Model for Corrosion in Binary Alkali-Silicate Glasses......... 95

5 AQUEOUS ALTERATION OF
165/TDS SIMULATED NUCLEAR WASTE GLASS............................ 98

Introduction...................................................... .................................... 98
Experim ental........................................................................................... 99
Glass Processing and Composition............................. .......... 99
Leachants................................................... ............................... 99
Leach T ests ....................................................................................... 10 1
Field Leaching Studies..................................................................... 104
R esults.................................................................................................... 105
Scanning Electron Microscopy....................................................... 105
Transmission Electron Microscopy............................................ 113
Therm oporom etry............................................................................. 113
Fourier Transform Infrared Reflection Spectroscopy................... 118
Secondary Ion Mass Spectrometry................................................. 121
Leaching K inetics............................................................................. 134
Sum m ary and D iscussion............................................................................. 138
Corrosion of 165/TDS in Deionized Water................................... 143
Corrosion of 165/TDS in Granitic Groundwater............................ 144
Corrosion of 165/TDS in WIPP-A Brine........................................ 144
Correlation of Laboratory and Field Studies................................. 145

6 CONCLUSIONS AND SUGGESTIONS FOR FUTURE WORK.................... 147

C onclusions.................................................................................................. 147
Future W ork........................................................................................... 149

REFEREN CES................................................................................................... 151

BIOGRAPHICAL SKETCH.................................................................................... 162













Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy

KINETIC AND MICROSTRUCTURAL ASPECTS OF
THE AQUEOUS ALTERATION OF GLASS

By

Bruce K. Zoitos

May 1992

Chairman: David E. Clark
Major Department: Materials Science and Engineering

The effect of aqueous alteration was examined in R20-2SiO2 glasses, where R

represents Li, Na or K. Glasses were leached at 700C in flowing deionized water for

periods ranging from five minutes to 40 days. Leached surfaces were examined visually

and by scanning electron microscopy (SEM), transmission electron microscopy (TEM),

Brunauer-Emmett-Teller nitrogen adsorption analysis (BET), small angle neutron

scattering (SANS), Fourier transform infrared reflection spectroscopy (FTIRRS) and x-ray

photoelectron spectroscopy (XPS). Leaching kinetics were evaluated by inductively

coupled plasma spectroscopy (ICP) analysis of leachate solutions.

Drastically different alteration surfaces and kinetics were observed for each glass.

Depending upon the glass, surface layers were composed of the original silica network,

a porous colloidal silica precipitate or were completely absent. Leaching kinetics ranged

from diffusion-limited to linear.








A model was developed to explain these differences, based on the solution

chemistry of the hydrodynamic boundary layer adjacent to the glass surface and its effect

on glass alteration. Model predictions were validated by direct measurement of solution

parameters within this boundary layer.

A similar methodology was used to evaluate alteration product formation in a

simulated nuclear waste glass leached at 900C in deionized water and in granitic

groundwater and synthetic brine, which are considered to be "repository-relevant"

leachants. Corrosion in deionized water and granitic groundwater leads to a porous,

precipitate-like alteration product. Kinetic measurements indicate that this product serves

to decrease the alteration rate of the underlying glass. In brine, a thin brine precipitate

layer forms on the glass surface which appears to drastically reduce the corrosion rate of

the glass.













CHAPTER 1
INTRODUCTION




At the time of this writing, nearly 1.3 billion Curies (4.4 x 10'9 Becquerel) of

defense high level radioactive waste (HLW), mostly in liquid form, await processing at

four U.S. sites [Wic92]. The first U.S. HLW vitrification plant, the Defense Waste

Processing Facility (DWPF), is scheduled to begin operation this year at Savannah River

Site using an optimized glass composition designated 165/TDS. One of the primary

design targets for this glass was that it have a low aqueous corrosion rate.

Glass is the material of choice for most applications which require chemical

durability. It is inexpensive, raw materials are readily available in large quantities, it is

easily manufactured and its composition may be tailored to suit a given application. By

far, the most critical application of a glass product is that of HLW immobilization. Such

use requires a product capable of maintaining its integrity for several hundred thousand

years under "worst case scenario" conditions. The need to understand glass performance

in such an application has motivated most glass corrosion research over the last two

decades.

Prior to interest in nuclear waste glasses, most investigations of durability were

directed at simpler glasses, mostly the alkali-silicates and soda-lime-silica glasses. This

early work was somewhat limited, in that comparatively primitive analytical techniques

1








2

were available at that time. In addition, much of the work done on simple glass systems

during the 1970s was based on static test methods. In a static test, glass corrodes in a

solution in which dissolved glass components accumulate over time. As a result,

corrosion effects due to intrinsic glass behavior and effects due to the accumulation of

leached glass components in solution cannot be unambiguously determined. As analytical

methods improved during the 1980s and research emphasis shifted to more complex

nuclear waste glasses, few efforts were made to correlate the advancing waste glass

corrosion database with that of simpler, more easily understood glasses. These limitations

in understanding corrosion in simple glass systems have led to a general lack of

consensus on corrosion mechanisms in more complicated glasses.

The primary objective of this dissertation was to address deficiencies in

understanding of glass corrosion through improved studies on binary alkali-silicate

glasses. These studies introduce two innovations to this subject. First, corrosion tests

were designed to limit any effects due to accumulation of leach products in solution. This

was accomplished by leaching glasses in a flowing leachant. Additional test

modifications were made which allowed direct measurement of concentration gradients

between bulk solution and solution adjacent to the glass surface. The existence of such

gradients has long been speculated but has never been verified.

In addition, an effort was made to identify and utilize new analytical methods for

alteration product characterization. This led to a collaboration with workers at the

National Center for Small Angle Scattering Studies at Oak Ridge National Laboratory to

study leached glass microstructure using small-angle neutron scattering techniques, as well








3

as extensive utilization of in-house analytical expertise such as scanning and transmission

electron microscopy. Where possible, these techniques were applied to nuclear waste

glasses in addition to the binary glasses. In some cases, additional techniques were

utilized to circumvent analytical problems inherent to nuclear waste glasses. For example,

complex alteration product compositional profiles were measured quantitatively and to a

high degree of accuracy using secondary ion mass spectrometry techniques developed by

co-workers at Chalmers University of Technology. Thermoporometry, conducted in

collaboration with workers at Universite Claude Bernard in Villeurbanne, France, provided

pore size analysis on very limited amounts of leached nuclear waste glass and did not

require that the sample be dried. The success of these efforts was made possible not only

by utilization of advanced techniques and equipment but also by the expertise and

experience of the individuals who developed and apply them.

Analysis of the information developed over the course of this study demonstrates

that aqueous corrosion can lead to drastically different leaching kinetics and alteration

products depending upon glass composition. These diverse behaviors have been unified

by considering the effect of the inherent glass leach rate on solution chemistry.

Specifically, it suggested that interaction of the glass with the chemistry of the solution

adjacent to the glass surface is the factor which determines the mode in which the glass

reacts.














CHAPTER 2
OVERVIEW OF AQUEOUS CORROSION
IN SILICATE GLASSES



Silicate glasses encompass a family of materials with a wide range of chemical

durability. Within the silicate glasses, composition and leaching conditions exert a strong

influence on durability and corrosion. For instance, specimens of K20-2SiO2 placed in

deionized water at 700C dissolve completely within minutes, while nuclear waste glasses

corrode to only 10 15 .tm depth after two years under aggressive laboratory conditions.

While some aspects of glass corrosion are well understood, an all-encompassing

explanation of corrosion in these materials does not currently exist. Instead, several basic

mechanistic phenomena (ion exchange and network dissolution) have been described and

used to explain aspects of the corrosion process, and several models thermodynamicc,

geochemical, surface layer effects) have been proposed to explain and predict corrosion.

Thus, considerable information has been accumulated regarding atomic-level aspects of

alteration as well as global behavior of glass-water systems. Very little information exists

regarding the microstructure of glass ateration products.

The objective of this chapter is to examine previous work conducted on corrosion

in silicate glasses. For purposes of clarity, these glasses will be considered in order of

complexity: amorphous silica, alkali-silicate glasses, commercially important ternary

glasses and multicomponent nuclear waste glasses.

4










Reactions of Amorphous Silica with Water


The fundamental reaction between silica and water, as described by Eiler [Eil74],

is

(SiO2)x + 21H20 < (SiO2)x,- + Si(OH)4 (2-1)

The net reaction direction is dictated by conditions such as solubility (supersaturated or

undersaturated), temperature, pH, and silica particle size. The effect of each of these

parameters will be discussed.


Solubility of Amorphous Silica at 250C


In assessing the solubility of silica at 250C, Morey et al. [Mor64] noted that

solubility was a strong function of particle size, state of hydration and adsorbed impurities

and that several months were typically required for the silica-water system to reach

equilibrium. After allowing initial concentration transients to subside, a saturation value

of 115 ppm SiO2 was noted for dissolved silica in contact with silica gel. A similar value

was obtained by the same authors by extrapolating to 250C solubility data taken at higher

temperatures by other authors.


Effect of Temperature on the Solubility of Amorphous Silica


The work of Okamoto et al. [Oko57], Lehner and Merril [Lenl7], Elmer and

Nordberg [Elm58], Alexander et al. [Ale54], Krauskopf [Kra56], Kitahara [Kit60], and

White [Whi56] on the solubility of amorphous silica at elevated temperatures was

compiled by Morey et al. [Mor64]. The results are shown in Figure 2-1. While these
































E
ax
a.

0

2(

























Figure 2-1.


60
TEMPERATURE C


The solubility of amorphous silica in water between 00 and 1000C.
Adapted from Morey [Mor64]. Reprinted by permission of Journal of
Geophysical Research.








7

data show considerable spread, it is clear that silica solubility increases from between 75

and 150 ppm SiO2 at 250C to between 300 and 400 ppm at 900C.


Effect of pH on the Solubility of Amorphous Silica


Alexander et al. [Ale54] found that the solubility of silica was approximately

constant from pH 1 to 8; however, solubility increased rapidly above pH 8. Using

colorimetric methods, they were able to determine that the increase in dissolved silica

above pH 8 was due to the presence in solution of the H3SiO4 ion in addition to Si(OH)4.

They concluded that the reaction

Si(OH)4 + OH- (HO)3SiO- +H20 (2-2)

dictated silica solubility at high pH, with the stipulation of constant Si(OH)4

concentration. Silica solubility as a function of pH is shown in Figure 2-2.


Effect of Particle Size on the Solubility of Amorphous Silica


Since silica occurs in a number of forms, from monolithic pieces to nanometer-

sized colloids, it is important to understand the effect of particle size on solubility. In

general, convex surfaces have a higher solubility, while concave surfaces have a lower

solubility. This effect, known as the Gibbs-Thompson effect, is described by the

Ostwald-Freundlich Equation

2Ev
(2-3)
S(r)=S,e, ( )


where S(r) is the solubility of a particle of radius r, S, is the solubility of a flat surface,




















0.5




0.1

0.05


0.02

S0.01

0.005




0.001


2 4 6 8 10 12
pH.


Solubility of silica in water at 250C as a function of pH. Adapted from
Alexander et al. [Ale541. Reprinted by permission of the American
Chemical Society.


Figure 2-2.







9
E is the interfacial energy, V is the molar volume, R is the universal gas constant and T

is the absolute temperature.

For collections of small particles, points of particle-particle contact represent

regions of high negative curvature and will be preferred sites for deposition. Similarly,

small particles will dissolve due to their high radius of curvature and silica will deposit

at regions of negative curvature or on particles with larger radii, a phenomenon referred

to as Ostwald ripening.


Kinetics of Silica Dissolution and Deposition


Rimstidt and Barnes [Rim80] derived a general rate equation for the hydration and

dehydration of silica described in equation (2-1). Their work was based on the

assumption that reactants must form an activated complex of arbitrary composition as an

intermediate step during their conversion to products. Starting with the reactions

Si02 + 2H20 <- (SiO2-2H20)* (2-4)

(SiO2-2H20)* <-> Si(OH)4 (2-5)

and assuming that reaction rate is proportional to the concentration of the activated

complex (denoted with an asterisk) they derived the following rate equation

(as(o), A / 2 (2-6)
I ----- I [1 = -- towi)n kt4casmoran o- asion)


where a, is activity of i, P is the pressure, T is the absolute temperature, A is the

interfacial area, M is the mass of water in system, yi is the activity coefficient of i, k, is

the dissolution rate constant and k is the precipitation rate constant. The parameters k+







10

and k. were determined by measuring silica reaction rates at various temperatures and are

expressed as


logk_ =-0.707- 2598 (2-7)
T


logk = -0.369-(7.890 x10-4)T-343 (2-8)
T


This set of equations expresses the observation that the rate of dissolution decreases as

the activity of dissolved silica silicicc acid) increases in solution. Dissolution rate also

is proportional to the ratio of silica surface area to solution mass. Thus, a high surface

area silica submerged in a limited amount of water will reach equilibrium more quickly

than a low surface area silica in a large solution volume. The area-to-mass ratio,

commonly expressed in glass corrosion literature as the surface area-to-solution volume

ratio (SA/V), is a critical parameter which dictates kinetics and sometimes corrosion

mechanisms. Important factors and their effect on silica-water reaction rates are presented

in Table 2-1.


Structure and Corrosion of Alkali-Silicate Glasses


Next we consider the slightly more complex case of silica doped with a modifying

group I alkali oxide, R20, where R = Li, Na, K. Introduction of alkali atoms into the

glass results in a decrease in the glass transition temperature and the aqueous durability

of the glass. These effects are related to the alteration of the atomic-level structure of

silica by the conversion of bridging oxygen, or siloxane (Si-O-Si) bonds, to non-bridging









Table 2-1. Factors that Influence the Rate
of Silica-Water Reactions


Variable Effect on Reaction Rate Valid Extrapolation Range


Temperature


Exponential dependence


Pressure


Very little effect


0- 3000C

0 500 bars


Extent of System



Activity of H2SiO4





Mechanism




Silica phase present


Rate proportional to A,
inversely proportional to
M

Rate proportional to (1-
Q/K). (Q = activity
product, K = equilibrium
constant for formation of
activated complex

Rate controlled by
breaking Si-O bonds



Determines K and
therefore Q/K


No effect


Salts


Reduce aH20 and thus
SiO2 solubility

Small particles have
higher solubility


Particle size


(A/M) < 104



At large Q/K high free
energy phases may
nucleate



At low (A/M) nucleation
controls precipitation rate;
at T > 3000C diffusion
may control rates

Valid for quartz,
cristobalite and
amorphous silica

Slightly acid to neutral
systems

(?) No evidence of effect
on mechanism

For particles < 0.1 lim, K
should be corrected for
surface free energy


Adapted from Rimstidt and Barnes [Rim80].







12

oxygen bonds (NBO), which are more susceptible to aqueous attack. In addressing the

issue of corrosion, the situation is now complicated by the effect of leached alkali ions

on solution composition and pH, as well as possible barrier effects of any silicious

material remaining behind on the glass surface. The problem now becomes that of

considering a non-equilibrium solid having a constantly changing surface composition

reacting with a solution of constantly changing pH and composition. The following two

sections will discuss the structure of binary alkali glasses as a function of composition

and examine leaching data and models which have been used to explain corrosion

mechanisms.


The Structure of Alkali Silicate Glasses


The basic structural unit of silica is the SiO2 tetrahedron. Tetrahedra are joined

at their covers through bridging oxygen atoms (siloxane or Si-O-Si bonds). In order to

accommodate the introduction of R20, siloxane bonds are broken, the oxygen from R20

bonds to Si, and R' atoms take up positions to charge compensate Si-O groups. Such

bonds are referred to as non-bridging oxygen bonds. In a study using magic angle

spinning nuclear magnetic resonance, Maekawa et al. [Mae91] measured the occurrence

of bridging and non-bridging oxygen in R20-SiO2 glasses for compositions between 20

and 56 mol% R20. Their results, summarized in Figure 2-3, express glass structure in

terms of Qn groups, where n designates the number of bridging oxygens per Si04

tetrahedron. The important point of this work is that binary glasses should


























S 40 \ /
40 -4'



20 \


0
20 30 40 50
M20/mol%











Figure 2-3. Experimentally determined Qn distributions in lithium (triangles), sodium
(squares) and potassium (circles) silicate glasses as a function of
composition. Adapted from Maekawa et al. [Mae91]. Reprinted by
permission of Elsevier Science Publishers.







14

be considered a mixture of Q, groups, rather than being comprised of only one or two

types of Q groups.


Corrosion of Alkali-Silicate Glasses


Many of the studies performed on the leaching of alkali-silicate glasses were

conducted in the early 1960s, before much of the current arsenal of analytical equipment

was available. As a result, most of the data developed on corrosion of these glasses is

based on the analysis of leachate solutions.

Charles [Cha58] and Budd [Bud61 ] described the corrosion of alkali-silicate glass

by water in terms of three reactions. The first reaction is essentially an ion exchange

process in which a proton, produced by dissociation of a water molecule, replaces an

alkali atom in the glass

=Si-O-'R + H20 =Si-OH + R+ + OH (2-9)

Hydronium or a hydrogen ion could serve as the reacting species rather than water.

Another possible reaction involves the attack by OH on bridging oxygen bonds

=Si-O-Si= + OH -- =Si-OH + -Si-O (2-10)

The terminal O group created here is very reactive and may further interact with water

=Si-O- + H20 -- =Si-OH + OH (2-11)

As this reaction continues, Si may be progressively hydrated and removed from the glass

network, forming silicic acid.







15
It is also possible for terminal silanol (=Si-OH) groups to undergo condensation

to form siloxane bonds [Eil74]

=Si-OH + HO-Si- =-Si-O-Si= + H20 (2-12)

These reactions form much of the current basis of understanding of glass

corrosion. With this understanding of the reactions involved, Rana and Douglas

[Ran61a,b] produced what is considered the definitive work on the kinetics of alkali-

silicate corrosion.

Their study consisted of corroding crushed binary and ternary glass compositions

in a soxhlet extraction system in such a way that the glass was in contact with nearly pure

distilled water. Their analysis considered only the rate of appearance of glass constituents

in the leachate solution over the duration of the experiment.

In all cases, they observed two distinct leaching patterns. In the early stages of

leaching, the cumulative leached amounts of glass constituents increased with a t0-5

dependence. This was designated Stage I leaching. At later times, leaching showed a

linear time dependence, which was termed Stage II leaching.

Mathematically, Stage I was expressed as


Q(t)=a+kvt (2-13)

and Stage II was written


Q(t)=b+ct (2-14)

where Q(t) is the total amount of a given element released up to time t, a and b are

adjustable parameters, and k and c are rate constants.








16

Based on these results, they proposed a model in which alkali diffused out of the

glass by ion exchange, creating a silica-rich surface layer. Since this was a diffusional

process, a t0'5 dependence would be expected. However, the silica surface layer also is

subject to dissolution, and as the alkali removal rate is reduced due to the growing silica-

rich surface layer, a steady state is ultimately reached where both silica dissolution and

alkali removal proceed at the same rate.


Corrosion of Commercially Important Ternary Glasses


The binary glasses discussed previously are of generally low durability and of little

commerical importance. However, addition of a third component to these compositions

may drastically improve durability. The addition of approximately 10% CaO results in

a composition known as soda-lime-silica glass, which is the basis for most window and

container glass. Addition of 10%-30% B203 results in alkali borosilicate glass. Known

as Pyrex, this extremely durable glass is used in laboratory and household applications

where resistance to aqueous corrosion is required. Alkali borosilicate glasses owe their

corrosion resistance in part to phase separation, in which an easily corroded sodium borate

phase separates from a more durable silica-rich phase. Leaching of these glasses is

entirely dependent upon the distribution of the soluble phase. If this phase occurs in a

non-interconnected fashion, the corrosion properties of the glass will be dictated by those

of the silica-rich phase, as is the case with Pyrex; however, if the leachable phase

develops as an interconnected network, then it is entirely available for corrosion. In this

case, leaching will result in a porous, silica rich skeleton. This is the basis for the Vycor








17

process which is used to manufacture nearly pure silica glasses at temperatures well

below the melting point of silica [Kin76].


Corrosion of Soda-Lime-Silica Glass


In early studies of soda-lime-silica glasses, Rana and Douglas [Ran61a,b] observed

that as SiO2 was replaced by CaO in sodium-silicate glass, the glass became more durable

and the proportion of alkali to silica in the leachate approached their ratio in the glass,

suggesting that the corrosion mechanism had changed from one of selective removal of

alkali to one of congruent dissolution. Leached surfaces of this glass were still shiny and

showed no visual indications of alteration.

Soda-lime-silica glass leaching as a function of solution pH was studied by El-

Shamy et al. [E1S72] and by Smets and Tholen [Sme85]. El-Shamy et al. found that

below pH 9 no silica was extracted and alkali extraction was independent of pH; however,

at pH values greater than 9, silica extraction increased while alkali extraction decreased.

In all cases extraction of calcium was negligible. At pH values less than 3, glasses with

greater than 10 mol% CaO demonstrated a much greater dissolution rate and calcium was

observed in the leachate. At these low pH values the ratio of extracted sodium to calcium

was the same as that in the glass.

Smets and Tholen [Sme85] examined the corrosion of 20Na20 10CaO-70SiO2 in

buffered solutions at pH values from 4.5-13. Secondary ion mass spectrometry (SIMS)

analysis of the leached glasses indicated that calcium depletion was limited to the first 10

nm of the glass surface. Sodium depletion was deepest in acidic solutions (approximately







18
700 nm after 16 hours) and only 100 and 10 nm in solutions of pH 9.1 and 13,

respectively. Their results are compiled in Table 2-2. These results suggest that between

pH 4.5 and 9, corrosion is a combination of congruent dissolution (linear rate) and

diffusion-controlled leaching of alkali ions. At pH 13, the glass is leached almost

congruently, but very slowly.

A SIMS profile of a leached soda-lime-silica glass surface is shown in Figure 2-4.

This result, obtained from a 10CaO-16Na0-74SiO2 glass [Ric84], shows a surface

depleted in Na, enriched in Si and a near-surface depletion of Ca with an enrichment of

Ca at deeper levels. This result is consistent with those obtained by other workers

[Cla76a, Sme85, Gos78].


Corrosion of Sodium Borosilicate Glass


Probably the most definitive work to date on the corrosion of sodium borosilicate

glass was performed by Bunker et al. [Bun88] who used Raman spectroscopy and nuclear

magnetic resonance spectroscopy (NMR) to characterize atomic-level structure in several

sodium borosilicate glasses before and after leaching at pH 1, 9 and 12.

Raman spectroscopy of Na2O-B203.SiO2 glasses with component ratios of

30-10-60, 20-20-60 and 10-30-60 revealed significantly fewer non-bridging oxygen bonds

than would be predicted if all sodium were associated with NBO sites, indicating that

some sodium is associated with anionic, tetrahedral boron sites. In the 30-10-60 and

20-20-60 glasses Raman spectra indicated that borate structures were interspersed

throughout a silicate matrix, as evidenced by the presence of Si-O-B bonds. However,


















Table 2-2. Dissolution Rates and Sodium Depletion Depths
for Soda-Lime-Silica Glass


Buffer pH Dissolution Sodium Depletion
Rate (nm/hr) Depth (nm)



H20 5.8- 6.1 <10 720 (16hr)

KH2PO4 4.7 5.0 <10 670 (16hr)

K2HPO4 9.1 8.8 155 100 (16hr)

KOH 13.0 12.8 240 10 (Ihr)

Adapted from Smets and Tholen [Sme85].
















1110

23Na+





8Si+


I / sp --------B




0 100 200 x/nm










Figure 2-4. SIMS profile of 16Na20l10CaO.74SiO2 leached 30 minutes at 850C.
Adapted from Richter et al. [Ric84]. Reprinted by permission of
Revista Stazione Sperimentale della Vitro.







21
in the borate rich 10-30-60 glass no Si-O-B signal was detected. This suggests that the

glass is phase-separated and that borate groups tend to occur in borate rather than silicate

environments.

After the glasses were leached at pH 1 no non-bridging oxygen sites were found,

and the glasses contained substantially fewer silanol groups than would be predicted by

the conversion of NBO sites to silanols. This was taken to indicate that silanol

condensation had taken place. The leached material was nearly identical in composition

to silica, but differed from vitreous silica in that it was comprised of four-fold rings in

contrast to vitreous silica where higher order rings predominate.

For 10-30-60 glass leached at pH 9 and 12, Raman spectra were identical to that

of vitreous silica. A small proportion of Si-OH was found, and no 3- or 4-fold rings were

noted. The structure was composed of higher-order silica rings. Raman spectra of

30-10-60 and 20-20-60 glasses were unaffected by leaching at pH 9 and 12.

Nuclear magnetic resonance spectroscopy of 29Si is capable of distinguishing the

local environment of silicon in terms of the number of bridging oxygen bonds (i.e. Q4,

Q3, Q2 and Q' groups). In 30-10-60 glass prior to leaching, 75% of Si was present in Q3

groups and 25% in Q4 groups. After leaching at pH 1, 75% of Si existed in Q4 groups,

20% in Q3 groups and 5% in Q2 groups. The Q3 and Q2 groups terminated in silanol

groups rather than sodium, corroborating the results of Raman spectroscopy regarding

silanol condensation. No changes were noted in the glasses leached at pH 9 and 12 based

on NMR.







22

Acid leaching of 20-20-60 and 10-30-60 doubled the number of Q3 sites from 15%

NBO present initially to 30% silanols following leaching. In 10-30-60 glass leached at

pH 9 and 12, only Q4 sites were present after leaching.

Bunker's group also examined the amount of 170 incorporated into silanol and

siloxane bonds from leaching in H2170 labelled water. They found that '70 was

incorporated into Si-O-Si sites for all acid-leached glasses except 10-30-60, indicating

silanol condensation. The 30-10-60 glass leached at pH 12 was the only sample in which

NBO sites contained labelled oxygen and also had the lowest amount of 170 in Si-O-Si

sites. Analysis by 23Na NMR indicated that for all compositions studied, leaching at pH

1 resulted in the removal of all Na from the glass, while leaching at pH 9 and 12 did not

affect the sodium content.

