A111D7 2577?

NBS SPECIAL PUBLICATION 260-89

U.S. DEPARTMENT OF COMMERCE National Bureau of Standards

Standard Reference Materials:

A Fine-Grained, Isotropic

Graphite for Use as NBS

Thermophysical Property

RM's from 5 to 2500 K
TM he National Bureau of Standards' was established by an act of Congress on March 3, 1901. The M Bureau's overall goal is to strengthen and advance the nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research and provides: (1) a

basis for the nation's physical measurement system, (2) scientific and technological services for industry and

government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau's technical work is performed by the National Measurement Laboratory, the National Engineering Laboratory, the Institute for Computer Sciences and Technology, and the Center for Materials

Science.

The National Measurement Laboratory

Provides the national system of physical and chemical measurement;

coordinates the system with measurement systems of other nations and

furnishes essential services leading to accurate and uniform physical and

chemical measurement throughout the Nation's scientific community, in- dustry, and commerce; provides advisory and research services to other Government agencies; conducts physical and chemical research; develops, produces, and distributes Standard Reference 'Materials; and provides

calibration services. The Laboratory consists of the following centers:

Basic Standards2 Radiation Research Chemical Physics

Analytical Chemistry

The National Engineering Laboratory

Provides technology and technical services to the public and private sectors to address national needs and to solve national problems; conducts research in engineering and applied science in support of these efforts; builds and maintains competence in the necessary disciplines required to carry out this research and technical service; develops engineering data and measurement

capabilities; provides engineering measurement traceability services; develops

test methods and proposes engineering standards and code changes; develops and proposes new engineering practices; and develops and improves mechanisms to transfer results of its research to the ultimate user. The

Laboratory consists of the following centers:

Applied Mathematics

Electronics and Electrical Engineering2 Manufacturing Engineering

Building Technology

Fire Research Chemical Engineering2

The Institute for Computer Sciences and Technology

Conducts research and provides scientific and technical services to aid Federal agencies in the selection, acquisition, application, and use of computer technology to improve effectiveness and economy in Government

operations in accordance with Public Law 89-306 (40 U.S.C. 759), relevant Executive Orders, and other directives; carries out this mission by managing

the Federal Information Processing Standards Program, developing Federal ADP standards guidelines, and managing Federal participation in ADP

voluntary standardization activities; provides scientific and technological advisory services and assistance to Federal agencies; and provides the technical foundation for computer-related policies of the Federal Government. The Institute consists of the following centers:

Programming Science and

Technology Computer Systems

Engineering

The Center for Materials Science

Conducts research and provides measurements, data, standards, reference

materials, quantitative understanding and other technical information funda- mental to the processing, structure, properties and performance of materials; addresses the scientific basis for new advanced materials technologies; plans

research around cross-country scientific themes such as nondestructive

evaluation and phase diagram development; oversees Bureau-wide technical programs in nuclear reactor radiation research and nondestructive evaluation; and broadly disseminates generic technical information resulting from

its programs. The Center consists of the following Divisions:

Inorganic Materials Fracture and Deformation3 Polymers

Metallurgy Reactor Radiation

'Headquarters and Laboratories at Gaithersburg, MD, unless otherwise noted; mailing address Gaithersburg, MD 20899.

2 Some divisions within the center are located at Boulder, CO 80303.
Standard Reference Materials:

A Fine-Grained, Isotropic Graphite

for Use as NBS Thermophysical

Property RM's from 5 to 2500 K

Jerome G. Hust

Center for Chemical Engineering

National Engineering Laboratory

National Bureau of Standards

Boulder, CO 80303

Sponsored by: Office of Standard Reference Materials National Measurement Laboratory

National Bureau of Standards

Gaithersburg, MD 20899

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director Issued September 1984
Library of Congress Catalog Card Number: 84-601106

National Bureau of Standards Special Publication 260-89

Natl. Bur. Stand. (U.S.), Spec. Publ. 260-89, 116 pages (Sept. 1984)

CODEN: XNBSAV

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1984 For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402
PREFACE

Standard Reference Materials (SRM's) as defined by the National Bureau of Standards are "well -characterized materials,

produced in quantity, that calibrate a measurement system to assure compatibility of measurement in the Nation." SRM's are widely used as primary standards in many diverse fields of science, industry, and technology, both within the United

States and throughout the world. For many of the Nation's

scientists and technologists it is of more than passing interest

to know the measurements obtained and methods used by the analytical community when analyzing SRM's. An NBS series of papers, of which this publication is a member, called the NBS Special Publi - cation - 260 Series is reserved for this purpose.

This 260 Series is dedicated to the dissemination of elemental concentration data for NBS biological, geological, and environmental SRM's. More information will be found in this 260 than is generally found in NBS Certificate of Analysis. This 260 enables the user of these SRM's to assess the validity of data not available in the Certificate of Analysis. We hope that

this 260 will provide sufficient additional information so that new applications of these SRM's may be sought and found. Inquiries concerning the technical content of this compilation should be directed to the authors. Other questions concerned

with the availability, delivery, price of specific SRM's should be addressed to: Office of Standard Reference Materials

National Bureau of Standards Gaithersburg, MD 20899

Stanley D. Rasberry, Chief

Office of Standard Reference Materials
OTHER NBS PUBLICATIONS IN THIS SERIES

Catalog of NBS Standard Reference Materials (1981-83 edition), R. W. Seward, ed., NBS

Spec. Publ. 260 (November 1981). Michaelis, R. E., and Wyman, L. L. Standard

Reference Materials: Preparation of White Cast

Iron Spectrochemical Standards. NBS Misc. Publ. 260-1 (June 1964). COM74- 1 1061 **

Michaelis, R. E., Wyman, L. L., and Flitsch, R., Standard Reference Materials: Preparation of NBS Copper-Base Spectrochemical Standards. NBS Misc. Publ. 260-2 (October 1964). COM74-

11063**

Michaelis, R. E., Yakowitz, H., and Moore, G. A., Standard Reference Materials: Metallographic

Characterization of an NBS Spectrometric LowAlloy Steel Standard. NBS Misc. Publ. 260-3 (October 1964). COM74-1 1060** Hague, J. L. Mears, T. W., and Michaelis, R. E., Standard Reference Materials: Sources of

Information, NBS Misc. Publ. 260-4 (February

1965). COM74- 11059

Alvarez, R., and Flitsch R., Standard Reference

Materials: Accuracy of Solution X-Ray Spectrometric Analysis of Copper-Base Alloys. NBS

Misc. Publ. 260-5 (March 1965). PB 168068**

Shultz, J. L, Standard Reference Materials: Methods for the Chemical Analysis of White

Cast Iron Standards, NBS Misc. Publ. 260-6

(July 1975). COM74-11068**

Bell, R. K., Standard Reference Materials: Methods for the Chemical Analysis of NBS

Copper-Base Spectrochemical Standards. NBS

Misc. Publ. 260-7 (October 1965). COM74-

11067** Richmond, M.S., Standard Reference Materials: Analysis of Uranium Concentrates at the

National Bureau of Standards. NBS Misc. Publ. 260-8 (December 1965). COM74-1 1066** Anspach, S. C, Cavallo, L. M. Garfinkel, S. B. Hutchinson, J. M. R., and Smith, C. N., Standard Reference Materials: Half Lives of Materials Used in the Preparation of Standard Reference Materials of Nineteen Radioactive Nuclides

Issued by the National Bureau of Standards NBS Misc. Publ. 260-9 (November 1965). COM74-11065**

Yakowitz, H., Vieth, D. L., Heinrich, K. F. J., and

Michaelis, R. E., Standard Reference Materials: Homogeneity Characterization on NBS Spectrometric Standards II: Cartridge Brass and LowAlloy Steel, NBS Misc. Publ. 260-10 (December

1965). COM74-11064**

Napolitano, A., and Hawkins, E. G., Standard Reference Materials: Viscosity of Standard

Lead-Silica Glass, NBS Misc. Publ. 260-1 1 (November 1966). NBS Misc. Publ. 260-11** Yakowitz, H., Vieth, D. L., and Michaelis, R. E., Standard Reference Materials: Homogeneity

Characterization of NBS Spectrometric Standards III: White Cast Iron and Stainless Steel Powder Compact, NBS Misc. Publ. 260-12

(September 1966). NBS Misc. Publ. 260-12** Spijkerman, J. L., Snediker, D. K., Ruegg, F. C,

and DeVoe, J. R., Standard Reference Materials: Mossbauer Spectroscopy Standard for the Chemical Shift of Iron Compounds, NBS Misc. Publ. 260-13 (July 1967). NBS Misc. Publ.

260-13**

Menis, O., and Sterling, J. T., Standard Reference

Materials: Determination of Oxygen in Ferrous

Materials - SRM 1090, 1091, and 1092, NBS

Misc. Publ. 260-14 (September 1966). NBS Misc.

Publ. 260-14**

Passaglia, E., and Shouse, P. J. Standard Refer- ence Materials: Recommended Method of Use

of Standard Light-Sensitive Paper for Calibrat- ing Carbon Arcs Used in Testing Textiles for Colorfastness to Light, NBS Misc. Publ. 260-15 (June 1967). (Replaced by NBS Spec. Publ.

260-41.) Yakowitz, H., Michaelis, R. E., and Vieth, D. L., Standard Reference Materials: Homogeneity

Characterization of NBS Spectrometric Standards IV: Preparation and Microprobe Characterization of W-20% MO Alloy Fabricated by Powder Metallurgical Methods, NBS Spec.

Publ. 260-16 (January 1969). COM74-1 1062** Catanzaro, E. J., Champion, C. E., Garner, E. L., Marinenko, G., Sappenfield, K. M., and Shields, W. R. Standard Reference Materials: Boric

Acid; Isotopic and Assay Standard Reference

Materials, NBS Spec. Publ. 260-17 (February

1970). Out of Print

iv
Geller, S. B., Mantek, P.A., and Cleveland, N.

G., Standard Reference Materials: Calibration of NBS Secondary Standard Magnetic Tape (Computer Amplitude Reference) Using the Reference Tape Amplitude Measurement

"Process A, "NBS Spec. Publ. 260-18 (November

1969). (See NBS Spec. Publ. 260-29.) Paule, R. C, and Mandel, J., Standard Reference

Materials: Analysis of Interlaboratory Measurements on the Vapor Pressure of Gold (Certifica- tion of Standard Reference Material 745). NBS

Spec. Publ. 260-19 (January 1970). PB190071**

Paule, R. C, and Mandel, J., Standard Reference

Materials: Analysis of Interlaboratory Measurements on the Vapor Pressures of Cadmium and

Silver, NBS Spec. Publ. 260-21 (January 1971). COM74- 11359** Yakowitz, H., Fiori, C. E., and Michaelis, R. E., Standard Reference Materials: Homogeneity

Characterization of Fe-3 Si Alloy, NBS Spec.

Publ. 260-22 (February 1971). COM74-1 1357**

Napolitano, A., and Hawkins, E. G., Standard

Reference Materials: Viscosity of a Standard

Borosilicate Glass, NBS Spec. Publ. 260-23 (December 1970). COM7 1-00 157**

Sappenfield, K. M., Marineko, G., and Hague, J. L., Standard Reference Materials: Comparison

of Redox Standards, NBS Spec. Publ. 260-24 (January 1972). COM72-50058**

Hicho, G. E., Yakowitz, H., Rasberry, S. D., and

Michaelis, R. E., Standard Reference Materials: A Standard Reference Material Containing

Nominally Four Percent Austenite, NBS Spec.

Publ. 260-25 (February 1971). COM74-1 1356** Martin, J. F., Standard Reference Materials:

National Bureau of Standards-US Steel Corportion Joint Program for Determining Oxygen and Nitrogen in Steel, NBS Spec. Publ. 260-26

(February 1971). 85 cents* PB 81176620

Garner, E. L., Machlan, L. A., and Shields, W. R., Standard Reference Materials: Uranium

Isotopic Standard Reference Materials, NBS

Spec. Publ. 260-27 (April 1971). COM74-

11358**

Heinrich, K. F. J., Myklebust, R. L., Rasberry, S.

D.,' and Michaelis, R. E., Standard Reference Materials: Preparation and Evaluation of SRM's 481 and 482 Gold-Silver and GoldCopper Alloys for Microanalysis, NBS Spec.

Publ. 260-28 (August 1971). COM71-50365**

Geller, S. B., Standard Reference Materials: Cali- bration of NBS Secondary Standard Magnetic Tape (Computer Amplitude Reference) Using

the Reference Tape Amplitude Measurement

"Process A- Model 2," NBS Spec. Publ. 260-29 (June 1971). COM71-50282

Gorozhanina, R. S., Freedman, A. Y., and

Shaievitch, A. B. (translated by M. C. Selby), Standard Reference Materials: Standard

Samples Issued in the USSR (A Translation from the Russian). NBS Spec. Publ. 260-30 (June

1971). COM71-50283**

Hust, J. G., and Sparks, L. L., Standard Reference

Materials: Thermal Conductivity of Electrolytic Iron SRM 734 from 4 to 300 K, NBS Spec. Publ. 260-31 (November 1971). COM71-50563**

Mavrodineanu, R., and Lazar, J. W., Standard

Reference Materials: Standard Quartz Cuvettes, for High Accuracy Spectrophotometry, NBS

Spec. Publ. 260-32 (December 1973). 55 cents* SN003-003-01213-1 Wagner, H. L., Standard Reference Materials: Comparison of Original and Supplemental

SRM 705, Narrow Molecular Weight Distri- bution Polystyrene, NBS Spec. Publ. 260-33 (May 1972). COM72-50526**

Sparks, L. L., and Hust, J. G., Standard Reference

Materials: Thermoelectric Voltage, NBS Spec.

Publ. 260-34, (April 1972). COM72-50371**

Sparks, L. L., and Hust, J. G., Standard Refer- ence Materials: Thermal Conductivity of

Austenitic Stainless Steel, SRM 735 from 5

to 280 K, NBS Spec. Publ. 260-35 (April 1972.) 35 cents* COM72-50368**

Cali, J. P., Mandel, J., Moore, L. J., and Young, D.

S., Standard Reference Materials: A Referee Method for the Determination of Calcium in Serum, NBS SRM 915, NBS Spec. Publ. 260-36 (May 1972). COM72-50527**

Shultz, J. I. Bell., R. K. Rains, T. C, and Menis,

O., Standard Reference Materials: Methods of Analysis of NBS Clay Standards, NBS Spec. Publ. 260-37 (June 1972). COM72-50692**

Richmond, J. C, and Hsia, J. J., Standard Refer- ence Materials: Preparation and Calibration of Standards of Spectral Specular Reflectance, NBS Spec. Publ. 260-38 (May 1972). COM72-

50528**

Clark, A. F., Denson, V.A., Hust, J. G., and

Powell, R. L., Standard Reference Materials The Eddy Current Decay Method for Resistivity Characterization of High-Purity Metals, NBS

Spec. Publ. 260-39 (May 1972). COM72-50529**

V
McAdie, H. G., Garn, P.D., and Menis, O., Standard Reference Materials: Selection of Thermal

Analysis Temperature Standards Through a Cooperative Study (SRM 758, 759, 760), NBS

Spec. Publ. 260-40 (August 1972.) COM72-

50776** Wood, L. A., and Shouse, P. J., Standard

Reference Materials: Use of Standard LightSensitive Paper for Calibrating Carbon Arcs Used in Testing Textiles for Colorfastness to

Light, NBS Spec. Publ. 260-41 (August 1972) COM72-50775**

Wagner, H. L. and Verdier, P. H., eds., Standard

Reference Materials: The Characterization of Linear Polyethylene, SRM 1475, NBS Spec. Publ. 260-42 (September 1972). COM72-

50944**

Yakowitz, H., Ruff, A. W., and Michaelis, R. E., Standard Reference Materials: Preparation and Homogeneity Characterization of an Austenitic Iron-Chromium-Nickel Alloy, NBS Spec. Publ. 260-43 (November 1972). COM73-50760**

Schooley, J. F., Soulen, R. J., Jr., and Evans, G. A.,

Jr., Standard Reference Materials: Preparation and Use of Superconductive Fixed Point

Devices, SRM 767, NBS Spec. Publ. 260-44 (December 1972). COM73-50037**

Greifer, B., Maienthal, E. J. Rains, T. C, and

Rasberry, S. D., Standard Reference Materials: Powdered Lead-Based Paint, SRM 1579, NBS

Spec. Publ. 260-45 (March 1973). COM73-

50226**

Hust, J. G., and Giarratano, P. J., Standard Refer- ence Materials: Thermal Conductivity and

Electrical Resistivity Standard Reference Materials: Austenitic Stainless Steel, SRM's 735 and

798, from 4 to 1200 k, NBS Spec. Publ. 260-46 (March 1975). SN003-003-0 1278-5 Hust, J. G., Standard Reference Materials: Electrical Resistivity of Electrolytic Iron, SRM 797, and Austenitic Stainless Steel, SRM 798, from 5 to 280 K, NBS Spec. Publ. 260-47 (February

1974). COM74-50176** Mangum, B. W., and Wise, J. A., Standard Refer- ence Materials: Description and Use of Precision Thermometers for the Clinical Laboratory,

SRM 933 and SRM 934, NBS Spec. Publ. 260-48 (May 1974). 60 cents* SN003-003-0 1278-5 Carpenter, B. S., and Reimer, G. M., Standard Reference Materials Calibrated Glass Standards for Fission Track Use, NBS Spec. Publ. 260-49 (November 1974). COM74-51185

Hust, J. G., and Giarratano, P. J., Standard Refer- ence Materials: Thermal Conductivity and Electrical Resistivity Standard Reference Materials:

Electrolytic Iron, SRM's 734 and 797 from 4 to 1000 K, NBS Spec. Publ. 260-50 (June 1975). $1.00* SN003-003-0 1425-7 Mavrodineanu, R., and Baldwin, J. R., Standard

Reference Materials: Glass Filters As a Standard Reference Material for Spectrophotometry;

Selection; Preparation; Certification; Use-SRM

930, NBS Spec. Publ. 260-51 (November 1975). $1.90* SN003-003-01481-8

Hust, J. G., and Giarratano, P. J., Standard Refer- ence Materials: Thermal Conductivity and Electrical Resistivity Standard Reference Materials 730 and 799, from 4 to 3000 K, NBS Spec. Publ. 260-52 (September 1975). $1.05* SN003-003-

01464-8 Durst, R. A., Standard Reference Materials: Standardization of pH Measurements, NBS

Spec. Publ. 260-53 (December 1975, Revised). $1.05 SN003-003-01551-2

Burke, R. W., and Mavrodineanu, R. Standard

Reference Materials: Certification and Use of Acidic Potassium Dichromate Solutions as an

Ultraviolet Absorbance Standard, NBS Spec.

