Chapter 16. Indentation Fracture of Silicon Carbide Whisker-Reinforced Silicon Nitride Ceramic Matrix Composites (CMC's)

  1. John B. Wachtman Jr.
  1. A. G. Solomah1 and
  2. L. Espositol2

Published Online: 26 MAR 2008

DOI: 10.1002/9780470313978.ch16

Proceedings of the 16th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 13, Issue 9/10

Proceedings of the 16th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 13, Issue 9/10

How to Cite

Solomah, A. G. and Espositol, L. (1994) Indentation Fracture of Silicon Carbide Whisker-Reinforced Silicon Nitride Ceramic Matrix Composites (CMC's), in Proceedings of the 16th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 13, Issue 9/10 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470313978.ch16

Author Information

  1. 1

    SAC International Ceramics, Mississauga, Ontario L5T 1V3 CANADA

  2. 2

    Italian Ceramic Centre, Bologna, 40138 ITALY

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 1994

ISBN Information

Print ISBN: 9780470375198

Online ISBN: 9780470313978

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Keywords:

  • submicrometer;
  • densification;
  • sintering;
  • concentration;
  • elevated

Summary

Vickers indentation technique has been used to characterize the fracture behavior of silicon carbide whisker-reinforced silicon nitride ceramic matrix composites (CMC's) manufactured by hot-isostatic and hot-uniaxial pressing techniques. Indentations were performed at room temperature under ambient atmosphere having 40% relative humidity and an oil film coat to prevent environmental effects on post-indentation slow-crack growth behavior. Hardness was found to decrease with indentation load, a typical behavior of hard brittle materials. The relationship between crack length, c, and indentation load, P, was found to have the formula: C ∞ pq, where the value of q depends on the orientation of silicon carbide whiskers throughout the specified plane on which indentations were performed. Significant differences in post-indentation slow-crack growth behavior between indentations performed under a humid atmosphere and under an oil film coat were observed showing an environmental effect-assisted crack propagation, i.e. stress corrosion-assisted propagation. Comparison with a monolithic Si3N4 prepared by hot-isostatic pressing has shown that the addition of SiC whiskers significantly improves its slow-crack growth resistance.