Transmission electron microscopy of leached material showed that the leached

glass was comprised of a network of particles ranging in size from 10 to 160 A in

diameter. Leaching under acidic conditions favored formation of small particles, while

basic conditions resulted in larger particles. BET surface areas ranged from 350 400

m2/g with pore diameters of <30 A.

Bunker et al. concluded that the formation of silanol groups promoted the

hydrolysis of adjacent siloxane bonds, which resulted in the depolymerization and

dissolution of the silicate network. Simultaneously, silanol groups condensed, reforming

Si-O-Si bonds and repolymerizing the silica network, resulting in a leached layer similar

to colloidal silica. This behavior was used to rationalize the transition from t.05 to t'







23

kinetics described by Rana and Douglas [Ran61a,b] as the result of a leached layer which

evolved with time from being protective into being nonprotective.


Corrosion of Nuclear Waste Glasses


Assessing the mechanisms of corrosion in nuclear waste glasses presents a

substantial technical challenge. These glasses were designed to optimize multiple

properties simultaneously [Wic85a, Sop83]. They must be sufficiently durable to

immobilize radioactive waste for several hundred thousand years and be remotely

processed at temperatures sufficiently low to prevent evaporation of easily volatilized

components such as cesium. They must be insensitive to variations in waste stream

composition, be thermally stable against devitrification and have good mechanical

integrity. Glasses suitable for such applications contain numerous elements. The

composition of choice of U.S. defense waste applications, 165/TDS, contains 15 different

oxide components. The complexity of this material precludes most types of structural

analysis such as those described previously. However, an extensive empirical database

has been established for the corrosion performance of nuclear waste glass in both

laboratory and field environments [Tac90, Bra90, Sas90, Lod90, Ram90]. Significant

progress was made in the early 1980s by the Department of Energy-sponsored Leaching

Mechanisms Program [Men84] in elucidating general principles of corrosion in these

complex materials and delineating major characteristics of glass alteration layers. During

the last decade, three models have emerged which are capable of explaining and

predicting aspects of corrosion in nuclear waste glasses. These are the Savannah River







24
leachability model and the thermodynamic model, both developed at Savannah River

Laboratory, and the geochemical model, developed at the Hahn-Meitner Institut in Berlin.


Characteristics of Nuclear Waste Glass Alteration Layers


The Leaching Mechanisms Program, an intensive, multi-investigator research effort

[Men84], examined layer formation under a variety of leaching conditions. They

determined that altered glass tended to form highly structured, multi-layer structures

which had a sharp interface with the underlying glass. The alteration product retained the

dimensions of the parent glass but was of lower density. The degree of porosity varied

as a function of glass and leaching conditions, but all layers tended to have a honeycomb-

shaped surface structure. Frequently, both crystalline and amorphous structures were

found at the surface. Layer compositions were depleted in soluble elements such as Na,

B and Li but retained the less soluble elements Si, Fe, Al, Mn, Ni, Ca and Mg.

These observations were combined into the surface layer schematic shown in

Figure 2-5. This diagram shows three layers typically seen in altered nuclear waste glass.

The reaction zone at the boundary between the main layer and the unaltered glass is

typically less than a micron thick and represents the advance of aqueous attack into the

glass. The main alteration layer is found beyond the reaction zone and may be several

microns thick. The precipitate layer is at the outer surface and consists of both

amorphous and crystalline deposits. More recent work [Lod89, Abr90] supports and


















H2Si03


(H20H+)
^--\1


Crystalline (Li-Saponite,
Precipitates \Magnesite, CaC03)
Amorphous
Precipitate

Gel
Reaction
Zone
(Structured
Amorphous
Region)

Bulk Glass

Glass Reaction Zone
in Soluble Elements,
(B, Na, Li)


Figure 2-5. Schematic of alteration layer on a nuclear waste glass showing the reaction
zone, gel layer and precipitate layer. Adapted from Mendel [Men84].







26

extends the observation of layering. As many as six distinct layers have been observed

in some cases.


The Savannah River Leachability Model


The Savannah River model, also known as the Wallace-Wicks model [Wal83,

Wic92], describes the effect on glass leach rate of a growing, semipermiable precipitate

layer on the glass surface. It is assumed that the glass leaches initially by an

interdiffusional process, followed by matrix dissolution. In addition to these reactions,

the SR model considers a third process--precipitation. As glass components are released

to solution, they may saturate and precipitate onto the glass surface, forming a barrier

which may or may not have a protective effect.

The model assumes steady-state conditions and that the rate of silica dissolution

at the glass-precipitate interface, RdiS, is equivalent to the rate of diffusion of silica

through the precipitated layer, Rdif. Mathematically,


R= K(C, -C) (2-15)



Rd (CoC) (2-16)


where K is a rate constant, D is the diffusion coefficient of silica in the precipitated layer,

1 is the thickness of the precipitate layer and C, C0, and C, are the silica concentrations

in the bulk leachate, the leachate within the layer immediately adjacent to the gel layer,

and a saturated solution, respectively.







27
If L is the amount of silica leached up to time t and q is an appropriate constant,

then 1 = qL and, since R = dL/dt, the above equations may be rearranged to yield



dL_ KC C (2-17)
dt I-pL

where p = Kq/D represents the silica dissolution from the glass and C/C, represents the

degree of saturation of silica in the system.

If the system is closed then leaching products accumulate in solution and C/C, =

aL, where a = SA/V(1/C,), SA is the glass surface area and V is solution volume.

Integrating 2-17 using the conditions that at t = 0, L = 0 the result is


(1+ +)O(n(l-aL))+1L=-aKCt (2-18)


In the case that the system is open and leach products do not accumulate then as V --> ,

a -> 0 and


L+ 2=KCSf (2-19)


These results are summarized in Figure 2-6 which plots the slope of a log-log plot

of silica release vs. time against the log of the reaction extent. Curve A shows that in the

early stages of leaching the slope is unity (congruent dissolution) and as the precipitate

layer forms the dissolution reaction becomes diffusion limited and the slope approaches

1/2. As saturation is approached (i.e. C/C, -- 1), the slope approaches 0. Curve B




























I STAGE 3 I
Layer Diffusion Controlled


0 1
Reaction (Log,X)


Slope of logL vs. logt as a function of reaction extent based on Savannah
River leachability model. Curve A shows behavior in a system where
leaching is diffusion-controlled; Curve B shows saturation-controlled
leaching. Adapted from Wicks [Wic92]. Reprinted by permission of
Noyes Publishing Co.


Figure 2-6.







29

demonstrates the effect of leaching at high SA/ where solution saturation effects stop

the corrosion process before a precipitate layer may form.


The Thermodynamic Model


The thermodynamic model of glass corrosion was developed by Plodinec and

Jantzen of Savannah River Laboratory [Plo84, Jan92] and is based upon the earlier work

of Newton and Paul [Pau77, Pau82]. This model treats the glass as a mechanical mixture

of silicate and oxide components and assumes the overall free energy of hydration is

simply the sum of the free energy of hydration of the individual components. Calculation

of a composite Gibbs free energy of hydration is made by distributing modifying elements

into available silicates and treating glass-formers and leftover SiO2 individually.

Mathematically,


A Gh= x(A G hd) (2-20)


where AGhyd is the Gibbs free energy of hydration of the glass, xi is the mole fraction of

component i, (AGhyd)i is the Gibbs free energy of hydration of component i.

Since many glass corrosion reactions involve pH excursions, allowance has been

made for the dissociation of silicic and boric acid at high pH [Jan92]. For H2SiO'

A(AG,=1.3f 1 ++ l 10+ _- (2-21)
10-p" 10-*pH 1)









and for H2BO3

10( -9.18 10-21.89 10-35.69 \\
A(AG,)=1.364 -log 1+ + +-. 10- 10 (2-22)
10-pH 10-2p 10-3pH J


Based on studies of over 300 glass compositions, Jantzen determined that a linear

relationship existed between the pH-corrected free energy of hydration of the glass and

the log of the normalized silicon mass loss from a 28 day MCC-1 [MCC83] leach test.

This is shown in Figure 2-7.

Jantzen's work is of particular importance in predicting the long-term performance

(-105 years) of nuclear waste glasses via thermodynamic correlation with naturally-

occurring glasses which are known to be stable in the environment on a geologic

timescale [Jan86, Ewi87].


Geochemical Modelling of Glass Corrosion


Computer modelling has been used to predict corrosion of mineral systems [Gra84,

Gra92] and was first applied to nuclear waste glasses by Bernd Grambow. This approach

treats congruent dissolution of the glass as a source term for entry of glass components

into solution. Once components enter solution, the model considers saturation and

precipitation and predicts the thermodynamically favored precipitation products and

corresponding solution concentrations. Because the model is thermodynamic in nature,

the occurrence of these processes is expressed as a function of reaction extent, rather than

time.



















Legend
a ACTUAL
10000 x BASALT
o BOROSIL
2 LogSi--0.1636G(hyd) + 0.3557 = 0.73 a CHINESE
2 I EGYPTIAN
S1000- FRENCH
-* FRITS
ix B0 GLCERAM
0 0 GRANITE
S 100 2 4 HIGHSI
L/) I/ 1 ISLAMIC
LUNAR
7 MEDIEVAL
o 10' a MISC
N a MIXALK
SO OBSIDIAN
1 x ROMAN
+ /'+ w 0 SRL
0 a TEKTITE
Z f VENETIAN
C5 + WASTE
0.1
10 5 0 -5 -10 -15 -20
FREE ENERGY OF HYDRATION ( kcal / mole )











Figure 2-7. Linear regression plot of over 300 leach tests relating AGhyd calculated
from glass composition and pH to log silicon release for 28 day static
leach tests. Adapted from Jantzen [Jan92]. Reprinted by permission of
Noyes Publishing Co.







32

In Grambow's early work, he noted that for glasses leached in buffered solutions

at various pH values, the concentration of Ca" behaved as though it were in equilibrium

with solid CaCO3 [Gra82]. Grambow later adapted a geochemical computer code

(PHREEQE) to model the formation of glass alteration products. The output of this

model is shown in Figure 2-8 and shows a close correspondence to measured values.

PHREEQE is also capable of accounting for the presence of reaction products from

corrosion of other parts of a waste package, such as the stainless steel canister.

The geochemical model considers the rate-limiting step in corrosion to be the

irreversible decomposition of an activated surface complex. The overall reaction rate of

the glass is given by the product of the concentration of the activated complex and a

decomposition frequency factor. The affinity of the reaction is given by the ratio of the

ion activity product in solution to the equilibrium constant for the reaction. According

to Grambow, the cessation of leaching in high silica solutions is due to saturation of the

solution with respect to the activated surface complex, rather than with respect to the

glass.





















8 pH


REACTION PROGRESS. g/m3


Reaction of nuclear waste glass with 0.001 MgCl2 solution. Solid lines are
the result of modelling using PHREEQE. Data points are experimental
results. Adapted from Grambow and Strachan [Gra84]. Reprinted by
permission of the Materials Research Society and Bernd Grambow.


10'






101



z
0
i
S10'
I.--
z
U
u

U
2



10
oc
0






1





10-'


Figure 2-8.













CHAPTER 3
OBJECTIVES AND ACCOMPLISHMENTS


The principal aim of this study was to evaluate mechanisms of glass corrosion

using a variety of surface and solution analytical techniques. This strategy was applied

first to simple binary alkali-silicate glasses leached in deionized water and is discussed

in Chapter 4. Information gained from study of this system was then applied to simulated

nuclear waste glass alteration in deionized water and "repository-relevant" leachants. This

is discussed in Chapter 5.

Specifically, the objectives of this work were to

1) develop and apply an integrated characterization methodology to study

composition, structure and microstructure in leached glasses

2) examine in detail the microstructure of glass alteration products

3) develop a model relating alteration product microstructure to glass leaching

mechanisms and kinetics.

As a result of this effort, three characteristic leaching phenomena were identified

in alkali-silicate glasses, based on analysis of microstructure and leaching kinetics. These

were

1) alkali removal with silica network preservation

2) congruent dissolution with precipitation of colloidal silica

3) congruent dissolution.








35

Based on these results, a model was proposed which explains the evolution of

these structures and the associated leaching kinetics. The model is based on

considerations of solution chemistry within the hydrodynamic boundary layer (HDBL)

adjacent to the glass surface and its effect on alteration product microstructure. The

validity of the model was confirmed by direct measurement of HDBL chemistry using a

novel sampling approach in order to obtain solution samples adjacent to the glass surface.

The methodology developed in this effort was further utilized to study the

alteration of simulated nuclear waste glass in deionized water, granitic groundwater and

synthetic brine. Studies of alteration product microstructure identified dissolution and

precipitation as the most likely mode of alteration. Diffusion-limited leaching kinetics

were identified in some cases and were explained based on saturation effects within the

pores of the alteration layer.













CHAPTER 4
STRUCTURAL, MICROSTRUCTURAL AND KINETIC ASPECTS
OF CORROSION IN BINARY ALKALI-SILICATE GLASSES



The objective of the work described in this chapter was to utilize surface analytical

tools to assess changes due to corrosion in R20-2SiO2 (R = Li, Na, K) glasses. In

particular, microstructural alteration and its effect on leaching kinetics were examined.

Glass specimens were leached in flowing deionized water and analyzed by visual

inspection, scanning electron microscopy (SEM), transmission electron microscopy

(TEM), BET gas adsorption analysis and small-angle neutron scattering (SANS) to assess

microstructural features over five orders of magnitude, from approximately 10 A to 100

pm. Leaching-induced changes in nearest-neighbor atomic structure were assessed using

Fourier transform infrared reflection spectroscopy (FTIRRS) and x-ray photoelectron

spectroscopy (XPS). Leaching kinetics were examined by measuring the rate of

appearance of glass constituent elements in solution using inductively coupled plasma

(ICP) spectroscopy.


Experimental


Alkali-silicate glasses were made by combining appropriate amounts of reagent-

grade alkali carbonates and silica and mixing them for a minimum of 24 hours in a jar

mill. Mixtures were melted in a platimum crucible in an electric furnace between 1200

36








37
and 15000C for a minimum of 24 hours and cast into 1 cm x 1 cm x 5 cm bars.

Solidified bars were annealed at 5000C for one hour and allowed to furnace cool to room

temperature. Bars were stored in a desiccator until needed.

Individual glass specimens were cut from the cast bars using a low-speed diamond

saw. Bars of Li2O-2SiO2 and Na20-2SiO2 glasses were cut into 1 cm x 1 cm x 0.2 cm

specimens; K20.2SiO2 specimens were 1 cm x 1 cm x 1 cm. Samples were polished on

all sides using 400 and 600 grit silicon carbide paper, followed by 1 pm diamond paste.

Polished samples were wiped with a soft cloth and washed ultrasonically for 15 minutes

in ethanol, as specified by MCC protocol [Mat83]. Alcohol used in cleaning was replaced

with fresh ethanol at five minute intervals. Prepared specimens were stored in a

desiccator until used in corrosion studies.

Glasses were leached in teflon containers in flowing deionized water at 700C,

similar to the MCC-4 test [Mat83]. Photographs of the corrosion system are shown in

Figure 4-1. Leachant flow rates and glass surface area-to-solution volume ratios (SA/V)

were controlled in order to maintain the pH as close to neutral as possible for each glass.

This is a particularly important aspect of the study, since accumulation of corrosion

products and pH excursions may impact both the mechanisms and kinetics of corrosion

[San73, Eth77, Wan58]. The duration of each study was adjusted to provide sufficient

leached layer for study and varied from six minutes in the case of the least durable glass

(KO2-2Si2O) to 35 days for the most durable glass (Li2O-2SiO2). Leachant flow rate,

residence time, SA/V, pH and test duration are shown in Table 4-1 for each glass studied.























































Photograph of (a) corrosion system overview showing dionized water
reservoir, peristaltic pump, constant-temperature cabinet, leaching vessel
and collection bottle and (b) corrosion cell.


Figure 4-1.














o -h
Yi
m. ~C *








0a












<8
(j .


or e


q 00~













00 '2
-^ m








40

Leachate samples were collected at appropriate intervals, acidified with nitric acid

[MCC83] and analyzed using ICP. At the conclusion of the leaching study, glass samples

were removed from the leaching vessel, rinsed in deionized water and transferred into

increasingly alcoholic mixtures of water and ethanol. Samples were hypercritically dried

under CO2 [Lau86, Fil86] using ethanol as a transfer liquid. Hypercritical drying is a

particularly important (and largely neglected) aspect of corrosion sample treatment.

Drying in this manner avoids the formation of a meniscus in the pores of the leached

layer. Drying stresses are thus avoided and fine-scale microstructural features are

preserved [Sch90]. It was also found that samples dried in this way had better structural

integrity than those dried in air. Leached specimens were stored in a desiccator pending

analysis.

In addition to MCC-4-type testing, tests were conducted in a novel leaching cell

devised to permit separate, simultaneous solution specimens to be obtained from bulk

solution and the solution directly adjacent to the glass surface. This was accomplished

by adding a third port to the leaching flow cell described previously, as shown in Figure

4-2. Water was pumped into the cell through one port and allowed to flow out via the

second. Small-bore tubing was passed through the third port into the container and its

end firmly held against the glass surface. Water was very slowly pumped out of this port

in order to sample the solution at the plane where it contacted the glass.






















Surface
Sampler

Outlet
(b)





-Glass


Corrosion cell modified to allow sampling at the surface of glass: (a)
photograph; (b) schematic.


Inlet


Figure 4-2.










Results


Visual Inspection


The macroscopic appearance of the glasses before and after leaching is shown in

Figure 4-3. Prior to leaching all glasses were transparent and clear. After leaching for

35 days, the Li2O-2SiO2 glass was clear and shiny, but contained numerous surface

cracks. These cracks began forming shortly after the glass had been removed from the

leaching solution and continued to form over a period of several days. The Na20O2SiO2

glass was opaque and extremely delicate after 10 hours leaching. Mechanical integrity

was so low that several samples were destroyed during handling. Finally, the overall

appearance of K20-2SiO2 glass was unchanged by leaching; however, the dimensions of

the sample were drastically reduced by leaching for approximately six minutes.


Scanning Electron Microscopy


Microstructure on the order of several millimeters down to approximately 0.05 p.m

was examined using SEM. Specimens were examined both in cross-section (obtained by

fracturing the sample) and face-on.

Figure 4-4 shows an SEM of a cross-section of Li20.2SiO2. The leached layer can

be easily discerned from the underlying glass. Large cracks and surface "channels" where

preferential dissolution has occurred are also visible. Higher magnification of this region

showed numerous small cracks throughout the layer. These cracks were not present in

the unleached glass.












Li20-2SiO2
Unleached

Leached I


Na20-2SiO2


LI


K20-2SiO,

L i


Figure 4-3. Macroscopic appearance of binary glasses in leached and unleached states.





























Figure 4-4. Scanning electron micrographs of fracture surface of leached
Li20.2SiO2: (a) 35x; (b) 1,000x; (c) 35,000x.







45





(a)





















(b)













































































*. .


LA







47

The surface of leached Li2O-2SiO2 glass is shown in Figure 4-5. Cracks are

visible on the surface along with small pits and channels where preferential corrosion

appears to have taken place. It is significant that polishing scratches are still visible on

the surface, since this indicates that appreciable dissolution of the silica network has not

occurred.

Micrographs of a cross-sectional fracture surface of Na2O-2SiO2 are shown in

Figure 4-6. At low magnification it is clear that the leached layer has a very disrupted

microstructure, with numerous cracks and extensive pitting compared to the underlying

glass. High magnification in Figure 4-6c shows that, on a small scale, the altered glass

is not homogeneous but is composed of densely packed particles with diameters on the

order of 0.07 L.m.

The surface of leached Na2O-2SiO2 is shown in Figure 4-7. The appearance of

this glass is drastically different from the Li20-2SiO2 glass. Macroscopically, it is roughly

textured and opaque. Microscopically it has a structure which is dominated by large,

hemispherical pits. At high magnifications (Figure 4-7c) the pit edges show a terraced

structure. The mechanism of formation of these terraced pits is uncertain.

SEM examination of the leached K20-2SiO2 glass, shown in Figures 4-8 and 4-9,

revealed an extremely thin (<0.1 pm) reacted layer with no discerable microstructural

features. Some regions of layer formation on the order of 1 gtm were found in places, as

noted in Figure 4-8b. This layer, when present, was cracked and partially separated from

the underlying glass.





























Figure 4-5. Scanning electron micrographs of leached Li20O2SiO2 surface:
(a) 35x; (b) 1,000x; (c) 35,000x.







49





(a)






















(b)







50












(c)





























Figure 4-6. Scanning electron micrographs of fracture surface of leached
Na2O.2SiO2: (a) 35x; (b) 200x; (c) 35,000x.







52





(a)








I














(b)







53












(c)






























Figure 4-7. Scanning electron micrographs of leached Na2O-2SiO2 surface: (a)
35x; (b) 200x; (c) 600x.







55





(a)























(b)







56












(c)






























Figure 4-8.


Scanning electron micrographs of fracture surface of leached
K20.2SiO2: (a) 35x; (b) 30,000x.












(a)


















, 9111 (b)



1






























Figure 4-9. Scanning electron micrographs of leached K20-2SiO2 surface: (a)
200x; (b) 750x.







60





(a)





















(b)










Transmission Electron Microscopy


Small-scale microstructure, on the order of 5-500 nm was examined using

transmission electron microscopy (TEM). Specimens were prepared using a technique

described by Bunker et al. [Bun84] and Randall [Ran87] in which leached layers were

scraped from the glass using a diamond-tipped stylus into a container of 1,1,1

trichoroethane. Suspended particles were dispersed by high intensity sonication for 15 -

20 minutes. The resulting slurry was placed dropwise onto a warm formvar-coated

copper TEM grid, and the trichloroethane was allowed to evaporate.

Examination of Li20-2SiO2 revealed numerous particles such as the one shown in

Figure 4-10. These particles had smooth surfaces and a reasonably homogeneous

microstructure on the scales studied here. Selected area electron diffraction (SAED),

shown in Figure 4-10b, showed diffraction rings, indicating some degree of crystallinity

in this material; however, x-ray diffraction analysis of the leached glass did not indicate

crystallinity, suggesting that the ordering found by SAED occurs on a small scale,

possibly as isolated crystallites.

In contrast, the leached Na2O-2SiO2 glass is roughly textured and appears to

consist of connected particles approximately 7-16 nm in diameter with void spaces in

between, as shown in Figure 4-11. SAED showed this material to be completely

amorphous. Leached K20-2SiO2 was not examined, since it lacked sufficient layer for

study.































Figure 4-10.


Transmission electron microscopic anllN 'is of fragment of leached
Li2O-2SiO2: (a) bright-field image; (b) selected area electron
diffraction pattern.








63






(a)







A".4







100 nm I










(b)





























Figure 4-11. Transmission electron microscopic analysis of leached Na2O-2SiO2
fragment: (a) bright-field image; (b) selected area electron
diffraction pattern.







65






(a)

























(b)









Small Angle Neutron Scattering


Small angle neutron scattering (SANS) measurements were used to determine

microstructure correlation lengths and to investigate any fractal properties in the leached

material. All measurements were made on the 30-meter neutron scattering camera at the

National Center for Small Angle Scattering Research at Oak Ridge National Laboratory.

SANS is sensitive to structural inhomogeneities and is useful in the study of small-

scale microstructure. Scattering occurs as a result of neutron interaction with spatial

variations in the distribution of matter. In the case of leached glass, this variation is due

to the presence of silica and pore space [Tom83, Sch87, Sch89].

The central problem of SANS work involves determination of the structure

responsible for a given scattering pattern. Several models are available to address this

issue. The Debye-Bueche model [Deb49, Deb57, Lon74, Wig90] was chosen for this

work because it is applicable to a random, interpenetrating two-phase system and is

capable of determining correlation lengths in porous material. According to the Debye-

Bueche model, scattering curves may be described as

A 41W
I(Q)= 1 +A2e 4 (4-1)
(1+Q2a?)2


where Q is the scattering vector, I(Q) is the scattering intensity at a given value of Q, A,

and A2 are fitting parameters and a, and a2 are correlation lengths.

SANS has also been used extensively to probe fractal aspects of materials [Bal84,

Cra86, Hen90, Sch86, Sch89a, Sch89c]. A fractal object is one which displays "dilation

symmetry" or "scale invariance." This means simply that the object appears similar at








67

varying length scales. Coastlines, trees and river deltas are familiar examples.

Mathematically, such structures are characterized by a fractional dimensionality. Surface

fractals obey the relation



S-RD, (4-2)


where S is surface area, R is the object size and D, is the surface dimension (D, = 2 for

a smooth surface). Alternatively, an object is said to be mass fractal if it obeys the

relation
M-R (4-3)


where M is the mass of the object, R is the object size and D is the fractal dimension.

Measurement of the fractal aspects of an object by small angle scattering

techniques is made possible by a power law dependence of scattering intensity vs.

scattering vector
I(Q)Q-ZfD, (4-4)


where all variables have the same meaning as previously discussed. At large values of

Q, scattering is due to interaction with primary particle surfaces. This region of the curve

is known as the Porod regime and displays a -4 power law dependence for a smooth

surface. A fractally rough surface will result in a deviation from this behavior and will

display a power law exponent between -3 and -4.

At smaller Q values, collections of primary particles give rise to scattering. This

region of the curve contains information from larger microstructures and is known as








68

the Guinier regime. On this scale of measurement, the surfaces of the primary particles

appear smooth and power law exponents between -1 and -3 would be expected.

The scattering curve of leached Li20-2SiO2 is shown in Figure 4-12. This sample

was a weak scatterer and required a 12-hour collection time to accumulate sufficient data.

