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Optical Diagnostic Techniques in Tribological Analysis

Permanent Link: http://ufdc.ufl.edu/UFE0024739/00001

Material Information

Title: Optical Diagnostic Techniques in Tribological Analysis Applications to Wear Film Characterization, Solid Lubricant Chemical Transition, and Electrical Sliding Contacts
Physical Description: 1 online resource (155 p.)
Language: english
Creator: Windom, Bret
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: aes, disulphide, molybdenum, mos2, polymer, ptfe, raman, spark, spectroscopy, tribology, wear
Mechanical and Aerospace Engineering -- Dissertations, Academic -- UF
Genre: Mechanical Engineering thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Friction and wear have undisputedly huge macroscopic effects on the cost and lifetime of many mechanical systems. The cost to replace parts and the cost to overcome the energy losses associated with friction, although small in nature, can be enormous over long operating times. The understanding of wear and friction begins with the understanding of the physics and chemistry between the reacting surfaces on a microscopic level. Light as a diagnostic tool is a good candidate to perform the very sensitive microscopic measurements needed to help understand the fundamental science occurring in friction/wear systems. Light?s small length scales provide the capabilities to characterize very local surface phenomena, including thin transfer films and surface chemical transitions. Light-based diagnostic techniques provide nearly instantaneous results, enabling one to make in situ/real time measurements which could be used to track wear events and associated chemical kinetics. In the present study, two optical diagnostic techniques were investigated for the analysis of tribological systems. The first technique employed was Raman spectroscopy. Raman spectroscopy was investigated as a possible means for in situ measurement of thin transfer films in order to track the wear kinetics and structural transitions of bulk polymers. A micro-Raman system was designed, built, and characterized to track fresh wear films created from a pin-on-disk tribometer. The system proved capable of characterizing and tracking wear film thicknesses of ~2 ?m and greater. In addition, the system provided results indicating structural changes in the wear film as compared to the bulk when sliding speeds were increased. The spectral changes due to the altering of molecular vibrations can be attributed to the increase in temperature during high sliding speeds. Raman spectroscopy was also used to characterize the oxidation of molybdenum disulphide, a solid lubricant used in many applications, including high vacuum sliding. Resonance Raman effects were observed when an excitation wavelength of 632.8 nm was used. Raman spectroscopy was carried out on amorphous MoS2 while its temperature was increased to track the thermally induced oxidation of the MoS2 surface. In addition, other forms of MoS2not were investigated through Raman spectroscopy in which key distinctions between spectra were made. The second technique employed was atomic emission spectroscopy (AES) used to measure constituent species present in arcs created during electrical sliding contacts. Spectra indicated the presence of copper and zinc in the arcs created between copper fiber bundled brushes and a copper rotor. Atomic emission was used to measure the arc duration with a photo-multiplier tube (PMT) while the collected spectra were processed to assess arc temperature. The results suggest arcing in high-current electrical sliding contacts may be at least partially responsible for the high asymmetrical wear measured during tribology tests.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Bret Windom.
Thesis: Thesis (Ph.D.)--University of Florida, 2009.
Local: Adviser: Hahn, David W.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0024739:00001