Publ. 260-54 (August 1977). $3.00* SN003-003-

01828-7

Ditmars, D. A., Cezairliyan, A., Ishihara, S., and

Douglas, T. B., Standard Reference Materials: Enthalpy and Heat Capacity; Molybdenum

SRM 781, from 273 to 2800 K, NBS Spec. Publ. 260-55 (September 1977). $2.20* SN003-003-

01836-8

Powell, R. L., Sparks, L. L., and Hust, J. G., Standard Reference Materials: Standard

Thermocouple Materials, Pt.67: SRM 1967, NBS

Spec. Publ. 260-56 (February 1978). $2.20* SN003-003-0 18864

Cali, J. P. and Plebanski, T., Guide to United

States Reference Materials, NBS Spec. Publ. 260-57 (February 1978). $2.20* PB 277173

Barnes, J. D., and Martin, G. M., Standard Refer- ence Materials: Polyester Film for Oxygen Gas

Transmission Measurements SRM 1470, NBS

Spec. Publ. 260-58 (June 1979) $2.00* SN003-

003-02077 Chang, T., and Kahn, A. H. Standard Reference

Materials: Electron Paramagnetic Resonance

Intensity Standard; SRM 2601, NBS Spec.

Publ. 260-59 (August 1978) $2.30* SN003-

003-01975-5

vi
Velapoldi, R. A., Paule, R. C, Schaffer, R., Mandel, J., and Moody, J. R., Standard Refer- ence Materials: A Reference Method for the Determination of Sodium in Serum, NBS Spec.

Publ. 260-60 (August 1978). $3.00* SN003-003

01978-0

Verdier, P. H., and Wagner. H. L., Standard Refer- ence Materials: The Characterization of Linear Polyethylene (SRM 1482, 1483, 1484), NBS

Spec. Publ. 260-61 (December 1978). $1.70* SN003-003-02006-1

Soulen, R. J., and Dove, R. B., Standard Reference

Materials: Temperature Reference Standard

for Use Below 0.5 K (SRM 768). NBS Spec.

Publ. 260-62 (April 1979). $2.30* SN003-003-

02047-8 Velapoldi, R. A., Paule, R. C, Schaffer, R. Mandel, J., Machlan, L. A., and Gramlich, J. W., Standard Reference Materials: A Reference Method for the Determination of Potassium in Serum. NBS Spec. Publ. 260-63 (May 1979). $3.75* SN003-003-02068

Velapoldi, R. A., and Mielenz, K. D., Standard

Reference Materials: A Fluorescence Standard

Reference Material Quinine Sulfate Dihydrate (SRM 936), NBS Spec. Publ. 260-64 (January

1980). $4.25* SN003-003-02 148-2 Marinenko, R. B., Heinrich, K. F. J., and Ruegg,

F. C, Standard Reference Materials: Micro- Homogeneity Studies of NBS Standard Reference

Materials, NBS Research Materials, and Other Related Samples. NBS Spec. Publ. 260-65

(September 1979). $3.50* SN003-003-021 14-1 Venable, W. H., Jr., and Eckerle, K. L., Standard

Reference Materials: Didymium Glass Filters for Calibrating the Wavelength Scale of Spectro- photometers (SRM 2009, 2010, 2013). NBS Spec.

Publ. 260-66 (October 1979). $3.50* SN003-003-

02127-0

Velapoldi, R. A., Paule, R. C, Schaffer, R., Mandel,

J., Murphy, T. J., and Gramlich, J. W., Standard

Reference Materials: A Reference Method for the Determination of Chloride in Serum, NBS Spec.

Publ. 260-67 (November 1979). $3.75* SN003-

003-02136-9 Mavrodineanu, R. and Baldwin, J. R., Standard

Reference Materials: Metal-On-Quartz Filters as a Standard Reference Material for Spectrophoto- metry-SRM 2031, NBS Spec. Publ. 260-68

(April 1980). $4.25* SN003-003-02L67-9

Velapoldi, R. A., Paule, R. C, Schaffer, R., Mandel, J., Machlan, L. A., Garner, E. L., and

Rains, T. C, Standard Reference Materials: A

Reference Method for the Determination of Lithium in Serum, NBS Spec. Publ. 260-69 (July)

1980). $4.25* SN003-003-02214-4 Marinenko, R. B., Biancaniello, F., Boyer, P. A., Ruff, A. W., DeRobertis, L., Standard Reference

Materials: Preparation and Characterization of an Iron-Chromium-Nickel Alloy for Microanalysis, NBS Spec. Publ. 260-70 (May 1981). $2.50* SN003-003-02328-1

Seward, R. W., and Mavrodineanu, R., Standard

Reference Materials: Summary of the Clinical Laboratory Standards Issued by the National Bureau of Standards, NBS Spec. Publ. 260-71 (November 1981). $6.50* SN003-003-02381-7

Reeder, D.J., Coxon, B., Enagonio, D., Christensen, R. G., Schaffer, R., Howell, B. F., Paule, R. C,

Mandel, J., Standard Reference Materials: SRM

900, Antiepilepsy Drug Level Assay Standard, NBS Spec. Publ. 260-72 (June 1981). $4.25* SN003-003-02329-9

Interrante, C. G., and Hicho, G. E., Standard Refer- ence Materials: A Standard Reference Material Containing Nominally Fifteen Percent Austenite (SRM 486), NBS Spec. Publ. 260-73 (January

1982). $2.75* SN003-003-02386-8 Marinenko, R. B., Standard Reference Materials: Preparation and Characterization of K-411 and

K-414 Mineral Glasses for Microanalysis: SRM

470. NBS Spec. Publ. 260-74 (April 1982). $3.50 SN003-003-023-95-7

Weidner, V. R., Hsia, J. J., Standard Reference

Materials: Preparation and Calibration of First Surface Aluminum Mirror Specular Reflectance Standards (SRM 2003a), NBS Spec. Publ. 260-75 (May 1982). $3.75 SN003-003-023-99-0

Hicho, G. E. and Eaton, E. E., Standard Reference Materials: A Standard Reference Material

Containing Nominally Five Percent Austenite (SRM 485a), NBS Spec. Publ. 260-76 (August

1982). $3.50 SN003-003-024-33-3 Furukawa, G. T., Riddle, J. L., Bigge, W. G., and

Pfieffer, E. R., Standard Reference Materials: Application of Some Metal SRM's as Thermometric Fixed Points, NBS Spec. Publ. 260-77 (August 1982). $6.00 SN003-003-024-34-1

vii
Hicho, G. E. and Eaton, E. E., Standard Reference

Materials: Standard Reference Material Containing Nominally Thirty Percent Austenite (SRM)

487), NBS Spec. Publ. 260-78 (September 1982). $3.75 SN003-O03-O24-35-0 Richmond, J. C, Hsia, J. J. Weidner, V. R., and

Wilmering, D. B., Standard Reference Materials: Second Surface Mirror Standards of Specular

Spectral Reflectance (SRM's 2023, 2024, 2025), NBS Spec. Publ. 260-79 (October 1982). $4.50 SN003-003-024-47-3

Schaffer, R., Mandel, J., Sun, T., Cohen, A., and

Hertz, H. S., Standard Reference Materials: Evaluation by and ID/ MS Method of the AACC

Reference Method for Serum Glucose, NBS

Spec. Publ. 260-80 (October 1982). $4.25 SN003-

003-024-43-1 Burke, R. W., Mavrodineanu, R. (NBS retired), Standard Reference Materials: Accuracy in Analytical Spectrophotometry, NBS Spec. Publ.

260-81 (April 1983). $6.00 SN003-003-024-84-8

Weidner, V. R., Standard Reference Materials: White Opal Glass Diffuse Spectral Reflectance Standards for the Visible Spectrum (SRM's 2015 and 2016), NBS Spec. Publ. 260-82 (April 1983). $3.75 SN-003-003-024-89-9 Bowers, G. N., Jr., Alvarez, R., Cali, J. P. (NBS

retired), Eberhardt, K. R., Reeder, D. J., Schaffer, R., Uriano, G. A., Standard Reference

Materials: The Measurement of the Catalytic

(Activity) Concentration of Seven Enzymes in NBS Human Serum SRM 909, NBS Spec.

Publ. 260-83 (June 1983). $4.50 SN003-003-024-

99-6

Gills, T. E., Seward, R. W., Collins, R. J., and

Webster, W. C, Standard Reference Materials: Sampling, Materials Handling, Processing, and Packaging of NBS Sulfur in Coal Standard

Reference Materials, 2682, 2683, 2684, and 2685, NBS Spec. Publ. 260-84 (August 1983). $4.50 SN003-003-025-20-8

Swyt, D. A., Standard Reference Materials: A Look

at Techniques for the Dimensional Calibration of Standard Microscopic Particles, NBS Spec. Publ. 260-85 (September 1983). $5.50 SN003-003-

025-21-6 Hicho, G. E. and Eaton, E. E., Standard Reference Materials: A Standard Reference Material

Containing Two and One-Half Percent Austenite, SRM 488, NBS Spec. Publ. 260-86 (December

1983). $1.75* SN003-003-025-41-1 Mangum, B. W., Standard Reference Materials: SRM 1969: Rubidium Triple-Point - A Temperature Reference Standard Near 39.30 °C, NBS

Spec. Publ. 260-87 (December 1983). $2.25* SN003-003-025-44-5

Gladney, E. S., Burns, C. E., Perrin, D. R., Roelandts, I., and Gills, T. E., 1982 Compilation

of Elemental Concentration Data for NBS

Biological, Geological, and Environmental

Standard Reference Materials. NBS Spec. Publ. 260-88 (March 1984). SN003-003-02565-8

Hust, J. G., A Fine-Grained, Isotropic Graphite for Use as NBS Thermophysical Property RM's from

5 to 2500 K, NBS Spec. Publ. 260-89 (In Press).

* Send order with remittance to superintendents

of Documents, US Government Printing Office Washington, DC 20402. Remittance from

foreign countries should include an additional one-fourth of the purchase price for postage. ** May be ordered from: National Technical Information Services (NTIS). Springfield

Virginia 22151.

viii
CONTENTS

Page

1. INTRODUCTION 3

2. PHASE I. PRELIMINARY ELECTRICAL RESISTIVITY AND DENSITY CHARACTERIZATION 4 2.1 Specimen Preparation 4 2.2 Measurements 5 2.3 Results and Discussion 7 2.4 Other Graphites 14 2.5 Conclusions and Recommendations 21 2.6 Summary of Phase I 21

3. PHASE II. PRELIMINARY THERMAL CONDUCTIVITY CHARACTERIZATION .... 22 3.1 Measurements 22 3.2 Correlations 25 3.3 Conclusions and Recommendations 29

4. PHASE III. COOPERATIVE MEASUREMENTS 31 4.1 Specimen Characterization 31 4.2 Specimen Distribution and Results 32

5. PHASE IV. DATA ANALYSIS AND RECOMMENDED VALUES 52

5.1 Thermal Conductivity 52 5.2 Electrical Resistivity 75 5.3 Specific Heat 79 5.4 Thermal Diffusivity 86 5.5 Thermal Expansion 94

5.6 Seebeck Coefficient 95

6. ACKNOWLEDGEMENTS 95

7. REFERENCES 98

ix
LIST OF TABLES

Page Table 1. Resistivity and density data for AXM-5Q1 graphite

specimens 6 Table 2. Resistivity and density data for AXM-5Q and 9Q1 graphite

specimens 16 Table 3. Thermal conductivity, electrical resistivity, density and Lorenz ratio for thirteen AXM graphite specimens 24 Table 4. Densities of 30 cm long AXM-5Q1 graphite rods at 20 °C ... 33 Table 5. Summary of reported results on AXM-5Q1 graphite 51 Table 6. Thennophysical properties for AXM-5Q1 graphite as reported

by Brandt (6) 53 Table 7. Thermophysical properties for AXM-5Q1 graphite as reported

by participant 1, spec. 62, room temperature electrical resistivity = 12.40 yjrm, density = 1757 kg-m-3 53 Table 8. Thermophysical properties for AXM-5Q1 graphite as reported

by Hust (7) 54 Table 9. Thermophysical properties for AXM-5Q1 graphite as reported

by Hust (7) 55 Table 10. Thermophysical properties for AXM-5Q1 graphite as reported

by Isaacs (8), spec. 103-2, room temperature electrical resistivity = 15.49 pft'm, density = 1721 kg*m~ 3 56 Table 11. Thermophysical properties for AXM-5Q1 graphite as reported

by Maglic (9), spec. 4, room temperature electrical resistivity = 14.59 yft*m, density = 1755 kg*m~ 3 56 Table 12. Thermophysical properties for AXM-5Q1 graphite as reported

by Mirkovich (10), spec. 112B, room temperature electrical resistivity = 15.00 yft-m, density = 1724 kg-m" 3 56 Table 13. Thermophysical properties for AXM-5Q1 graphite as reported

by Moore (11), spec. 102, room temperature electrical resistivity = 12.60 yfi-m, density = 1770 kg«m" 3 57 Table 14. Thermophysical properties for AXM-5Q1 graphite as reported

by participant 5 57 Table 15. Thermophysical properties for AXM-5Q1 graphite as reported

by participant 2, spec. 41B, room temperature electrical resistivity = 18.81 yft'm, density = 1706 kg-m-3 58

x
Page Table 16. Thermophysical properties for AXM-5Q1 graphite as reported

by participant 3, spec. 52, room temperature electrical resistivity = 13.39 yfi-m, density = 1738 kg-m-3 58 Table 17. Thermophysical properties for AXM-5Q1 graphite as reported

by Taylor (12) 59 Table 18. Thermophysical properties for AXM-5Q1 graphite as reported

by Taylor (13) 60 Table 19. Thermophysical properties for AXM-5Q1 graphite as reported

by participant 4, spec. Ill-end 1, room temperature electrical resistivity = 15.00 ycrm, density = 1666 kg*m" 3 60 Table 20. Thermophysical properties for AXM-5Q1 graphite as calculated

from the equations indicated in this report, for room temperature electrical resistivity = 14.5 y£2*m~ 3 and density = 1730 kg/m3 74

xi
LIST OF FIGURES

Page

Figure 1. Electrical resistivity as a function of temperature of nine AXM graphite specimens 8 Figure 2. Electrical resistivity as a function of temperature of ten AXM graphite specimens. Four specimens taken from a single 25.4 mm diameter NBS rod and six specimens taken from a single AFML slab to illustrate short range inhomogeneity . . 9 Figure 3. Electrical resistivity as a function of temperature of twelve AXM graphite specimens 10 Figure 4. Electrical resistivity versus density of AXM graphite

specimens at 4 K (solid lines indicate intra-rod

correlation) 11 Figure 5. Electrical resistivity versus density of AXM graphite

specimens at 76 K (solid lines indicate intra-rod

correlation) 12 Figure 6. Electrical resistivity versus density of AXM graphite

specimens at 273 K (solid lines indicate intra-rod correlation) 13 Figure 7. Electrical resistivity versus density of AXM graphite

specimens at 293 K. Data obtained at SoRI prior to and after anneal at 3180 °C for one hour. Arrows point to post-anneal data 15 Figure 8. Electrical resistivity versus position along an AXM-5Q

and AXM-9Q1 graphite rod at 76 K 17 Figure 9. Density versus position along an AXM-5Q and AXM-9Q1

graphite rod at 20 °C 18 Figure 10. Electrical resistivity versus density of an AXM-5Q and AXM-9Q1 graphite rod at 76 K (illustrating short range correlation) 19 Figure 11. Electrical resistivity versus position along AXF and FXI graphite rods 20 Figure 12. Ambient -temperature, comparative thermal conductivity

apparatus for small specimens 23 Figure 13. Electrical resistivity-thermal conductivity correlation

of AXM graphite at 296 K 26 Figure 14. Lorenz ratio-density correlation of AXM graphite at 296 K 27

xi i
si

Page

Figure 15. Lorenz ratio-electrical resistivity data of AXM graphite at 296 K 28 Figure 16. Lorenz ratio-density data of FXI and AXF compared to AXM graphite values 30 Figure 17. Electrical resistivity versus position of 25.4 mm diameter