The scattering curve is presented in two segments, since two camera lengths were used

to cover a larger range of Q. The region of the curve corresponding to the smallest scale

(Q values ranging from 1.25 to 0.25 nm ') shows no structure. At scattering vectors less

than 0.25 nm ', results demonstrate power law scattering with an exponent of -4.24.

There is sufficient spread in the results that an exponent of -4.0 cannot be ruled out

within a reasonable confidence interval. This appears to be Porod scattering behavior,

indicative of smooth surfaces; however, the lengths being probed in this region correspond

to length scales of several hundred nanometers, which is considerably larger than a

primary particle. This data may be the result of scattering from the fracture surfaces

observed by SEM.

Figure 4-13 presents the scattering curve of leached Na20.2SiO2. This curve

clearly demonstrates Porod scattering behavior from smooth particle surfaces at high

scattering vector values. At these values, length scales of a few nanometers are being

probed, corresponding to surfaces of the primary particles which were observed by TEM.

At intermediate Q values, the scattering exponent is approximately -1, and at the largest

Q values, a slope of -4.12 is observed. At large Q values, scattering is due to neutron

interactions with the surfaces of the 700 nm particles which were identified by SEM. No

clear surface fractal aspects were observed in any of the curves. However,










































-1.6 -1.4 -1.2 -1.0 -0.8 -0.6


-0.4 -0.2 0


Log Q (nm"1)


Figure 4-12.


Small angle neutron scattering curve of leached Li20-2SiO2. The two data
segments are from different camera lengths. Low-Q portions of the
curves have slopes of approximately -4.24.


1.0



0.0


-2.0 -



-3.0


-4.0


Li20-2SiO2


CPO t %






Oo o


0 0
3a


I I I I I I I I I I I I


11111.......






































-1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0


Log Q (nm1)


Figure 4-13.


Small angle neutron scattering curve of leached Na20.2SiO2. Slope in the
high Q region is approximately -4.0 and is -4.12 in the low Q region.


1.0 -


-1.0


-2.0


-3.0-


-4.0


Na2O-2SiO,


Cbo

\Q


a a a a I







71

because of statistical variations present in linear curve fitting, small deviations from

integer dimensionality cannot be ruled out.

Further analysis of the Na2O-2SiO2 curve by Debye-Bueche methods detected

correlation lengths of 29 A and 642 A, which correspond approximately to the structure

scales observed by TEM and SEM, respectively.


BET Gas Adsorption Analysis


Results from BET nitrogen adsorption analysis of leached Na2O-2SiO2 indicate that

the surface area of a single sample increased from 7.26 cm2 for an unleached specimen

to approximately 80,000 cm2 after leaching, an increase of over four orders of magnitude.

These results are consistent with those of Walker [Wal77] for Bioglass leached in 0.1M

TRIS buffer at 370C. Pore size analysis is shown in Figures 4-14 and 4-15. Results

presented here have been normalized to the original geometric surface area of the glass

instead of the more traditional sample mass. This was done because both leached

surfaces and unleached interiors were present in these samples. Thus, these measurements

indicate the amount of pore volume present per unit of original geometrical surface area.

These results show a narrow pore size distribution centered around a diameter of 35 A,

with a second, wider distribution ranging from 60 to 300 A. Bunker et al. [Bun88] found

a similar distribution of pores under 30 A diameter in studies of leached alkali

borosilicate glasses. Corrosion of Li2O-2SiO2 and K20-2SiO2 did not produce sufficient

surface area to allow study by gas adsorption methods.



















0.00408
0.00408 Na2 02S102
0.00374 Cumulative Desorption
Pore Volume
0.00340 -
E
o 0.00306-
E 0.00272-
aU 0.00238 -
3 0.00204-
-J
0 0.00170-
W 0.00136-
0
L 0.00102-
0.00068 -
0.00034 -
0.000
10 100 1000
PORE DIAMETER, (A)













Figure 4-14. Cumulative desorption pore volume of leached Na20-2SiO2 measured by
BET.






















0E
cn
E

V
x
w
L-J

0
w
0


37.4

3.4

30.6

27.2

23.8

20.4-

17.0 -

13.6 -

10.2

6.8-

3.4
0-
10


100 1000
PORE DIAMETER, (A)


Figure 4-15. Pore size distribution of leached Na20-2SiO2 as measured by BET.









Fourier Transform Infrared Reflection Spectroscopy


Glass surface structure and composition were probed using specular reflectance

Fourier transform infrared spectroscopy (FTIRRS) [And50, Swe69, Ger87]. Binary

glasses exhibit two broad reflectance peaks in the range of 800 to 1200 cm-'. The peak

centered at 1050 cm-1 is due to linear vibrations of siloxane bonds. Non-bridging oxygen

(NBO) bonds give rise to the other peak at 975 cm-' [San74, Cla77, Cla79, Che81,

Hus90]. Since modifier content correlates with the number of NBO sites in the glass, the

relative intensity of these two peaks is indicative of both structure and composition. In

addition, since a rough surface tends to scatter rather than reflect incident radiation,

decreases in the overall intensity of the spectrum indicate an increase in the degree of

surface roughening.

Spectra of leached and unleached binary glasses are shown in Figures 4-16 through

4-18. The spectrum of vitreous silica is also shown in each figure. In the case of

Li20.2SiO2 glass, upon leaching, the NBO peak disappears, the bridging oxygen peak

intensifies, and the overall shape of the spectrum very closely approaches that of vitreous

silica.

Leached Na2O-2SiO2 shows very similar behavior; however the intensity of its

spectrum is much less than that of vitreous silica, indicating a rough surface. These

results demonstrate that the composition of the leached surfaces of LizO.2SiOz and

Na2O-2SiO2 are both similar in composition and structure to vitreous silica, due to the

formation of bridging oxygen bonds at the expense of NBO bonds during leaching.













40
Li20.2SiO2
Vitreous Silica S
33.5 -


S26.8-
z/
O 20.1 I \, Unleached
SI'
LL.
ac 13.4 -

6.7- Leached/
6.7


1400 1275 1150 1025 900 775 650 525 400
WAVENUMBER











Figure 4-16. FTIRRS spectrum of Li2O-2SiO2 before and after leaching. The spectrum
of vitreous silica is shown for reference.


















40-


33.5 -


uJ 26.8-
0
z

0 20.1-
-j
LL
: 13.4 -


6.7-


0-
1400


Figure 4-17.


1275 1150 1025 900 775 650 525 400
WAVENUMBER












FTIRRS spectrum of Na20-2SiO2 before and after leaching. The spectrum
of vitreous silica is shown for reference.



















33.5


U 26.8
0
Z
4
F-
S20.1
-J
LI.
- 13.4


1400 1275 1150 1025 900 775 650 525 400
WAVENUMBER













Figure 4-18. FTIRR spectrum of K20-2SiO2 before and after leaching. The spectrum
of vitreous silica is included for reference.








78

The two glass surfaces differ, however, in that NaO2-2Si02 is rougher and scatters more

strongly than Li20-2Si02.

FTIRRS measurements of K20-SiO2 show that leaching has little effect on the

shape of the spectrum, demonstrating that the leached surface has a composition and

structure nearly identical to the unleached surface. However, the leached glass spectrum

has a lower intensity than the unleached glass, due to surface roughening.


X-ray Photoelectron Spectroscopy


Near-surface atomic structure was studied using XPS. XPS is sensitive to the

bonding state of a given element. Thus, it was possible to measure the binding energy

of Ols electrons in order to determine the relative proportions of oxygen atoms involved

in bridging and non-bridging bonds [Vea80,Spr90]. Also, because XPS peak area is

proportional to concentration, it was possible to determine surface concentrations of each

glass element based on Ols, Si2p, Lils, Nakll and K2p peaks.

Since this technique measures only the outer few atomic layers, and because

simple exposure to atmosphere is sufficient to induce changes in this region of the glass,

unleached glasses were fractured in the vacuum chamber of the XPS system to provide

a fresh, unreacted surface for analysis. Leached samples were examined in "as received"

condition.

The binding energy distribution of the Ols electron is shown in Figure 4-19 for

unleached and leached Li20-2SiO2 glass. Peaks from bridging and non-bridging oxygen

bonds are not completely resolved in these spectra and appear as an asymetry in the











































BINDING ENERGY


Figure 4-19. XPS of Ols line of Li2-02SiO2 glass: (a) unleached; (b) leached.







80

overall band. The individual contributions of each type of bond have been resolved by

fitting Gaussian distributions to the composite curve. In XPS, peak area scales with

concentration so the relative amounts of each type of bond may be determined. A

contribution from NBO bonds clearly can be seen in the spectrum of the unleached glass.

After leaching this contribution is lower, and the spectrum is dominated by the lower

binding energy peak. Virtually identical results were obtained for the Na20.2SiO2 glass,

as shown in Figure 4-20.

In the case of K20-2SiO2, shown in Figure 4-21, the Ols spectrum of the leached

sample is very similar to that of the unleached sample. The NBO peak has lost only a

small portion of its area as a result of leaching. This suggests that surface alteration

leaves a leached surface very nearly identical in structure and composition to that of the

unleached surface. Surface compositions of leached and unleached samples were also

determined [Esc75] and are summarized in Table 4-2.


Leachate Analysis


The rate at which glass component elements appear in solution provides insight

into the mechanism and rate of reactions occurring at the glass surface. The leach rates

of silicon and lithium from Li2O-2SiO2 are shown in Figure 4-22. Small amounts of

silicon appeared in solution during the first few sampling intervals but rapidly fell below

the detection limits of ICP. The leach rate of lithium decayed rapidly over the first few

days of the study. Since these glasses contain equimolar amounts of modifier and silicon,

preferential or congruent dissolution may be assessed by comparing the leach rates of













(a)
XPS 01s
Na20 2S102
Unleached

wZ










540 538 536 534 532
BINDING ENERGY



Leached
IU




Li














(b)
540 538 536 534 532 53
BINDING ENERGY






Figure 4-20. XPS of Ols line of Na SiO glass: (a) leached; (b) unleashed.
PI- (b)


I-






538 536 534 532 530
BINDING ENERGY









Figure 4-20. XPS of Ols line of Na2O02SiO2 glass: (a) leached; (b) unleached.



























BINDING ENERGY


BINDING ENERGY


Figure 4-21. XPS of Ols line of KO2-2SiO2 glass: (a) unleached; (b) leached.















Table 4-2. Surface Composition Determined by
X-Ray Photoelectron Spectroscopy


Sample O Si R
atomic% atomic% atomic%


Li20-2SiO2 57 23 20
Unleached

Li20-2SiO2 69 28 3
Leached

Na20-2SiO2 53 26 21
Unleached

Na20-2SiO2 65 27 8
Leached

K2O-2SiO2 56 20 24
Unleached

K2O*2SiO2 64 17 19
Leached

SiO2 68 32 --















0.5--


0.4 L20 2Si02
Cd Leach Rate
E Li

E 0.3 Predicted result
%w from Q = at.535
I-
C 0.2 -

SI
0.1



0 10000 20000 30000 40000 50000
CORROSION TIME (min)











Figure 4-22. Leach rates of Li and Si from Li20-2SiO2 during a 35-day corrosion test.
Data points are measured leach rates. Solid line is fit to Q = at0535







85

the two elements. If the glass were dissolving congruently, the leach rates of the two

elements should coincide. A difference in leach rates between the two components

indicates selective leaching. Based on this explanation, it is clear that lithium is

selectively removed from this glass.

The overall shape of the lithium leach rate curve suggests a diffusion-limited

process, like that proposed by Rana and Douglas [Ran61a,b]. To test this possibility, data

were fit to equation 2-13 by plotting logQ vs. logt and determining the slope, which is

predicted to be 0.5 for a diffusion-limited process. This plot is shown in Figure 4-23.

Data taken at later times are linear and have a slope of 0.535, an intercept value of

0.00525 mol/m2, and a correlation coefficient of 0.999, indicating a high quality fit. It

was noted that data obtained at short times are not linear and have a slope greater than

0.5. This deviation from t.05 behavior may be explained by mixing effects within the

leaching cell and the fact that the time required for sampling is long compared to the rate

of change of the glass leach rate at early times in the experiment. Within the first few

hours of the test, the glass leach rate is changing rapidly during the 30-minute sampling

interval. Thus, solution analysis is measuring a weighted average of glass leach rate over

the course of the sampling time, resulting in skewed data. To test this hypothesis, a

simple BASIC computer program was written to calculate the solution values which

would be measured throughout the experiment, based on mixing and sampling effects and

assuming a leach rate based on parameters measured at long times where logQ vs. logt

was linear. The predicted results are plotted in Figure 4-22 along with the data and show

a very close match. For this reason, it is concluded that the glass leached with a t0.535

time dependence throughout the study.




















Li2 0 2SiO
Cumulative Leached Li j


-0.2


-0.6


-1


-1.4


-1.8


-2.2

















Figure 4-23.


""""
Dr


'"Slope = 0.535














! I I I I I I I I


1.4 1.8 2.2 2.6 3 3.4 3.8 4.2 4.6
log t (min)


Logarithmic plot of cumulative amount of lithium leached from glass vs.
time. The slope of approximately 0.5 indicates a diffusion-limited process.








87

Leaching results for Na2O-2SiO2 are presented in Figure 4-24. This graph shows

that after an initial mixing transient, sodium is removed from the glass at a nearly

constant rate. Silicon, however, is very slow to appear in solution, but after

approximately 30 minutes, its leach rate rises rapidly to approximately 9.5 mol-m2-d-1 and

then gradually increases further until it matches the sodium leach rate. Thus, leaching is

initially by selective removal of sodium and ultimately evolves to congruent dissolution.

These results do not correlate with any established kinetic model.

Leaching of K20-2SiO2 is shown in Figure 4-25. In this glass, silicon and

potassium appear in solution at the same rate, indicating congruent dissolution. This

figure also shows that leach rate is nearly constant over the duration of the experiment.


Surface/Bulk Solution Studies


In a few instances has it been recognized that solution conditions immediately

adjacent to the surface of a corroding glass may differ from conditions in the bulk

solution [Cla83, Sa184, Gra86, Bun88, Wic92, Gra92]. This issue is particularly

important, since it is the solution within the hydrodynamic boundary layer (HDBL) which

reacts with the glass. To date, no direct measurements have been made on this

hypothetical entity. Obtaining such measurements was the objective of this particular

portion of the work.

Samples were obtained at early leaching times from both the bulk solution and

also from solution next to the glass surface as described previously. Solutions were

analyzed for pH and glass constituents. The results of these analyses are summarized








88









16
O
f14 O *

E 12 o
S10 o
E 0
o o Na20 2S102

So o o Leach Rate
o Na
S6 oSI


o
2 -
o
0
0 IdI I I I I I-
0 200 400 600
CORROSION TIME (min)


Figure 4-24. Time dependence of the leach rates of Na and Si from Na202SiO2 glass.
















5000


"4000 00
4000 0600o o

E -
0 3000
E K20 2S1O2
S Leach Rate
0 2000 oSI


* 1000-


0 -I I I I II
0 2 4 6
CORROSION TIME (min)


Time dependence of the leach rate of K and Si from K20O2SiO2.


Figure 4-25.








90

in Table 4-3. In this table, surface values are expressed as the minimum value for that

parameter, since the measured values are a function of sampler flow rate. Ideally, such

a sample should be collected infinitely slowly to avoid dilution by the bulk solution.

Since this is not practical, it is likely that the true values were reduced somewhat by

dilution from non-ideal sampling; therefore, the figures presented here represent a lower

limit to the actual value.

As shown in Table 4-3, the difference between conditions in the bulk and surface

solutions is greatest in the K20-2SiO2 glass, which corrodes most rapidly, followed by

Na2O-2SiO2. Measurements of Li20-2SiO2 show the smallest difference between surface

and bulk values.


Summary, Model and Discussion


Corrosion of Li,02SiO2


This glass proved to be the most durable of the three compositions studied.

Polishing scratches, still visible on the glass surface after corrosion, demonstrate that the

silica network was not significantly disrupted during corrosion. XPS spectra show that

lithium is depleted at the glass surface, and infrared reflection spectra indicate that the

corroded surface is similar in structure to vitreous silica. The numerous cracks which

formed during drying suggest that silanol condensation occurred, since this is known to

result in tension and subsequent cracking in the leached surface [Bun83, Bun88].

Microscopic studies using SEM and TEM showed that the alteration layer had a

homogeneous structure but with numerous cracks. This sample was a weak neutron









91



0
a 0









So 9 o




















d d
o 0 0 0














-o \
vl0
17)b ;t
d U- b^ (
3s "
oX< ^ ^














*nN N3
rt 6 0 ^ e

Ll^^o^ o (
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KINETIC AND MICROSTRUCTURAL ASPECTS OF
THE AQUEOUS ALTERATION OF GLASS
BY
BRUCE K. ZOITOS
A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN
PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
1992
'UNIVERSITY OF FLORIDA LIBRARIES

Copyright 1992
by
Bruce K. Zoitos

For Mom and Dad, of course.
But mostly, for me.

ACKNOWLEDGEMENTS
I wish to thank my advisor, Professor David Clark, for introducing me to the field
of glass corrosion and for the many growth opportunities he made available to me during
my graduate school career. I also thank Professors Stan Bates, Emmett Bolch, Robert
DeHoff, Alex Lodding and E. Dow Whitney for their guidance and participation as
committee members.
1 am very grateful to those individuals whose time and expertise contributed
materially to this work. Guy Latorre provided numerous hours of assistance with both
ICP and FTIRRS studies. I thank Professor Lodding and his staff at Chalmers University
of Technology for countless SIMS profiles and for helping to meet those ever-present
publication deadlines. Professor J.F. Quinson of Universite Claude Bernard was very
generous to provide porosimetric analysis using his "one-of-a-kind" calorimeter. Dr.
David Hensley of the Ceramic Engineering Department at Rutgers University performed
the XPS measurements discussed in this work. A very special thanks goes to Dr. Steve
Spooner of the National Center for Small Angle Scattering Research at Oak Ridge
National Laboratory for giving up several evenings to insure that my samples were
completed within the allotted 48 hours beam time. Thanks go also to Richard Crockett,
Augusto Morrone and Andy Duncan for expert TEM and SEM work.
tv

None of this would have been possible without the financial support of
Westinghouse Savannah River Company and its predecessor, E.I. du Pont de Nemours
and Company, nor would it have been possible without the enthusiasm and personal
support of Dr. George Wicks of WSRC. I am endebted to George for his friendship and
encouragement. It is with much pleasure that 1 thank Drs. Phil Bennett and Vince Puglisi
of Gates Energy Products for tolerating the periodic absence of a certain GEP scientist
during the busier stages of this work.
Finally, I wish to thank all my friends and fellow students for providing the love
and moral support that helped me to stay afloat during some very difficult and painful
times. You are too numerous to mention, and I trust you will not be offended if your
names are omitted. You know who you are. I would like to extend very special thanks
to Beree Darby, who was a sympathetic listener at a time when I needed someone to
listen and Anne Ricker, whose friendship has been a reassuring constant for the last two
years. Lastly, 1 wish to thank my former supervisor, Bob Stosky, for a particular
conversation in December 1990, in which I was reminded of my true reason for coming
to graduate school. That conversation resulted in the appearance of this dissertation
approximately one year later.
v

TABLE OF CONTENTS
ACKNOWLEDGEMENTS iv
ABSTRACT viii
CHAPTERS
1 INTRODUCTION 1
2 OVERVIEW OF AQUEOUS CORROSION IN SILICATE GLASSES 4
Reactions of Amorphous Silica with Water 5
Solubility of Amorphous Silica at 25°C 5
Effect of Temperature on the Solubility of Amorphous Silica 5
Effect of pH on the Solubility of Amorphous Silica 7
Effect of Particle Size on the Solubility of Amorphous Silica 7
Kinetics of Silica Dissolution and Deposition 9
Structure and Corrosion of Alkali-Silicate Glasses 10
The Structure of Alkali-Silicate Glasses 12
Corrosion of Alkali-Silicate Glasses 14
Corrosion of Commercially Important Ternary Glasses 16
Corrosion of Soda-Lime-Silica Glass 17
Corrosion of Sodium Borosilicate Glass 18
Corrosion of Nuclear Waste Glasses 23
Characteristics of Nuclear Waste Glass Alteration Layers 24
The Savannah River Leachability Model 26
The Thermodynamic Model 29
Geochemical Modelling of Glass Corrosion 30
3 OBJECTIVES AND ACCOMPLISHMENTS 34
4 STRUCTURAL, MICROSTRUCTURAL AND KINETIC ASPECTS
OF CORROSION IN BINARY ALKALI-SILICATE GLASSES 36
Experimental 36
Results 42
Visual Inspection 42
vi

Scanning Electron Microscopy 42
Transmission Electron Microscopy 61
Small Angle Neutron Scattering 66
BET Gas Adsorption Analysis 71
Fourier Transform Infrared Reflection Spectroscopy 74
X-ray Photoelectron Spectroscopy 78
Leachate Analysis 80
Surface/Bulk Solution Studies 87
Summary, Model and Discussion 90
Corrosion of Li20-2Si02 90
Corrosion of Na20-2Si02 92
Corrosion of K20-2Si02 95
A Model for Corrosion in Binary Alkali-Silicate Glasses 95
5 AQUEOUS ALTERATION OF
165/TDS SIMULATED NUCLEAR WASTE GLASS 98
Introduction 98
Experimental 99
Glass Processing and Composition 99
Leachants 99
Leach Tests 101
Field Leaching Studies 104
Results 105
Scanning Electron Microscopy 105
Transmission Electron Microscopy 113
Thermoporometry 113
Fourier Transform Infrared Reflection Spectroscopy 118
Secondary Ion Mass Spectrometry 121
Leaching Kinetics 134
Summary and Discussion 138
Corrosion of 165/TDS in Deionized Water 143
Corrosion of 165/TDS in Granitic Groundwater 144
Corrosion of 165/TDS in WIPP-A Brine 144
Correlation of Laboratory and Field Studies 145
6 CONCLUSIONS AND SUGGESTIONS FOR FUTURE WORK 147
Conclusions 147
Future Work 149
REFERENCES 151
vii
BIOGRAPHICAL SKETCH
162

Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy
KINETIC AND MICROSTRUCTURAL ASPECTS OF
THE AQUEOUS ALTERATION OF GLASS
By
Bruce K. Zoitos
May 1992
Chairman: David E. Clark
Major Department: Materials Science and Engineering
The effect of aqueous alteration was examined in R202Si02 glasses, where R
represents Li, Na or K. Glasses were leached at 70°C in flowing deionized water for
periods ranging from five minutes to 40 days. Leached surfaces were examined visually
and by scanning electron microscopy (SEM), transmission electron microscopy (TEM),
Brunauer-Emmett-Teller nitrogen adsorption analysis (BET), small angle neutron
scattering (SANS), Fourier transform infrared reflection spectroscopy (FTIRRS) and x-ray
photoelectron spectroscopy (XPS). Leaching kinetics were evaluated by inductively
coupled plasma spectroscopy (ICP) analysis of leachate solutions.
Drastically different alteration surfaces and kinetics were observed for each glass.
Depending upon the glass, surface layers were composed of the original silica network,
a porous colloidal silica precipitate or were completely absent. Leaching kinetics ranged
from diffusion-limited to linear.
viii

A model was developed to explain these differences, based on the solution
chemistry of the hydrodynamic boundary layer adjacent to the glass surface and its effect
on glass alteration. Model predictions were validated by direct measurement of solution
parameters within this boundary layer.
A similar methodology was used to evaluate alteration product formation in a
simulated nuclear waste glass leached at 90°C in deionized water and in granitic
groundwater and synthetic brine, which are considered to be "repository-relevant"
leachants. Corrosion in deionized water and granitic groundwater leads to a porous,
precipitate-like alteration product. Kinetic measurements indicate that this product serves
to decrease the alteration rate of the underlying glass. In brine, a thin brine precipitate
layer forms on the glass surface which appears to drastically reduce the corrosion rate of
the glass.
tx

CHAPTER 1
INTRODUCTION
At the time of this writing, nearly 1.3 billion Curies (4.4 x 1019 Becquerel) of
defense high level radioactive waste (HLW), mostly in liquid form, await processing at
four U.S. sites [Wic92], The first U.S. HLW vitrification plant, the Defense Waste
Processing Facility (DWPF), is scheduled to begin operation this year at Savannah River
Site using an optimized glass composition designated 165/TDS. One of the primary
design targets for this glass was that it have a low aqueous corrosion rate.
Glass is the material of choice for most applications which require chemical
durability. It is inexpensive, raw materials are readily available in large quantities, it is
easily manufactured and its composition may be tailored to suit a given application. By
far, the most critical application of a glass product is that of HLW immobilization. Such
use requires a product capable of maintaining its integrity for several hundred thousand
years under "worst case scenario" conditions. The need to understand glass performance
in such an application has motivated most glass corrosion research over the last two
decades.
Prior to interest in nuclear waste glasses, most investigations of durability were
directed at simpler glasses, mostly the alkali-silicates and soda-lime-silica glasses. This
early work was somewhat limited, in that comparatively primitive analytical techniques

2
were available at that time. In addition, much of the work done on simple glass systems
during the 1970s was based on static test methods. In a static test, glass corrodes in a
solution in which dissolved glass components accumulate over time. As a result,
corrosion effects due to intrinsic glass behavior and effects due to the accumulation of
leached glass components in solution cannot be unambiguously determined. As analytical
methods improved during the 1980s and research emphasis shifted to more complex
nuclear waste glasses, few efforts were made to correlate the advancing waste glass
corrosion database with that of simpler, more easily understood glasses. These limitations
in understanding corrosion in simple glass systems have led to a general lack of
consensus on corrosion mechanisms in more complicated glasses.
The primary objective of this dissertation was to address deficiencies in
understanding of glass corrosion through improved studies on binary alkali-silicate
glasses. These studies introduce two innovations to this subject. First, corrosion tests
were designed to limit any effects due to accumulation of leach products in solution. This
was accomplished by leaching glasses in a flowing leachant. Additional test
modifications were made which allowed direct measurement of concentration gradients
between bulk solution and solution adjacent to the glass surface. The existence of such
gradients has long been speculated but has never been verified.
In addition, an effort was made to identify and utilize new analytical methods for
alteration product characterization. This led to a collaboration with workers at the
National Center for Small Angle Scattering Studies at Oak Ridge National Laboratory to
study leached glass microstructure using small-angle neutron scattering techniques, as well

3
as extensive utilization of in-house analytical expertise such as scanning and transmission
electron microscopy. Where possible, these techniques were applied to nuclear waste
glasses in addition to the binary glasses. In some cases, additional techniques were
utilized to circumvent analytical problems inherent to nuclear waste glasses. For example,
complex alteration product compositional profiles were measured quantitatively and to a
high degree of accuracy using secondary ion mass spectrometry techniques developed by
co-workers at Chalmers University of Technology. Thermoporometry, conducted in
collaboration with workers at Universite Claude Bernard in Villeurbanne, France, provided
pore size analysis on very limited amounts of leached nuclear waste glass and did not
require that the sample be dried. The success of these efforts was made possible not only
by utilization of advanced techniques and equipment but also by the expertise and
experience of the individuals who developed and apply them.
Analysis of the information developed over the course of this study demonstrates
that aqueous corrosion can lead to drastically different leaching kinetics and alteration
products depending upon glass composition. These diverse behaviors have been unified
by considering the effect of the inherent glass leach rate on solution chemistry.
Specifically, it suggested that interaction of the glass with the chemistry of the solution
adjacent to the glass surface is the factor which determines the mode in which the glass
reacts.

