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Journal of Materials Science

, Volume 32, Issue 4, pp 1039–1047 | Cite as

Effects of thermal cycling on thermal expansionand mechanical properties of SiC fibre-reinforced reaction-bonded Si3N4 composites

  • R.T BHATT
  • A.R PALCZER
Article

Abstract

Thermal expansion curves for SiC fibre-reinforced reaction-bonded Si3N4 matrix composites (SiC/RBSN) and unreinforced RBSN were measured from 25 to 1400 °C in nitrogen and in oxygen. The effects of fibre/matrix bonding and cycling on the thermal expansion curves and room-temperature tensile properties of unidirectional composites were determined. The measured thermal expansion curves were compared with those predicted from composite theory. Predicted thermal expansion curves parallel to the fibre direction were between the measured curves for the strongly- and weakly-bonded composites, but those normal to the fibre direction for both bonding cases were similar to that of the unreinforced RBSN. Thermal cycling in nitrogen for both bonding cases resulted in no net dimensional changes at room temperature and no loss in tensile properties from the as-fabricated condition. In contrast, thermal cycling in oxygen for both composites caused volume expansion primarily due to internal oxidation of RBSN. Cyclic oxidation affected the mechanical properties of the weakly-bonded SiC/RBSN composites the most, resulting in loss of strain capability beyond matrix fracture and catastrophic, brittle fracture. Increased bonding between the SiC fibre and RBSN matrix due to oxidation of the carbon-rich fibre surface coating and an altered residual stress pattern in the composite due to internal oxidation of the matrix are the main reasons for the poor mechanical performance of these composites.

Keywords

Residual Stress Internal Oxidation Silica Layer Cyclic Oxidation Interfacial Shear Strength 

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References

  1. 1.
    C. A. ANDERSON, P. BORRON-ANTOLIN, A. S. FAREED and G. H. SCHIROKY, in “Whisker-and Fiber-Toughened Ceramics” edited by R. A. Bradley, D. E. Clark, D. C. Larsen, and J. O. Stiegler (American Society for Metals International, Metals Park, OH, 1988) p. 209.Google Scholar
  2. 2.
    R. T. BHATT and R. E. PHILLIPS, J. Compos. Technol. Res. 12 (1990) 13.CrossRefGoogle Scholar
  3. 3.
    W. FOULDS, J. F. LECOSTAOUEC, C. LANDRY, S. DIPIETRO and T. VASILOS, Ceram. Eng. Sci. Proc. 10 (1989) 1083.CrossRefGoogle Scholar
  4. 4.
    P. I. LIMICQ, G. A. BERNHART, M. M. DAUCHIER and J. G. MACE, Amer. Cer. Soc. Bull. 65 (1986) 336.Google Scholar
  5. 5.
    K. M. PREWO and J. J. BRENNAN, J. Mater. Sci. 15 (1980) 463.CrossRefGoogle Scholar
  6. 6.
    R. T. BHATT, in “Whisker-and Fiber-Toughened Ceramics”, edited by R. A. Bradley, D. E. Clark, D. C. Larsen, and J. O. Stiegler (American Society for Materials International, Metals Park, OH, 1988) p. 209.Google Scholar
  7. 7.
    P. PIROUZ, G. MORSCHER and J. CHANG, in “Surface and Interfaces of Ceramic Materials” edited by L. C. Dufour (Kluwer Academic Publishers, Dordrecht, 1989) p. 737.CrossRefGoogle Scholar
  8. 8.
    R. T. BHATT, US Patent No. 4689188 (1987).Google Scholar
  9. 9.
    J. ELDRIDGE, private communication.Google Scholar
  10. 10.
    R. A. SCHAPERY, J. Compos. Mater. 2 (1968) 380.CrossRefGoogle Scholar
  11. 11.
    P. S. TURNER, J. Res. Nat. Bur. Stand. (US) 37 (1946) 239.CrossRefGoogle Scholar
  12. 12.
    J. A. DICARLO, in “Whisker-and Fiber-Toughened Ceramics”, edited by R. A. Bradley, D. E. Clark, D. C. Larsen, and J. O. Stiegler (American Society for Materials International, Metals Park, OH, 1988) p. 1.Google Scholar
  13. 13.
    W. S. COBLENZ, J. Amer. Ceram. Soc. 58 (1975) 530.CrossRefGoogle Scholar
  14. 14.
    F. PORZ and F. THUMMLER, J. Mater. Sci. 19 (1984) 1283.CrossRefGoogle Scholar
  15. 15.
    A. G. EVANS and R. W. DAVIDGE, ibid. 5 (1970) 314.CrossRefGoogle Scholar
  16. 16.
    R. T. BHATT, J. Amer. Ceram. Soc. 75 (1992) 406.CrossRefGoogle Scholar

Copyright information

© Chapman and Hall 1997

Authors and Affiliations

  • R.T BHATT
    • 1
  • A.R PALCZER
    • 1
  1. 1.NASA Lewis Research CenterClevelandUSA

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