AXM graphite rods 34 Figure 18. Electrical resistivity versus position of 25.4 mm diameter

AXM graphite rods 35 Figure 19. Electrical resistivity versus position of 25.4 mm diameter

AXM graphite rods 36 Figure 20. Electrical resistivity versus position of 25.4 mm diameter

AXM graphite rods 37 Figure 21. Electrical resistivity versus position of 25.4 mm diameter

AXM graphite rods 38 Figure 22. Electrical resistivity versus position of 12.7 mm diameter AXM graphite rods 39 Figure 23. Electrical resistivity versus position of 12.7 mm diameter

AXM graphite rods 40 Figure 24. Electrical resistivity versus position of 12.7 mm diameter

AXM graphite rods 41 Figure 25. Electrical resistivity versus position of 12.7 mm diameter

AXM graphite rods 42 Figure 26. Electrical resistivity versus position of 12.7 mm diameter

AXM graphite rods 43 Figure 27. Electrical resistivity versus position of 12.7 mm diameter

AXM graphite rods 44 Figure 28. Electrical resistivity versus position of 6.4 mm diameter

AXM graphite rods 45 Figure 29. Electrical resistivity versus position of 6.4 mm diameter

AXM graphite rods . 46 Figure 30. Electrical resistivity versus position of 6.4 mm diameter

AXM graphite rods 47 Figure 31. Electrical resistivity versus position of 6.4 mm diameter

AXM graphite rods 48 Figure 32. Electrical resistivity versus position of 6.4 mm diameter

AXM graphite rods 49

xiii
Page

Figure 33. Electrical resistivity versus position of 6.4 mm diameter

AXM graphite rods 50 Figure 34. Thermal conductivity data from Hust (7) on seven AXM-5Q1

graphite specimens at 296 K 61 Figure 35. Thermal conductivity data from Hust (7) on seven AXM-5Q1

graphite specimens, six at 296 K and one specimen from 6 to 300 K 62 Figure 36. Thermal conductivity data for seven AXM-5Q1 graphite

specimens from the following participants at temperatures

from 5 to 2600 K 63 Figure 37. Thermal conductivity data for four AXM-5Q1 graphite

specimens from the following participants at temperatures

from 300 to 2600 K 64 Figure 38. Thermal conductivity deviations for seven AXM-5Q1

graphite specimens as reported by Hust (7) from

eq. (5.1.2) at 296 K 66 Figure 39. Thermal conductivity deviations for seven AXM-5Q1 graphite

specimens as reported by Hust (7) from eq. (5.1.2), six at 296 K and one at temperatures from 6 to 300 K 67 Figure 40. Thermal conductivity deviations for seven AXM-5Q1 graphite

specimens as reported by the following participants from

eq. (5.1.2) at temperatures from 5 to 2600 K 68 Figure 41. Thermal conductivity deviations for four AXM-5Q1 graphite

specimens as reported by the following participants from

eq. (5.1.2) at temperatures from 300 to 2600 K 69 Figure 42. Thermal conductivity deviations of all AXM-5Q1 graphite

data from eq. (5.1.2). Composite of Figures 38-41 70 Figure 43. Thermal conductivity deviations of all AXM-5Q1 graphite

data from eq. (5.1.2) with M

x = 1 71 Figure 44. Thermal conductivity deviations of all AXM-5Q1 graphite

data from eq. (5.1.2) with M2

= 1 72 Figure 45. Electrical resistivity data from Hust (7) on seven AXM-5Q1

graphite specimens at 296 K 76 Figure 46. Electrical resistivity data from Hust (7) on seven AXM-501 graphite specimens, six at 296 K and one specimen from 6 to 300 K 77 Figure 47. Electrical resistivity data for seven AXM-5Q1 graphite

specimens from the following participants from 5 to 2900 K 78

x iv
Page

Figure 48. Electrical resistivity deviations for seven AXM-5Q1

graphite specimens as reported by Hust (7) from

eq. (5.2.2) at 296 K 80 Figure 49. Electrical resistivity deviations for seven AXM-5Q1

graphite specimens as reported by Hust (7) from

eq. (5.2.2), six at 296 K and one at temperatures

from 6 to 300 K 81 Figure 50. Electrical resistivity deviations for six AXM-5Q1

graphite specimens as reported by the following

participants from eq. (5.2.2) at temperatures from

5 to 2500 K 82 Figure 51. Electrical resistivity deviations of all (excluding

participant 2) AXM-5Q1 graphite data from eq. (5.2.2).

Composite of Figures 48-50 83 Figure 52. Electrical resistivity deviations of all AXM-5Q1 graphite

data from eq. (5.2.2) without the correction for room temperature differences 84 Figure 53. Specific heat data for four AXM-5Q1 graphite specimens

from the following participants at temperatures from 80 to 2900 K 85 Figure 54. Specific heat deviations for four AXM-5Q1 graphite specimens

as reported by the following participants from eq. (5.3.1)

at temperatures from 80 to 2900 K 87 Figure 55.' Thermal diffusivity data for seven AXM-5Q1 graphite

specimens from the following participants from 280 to

2600 K 88 Figure 56. Thermal diffusivity data for four AXM-5Q1 graphite

specimens from the following participants from 480 to

2900 K 89 Figure 57. Thermal diffusivity deviations for seven AXM-5Q1 graphite

specimens as reported by the following participants from

eq. (5.4.1) at temperatues from 280 to 2600 K 90 Figure 58. Thermal diffusivity deviations for four AXM-5Q1 graphite

specimens as from the following participants from

eq. (5.4.1) at temperatures from 480 to 2900 K 91 Figure 59. Thermal diffusivity deviations for seven AXM-5Q1 graphite

specimens as from the following participants from

eq. (5.4.1) (without corrections for room temperature

differences) at temperatures from 280 to 2600 K 92

xv
Page

Figure 60. Thermal diffusivity deviations for four AXM-5Q1 graphite

specimens as from the following participants from

eq. (5.4.1) (without corrections for room temperature

differences) at temperatures from 480 to 2900 K 93 Figure 61. Density deviations for three AXM-5Q1 specimens as reported

by Taylor (12) from eq. (5.5.1) for temperatures from 300 to 2500 K 96 Figure 62. Seebeck coefficient data for three AXM-5Q1 graphite

specimens. Two data sets from Hust (7) at temperatures

from 5 to 300 K and one set from Moore (11) at temperatures from 80 to 800 K 97

xv i
A FINE-GRAINED, ISOTROPIC GRAPHITE FOR USE AS NBS THERMOPHYSICAL PROPERTY RM'S FROM 5 to 2500 K*

J. G. Hust Chemical Engineering Science Division

Center for Chemical Engineering

National Engineering Laboratory

National Bureau of Standards

Boulder, Colorado 80303

ABSTRACT

The Chemical Engineering Science Division (Boulder, Colorado) in conjunction

with the Office of Standard Reference Materials (Gaithersburg , Maryland) of the National Bureau of Standards, and the CODATA Task Group on Thermal Transport

Properties have investigated graphite as a potential , extended temperature range, Research Material (RM). A large number of isotropic, fine-grained graphite rods

in various diameters were obtained for these investigations.

In Phase I, electrical resistivity and density measurements were performed

on numerous rods at temperatures from 4 to 300 K. In Phase II, thermal conduc- tivity measurements were performed on thirteen specimens at about 20 °C. These measurements show that transport property variations, both between and within these rods, is relatively large (approximately 10%). However, a correlation be- tween these variables is shown to exist which will allow the calculation of thermal conductivity from simple and inexpensive electrical resistivity and den- sity measurements to within about +2%. In Phase III, a large number of specimens

were characterized for room temperature electrical resistivity and density. These measurements were in preparation for the worldwide distribution of speci- mens to participants that agreed to make thermal and electrical property measurements. Phase IV describes the results of the measurements from the various par- ticipants. Phase V describes the analysis of these data.

*This work was sponsored by the National Bureau of Standards, Office of Standard Reference Materials (NBS-0SRM), Gaithersburg, MD.

1
Key Words: characterization; density; electrical resistivity; graphite; Lorenz

ratio; Research Materials; thermal conductivity.

-2-
1. INTRODUCTION Considerable interest has been shown in establishing a fine-grained, iso- tropic graphite for use as a Research Material (RM) for thermophysical properties. Preliminary work on the Air Force Materials Laboratory-Advisory Group for Aerospace Research and Development, NATO (AFML-AGARD) program showed that graphite is a promising material. It is especially interesting because of its relatively low cost, ease of fabrication, and its wide temperature range. The AFML-AGARD program (1965 to 1975) resulted in extensive thermophysical

property measurements on several materials including graphite. These measurements have been reported in detail by Fitzer [1] and Minges [2]. The graphite

portion of that program is summarized below:

AFML-AGARD PROGRAM (1965-1975)

Material Fine-grained-isotropic graphite Ave. density = 1.757 g/cm^

10 cm dia. x 30 cm long cylinders Max. variations = +1.3%

5 cm x 10 cm x 15 cm blocks Heat treated at 2500 °C

Measurements

Property Temp. Range Variations No. of Investigators

Thermal Diffusivity 400-2600 K +7% 9 Thermal Conductivity 300-2500 K +10% 5 Thermal Expansion 300-2800 K +3% 10 Heat Capacity 1900-2800 K —- 1 Electrical Resistivity 400-2600 K +4% at 1300 K 2

It was concluded as a result of the program that this graphite is very promising,

but that further work should be performed. The remaining stock of this AFML

material was donated to NBS for further study and/or use. The remaining quantity

of material, however, was quite limited. Unfortunately, also, the specimens that

-3-
were distributed to participants of the program were neither individually charac- terized prior to measurement, nor were they collected after measurement for postcharacterization. Because of this, NBS decided to purchase a supply of the same fine-grained graphite (AXM-5Q1) for further study. To establish a reasonable

supply, 400 6.4 mm diameter rods, 150 12.7 mm diameter rods, and 70 25.4 mm diam- eter rods were purchased. All rods are 30 cm in length. In addition, some AXM5Q and AXM-9Q material was purchased for research purposes. This material was specified to have a density in the range 1.72-1.75 g/cm3

. This fine-grained graphite is produced by molding into blocks or plates.

Rods are then cut and machined from the blocks. Petroleum coke is the source of the graphite, and the final graphitization is performed at 2500 °C, or in the case of the 9Q material at 2900 °C. Further preparation details are considered

proprietary by the supplier. The supplier indicated that the most homogeneous

product will come from relatively thin plates. These rods were machined from

5 cm x 10 cm x 30 cm plates.

2. PHASE I - PRELIMINARY ELECTRICAL RESISTIVITY AND DENSITY CHARACTERIZATION

2.1 Specimen Preparation

To perform electrical resistivity and density measurements, specimens of 6.4 mm diameter and 50 mm length were required. Rods were randomly selected from

the 6.4 mm diameter rods and notched with a code indicating the pack and rod from which they came. The code is a three digit number corresponding to the number of notches on each end and on the side near end 1, i.e., 1st digit = notches on end no. 1, 2nd digit = notches on end no. 2, 3rd digit = notches on side no. 1. Rods 50 mm in length were cut from the 25.4 mm diameter rods. These were quar- tered and machined to 6.4 mm diameter rods. Also some scrap blocks from the AFML-AGARD material were machined to 6.4 mm diameter specimens for intercom- parison with the new rod material. A total of 39 specimens were prepared: 21 from

-4-
the 6.4 mm diameter rods, 12 from three 25.4 mm diameter rods, and six from a single slab of AFML material.

2.2 Measurements

All electrical resistivity measurements were performed with four-terminal

D.C. potentiometric apparatus. The imprecision of this apparatus is estimated at +0.5%. (For inhomogenei ty determinations the imprecision, not the uncertainty,

is paramount). Electrical resistivities were determined at 4 K, 76 K, and 273 K on most of the specimens. Some of the specimens were measured only at 76 K. Densities were first calculated from air weight-volume measurements. This

was done because it was suggested that the usual hydrostatic weighing technique

could not be used on graphite. This seemed reasonable because it was assumed

that the graphite would absorb water and give incorrect bulk densities. After

the initial tests, hydrostatic weighings to check the previous statement were performed. Surprisingly, the hydrostatic weighing method yielded results en- tirely consistent with the air weight-volume method. No water absorption was ob- served during the measurements. The densities reported here are, therefore, based on the hydrostatic weighing method which is considered to yield more pre- cise results. All density measurements were performed at ambient temperature,

approximately 20 °C. These measurements are estimated precise to +0.1%. After the NBS-Boulder electrical resistivity and density measurements, re- corded in Table 1, a group of seventeen specimens was selected from the 39 specimens. These were sent to Mr. Pears of Southern Research Institute (SoRI) for an- nealing at 3180 °C (5750 °F). Mr. Pears suggested that the variability in den- sity and electrical resistivity could be considerably reduced after such an anneal. The electrical resistivities and densities were measured at 20 °C both prior to and after the 3180 °C anneal at SoRI. These results are also listed in Table 1. It is noted that the densities of NBS and SoRI agree quite well and the

-5-
Table 1. Resistivity and Density Data for AXM-5Q1 Graphite Specimens.

Specimen Identification

4

P-i/- 76

yft«m 273

y£l«m

Density*

NBS,

3 g/ cm

Density

SoRI

(vre)

p 293 SoRI

(Pre;

Density

SoRI

(Post)

p 293

SoRI (Post)

100 29.42 24.02 15.23 1.755

200 AFML Scrap 29.28 23.92 15.27 1.751 300 blocks 29.91 24.47 15.67 1.742 1.741 14.59 1.747 11.58

400 (6.4 mm dia) 29.35 23.91 15.21 1.754 1.752 14.56 1.746 11.46

500 29.15 23.67 15.08 1.754 600 28.50 23.27 14.85 1.765 1.757 14.03 1.757 11.16

101 Rod 28.59 23.28 14.81 1.721 1.720 13.96 1.717 12.74

201 No. 1 29.51 24.10 15.32 1.706

301 28.93 23.57 15.07 1.713 1.713 14.32 1.709 12.74

401 29.60 24.12 15.29 1.707 1.705 14.85 1.703 13.19

102 AXM-5Q1 26.52 21.24 13.12 1.751 202 Rod P0C0 26.87 21.52 13.27 1.749

302 No. 2 25.4 rim to 27.06 21.69 13.49 1.746

402 6.4 mm dia 26.65 21.34 13.25 1.752

103 29.63 24.20 15.49 1.721 203 28.90 23.58 14.99 1.735

303 28.90 23.55 15.00 1.734

403 29.45 24.04 15.34 1.722

110 Rod end a 28.23 23.04 14.74 1.732

210 No. 1 b- 26.46 21.47 13.53 1.782 1.783 12.95 1.781 12.20

310 Rod No. 2 AXM-5Q1 33.80 28.12 18.56 1.698

111 Pack 1A 22.30 1.768

121 Rod 23.35 1.750 1.744 14.30 1.748 13.48

131 No. 1 24.69 1.721 1.722 15.30 1.720 14.27

141 23.94 1.732

151 Rod No. 1 31.94 26.06 16.61 1.727 1.732 15.80 1.730 13.12

211 Rod No. 2 Pack 29.77 24.12 15.20 1.709

311 Rod end a 2A 32. 28 26.66 17.27 1.709 1.713 16.42 1.711 13.98

411 No. 3 b 28.22 23.02 14.67 1.775 1.778 14.09 1.775 12.19 152 Rod end a 32.00 26.14 16.68 1.697 1.700 16.18 1.697 13.28

212 No. 1 b 29.41 23.78 14.99 1.716 312 Rod No. 2 30.55 25.13 16.26 1.747 412 Rod No. 3 Pack 31.40 25.95 16.80 1.725 1.723 16.12 1.720 14.15

112 3A 25.22 1.706

122 Rod 24.65 1.717 1.719 14.86 1.717 12.76

132 No. 1 24.17 1.724

142 23.91 1.728 1.727 14.34 1.725 12.50

113 Rod No. 1 Pack 4A 29.34 23.99 15.38 1.727

104 Rod No. 1 Pack 5A 31.38 26.22 17.31 1.751 1.753 16.49 1.748 12.94

*A11 NBS densities measured near 20 °C.

-6-
effect of the high temperature anneal is small on density. However, the electrical resistivities were affected considerably by the anneal.