CHAPTER 2
OVERVIEW OF AQUEOUS CORROSION
IN SILICATE GLASSES
Silicate glasses encompass a family of materials with a wide range of chemical
durability. Within the silicate glasses, composition and leaching conditions exert a strong
influence on durability and corrosion. For instance, specimens of K20-2Si02 placed in
deionized water at 70°C dissolve completely within minutes, while nuclear waste glasses
corrode to only 10-15 pm depth after two years under aggressive laboratory conditions.
While some aspects of glass corrosion are well understood, an all-encompassing
explanation of corrosion in these materials does not currently exist. Instead, several basic
mechanistic phenomena (ion exchange and network dissolution) have been described and
used to explain aspects of the corrosion process, and several models (thermodynamic,
geochemical, surface layer effects) have been proposed to explain and predict corrosion.
Thus, considerable information has been accumulated regarding atomic-level aspects of
alteration as well as global behavior of glass-water systems. Very little information exists
regarding the microstructure of glass ateration products.
The objective of this chapter is to examine previous work conducted on corrosion
in silicate glasses. For purposes of clarity, these glasses will be considered in order of
complexity: amorphous silica, alkali-silicate glasses, commercially important ternary
glasses and multicomponent nuclear waste glasses.
4

5
Reactions of Amorphous Silica with Water
The fundamental reaction between silica and water, as described by Eiler [Eil74],
is
(Si02)x + 2H20 <-> (Si02)x_, + Si(OH)4 (2-1)
The net reaction direction is dictated by conditions such as solubility (supersaturated or
undersaturated), temperature, pH, and silica particle size. The effect of each of these
parameters will be discussed.
Solubility of Amorphous Silica at 25°C
In assessing the solubility of silica at 25°C, Morey et al. [Mor64] noted that
solubility was a strong function of particle size, state of hydration and adsorbed impurities
and that several months were typically required for the silica-water system to reach
equilibrium. After allowing initial concentration transients to subside, a saturation value
of 115 ppm Si02 was noted for dissolved silica in contact with silica gel. A similar value
was obtained by the same authors by extrapolating to 25°C solubility data taken at higher
temperatures by other authors.
Effect of Temperature on the Solubility of Amorphous Silica
The work of Okamoto et al. [Oko57], Lehner and Merril [Lenl7], Elmer and
Nordberg [Elm58], Alexander et al. |Ale54], Krauskopf [Kra56], Kitahara [Kit60], and
White [Whi56] on the solubility of amorphous silica at elevated temperatures was
compiled by Morey et al. [Mor64], The results are shown in Figure 2-1. While these

6
Figure 2-1. The solubility of amorphous silica in water between 0° and 10()°C.
Adapted from Morey [Mor64]. Reprinted by permission of Journal of
Geophysical Research.

7
data show considerable spread, it is clear that silica solubility increases from between 75
and 150 ppm Si02 at 25°C to between 300 and 400 ppm at 90°C.
Effect of pH on the Solubility of Amorphous Silica
Alexander et al. [Ale54] found that the solubility of silica was approximately
constant from pH 1 to 8; however, solubility increased rapidly above pH 8. Using
colorimetric methods, they were able to determine that the increase in dissolved silica
above pH 8 was due to the presence in solution of the H3Si04 ion in addition to Si(OH)4.
They concluded that the reaction
Si(OH)4 + OH <-» (HO)3SiO +H20 (2-2)
dictated silica solubility at high pH, with the stipulation of constant Si(OH)4
concentration. Silica solubility as a function of pH is shown in Figure 2-2.
Effect of Particle Size on the Solubility of Amorphous Silica
Since silica occurs in a number of forms, from monolithic pieces to nanometer¬
sized colloids, it is important to understand the effect of particle size on solubility. In
general, convex surfaces have a higher solubility, while concave surfaces have a lower
solubility. This effect, known as the Gibbs-Thompson effect, is described by the
Ostwald-Freundlich Equation
2 EV
S(r)=S¿e RTr
(2-3)
where S(r) is the solubility of a particle of radius r, S, is the solubility of a flat surface,

8
pil.
Figure 2-2. Solubility of silica in water at 25°C as a function of pH. Adapted from
Alexander et al. [Ale54|. Reprinted by permission of the American
Chemical Society.

9
E is the interfacial energy, V is the molar volume, R is the universal gas constant and T
is the absolute temperature.
For collections of small particles, points of particle-particle contact represent
regions of high negative curvature and will be preferred sites for deposition. Similarly,
small particles will dissolve due to their high radius of curvature and silica will deposit
at regions of negative curvature or on particles with larger radii, a phenomenon referred
to as Ostwald ripening.
Kinetics of Silica Dissolution and Deposition
Rimstidt and Barnes [Rim80| derived a general rate equation for the hydration and
dehydration of silica described in equation (2-1). Their work was based on the
assumption that reactants must form an activated complex of arbitrary composition as an
intermediate step during their conversion to products. Starting with the reactions
(2-4)
SÍO2 + 2H2O > (Si02-2H20)
(Si02-2H20)* <-» Si(OH)4
(2-5)
and assuming that reaction rate is proportional to the concentration of the activated
complex (denoted with an asterisk) they derived the following rate equation
(2-6)
where a¡ is activity of i, P is the pressure, T is the absolute temperature, A is the
interfacial area, M is the mass of water in system, y is the activity coefficient of i, k+ is
the dissolution rate constant and k is the precipitation rate constant. The parameters k+

10
and k were determined by measuring silica reaction rates at various temperatures and are
expressed as
logk = -0.707-^^ (2-7)
T
/og£+ =-0.369-(7.890 x 10-4)7-^p (2-8)
This set of equations expresses the observation that the rate of dissolution decreases as
the activity of dissolved silica (silicic acid) increases in solution. Dissolution rate also
is proportional to the ratio of silica surface area to solution mass. Thus, a high surface
area silica submerged in a limited amount of water will reach equilibrium more quickly
than a low surface area silica in a large solution volume. The area-to-mass ratio,
commonly expressed in glass corrosion literature as the surface area-to-solution volume
ratio (SA/V), is a critical parameter which dictates kinetics and sometimes corrosion
mechanisms. Important factors and their effect on silica-water reaction rates are presented
in Table 2-1.
Structure and Corrosion of Alkali-Silicate Glasses
Next we consider the slightly more complex case of silica doped with a modifying
group I alkali oxide, R20, where R = Li, Na, K. Introduction of alkali atoms into the
glass results in a decrease in the glass transition temperature and the aqueous durability
of the glass. These effects are related to the alteration of the atomic-level structure of
silica by the conversion of bridging oxygen, or siloxane (Si-O-Si) bonds, to non-bridging

11
Table 2-1. Factors that Influence the Rate
of Silica-Water Reactions
Variable
Effect on Reaction Rate
Valid Extrapolation Range
Temperature
Exponential dependence
0 - 300°C
Pressure
Very little effect
0 - 500 bars
Extent of System
Rate proportional to A,
inversely proportional to
M
(A/M) < 104
Activity of H2Si04
Rate proportional to (1-
Q/K). (Q = activity
product, K = equilibrium
constant for formation of
activated complex
At large Q/K high free
energy phases may
nucleate
Mechanism
Rate controlled by
breaking Si-O bonds
At low (A/M) nucleation
controls precipitation rate;
at T > 300°C diffusion
may control rates
Silica phase present
Determines K and
therefore Q/K
Valid for quartz,
cristobalite and
amorphous silica
pH
No effect
Slightly acid to neutral
systems
Salts
Reduce aH2D and thus
Si02 solubility
(?) No evidence of effect
on mechanism
Particle size
Small particles have
higher solubility
For particles < 0.1 qm, K
should be corrected for
surface free energy
Adapted from Rimstidt and Barnes |Rim80).

12
oxygen bonds (NBO), which are more susceptible to aqueous attack. In addressing the
issue of corrosion, the situation is now complicated by the effect of leached alkali ions
on solution composition and pH, as well as possible barrier effects of any silicious
material remaining behind on the glass surface. The problem now becomes that of
considering a non-equilibrium solid having a constantly changing surface composition
reacting with a solution of constantly changing pH and composition. The following two
sections will discuss the structure of binary alkali glasses as a function of composition
and examine leaching data and models which have been used to explain corrosion
mechanisms.
The Structure of Alkali Silicate Glasses
The basic structural unit of silica is the Si02 tetrahedron. Tetrahedra are joined
at their comers through bridging oxygen atoms (siloxane or Si-O-Si bonds). In order to
accomodate the introduction of R20, siloxane bonds are broken, the oxygen from R20
bonds to Si, and R+ atoms take up positions to charge compensate Si-O groups. Such
bonds are referred to as non-bridging oxygen bonds. In a study using magic angle
spinning nuclear magnetic resonance, Maekawa et al. [Mae91] measured the occurrence
of bridging and non-bridging oxygen in R20-Si02 glasses for compositions between 20
and 56 mol% R,0. Their results, summarized in Figure 2-3, express glass structure in
terms of Qn groups, where n designates the number of bridging oxygens per Si04
tetrahedron. The important point of this work is that binary glasses should

13
M2O /mol %
Figure 2-3. Experimentally determined Qn distributions in lithium (triangles), sodium
(squares) and potassium (circles) silicate glasses as a function of
composition. Adapted from Maekawa et al. (Mae91|. Reprinted by
permission of Elsevier Science Publishers.

14
be considered a mixture of Qn groups, rather than being comprised of only one or two
types of Q groups.
Corrosion of Alkali-Silicate Glasses
Many of the studies performed on the leaching of alkali-silicate glasses were
conducted in the early 1960s, before much of the current arsenal of analytical equipment
was available. As a result, most of the data developed on corrosion of these glasses is
based on the analysis of leachate solutions.
Charles [Cha58] and Budd [Bud61] described the corrosion of alkali-silicate glass
by water in terms of three reactions. The first reaction is essentially an ion exchange
process in which a proton, produced by dissociation of a water molecule, replaces an
alkali atom in the glass
=Si-0 +R + H20 =Si-OH + R+ + OH (2-9)
Hydronium or a hydrogen ion could serve as the reacting species rather than water.
Another possible reaction involves the attack by OH on bridging oxygen bonds
=Si-0-Si= + OH -> =Si-OH + =Si-0 (2-10)
The terminal O group created here is very reactive and may further interact with water
=Si-0 + H20 =Si-OH + OH (2-11)
As this reaction continues, Si may be progressively hydrated and removed from the glass
network, forming silicic acid.

15
It is also possible for terminal silanol (hSí-OH) groups to undergo condensation
to form siloxane bonds [Eil74]
=Si-OH + HO-Si= -> =Si-OSi= + H20 (2-12)
These reactions form much of the current basis of understanding of glass
corrosion. With this understanding of the reactions involved, Rana and Douglas
[Ran61a,b] produced what is considered the definitive work on the kinetics of alkali-
silicate corrosion.
Their study consisted of corroding crushed binary and ternary glass compositions
in a soxhlet extraction system in such a way that the glass was in contact with nearly pure
distilled water. Their analysis considered only the rate of appearance of glass constituents
in the leachate solution over the duration of the experiment.
In all cases, they observed two distinct leaching patterns. In the early stages of
leaching, the cumulative leached amounts of glass constituents increased with a t05
dependence. This was designated Stage I leaching. At later times, leaching showed a
linear time dependence, which was termed Stage II leaching.
Mathematically, Stage I was expressed as
Q(t)=a+kyft (2~13)
and Stage II was written
Q(t)=b+ct (2'14)
where Q(t) is the total amount of a given element released up to time t, a and b are
adjustable parameters, and k and c are rate constants.

16
Based on these results, they proposed a model in which alkali diffused out of the
glass by ion exchange, creating a silica-rich surface layer. Since this was a diffusional
process, a t05 dependence would be expected. However, the silica surface layer also is
subject to dissolution, and as the alkali removal rate is reduced due to the growing silica-
rich surface layer, a steady state is ultimately reached where both silica dissolution and
alkali removal proceed at the same rate.
Corrosion of Commercially Important Teman' Glasses
The binary glasses discussed previously are of generally low durability and of little
commerical importance. However, addition of a third component to these compositions
may drastically improve durability. The addition of approximately 10% CaO results in
a composition known as soda-lime-silica glass, which is the basis for most window and
container glass. Addition of 10%-30% B203 results in alkali borosilicate glass. Known
as Pyrex®, this extremely durable glass is used in laboratory and household applications
where resistance to aqueous corrosion is required. Alkali borosilicate glasses owe their
corrosion resistance in part to phase separation, in which an easily corroded sodium borate
phase separates from a more durable silica-rich phase. Leaching of these glasses is
entirely dependent upon the distribution of the soluble phase. If this phase occurs in a
non-interconnected fashion, the corrosion properties of the glass will be dictated by those
of the silica-rich phase, as is the case with Pyrex®; however, if the leachable phase
develops as an interconnected network, then it is entirely available for corrosion. In this
case, leaching will result in a porous, silica rich skeleton. This is the basis for the Vycor®

17
process which is used to manufacture nearly pure silica glasses at temperatures well
below the melting point of silica [Kin76],
Corrosion of Soda-Lime-Silica Glass
In early studies of soda-lime-silica glasses. Rana and Douglas [Ran61a,b] observed
that as Si02 was replaced by CaO in sodium-silicate glass, the glass became more durable
and the proportion of alkali to silica in the leachate approached their ratio in the glass,
suggesting that the corrosion mechanism had changed from one of selective removal of
alkali to one of congruent dissolution. Leached surfaces of this glass were still shiny and
showed no visual indications of alteration.
Soda-lime-silica glass leaching as a function of solution pH was studied by El-
Shamy et al. [E1S72] and by Smets and Tholen [Sme85], El-Shamy et al. found that
below pH 9 no silica was extracted and alkali extraction was independent of pH; however,
at pH values greater than 9, silica extraction increased while alkali extraction decreased.
In all cases extraction of calcium was negligible. At pH values less than 3, glasses with
greater than 10 mol% CaO demonstrated a much greater dissolution rate and calcium was
observed in the leachate. At these low pH values the ratio of extracted sodium to calcium
was the same as that in the glass.
Smets and Tholen |Sme85] examined the corrosion of 20Na2010Ca070Si02 in
buffered solutions at pH values from 4.5-13. Secondary ion mass spectrometry (SIMS)
analysis of the leached glasses indicated that calcium depletion was limited to the first 10
nm of the glass surface. Sodium depletion was deepest in acidic solutions (approximately

18
700 nm after 16 hours) and only 100 and 10 nm in solutions of pH 9.1 and 13,
respectively. Their results are compiled in Table 2-2. These results suggest that between
pH 4.5 and 9, corrosion is a combination of congruent dissolution (linear rate) and
diffusion-controlled leaching of alkali ions. At pH 13, the glass is leached almost
congruently, but very slowly.
A SIMS profile of a leached soda-lime-silica glass surface is shown in Figure 2-4.
This result, obtained from a 10Ca016Na2074Si02 glass [Ric84], shows a surface
depleted in Na, enriched in Si and a near-surface depletion of Ca with an enrichment of
Ca at deeper levels. This result is consistent with those obtained by other workers
[Cla76a, Sme85, Gos78].
Corrosion of Sodium Borosilicate Glass
Probably the most definitive work to date on the corrosion of sodium borosilicate
glass was performed by Bunker et al. [Bun88| who used Raman spectroscopy and nuclear
magnetic resonance spectroscopy (NMR) to characterize atomic-level structure in several
sodium borosilicate glasses before and after leaching at pH 1,9 and 12.
Raman spectroscopy of Na20 B20, Si02 glasses with component ratios of
30-10-60, 20-20-60 and 10-30-60 revealed significantly fewer non-bridging oxygen bonds
than would be predicted if all sodium were associated with NBO sites, indicating that
some sodium is associated with anionic, tetrahedral boron sites. In the 30-10-60 and
20-20-60 glasses Raman spectra indicated that borate structures were interspersed
throughout a silicate matrix, as evidenced by the presence of Si-O-B bonds. However,

19
Table 2-2. Dissolution Rates and Sodium Depletion Depths
for Soda-Lime-Silica Glass
Buffer
pH
Dissolution
Rate (nm/hr)
Sodium Depletion
Depth (nm)
h2o
5.8 - 6.1
<10
720 (16hr)
kh2po4
4.7 - 5.0
<10
670 (16hr)
k2hpo4
9.1 - 8.8
155
100 (16hr)
KOH
13.0 - 12.8
240
10 (lhr)
Adapted from Smets and Tholen [Sme85].

20
Figure 2-4. SIMS profile of 16Na2O10CaO74SiO2 leached 30 minutes at 85°C.
Adapted from Richter et al. [Ric84]. Reprinted by permission of
Revista Stazione Sperimentale della Vitro.

21
in the borate rich 10-30-60 glass no Si-O-B signal was detected. This suggests that the
glass is phase-separated and that borate groups tend to occur in borate rather than silicate
environments.
After the glasses were leached at pH 1 no non-bridging oxygen sites were found,
and the glasses contained substantially fewer silanol groups than would be predicted by
the conversion of NBO sites to silanols. This was taken to indicate that silanol
condensation had taken place. The leached material was nearly identical in composition
to silica, but differed from vitreous silica in that it was comprised of four-fold rings in
contrast to vitreous silica where higher order rings predominate.
For 10-30-60 glass leached at pH 9 and 12, Raman spectra were identical to that
of vitreous silica. A small proportion of Si-OH was found, and no 3- or 4-fold rings were
noted. The structure was composed of higher-order silica rings. Raman spectra of
30-10-60 and 20-20-60 glasses were unaffected by leaching at pH 9 and 12.
Nuclear magnetic resonance spectroscopy of 2ySi is capable of distinguishing the
local environment of silicon in terms of the number of bridging oxygen bonds (i.e. Q4,
Q3, Q2 and Q1 groups). In 30-10-60 glass prior to leaching, 75% of Si was present in Q3
groups and 25% in Q4 groups. After leaching at pH 1, 75% of Si existed in Q4 groups,
20% in Q3 groups and 5% in Q2 groups. The Q3 and Q2 groups terminated in silanol
groups rather than sodium, corroborating the results of Raman spectroscopy regarding
silanol condensation. No changes were noted in the glasses leached at pH 9 and 12 based
on NMR.

22
Acid leaching of 20-20-60 and 10-30-60 doubled the number of Q3 sites from 15%
NBO present initially to 30% silanols following leaching. In 10-30-60 glass leached at
pH 9 and 12, only Q4 sites were present after leaching.
Bunker’s group also examined the amount of ' O incorporated into silanol and
siloxane bonds from leaching in H2I70 labelled water. They found that l70 was
incorporated into Si-O-Si sites for all acid-leached glasses except 10-30-60, indicating
silanol condensation. The 30-10-60 glass leached at pH 12 was the only sample in which
NBO sites contained labelled oxygen and also had the lowest amount of l70 in Si-O-Si
sites. Analysis by 23Na NMR indicated that for all compositions studied, leaching at pH
1 resulted in the removal of all Na from the glass, while leaching at pH 9 and 12 did not
affect the sodium content.
Transmission electron microscopy of leached material showed that the leached
glass was comprised of a network of particles ranging in size from 10 to 160 Á in
diameter. Leaching under acidic conditions favored formation of small particles, while
basic conditions resulted in larger particles. BET surface areas ranged from 350 - 400
m2/g with pore diameters of <30 Á.
Bunker et al. concluded that the formation of silanol groups promoted the
hydrolysis of adjacent siloxane bonds, which resulted in the depolymerization and
dissolution of the silicate network. Simultaneously, silanol groups condensed, reforming
Si-O-Si bonds and repolymerizing the silica network, resulting in a leached layer similar
to colloidal silica. This behavior was used to rationalize the transition from tn 5 to t1

23
kinetics described by Rana and Douglas |Ran61a,b] as the result of a leached layer which
evolved with time from being protective into being nonprotective.
Corrosion of Nuclear Waste Glasses
Assessing the mechanisms of corrosion in nuclear waste glasses presents a
substantial technical challenge. These glasses were designed to optimize multiple
properties simultaneously [Wic85a, Sop83], They must be sufficiently durable to
immobilize radioactive waste for several hundred thousand years and be remotely
processed at temperatures sufficiently low to prevent evaporation of easily volatilized
components such as cesium. They must be insensitive to variations in waste stream
composition, be thermally stable against devitrification and have good mechanical
integrity. Glasses suitable for such applications contain numerous elements. The
composition of choice of U.S. defense waste applications, 165/TDS, contains 15 different
oxide components. The complexity of this material precludes most types of structural
analysis such as those described previously. However, an extensive empirical database
has been established for the corrosion performance of nuclear waste glass in both
laboratory and field environments |Tac90, Bra90, Sas90, Lod90, Ram90]. Significant
progress was made in the early 1980s by the Department of Energy-sponsored Leaching
Mechanisms Program [Men84] in elucidating general principles of corrosion in these
complex materials and delineating major characteristics of glass alteration layers. During
the last decade, three models have emerged which are capable of explaining and
predicting aspects of corrosion in nuclear waste glasses. These are the Savannah River

24
leachability model and the thermodynamic model, both developed at Savannah River
Laboratory, and the geochemical model, developed at the Hahn-Meitner Instituí in Berlin.
Characteristics of Nuclear Waste Glass Alteration Lavers
The Leaching Mechanisms Program, an intensive, multi-investigator research effort
[Men84], examined layer formation under a variety of leaching conditions. They
determined that altered glass tended to form highly structured, multi-layer structures
which had a sharp interface with the underlying glass. The alteration product retained the
dimensions of the parent glass but was of lower density. The degree of porosity varied
as a function of glass and leaching conditions, but all layers tended to have a honeycomb¬
shaped surface structure. Frequently, both crystalline and amorphous structures were
found at the surface. Layer compositions were depleted in soluble elements such as Na,
B and Li but retained the less soluble elements Si, Fe, Al, Mn, Ni, Ca and Mg.
These observations were combined into the surface layer schematic shown in
Figure 2-5. This diagram shows three layers typically seen in altered nuclear waste glass.
The reaction zone at the boundary between the main layer and the unaltered glass is
typically less than a micron thick and represents the advance of aqueous attack into the
glass. The main alteration layer is found beyond the reaction zone and may be several
microns thick. The precipitate layer is at the outer surface and consists of both
amorphous and crystalline deposits. More recent work [Lod89, Abr90| supports and

25
Figure 2-5.
H2SÍO3
Gel
Reaction
(Structured
Amorphous
Region)
Crystalline /Li-Saponite, \
Precipitates \Magnesite, CaC03/
Amorphous
Glass Reaction Zone
in Soluble Elements,
(B, Na, Li)
Schematic of alteration layer on a nuclear waste glass showing the reaction
zone, gel layer and precipitate layer. Adapted from Mendel [Men84],

26
extends the observation of layering. As many as six distinct layers have been observed
in some cases.
The Savannah River Leachabilitv Model
The Savannah River model, also known as the Wallace-Wicks model [Wal83,
Wic92], describes the effect on glass leach rate of a growing, semipermiable precipitate
layer on the glass surface. It is assumed that the glass leaches initially by an
interdiffusional process, followed by matrix dissolution. In addition to these reactions,
the SR model considers a third process—precipitation. As glass components are released
to solution, they may saturate and precipitate onto the glass surface, forming a barrier
which may or may not have a protective effect.
The model assumes steady-state conditions and that the rate of silica dissolution
at the glass-precipitate interface, Rdis, is equivalent to the rate of diffusion of silica
through the precipitated layer, Rdlf. Mathematically,
(2-15)
R^K(C,-C,)
«¿¡rffCo-O
(2-16)
where K is a rate constant, D is the diffusion coefficient of silica in the precipitated layer,
1 is the thickness of the precipitate layer and C, C0, and Cs are the silica concentrations
in the bulk leachate, the leachate within the layer immediately adjacent to the gel layer,
and a saturated solution, respectively.

