Emissivity and temperature scale for vacuum heated uranium

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Material Information

Title:
Emissivity and temperature scale for vacuum heated uranium
Series Title:
United States. Atomic Energy Commission. MDDC ;
Physical Description:
2 p. : ; 27 cm.
Language:
English
Creator:
Wahlin, H. B
Argonne National Laboratory
U.S. Atomic Energy Commission
Publisher:
Atomic Energy Commission
Place of Publication:
Oak Ridge, Tenn
Publication Date:

Subjects

Subjects / Keywords:
Uranium -- Thermal properties   ( lcsh )
Vacuum   ( lcsh )
Emissivity   ( lcsh )
Genre:
federal government publication   ( marcgt )
technical report   ( marcgt )
non-fiction   ( marcgt )

Notes

Restriction:
Date Declassified: April 7, 1947
Statement of Responsibility:
H.B. Wahlin.
General Note:
Manhattan District Declassified Code
General Note:
Date of Manuscript: September 12, 1944

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 005024670
oclc - 465276890
System ID:
AA00009338:00001


This item is only available as the following downloads:


Full Text


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MDDC 830



UNITED STATES ATOMIC ENERGY COMMISSION








EMISSIVITY AND TEMPERATURE SCALE FOR VACUUM HEATED URANIUM



by
H. B. Wahlin


Argonne National Laboratory


SI ,- '-' : "


Manuscript Date:
Date Declassified:


September 12, 1944
April 7, 1947


Its issuance does not constitute authority
for declassification of classified copies
of the same or similar content and title
and by the same author.


Technical Information Division, Oak Ridge Operations
AEC, Oak Ridge, Tenn., 10-29-48--850-12533


Printed in U.S.A.
PRICE 5 CENTS


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EMISSIVITY AND TEMPERATURE SCALE FOR VACUUM HEATED URANIUM


By H. B. Wahlin


In this investigation the true and apparent temperatures were determined for uranium which
had been heated in a vacuum of 10- mm or lower for a period of 300 hours or more.

The procedure was to take flat strips of the metal and roll them into hollow cylinders about
3 mm in diameter and 12 cm long. A hole 1,'2 mm in diameter was drilled in the side of the cyl-
inders. These were then mounted in a tube connected to a pumping system and evacuated. During
the heat treatment continuous pumping was carried on.

At the start the emissivity, calculated from the temperatures of the metal surface and the
temperature of the hole (which gives the true temperature), was higher than the final value. Con-
tinuous heating at temperatures between 1250 and 1300IK will clean the surface and lower the emis-
sivity. This cleaning, it seems, may be speeded up by turning the heating current off and allowing
the cylinder to cool through the recalescence points.

The emissivity (E) was calculated from the equation

en E 14384 1 1
.6705 TT Ta


where TT is the true and Ta is the apparent temperature, .6705 is the mean wavelength transmitted
by the red glass used in the eyepiece of the optical pyrometer.

As will be seen from the accompanying plot of emissivity against true temperature, there is a
sudden change in emissivity between the temperatures 1321 and 1323K. The cause of this change
is unknown although it may be a third crystal structure change. Such a change in emissivity with
crystal structure has been observed in iron.
The question naturally arises as to whether the metal surface is free of oxide after prolonged
heat treatment. While this cannot be answered definitely from the data, it seems that an oxide sur-
face will give a much higher emissivity. The value of .453 observed below 1321 K is lower than the
.46 obtained for clean tungsten.

The optical pyrometer readings were taken by Dr. Frances Johnson and Miss Monica Bainter,
both instructors in the Department of Physics at the University of Wisconsin. Both observers
were found to have excellent pyrometerr eyes."













MDDC 830 1











MDDC 830


Below are listed the true and apparent temperatures calculated from the emissivity data above.
R must be emphasized, however, that this temperature scale is only applicable to clean uranium
surfaces.


True
temperature

1290
1300
1310
1320

1325
1330
1340
1350
1360
1370


Apparent
temperature

1231.4

1240.5
1249.6
1258.7
1256.7
1261.2
1270.2
1279.2
1288.2
1297.1 (?)










0


END OF DOCUMENT


True
temperature

1180
1190
1200
1210
1220

1230

1240
1250
1260
1270
1280


Apparent
temperature

1130.7
1139.9
1149.1

1158.3
1167.4

1176.6
1185.7

1194.9
1204.0
1213.1

1222.2




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