2.3 Results and Discussion

To determine the consistency of the NBS measurements and the SoRI measurements, graphs were made of the resistivity as a function of temperature. These

plots, Figures 1, 2, and 3 illustrate several important points. First they con- firm a measurement imprecision of near +0.5%. (They also indicate a comparable

accuracy). These plots also indicate that the differences between specimens are temperature independent to within the measurement imprecision from 4 to 300 K. Since the SoRI measurements were performed at 293 K and the NBS measurements were

done at 4, 76, and 273 K, direct intercomparison is not possible. However, these

plots show excellent correspondence between the two sets of data.

The second set of plots, Figures 4, 5, and 6 illustrate the dependence of electrical resistivity on density at 4, 76, and 273 K, respectively. The lines drawn on these figures show the resistivity-density correlation for groups of specimens coming from single rods or plates. As can be seen, very strong correlation (intra-rod correlation) exists for such groups. It is also clear that the electrical resistivity -density correlation between such groups (inter-rod correlation) is very weak. Obviously electrical resistivity is strongly dependent on density but also on a density independent parameter which varies from rod-to-rod

but is fairly constant within each rod. This may be related to the chemical purity, the degree of graphitization, or the void (vacancy) concentration and distribution of each rod. At this time, the source of these inter-rod differences are not clear. The intra-rod correlation corresponds to a four percent

change in electrical resistivity per one percent change in density at all tem- peratures.

-7-
0 100 200 300

TEMPERATURE, K

Figure 1. Electrical resistivity as a function of temperature of nine AXM

graphite specimens.

-8-
33

31

TEMPERATURE, K

Figure 2. Electrical resistivity as a function of temperature of ten AX^ graphite specimens. Four specimens taken from a single 25.4 mm diameter NBS rod and six specimens taken from a single AFML slab

to illustrate short range inhomogeneity.

-9-
TEMPERATURE, K

Figure 3. Electrical resistivity as a function of temperature of twelve AXM graphite specimens.

-10-
ui Uri 'A1IAI1SIS3U nV0IU103n3

-11-
M

•O

COc

CDEO

O)Q.

OO

(U +J-c

Cl

ro c

S- 0

CT> 21 ia X<

r a>

s- 4— s- O 0

>>

+J T30

00 S_ C

<D fO T3 s-

+-> 00

=300

s~ CD

(D +-> >

u

>>

+J -a

!= >

+-> 00

00 a>e

CO

CD$_ -0

"fOu 'o

CO

z.

O) dl

w 'A1IAI1SIS3H nV0l«10313

-12-

Figure 7 illustrates the resistivity-density data taken at SoRI . The arrows between pairs of data points are directed from the preanneal to the post-anneal

data. The average change in density was about 0.2%, and the average change in resistivity about 15%. No significant improvement in homogeneity is observed as

a result of the 3180 °C anneal. The intra-rod electrical resistivity-density

correlation also remained the same after the high temperature anneal. It is clear that a high temperature anneal is necessary to stabilize the specimens for use above 2500 °C; but, it is also clear that such an anneal does not appreciably

improve the homogeneity.

In addition to the above described results on AXM-5Q1, several measurements

were performed on one rod of AXM-9Q1 and one rod of AXM-5Q. Each of these rods were cut into six specimens. The densities and electrical resistivities of these specimens are listed in Table 2 and plotted in Figures 8 and 9. These figures

show a uniform change in property from one end of the rod to the other. Figure 10 shows the electrical resistivity versus density correlation for these

two rods. Again a strong correlation is observed and the value of the slope is in agreement with the results from the AXM-5Q1 measurements.

2.4 Other Graphites

Three rods of AXF-5Q material and two rods of spectroscopic purity graphite,

designated as FXI material, were obtained for measurement. The FXI material is higher purity and density than the AXF and AXM material. The average density of each of the five rods and the resistivity as a function of position along these

rods at 2.5 cm intervals was measured. These data are illustrated in Figure 11. The results show that the intra-rod variability in electrical resistivity for the AXF material is about 13%, and the inter-rod variability is about the same. These results are comparable to those obtained with the AXM material. The results

on the spectroscopic purity rods show the rate of change in resistivity as a

-14-
o

oo Oc co

QJ i—

. E 01 U -P

CD (O D.

CO 1

(O

CD OJ

4-> E

r- E

.e re 0.

re s_

S_ CD <o

+-> M— ro 21 (O -O X

< -DE <o M— <0 QJ O E O C

CO

1 •1- S- +-> 00 O 00 E •!- 0

cd s- Q- -O Q- O

00 1—

4-> 00 0 +-» S- C/0 C > +-> O

Q. >>

+J -0 to

•i- O) S > e O

S-

+-> to S- w +J < •r- _Q

00 0

a>

i- (O S- +J 1— (O O

rO 0 -E O

a> z. • E

4-> 0 0

<u ro s- 1— CT> 0

LU C\J <+-

Is- co lo *r co cm ut-iyri 'A1IAI1SIS3H lV0mi0313

-15-
Table 2. Resistivity and Density Data for AXM-5Q and 9Q1 Graphite Specimens.

Specimen P76K Density

-3 Identification y^«m g«cm

410 19.64 1.724

510 Pack 6A 19.18 1.734

610 AXM-9Q1 18.93 1.736

220 (Rod 1) 18.95 1.737

320 18.71 1.742

420 19.15 1.731 520 | 21.32 1.739

620 Pack 7A 21.55 1.733

330 AXM-5Q 22.01 1.721 430 (Rod 1) 22.49 1.716

530 23.01 1.708

630 23.15 1.696

-16-
Figure 8. Electrical resistivity versus position along an AXM-5Q and AXM-9Q1

graphite rod at 76 K.

-17-
E

u

1.75

1.74

1.73

>: 1.72

t/J LU

o

1.71

1.70

1.69

\ AXM-9Q1\

\

/ \

\

AXM-5Q \

V

\

\

\\

I I 0 I 10 15 20 25 30

POSITION ALONG ROD, cm

Figure 9. Density versus position along an AXM-5Q and AXM-9Q1 graphite

rod at 20°C.

-18-
-19-
16

E15

a

H

>14

H

CO

</> yj

ec_|13

<

o

cr

i-o

w 12

LU

11

r

DENSITY 1.817 g/cm3 THESE DATA ARE

PLOTTED IN REVERSE - ORDER OF POSITION TO

OBTAIN CONSISTENCY

DENSITY = 1.835 g/cm3

y DENSITY = 1.876 q/cm3

O- AXF-5Q-I - AXF-5Q-II

A — AXF—5Q— III + - FXI-I • - FXI-II

DENSITY = 1.922 g/cm3 NOTCHED END

DENSITY = 1.910 g/cm3

I L

5 10 15 20

POSITION ALONG ROD, cm

25

Figure 11. Electrical resistivity versus position along AXF and FXI graphite rods.

-20-
function of position (i.e., slope of p vs X) is of comparable magnitude. How- ever, these rods were only 15 cm long compared to 30 cm for the AXF material, and therefore the total change was not as great for the FXI material. The difference

between the two FXI rods is near 10% in resistivity. Thus it appears that neither of these materials is better than the AXM material from a homogeneity

standpoint.

2.5 Conclusions and Recommendations

The inhomogeneity in electrical resistivity of these graphite rods is dis- couragingly high. It is clear that this lot of graphite cannot be used as an electrical resistivity SRM without characterizing each rod. If the thermal con- ductivity correlates with electrical resistivity, as expected, the same state- ments are applicable to thermal conductivity. Thermal expansion and specific

heat are not expected to be sensitive to these inhomogeneities and, therefore,

this lot of graphite may be acceptable for these properties. Because of the merits of using graphite for various RM's, it was recommended

that further work be done on this lot of graphite to investigate the thermal conductivity-electrical resistivity-density correlations. This work represents

Phase II of this investigation.

2.6 Summary of Phase I

1. The inhomogeneity in electrical resistivity (and of thermal conductivity

by association) of this lot of graphite rods is excessively high for use as SRM's, unless each piece is certified.

2. A strong intra-rod correlation exists between electrical resistivity and density. This correlation is practically non-existent over this range of den- sities for inter-rod specimens.

-21-
3. Annealing the specimens at 3180 °C produces an average decrease of 16%

in electrical resistivity and 0.2% in density, but statements (1) and (2) above

are still applicable to essentially the same degree for the annealed specimens.

4. The electrical resistivity-density correlation is essentially the same for AXM-5Q1, AXM-5Q, and AXM-9Q graphite.

5. The validity of the above statements is independent of temperature (from

4 to 300 K). Therefore, subsequent homogeneity characterization measurements are conducted at ambient temperature.

6. Further work is recommended to investigate the thermal conductivityelectrical resistivity-density correlation and the feasibility of characterizing

each specimen of graphite for SRM use.

3. PHASE II. PRELIMINARY THERMAL CONDUCTIVITY CHARACTERIZATION

3.1 Measurements

A series of ambient temperature thermal conductivity measurements with com- parative apparatus was completed. This comparative apparatus is schematically

illustrated in Figure 12. Prior to the measurements on graphite, a series of runs on two specimens of electrolytic iron (SRM-1463) was conducted to ascertain

the accuracy and precision of this apparatus. These measurements showed that the

thermal conductivity results are precise to within +1% with no measurable sys- tematic bias. The thermal conductivity of thirteen graphite specimens was measured

covering the entire range of electrical resistivity and density of the previously

characterized specimens. Replicate runs were performed to further study the im- precision of the comparative apparatus. These measurements confirm our estimate

of imprecision with this comparative apparatus to be +1% for thermal conductivity. The measured results on the thirteen graphite specimens are listed in Table 3.

-22-
INSULATION

rfti

SRM -

SPECIMEN

(INDIUM ONBOTH ENDS)

LINEAR BEARINGS

a

c

BRASS PLATE

(TYP>

TEMPERATURE

CONTROL

COILS

THERMOCOUPLES

PUSH-ROD

STRUCTURE &

ALIGNING BOLTS

& NUTS (TYP)

BELLOWS

PRESSURIZING PIPE VACUUM PIPE

Figure 12. Ambient- temperature, comparative thermal conductivity apparatus

for small specimens.

-23-
Table 3. Thermal Conductivity, Electrical Resistivity, Density, and Lorenz Ratio for Thirteen AXM Graphite Specimens.

•JQ nop |Jc?L i1 man lllcril Identification

j

(k)

X (W*m"l'K~l)

PI opt vi m~\ &

l\Co 1 Jl IV 1 LJr (ufi*m) 6.4 mm spec

( n • r*m — 3 \ \y cm ; 5 cm spec

Lorenz

Rati o

( 10"8v2«K"2)

310-0 296.0 72.8 17.5 1.693 1 .698 430

296.2 72.2 17.5 426 296.7 73.2 17.5 ii " 432

310-1 296.8 73.0 17.5 1.689 430 310-2 296.7 73.7 17.5 1.690 ii 435

310-3 296.9 73.8 17.5 1.698 435

310-4 296.4 74.4 17.5 1.702 ii 439

520 295.6 106.4 12.9 1.731 1.739 464

ii 295.8 104.9 12.9 457 296.7 105.7 12.9 460 400 296.3 121.9 11.3 1.755 1.746 465 296.4 121.1 11.3 462

410 296.2 120.0 11.6 1.736 1.724 470

296.6 118.0 11.6 461 102 296.4 112.6 12.6 1.755 1.751 479

296.8 112.8 12.6 479

401 296.2 102.5 13.0 1.716 1.703 450

296.4 102.7 13.0 450

100 297.0 97.0 14.4 1.755 1.755 470

311 296.5 95.1 13.9 1.722 1.711 446

312 296.9 92.5 15.3 1.757 1.747 476

a These measurements were performed on 50 mm long specimens from which the 7 mm specimens

were obtained. "These densities are for T = 293 K and not for the listed temperature.

-24-
The thermal conductivities have a mean of 96.5 W«m~l K" 1 with a range of 72 to 122 or about +25%. The electrical resistivities have a mean value of 15.0 yft*m, and range from 11.3 to 17.5 or about +20%. The mean of the Lorenz ratios, pA/T,

is 453 x 10'8

V

2 K~ 2 with a range from 426 to 479 or about +6%. Figure 13

is a plot of electrical resistivity versus thermal conductivity and clearly il- lustrates their interdependence.

3.2 Correlations

In Phase I, a strong intra-rod correlation of electrical resistivity and density, but hardly any inter-rod correlation, was reported. The above results suggest the same would be true of thermal conductivity and density. A plot was made of these variables which shows this to be the case. The possibility of a Lorenz ratio dependence on electrical resistivity or density was investigated.

Figures 14 and 15 are plots of Lorenz ratio versus these variables. Figure 14 indicates that Lorenz ratio at ambient temperature is a linear function of density. The equation for this relationship is L = -582 + 600*d,

with d in g/cm3

. The total range of deviations in L from this line is +2%. This is within the combined experimental error of determining L and d. Thus, for these specimens it would be possible to predict thermal conductivity to better

than 2% at ambient temperature from measurements of electrical resistivity and density. The densities used here are based on simple volumetric and weight meas- urements on the 6.4 mm diameter specimens. The agreement of the data with the line in Figure 14 is consistent with the combined imprecision and uncertainty of the various measurements. The imprecision in the measurement of \ is estimated

to be +1%, and the imprecision in the measurement of p is estimated to be about

+0.5%. Thus the imprecision in L is about +1.5%, since the imprecision in mea- suring T is negligible. Note that the uncertainty in determining A and p, caused

-25-

-27-
10 11 12 13 14 15 16 17 18

ELECTRICAL RESISTIVITY, ^Q, m

Figure 15. Lorenz ratio-electrical resistivity data of AXM graphite at 296 K.

-28-
by the form factor determinations, cancels in the calculation of L. The uncer- tainty in measuring density on these specimens is estimated to be about +0.8%.

The corresponding ellipse of imprecision and error band are shown in Figure 14, and it is noted that none of the data points lie outside the estimated error

band. A preliminary result of a single measurement performed at ORNL (Peyton

Moore, Private Communication) is included in Figure 14, and is in excellent agreement with the MBS measurements.

The scatter of the data points in Figure 15 is large enough that one cannot

be sure of any Lorenz ratio dependence on electrical resistivity. In an ORNL re- port by McElroy, et al . [3] an equation is given describing the observed rela- tionship between thermal and electrical conductivities for a group of graphite

specimens with resistivities ranging from 5 to 100 yn*m. This equation reduces to L = (1.56 x 10 -3 - 2.66 x 10 _9

/ P )/T and is shown on Figure 15. The agreement of this line with the average of our data for resistivities from 11 to

18 yft*m is good, but the trend with respect to p is inconsistent with our data. However, McElroy indicated that their equation described their data to within +8%

and our data fall within that range. The Lorenz ratio-density behavior of the AXF and FXI materials was also in- vestigated. Lorenz ratio results for these five specimens deviate by as much as 16% from the line obtained for the AXM material , as shown in Figure 16. 3.3 Conclusions and Recommendations

The work described in Phase II shows that it is possible to characterize

this lot of graphite, including AXM-5Q1 as received, AXM-5Q1 after anneal at 3180 °C, AXM-5Q and AXM-9Q1 , to obtain ambient temperature thermal conductivity

values accurate to better than +2% using simple electrical resistivity and density measurements on each specimen. It is now believed that graphite material

-29-
1.60 1.70 1.80 1.90 2.00

DENSITY, g em 3

Figure 16. Lorenz ratio-density data of FXI and AXF compared to AXM graphite values.

-30-
which is sufficiently homogeneous in transport properties to avoid individual specimen characterization is not available. The inhomogeneities can be reduced through a selection process, but this will necessitate the type of characterization described above. Further evidence that our inhomogenei ty results based on electrical resistivity measurements are not atypical is found in a report by Wilkes [4]. This report is the result of an investigation on the effects of radiation on the transport properties of graphite materials. As part of this research, the electrical resistivity changes along the lengths of numerous rods were determined.

Changes on the order of 1%/cm were not uncommon. Such changes are comparable to those observed on the rods reported here. Although the correlation between L and d reported here for ambient temperature is highly encouraging; considerable research still needs to be performed be- fore we can be certain that the correlation applies to the entire temperature

range.

4. PHASE III - COOPERATIVE MEASUREMENTS

In view of the encouraging result found in Phase I and II, that thermal con- ductivity could be accurately predicted at room temperature from simple electrical resistivity and density measurements, the decision was made to proceed

with wide-scale cooperative measurements at temperatures from 4 to 3000 K. This phase of the program was conducted in cooperation with the CODATA Task Group on Thermophysical Properties. Dr. M. Minges of the Air Force Materials Laboratory,

Dayton, Ohio was instrumental in organizing this phase. For an overall description of this effort, including other SRM's, see reference 5. 4.1 Specimen Characterization

In preparation for the specimen distribution, a large number of rods were characterized for electrical resistivity and density. This step was completed

-31-
with the measurement of 50 rods of each available diameter (6.4, 12.7, and 25.4 mm). The average densities of these rods are presented in Table 4. These

rods were notched and assigned numbers as follows: The "one's" digit was notched

in the side of end 1, the "ten's" digit was notched on end 1, and the "hundred's" digit was notched on end 2. The one's digit was never "zero", so end 1 is always

uniquely defined. The 1500 measured electrical resistivities as a function of position along these specimens are plotted in Figures 17 through 33. Since the variation of resistivity along each rod was of primary interest, no attempt was made to measure all of these rods at exactly the same temperature. The measurements were conducted in a thermally lagged box which slowly varied in temperature

with room conditions. The box temperature for each set of measurements is indi- cated in parentheses on Figures 17 through 33. The temperature in the box,

during the measurement of each specimen, remained constant to within 0.05 °C. The most homogeneous of these specimens will be used for transport property

SRM's. Corrections to a fixed temperature (say 20 °C) can be made by using the slope indicated in Figures 1, 2, and 3, 0.034 yft*m/K. In all cases, the cor- rection to 20 °C is less than 1%. 4.2 Specimen Distribution and Results

Dr. Minges (AFML) arranged the participation of 18 experimentalists from around the world. Specimens were prepared to the desired approximate sizes and distributed to these participants. When possible, further electrical resistivity

and density characterization measurements were performed at NBS on the actual specimens distributed. In some cases, adjacent pieces were characterized.