27
If L is the amount of silica leached up to time t and q is an appropriate constant,
then 1 = qL and, since R = dL/dt, the above equations may be rearranged to yield
(2-17)
dt Z-pL
where p = Kq/D represents the silica dissolution from the glass and C/Cs represents the
degree of saturation of silica in the system.
If the system is closed then leaching products accumulate in solution and C/Cs =
aL where a = SA/V(l/Cs), SA is the glass surface area and V is solution volume.
Integrating 2-17 using the conditions that at t = 0, L = 0 the result is
(2-18)
a
In the case that the system is open and leach products do not accumulate then as V —> °°,
a —> 0 and
(2-19)
L+ -E- L2=KC t
2
These results are summarized in Figure 2-6 which plots the slope of a log-log plot
of silica release vs. time against the log of the reaction extent. Curve A shows that in the
early stages of leaching the slope is unity (congruent dissolution) and as the precipitate
layer forms the dissolution reaction becomes diffusion limited and the slope approaches
1/2. As saturation is approached (i.e. C/Cs —> 1), the slope approaches 0. Curve B

Slope
28
Reaction (log,0X)
Figure 2-6. Slope of logL vs. logt as a function of reaction extent based on Savannah
River leachability model. Curve A shows behavior in a system where
leaching is diffusion-controlled; Curve B shows saturation-controlled
leaching. Adapted from Wicks [Wic92]. Reprinted by permission of
Noyes Publishing Co.

29
demonstrates the effect of leaching at high SA/V where solution saturation effects stop
the corrosion process before a precipitate layer may form.
The Thermodynamic Model
The thermodynamic model of glass corrosion was developed by Plodinec and
Jantzen of Savannah River Laboratory [Plo84, Jan92] and is based upon the earlier work
of Newton and Paul [Pau77, Pau82], This model treats the glass as a mechanical mixture
of silicate and oxide components and assumes the overall free energy of hydration is
simply the sum of the free energy of hydration of the individual components. Calculation
of a composite Gibbs free energy of hydration is made by distributing modifying elements
into available silicates and treating glass-formers and leftover Si02 individually.
Mathematically,
A ^hyd~ GhJ)i
(2-20)
where AGhyd is the Gibbs free energy of hydration of the glass, x¡ is the mole fraction of
component i, (AGhyd)¡ is the Gibbs free energy of hydration of component i.
Since many glass corrosion reactions involve pH excursions, allowance has been
made for the dissociation of silicic and boric acid at high pH |Jan92). For H2Si03
A(AGM)=1.364
/
C-l
o
O
l
o
-log
1 + +
[ 10 p" 10 ^ 1)
(2-21)

30
and for H,BO,
A(AGM)= 1.364
-log
1 +
ip-9 !8 1Q 21.89 lQ-35.69^
10 pH 10 2pW 10 3pW „
(2-22)
Based on studies of over 300 glass compositions, Jantzen determined that a linear
relationship existed between the pH-corrected free energy of hydration of the glass and
the log of the normalized silicon mass loss from a 28 day MCC-1 |MCC83| leach test.
This is shown in Figure 2-7.
Jantzen's work is of particular importance in predicting the long-term performance
(~105 years) of nuclear waste glasses via thermodynamic correlation with naturally-
occurring glasses which are known to be stable in the environment on a geologic
timescale [Jan86, Ewi87].
Geochemical Modelling of Glass Corrosion
Computer modelling has been used to predict corrosion of mineral systems |Gra84,
Gra92| and was first applied to nuclear waste glasses by Bemd Grambow. This approach
treats congruent dissolution of the glass as a source term for entry of glass components
into solution. Once components enter solution, the model considers saturation and
precipitation and predicts the thermodynamically favored precipitation products and
corresponding solution concentrations. Because the model is thermodynamic in nature,
the occurrence of these processes is expressed as a function of reaction extent, rather than
time.

Si NORMALIZED MASS LOSS ( g / m
31
_ 10000,
1000,
100,
10,
0.14
LogSi“-0.1636G(hyd) + 0 3557
R2 = 0.73
3 ** J3y
4* 3
0 jpy
é
a
íj
a
/+ — a ©
a
10 5 0 -5 -10 -15 -20
FREE ENERGY OF HYDRATION ( kcal / mole )
Legend
A ACTUAL
* BASALT
O 80R0SIL
a CHINESE
a EGYPTIAN
x FRENCH
* FRITS
* CLCERAM
o granite
* HIGHSI
o ISLAMIC
a LUNAR
7 MEDIEVAL
a Mise
â–¡ MIXALK
A OBSIDIAN
x ROMAN
O SRL
a TEKTITE
B VENETIAN
x WASTE
Figure 2-7. Linear regression plot of over 300 leach tests relating AGhyd calculated
from glass composition and pH to log silicon release for 28 day static
leach tests. Adapted from Jantzen [Jan92]. Reprinted by permission of
Noyes Publishing Co.

32
In Grambow’s early work, he noted that for glasses leached in buffered solutions
at various pH values, the concentration of Ca++ behaved as though it were in equilibrium
with solid CaC03 [Gra82], Grambow later adapted a geochemical computer code
(PHREEQE) to model the formation of glass alteration products. The output of this
model is shown in Figure 2-8 and shows a close correspondence to measured values.
PHREEQE is also capable of accounting for the presence of reaction products from
corrosion of other parts of a waste package, such as the stainless steel canister.
The geochemical model considers the rate-limiting step in corrosion to be the
irreversible decomposition of an activated surface complex. The overall reaction rate of
the glass is given by the product of the concentration of the activated complex and a
decomposition frequency factor. The affinity of the reaction is given by the ratio of the
ion activity product in solution to the equilibrium constant for the reaction. According
to Grambow, the cessation of leaching in high silica solutions is due to saturation of the
solution with respect to the activated surface complex, rather than with respect to the
glass.

NORMALIZED CONCENTRATION
33
1 10 10' 10' 10*
REACTION PROGRESS, g- m'
Reaction of nuclear waste glass with 0.001 MgCl2 solution. Solid lines are
the result of modelling using PHREEQE. Data points are experimental
results. Adapted from Gram bow and Strachan [Gra84]. Reprinted by
permission of the Materials Research Society and Bemd Grambow.
Figure 2-8.

CHAPTER 3
OBJECTIVES AND ACCOMPLISHMENTS
The principal aim of this study was to evaluate mechanisms of glass corrosion
using a variety of surface and solution analytical techniques. This strategy was applied
first to simple binary alkali-silicate glasses leached in deionized water and is discussed
in Chapter 4. Information gained from study of this system was then applied to simulated
nuclear waste glass alteration in deionized water and "repository-relevant" leachants. This
is discussed in Chapter 5.
Specifically, the objectives of this work were to
1) develop and apply an integrated characterization methodology to study
composition, structure and microstructure in leached glasses
2) examine in detail the microstructure of glass alteration products
3) develop a model relating alteration product microstructure to glass leaching
mechanisms and kinetics.
As a result of this effort, three characteristic leaching phenomena were identified
in alkali-silicate glasses, based on analysis of microstructure and leaching kinetics. These
were
1) alkali removal with silica network preservation
2) congruent dissolution with precipitation of colloidal silica
3) congruent dissolution.
34

35
Based on these results, a model was proposed which explains the evolution of
these structures and the associated leaching kinetics. The model is based on
considerations of solution chemistry within the hydrodynamic boundary layer (HDBL)
adjacent to the glass surface and its effect on alteration product microstructure. The
validity of the model was confirmed by direct measurement of HDBL chemistry using a
novel sampling approach in order to obtain solution samples adjacent to the glass surface.
The methodology developed in this effort was further utilized to study the
alteration of simulated nuclear waste glass in deionized water, granitic groundwater and
synthetic brine. Studies of alteration product microstructure identified dissolution and
precipitation as the most likely mode of alteration. Diffusion-limited leaching kinetics
were identified in some cases and were explained based on saturation effects within the
pores of the alteration layer.

CHAPTER 4
STRUCTURAL, MICROSTRUCTURAL AND KINETIC ASPECTS
OF CORROSION IN BINARY ALKALI-SILICATE GLASSES
The objective of the work described in this chapter was to utilize surface analytical
tools to assess changes due to corrosion in R202Si02 (R = Li, Na, K) glasses. In
particular, microstructural alteration and its effect on leaching kinetics were examined.
Glass specimens were leached in flowing deionized water and analyzed by visual
inspection, scanning electron microscopy (SEM), transmission electron microscopy
(TEM), BET gas adsorption analysis and small-angle neutron scattering (SANS) to assess
microstructural features over five orders of magnitude, from approximately 10 Á to 100
|im. Leaching-induced changes in nearest-neighbor atomic structure were assessed using
Fourier transform infrared reflection spectroscopy (FTIRRS) and x-ray photoelectron
spectroscopy (XPS). Leaching kinetics were examined by measuring the rate of
appearance of glass constituent elements in solution using inductively coupled plasma
(ICP) spectroscopy.
Experimental
Alkali-silicate glasses were made by combining appropriate amounts of reagent-
grade alkali carbonates and silica and mixing them for a minimum of 24 hours in a jar
mill. Mixtures were melted in a platimum crucible in an electric furnace between 1200
36

37
and 1500°C for a minimum of 24 hours and cast into 1 cm x 1 cm x 5 cm bars.
Solidified bars were annealed at 500°C for one hour and allowed to furnace cool to room
temperature. Bars were stored in a desiccator until needed.
Individual glass specimens were cut from the cast bars using a low-speed diamond
saw. Bars of Li202Si02 and Na202Si02 glasses were cut into 1 cm x 1 cm x 0.2 cm
specimens; K20-2Si02 specimens were 1 cm x 1 cm x 1 cm. Samples were polished on
all sides using 400 and 600 grit silicon carbide paper, followed by 1 pm diamond paste.
Polished samples were wiped with a soft cloth and washed ultrasonically for 15 minutes
in ethanol, as specified by MCC protocol [Mat83]. Alcohol used in cleaning was replaced
with fresh ethanol at five minute intervals. Prepared specimens were stored in a
desiccator until used in corrosion studies.
Glasses were leached in teflon containers in flowing deionized water at 70°C,
similar to the MCC-4 test [Mat83]. Photographs of the corrosion system are shown in
Figure 4-1. Leachant flow rates and glass surface area-to-solution volume ratios (SA/V)
were controlled in order to maintain the pH as close to neutral as possible for each glass.
This is a particularly important aspect of the study, since accumulation of corrosion
products and pH excursions may impact both the mechanisms and kinetics of corrosion
|San73, Eth77, Wan58]. The duration of each study was adjusted to provide sufficient
leached layer for study and varied from six minutes in the case of the least durable glass
(K202Si20) to 35 days for the most durable glass (Li202Si02). Leachant flow rate,
residence time, SA/V, pH and test duration are shown in Table 4-1 for each glass studied.

38
Figure 4-1. Photograph of (a) corrosion system overview showing dionized water
reservoir, peristaltic pump, constant-temperature cabinet, leaching vessel
and collection bottle and (b) corrosion cell.

Table 4-1. Leaching Parameters for Binary Glass Studies
Glass
Flow Rate
(ml/min)
Residence
Time
(min)
SA/V
(cm1)
pH
Test
Duration
(min)
Li202Si02
1.8
34
0.27
9.7
49,000
Na20-2Si02
15
4.0
0.072
10.2
600
K202Si02
330
0.18
0.11
10.9
6.0
VO

40
Leachate samples were collected at appropriate intervals, acidified with nitric acid
[MCC83] and analyzed using ICP. At the conclusion of the leaching study, glass samples
were removed from the leaching vessel, rinsed in deionized water and transferred into
increasingly alcoholic mixtures of water and ethanol. Samples were hypercritically dried
under C02 [Lau86, Fil86| using ethanol as a transfer liquid. Hypercritical drying is a
particularly important (and largely neglected) aspect of corrosion sample treatment.
Drying in this manner avoids the formation of a meniscus in the pores of the leached
layer. Drying stresses are thus avoided and fine-scale microstructural features are
preserved [Sch90J. It was also found that samples dried in this way had better structural
integrity than those dried in air. Leached specimens were stored in a desiccator pending
analysis.
In addition to MCC-4-type testing, tests were conducted in a novel leaching cell
devised to permit separate, simultaneous solution specimens to be obtained from bulk
solution and the solution directly adjacent to the glass surface. This was accomplished
by adding a third port to the leaching flow cell described previously, as shown in Figure
4-2. Water was pumped into the cell through one port and allowed to flow out via the
second. Small-bore tubing was passed through the third port into the container and its
end firmly held against the glass surface. Water was very slowly pumped out of this port
in order to sample the solution at the plane where it contacted the glass.

41
Inlet
Surface
Figure 4-2. Corrosion cell modified to allow sampling at the surface of glass: (a)
photograph; (b) schematic.

42
Results
Visual Inspection
The macroscopic appearance of the glasses before and after leaching is shown in
Figure 4-3. Prior to leaching all glasses were transparent and clear. After leaching for
35 days, the Li20-2Si02 glass was clear and shiny, but contained numerous surface
cracks. These cracks began forming shortly after the glass had been removed from the
leaching solution and continued to form over a period of several days. The Na202Si02
glass was opaque and extremely delicate after 10 hours leaching. Mechanical integrity
was so low that several samples were destroyed during handling. Finally, the overall
appearance of K202Si02 glass was unchanged by leaching; however, the dimensions of
the sample were drastically reduced by leaching for approximately six minutes.
Scanning Electron Microscopy
Microstructure on the order of several millimeters down to approximately 0.05 pm
was examined using SEM. Specimens were examined both in cross-section (obtained by
fracturing the sample) and face-on.
Figure 4-4 shows an SEM of a cross-section of Li2O2Si02. The leached layer can
be easily discerned from the underlying glass. Large cracks and surface "channels" where
preferential dissolution has occurred are also visible. Higher magnification of this region
showed numerous small cracks throughout the layer. These cracks were not present in
the unleached glass.

43
Li20-2Si02 Na20-2Si02 K20-2S¡02
Unleached
Leached
Figure 4-3
Macroscopic appearance of binary glasses in leached and unleached states.

Figure 4-4.
Scanning electron micrographs of fracture surface of leached
Li202Si02: (a) 35x; (b) l.OOOx; (c) 35,OOOx.

45

46

47
The surface of leached Li20-2Si02 glass is shown in Figure 4-5. Cracks are
visible on the surface along with small pits and channels where preferential corrosion
appears to have taken place. It is significant that polishing scratches are still visible on
the surface, since this indicates that appreciable dissolution of the silica network has not
occurred.
Micrographs of a cross-sectional fracture surface of Na20-2Si02 are shown in
Figure 4-6. At low magnification it is clear that the leached layer has a very disrupted
microstructure, with numerous cracks and extensive pitting compared to the underlying
glass. High magnification in Figure 4-6c shows that, on a small scale, the altered glass
is not homogeneous but is composed of densely packed particles with diameters on the
order of 0.07 pm.
The surface of leached Na202Si02 is shown in Figure 4-7. The appearance of
this glass is drastically different from the Li2O2Si02 glass. Macroscopically, it is roughly
textured and opaque. Microscopically it has a structure which is dominated by large,
hemispherical pits. At high magnifications (Figure 4-7c) the pit edges show a terraced
structure. The mechanism of formation of these terraced pits is uncertain.
SEM examination of the leached K202Si02 glass, shown in Figures 4-8 and 4-9,
revealed an extremely thin (<(). 1 pm) reacted layer with no discemable microstructural
features. Some regions of layer formation on the order of 1 pm were found in places, as
noted in Figure 4-8b. This layer, when present, was cracked and partially separated from
the underlying glass.

Figure 4-5. Scanning electron micrographs of leached Li20-2Si02 surface
(a) 35x; (b) l,000x; (c) 35,000x.

49

50

Figure 4-6.
Scanning electron micrographs of fracture surface of leached
Na20-2Si02: (a) 35x; (b) 200x; (c) 35,OOOx.

52

53

Figure 4-7.
Scanning electron micrographs of leached Na20-2Si02 surface: (a)
35x; (b) 200x; (c) 600x.

55

56

Figure 4-8.
Scanning electron micrographs of fracture surface of leached
K20-2Si02: (a) 35x; (b) 30,000x.

58

Figure 4-9.
Scanning electron micrographs of leached K202Si02 surface: (a)
200x; (b) 750x.

60

61
Transmission Electron Microscopy
Small-scale microstructure, on the order of 5-500 nm was examined using
transmission electron microscopy (TEM). Specimens were prepared using a technique
described by Bunker et al. [Bun84] and Randall [Ran87] in which leached layers were
scraped from the glass using a diamond-tipped stylus into a container of 1,1,1
trichoroethane. Suspended particles were dispersed by high intensity sonication for 15 -
20 minutes. The resulting slurry was placed dropwise onto a warm formvar-coated
copper TEM grid, and the trichloroethane was allowed to evaporate.
Examination of Li202Si07 revealed numerous particles such as the one shown in
Figure 4-10. These particles had smooth surfaces and a reasonably homogeneous
microstructure on the scales studied here. Selected area electron diffraction (SAED),
shown in Figure 4-10b, showed diffraction rings, indicating some degree of crystallinity
in this material; however, x-ray diffraction analysis of the leached glass did not indicate
crystallinity, suggesting that the ordering found by SAED occurs on a small scale,
possibly as isolated crystallites.
In contrast, the leached Na202Si02 glass is roughly textured and appears to
consist of connected particles approximately 7-16 nm in diameter with void spaces in
between, as shown in Figure 4-11. SAED showed this material to be completely
amorphous. Leached K2O2Si02 was not examined, since it lacked sufficient layer for
study.

Figure 4-10. Transmission electron microscopic analysis of fragment of leached
Li20-2Si02: (a) bright-field image; (b) selected area electron
diffraction pattern.

£9

Figure 4-11. Transmission electron microscopic analysis of leached Na202Si02
fragment: (a) bright-field image; (b) selected area electron
diffraction pattern.

£9

66
Small Angle Neutron Scattering
Small angle neutron scattering (SANS) measurements were used to determine
microstructure correlation lengths and to investigate any fractal properties in the leached
material. All measurements were made on the 30-meter neutron scattering camera at the
National Center for Small Angle Scattering Research at Oak Ridge National Laboratory.
SANS is sensitive to structural inhomogeneities and is useful in the study of small-
scale microstructure. Scattering occurs as a result of neutron interaction with spatial
variations in the distribution of matter. In the case of leached glass, this variation is due
to the presence of silica and pore space [Tom83, Sch87, Sch89].
The central problem of SANS work involves determination of the structure
responsible for a given scattering pattern. Several models are available to address this
issue. The Debye-Bueche model |Deb49, Deb57, Lon74, Wig90] was chosen for this
work because it is applicable to a random, interpenetrating two-phase system and is
capable of determining correlation lengths in porous material. According to the Debye-
Bueche model, scattering curves may be described as
/«?)=-
2\2
(i+(?V):
qV
+A,e 4
(4-1)
where Q is the scattering vector, I(Q) is the scattering intensity at a given value of Q, A,
and A2 are fitting parameters and a, and a2 are con-elation lengths.
SANS has also been used extensively to probe fractal aspects of materials [Bal84,
Cra86, Hen90, Sch86, Sch89a, Sch89c]. A fractal object is one which displays "dilation
symmetry" or "scale invariance." This means simply that the object appears similar at

67
varying length scales. Coastlines, trees and river deltas are familiar examples.
Mathematically, such structures are characterized by a fractional dimensionality. Surface
fractals obey the relation
S~R
D,
(4-2)
where S is surface area, R is the object size and Ds is the surface dimension (Ds = 2 for
a smooth surface). Alternatively, an object is said to be mass fractal if it obeys the
relation
where M is the mass of the object, R is the object size and D is the fractal dimension.
Measurement of the fractal aspects of an object by small angle scattering
techniques is made possible by a power law dependence of scattering intensity vs.
scattering vector
m~Q
-2D*D,
(4-4)
where all variables have the same meaning as previously discussed. At large values of
Q, scattering is due to interaction with primary particle surfaces. This region of the curve
is known as the Porod regime and displays a -4 power law dependence for a smooth
surface. A fractally rough surface will result in a deviation from this behavior and will
display a power law exponent between -3 and -4.
At smaller Q values, collections of primary particles give rise to scattering. This
region of the curve contains information from larger microstructures and is known as

68
the Guinier regime. On this scale of measurement, the surfaces of the primary particles
appear smooth and power law exponents between -1 and -3 would be expected.
The scattering curve of leached Li20-2Si02 is shown in Figure 4-12. This sample
was a weak scatterer and required a 12-hour collection time to accumulate sufficient data.
The scattering curve is presented in two segments, since two camera lengths were used
to cover a larger range of Q. The region of the curve corresponding to the smallest scale
(Q values ranging from 1.25 to 0.25 nm ') shows no structure. At scattering vectors less
than 0.25 nm'1, results demonstrate power law scattering with an exponent of -4.24.
There is sufficient spread in the results that an exponent of -4.0 cannot be ruled out
within a reasonable confidence interval. This appears to be Porod scattering behavior,
indicative of smooth surfaces; however, the lengths being probed in this region correspond
to length scales of several hundred nanometers, which is considerably larger than a
primary particle. This data may be the result of scattering from the fracture surfaces
observed by SEM.
Figure 4-13 presents the scattering curve of leached Na202Si02. This curve
clearly demonstrates Porod scattering behavior from smooth particle surfaces at high
scattering vector values. At these values, length scales of a few nanometers are being
probed, corresponding to surfaces of the primary particles which were observed by TEM.
At intermediate Q values, the scattering exponent is approximately -1, and at the largest
Q values, a slope of -4.12 is observed. At large Q values, scattering is due to neutron
interactions with the surfaces of the 700 nm particles which were identified by SEM. No
clear surface fractal aspects were observed in any of the curves. However,

Log I
69
2.0
1.0 -
0.0
-1.0 -
-2.0 -
-3.0 -
-4.0
cfn
\
â– %
LL02SÍ0,
Efa
tn
DcP
dPc
â– a nm
â–¡ â–¡
â–¡
â–¡ tv, â–¡ i
D D □ “ m
â–¡ cn
â–¡ J
â–¡ â–¡
J I I I I I l I I I I I I I I I I L.
-1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2
Log Q (nm1)
Figure 4-12. Small angle neutron scattering curve of leached Li202Si02. The two data
segements are from different camera lengths. Low-Q portions of the
curves have slopes of approximately -4.24.

Log I
70
Figure 4-13. Small angle neutron scattering curve of leached Na20-2Si02. Slope in the
high Q region is approximately -4.0 and is -4.12 in the low Q region.

71
because of statistical variations present in linear curve fitting, small deviations from
integer dimensionality cannot be ruled out.
Further analysis of the Na202Si02 curve by Debye-Bueche methods detected
correlation lengths of 29 Á and 642 Á, which correspond approximately to the structure
scales observed by TEM and SEM, respectively.
BET Gas Adsorption Analysis
Results from BET nitrogen adsorption analysis of leached Na202Si02 indicate that
the surface area of a single sample increased from 7.26 cm2 for an unleached specimen
to approximately 80,000 cm2 after leaching, an increase of over four orders of magnitude.
These results are consistent with those of Walker [Wal77] for Bioglass® leached in 0.1M
TRIS buffer at 37°C. Pore size analysis is shown in Figures 4-14 and 4-15. Results
presented here have been normalized to the original geometric surface area of the glass
instead of the more traditional sample mass. This was done because both leached
surfaces and unleached interiors were present in these samples. Thus, these measurements
indicate the amount of pore volume present per unit of original geometrical surface area.
These results show a narrow pore size distribution centered around a diameter of 35 Á,
with a second, wider distribution ranging from 60 to 300 Á. Bunker et al. [Bun88] found
a similar distribution of pores under 30 Á diameter in studies of leached alkali
borosilicate glasses. Corrosion of Li202Si02 and K20-2Si02 did not produce sufficient
surface area to allow study by gas adsorption methods.

PORE VOLUME, cm3/cm
72
Figure 4-14. Cumulative desorption pore volume of leached Na20-2Si02 measured by
BET.

PORE VOLUME (x 106) cm3/cm2
37.4
3.4
30.6
27.2
Na2 0*2S¡02
dV
^5 Desorption
Pore Volume
PORE DIAMETER, (A)
Figure 4-15. Pore size distribution of leached Na20-2Si02 as measured by BET.

74
Fourier Transform Infrared Reflection Spectroscopy
Glass surface structure and composition were probed using specular reflectance
Fourier transform infrared spectroscopy (FTIRRS) |And50, Swe69, Ger87], Binary
glasses exhibit two broad reflectance peaks in the range of 800 to 1200 cm1. The peak
centered at 1050 cm 1 is due to linear vibrations of siloxane bonds. Non-bridging oxygen
(NBO) bonds give rise to the other peak at 975 cm 1 [San74, Cla77, Cla79, Che81,
Hus90]. Since modifier content correlates with the number of NBO sites in the glass, the
relative intensity of these two peaks is indicative of both structure and composition. In
addition, since a rough surface tends to scatter rather than reflect incident radiation,
decreases in the overall intensity of the spectrum indicate an increase in the degree of
surface roughening.
Spectra of leached and unleached binary glasses are shown in Figures 4-16 through
4-18. The spectrum of vitreous silica is also shown in each figure. In the case of
Li20-2Si02 glass, upon leaching, the NBO peak disappears, the bridging oxygen peak
intensifies, and the overall shape of the spectrum very closely approaches that of vitreous
silica.
Leached Na20-2Si02 shows very similar behavior; however the intensity of its
spectrum is much less than that of vitreous silica, indicating a rough surface. These
results demonstrate that the composition of the leached surfaces of Li20-2Si02 and
Na20-2Si02 are both similar in composition and structure to vitreous silica, due to the
formation of bridging oxygen bonds at the expense of NBO bonds during leaching.

REFLECTANCE
75
1400 1275 1150 1025 900 775 650 525 400
WAVENUMBER
Figure 4-16. FT1RRS spectrum of Li20-2Si02 before and after leaching. The spectrum
of vitreous silica is shown for reference.

REFLECTANCE
76
WAVENUMBER
Figure 4-17. FTIRRS spectrum of Na202Si02 before and after leaching. The spectrum
of vitreous silica is shown for reference.