Permanent Link: http://ufdc.ufl.edu/UFE0024739/00001

Material Information

Title: Optical Diagnostic Techniques in Tribological Analysis Applications to Wear Film Characterization, Solid Lubricant Chemical Transition, and Electrical Sliding Contacts
Physical Description: 1 online resource (155 p.)
Language: english
Creator: Windom, Bret
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: aes, disulphide, molybdenum, mos2, polymer, ptfe, raman, spark, spectroscopy, tribology, wear
Mechanical and Aerospace Engineering -- Dissertations, Academic -- UF
Genre: Mechanical Engineering thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Friction and wear have undisputedly huge macroscopic effects on the cost and lifetime of many mechanical systems. The cost to replace parts and the cost to overcome the energy losses associated with friction, although small in nature, can be enormous over long operating times. The understanding of wear and friction begins with the understanding of the physics and chemistry between the reacting surfaces on a microscopic level. Light as a diagnostic tool is a good candidate to perform the very sensitive microscopic measurements needed to help understand the fundamental science occurring in friction/wear systems. Light?s small length scales provide the capabilities to characterize very local surface phenomena, including thin transfer films and surface chemical transitions. Light-based diagnostic techniques provide nearly instantaneous results, enabling one to make in situ/real time measurements which could be used to track wear events and associated chemical kinetics. In the present study, two optical diagnostic techniques were investigated for the analysis of tribological systems. The first technique employed was Raman spectroscopy. Raman spectroscopy was investigated as a possible means for in situ measurement of thin transfer films in order to track the wear kinetics and structural transitions of bulk polymers. A micro-Raman system was designed, built, and characterized to track fresh wear films created from a pin-on-disk tribometer. The system proved capable of characterizing and tracking wear film thicknesses of ~2 ?m and greater. In addition, the system provided results indicating structural changes in the wear film as compared to the bulk when sliding speeds were increased. The spectral changes due to the altering of molecular vibrations can be attributed to the increase in temperature during high sliding speeds. Raman spectroscopy was also used to characterize the oxidation of molybdenum disulphide, a solid lubricant used in many applications, including high vacuum sliding. Resonance Raman effects were observed when an excitation wavelength of 632.8 nm was used. Raman spectroscopy was carried out on amorphous MoS2 while its temperature was increased to track the thermally induced oxidation of the MoS2 surface. In addition, other forms of MoS2not were investigated through Raman spectroscopy in which key distinctions between spectra were made. The second technique employed was atomic emission spectroscopy (AES) used to measure constituent species present in arcs created during electrical sliding contacts. Spectra indicated the presence of copper and zinc in the arcs created between copper fiber bundled brushes and a copper rotor. Atomic emission was used to measure the arc duration with a photo-multiplier tube (PMT) while the collected spectra were processed to assess arc temperature. The results suggest arcing in high-current electrical sliding contacts may be at least partially responsible for the high asymmetrical wear measured during tribology tests.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Bret Windom.
Thesis: Thesis (Ph.D.)--University of Florida, 2009.
Local: Adviser: Hahn, David W.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0024739:00001


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PAGE 4

In Situ In Situ IN SITU

PAGE 5

In Situ

PAGE 12

in situ in situ

PAGE 14

Overview in situ

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in situ Analytical Tribology

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in situ In Situ Raman Tribometer In Situ Raman Studies

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in situ in situ in situ in s itu

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In situ in situ in situ PTFE Raman Studies in situ

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MoS2 Raman Study Introduction

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in situ

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Raman Spectroscopy of MoS2 in situ gE gE gE

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zd xy d gE gE

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in situ in situ

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Stacy & Hodul ( Stacy 1995 ) Chen & Wang ( Chen 1974 ) Frequency (cm -1 ) Order Origin Frequency (cm -1 ) Order Origin 34 First 32 First 177 Second 188 Second 287 First 286 First 383 First 383 First 409 First 408.3 First 466 Second 450.2 Second 529 Second 567.3 Second 572 Second 596 Second 601 Second 750 Second 643 Second 778 Second 780 Second 816.7 Second 820 Second Spark Diagnostic Study Introduction gAMLAM gE gE gE LAM gEMLAM gA gE gEMLAM gAMLAM ggAMEM ggAorAM gAMLAM gE gE gE LAM gA gE gEM gA

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Spark Creation Fundamentals

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v E d

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cH R F ccVIR ccTTVxK

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di/dt di VL dt

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CAdI ULRIUt dt CAAbUUUU Rt It RRL Ab a CACLIUU t UUU

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Spark Induced Wear Mechanisms

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Non -Sparking Electric Induced Wear Mechanisms Previous Work

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eI Ie

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Raman Light Scattering

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E mEEt mE mPEEt

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err r re v emvrrrt rm mvrt r m mm vPEt Er tt r v v

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m mmv m mvE PEtr t r E rt r r

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v

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Raman spectroscopy: v v v A v v v B

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ovibvv ov vibv v vibv vibv ov ov

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vibv

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Emission Spectroscopy

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0 1000 2000 3000 4000 5000 6000 7000 250260270280290300Intensity (a.u.)Wavelength (nm) Mg (II) 279.55 Mg(II) 280.27 Mg(I) 285.21 Si(I) 288.158 Fe(II) Fe(II)

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Boltzmann plot: hcE kTNAg Ie u Ihc Econst AgkT hc kT T

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15 16 17 18 19 20 21 22 3 1063.5 1064 1064.5 1065 1065.5 1066 1066.5 106Cu (I) Boltzmann Plot y = 26.355 1.7747e-06x R= 0.99151 ln(lamda*I/gA)Energy Level (m-1)

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IN SITU Tribo -Raman Setup in situ Tribometer

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Laser Excitation

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Raman Collection

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0 2 1044 1046 1048 1041 105300400500600700Intensity (a.u.)Wavenumber (cm-1) Si 520 cm-1 Ar-ion Laser Residual Frequency 501.7 nm Ar-ion Laser Residual Frequency 496.5 nmNo Filter Filter Micro-Raman Si Spectrum

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Results Micro -Raman System Characterization

