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Graphite: A Future Structural Material

Published online by Cambridge University Press:  07 June 2016

A. J. Kennedy*
Affiliation:
The College of Aeronautics, Cranfield
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Summary

Graphite is a material with unique high-temperature properties. Its strength and modulus increase with temperature up to about 2000-2500°C., in which range it exhibits a higher strength than any known material. The development of new types of graphite (such as pyrolytic graphite, deposited from the vapour) and impregnated graphites, are both significant to future technology. The highly-oriented pyrolytic graphites in particular, with their marked thermal and mechanical anisotropy, and their superior mechanical properties (60 x 103 lb./in.2 strength at 2750°C, with 60 per cent ductility) offer distinct possibilities, particularly in composite structures. Graphite sublimes directly from the solid to vapour phase at 3700°C. at atmospheric pressure. As the sublimation energy is high, it is, at least in theory, a very efficient ablating material. It also has a high creep resistance. Surface reactions limit its value, particularly in oxidising environments, and coatings, or other methods of surface protection, are of high importance. The modulus of graphite is low, being about one-half of that for lead at room temperature, increasing with temperature to a maximum in the region of 2200°C. The properties vary in detail from one type of graphite to another, and with the direction in which measurements are made. Graphite has a low density (about 2·0) and is comparatively cheap, so that its low temperature limitations (zero ductility at room temperature) may be offset, at least in part, by a re-appraisal of the design factors. It can be joined and fabricated fairly readily, and appears to be a material of great value to advanced high-temperature projects in the future, where composite assemblies of various kinds will be essential.

Type
Research Article
Copyright
Copyright © Royal Aeronautical Society. 1960

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References

1. Murphy, A. J. and Kennedy, A. J. Temperature Effects on Material Characteristics. Fourth AGARD Combustion and Propulsion Colloquium, Milan, 1960. Pergamon Press, London.Google Scholar
2. Kennedy, A. J. Dislocations and Twinning in Graphite. Proceedings of the Physical Society, 75, 607, 1960.Google Scholar
3. Tsuzuku, T. Dislocations in Graphite Crystals. Proceedings of the Third International Conference on Carbon, Buffalo, 1957. Pergamon Press, London, 1959.Google Scholar
4. Bowman, J. C. Imperfections in the Graphite Structure. Proceedings of the First and Second International Conferences on Carbon, Buffalo. University of Buffalo, 1956.Google Scholar
5. Bradshaw, F. J. and Wheeler, C. Some Interesting Properties of Pyrolytic Carbon: Deformation of Deposited Carbon. Journal of Less Common Metals, Vol. 1, p. 101, 1959.Google Scholar
6. Brown, A. R. G., Clark, D., and Easterbrook, J. Some Interesting Properties of Pyrolytic Carbon: Structure and Density. Journal of Less Common Metals, Vol. 1, p. 94, 1959.Google Scholar
7. Keon, E. F. The Preparation and Properties of Pyrolytic Graphite. Paper No. 74. Proceedings of the Fourth International Conference on Carbon, Buffalo, 1959.Google Scholar
8. Boyland, D. A. The Reduction of the Permeability of Graphite. G.E.C. Atomic Energy Review, Vol. 2, March 1959.Google Scholar
9. Watt, W., Bickerdike, R. L., Brown, A. R. G., Johnson, W., and Hughes, G. Production of Impermeable Graphite. Nuclear Power, February, 1959.Google Scholar
10. Allen, J. M., and Harp, J. L. Development of Testing Properties Procedures and Evaluation of Refractory Materials. Wright Air Development Center Technical Report No. 58-682, 1959.Google Scholar
11. Janes, M. Graphite-based Materials for High Temperature Applications. Wright Air Development Center Technical Report No. 57-602, 1958.Google Scholar
12. Nudelman, H. B. Zirconium and Boron Carbide Coatings for Graphite. WAL 37T48, Watertown Arsenal Laboratories, U.S.A., June 1957.Google Scholar
13. Adams, R. E., and Nelson, H. R. Tensile and Creep Properties of Graphite. Battelle Memorial Institute Report No. BMJ-N-45, May 1950.Google Scholar
14. Binning, M. S. and Billing, B. F. The Mechanical Properties in Tension and Compression at Room Temperature and 1000°C. of Three Moulded Carbon Materials. R.A.E. Technical Note Met. 271, 1957.Google Scholar
15. Davidson, H. W., and Losty, H. H. W. Elastic and Plastic Properties of Carbon and Graphite. Mechanical Properties of Non-Metallic Brittle Materials, p. 219. Butterworths Scientific Publications, 1959.Google Scholar
16. Green, L. JR High-Temperature Compression Testing of Graphite. Journal of Applied Mechanics, Vol. 20, p . 289, 1953.CrossRefGoogle Scholar
17. Malstrom, C, Keen, R., and Green, L. JR., Some Mechanical Properties of Graphite at Elevated Temperatures. Journal of Applied Physics, Vol. 22, p. 593, 1951.CrossRefGoogle Scholar
18. Martens, H. E., Jaffe, L. D., and Jepson, J. E. High Temperature Tensile Properties of Graphites. California Institute of Technology Jet Propulsion Laboratory Report No. 20-326, 1957.Google Scholar
19. Mrozowski, S. Mechanical Strength, Thermal Expansion and Structure of Cokes and Carbons. Proceedings of the First and Second International Conferences on Carbon. University of Buffalo, 1956.Google Scholar
20. Martens, H. E., Jaffe, L. D., and Button, D. D. High-Temperature Short-Time Creep of Graphite. California Institute of Technology Jet Propulsion Laboratory Report No. 20-373, 1958.Google Scholar
21. Aves, R., Baines, D., Jaques, T. A. J., and Wade, F. High Temperature Graphite Joints. Atomic Energy Research Establishment. R/M 165, 1958.Google Scholar
22. Martens, H. E., and Kotlevsky, W. V. Tensile Behaviour of Pyrolytic Graphite at 2,750°C. Nature, Vol. 186, p. 960, 1960.CrossRefGoogle Scholar
23. Hennig, G. R. Electron Microscope Studies of Graphite Crystals. Proceedings of the Fourth International Conference on Carbon, Buffalo, 1959. (In the press).Google Scholar