REFLECTANCE
77
Figure 4-18. FTIRR spectrum of K20-2Si02 before and after leaching. The spectrum
of vitreous silica is included for reference.

78
The two glass surfaces differ, however, in that Na20 2Si02 is rougher and scatters more
strongly than Li202Si02.
FTIRRS measurements of K20-Si02 show that leaching has little effect on the
shape of the spectrum, demonstrating that the leached surface has a composition and
structure nearly identical to the unleached surface. However, the leached glass spectrum
has a lower intensity than the unleached glass, due to surface roughening.
X-ray Photoelectron Spectroscopy
Near-surface atomic structure was studied using XPS. XPS is sensitive to the
bonding state of a given element. Thus, it was possible to measure the binding energy
of Ols electrons in order to determine the relative proportions of oxygen atoms involved
in bridging and non-bridging bonds | Vea80,Spr901. Also, because XPS peak area is
proportional to concentration, it was possible to determine surface concentrations of each
glass element based on Ols, Si2p, Li Is, Nakll and K2p peaks.
Since this technique measures only the outer few atomic layers, and because
simple exposure to atmosphere is sufficient to induce changes in this region of the glass,
unleached glasses were fractured in the vacuum chamber of the XPS system to provide
a fresh, unreacted surface for analysis. Leached samples were examined in "as received"
condition.
The binding energy distribution of the Ols electron is shown in Figure 4-19 for
unleached and leached Li20-2Si02 glass. Peaks from bridging and non-bridging oxygen
bonds are not completely resolved in these spectra and appear as an asymetry in the

79
BINDING ENERGY
BINDING ENERGY
Figure 4-19. XPS of 01s line of Li20-2Si02 glass: (a) unleached; (b) leached.

80
overall band. The individual contributions of each type of bond have been resolved by
fitting Gaussian distributions to the composite curve. In XPS, peak area scales with
concentration so the relative amounts of each type of bond may be determined. A
contribution from NBO bonds clearly can be seen in the spectrum of the unleached glass.
After leaching this contribution is lower, and the spectrum is dominated by the lower
binding energy peak. Virtually identical results were obtained for the Na202Si02 glass,
as shown in Figure 4-20.
In the case of K20-2Si02, shown in Figure 4-21, the Ols spectrum of the leached
sample is very similar to that of the unleached sample. The NBO peak has lost only a
small portion of its area as a result of leaching. This suggests that surface alteration
leaves a leached surface very nearly identical in structure and composition to that of the
unleached surface. Surface compositions of leached and unleached samples were also
determined [Esc75] and are summarized in Table 4-2.
Leachate Analysis
The rate at which glass component elements appear in solution provides insight
into the mechanism and rate of reactions occuring at the glass surface. The leach rates
of silicon and lithium from Li2O2Si02 are shown in Figure 4-22. Small amounts of
silicon appeared in solution during the first few sampling intervals but rapidly fell below
the detection limits of ICP. The leach rate of lithium decayed rapidly over the first few
days of the study. Since these glasses contain equimolar amounts of modifier and silicon,
preferential or congruent dissolution may be assessed by comparing the leach rates of

81
538 536 534 532 530
BINDING ENERGY
Figure 4-20. XPS of Ols line of Na20-2Si02 glass: (a) leached; (b) unleached.

82
538 536 534 532 530
BINDING ENERGY
Figure 4-21. XPS of Ols line of K202Si02 glass: (a) unleached; (b) leached.

83
Table 4-2. Surface Composition Determined by
X-Ray Photoelectron Spectroscopy
Sample
O
atomic%
Si
atomic%
R
atomic%
Li20-2Si02
Unleached
57
23
20
Li20-2Si02
Leached
69
28
3
Na202Si02
Unleached
53
26
21
Na20-2Si02
Leached
65
27
8
K20-2Si02
Unleached
56
20
24
K20-2Si02
Leached
64
17
19
Si02
68
32
—

LEACH RATE (mol/m2 • d)
84
CORROSION TIME (min)
Figure 4-22. Leach rates of Li and Si from Li20-2Si02 during a 35-day corrosion test.
Data points are measured leach rates. Solid line is fit to Q = at0535.

85
the two elements. If the glass were dissolving congruently, the leach rates of the two
elements should coincide. A difference in leach rates between the two components
indicates selective leaching. Based on this explanation, it is clear that lithium is
selectively removed from this glass.
The overall shape of the lithium leach rate curve suggests a diffusion-limited
process, like that proposed by Rana and Douglas |Ran61a,b], To test this possiblity, data
were fit to equation 2-13 by plotting logQ vs. logt and determining the slope, which is
predicted to be 0.5 for a diffusion-limited process. This plot is shown in Figure 4-23.
Data taken at later times are linear and have a slope of 0.535, an intercept value of
0.00525 mol/m2, and a correlation coefficient of 0.999, indicating a high quality fit. It
was noted that data obtained at short times are not linear and have a slope greater than
0.5. This deviation from t0^ behavior may be explained by mixing effects within the
leaching cell and the fact that the time required for sampling is long compared to the rate
of change of the glass leach rate at early times in the experiment. Within the first few
hours of the test, the glass leach rate is changing rapidly during the 30-minute sampling
interval. Thus, solution analysis is measuring a weighted average of glass leach rate over
the course of the sampling time, resulting in skewed data. To test this hypothesis, a
simple BASIC computer program was written to calculate the solution values which
would be measured throughout the experiment, based on mixing and sampling effects and
assuming a leach rate based on parameters measured at long times where logQ vs. logt
was linear. The predicted results are plotted in Figure 4-22 along with the data and show
a very close match. For this reason, it is concluded that the glass leached with a t0'535
time dependence throughout the study.

log Q (mol/m¿)
86
Figure 4-23. Logarithmic plot of cumulative amount of lithium leached from glass vs.
time. The slope of approximately 0.5 indicates a diffusion-limited process.

87
Leaching results for Na202Si02 are presented in Figure 4-24. This graph shows
that after an initial mixing transient, sodium is removed from the glass at a nearly
constant rate. Silicon, however, is very slow to appear in solution, but after
approximately 30 minutes, its leach rate rises rapidly to approximately 9.5 molm'2-d 1 and
then gradually increases further until it matches the sodium leach rate. Thus, leaching is
initially by selective removal of sodium and ultimately evolves to congruent dissolution.
These results do not correlate with any established kinetic model.
Leaching of K20-2Si02 is shown in Figure 4-25. In this glass, silicon and
potassium appear in solution at the same rate, indicating congruent dissolution. This
figure also shows that leach rate is nearly constant over the duration of the experiment.
Surface/Bulk Solution Studies
In a few instances has it been recognized that solution conditions immediately
adjacent to the surface of a corroding glass may differ from conditions in the bulk
solution [Cla83, Sal84, Gra86, Bun88, Wic92, Gra92J. This issue is particularly
important, since it is the solution within the hydrodynamic boundary layer (HDBL) which
reacts with the glass. To date, no direct measurements have been made on this
hypothetical entity. Obtaining such measurements was the objective of this particular
portion of the work.
Samples were obtained at early leaching times from both the bulk solution and
also from solution next to the glass surface as described previously. Solutions were
analyzed for pH and glass constituents. The results of these analyses are summarized

88
Figure 4-24. Time dependence of the leach rates of Na and Si from Na2O2Si02 glass.

89
CORROSION TIME (min)
Figure 4-25. Time dependence of the leach rate of K and Si from K202Si02.

90
in Table 4-3. In this table, surface values are expressed as the minimum value for that
parameter, since the measured values are a function of sampler flow rate. Ideally, such
a sample should be collected infinitely slowly to avoid dilution by the bulk solution.
Since this is not practical, it is likely that the true values were reduced somewhat by
dilution from non-ideal sampling; therefore, the figures presented here represent a lower
limit to the actual value.
As shown in Table 4-3, the difference between conditions in the bulk and surface
solutions is greatest in the K2O2Si02 glass, which corrodes most rapidly, followed by
Na20-2Si02. Measurements of Li20-2Si02 show the smallest difference between surface
and bulk values.
Summary. Model and Discussion
Corrosion of Li,Q-2SiO,
This glass proved to be the most durable of the three compositions studied.
Polishing scratches, still visible on the glass surface after corrosion, demonstrate that the
silica network was not significantly disrupted during corrosion. XPS spectra show that
lithium is depleted at the glass surface, and infrared reflection spectra indicate that the
corroded surface is similar in structure to vitreous silica. The numerous cracks which
formed during drying suggest that silanol condensation occured, since this is known to
result in tension and subsequent cracking in the leached surface |Bun83, Bun88].
Microscopic studies using SEM and TEM showed that the alteration layer had a
homogeneous structure but with numerous cracks. This sample was a weak neutron

Table 4-3. Surface and Bulk Solution Values
Glass
P^Sllrf
1 ^ 1 surf
(mol/1)
l^Hsurf
(mol/1)
pHbuik
[^]bulk
(mol/1)
fSUbulk
(mol/1)
Li2O2Si02
>9.7
>9.0 x 10'4
>2.6 x 10'5
9.8
6.0 x 10‘4
1.6 x 10’5
Na20-2Si02
>10.5
>6.6 x 104
>4.9 x 10'4
10.0
3.1 x 104
1.9 x 104
K202Si02
>11.4
>2.3 x 10'2
>1.7 x 10'2
10.7
2.3 x 10'3
2.0 x 10'3

92
scatterer and demonstrated what appeared to be Porod scattering from surfaces on the
scale of several hundred angstroms. The surface area of the leached specimen was too
low to measure using BET techniques. Finally, solution analysis established that removal
of lithium from this glass obeyed diffusion-limited kinetics, with the lithium-depleted
silica surface acting as a diffusion barrier.
Corrosion of Na,O2Si02
Corrosion of Na20-2Si02 results in a morphologically disrupted surface layer with
a rough, pitted structure on the scale of several tens of microns. Examination of this
layer at higher magnifications revealed particles on the order of 0.1 (im, and at higher
magnifications, these particles were observed to consist of interconnected particles 7-16
nm across, with substantial inter-particle porosity. The minimum primary particle
diameter of 7 nm is of particular significance in terms of particle solubility. According
to the Ostwald-Freundlich equation (equation 2-3), 4 nm is the minimum radius of
curvature at which particle size ceases to be a factor in silica solubility. As particle
radius drops below this value, solubility increases exponentially. This suggests that the
observed structures are the result of a precipitation process from a saturated solution. The
existence of interparticle necks indicate that Ostwald ripening has taken place, depositing
silica at regions of negative curvature. BET surface area and porosimetry analysis
showed a surface area increase of four orders of magnitude and a bimodal pore size
distribution with a very narrow contribution centered around 35 A and a broad
distribution from 60-300 Á, consistent with the range of particle sizes observed by SEM

93
and TEM. These specimens were very strong neutron scatterers, with correlation lengths
of 29 and 642 Á, corresponding to small- and larger-scale structures. The results of
microstructural characterization by these independent techniques clearly demonstrates that
structure exists on two size scales in this material. Large-scale structure is comprised of
-700 nm particles which, in turn are a collection of interconnected 7-16 nm diameter
silica particles.
Compositional analysis by XPS indicated a small percentage of residual sodium
in the leached glass, although the number of NBO bonds was significantly reduced.
Infrared reflection spectra showed that the surface was structurally similar to vitreous
silica but with a great deal of surface roughness, consistent with results expected for a
highly condensed silica network.
This glass showed unusual leaching kinetics in that sodium was leached at a nearly
constant rate, suggesting that a diffusion barrier was absent; however, silicon showed only
a slight presence in the leachate during the first 30 minutes of corrosion. After this
period, however, the rate of appearance of silicon in the leachate dramatically increased.
After 10 hours leaching time, the rate of appearance of silicon was equal to that of
sodium, suggesting congruent dissolution.
Considered together, these results indicate that alteration of Na20-2Si02 occurs by
congruent dissolution, followed by precipitation of silica. Experimental findings are
explained by the following scenario. Initial corrosion is by ion-exchange of IT with Na+
in the glass, raising the pH of the solution adjacent to the glass. The resulting silanol-
bearing silicon atoms, which are more susceptible to corrosion than fully networked

94
silicon atoms [Bun88], are progessively hydrated and pass into solution. If this occurs
rapidly, sodium and silicon concentration within the HDBL adjacent to the glass will
increase, along with pH. If diffusion of dissolved glass components from the HDBL into
the bulk solution is not sufficiently rapid, silica will reach solubility limits within the
HDBL and precipitate, forming colloids. Colloids formed within the HDBL would be
unstable for two reasons. First, based on Darjaguin-Landau-Veowey-Overbeek (DLVO)
theory [Eve88], colloid double layers would be compressed due to the high ionic strength
of the surrounding solution. This would decrease electrostatic repulsion between particles
and allow a sufficiently close approach to permit attractive forces to dominate, leading
to particle contact and interparticle bonding. Also, according to Eiler [Eil74] and others
[A1169, A1170, A1171, Wat70], monovalent cations (particularly sodium and lithium) are
capable of adsorbing onto silica surfaces by replacing the hydrogen atom of a silanol
group, suppressing surface charge originally due to the replaced hydrogen, and permitting
close approach of colloids. Lee |Lee86] noted that the presence of sodium in solution did
not affect boron or lithium leach rates from a simulated nuclear waste glass, but it did
decrease the rate of appearance of silicon in solution, suggesting that more silicon may
have been tied up in colloidal precipitates. Either or both of these coagulation
mechanisms may be active during the alteration process. The microstructure of this
material suggests that its formation is a two-step process. The first step involves
formation, coalescence and Ostwald ripening of 7-16 nrn particles. These collections of
particles then grow to form the 700 nm particles which agglomerate and form the surface
layer.

95
Increases in the rate of appearance of silicon in solution at later leaching times
may be the direct result of the formation and growth of this porous surface layer. As this
thick, microporous layer forms, diffusion of dissolved glass components from pore water
to bulk solution becomes even more restricted than in the HDBL, since now glass
components must migrate through relatively small, tortuous pathways. Accumulation of
glass components within this region could result in pH values within the pores which are
sufficiently high to prevent the precipitation of silica dissolved from the glass, allowing
it to pass through the layer and into the bulk solution without undergoing precipitation.
Corrosion of K202Si02
Corrosion of K202Si02 occurs mainly by congruent dissolution and results in
drastic reductions in specimen size. Based on SEM analysis, only very thin, transient
leached layers are formed on this glass. Surface composition changed only slightly upon
leaching, with a small reduction in the number of bridging oxygen bonds. No leaching-
induced structural alteration was indicated by FTIRRS. Congruent dissolution was
confirmed by solution analysis, which showed that both K and Si leached at identical
rates.
A Model for Corrosion in Binary Alkali-Silicate Glasses
Data developed in this study represent a broad range of corrosion processes,
ranging from the total preservation of a silica surface in the case of Li202Si02, to
congruent dissolution followed by silica precipitation in Na202Si02, to congruent

96
dissolution in K202Si02. Measurements of leaching kinetics and mechanisms in this
work are drastically different from those observed by Ethridge [Eth77], Because Ethridge
studied static corrosion, his results reflect the interaction of glass with a high pH solution
containing glass corrosion products. In the present study, glass corrosion products were
not allowed to accumulate in the system, thus permitting the fundamental corrosion
processes to be isolated from secondary reactions due to corrosion product accumulation.
The results of this study may be explained and unified by consideration of the alkali leach
rate and its effect on the pH within the HDBL. As demonstrated here, there is
considerable difference in pH and concentration values between the two solution regions.
As determined in this study, Li20-2Si02 has an intrinsically low leach rate and
does not experience a sufficient pH rise within the HDBL for the glass silica network to
be attacked. As a result, the silica network is preserved and is able to function as a
diffusion barrier to further lithium migration. Intermediate behavior is shown by
Na20-2Si02, where the pH within the HDBL is high enough to dissolve the partially
hydrated silica network of the glass, but low enough to permit dissolved silica to
precipitate as colloids. The presence of sodium ions facilitates particle agglomeration.
Finally, the extremely rapid leaching found in K,0-2Si02 causes a sufficiently high pH
within the HDBL such that silica is unable to precipitate. Consequently, no alteration
layer is formed. Glass surfaces and relevant solution parameters are shown schematically
in Figure 4-26.

97
NagO^SiC^
(b)
highly porous Si02
pH=10.5
Y [Na]=0.0007M
bulk solution
pH=10.0
[Na]=0.0003
Figure 4-26. Schematic of leached glass surfaces, HDBL and bulk solution values for
(a) Li20-2Si02; (b) Na202Si02 and (c) K202Si02.

CHAPTER 5
AQUEOUS ALTERATION OF 165/TDS
SIMULATED NUCLEAR WASTE GLASS
Introduction
This study was conducted in order to provide an evaluation of 165/TDS simulated
nuclear waste glass utilizing the methodology and knowledge gained from studies of
binary glasses. Nuclear waste glass was leached in deionized water, granitic groundwater
and a simulated rock salt brine. These latter two leachants were present in burial studies
of this glass conducted under conditions representative of anticipated repository
environments. The inclusion of these leachants in this study permitted comparison of
laboratory data with field-leaching results.
Laboratory-leached glasses were studied using SEM, TEM and thermoporometry
to determine the microstructure of the glass alteration product. FTIRRS was performed
to qualitatively evaluate the extent of surface alteration and secondary ion mass
spectrometry (SIMS) was used to determine compositional depth profiles. FTIRRS and
SIMS were used to compare laboratory- and field-leached glasses. Finally, kinetics of
leaching were determined by ICP analysis of leachate solutions.
It was found that corroded nuclear waste glass demonstrates compositional and
microstructural characteristics consistent with material precipitation from a saturated
hydrodynamic boundary layer.
98

99
Experimental
Glass Processing and Composition
Glass composition 165/TDS was designed to immobilize Savannah River Plant
high level waste (HLW) [Sop83] and is the composition developed for use at the Defense
Waste Processing Facility (DWPF) at the Savannah River Site. All 165/TDS laboratory
specimens used in this study were prepared at UF using crushed glass which was supplied
by Savannah River Plant. Crushed glass was melted in a platinum crucible at 1173°C for
24 hours, cast into an appropriate size graphite mold, annealed for one hour at 500-525°C
and furnace cooled.
Specimens were cut into 3 cm diameter x 0.8 cm thick and 1 cm diameter x 0.3
cm thick cylinders, and 1 cm x 1 cm x 0.2 cm rectangular slices. All samples were
polished to 600 grit using silicon carbide paper, followed by 6 pm diamond paste.
Specimens intended for SIMS analysis were further polished with 1 pm diamond paste.
All samples were cleaned and stored as described in Chapter 4.
Compositions used in the laboratory and the burial studies are given in Table 5-1.
The composition of 165/TDS was slightly altered following the Stripa burial study, as
indicated by the designations "old" and "new.”
Leachants
Glasses were leached in deionized water, granitic groundwater and a magnesium
chloride-based brine (W1PP-A brine). Granitic groundwater was obtained from the

100
Table 5-1. Composition of 165/TDS
Simulated Nuclear Waste Glass
Component Mole %
Old New
Si02 53.41 58.36
B203 6.63 6.36
Zr02 0.39 0.65
Al263 1.71 2.59
Zeolite 0.39
Na20 10.56 10.77
Li20 10.76 10.18
MgO 1.12 1.30
CaO 1.18 1.75
Na2S04 0.07
SrC03 0.07
U308 0.07
CsN03 - 0.06
Sr(N02)2 - 0.06
NiO 1.38 0.78
Fe203 5.51 4.99
Mn02 2.95 2.14
Coal 3.81
Adapted from Zhu [Zhu86a].

101
Stripa mine in central Sweden. Stripa was the site of a previous burial study and has a
predominately granite geology. Typical composition of Stripa groundwater is given in
Table 5-2.
WIPP-A brine is a synthetic brine whose composition is designed to approximate
that of fluid inclusions found in rock salt (the geology found at the Waste Isolation Pilot
Plant (WIPP)). This composition of brine was used to backfill sample boreholes in the
Materials Interface Interaction Testing program (MIIT) at WIPP. This brine is made by
dissolving 584.2 g MgCl2-6H20, 200.2 g NaCl, 114.4 g KC1, 12.4 g Na2S04, 3.9 g
Na2B4O710H2O, 3.32 g CaCl2, 1.92 g NaHC03, 1.04 g NaBr, 0.25 g LiCl, 0.055 g RbCl,
0.03 g SrCl-6H20, 0.026 g KI, 0.025 g FeCl3-6H20, 0.25 ml concentrated HC1, and
0.0025 g CsCl in 2.0 liters of deionized water [Mol86].
Leach Tests
Glass was leached using a "pulsed-flow" test method developed at Catholic
University of America [Mac82], This method calls for leaching the glass in a closed
teflon container. Periodically, the container is opened, an aliquot of solution is removed
and an equal amount of fresh leachant is introduced. This method is useful for simulating
flow rates that are too low to be achieved using a peristaltic pump. A corrosion cell,
sample holder and glass samples are shown in Figure 5-1.
In this study, glass surface area varied from 52.06 to 45.10 cm" and the leachant
volume was 260 cm3. All tests were conducted at 90°C. Fifty milliliters of leachant was
exchanged weekly for six months.

102
Table 5-2.
Composition of Stripa Groundwater
Ion
Concentration (mg/1)
HC03
Cl
so4
Ca+
Fe3+
Mg2+
K+
Si02
Na+
15.4 - 78.7
52 - 283
I.9 - 2.7
10 - 59
0.02 - 0.24
0.5
0.2 - 5.4
II.0 - 12.8
43 - 125
Adapted from Zhu |Zhu86a].

103
Figure 5-1.
Teflorr corrosion cell, sample holders and nuclear waste glass specimens
used in the laboratory corrosion studies.

104
A total of eight tests were conducted. Four tests used deionized water as a
leachant, two used granitic groundwater and two used WIPP-A brine. Each test contained
two high surface area specimens for thermoporometry and several smaller specimens to
be used for SEM, TEM, FT1RRS and SIMS. At the conclusion of the test all specimens
were rinsed in room temperature deionized water. Specimens for thermoporometry were
kept wet and their surface layers were removed for study. The remaining specimens were
rinsed thoroughly in ethanol and hypercritically dried in C02. Dried specimens were
stored in a desiccator pending analysis.
Field Leaching Studies
Field leaching studies of 165/TDS have been carried out for periods of two and
five years in granite and salt, respectively. Referred to as in situ or burial studies, these
tests are designed to study wasteform performance under conditions closely approximating
actual repository conditions and involve maintaining the wasteform at elevated
temperatures (90°C) for extended periods within a burial environment.
The Stripa burial study was conducted in a granite environment in central Sweden
and was a joint effort of Savannah River Laboratory, the University of Florida and the
Swedish Nuclear Fuel Supply Co. A later test, the MIIT study, utilized the salt
environment of WIPP near Carlsbad, NM. Experimental details and results from both
studies are extensively documented in the literature |Lod86, Lod90, M0I86, Wic88,
Wic92, Zhu86a, Zhu86b, Zoi89, Wic85b, Wic86, Wic87, Wic88, Wic89, Cla89, Lod89,
Ver89, Jer89, Sas90, Bra90, Ram90, Tac90].

105
The essential feature of both tests is the burial assembly shown in Figure 5-2.
This assembly permitted pineapple-slice-shaped glass samples to be interfaced with
samples of candidate canister materials, geology samples (salt, granite, bentonite, etc.) or
other glass specimens. At appropriate time intervals the assemblies were retrieved and
samples distributed to test participants for analysis. The burial specimens were both
obtained after two-years burial and are from glass/glass interfaces.
Results
Scanning Electron Microscopy
Surface morphology of the alteration layer formed after six months exposure to
deionized water is shown in Figure 5-3. This material appears to consist of a scattered
precipitate overlying a structure comprised of 1 pm-diameter spheres. This layer tended
to separate from the underlying glass and thus it was possible to examine the morphology
of the layer where it contacted the glass, as shown in Figure 5-3c. This portion of the
layer consists of nodules similar to those found at the surface, suggesting that this
structure persists throughout the layer.
The alteration layer formed in granitic groundwater has a much smoother
appearance, with some surface deposits of calcium-rich material, as shown in Figure 5-4.
Also, several large crystals were noted as shown in Figure 5-4b. These crystals were also
calcium-rich and are probably CaC03, formed from the reaction of calcium in solution
with dissolved C02. High magnification examination of the surface layer showed it to
be composed of numerous filaments like those shown in Figure 5-4c.

106
CRUSHED
SALT
PACKING
BRINE
INJECTION
TUBE
TEFLON
THREADED
ROD
TEFLON
NUTS
TEFLON
DISK
[NOT TO SCALE]
^—^PLUGGED
SAMPLING
1 - PORT
TEFLON
HOLE
SHEATH
THERMOCOUPLE
NO. 1
THERMOCOUPLE
NO. 2
TEFLON
ALIGNMENT
DISK
10 cm
Figure 5-2. Materials Interface Interaction Testing (MIIT) assembly used for field
studies of nuclear waste glass corrosion at the Waste Isolation Pilot Plant.
A similar sample configuration was used in the Stripa study. Adapted
from Molecke [Mol89]. Reprinted by permission of Martin A. Molecke.

Figure 5-3. Scanning electron micrographs of 165/TDS simulated nuclear waste glass
leached in deionized water: (a) surface, 3000x; (b) surface, 15,000x; (c)
underside of flaked piece, 15,0()0x.

108

109

Figure 5-4. Scanning electron micrographs of 165/TDS simulated nuclear waste glass
leached in granitic groundwater: (a) surface morphology showing
precipitates, lOOOx; (b) calcium-rich crystalline surface deposit, 140x; (c)
alteration layer surface, 50,()()0x.

