Chapter 45. Crack Healing in Silicon Nitride Due to Oxidation

  1. John B. Wachtman Jr
  1. Sung R. Choi1,
  2. Veena Tikare2 and
  3. Ralph Pawlik2

Published Online: 26 MAR 2008

DOI: 10.1002/9780470313848.ch45

Proceedings of the 15th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 12, Issue 9/10

Proceedings of the 15th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 12, Issue 9/10

How to Cite

Choi, S. R., Tikare, V. and Pawlik, R. (1991) Crack Healing in Silicon Nitride Due to Oxidation, in Proceedings of the 15th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 12, Issue 9/10 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470313848.ch45

Author Information

  1. 1

    Cleveland State University Cleveland, OH 44115

  2. 2

    NASA Lewis Research Center Cleveland, OH 44135

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 1991

ISBN Information

Print ISBN: 9780470375105

Online ISBN: 9780470313848

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Keywords:

  • temperature;
  • cristobalite;
  • environment;
  • phenomenon;
  • perpendicular

Summary

The crack healing behavior of a commercial, MgO-containing, hot pressed Si3N4 was studied as a function of temperature in oxidizing and inert annealing environments. Crack healing occurred at temperature ≈800°C due to oxidation regardless of crack size, which ranged from 100 m̈m (indentation crack) to 1.7 mm (SEPB precrack). The resulting strength and apparent fracture toughness increased at crack healing temperature by 100% and 300%, respectively. The oxide layer present in the crack plane was found to be highly fatigue resistant, indicating that the oxide is not solely silicate glass, but a mixture of glass, enstatite, and/or cristobalite that was insensitive to fatigue in a room temperature water environment.