Nearly all of the participants that were able to report results also published

their results in the open literature and are listed in the references. Up to the present time, some reported their results only to the committee, and these will

be referred to as participant 1, 2, etc., to maintain confidentiality. A summary

of the reported results and pre-characteri zation data is given in Table 5.

-32-
Table 4. Densities of 30 cm long AXM-501 graphite rods at 20°C.

Specimen

. 3 Density, g/cm Identification

7, T- 1 6.4 mm dia 12.7 mm dia 25.4 mm dia

001 1 . 695 1 . 71

1 . 696 002 1 .729 1.715 1 .728 003 1 .733 1 . 731 1 . 727 004 1 .733 1 .722 1 .728 005 1 .753 1 .726 1 .720 006 1 .736 1 .718 1 .709

011 .732 1 .728 1 .704 012 1 .737 1 .725 1 . 706

011 .734 1 .753 1 .728 014 1 .734 1 .737 1 .718

011 .736 1 . 737 1 . 709

01

1 . 746 1.717 1.710

021 1 .734 1 .735 1 .722 noo \JCL 1 701 1 . 15 \ 1 . 743 1 7/11 023 1 .734 1 .718 1 . 732

no/i 1 7/10

1 . I'M 1 7/11 1 70C 1 . / -3D 025 1 .739 1 . 769 1 .709 noe 1 . 744 1 7/10 1 700 1 . / 5d

031 1 .725 1 . 738 1 .728 noo U5d 1 700 1 70Q 1 . / do 1 71 C

(151 U55 1 7/17 1 7/10 1 . 1 Qd i 7nc 1 . / UD

no/i 1 700 \ . 1 CO 1 7/1 K 1 701 1 . / 5 1 noc Uoo i 7on 1 . / oil 1

\ . 171 1 5 1

1 790 036 1 . 739 1 719 1 . / 5d 1 71 n 1 . / 1 U

n/i i 1 717 1 . / 1 /1 70f1 1 . / dU 1 717 1 . / 1 / 042 1 . 750 1 . 743 1 .71 1 043 1 .739 1.712 1 . 706 044 1 . 741 1 . 744 1 .728 045 1.719 1 . 744 1 .739 046 1 .743 1 .709 1 . 737

051 1 .746 1 .726 1 .735 052 1 .637 1 . 709 1 .726 053 1 . 754 1 . 725 1 . 729 054 1 .737 1 .740 1 .71

055 1 .749 1 . 740 1.716

056 1 .736 1 .725 1.710

nei Ub 1 1.717 1 . 725 1 .735 062 1 .748 1 .742 1.723

063 1 .749 1 .731 1 .718 064 1 .737 1 .728 1.732

065 1 .762 1 .738 1 .708 066 1 .754 1 .723 1 .727

101 1 .726 1 .727 1 .739 102 1 .722 1 .727 1 .731 103 1 .709 1 .728 1 .740 104 1 .747 1 .742 1 .746 105 1 .719 1 .714 1 .741 106 1.720 1.731 1.733

111 1.730 1.728 1.737

112 1.719 1 .724 1 .745

-33-
15

T

POSITION, cm

Figure 17. Electrical resistivity versus position of 25.4 mm diameter AXM graphite rods.

-34-
Figure 18. Electrical resistivity versus position of 25.4 mm diameter AXM graphite rods.

-35-
POSITION, cm

Figure 19. Electrical resistivity versus position of 25.4 mm diameter

AXM graphite rods.

-36-
POSITION, cm

Figure 20. Electrical resistivity versus position of 25.4 mm diameter AXM graphite rods.

-37-
I 10 15

~ 20 ' 25

POSITION, cm

Figure 21. Electrical resistivity versus position of 25.4 mm diameter AXM graphite rods.

-38-
5 10 15 20

POSITION, cm

Figure 22. Electrical resistivity versus position of 12.7 mm diameter AXM graphite rods.

-39-
10 15 20

POSITION, cm

Figure 23. Electrical resistivity versus position of 12.7 mm diameter AXM graphite rods.

-40-
10 15 20 25

POSITION, cm

Figure 24. Electrical resistivity versus position of 12.7 mm diameter AXM graphite rods.

-41-

5 10 15 20

POSITION, cm

Figure 26. Electrical resistivity versus position of 12.7 mm diameter

AXM graphite rods.

-43-
POSITION, cm

Figure 27. Electrical resistivity versus position of 12.7 mm diameter AXM graphite rods.

-44-
POSITION, cm

Figure 28. Electrical resistivity versus position of 6.4 mm diameter AXM graphite rods.

-45-
5 TO 15 20 25

POSITION, cm

Figure 29. Electrical resistivity versus position of 6.4 mm diameter

AXM graphite rods.

-46-
10 15 20

POSITION, cm

Figure 30. Electrical resistivity versus position of 6.4 mm diameter AXM graphite rods.

-47-
T T

5 10 15 20 25

POSITION, cm

igure 31. Electrical resistivity versus position of 6.4 mm diameter AXM graphite rods.

•48-
T

5 10 15 20 25

POSITION, cm

Figure 32. Electrical resistivity versus position of 6.4 mm diameter

AXM graphite rods.

-49-

Table 5. Summary of reported results on AXM-5Q1 graphite.

raiJ, 1 C 1 pant

([xer.) Daf Y

"fc D v*r\ t~\a v*"f" 1 ^ c rroperti es rieasurea lemperauure

Kange \\)

Characterization Data Electrical Density Resistivity

(g/cm3

) (vfl'm)

Brandt (6) D 1100-2315 1.733 14.31 Brandt (6) D 1085-2240 1.723 14.88

Hust (7) X,p,S 4-300 1.728 12.58

Hust (7) X,p,S 4-300 1.722 14.46 Hust (7) —13 specimens X »p 296 only 16.9 to 17.6 11.3 to 17.5 Isaacs 1 (8) c 83-290 1.721 15.49 Maglic (9) D 480-1713 1.755 14.59 Mirkovich (10) D 273-1073 1.724 15.00 Moore (11) X,S 80-950 1.770 12.60 Taylor (12) X ,p ,C ,a,D 400-2400 1.744 13.80 Taylor (12)

ii " 1.789 13.00 Taylor (12)

n 300-2500 1.698 14.40 Taylor (13) X,D 530-2933 1.751 13.12 Taylor (13)

n 481-2247 1.707 15.29 Participant 1 C 373-873 1.757

rdf L 1 L 1 pall t 1 p »^ 1.706 18.81 Participant 3 X,p 300-2100 1.738 13.39 Participant 4 D 553-2460 1.666 15.00 Participant 4 D 593-1343 1.666 15.00 Participant 5 X 363-1067 1.696 14.20 Participant 5 X 343-1124 1.708 13.50 Participant 5 X 1085-2605 1.717 13.91 Participant 5 X 1077-2615 1.716 14.40

*D = thermal diffusivity, x = thermal conductivity

p = electrical resistivity, a = thermal expansion, C = specific heat

S = Seebeck coefficient

-51-
The data from the participants are reported in various forms. Some data are

in SI units and others are in British units, some are corrected for thermal ex- pansion and others are not, some are closely-spaced direct experimental values

and others are more widely-spaced smoothed values. To achieve sets of data for convenient comparison and representation, the following modifications were per- formed:

1. All data were converted to SI units.

2. All data known to be uncorrected for thermal expansion were corrected

with the following equations:

X = xobs

/(i + AL/L)

p = P0bs

(l + AL/L)

D = Dobs (l + AL/L)2

The values for aL/L were taken from Touloukian et al . (14). The cor- rections amount to -0.2% at 0 K, 0% at 293 K, and 2.1% at 2600 K. 3. When very closely-spaced data were reported, a subset was selected that

a) covered the entire reported range, b) reflected the scatter in the entire data set, and c) was spaced in temperature for convenient

graphical illustration with no loss in the detailed temperature dependence.

All of the data reported and modified in this way are given in Tables 6 through 19.

5. PHASE IV - DATA ANALYSIS AND RECOMMENDED VALUES

5.1 Thermal Conductivity

Figures 34 through 37 show the thermal conductivity data from Tables 6 through 19. It is clear that large variations in x exist throughout the

-52-
"ABLE 6. THERMOPHYSICAL PROPERTIES FOR AXM-5Q1 GRAPHITE AS REPORTED BY BRANDT (6).

THERMAL ELECTRICAL SPECIFIC THERMAL SEEBECK TEMPERATURE CONDUCTIVITY RESISTIVITY HEAT DENSITY DIFFUSIVITY COEFFICIENT

(K) (W-m-l-K-1) (yfi-m) (j.g-l.K-1) (kg-irr 3

) ( u m

2 -s-l) (uV-K-1)

SPEC. 42F, RESISTIVITY = 14.31, DENSITY = 1733

1110. 15.82

1202. 14.91

1333. 13.72

1450. 12.91

1560. 12.26

1669. 11.83

1783. 11.05

1910. 10.65

2045. 10.20

2163. 9.83

2275. 9.59

2315. 9.44

1333. 13.04

SPEC. 112C, RESISTIVITY = 14.88, DENSITY = 1723

1085. 17.08

1148. 16.51

1222. 15.64

1335. 14.59

1490. 13.55

1605. 12.91

1770. 11.89

1915. 11.52

2100. 10.73

2240. 10.08

TABLE 7. THERMOPHYSICAL PROPERTIES FOR AXM-5Q1 GRAPHITE AS REPORTED BY PARTICIPANT 1, SPEC. 62, ROOM TEMPERATURE ELECTRICAL RESISTIVITY = 12.40 uO'm, DENSITY

= 1757 kg-m-3

.

THERMAL ELECTRICAL SPECIFIC THERMAL SEEBECK TEMPERATURE CONDUCTIVITY RESISTIVITY HEAT DENSITY DIFFUSIVITY COEFFICIENT

(K) (W-m-i-K- 1

) (pcm) (J-g-^K" 1) (kg-nr 3

) (nm^s" 1) (yV-K" 1) 400.0 999.4

500.0 1207.3 600.0 1395.4

700.0 1533.4 800.0 1651.5 900.0 1739.7

1000. 1797.8

1200. 1824.4

-53-
TABLE 8. THERMOPHYSICAL PROPERTIES FOR AXM-5Q1 GRAPHITE AS REPORTED BY HUST (7).

THERMAL ELECTRICAL SPECIFIC THERMAL SEEBECK TEMPERATURE CONDUCTIVITY RESISTIVITY HEAT DENSITY DIFFUSIVITY COEFFICIENT

(K) (W-nri-K-l) (ufl-m) (J-g-l-K" 1

) (kg-nr 3) ( y m

2 -s-l) (jiV'K-1) SPEC. 310-0 296.0 .7280E+02 17.50 1693. SPEC. 310-1 296.8 .7300E+02 17.50 1689. SPEC. 310-2 296.7 .7370E+02 17.50 1690. SPEC. 310-3 296.9 •7380E+02 17.50 1698. SPEC. 310-4 296.4 .7440E+02 17.50 1702. SPEC. 520 296.7 .1057E+03 12.90 1731. SPEC. 400 296.3 .1219E+03 11.30 1755. SPEC. 410 296.6 .1180E+03 11.60 1736. SPEC. 102 296.4 .1126E+03 12.60 1755. SPEC. 401 296.2 .1025E+03 13.00 1716. SPEC. 100 297.0 .9700E+02 14.40 1755. SPEC. 311 296.5 •9510E+02 13.90 1722. SPEC. 312 296.9 .9250E+02 15.30 1757.

-54-
TABLE 9. THERMOPHYSICAL PROPERTIES FOR AXM-5Q1 GRAPHITE AS REPORTED BY HUST (7).

THERMAL ELECTRICAL SPECIFIC THERMAL SEEBECK TEMPERATURE CONDUCTIVITY RESISTIVITY HEAT DENSITY DIFFUSIVITY COEFFICIENT

(K) (W-m-l-K-1) (yfi-m) (j.g-l.K-1) (kg-m-3) ( y m2. s

- 1

) (pV-K-1)

SPEC. 013, RESISTIVITY = 12.58, DENSITY = 1728 6.000 .6332E-01 26.58 -3. 294 7.000 .9258E-01 26.54 -3.870 8.000 .1293E+00 26.49 -4.410 9.000 . 1743E+00 26.44 -4.932

10.00 •2284E+00 26.38 -5.418

12.00 .3687E+00 26.25 -6.300

14.00 .5521E+00 26.11 -7.092

16.00 .7845E+00 25.97 -7.758

18.00 .1062E+01 25.82 -8.334

20.00 .1403E+01 25.67 -8.802

25.00 .2465E+01 25.27 -9.594 30.00 .3847E+01 24.85 -9.918

35.00 .5560E+01 24.45 -9.918 40.00 .7553E+01 24.03 -9.684

45.00 •9827E+01 23.61 -9.306 50.00 •1232E+02 23.21 -8.856 60.00 .1793E+02 22.42 -7.812 70.00 .2414E+02 21.68 -6.732

80.00 .3065E+02 20.97 -5.688 90.00 .3735E+02 20.30 -4.716 100.0 .4416E+02 19.67 -3.816

120.0 •5727E+02 18.55 -2.214

140.0 .6927E+02 17.54 -.828

160.0 •7957E+02 16.65 .360

180.0 •8797E+02 15.86 1.386 200.0 .9456E+02 15.15 2.268

220.0 •9955E+02 14.51 3.006

240.0 .1030E+03 13.93 3.600

260.0 .1050E+03 13.41 4.050

280.0 .1070E+03 12.92 4.356

SPEC. 035, RESISTIVITY = 14.46, DENSITY = 1722 5.000 •3487E-01 28.77 -2.376 6.000 .5341E-01 28.74 -2.952

7.000 •7795E-01 28.69 -3.456 8.000 .1092E+00 28.64 -3.924

9.000 .1473E+00 28.59 -4.356 10.00 .1924E+00 28.53 -4.752

12.00 .3096E+00 28.41 -5.454

14.00 •4629E+00 28.28 -6.084

16.00 .6552E+00 28.13 -6.606

18.00 .8887E+00 27.99 -7.056 20.00 •1162E+01 27.83 -7.434

25.00 .2044E+01 27.44 -8.010

30.00 .3196E+01 27.04 -8.208

35.00 •4608E+01 26.64 -8.136 40.00 .6251E+01 26.23 -7.902

45.00 •8094E+01 25.84 -7.560

50.00 .1012E+02 25.45 -7.164

60.00 .1462E+02 24.68 -6.246 70.00 .1963E+02 23.95 -5. 292 80.00 •2494E+02 23.26 -4.356 90.00 •3034E+02 22.60 -3.456 100.0 .3595E+02 21.97 -2.628

120.0 •4686E+02 20.80 -1.134

140.0 .5686E+02 19.77 .180 160.0 .6546E+02 18.83 1.296

180.0 .7266E+02 18.00 2.304 200.0 •7845E+02 17.23 3.186 220.0 .8304E+02 16.54 3.960 240.0 .8643E+02 15.92 4.590

260.0 .8902E+02 15.36 5.112 280.0 .9051E+02 14.85 5.490 300.0 .9080E+02 14.38 5.742

-55-
TABLE 10. THERMOPHYSICAL PROPERTIES FOR AXM-5Q1 GRAPHITE AS REPORTED BY ISAACS (8), SPEC. 103-2, ROOM TEMPERATURE ELECTRICAL RESISTIVITY = 15.49 pfi-m, DENSITY

= 1721 kg-m' 3

.

THERMAL ELECTRICAL SPECIFIC THERMAL SEEBECK TEMPERATURE CONDUCTIVITY RESISTIVITY HEAT DENSITY DIFFUSIVITY COEFFICIENT

( K) (W-m-l-K-1) (ufi-m) (j.g-l.K-1) (kg-nr 3

) (pm2- s-l) (uV-K"!) 82.80 117. 89.96 156. 95.38 147. 111.2 180. 125.5 223. 142.7 265. 160.5 308. 181.9 423. 194.3 459. 215.7 573. 239.0 659. 260.8 760. 279.6 875. 289.4 955.

TABLE 11. THERMOPHYSICAL PROPERTIES FOR AXM-5Q1 GRAPHITE AS REPORTED BY MAGLIC (9), SPEC. 4, ROOM TEMPERATURE ELECTRICAL RESISTIVITY = 14.59 ufl-m, DENSITY

= 1755 kg-m" 3

.