Ill

112

113
The surface of the brine-leached sample is dominated by magnesium-rich platelike
structures, shown in Figure 5-5a. Numerous large crystal formations were found on this
specimen as shown in Figure 5-5b.
Transmission Electron Microscopy
Alteration layers formed in deionized water and granitic groundwater were
examined using TEM. Sample preparation methods were identical to those described in
Chapter 4. Both specimens showed a heterogeneous microstructure at small scales.
Figure 5-6 shows a micrograph of the alteration layer formed in deionized water.
Details visible at the edge of the sample reveal the presence of individual particles,
approximately 4-5 nni in diameter. A corresponding view of the glass alteration product
formed in granitic groundwater is shown in Figure 5-7. This material shows a similar
particulate structure, along with needle-like or fibrous material. Brine-leached specimens
were not studied, due to their extremely thin surface layers.
Thermoporometry
Pore size analysis of leached nuclear waste glass poses numerous technical
challenges. Because this glass is quite durable, it is difficult to produce sufficient
material for BET analysis. In addition, stresses resulting from drying may alter the
material microstructure and impact measurements.
These difficulties were circumvented by utilizing a novel porosimetric technique
based on measurement of the freezing point depression of water contained in pores

Figure 5-5. Scanning electron micrographs of 165/TDS simulated nuclear waste glass
leached in WIPP-A brine: (a) magnesium-rich surface, l(),0()0x; (b)
magnesium-rich crystal on layer surface, 2,500x.

115

116
Figure 5-6. Transmission electron micrograph of 165/TDS leached in deionized water.

117
Figure 5-7.
Transmission electron micrograph of 165/TDS leached in granitic
groundwater.

118
[Bla72, War86], Known as thermoporometry, this technique requires only 20 mg of
material and is performed on wet samples. Since freezing point varies as a known
function of pore size (Qui86, Bru77], it is possible to use extremely sensitive differential
scanning calorimetry measurements |Qui88| to determine the quanitity of pore water
freezing at a given temperature, and from this to determine the volume of pores of a
given size. This technique has been widely applied to the characterization of wet silica
and aerogels [Qui85, Rou89],
The pore size distribution of 165/TDS leached in deionized water is shown in
Figure 5-8. This glass has a bimodal pore size distribution, with a narrow peak centered
at a radius of approximately 23 Á and a broader distribution between 80 and 1000 Á.
Very similar results were obtained for the sample leached in granitic groundwater, shown
in Figure 5-9. However, in this sample the upper portion of the bimodal distribution is
more limited than that of the deionized water-leached specimen, extending between 80
and 250 Á.
Fourier Transform Infrared Reflection Spectroscopy
Application of FTIRRS to the corrosion analysis of nuclear waste glass follows
most of the principles discussed in the preceeding chapter; however, due to the
complexity of nuclear waste glass, interpretation of spectra is not straightforward. It has
been observed in previous studies [Zhu86a, Zhu86b, Zoi89, Cla89) that in the early stages
of corrosion, the reflectance peak shifts to higher wavenumbers. At later stages, the
reflectance band decouples into two peaks. These effects are taken to be qualitative

119
R (nm)
Figure 5-8. Pore size distribution of 165/TDS leached in deionized water, as
determined by thermoporometry: (a) structure up to 4 nm; (b) structure
beyond 4 nm.

120
R (nm)
R (nm)
Figure 5-9. Pore size distribution of 165/TDS leached in granitic groundwater, as
determined by thermoporometry: (a) structure up to 4 nm; (b) structure
beyond 4 nm.

121
indicators of the degree of surface alteration. As before, a decrease in reflected intensity
indicates surface roughening.
Laboratory-leached specimens
Figures 5-10 and 5-11 show the FTIRRS results from deionized water and granitic
groundwater samples. Both specimens show extensive surface alteration and roughening.
The large reflectance band present in the unleached glass has undergone decoupling into
three peaks. The peaks centered at 1125 and 1020 cm 1 appear to be associated with Si-
O-Si and Si-OR bonds, respectively. The origin of the peak at 800 cm 1 is unknown.
In contrast, the spectrum of glass leached in WIPP-A brine, shown in Figure 5-12,
is basically unaltered except for intensity. In this case, the origin of surface roughness
appears to be a powdery salt precipitate covering the surface. The underlying glass shows
only slight leaching effects.
Field-leached specimens
FTIRRS analysis of glass specimens leached for two years in the Stripa and MIIT
studies are shown in Figures 5-13 and 5-14. Both specimens show a limited amount of
corrosion, evidenced by the decoupling of the main reflectance band. Surfaces of these
samples showed only minor roughening and were still shiny in some areas, due to locally
high SA/V values within the restricted space between samples in the burial assembly.
Secondary Ion Mass Spectrometry
Secondary ion mass spectrometry (SIMS) has been heavily utilized as a tool in the
investigation of alteration layers on nuclear waste glasses [Lod85, Lod86, Lod89,

REFLECTANCE
122
WAVENUMBER
Figure 5-10. FT1RR spectrum of 165/TDS before and after leaching in deionized water.

REFLECTANCE
123
WAVENUMBER
Figure 5-11. FTIRR spectrum of 165/TDS before and after leaching in granitic
groundwater (lab study).

REFLECTANCE
124
WAVENUMBER
Figure 5-12. FTIRR spectrum of 165/TDS before and after leaching in WIPP-A brine
(laboratory study).

REFLECTANCE (%)
125
Figure 5-13. FTIRR spectrum of 165/TDS before and after leaching in the Stripa
(granite) burial study.

REFLECTANCE(%)
126
Figure 5-14. FTIRR spectrum of 165/TDS before and after leaching in the MI IT (salt)
burial study.

127
Lod90, Lod91]. This technique is capable of measuring cation concentration as a function
of depth with a very high depth resolution, providing a profile of cation percent vs. depth.
Laboratory-leached specimens
The SIMS profile of the specimen leached in granitic groundwater is shown in
Figure 5-15. This specimen has an alteration layer approximately 3 pm thick consisting
of a thin precipitation layer at the outer 0.25 pm, a plateau region between 0.25 and 2.5
pm where cation percent changes very little, and a thin zone between 2.75 and 3 pm
where concentrations approach bulk glass values.
Group I modifier cations Na, Li and K show strong depletions; group II modifier
cations Ca, Sr and Ba are enriched within the plateau zone, while Mg is slightly depleted
in the plateau but significantly enriched at the outer surface. Among the network formers,
Si maintains a nearly constant level within the plateau region; A1 is slightly enriched, and
B shows a very strong depletion. The intermediates Mn and Fe are both enriched within
the plateau.
This profile is shown in Figure 5-16 as a ternary "composition path” diagram
[Deh74], expressed in terms of network-forming, -modifying and intermediate cations
[Wic88, Sun47]. This diagram presents a simpler view of alteration layer compositional
trends. Beginning at the "bulk" composition and moving toward the surface, the
composition first moves away from the modifier comer of the diagram. This behavior
is indicative of the loss of modifier cations Na and Li. The curve then bends toward the
intermediate corner, indicating the predominance of Fe and Mn within this region of the
layer. The compositional plateau is indicated by the six data points which nearly

CAT IONS
at. per cent
128
100X
10%
IX
.IX
.01X
.001%
Figure 5-15.
SIMS depth profile of 165/TDS leached in the laboratory using granitic
groundwater. Dashed lines mark the composition plateau.

129
Figure 5-16. Composition path diagram of alteration layer formed during leaching of
165/TDS in granitic groundwater. Regions corresponding to the surface
and bulk compositions are indicated.

130
coincide. Finally, the outermost precipitate layer is demonstrated by the sharp deviation
of the last data point from the overall trend.
The SIMS profile of the brine-leached sample is shown in Figure 5-17. The
alteration layer on this sample extends to approximately 0.4 pm depth and is dominated
by the presence of Mg deposited from solution. The group I cations Na and Li are
depleted as in the granitic groundwater sample; however, K shows a concentration
maximum located at 0.2 pm. Group II cations Ba, Sr and Ca are depleted, but Mg is
substantially enriched, due to its presence in the brine. The network-formers Si, B and
A1 are well retained at depths greater than 0.2 pm but show depletions at shallower
depths. The intermediate Fe is depleted at depths less than 0.2 pm, while Mn is strongly
enriched within the outer 0.2 pm. These results suggest that the glass has undergone only
minor corrosion and that the region between the outer surface and 0.2 pm is the result of
precipitation of elements from the brine.
This profile is illustrated as a composition path diagram in Figure 5-18. The
initial movement of the bulk composition away from the modifier corner due to Na and
Li loss is seen in the first three datapoints. Beyond this point, the composition moves
sharply toward the modifier-rich comer of the diagram, due to the overwhelming influx
of Mg. The layer from the sample leached in deionized water peeled away from the
sample during drying and was unavailable for SIMS analysis.
Field-leached specimens
The SIMS profile of 165/TDS leached for two years in the Stripa burial study is
shown in Figure 5-19. This profile shows many of the same trends present in the

CAT IONS
at. per cent
131
0 .1 .2 .3 .4 .5 .6 .7 .0 jjm
DEPTH
Figure 5-17. SIMS profile of 165/TDS leached in the laboratory using WIPP-A brine.

132
bormers
Figure 5-18. Composition path diagram of alteration layer formed during leaching of
165/TDS in WIPP-A brine. Regions corresponding to the surface and bulk
compositions are indicated.

CATION % CATION %
DEPTH |im
DEPTH nm
Figure 5-19. SIMS profile of alteration layer formed of 165/TDS during burial in Stripa.

134
corresponding laboratory-leached specimen. Group I cations Li and Na are depleted.
Unlike the laboratory specimen, this sample shows an enrichment of K within the
alteration layer. Group II cations Ca, Mg and Sr are slightly enriched. The network
former Si has a nearly constant concentration throughout the layer, while B is depleted.
Aluminum levels are slightly depressed at the outer surface. Among the intermediates,
Fe is highly enriched within the layer.
Figure 5-20 shows the Stripa burial SIMS data presented as a composition path
diagram. In spite of minor element-to-element differences between the two samples, the
overall trend is nearly identical to that obtained from the laboratory-leached specimen.
The SIMS profile of the field-leached sample from the MIIT study is shown in
Figure 5-21. Trends in this sample are similar to those of the laboratory-leached brine
sample; however, the layer depth is greater in the field-leached specimen. Na and Li
show their characteristic depletion; Mg is strongly enriched in the surface, and the K peak
is present. There is some speculation |Lod89, Lod90] that the K peak marks the reaction
front between the precipitated material and the original glass surface.
The composition path diagram for this profile is shown in Figure 5-22. This path
shows the same trend toward the modifier-rich corner as was observed in the brine-
leached laboratory sample.
Leaching Kinetics
Glass leaching kinetics were determined by measuring the rate of appearance of
Si, B, Li and Na in solution. Data was examined in terms of leach rates for each

135
Figure 5-20. Composition path diagram of alteration layer formed during leaching of
165/TDS in the Stripa (granite) burial study. Regions corresponding to
surface and bulk compositions are indicated.

CATION % CATION %
100
136
10
1
.1
.01
100
10
1
.1
.01
Figure 5-21.
1 2
DEPTH [im
1 2
DEPTH \im
SIMS profile of alteration layer formed on 165/TDS during burial in salt
at the Waste Isolation Pilot Plant (M1IT study).

137
Formers
Intermediates Modifiers
Figure 5-22. Composition path diagram of alteration layer formed during leachin
165/TDS in salt during burial at the Waste Isolation Pilot Plant. Regions
corresponding to the surface and bulk compositions are indicated.
• CTQ

138
element in mol/nrd and also as log cumulative amount leached in mol/m2 vs. log
leaching time.
Figure 5-23 shows the leach rates of the four elements from glass leached in
deionized water, indicating a decrease in leach rate over time. Plotting this data as logQ
vs. logt yielded the graph shown in Figure 5-24. Fitting the data to equation 2-13
indicated exponents of 0.57, 0.59, 0.55 and 0.49 for Si, Na, Li and B, respectively. These
are very close to the value of 0.5 expected in a diffusion-limited reaction.
Leach rates of 165/TDS in granitic groundwater are shown in Figure 5-25. This
data is extremely noisy due to interfering signals from cations present in the groundwater.
It was not possible to obtain meaningful measurement for sodium in these samples.
However, trends are clearer in the logarithmic plot of Figure 5-26. This data shows
exponents of 0.75, 0.83 and 0.87 for Si, Li and B, respectively, indicating a mechanism
intermediate between a diffusion limited reaction (exponent = 0.5) and a constant leach
rate (exponent = 1.0). Due to their extremely high cation concentrations, brine solutions
were not analyzed.
Summary and Discussion
The complexity of 165/TDS and real-world leachants does not permit evaluation
of corrosion mechanisms to the same extent as was possible in alkali-silicate/water
systems. However, the application of the characterization methodology developed for this
study does make it possible to compare 165/TDS alteration with that observed in simpler
systems.

LEACH RATE (mol/m2 • d)
139
0.006
0.005
0.004
0.003 -
0.002 -
0.001
165/TDS
Deionized
â–¡ Li
+ Na
o B
A Si
+
a
a
+
O ü +
A A A
A *
Op 0OO0OOO
I 2 I 2 â–  I L-L.
AAA¿AA¿AAA
20 40 60 80 100 120
TIME (days)
140 160 180
Figure 5-23. Time dependence of leach rates of Li, Na, B, Si from 165/TDS in
deionized water.

140
Figure 5-24. Cumulative amount of Si, Na, Li and B leached from 165/TDS in
deionized water over the duration of the leaching study. Slopes range
from 0.49 to 0.59.

LEACH RATE (mol/m2 • d)
141
0.0028
0.0024
0.002
0.0016 -
0.0012 -
0.008 -
0.004 -
0
I
+ + B t
O O °
£ L
165rTDS
Granitic Groundwater
â–¡ Si
+ Li
o B
â–¡
□ °
+ + + ♦
o O o 0 ° + °
ii»*- Ln-L-SL
-L
o° °
d o +
i u
J L
20 40 60 80 100 120 140
TIME (days)
160 180
Figure 5-25. Time dependence of Li, Si and B leach rates from 165/TDS in granitic
groundwater.

log Q (mol/m2)
142
log t (days)
Figure 5-26.
Cumulative amounts of Si, Li
groundwater over the duration
0.75 to 0.87.
and B leached from 165/TDS in granitic
of the leaching study. Slopes range from

143
Corrosion of 165/TDS in Deionized Water
The alteration layer formed on 165/TDS in deionized water consisted of 1 pm
nodules which persisted throughout the layer. The extreme outer surface was covered
with a thin, irregular material believed to be crystalline precipitate. Examination at very
small scales showed that the layer was comprised of 4-5 nm diameter spheres, similar to
those found in leached Na20-2Si02, suggesting formation by colloidal precipitation.
Analysis by thermoporometry indicated a high degree of porosity with a bimodal pore
size distribution, similar to that of leached Na202Si02. FTIRRS indicated that the
surface had undergone a radical change in structure. Both network modifying and
forming cations appeared in solution with a tl/2 time dependence, as expected for a
diffusion-limited process.
Microstructural similarities between 165/TDS leached in deionized water and
leached Na202Si02 suggest that alteration of 165/TDS occurs by dissolution and
precipitation of leached glass elements as a result of saturation effects within the HDBL.
In spite of the porosity of this layer it is still capable of functioning as a diffusion barrier,
as evidenced by t1/2 leaching kinetics. Though obviously not a solid state barrier, it may
act as both a solution diffusion barrier and a mechanism for maintaining a nearly
saturated solution in contact with the glass. Grambow |Gra92] has discussed how
solution may become saturated with respect to an activated surface complex and thus
decrease leach rates. Since pore water would have a greater concentration of dissolved
glass components than bulk solution, local saturation may exist within the porous surface.
Leach rates would then be controlled by transfer of material from the saturated pore
solution to the unsaturated bulk leachant.

144
Corrosion of 165/TDS in Granitic Groundwater
Alteration of 165/TDS in granitic groundwater produced a surface layer with
numerous outer surface precipitates and crystals, a nanometer-scale particulate structure,
bimodal pore size distribution and radically altered infrared reflection spectrum. SIMS
analysis of this surface indicated a plateau region in which concentration of all but the
most soluble elements remained constant over depth, suggesting precipitated material.
Element release rates were an order of magnitude lower than in deionized water and
followed approximately a t0 h time dependence.
Microstructure and alteration layer composition indicate that this layer also forms
as a result of precipitation. This reaction is probably aided by complexing of glass
species with those present in the groundwater. These species, in particular silicon, also
contribute to the reduced leach rates which were observed.
Corrosion of 165/TDS in W1PP-A Brine
Based on surface analysis, brine seems to have the least impact on glass of the
three leachants studied. SEM indicates that the outer surface of the glass is covered with
Mg-rich material and crystalline deposits from the brine. FTIRR spectra show that the
glass is unaltered except for an increased surface roughness. SIMS profiling of this glass
shows a 0.2 pm-thick layer at the extreme outer surface which is rich in brine
components. The underlying glass is affected to only a minor degree by alkali depletion
in the region of 0.2 to 0.4 pm.

145
It appears that brine precipitation products form a barrier at the glass surface
which limits leaching. In addition to precipitation effects, it may also be reasoned that
brine is a less agressive leachant. Because brine has an extremely high concentration of
cations, much of the water would be tied up within hydration spheres of the cations, and
thus unavailable for glass attack [Eil74],
Correlation of Laboratory and Field Studies
Comparison of FTIRR spectra of laboratory and field specimens leached in granitic
media indicates that alteration was more extensive in the laboratory-leached specimen.
The spectrum of the laboratory-leached glass was significantly altered and reduced in
intensity. The spectrum of the corresponding burial sample showed only minor changes
in the form of a slight decoupling of the main reflectance band. For samples leached in
salt media, the spectrum of the laboratory specimen has a low intensity, indicating a
rough surface due to the presence of a precipitate, but shows less alteration than the field-
leached sample.
SIMS analysis showed similar elemental trends in the granitic burial and
laboratory specimens. The laboratory-leached sample was affected to a greater depth and
showed a composition plateau which was absent in the field-leached specimen. In spite
of this difference, compositional ternary plots show that the overall composition variation
follows similar trends in both laboratory and field specimens. The field- and laboratory-
leached brine samples also produced comparable surface layers. Both specimens display
the characteristic Mg surface enrichment and K peak as well as a thin reaction zone.

146
Compositor! path diagrams show the same drastic departure toward the modifier-rich
corner of the diagram due to Mg intrusion into the surface of both samples.
This suggests that glass alteration produces similar types of surfaces in both
laboratory and field environments. Although rates of surface layer formation differed in
laboratory- and field-leaching studies, and some elements appeared to behave differently
in the two settings, the overall layer compositions were very similar whether formed in
the laboratory or field. This is displayed most clearly in the composition path diagrams.

CHAPTER 6
CONCLUSIONS AND SUGGESTIONS
FOR FUTURE WORK
Conclusions
This work has demonstrated the value of an integrated research approach in
addressing glass corrosion. Although these glasses have been studied by numerous
workers, most prior studies addressed limited topics, such as composition or kinetics.
Few considered microstructure, and even fewer adequately studied all three.
Three fundamental reaction scenarios were identified in binary glasses. In the
first, the glass reacts by simple ion exchange of alkali ions. This permits preservation of
the original silica network and leads to a dense, coherent silica surface which functions
as a solid-state diffusion barrier. This particular mechanism prevails in glasses where the
alkali release rate is low, and near-neutral pH values are mainatined within the HDBL,
as was the case with Li202Si02.
Binary glasses also may corrode by congruent dissolution, with silica becoming
sufficiently supersaturated within the HDBL to precipitate, forming nanometer-sized
colloids. These colloids form aggregates, approximately 0.1 (im in diameter, which
precipitate onto the glass surface. As this process occurs, a highly porous surface is
produced which is capable of changing the leach rates of glass components. This mode
of corrosion was observed in Na20-2Si02.
147

148
A third corrosion mode involves congruent dissolution of the glass but without
subsequent layer formation. In this case, rapid leaching of the glass results in sufficiently
high pH values within the HDBL that silica precipitation is suppressed. This occurred
in K20-2Si02.
Understanding these primitive processes and the associated microstructures and
leaching kinetics provided a basis for interpreting corresponding data from the nuclear
waste glass studies. Leached nuclear waste glasses demonstrated highly porous alteration
layers with a colloid-like microstructure, suggesting that they form by a dissolution-
precipitation process.
It is worthy to note that the microstructural observations of this study corroborate
and unify the concepts of Grambow’s geochemical model and the Savannah River
leachability model. The Savannah River model’s description of surface layers as diffusion
barriers is reinforced by the observation of diffusion-limited kinetics in the 165/TDS-
deionized water system.
The conclusion that surface layers result from precipitation of colloids within the
HDBL provides considerable validation of Grambow's claim that alteration product
composition is determined by solubility reactions of glass components in solution.
However, the existence of a concentration gradient between the HDBL and bulk solution
indicates that Grambow's model is most applicable to processes occurring within the
HDBL and/or within the pore water of alteration layers, rather than the bulk solution
[Gra86].

149
Future Work
A number of studies may be devised to test aspects of the model described in
Chapter 4. The binary glass study could be extended to cover compositions other than
33 mole percent alkali oxide. Since the alteration mode is determined by HDBL solution
conditions, reducing the alkali content of K20-containing glass should reduce the pH of
the HDBL, thereby changing the corrosion mechanism from congruent dissolution to
colloidal precipitation. Similarly, reducing the Na20 content from 33% in a sodium
silicate glass should result in a preserved corrosion surface as was found in Li2O2Si02.
Similar effects were noted in work by Boksay et al. [Bok68], who observed diffusion-
limited leaching of K from a potassium-silicate glass of unspecified composition. In
addition, Rana and Douglas [RanólaJ observed a fragile, opaque silica residue, similar to
what was observed in corroded Na20-2Si02, after leaching 15K20-85Si02 glass.
The conditions of the HDBL also could be perturbed by external influences such
as vigorous stirring during corrosion |Che87j. This should have the effect of diluting the
HDBL and suppressing any precipitation processes which might otherwise occur.
Neutron scattering studies offer an excellent vehicle for studying small-scale
microstructures such as those found here. SANS data reduction in this study was limited
to more accessible techniques. Considerable potential exists for application of
structural models based on first-principles scattering calculations and their application to
colloid agglomeration models.
Leaching studies of binary glasses in "repository-relevant” leachants such as those
studied here could be used to identify leachant-dependent processes in a simpler system.

150
This also could provide a way to examine the incorporation of solution cations into the
glass alteration product.
Finally, future work with nuclear waste glasses should include use of surface
sampling techniques to provide some indication of solution composition gradients. In
addition, a more intensive study of kinetics would be worthwhile. Calculation of a
diffusion coefficient, based on the Savannah River leachability model, could test the
presumption that pore water is functioning as a diffusion barrier in this material.

REFERENCES
Abr90
Ale54
A1169
A1170
A1171
And50
Bal84
Bla72
Bok68
Bra90
Abrajano, T.A., J.K. Bates, A.B. Woodland, J.P. Bradley and W.L.
Bourcier, "Secondary Phase Formation During Nuclear Waste Glass
Dissolution," Clays and Clay Minerals, 38(5), 537-548 (1990).
Alexander, G.B., W.M. Heston and R.K. Eiler, "The Solubility of
Amorphous Silica in Water," J. Phys. Chem., 58(6), 453-455 (1954).
Allen, L.H. and E. Matijevic, "Stability of Colloidal Silica I. Effect of
Simple Electrolytes," J. Colloid Interface Sci., 31, 287-296 (1969).
Allen, L.H. and E. Matijevic, "Stability of Colloidal Silica II. Ion
Exchange," J. Colloid Interface Sci., 33, 420-429 (1970).
Allen, L.H. and E. Matijevic, "Stability of Colloidal Silica III. Effect of
Hydrolyzable Cations," J. Colloid Interface Sci., 35, 66-76 (1971).
Anderson, S., "Investigation of Structure of Glasses by Their Infrared
Reflection Spectra," J. Am. Ceram. Soc., 33(2), 45-51 (1950).
Bale, H.D. and P.W. Schmidt, "Small-Angle X-Ray Scattering
Investigation of Submicroscopic Porosity with Fractal Properties," Phys.
Rev. Letters, 53(6), 596-599 (1984).
Blachere, J.R. and J.E. Young, "The Freezing Point of Water in Porous
Glass," J. Am. Ceram. Soc., 55(6), 306-308 (1972).
Boksay, Z., G. Bouquet and S. Dobos, "The Kinetics of the Formation of
Leached Layers on Glass Surfaces," Phys. Chem. Glasses, 9(2), 69-71
(1968).
Brandys, M., M. Gong, R.E. Sassoon, A. Barkatt and P.B. Macedo,
"Analysis of Brine Leachates from Materials Interface Interactions Tests:
Leaching of Lithium and Zirconium from Nuclear Waste Glass," Ceramic
Transactions Vol. 9: Nuclear Waste Management III, (G.B. Mellinger,
ed.), The American Ceramic Society, Westerville, OH, 1990, pp. 287-296.
151

152
Bru77
Budól
Bun83
Bun84
Bun88
Cha58
Che87
Che81
Cla76a
Cla83
Cla76b
Brun, M., A. Lallemand, J.F. Quinson and C. Eyraud, "A New Method for
the Simultaneous Determination of the Size and Shape of Pores: The
Thermoporometry," Thermochim. Acta, 21, 59-88 (1977).
Budd, S.M., "The Mechanisms of Chemical Reaction Between Silicate
Glass and Attacking Agents," Phys. Chem. Glasses, 2(4), 111-114 (1961).
Bunker, B.C., G.W. Arnold, E.K. Beauchamp and D.E. Day, "Mechanisms
for Alkali Leaching in Mixed Na-K Silicate Glasses," J. Non-Cryst. Solids,
58, 295-322 (1983).
Bunker, B.C., T.J. Headley and S.C. Douglas, "Gel Structures in Leached
Alkali Silicate Glass," Mat. Res. Soc. Symp. Proc. Vol. 32: Better
Ceramics Through Chemistry, (C.J. Brinker, D.E. Clark and D.R. Ulrich,
eds.), North-Holland, New York, 1984, pp. 41-46.
Bunker, B.C., D.R. Tallant, T.J. Headley, G.L. Turner and R.J. Kirkpatrick,
"The Structure of Leached Sodium Borosilicate Glass," Phys. Chem.
Glasses, 29(3), 106-120 (1988).
Charles, R.J., "Static Fatigue of Glass I," J. Appl. Phys 29, 1549-1553
(1958).
Chen, D.G., "Glass/Water Interface Reactions During the Corrosion of
Flurozirconate Glasses," Masters Thesis, University of Florida, Gainesville,
FL, 1987.
Chen, H. and J.W. Park, "Atmospheric Reaction at the Surface of Sodium
Disilicate Glass," Phys. Chem. Glasses, 22(2), 39-42 (1981).
Clark, D.E., W.A. Aeree and L.L. Hench, "Electron Microprobe Analysis
of Corroded Soda-Lime-Silica Glasses," J. Am. Ceram. Soc., 59(9-10),
463-464 (1976).
Clark, D.E., H. Christensen, H.P. Hermansson, S.B. Sundvall and L.
Werme, "Effects of Flow on Corrosion and Surface Film Formation on an
Alkali Borosilicate Glass," Advances in Ceramics Vol. 8: Nuclear Waste
Management. (G.G. Wicks and W.A. Ross, eds.), The American Ceramic
Society, Westerville, OH, 1983, pp. 19-29.
Clark, D.E., M.R. Dilmore, E.C. Ethridge and L.L. Hench, "Aqueous
Corrosion of Soda-Silica and Soda-Lime-Silica Glass," J. Am. Ceram.
Soc., 59(1-2), 62-65 (1976).