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0 5000 1 1041.5 1042 1042.5 1043 1041200125013001350140014501500Intensity (a.u.)Raman Shift (cm-1) Custom Micro-Raman Commercial Micro-Raman (Shifted)

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500 1000 1500 2000 2500 1000110012001300140015001600Intensity (a.u.)Raman Shift (cm-1)C-C CH21174 cm-11067 cm-1C-C 1132 cm-1CH2CH2CH2CH21374 cm-11421 cm-11465 cm-11299 cm-1 CH21445 cm-1Custom Micro-Raman 2000 2500 3000 3500 4000 4500 5000 1000110012001300140015001600Intensity (a.u.)Raman Shift (cm-1)Commercial Micro-Raman

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1000 2000 3000 4000 5000 6000 7000 200400600800 100012001400Intensity (a.u.)Raman Shift (cm-1) 632.8 nm Micro-Raman Shifted 1000 Counts Custom Micro-Raman

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0 1000 2000 3000 4000 5000 250300350400450500550600Intensity (a.u.)Raman Shift (cm-1) Residual Ar-ion Laser Line Located @ 496.5 nm 0 1000 2000 3000 4000 5000 6000 560600640680720760800840Intensity (a.u.)Raman Shift (cm-1) 0 500 1000 1500 2000 2500 3000 3500 4000 115012001250 1300 135014001450Intensity (a.u.)Raman Shift (cm-1)

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1400 1500 1600 1700 1800 1900 2000 2100 2200 710715720725730735740745750 79 mins 2883 mns 8334 minsIntensity (a.u.)Raman Shift (cm-1)

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-0.4 -0.2 0 0.2 0.4 0.6 0.8 1 1.2 0 20004000 6000 8000 10000PTFE Raman Signal vs Sliding TimeP/BTime (min)

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-2 -1 0 1 2 3 4 5 2000 4000 60008000 1 104PTFE Wear Track ProfileHeight ( m)X-dir ( m) -2 0 2 4 6 8 10 0 200400600800 1000Zoomed PTFE Wear Track ProfileHeight ( m)X-Dir ( m)

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A B C

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8000 9000 1 1041.1 1041.2 104710715720725730735740745750 Image A Image B Image CIntensity (a.u.)Raman Shift (cm-1)

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500 600 700 800 900 1000 1100 1200 710720730740750 210 min 5875 min 14407 minIntensity (a.u.)Raman Shift (cm-1)

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Polymer Plasticization Results 1 1.5 2 2.5 3 3.5 4 4.5 0 5000 1 1041.5 104P/BTime (min)

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7000 7500 8000 8500 9000 9500 1 1041.05 104704712720728736744752760Intensity (a.u.)Raman Shift (cm-1) Bulk PTFE Slow Wear Track Fast Wear Track PTFE Ribbon (Fast Sliding)

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80 160 240 320 400 480 300320340360380Intensity (a.u.)Raman Shift (cm-1) Unworn 270 min 1320 min 18750 min

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0 500 1000 1500 2000 720725730735740745750Intensity (a.u.)Raman Shift (cm-1) Unworn 270 min 1320 min 18750 min 200 300 400 500 600 700 800 900 1375 1380 1385 1390Intensity (a.u.)Wavenumber (cm-1) Unworn 30 min 7095 min 18750 min 23040 min

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100 150 200 250 300 350 400 280285290295300305Intensity (a.u.)Raman Shift (cm-1) Unworn 30 min 90 min 2970 min 4050 min

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100 200 300 400 500 600 370375380385390395Intensity (a.u.)Wavenumber (cm-1) Unworn 30 min 1140 min 2910 min 200 300 400 500 600 700 800 900 137013751380138513901395Intensity (a.u.)Wavenumber Unworn 30 min 90 min 1290 min 4335 min

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520560600640680 Raman Shift (cm-1) Unworn 90 min 1140 min 2970 min 4050 min 4335 min

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3600 3800 4000 4200 4400 4600 4800 250 300 350 400 450Intensity (a.u.)Raman Shift (cm-1) Room Temperature Heated Sample CF2 twist CF2 scissors 4000 4500 5000 5500 6000 6500 7000 7500 8000 700710720730740750760770Intensity (a.u.)Raman Shift (cm-1) Room Temperature Heated Sample

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4000 4100 4200 4300 4400 4500 500550600650700750800850900Intensity (a.u.)Raman Shift (cm-1) Room Temperature Heated Sample CF2 wag CF2 rock 4000 4500 5000 5500 1150120012501300135014001450Intensity (a.u.)Raman Shift (cm-1) Room Temperature Heated sample CF2 asymmetric stretch C-C stretch C-C symmetric stretch

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Discussion in situ

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in situ

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Fundamental MoS2 Raman Study Raman System

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Results

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0 1000 2000 3000 4000 200400600800 1000Intensity (a.u.)Raman Shift (cm-1) 0.6 mW 6.3 mW380 407 451 820 464

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200400600800 1000 Raman Shift (cm-1) 0.6 mW 6.3 mW Intensity (a.u.)