THERMAL ELECTRICAL SPECIFIC THERMAL SEEBECK TEMPERATURE CONDUCTIVITY RESISTIVITY HEAT DENSITY DIFFUSIVITY COEFFICIENT

(K) (W-m-i-K-l) (pfi-m) (J-g-i-K" 1

) (kg-nr 3) (

|i m

2 -s- 1

) (yV-K" 1) 480.0 41.50

577.0 33.50 677.0 28.50 762.0 25.10 866.0 21.50 996.0 18.90

1112. 16.90

1224. 15.70

1339. 14.60

1458. 13.60

1558. 12.70

1647. 12.20

1713. 11.80

TABLE 12. THERMOPHYSICAL PROPERTIES FOR AXM-5Q1 GRAPHITE AS REPORTED BY MIRKOVICH (10), SPEC. 112B, ROOM TEMPERATURE ELECTRICAL RESISTIVITY = 15.00 vSl-m, DENSITY

= 1724 kg-m" 3

.

THERMAL ELECTRICAL SPECIFIC THERMAL SEEBECK TEMPERATURE CONDUCTIVITY RESISTIVITY HEAT DENSITY DIFFUSIVITY COEFFICIENT

(K) (W-m-i-K-l) (pfi-m) (J-g-l-K" 1

) (kg-m" 3

) ( y m

2 -s" 1

) (yV-K" 1

) 273.2 72.50

323.2 58.10

373.2 48.70 473.2 37.60

573.2 30.30

673.2 25.70 773.2 22.40 873.2 19.70 973.1 17.60

1073. 16.10 -56-
TABLE 13. THERMOPHYSICAL PROPERTIES FOR AXM-5Q1 GRAPHITE AS REPORTED BY MOORE (11), SPEC. 102, ROOM TEMPERATURE ELECTRICAL RESISTIVITY = 12.60 pfi-m, DENSITY

= 1770 kg-m" 3

.

THERMAL ELECTRICAL SPECIFIC THERMAL SEEBECK TEMPERATURE CONDUCTIVITY RESISTIVITY HEAT DENSITY DIFFUSIVITY COEFFICIENT

(j.g-l-K-1) (kg-m" 3

) (un^s" 1) (yV-K" 1

) -5.094 -3.564

-2.106 -.774

.414 1.458 2.340

3.078

3.762 4.122

4.446

4.644

4.716

4.698 4.572

4.356

4.050

1.782 -1.098 -3.654

-5.724

-6.372

( K) (W-m-l-K-1) 80.00 .2960E+02

100.0 .4300E+02

120.0 .5610E+02

140.0 .6800E+02

160.0 .7840E+02

180.0 .8710E+02

200.0 .9410E+02

220.0 .9950E+02

240.0 .1035E+03

260.0 .1062E+03

280.0 .1078E+03

300.0 .1084E+03 12.51 320.0 .1083E+03

340.0 •1082E+03

360.0 .1075E+03

380.0 •1065E+03

400.0 .1053E+03 10.92

500.0 .9830E+02 10.01 600.0 .8830E+02 9.36 700.0 .8010E+02 8.93 800.0 .7460E+02 8.66

900.0 .6820E+02 8.52 950.0 •6590E+02

TABLE 14. THERMOPHYSICAL PROPERTIES FOR AXM-5Q1 GRAPHITE AS REPORTED BY PARTICIPANT 5.

THERMAL ELECTRICAL SPECIFIC THERMAL SEEBECK TEMPERATURE CONDUCTIVITY RESISTIVITY HEAT DENSITY DIFFUSIVITY COEFFICIENT

( K) (W-m-i-K" 1

) (yfi-m) (J-g-^K" 1) (kg-m" 3

) (ym^s" 1

) (yV-K" 1

) SPEC. 006(CRA-1), RESISTIVITY = 14.20, DENSITY = 1696 363.2 .8732E+02

372.0 .8920E+02

538.7 .8070E+02

803.7 .6225E+02

1067. .5029E+02

SPEC. 32C(CRA-2), RESISTIVITY = 13.50, DENSITY = 1708 343.2 .9136E+02

508.7 .8387E+02 807.0 .6614E+02

1124. .5058E+02

SPEC. 32C(RIA-2A), RESISTIVITY = 13.91, DENSITY = 1717 1085. .5058E+02

1380. .4222E+02

1929. .3401E+02

2606. .2968E+02

SPEC. 006(RIA-1A), RESISTIVITY = 14.40, DENSITY = 1716

1077. .5361E+02

1115. .4799E+02

1366. .3920E+02

1524. .3876E+02

1877. .3285E+02

2001. .2853E+02

2613. .2853E+02

2615. .3041E+02

-57-
TABLE 15. THERMOPHYSICAL PROPERTIES FOR AXM-5Q1 GRAPHITE AS REPORTED BY PARTICIPANT 2, SPEC. 41B, ROOM TEMPERATURE ELECTRICAL RESISTIVITY = 18.81 pSTm, DENSITY

= 1706 kg-m" 3

.

THERMAL ELECTRICAL SPECIFIC THERMAL SEEBECK TEMPERATURE CONDUCTIVITY RESISTIVITY HEAT DENSITY DIFFUSIVITY COEFFICIENT

(K) (W-m-i-K-l) ( W £2-m) (J-g-l-K" 1

) (kg-m" 3) ( w m

2 -s-l) (uV-r 1

) 1350. 11.23 1933.

1400. 11.26 1947.

1500. 11.33 1969.

1600. 11.43 1990.

1700. 11.56 2008.

1800. 11.70 2022.

1900. 11.86 2039.

2000. 12.02 2053.

2100. 12.20 2066.

2200. 12.36 2076.

2300. 12.53 2086.

2400. 12.71 2096.

2500. 12.89 2104.

2600. 13.06 2112.

2700. 13.23 2120.

2800. 13.40 2122.

2900. 13.58 2130.

TABLE 16. THERMOPHYSICAL PROPERTIES FOR AXM-5Q1 GRAPHITE AS REPORTED BY P.'RTICIPANT 3, SPEC. 52, ROOM TEMPERATURE ELECTRICAL RESISTIVITY = 13.39 un*m, DENSITY

= 1738 kg-m" 3

.

THERMAL ELECTRICAL

TEMPERATURE CONDUCTIVITY RESISTIVITY

(K) (W-m-l-K-1) (yfi-m) 300.0 13.62

400.0 .9240E+02 12.14

500.0 .8770E+02 10.99 600.0 .8150E+02 10.25 700.0 .7580E+02 9.70 800.0 .7110E+02 9.36 900.0 .6690E+02 9.10

1000. .6230E+02 8.90

1100. .5800E+02 8.81

1200. .5390E+02 8.83

1300. •5030E+02 8.97

1400. 9.09

1500. 9.26

1600. 9.42

1700. 9.61

1800. 9.80

1900. 9.98

2000. 10.16

2100. 10.34

SPECIFIC THERMAL SEEBECK

HEAT DENSITY DIFFUSIVITY COEFFICIENT

(j.g-l.K-1) (kg-m" 3

) (pm2 -s-l) (yV-K" 1

)

-58-
TABLE 17. THERMOPHYSICAL PROPERTIES FOR AXM-5Q1 GRAPHITE AS REPORTED BY TAYLOR (12).

THERMAL ELECTRICAL SPECIFIC THERMAL SEEBECK TEMPERATURE CONDUCTIVITY RESISTIVITY HEAT DENSITY DIFFUSIVITY COEFFICIENT

(K) (W-m-l-K-1) (pfl-m) (j.g-l.K-1) (kg-m-3) ( P m

2 -s-l) (uV-K"l)

SPEC. 3A-1, RESISTIVITY = 13.80 DENSITY = 1744 400.0 •9720E+02 12.13 957. 1737. 58.50

500.0 .8920E+02 11.06 1168. 1734. 44.00

600.0 .8280E+02 10.36 1382. 1713. 34.60

700.0 .7730E+02 9.88 1520. 1727. 29.40 800.0 •7250E+02 9.50 1636. 1722. 25.70 900.0 .6730E+02 9.34 1726. 1718. 22.70

1000. .6280E+02 9.30 1797. 1714. 20.40

1100. .5860E+02 9.31 1859. 1709. 18.30

1200. .5470E+02 9.39 1905. 1705. 16.80

1300. .5120E+02 9.48 1942. 1700. 15.50

1400. .4820E+02 9.64 1975. 1696. 14.40

1500. .4560E+02 9.80 2002. 1692. 13.50

1600. .4360E+02 9.96 2028. 1687. 12.70

1700. .4210E+02 10.15 2050. 1682. 12.20

1800. .4080E+02 10.35 2070. 1677. 11.80

1900. .3980E+02 10.57 2087. 1673. 11.40

2000. .3880E+02 10.81 2100. 1668. 11.10

2100. .3800E+02 11.04 2111. 1663. 10.80

2200. .3740E+02 11.27 2127. 1658. 10.60

2300. .3700E+02 11.46 2140. 1653. 10.50

2400. .3650E+02 11.68 2155. 1647. 10.30

SPEC. 3A-2, RESISTIVITY = 13.00 DENSITY = 1789 400.0 .1022E+03 11.28 1781. 60.00

500.0 .9530E+02 10.24 1777. 45.90

600.0 •8870E+02 9.54 1774. 36.20

700.0 .8230E+02 9.06 1770. 30.60 800.0 .7680E+02 8.76 1766. 26.60 900.0 .7170E+02 8.59 1761. 23.60

1000. .6680E+02 8.54 1757. 21.20

1100. .6250E+02 8.52 1752. 19.20

1200. .5890E+02 8.57 1748. 17.70

1300. .5530E+02 8.67 1743. 16.30

1400. .5210E+02 8.78 1739. 15.20

1500. .4930E+02 8.94 1734. 14.20

1600. .4710E+02 9.10 1729. 13.40

1700. .4530E+02 9.26 1725. 12.80

1800. .4360E+02 9.45 1720. 12.20

1900. .4230E+02 9.65 1715. 11.80

2000. .4140E+02 9.85 1710. 11.50

2100. .4060E+02 10.06 1705. 11.30

2200. .4000E+02 10.29 1699. 11.10

2300. .3940E+02 10.53 1694. 10.90

2400. .3900E+02 10.77 1689. 10.70

SPEC. 001, RESISTIVITY = 14.40, DENSITY = 1698 300.0 .1005E+03 14.30 702. 1698. 84.30

400.0 .9350E+02 12.59 1695. 57.60

500.0 .8650E+02 11.48 1691. 43.70

600.0 .8040E+02 10.75 1688. 34.50

700.0 .7470E+02 10.31 1684. 29.20 800.0 .6980E+02 9.96 1680. 25.40

900.0 •6470E+02 9.76 1676. 22.40

1000. .6040E+02 9.70 1672. 20.10

1100. .5600E+02 9.71 1668. 18.10

1200. .5220E+02 9.87 1664. 16.50

1300. .4860E+02 10.13 1660. 15. 10 1400. .4570E+02 10.34 1655. 14.00

1500. .4330E+02 10.55 1650. 13.10

1600. .4110E+02 10.76 1646. 12.30

1700. .3960E+02 10.98 1641. 11.80

1800. .3820E+02 11.20 1636. 11.30

1900. .3700E+02 11.41 1631. 10.90

2000. .3610E+02 11.65 1626. 10.60

2100. .3540E+02 11.85 1621. 10.30

2200. •3480E+02 12.10 1616. 10.10

2300. .3430E+02 12.44 1611. 9.90

2400. .3400E+02 12.64 1606. 9.80

2500. .3350E+02 12.83 2168. 1601. 9.70 -59-
TABLE 18. THERMOPHYSICAL PROPERTIES FOR AXM-5Q1 GRAPHITE AS REPORTED BY TAYLOR (13).

THERMAL ELECTRICAL SPECIFIC THERMAL SEEBECK TEMPERATURE CONDUCTIVITY RESISTIVITY HEAT DENSITY DIFFUSIVITY COEFFICIENT

( K) (W-m-i-K- 1

) (jin-m) (J-g-^K" 1

) (kg-m" 3

) (yi^s" 1

) (yV-K"l)

SPEC. 102, RESISTIVITY = 13.12, DENSITY = 1751 530.0 .8350E+02 37.40 615.0 •7720E+02 31.30

733.0 .7130E+02 25.90 863.0 .6620E+02 22.30

989.0 .6100E+02 19.50

1113. .5740E+02 17.90

1315. .5130E+02 15.40

1423. .4860E+02 14.40

1575. .4490E+02 13.20

1717. .4320E+02 12.50

1890. .3840E+02 11.10

1982. .3900E+02 11.20

2155. .3760E+02 10.70

2318. .3450E+02 9.82

2410. .3470E+02 9.87

2503. .3100E+02 8.80

2615. .3290E+02 9.35

2705. •2920E+02 8.30

2810. .2920E+02 8.31

2933. .3040E+02 8.62

SPEC. 401, RESISTIVITY = 15.29, DENSITY = 1707 481.0 .8380E+02 41.30

596.0 .8090E+02 33.50

1220. .5430E+02 16.50

1392. .4900E+02 14.70

1504. .4610E+02 13.60

1615. .4400E+02 12.80

1788. .4230E+02 12.20

1839. .3850E+02 11.10

1992. .4140E+02 11.90

2094. .3900E+02 11.10

2186. .3720E+02 10.60

2247. .3740E+02 10.70

TABLE 19. THERMOPHYSICAL PROPERTIES FOR AXM-5Q1 GRAPHITE AS REPORTED BY PARTICIPANT 4, SPEC. 111-END 1, ROOM TEMPERATURE ELECTRICAL RESISTIVITY = 15.00 pfi'm, DENSITY

= 1666 kg-m-3.

THERMAL ELECTRICAL SPECIFIC THERMAL SEEBECK

TEMPERATURE CONDUCTIVITY RESISTIVITY HEAT DENSITY DIFFUSIVITY COEFFICIENT

( K) (W-m-i-K" 1

) (un-m) (J-g-i-K' 1

) (kg-m" 3) (pm^s" 1) (iiV-K" 1) 553.2 29.60 732.2 22.60 868.2 20.30

1049. 16.70

1225. 14.50

1421. 12.80

1598. 12.09

1824. 10.60

2020. 10.90

2220. 8.90

2460. 8.10

593.2 27.10 868.2 19.20

1005. 17.30

1188. 15.70

1343. 13.60

-60-
100

30 3 io

CD

ZD

CD

-ZL OCD

azI 0.3

zn

E-i

o.i

M l I I I

I 1 ' I

1

I I I I I I

I

0.03 LhJLd I I I I . 4 10 20 40

1

i

1 i1 1

' 1

i '

1 1 100 200 400 1000 2000 TEMPERRTURE,K

Figure 34. Thermal conductivity data from Hust (7) on seven AXM-5Q1 graphite

specimens at 296 K.

-61-
I ' I I I I

I —I—' I

' I

' I ' I I I I

I '

1

1 x

x

0.03 1 1 I i I I I I I i I i I i I i I i I I I I I i I i I i I i I i I I I I I i I 4 10 20 40 100 200 400 1000 2000 TEMPERRTURE,K

Figure 35. Thermal conductivity data from Hust (7) on seven AXM-5Q1 graphite

specimens, six at 296 K and one specimen from 6 to 300 K.

-62-
>-*

100 -Mi ii i| - i i

i < rwi mi - iJp&M''

: A O

30

7 A °

O

AO

O

+ i O

_ O

10 - O -

: o :

- o o - 3

: o - o o

1 : o

: o

" o - n i - o

o

o

-

0.1 o

: °

L O

0.03 i . i i i i l . i 4 10 20 40 100 200 400 1000 2000 temperrture:,k

Figure 36. Thermal conductivity data for seven AXM-5Q1 graphite specimens from

the following participants at temperatures from 5 to 2600 K: O- HUST(7) O- PARTICIPANT 5 A - MOORE ( 1 1 ) + - PARTICIPANT 5

- PARTICIPANT 5 X- PARTICIPANT 3 V- PARTICIPANT 5

-63-
100

30

M l I l I

| i

'

i

•

i

>

i i i i

|

i i i i I

£ 10

E

1 > 3 o

=)Q

£ 0.3

JO

o.i -

0.03 I I II I I i I i I i I I I I I i I i I i I 10 20 40 100 200 400 TEMPERRTURE,K

1000 2000

Figure 37. Thermal conductivity data for four AXM-5Q1 graphite specimens from

the following participants at temperatures from 300 to 2600 K: O- TAYLOR (12) A - TAYLOR ( 12)

- TAYLOR ( 12) V- TAYLOR ( 13)

-64-
temperature range as was the case at room temperature in Phase II. Numerous equations were tried to represent the general temperature dependence of these

thermal conductivity data. Because of the relatively large differences between

data sets, especially at high temperatures, an equation with a large number of coefficients was undesirable. The base equation finally selected to represent

the general behavior of these data is

G2 G4 G5

Xb

= G]J V(l + G3 T 4

) (5.1.1)

This equation was modified in two ways to obtain the best representation of the

data. First, the equation was modified according to the correlation between L and p described in Phase II which is equivalent to the multiplier M^. Second,

it was modified by a multiplier function, M2 to remove most of the remaining

oscillatory systematic deviations. The final representation of the thermal conductivity data is

X = X5 M

1 M2 (5.1.2) where

= (-18.51 + 0.01908 d Q

) x 10"6 /p o (5.1.3)

M2

= 1 + 0.0012 *n(T/5.4) an(T/15) *n(T/58) *n(T/180) *n(T/1000) *n(T/1700)

(5.1.4)

T = temperature in K, X is in W'm'^K, d0 is room temperature density in Kg/m3 and p0 is electrical resistivity in ft«m, and the parameters are

Sj = 0.000537 G

2

= 2.589 G3= 0.000202 G

4

= 1.678 G

5 = 2.02 Figures 38 through 41 show the deviations of the observed thermal conduc- tivity data from eq. (5.1.2). For convenience of comparison, Figures 42-44 contain all of the data on each plot. Figure 42 is a composite of Figures 38-41. Figure 43 shows the deviations of all the data from eq. (5.1.2) with M]_ = 1

-65-
30 |

i ii

i i i i |

i

i

i

i

i

i

i i

1

1 i i i

|

l

1

l

1

l

1 1 I I I

|

20 o 10

in

CDO

Q 10 O

-20

-30 l l I I I J i l i l i l 1 1 l l l I 10 20 40 100 200 400 TEMPERATURE,

1000 2000

Figure 38. Thermal conductivity deviations for seven AXM-5Q1 graphite specimens

as reported by Hust (7) from eq. (5.1.2) at 296 K.