153
Cla77
Cla79
Cla89
Cra86
DeH74
EÍ174
Elm58
E1S72
Esc75
Eth77
Eve88
Clark, D.E., E.C. Ethridge, M.F. Dilmore and L.L. Hench, "Quantitative
Analysis of Corroded Glass Using Infrared Frequency Shifts," Glass Tech.,
18(4), 121-124 (1977).
Clark, D.E., C.G. Pantano, Jr. and L.L. Hench, Corrosion of Glass, Books
for Industry, New York (1979).
Clark, D.E., B.K. Zoitos, G.G. Wicks and K.A. Molen, "Infrared Reflection
Spectroscopy-Part of an Integrated Approach to MIIT Sample Analysis,"
Testing of High-Level Wasteforms Under Repository Conditions, (T.
McMenamin, ed.), EUR 12017 EN, Commission of the European
Communities, Brussels, 1989, pp. 140-151.
Craievich, A., M.A. Aegerter, D.I. dos Santos, T. Woignier and J.
Zarzycki, "A SAXS Study of Silica Aerogels," J. Non-Cryst. Solids, 86,
394-406 (1986).
DeHoff, R.T., K.J. Anusavice and C.C. Wan, "Diffusion Composition Path
Patterns in Ternary Systems," Met. Trans., 5, 1113-1118 (1974).
Eiler, R.K., The Chemistry of Silica, John Wiley and Sons, New York,
1974.
Elmer, T.H., M.E. Nordberg, "Solubility of Silica in Nitric Acid
Solutions," J. Am. Ceram. Soc, 41(12), 517-520 (1958).
El-Shamy, T.M., J. Lewins and R.W. Douglas, "The Dependence on the
pH of the Decomposition of Glasses by Aqueous Solutions," Glass Tech.,
13(3), 81-87 (1972).
Escard, J.H. and D.J. Brion, "Study of Composition of Leached Glass
Surfaces by Photoelectron Spectroscopy," J. Am. Ceram. Soc., 58(7-8),
296-299 (1975).
Ethridge, E.C., "Mechanisms and Kinetics of Binary Alkali Silicate Glass
Corrosion," PhD Dissertation, University of Florida, Gainesville, FL
(1977).
Everett, D.H., Basic Principles of Colloid Science, The Royal Society of
Chemistry, Letchworth, England, 1988.

154
Ewi87
Fil86
Ger87
Gos78
Gra82
Gra92
Gra86
Gra84
Hen90
Ewing, R.C. and M.J. Jercinovic, "Natural Analogues: Their Application
to the Prediction of the Long-Term Behavior of Nuclear Waste Forms,"
Mat. Res. Soc. Symp. Proc. Vol. 84: Scientific Basis for Nuclear Waste
Management X, (J.K. Bates and W.B. Seefeldt, eds.), Materials Research
Society, Pittsburgh, PA, 1987, pp. 67-83.
Fillet, S., J. Phalippou, J. Zarzycki and J.L. Nogues, "Texture of Gels
Produced by Corrosion of Radiactive Waste Disposal Glass," J. Non-Cryst.
Solids, 82, 232-238 (1986).
Gervais, F., A.B.D. Massiot, J.P. Coutures, M.H. Chopinet and F. Naudin,
"Infrared Reflectivity Spectroscopy of Silicate Glasses," J. Non-Cryst.
Solids, 89, 384-401 (1987).
Gossink, R.G., H.A.M. deGrefte and H.W. Werner, "SIMS Analysis of
Aqueous Corrosion Profiles in Soda-Lime-Silica Glass," J. Am. Ceram.
Soc., 62(1), 4-9 (1978).
Grambow, B., "The Role of Metal Ion Solubility in Leaching of Nuclear
Waste Glasses," Mat. Res. Soc. Symp. Proc. Vol. 11: Scientific Basis for
Nuclear Waste Management V. (W. Lutze, ed.), North Holland, New York,
NY, 1982, pp. 93-102.
Grambow, B., "Geochemical Approach to Glass Dissolution," in Corrosion
of Glass, Ceramics and Ceramic Superconductors, (D.E. Clark and B.K.
Zoitos, eds.), Noyes, Park Ridge, NJ, 1992, pp. 124-152.
Grambow, B., H.P. Hermansson, I.K. Bjorner, H. Christensen and L.
Werme, "Reaction of Nuclear Waste Glass with Slowly Flowing Solution,"
Advances in Ceramics Vol. 20: Nuclear Waste Management II, (D.E.
Clark, W.B. White and A.J. Machiels, eds.), The American Ceramic
Society, Westerville, OH, 1986, pp. 465-474.
Grambow, B. and D.M. Strachan, "Leach Testing of Waste Glasses Under
Near-Saturation Conditions," Mat. Res. Soc. Symp. Proc. Vol. 26:
Scientific Basis for Nuclear Waste Management VII, (G.L. McVay, ed.),
North Holland, New York, NY, 1984, pp. 623-634.
Hench, L.L. and J.K. West, "The Sol-Gel Process," Chem. Rev., 90, 33-73
(1990).

155
Hus90
Jan86
Jan92
Jer89
Kin76
Kit60
Kra56
Lau86
Lee86
Lenl7
Lod91
Husung, R.D. and R.H. Doremus, "The Infrared Transmission Spectra of
Four Silicate Glasses Before and After Exposure to Water," J. Mater. Res.,
5(10), 2209-2217 (1990).
Jantzen, C.M., "Prediction of Nuclear Waste Glass Durability from Natural
Analogs," Advances in Ceramics Vol. 20: Nuclear Waste Management II,
(D.E. Clark, W.B. White and A.J. Machiels, eds.), The American Ceramic
Society, Westerville, OH, 1986, pp. 703-712.
Jantzen, C.M., "Thermodynamic Approach to Glass Corrosion," in
Corrosion of Glass, Ceramics and Ceramic Superconductors, (D.E. Clark
and B.K. Zoitos, eds.), Noyes, Park Ridge, NJ, 1992, pp. 153-217.
Jercinovic, M.S., S. Kaser and R.C. Ewing, "Observations of Surface
Layers Formed on Basaltic and Borosilicate Glass: 6 Months and 1 Year
MIIT Experiments," Testinsz of High Level Wasteforms Under Repository
Conditions, (T. McMenamin, ed.), EUR 12017 EN, Commission of the
European Communities, Brussels, 1989, pp. 183-191.
Kingery, W.D., H.K. Bowen and D.R. Uhlman, Introduction to Ceramics,
John Wiley & Sons, New York, NY, 1976.
Kitahara, S. "The Polymerization of Silicic Acid Obtained by the
Hydrothermal Treatment of Quartz and the Solubility of Amorphous
Silica," Rev. Phys. Chem. Japan, 30(2), 131-137 (1960).
Krauskopf, K.B., "Dissolution and Precipitation of Silica at Low
Temperatures," Geochim. Cosmochim. Acta, 10(1), 1-26 (1956).
Laudise, R.A. and D.W. Johnson, Jr., "Supercritical Drying of Gels," J.
Non-Cryst. Solids, 79, 155-164 (1986).
Lee, C.T., "Surface and Solution Chemistry of Glass/Water Interactions,"
PhD Dissertation, University of Florida, Gainesville, FL (1986).
Lenher, V. and H.B. Merrill, "Solubility of Silica," J. Am. Chem. Soc., 39,
2630-2640 (1917).
Lodding, A.R., D.E. Clark, E.U. Engstrom, H. Odelius, M. Schuhmacher,
G.G. Wicks and B.K. Zoitos, "SIMS Applications on Nuclear
Wasteforms," Ceramics Today-Tomorrow's Ceramics, (P. Vincenzini, ed.),
Elsevier, New York, 1991, pp. 3121-3129.

156
Lod86
Lod90
Lod89
Lod85
Mac82
Mae91
Mat83
Men84
Mol89
Lodding, A.R., E.U. Engstrom, D.E. Clark, L.O. Wertne and G.G. Wicks,
"SIMS Analysis of Leached Layers Formed on SRL Glasses During
Burial," Advances in Ceramics, Vol. 20: Nuclear Waste Management II,
(D.E. Clark, W.B. White and A.J. Machiels, eds.), The American Ceramic
Society, Westerville, OH, 1986, pp. 567-581.
Lodding, A.R., E.U. Engstrom, D.E. Clark and G.G. Wicks, "Quantitative
Concentration Profiling and Element Balance in SRL Glass After Two
Years in W1PP," Ceramic Transactions Vol. 9: Nuclear Waste
Management III, (G.B. Mellinger, ed.), The American Ceramic Society,
Westerville, OH, 1990, pp. 317-334.
Lodding, A.R., E.U. Engstrom and H. Odelius, "Elemental Profiling by
SIMS of Leached Layers in Repository Tested SRL Waste Glass," Testing
of High Level Wasteforms Under Repository Conditions, (T. McMenamin,
ed.), EUR 12017 EN, Commission of European Communities, Brussels,
1989, pp. 127-139.
Lodding, A.R., H. Odelius, D.E. Clark and L.O. Werme, "Element
Profding by Secondary Ion Mass Spectrometry of Surface Layers in
Glass," Mikrochimica Acta, 11, 145-161 (1985).
Macedo, P.B., A. Barkatt and J.H. Simmons, "A Flow Model for the
Kinetics of Dissolution of Nuclear Waste Glasses," Nuc. Chem. Waste
Management, 3, 13-21 (1982).
Maekawa, H., T. Maekawa, K. Kawamura and T. Yokokawa, "The
Structural Groups of Alkali Silicate Glasses Determined from ‘'Si MAS-
NMR," J. Non-Cryst. Solids, 127(1), 53-64 (1991).
Materials Characterization Center, "MCC-1P Static Leach Test Method,"
in Nuclear Waste Materials Handbook, DOE/TIC-11400: Test Methods
1983.
Mendel, J.E., "Final Report of the Defense High-Level Waste Leaching
Mechanisms Program," PNL-5157/UC-70, Pacific Northwest Laboratory
(1984).
Molecke, M.A., "Technical Operations and Data Collection Details of the
In Situ WIPP Materials Interface Interactions Test," Testing of High Level
Wasteforms Under Repository Conditions, (T. McMenamin, ed.), EUR
12017 EN, Commission of the European Communities, Brussels, 1989, pp.
67-77.

157
Mol86
Mor64
Oko57
Pau77
Pau82
Plo84
Rou89
Qui88
Qui85
Qui86
Ram90
Molecke, M.A. and G.G. Wicks, "Test Plan: W1PP Materials Interface
Interactions Test (MIIT)," Sandia National Laboratories (1986).
Morey, G.W., R.O. Fournier and J.J. Rowe, "The Solubility of Amorphous
Silica at 25°C," J. Geophys. Res., 69(10), 1995-2002 (1964).
Okomoto, G., T. Okura and K. Goto, "Properties of Silica in Water,"
Geochim. Cosmochim. Acta, 12, 123-132 (1957).
Paul, A., "Chemical Durability of Glasses: A Thermodynamic Approach,"
J. Mat. Sci 12(4), 2246-2268 (1977).
Paul, A., Chemistry of Glasses, Chapman and Hall, New York, 1982.
Plodinec, M.J., C.M. Jantzen and G.G. Wicks, "Thermodynamic Approach
to Prediction of the Stability of Proposed Radwaste Glasses," Advances in
Ceramics, Vol. 8, Nuclear Waste Management, (G.G. Wicks and W.A.
Ross, eds.), The American Ceramic Soc., Inc., Columbus, OH, 1984, pp.
826-832.
Rousset, J.L., A. Boukenter, B. Champagnon, E. Duval, J.F. Quinson, M.
Chatelut, J. Dumas and J. Serughetti, "Textural and Structural Studies of
Aerogels by Raman Scattering and Thermoporometry," Revue de Physique,
C4(4), 163-166 (1989).
Quinson, J.F. and M. Brun, "Progress in Thermoporometry,"
Characterization of Porous Solids, (K.K. Unger, ed.), Elsevier, Amsterdam,
1988, pp. 307-315.
Quinson, J.F., J. Dumas and J. Serughetti, "Wet Silica Gels: Textural
Characterization," Journal de Physique, C8( 12), 476-471 (1985).
Quinson, J.F., J. Dumas and J. Serughetti, "Alkoxide Silica Gel: Porous
Structure by Thermoporometry," J. Non-Cryst. Solids, 79, 397-404 (1986).
Ramsey, W.G. and G.G. Wicks, "WIPP/SRL In Situ Tests: Laboratory
Support Experiments," Ceramic Transactions Vol. 9: Nuclear Waste
Management III. (G.B. Mellinger, ed.), The American Ceramic Society,
Westerville, OH, 1990, pp. 335-346.

158
Ranóla
Ranólb
Ran87
Ric84
Rim80
Sal84
San73
San74
Sas90
Sch89a
Sch87
Sch89b
Rana, M.A. and R.W. Douglas, "The Reaction Between Glass and Water.
Part 1. Experimental Methods and Observations," Phys. Chem. Glasses,
2(6), 179-195 (1961).
Rana, M.A. and R.W. Douglas, "The Reaction Between Glass and Water.
Part 2. Discussion of the Results," Phys. Chem. Glasses, 2(6), 196-205
(1961).
Randall, M.S. "Phase Instabilities of Mixed Cadmium-Lead-Fluoride Ionic
Glasses," Masters Thesis, University of Florida, Gainesville, FL (1987).
Richter, T., G.H. Frischat, B. Borchardt, S. Scherrer and S. Weber, "SIMS
Analysis of a Leached Soda-Lime Glass," Revista della Staz. Sper. Vetro,
5, 105-109 (1984).
Rimstidt, J.D. and H.L. Barnes, "The Kinetics of Silica-Water Reactions,"
Geochim. Cosmochim. Acta, 44(11), 1683-1699 (1980).
Sales, B.C., C.W. White, G.M. Begun and L.A. Boatner, "Surface Layer
Formation on Corroded Nuclear Waste Glass," J. Non-Cryst. Solids, 67,
245-264 (1984).
Sanders, D.M., "Structure and Kinetics of Glass Corrosion," PhD
Dissertation, University of Florida, Gainesville, FL ((1973).
Sanders, D.M., W.B. Person and L.L. Hench, "Quantitative Analysis of
Glass Structure with the Use of Infrared Reflection Spectra," Appl. Spec.,
28(3), 247-255 (1974).
Sasoon, R.E., M. Gong, M. Brandys, M. Adel-Hadadi, A. Barkatt and P.B.
Macedo, "Analysis of Brine Leachates from Materials Interface
Interactions Tests: Leaching of Nuclear Waste Glass Doped with
Chemical Tracers," Ceramic Transactions Vol. 9: Nuclear Waste
Management III. (G.B. Mellinger, ed.), The American Ceramic Society,
Westerville, OH, 1990, pp. 307-316.
Schaefer, D.W., "Polymers, Fractals, and Ceramic Materials," Science, 243,
1023-1027 (1989).
Schaefer, D.W., B.C. Bunker and J.P. Wilcoxon, "Are Leached Porous
Glasses Fractal?," Phys. Rev. Letters, 58(3), 284 (1987).
Schaefer, D.W., B.C. Bunker and J.P. Wilcoxon, "Fractals and Phase
Separation," Proc. R. Soc. London, A, 423(1864), 35-53 (1989).

159
Sch86
Sch90
Sch89c
Sme85
Sop83
Spr90
Sun47
Swe69
Tac90
Tom83
Vea8()
Schaefer, D.W., K.D. Keefer, "Structure of Random Porous Materials:
Silica Aerogel," Phys. Rev. Letters 56(20), 2199-2202 (1986).
Scherer, G.W., "Theory of Drying," J. Am. Ceram. Soc., 73(1), 3-14
(1990).
Schmidt, P.W., A. Hohr, H.B. Neumann, H. Kaiser, D. Avnir and J.S. Lin,
"Small Angle X-Ray Scattering Study of the Fractal Morphology of Porous
Silicas," J. Phys. Chem., 90(9), 5016-5023 (1989).
Smets, B.M.J. and M.G.W. Tholen, "The pH Dependence of the Aqueous
Corrosion of Glass," Phys. Chem Glasses, 26(3), 60-63 (1985).
Soper, P.D., D.D. Walker, M.J. Plodinec, G.J. Roberts and L.F. Lightner,
"Optimization of Glass Composition for the Vitrification of Nuclear Waste
at the Savannah River Plant," Bull. Am. Ceram. Soc., 26, 1013-1018,
(1983).
Sprenger, D., H. Bach, W. Meisel and P. Gutlich, "XPS Study of Leached
Glass Surfaces," J. Non-Cryst. Solids, 126, 111-129 (1990).
Sun, K.H., "Fundamental Conditions of Glass Formation," J. Am. Ceram.
Soc., 30, 277-281 (1947).
Sweet, J.R. and W.B. White, "Study of Sodium Silicate Glasses and
Liquids by Infrared Reflection Spectroscopy," Phys. Chem. Glasses, 10(6),
246-251 (1969).
Tacca, J.A. and G.G. Wicks, "WIPP/SRL In Situ Tests: MIIT Program-
Surface Studies of SRL Waste Glasses," Ceramic Transactions Vol. 9:
Nuclear Waste Management III, (G.B. Mellinger, ed.), The American
Ceramic Society, Inc., Westerville, OH, 1990, pp. 271-286.
Tomozawa, M. and S. Capella, "Microstructure in Hydrated Silicate
Glasses," Comm. Am. Ceram. Soc., C-24,25 February (1983).
Veal, B.W., D.J. Lam, A.P. Paulikas and D.P. Karim, "X-Ray
Photoelectron Spectroscopy Studies of Silicate Glasses: Implications to
Bonding and Leaching," Nucl. Tech., 51, 136-142 (1980).

160
Ver89 Vemaz, E. and N. Godon, "Examination of Ultrathin Cross-sections from
R7T7 Glass Samples after 6 Months and 1 Year Alteration in the WIPP,"
Testing of High Level Wasteforms Under Repository Conditions, (T.
McMenamin, ed.), EUR 12017 EN, Commission of the European
Communities, Brussels, 1989, pp. 81-90.
Wal77 Walker, M.M., "An Investigation into the Bonding Mechanisms of
Bioglass," Masters Thesis, University of Florida, Gainesville, FL (1977).
Wal83 Wallace, R.M. and G.G. Wicks, "Leaching Chemistry of Defense
Borosilicate Glass," Mat. Res. Soc. Synip. Proc. Vol. 15: Scientific Basis
for Nuclear Waste Management VI, (D.G. Brookins, ed.), North-Holland,
New York, 1983, pp. 23-28.
Wan58 Wang, F.F. and F.V. Tooley, "Influence of Reaction Products on Reaction
Between Water and Soda-Lime-Silica Glass,” J. Am. Ceram. Soc., 41(12),
521-524 (1958).
War86 Wamock, J., D.D. Awscholom and M.W. Schafer, "Geometrical
Supercooling of Liquids in Porous Glasses," Phys. Rev. Letters, 57(14),
1753-1756 (1986).
Wat7() Watillon, A., "The Stability of Amorphous Colloidal Silica,” J. Colloid
Interface Sci., 33, 430-438 (1970).
Whi56 White, D.E., W.W. Brannock and K.J. Murata, "Silica in Hot Spring
Waters," Geochim. Cosmochim. Acta, 10(1), 27-59 (1956).
Wic85a Wicks, G.G., "Nuclear Waste Glasses," in Treatise on Materials Science
and Technology Vol. 26—Glass IV. (M. Tomozawa and R.H. Doremus,
eds.) Academic Press, New York, NY, 1985, pp. 57-118.
Wic85b Wicks, G.G., "WIPP/SRL In Situ Tests and Laboratory Testing Program-
Part I: MI1T Overview, Nonradioactive Glass Studies, E.I. du Pont de
Nemours and Company, Savannah River Laboratory, DP-1706, 1985.
Wic87 Wicks, G.G., "WIPP/SRL In Situ Tests-Part II: Pictorial History of MIIT
and Final MIIT Matrices, Assemblies and Sample Listing," E.I. du Pont de
Nemours and Company, Savannah River Laboratory, DP-1733, 1987.
Wic88 Wicks, G.G., "WIPP/SRL In Situ Tests—Part III: Compositional
Correlations of MIIT Waste Glasses," E.I. du Pont de Nemours and
Company, Savannah River Laboratory, DP-1769, August, 1988.

161
Wic92
Wic86
Wic89
Zhu86a
Zhu86b
Zoi89
Wicks, G.G., "Nuclear Waste Glasses: Corrosion Behavior and Field
Tests," in Corrosion of Glass, Ceramics and Ceramic Superconductors,
(D.E. Clark and B.K. Zoitos, eds.), Noyes, Park Ridge, NJ, 1992, pp. 218-
268.
Wicks, G.G. and M.A. Molecke, "WIPP/SRL In Situ Testing Program,"
Advances in Ceramics. Vol. 20: Nuclear Waste Management II. (D.E.
Clark, W.B. White and A.J. Machiels, eds.), The American Ceramic
Society, Westerville, OH, 1986, pp. 657-667.
Wicks, G.G., W.G. Ramsey and K.A. Molen, "Correlation of MIIT Glass
and Waste Glass Compositions," Testing of High Level Wasteforms Under
Repository Conditions. (T. McMenamin, ed.), EUR 12017 EN,
Commission of the European Communities, Brussels, 1989, pp. 158-171.
Zhu, B.F., "Nuclear Waste Glass Leaching in a Simulated Granite
Repository," PhD Dissertation, University of Florida, Gainesville, FL
(1986).
Zhu, B.F., D.E. Clark, A.R. Lodding and G.G. Wicks, "Two-Year
Leaching Behavior of Three SRL Nuclear Waste Glasses in Granite,"
Advances in Ceramics, Vol. 20: Nuclear Waste Management II, (D.E.
Clark, W.B. White and A.J. Machiels, eds.), The American Ceramic
Society, Westerville, OH, 1989, pp. 591-599.
Zoitos, B.K., D.E. Clark, A.R. Lodding and G.G. Wicks, "Correlation of
Laboratory and Stripa Field Leaching Studies," Mat. Res. Soc. Svmp. Proc.
Vol. 127: Scientific Basis for Nuclear Waste Management, (W. Lutze and
R.C. Ewing, eds.), The Materials Research Society, Pittsburgh, PA, 1989,
pp. 145-151.

BIOGRAPHICAL SKETCH
Bruce K. Zoitos was bom August 3, I960 in Indianapolis, Indiana. He received
his Bachelor of Science degree in physics from Purdue University in 1982 and spent the
following year employed as a health physics technician at Oak Ridge Associated
Universities in Oak Ridge, Tennessee. He entered the University of Florida as a graduate
student in January 1984. He has been employed as a laboratory scientist at Gates Energy
Products in Gainesville, Florida since April 1991. His interests include insect collecting,
birdwatching and carnivorous plants.
162

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quality as a dissertation for the degree of Doctor of Philosophy.
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and Engineering
I certify that I have read this study and that in my opinion it conforms to
acceptable standards of scholarly presentation and is fully adequate, in scope and
quality, as a dissertation for the degree of Doctor of Philosophy.
(f'r^CL
4,
/¿MAf
Stanley R. Bates
Associate Engineer of Materials
Science and Engineering
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acceptable standards of scholarly presentation and is fully adequate, in scope and
quality, as a dissertation for the degree of Doctor of Philosophy.
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Professor of Environmental
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quality, as a dissertation for the degree of Doctor of Philosophy.
-0.
e.iH.
Robert T. DeHoff/
Professor of Materials Science
and Engineering
I certify that I have read this study and that in my opinion it conforms to
acceptable standards of scholarly presentation and is fully adequate, in scope and
quality, as a dissertation for the degree of Doctor of Philosophy.
(±
Ü.
Alexander R. Lodding
Professor of Physics, Chalmers
University of Technology,
Gothenberg. Sweden
I certify that 1 have read this study and that in my opinion it conforms to
acceptable standards of scholarly presentation and is fully adequate, in scope and
quality, as a dissertation for the degree of Doctor of Philosophy.
E. Dow
Professor of Materials
and Engineering

This dissertation was submitted to the Graduate Faculty of the College of
Engineering and to the Graduate School and was accepted as partial fulfillment of the
requirements for the degree of Doctor of Philosophy.
May, 1992
'Xk~ Winfred M. Phillips
Dean, College of Engineering
Madelyn M. Lockhart
Dean. Graduate School

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