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0 5000 1 1041.5 104200400600800 1000Intensity (a.u.)Raman Shift (cm-1)

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MoO3 High Power Low Power High Power Low Power Wavenumber (cm-1) Wavenumber (cm-1) Wavenumber (cm-1) Wavenumber (cm-1) Wavenumber (cm-1) 148 177 145 146 158 282 380* 179 179 198 377 407* 383* 384* 217 403* 451 409* 409* 245 447 464 419 424 283 622 526 453 465 338 818 565 465 529 365 992 595 528 573 379 639 570 600 471 820 599 644 666 643 723 819 765 738 996 778 767 820 780 806 821 Amorphous MoS2 Crystal MoS2

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3650 3700 3750 3800 3850 3900 3950 4000 4050 350400450500550600650Intensity (a.u.)Raman Shift (cm-1)377 cm-1402 cm-1 3800 4000 4200 4400 4600 4800 400440480520560600640Intensity (a.u.)Raman Shift (cm-1)383 cm-1408 cm-1453 cm-1 Laser line

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Discussion

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uE

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Temperature/Environment Raman Study Experimental Methods

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Results/Discussion

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0 1000 2000 3000 4000 5000 6000 200400600800 1000Intensity (a.u.)Raman Shift (cm-1) 293 K 573 K MoO3 Peak 820 cm-1 400 500 600 700 800 900 1000 250300350400450500550600Relative Intensity of 820 cm-1 band (Baseline Normalized)Temperature (K)

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200400600800 1000 1000 2000 3000 4000 5000 6000 7000 Raman Shift (cm-1) 6.3 mW 0.6 mWIntensity (a.u.)

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200400600800 1000 0 400 800 1200 1600 2000 2400 2800 3200 Raman Shift (cm-1) 6.3 mW 0.6 mWIntensity (a.u.)

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0 1000 2000 3000 4000 5000 6000 7000 8000 200400600800 1000Intensity (a.u.)Raman Shift (cm-1) 6.3 mW 0.6 mW

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riseqazza Tz ka q

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200400600800 1000 Wavenumber (cm-1) 002 Low Intensity 100 Low Intensity 100 High Intensity (Perpendicular) 002 High Intensity (Parallel) MoO3MoO3MoS2MoO3 MoS2 q k q k

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Conclusion

PAGE 113

Experimental Setup

PAGE 116

in situ Zinc (I) Wavelength E upper Ag Wavelength (nm)(m^-1) (s^-1) (nm) 510.5530784002.00E+06 4 328.2 515.3249935006.00E+07 4 330.26 521.8249942007.50E+07 6 330.29 529.2562403001.09E+05 8 334.5 578.230535001.65E+06 2 334.56 334.59 Copper (I) e e e e

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Results Initial Prototype Emission Measurements 0 500 1000 1500 2000 2500 500525550575600625650675 CO2 at 90% RH Ambient AirIntensity (a.u.)Wavelength (nm) Cu I 510.6 515.3 521.8 Cu I 529.3 Cu I 578.2 Zn II 589.4 Zn II 602.1 610.2 Zn I 636.2 Cu & Zn 2x Ambient Air CO2 @ 90% RH

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0 500 1000 1500 2000 2500 325 330 335 340 345 CO2 at 90% RH Ambient AirIntensity (a.u.)Wavelength (nm) Cu I 327.4 Zn I 328.2 Zn I 330.26 330.29 Zn I 334.50 334.56 334.59 CO2 @ 90% RH Ambient Air

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Boltzman Plot y = -1.160E-06x + 2.199E+01 R2 = 9.622E-01 y = -1.193E-06x + 2.291E+01 R2 = 9.647E-01 10 11 12 13 14 15 16 17 18 19 20 2.0E+062.5E+063.0E+063.5E+064.0E+064.5E+065.0E+065.5E+066.0E+066.5E+06 Energy Level (1/m) ln(lamda*I/(Ag)) CO2 Air 12400 K 12100 K Simple Static Spark Generated Mea surements Spark Lifetime Static Spark Generator