-66-
o_Jccos

30 I i I

1 1 I I I

I i

I

i

I

i

I

i I1 1 I I I

I

20 -

10 -

CO

CDO 0

LJo

Q_

-10

-20

-30

m^nPTTT

xxXy v x xxxxx xxxxx xxxxxxx^l

I I I I I I I I 1 1 1 I I I I I I I I I I 1 1 1 I I I I 10 20 40 100 200 400 TEMPERATURE,

1000 2000

Figure 39. Thermal conductivity deviations for seven AXM-5Q1 graphite specimens

as reported by Hust (7) from eq. (5.1.2), six at 296 K and one at temperatures from 6 to 300 K.

-67-
o

_so

I CDm

o

>

Q

30

20

10

10

-20

-30

I

' I'

I l I I

|

oo^^ —D xxk

O -

' '

'

J-U. j-uJ. J-L i I 10 20 40 100 200 400 TEMPERRTURE,K

1000 2000

Figure 40. Thermal conductivity deviations for seven AXM-5Q1 graphite specimens

as reported by the following participants from eq. (5.1.2) at temperatures from 5 to 2600 K: O- HUST(7)

A - MOORE(ll)

- PARTICIPANT 5 V- PARTICIPANT 5

O- PARTICIPANT 5 + - PARTICIPANT 5 X- PARTICIPANT 3

-68-
o

i;T: o

1

30 i i

i

1 1 i i i

|

20

10

CO

CDO 0

6-«

10

-20

-30 L^Lxi

- i i > i i i i i

| I

' l'

l l l l

|

A A ^

1

I I 1 1 1 III

10 20 40 100 200 400 TEMPERATURE,

K

1000 2000

Figure 41. Thermal conductivity deviations for four AXM-5Q1 graphite specimens

as reported by the following participants from eq. (5.1.2) at temperatures from 300 to 2600 K: O- TAYLOR (12) A - TAYLOR ( 12)

- TRYLORt 12) V- TAYLOR (13)

-69-
30

20

CJ

eno

CO

CDO

>

a

o

CLIO -

-10 -

-20

•30

xx x x x xxxx xxxxx xxxxxxx^|

1 1

'

1 ' 1 1 1 1

1

1 '

v v : & n n°x<W^

• ° °Oooooo oO°0oOoo0o0 oOA

°«

A 2 £ . a /a^ +

: A AA v O 0 _ + !

+

10 20 40 100 200 400 TEMPERRTURE,K

1000 2000

Figure 42. Thermal conductivity deviations of all AXM-5Q1 graphite data from

eq. (5.1.2). Composite of Figures 38-41.

-70-
30

20

10 o

_]

azoi (A o CDO

Q

fr-«

-10

-20

-30

-40

I l l I

| l

1 l 1

l

1

l

1 1 l I I l ' l1

l

1

l

1 1 I I I

| x

o A A

A^ A A A A A

° UUU

°Oooooo oooooo 0oooo0 oO VL <> o o

I I 1 1

1

I I 1 1

1

I.I I 1 1

1

J 1 10 20 40 100 200 400 TEMPERRTURE,K

1000 2000

Figure 43. Thermal conductivity deviations of all AXMr5Ql graphite data from

eq. (5.1.2) with Mj = 1.

-71-
30

20

10

10

20 -

l I I l |

l ' l

1 l

' I '

I l I I

| I

' l

' I ' I

v

x x x^°\ XXX>< o^^L%^^A

CP ° o00^^®

°ooo° OoO «A' A A

A

+ -

30 1 1 n i i M I i iiit i-U-L i i i i 1 1 1 i nl

10 20 40 100 200 400 TEMPERATURE,

K

1000 2000

ure 44. Thermal conductivity deviations of all AXM-501 graphite Hata from

eq. (5.1.2) with M

2

= 1.

-72-
(i.e., no corrections for room temperature differences in density and electrical resistivity). Figure 44 shows the deviations of all data from eq. (5.1.2) with

M2

= 1 (i.e., no corrections for the residual oscillations). It is clear from these plots that the corrections for the room temperature characteristic differences are essential. However, relatively large scatter still exists at the higher temperatures. This scatter between data sets may be caused by a) experimental error and b) if the L vs d correlation found at room temperature is also a function of temperature. The data of Hust (7) on two specimens measured from 5 to 300 K suggests that the correlation is quite good to the lowest temperature

measured. The data of Taylor (12) on three specimens, and the data of participant 5 on four specimens suggest that the correlation is not as good at higher

temperatures.

Based on this research, it is concluded that this graphite can be a useful thermal conductivity standard with the following limitations:

a) Only those rods should be selected that show the smallest electrical resistivity vs position dependence.

b) The actual specimen used should be characterized for room temperature electrical resistivity and density values.

c) Specimens with room temperature electrical resistivities outside the range 13.0 to 15.0 ycrm and densities outside the range 1.70 to 1.75 g/cm3 should be excluded.

d) The uncertainty of eq. (5.1.2) at high temperatures is as high as

10%. Table 20 contains recommended values of X for temperatures from 5 to 2600 K as given by eq. (5.1.2) with p 0

= 14.5 yfi. m and d

0

= 1.73 g/cm3. it is noted that the correction for p0 and d

0 is zero at that point, i.e., = 1.

-73-
Table 20. Thermophysical properties of AXM-5Q1 graphite as calculated from the equations indicated in this report, for room temperature electrical resistivity = 14.5 yfi-m and density = 1730 kg/m3

.

THERMAL ELECTRICAL

MDtTDATIIDF HrtKtt 1 UKL rnNm itt t u t tv pf<;t<;ti\/tt Klj 1 o 1 1 V 1 1

\ M fU.m-1. K-l^ ^ n III l\ J (pfi*m)

c

0 .0354 28. 78

0 0537 28. 73

7 . 0783 28.67

o0 . 1099 28. 62

9 !l494 28*55

10 . 1971 28.48

15 . 573 28. 1

20 1. 201 27 . 71

25 2. 095 27. 28

30 3. 255 26.85

35 4. 675 26.43

40 6. 33 26. 00

45 8.23 25.59

50 10.32 25.19

55 12.59 24.79

60 15.03 24.41

65 17 . 59 24.04

70 20. 25 23.68

75 23.00 23.33

80 25.81 22*98

85 28.65 22.65

90 31.51 22. 33

95 34.37 22.02

i nn 37. 21 21.72

120 48. 16 20.60

140 57^9 19^60

160 66.4 18.71

180 73.

17. 92 200 78.9 17.20

220 83.

16. 55 240 86.4 15.97

260 88.8 15*44

280 90.4 14.96

300 91.3 14. 52 400 90.

12.83

500 84.

11.74

600 78.0 11.03

700 71.7 10. 58 800 fit; q dd. y 10. 30 900 60.

10. 15 1000 56.5 10.10

1100 52.7 10.12

AQ AQ in 1 q

1 300 46 . 68 1 0. 29 1400 A A 9Q 41 . CO in /n

1500 42. 22 10. 58 1DUU /in /ic in 7 a 1U. / 0 1700 38. 95 10. 94 1800 37 '.67 11*14

1900 36.58 11.34

2000 35.66 11.55

2100 34.89 11.75

2200 34.25 11.96

2300 33.72 12.17

2400 33.29 12.38

2500 32.96 12.59

SPECIFIC THERMAL THERMAL

HEAT DIFFUSIVITY EXPANSION

(J.kg-1-K-1) (pm2. S -l)

(%)

- .198

- .197

- .196

- .196

- .195

- .194

- .191

- .188

- .184

- .181

- .178

- .174

- .171

- .168

- .164

- .161

- .158

- .154

- .151

- .148

- .144

- .141

- .137

- .134

- .120

- .107

- .093

- .079

- .065

- .051

- .037

- .023

- .009

.005 995 52.52 .078

1208 40.67 .152

1381 32.90 .228

1518 27.54 .306

1629 23.67 .386

1718 20.78 .468 1790 18.55 .551 1849 16.80 .636

1898 15.39 .723 1939 14.26 .811 1973 13.32 .901 2002 12.56 .993 2027 11.92 1.08 2048 11.39 1.18 2066 10.95 1.27 2082 10.58 1.37 1096 10.28 1.47 2108 10.03 1.57 2118 9.82 1.67 2128 9.66 1.78 2136 9.53 1.88 2143 9.43 1.99

-74-
The uncertainty of the A values in Table 20 is estimated to be +2% at temperatures below 300 K. At higher temperatures, the uncertainty increases to +10% at 2600 K. 5.2 Electrical Resistivity

Figures 45 through 47 show the electrical resistivity data from Tables 6 through 19. Based upon the abnormal behavior of the electrical resistivity data from Table 15, i.e., the results reported by participant 2, (see Figure 47) this

data set was excluded from the following comparisons. It is noted that this specimen had an abnormally high room temperature electrical resistivity and is the basis for the previous restriction on the range of valid thermal conduc- tivities. Again, an equation with relatively few coefficients was desired to represent the general temperature behavior of the data. The equation selected

is

p = G rG

2 Exp(-(jin(T/G3)/G4 ) 2

) (5.2.1)

This equation was modified to account for the room temperature differences, and the resulting final equations is

p = G rG2 Exp(-(iin(T/G3)/G4) 2

) + p0 -14.5 (5.2.2)

where p = electrical resistivity in yft*m, at temperature, T, in K and p0

= the room temperature resistivity of the specimen in yft*m. The least squares values of the coefficients are Gj = 28.9, G2

= 18.8, G3

= 1023, and G 4= 2.37. Although some systematic differences are apparent in the following deviation

plots, no further modification seemed justified because of the larger scatter

between data sets.

-75-
30 I i mi i i i

| l

'

I 'I

'

I I I I |

27.5

25

•v 22.5

E—

GO

CO

LJ

Cd

_Ja:ot—

a:o

LJ

20 -

17.5

15

LJ 12.5

10

7.5

10

i i i i i 1 1 i i i I i i i i i 1 1 i i i I 20 40 100 200 400 TEMPERATURE,

1000 2000

Figure 45. Electrical resistivity data from Hust (7) on seven AXM-501 graphite

specimens at 296 K.

-76-
40 100 200 400 TEMPERRTURE,K

1000 2000

Figure 46. Electrical resistivity data from Hust (7) on seven AXM-5Q1 graphite

specimens, six at 296 K and one specimen from 6 to 300 K.

-77-
30 i i

i

1

1 i i i |

i

i

i

i ii

i

i

1

1 i i i | ii i

i ii

i ii

i i i i | i

i

7.5 I i l 1 1 l l l I i I i l i l i l i l l l I I i l i I i l i I 1 1 l I I I i l 4 10 20 40 100 200 400 1000 2000 TEMPERATURE,

K

Figure 47. Electrical resistivity data for seven AXM-5Q1 graphite specimens from

the following participants from 5 to 2900 K: O- MUST (7) O - TAYL0RU2)

A - MOORE (11) + - TAYLOR ( 12) - PARTICIPANT 2 X- TAYLOR (12) V- PARTICIPANT 3

-78-
Figures 48 through 50 show the deviations of the experimental data from

eq. (5.2.2). For convenience of comparison, these data are all shown on a single

graph in Figure 51. Figure 52 shows the deviations of the data from eq. (5.2.1) which is uncorrected for room temperature differences. It is clear that most of the differences at high and low temperatures are accounted for simply by the room temperature differences.

A comment about the data of participant 2 (the data set excluded earlier) is in order. It appears that for an unknown reason the value of p 0 is incorrect

for this specimen. The actual specimen used was in the form of a thin hollow

cylinder. The rod from which it was machined was measured at NBS and by the participant. These p 0 values agreed to within 2%. The participant also measured the p 0 of the hollow cylinder and obtained a value only slightly

higher. However, the deviations of the data from participant 2 from eq. (5.2.2) are near -30% at all temperatures. This difference can be nearly eliminated if a value of 15.2 yft*m is used for p 0 instead of 18.81 yn«m. Using a value of 15.2 yft-m yields deviations of 1.5% at 1350 K, and -4.0% at 2900 K, varying

smoothly and nearly linearly at temperatures between these extremes.

Based on this research, it is concluded that this graphite can be a useful electrical resistivity standard with the same limitations given in the previous

section. Table 20 contains recommended values of electrical resistivity for tempera- tures from 5 to 2500 K as given by eq. (5.2.2) with p 0

= 14.5 yft*m. 5.3 Specific Heat Figure 53 shows the specific heat data from Tables 6 through 19. The high temperature data of participants 1 and 2 and Taylor (12) are in reasonable agreement. However, the low temperature data of Isaacs is not only

-79-
m i i i i |

'—i— i i p i I i i

|

1—i ' i i i i i i i | —

8

III I I I I i I i I i I i I i I I I I I i I i I i I i I i I I I I I i I 4 10 20 40 100 200 400 1000 2000 TEMPERRTURE,K

Figure 48. Electrical resistivity deviations for seven AXM-5Q1 graphite

specimens as reported by Hust (7) from eq. (5.2.2) at 296 K.

-80-

o

_j

eno

i CO

CDo

Q

O

Q_
4 l"^PrT^n^T"T TM^~^,TMTTM^TMT^T^n^ M l I I I

|

CJ ^ _J

azoi CO

QQO 0 a

xxxxxxx

xxx

x x xxxx Xx . * x xxx

CD *

III I I I I I

1

I

1 I 111 I I I I I I I 1 1 1 1 I I I I I 10 20 40 100 200 TEMPERATURE,

K

400 1000 2000

"l^jre 49. Electrical resistivity deviations for seven AXM-5Q1 graphite specimens as reported by Hust (7) from eq. (5.2.2), six at 296 K and one

at temperatures from 6 to 300 K.

-81-
o

-J

eno

i en

CDo

O

Q_

2 -

-4

M l I ll| I ' I ' I

'

I

' I HTH I I I

| A An

ooo0

oOOOo 0

++

o o ooooooo

oo

+

+

-fa o 8

+

+

+ + ^<*><> o

III Mil I I I I 1 1 1 I I I I 10 20 40 100 200 TEMPERRTURE,K

400 1000 2000

Figure 50. Electrical resistivity deviations for six AXM-5Q1 graphite specimens

as reported by the following participants from eq. (5.2.2) at temperatures from 5 to 2500 K. O- HUST(7)

A- MOORE (11) - PARTICIPANT 3 V - TAYLOR (12) O - TAYLOR (12) + -TAYL0RU2)

-82-
2

-

CO

CDO 0

1 1 1 1 1 1 1 ' 1 ' 1

• 1' 1 1 1 1 1

1 '1

0 ooO°

00000 °oQ

, n oo°° O

0 ooooo°° o

o

I

' 1 1 1 1 1

1 ' 1 ad

A ° J-

++

+

vX x xxxxx x x % . x xxxx xxxxx xxx XXxxXxJ

O ° a.

'

100 200 400 TEMPERRTURE,K

1000 2000

Figure 51. Electrical resistivity deviations of all (excluding participant 2) AXM-5Q1 graphite data from eq. (5.2.2). Composite of Figures 48-50.

-83-
20

10 o

_Jeno nu

i COCDO -10

CxJ Q -20 I- E-O

Q_ -30

40

I ' I l l I

|

i ' I

'

l

'

I

' I I I I

0 OOOOO OOOOO O QQOOO Q O OOQ O 0 OOOQQ^

~ _

+++++ xxxxx XXXXX X xxxxx Xxxxx D DgV

X><XXvx 9 O x*. o o

III I I I I I I 1 1

I I I I I I I I I I I I I 10 20 40 100 200 400 TEMPERATURE,

1000 2000

Figure 52. Electrical resistivity deviations of all AXM-5Q1 graphite data from

eq. (5.2.2) without the correction for room temperature differences.