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-0.07 -0.06 -0.05 -0.04 -0.03 -0.02 -0.01 0 0.01 -1 10-60 1 10-62 10-63 10-64 10-65 10-66 10-6Spark Lifetime (Negative Brush)Amp (V)Time (s) -0.05 -0.04 -0.03 -0.02 -0.01 0 0.01 -1 10-60 1 10-62 10-63 10-64 10-65 10-66 10-6Spark Lifetime (Positive Brush)Amp (V)Time (s)

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Ab a CACLIUU t UUU I0 UC L UA Ub Number of Average MaxMin Std. Dev. Sparks ( s) ( s) ( s) ( s) 486.6916.340.834.35 Number of Average MaxMin Std. Dev. Sparks ( s) ( s) ( s) ( s) 605.0312.371.113.45 Number of Average MaxMin Std. Dev. Sparks ( s) ( s) ( s) ( s) 1085.7716.340.833.94 Positive Brush Negative Brush Combined Polarities

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0 5 10 15 20 25 0 4 8 12 16Negative Brush Spark Lifetime DistributionNumberLifetime Bin ( s) 0 2 4 6 8 10 12 14 048 1216 20Positive Brush Spark Lifetime DistributionNumberLifetime Bin ( s) 0 5 10 15 20 25 30 35 -2 02468 1012141618 20Combined Lifetime DistributionNumberLifetime Bin ( s)

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Atomic Spectroscopy Static Spark Generator 0 2000 4000 6000 8000 1 1041.2 1041.4 104505510515520525530535Copper (I) Atomic SpectrumIntensity (a.u.)Wavelength (nm)

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Aki gk

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0.14 0.16 0.18 0.2 0.22 0.24 0.26 0.28 490500510520530540550560Theoretical Tungsten Lamp ResponseW/cm2/nmWavelength (nm) Y = M0 + M1*x + ... M8*x8 + M9*x9 1.6512 M0 -0.0076816 M1 9.3824e-06 M2 1 R

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0 5000 1 1041.5 1042 1042.5 104505510515520525530535Theoretical and Measured Lamp Output Theoretical Irradiance (x100,000) Measured IntensityIntensity (a.u.)Wavelength (nm) 0 0.5 1 1.5 2 505510515520525530535Correction FactorWavelength (nm)

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Polarities Negative Positive Combined Average 110201111011050 Std Dev 590 740 630 Min 979097509750 Max 127001391013910 Spark Temperature Statistics (K) Brush Polarity 0 5 10 15 20 25 30 35 409250 9500 9750 10000 10250 10500 10750 11000 11250 11500 11750 12000 12250 12500 12750 13000 13250Number of SparksTemperature (K)

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Prototype Arc Measurements Arc Duration Measurements

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-0.04 -0.02 0 0.02 0.04 0.06 0.08 -5 10-70 5 10-71 10-61.5 10-6VoltageTime (sec) Negative Brush Positive Brush

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Number AverageMax Min Std. Dev. Sparks 45 0.712.140.140.48 Number AverageMax Min Std. Dev. Sparks 64 1.093.640.091.05 Number AverageMax Min Std. Dev. Sparks 109 0.933.640.090.88 Negative Brush Positive Brush Combined Polarities

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0 5 10 15 20 0 0.71.42.12.83.5Positve BrushNumberLifetime Bin ( s) 0 5 10 15 0 0.35 0.71.051.41.752.12.45NumberLifetime Bin ( s)Negative Brush 0 5 10 15 20 25 30 35 0 0.71.42.12.83.5NumberLifetime Bin ( s)Combined Polarities Atomic Emission Measurements

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-2 1050 2 1054 1056 105322324326328330332334336Intensity (a.u.)Wavelength (nm)Negative Brush Positive Brush Cu (I) 324.8 nm Cu (I) 327.4 nm Zn (I) 328.2 nm Zn (I) 330.3 nm Zn (I) 334.5 nm

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4 1048 1041.2 1051.6 105508512516520524528532Intensity (a.u.)Wavelength (nm)Neagative Brush Positive Brush Cu (I) 510.6 nm Cu (I) 515.3 nm Cu (I) 521.8 nm Zn (II) x 2 255.8 nm 528.5529529.5530530.5 Cu (I) 529.3 nm

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Be/Cu Brushes

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0 1 1042 1043 1044 1045 104200250300350400450500550600Intensity (a.u.)Wavelength (nm) Be (I) 313.04 nm Cu (I) 324.75 nm 327.40 nm 329.05 nm Cu (I) 510.55 nm 515.32 nm 521.82 nm 529.25 nm Conclusion

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Previous Research In Situ Tribo -Raman Study In situ in situ

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MoS2 Raman Study

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Arc Atomic Emission Study

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Future Research In situ in situ

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in situ in stiu