-84-
2000

l 'l'M| 'I ' I

'

I

'

I

'

|

1000

E-h GCLJ

600

400 O

LJ

Q_

CO

200 -

100 60

I 100 200 400 600 TEMPERRTURE,K

1000 2000

Figure 53. Specific heat data for four AXM-5Q1 graphite specimens from the following participants at temperatures from 80 to 2900 K: O- PARTICIPANT 1 A - ISAACS(8)

- PARTICIPANT 2 V- TAYLOR (12)

=85<
abnormal for expected specific heat behavior, but also clearly discordant with the other three data sets. With this in mind and the recognition that the lowest temperature values may be in error, Isaacs data were given a low weight in fitting an equation to the entire data base. The equation selected for this purpose

is

C = ( Gl TG

2 G/V1 (5.3.1)

where C is in J • kg" 1

• K" 1

, T is in K and the parameters obtained are

G

1 = 11.07 G2

= 1.644 G

3

= 0.0003688 G

4

= 0.02191

The deviations of the data from eq. (5.3.1) are shown in Figure 54. Because of the limited specific heat data and the discordance between data

sets, recommended values are not given at this time. Research on specific heat of graphite is continuing. Table 20 lists values of specific heat as calculated

from eq. (5.3.1)

5.4 Thermal Diffusivity

Figures 55 and 56 show the thermal diffusivity data from Tables 6 through

19. Equation (5.4.1), the definition of diffusivity, was selected to represent

the temperature dependence of these data.

D = A/Cd (5.4.1)

where x is given by eq. (5.2.1), C is given by eq. (5.3.1) and d = d0 /(l + AL/L) 3

. Figures 57 and 58 show the deviation of the experimental data from

eq. (5.4.1). Figures 59 and 60 show the deviations without the corrections for room temperature differences.

-86-
30

25 d 20 - ? 15

en" CD0 10 1

5 d ° Q_ -5

-10

1 I' l 'i Ii i i i

|

i i ' '

I

1 1 1

1

1 1 1 1 1

1

I |I

|

i

|

i

| A

A

_Q Q g 9 9 9oV7vvvyWW^

A A

Pxtnniiiiini 1

.LuUl hull i I i I i I i I 60 100 200 400 600 1000 2000 TEMPERATURE,

Figure 54. Specific heat deviations for four AXM-5Q1 graphite specimens as reported by the following patici pants from eq. (5.3.1) at temperatures from 80 to 2900 K: O- PARTICIPANT 1 A - ISAACS (8) - PARTICIPANT 2 V- TAYLOR (12)

-87-
60

40

>i—

CO

LiCC

20 -

10

I ' I ' I

' I

v ft V

200

+

D

t

v * +

i I i 400 600 1000 TEMPERATURE,

2000

Figure 55. Thermal diffusivity data for seven AXM-5Q1 graphite specimens from

the following participants from 280 to 2600 K: O- BRANDT (6) A - BRANDT (6) - MAGLICO)

V- MIRKOVICH(IO)

O- TAYLOR (12) + - TAYLOR (12) X- TAYLOR (12)
CO

ZD

az

2=LJ

200 400 600 1000 2000 TEMPERATURE,

K

Figure 56. Thermal diffusivity data for four AXM-5Q1 graphite specimens from the following participants from 480 to 2900 K: O- TAYLOR! 13) A - TAYLOR ( 13) - PARTICIPANT 4 V- PARTICIPANT 4

-89-
20

10 -

r-r i

1

1

1

1—r i-nr

X X X Xx_ A A A

0 n

~ v ^g>^^-v^ - + a + / v v * o

°

+ ++ + +++q<*»

-10 -

-20 -

-30 -

-40

200 400 600 1000 TEMPERRTURE,K

2000

Figure 57. Thermal diffusi vity deviations for seven AXM-5Q1 graphite specimens

as reported by the following participants from eq. (5.4.1) at temperatures from 280 to 2600 K: O- BRANDT (6) A - BRANDT (6) - MAGLICO)

V- MIRKOVICH(IO)

O- TAYLOR (12) + - TAYLOR (12) X- TAYLOR (12)

-90-
20

10

CO

CDO -10

-20

-30

-4P

1-1 1—i—1—1 A

1 1 1 i

V A

' A

7 o °°°° o 0

D

: o O £ O o o

D '

0 o

o [ o "i CP

• • • • - • ' • '

• 200 400 600 1000 TEMPERRTURE,K

2000

Figure 58. Thermal diffusivity deviations for four AXM-5Q1 graphite specimens as from the following participants from eq. (5.4.1) at temperatures from 480 to 2900 K: O- TAYLOR (13) A - TAYLOR (13) - PARTICIPANT 4 V- PARTICIPANT 4

-91-
>

LJCD

1-h

20

10 - O

_J

O U

I CO

CDO -10

-20

-30

•40200

+

+ +

+

o

o X o X oX

Xn

I

1

I ' I

1

1 + + + + + ++ + +++++++++

o o ° o o o 0 x x x x

"

. a A ^X x Q, A

400 600 1000 TEMPERRTURE,K

*<6

2000

Figure 59. Thermal diffusivity deviations for seven AXM-501 graphite specimens

as from the following participants from eq. (5.4.1) (without

corrections for room temperature differences) at temperatures from

280 to 2600 K: O- BRANDT (6) A - BRANDT (6) - MAGLICO)

V- MRKOVICH(IO)

O- TAYLOR (12) + - TAYLOR (12) X- TAYLOR (12)

-92-
20

10

CC n O U

I CO

CDO -10 >

LJQ

E—O

Q_

-20 -

-30

-40.

o

A

n O O ° *«*.**. : —© A O

V

V

V D

O i1 7° CP"

U i i i 1 . . .' 200 400 600 1000 TEMPERATURE,

K

2000

Figure 60. Thermal diffusivity deviations for four AXM-5Q1 graphite specimens as from the following participants from eg. (5.4.1) (without corrections

for room temperature differences) at temperatures from 480 to

2900 K: O- TAYLOR (13) A - TAYLOR (13)

- PARTICIPANT 4 V- PARTICIPANT 4

-93-
These deviation plots indicate, first, that an independent equation for dif- fusivity is not necessary at this time and, second, that the deviations between

the participants are about that expected from previously reported experimental

uncertainties of such measurements. In addition, the difference in the spread of data is not reduced appreciably through the application of the room temperature

correlation. The reason for this is not clear but the following should be noted:

a) thermal diffusivity data from other studies are typically spread by about +10%

and b) thermal diffusivity specimens are frequently very small, making accurate

electrical resistivity characterization difficult. The latter point should not contribute significantly however, because the bulk specimens were characterized

and highly localized inhomogeneities should not be this large. It is concluded therefore that most of this spread is caused by experimental variability. The excellent agreement of eq. (5.4.1) with the mean of all the data is very encouraging.

A recommendation for use of this graphite as a thermal diffusivity standard

will be given further consideration. Table 20 lists values of thermal diffu- sivity as calculated from eq. (5.4.1) with p 0

= 14.5 pfi'm and d0= 1730 Kg/m3 from 400 to 2500 K. 5.5 Thermal Expansion

No thermal expansion data per se were reported in this study. However, the density data reported by Taylor (12) were actually obtained from thermal expansion measurements. These data were analyzed by comparing them to

d = d

0 /(l + aL/L)3 (5.5.1)

where aL/L values were computed from the equation

AL/L = -0.201 + 6.595 x 1Q~4T + 9.593 x 10"8T

2 -3.427 x 10" 12T

3 (5.5.2)

-94-
Eq. (5.5.2) was obtained from Touloukian, et al . (14). The density deviations obtained are illustrated in Figure 61. It is noted that excellent agreement is obtained. The fact that the deviations for each specimen are nearly parallel to the zero line indicate that the thermal expansion data of Taylor (12) are in good

agreement with eq. (5.5.2). Values of thermal expansion as calculated from

eq. (5.5.2) are listed in Table 20. 5.6 Seebeck Coefficient Figure 62 shows the Seebeck coefficient data from Tables 6 through 19. No representation of these data was undertaken. Until an interest is expressed in this property as an SRM, no further work is planned.

6. ACKNOWLEDGMENTS

I acknowledge the assistance, suggestions, and encouragement of several as- sociates involved in this program. In particular, I thank Greg Ruff, Susan

Fiske, Kevin Kayse, and Bruce Howrey of this laboratory for the numerous measurements and data analysis they have performed. My appreciation is given to Peyton Moore and his associates at ORNL for advice and assistance on the construction of the ambient-temperature comparative thermal conductivity apparatus. The con- tinued support, encouragement, and suggestions of M. Minges (AFML) and R. E. Michael is and R. K. Kirby (NBS, OSRM) is also acknowledged. The interest and co- operation of Wayne Fagen of P0C0 Graphite, Inc. has helped to assure the success

of this program. The efforts of each of the cooperative participants of the measurement program are acknowledged. Without their participation this work could not have been completed. My appreciation is also expressed to Carole Montgomery, who typed the manuscript and assisted in the layout of the figures

and tables.

-95-
0.2 — 0.1

• o

_J

azo

o.o

CO

CDO

£3 -o-i

O

0- -0.2

-0.3

200

I

' i i i

|

I i i i i I

I ' I

' I ' I

A a A A

A A

X X

'AAA

x *xxxx

x x

x xxx x v oS o0o xj o o o

I.I.I

400 600 1000 TEMPERATURE,

K

2000

Figure 61. Density deviations for three AXM-5Q1 specimens as reported by

Taylor (12) from eq. (5.5.1) for temperatures from 300 to 2500 K,

-96-
7.5 p-m i i i |

i i i i

' i i i i i i

1

i

1

i

1

i * i i i

2.5 AO

AO

AO

o

-2.5

-7.5

10 -

A

OA

O A

3 8

O A

A o OA A

O O

12.5 l i l i I i I i I

i .i.i.i ii

10 20 40 100 200 TEMPERATURE,

K

400

Figure 62. Seebeck coefficient <teta for three AXM-5Q1 graphite specimens. Two data sets from Hust (7) at temperatures from 5 to 300 K and one set from Moore (11) at temperatures from 80 to 800 K.

-97-
7. REFERENCES

1. E. Fitzer, Thermophysical Properties of Solid Materials, Advisory Report 12 (1967); Advisory Report 38 (1972); Report 606 (1972), AGARD, NATO, France.

2. M. L. Minges, Evaluation of Selected Refractories as High-Temperature Ther- mophysical Property Calibration Materials, AFML Technical Report TR-73-278

(1974); Int. J. Heat and Mass Transfer, Vol. 17, 1365-1382 (1974).

3. D. L. McElroy, W. M. Ewing, T. G. Kollie, R. S. Graves, and R. M. Steele,

Room Temperature Measurements of Electrical Resistivity and Thermal Conduc- tivity of Various Graphites, 0RNL-TM-3477 (1971).

4. K. E. Wilkes, Technical Studies for the NERVA Radiation Effects Program -- Annealing Effects of Temperature on Radiation -- Induced Changes in the

Thermal Conductivity of Graphite Materials, Summary Report BMI-NRE-20

(1972).

5. M. L. Minges, The Standard Reference Materials and Data Programs of the CODATA Task Group on Thermophysical Properties, in Proceedings of the 17th International Thermal Conductivity Conference, ed. J. G. Hust, Plenum Press, New York (1983).

6. R. Brandt and G. Neuer, Thermal Diffusivity Measurements on Reference Mate- rials at IKE, in Proceedings of the 17th International Thermal Conductivity

Conference, ed. J. G. Hust, Plenum Press, New York (1983).

7. J. G. Hust, unpublished report.

8. L. L. Isaacs and W. Y. Wang, Thermal Properties of POCO-Process Graphite, in Proceedings of the 17th International Thermal Conductivity Conference, ed. J. G. Hust, Plenum Press, New York (1983).

9. K. Maglic, N. Perovic, and Z. Zivotic, Thermal Diffusivity of Candidate

Standard Reference Materials, in Proceedings of the 17th International

Thermal Conductivity Conference, ed. J. G. Hust, Plenum Press, New York (1983).

10. V. V. Mirkovich, Thermal Diffusivity of a P0C0 Graphite, in Proceedings of the 17th International Thermal Conductivity Conference, ed. J. G. Hust, Plenum Press, New York (1983).

11. J. P. Moore and R. S. Graves, The Thermal Transport Properties of a P0C0 AXM-5Q1 Graphite from 80 to 970 K, in Proceedings of the 17th International

Thermal Conductivity Conference, ed. J. G. Hust, Plenum Press, New York (1983).

12. R. E. Taylor and H. Groot, Thermophysical Properties of P0C0 Graphite, High

Temperatures— High Pressures, Vol. 12, 147-160 (1980).

13. R. Taylor, Thermal Diffusivity of P0C0 Graphite and Stainless Steel SRM 735-S in Proceedings of the 17th International Thermal Conductivity

Conference, ed. J. G. Hust, Plenum Press, New York (1983).

-98-
14. Y. S. Touloukian, R. k. Kirby, R. e. Taylor and T v d , Thermophysical Properties of Matter Vol U rt

Y,', R' Lee > Solids, p. 75, Plenum Press, New York (977)'

Expansion, Nonmetallic

-99-
NBS-114A (REV. 2-8C)

1. PUBLICATION OR 2. Performing Organ. Report No. 3. Publication Date

' REPORT NO. BIBLIOGRAPHIC DATA

SHEET (See instructions) NBS/SP-260/89 September 1984

4. title and subtitle standard Reference Materials:

A Fine-Grained, Isotropic Graphite for Use as NBS Thermophysical Property RM's From

5 to 2500 K

5. AUTHOR(S) Jerome G. Hust

6. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions) 7. Contract/Grant No. NATIONAL BUREAU OF STANDARDS DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered BOULDER, CO 80303

Final

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State, ZIP) Office of Standard Reference Materials

National Measurement Laboratory

National Bureau of Standards Gaithersburg, MP 20899

10. SUPPLEMENTARY NOTES Library of Congress Catalog Card Number: 84-601106

Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant bibliography or literature survey, mention it here) The Chemical Engineering Science Division (Boulder, Colorado) in conjunction with the Office of Standard Reference Materials (Gaithersburg, Maryland) of the National Bureau of Standards, and the C0DATA Task Group on Thermal Transport Properties have in- vestigated graphite as a potential, extended temperature range, Research Material (RM). A large number of isotropic, fine-grained graphite rods in various diameters were ob- tained for these investigations.

In Phase I, electrical resistivity and density measurements were performed on nu- merous rods at temperatures from 4 to 300 K. In Phase II, thermal conductivity mea- surements were performed on thirteen specimens at about 20 °C. These measurements show

that transport property variations, both between and within these rods, is relatively

large (approximately 10%). However, a correlation between these variables is shown to exist which will allow the calculation of thermal conductivity from simple and inexpensive electrical resistivity and density measurements to within about +2%. In Phase III, a large number of specimens were characterized for room temperature electrical resistivity and density. These measurements were in preparation for the worldwide distribution of specimens to participants that agreed to make thermal and electrical property measurements. Phase IV describes the results of the measurements from the various participants. Phase V describes the analysis of these data.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons) characterization; density; electrical resistivity; graphite, Lorenz ratio; Research

Materials; thermal conductivity.

13. AVAILABILITY

PCI Unlimited

|

| For Official Distribution. Do Not Release to NTIS

[A] Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

f"J Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

116

.S. GOVERNMENT PRINTING OFFICE : 1984 0-420-997/10039
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area. Often serve as a vehicle for final reports of work performed at NBS under the sponsorship of other government agencies. Voluntary Product Standards—Developed under procedures published by the Department of Commerce in Part 10, Title 15, of the Code of Federal Regulations. The standards establish nationally recognized re- quirements for products, and provide all concerned interests with a basis for common understanding of the

characteristics of the products. NBS administers this program as a supplement to the activities of the private sector standardizing organizations. Consumer Information Series—Practical information, based on NBS research and experience, covering areas of interest to the consumer. Easily understandable language and illustrations provide useful background

knowledge for shopping in today's technological marketplace. Order the above NBS publications from: Superintendent of Documents, Government Printing Office, Washington, DC 20402. Order the following NBS publications—FIPS and NBSIR 's—from the National Technical Information Service, Springfield, VA 22161. Federal Information Processing Standards Publications (FIPS PUB)—Publications in this series collectively constitute the Federal Information Processing Standards Register. The Register serves as the official source of

information in the Federal Government regarding standards issued by NBS pursuant to the Federal Property and Administrative Services Act of 1949 as amended, Public Law 89-306 (79 Stat. 1127), and as implemented by Executive Order 11717 (38 FR 12315, dated May 11, 1973) and Part 6 of Title 15 CFR (Code of Federal

Regulations). NBS Interagency Reports (NBSIR)—A special series of interim or final reports on work performed by NBS

for outside sponsors (both government and non-government). In general, initial distribution is handled by the sponsor; public distribution is by the National Technical Information Service, Springfield, VA 22161, in paper copy or microfiche form.
U.S. Department of Commerce

National Bureau of Standards

Gaithersburg, MD 20899

Official Business

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