Chapter 45. Crack Healing in Silicon Nitride Due to Oxidation
- John B. Wachtman Jr
Published Online: 26 MAR 2008
Copyright © 1991 The American Ceramic Society, Inc.
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
- Published Online: 26 MAR 2008
- Published Print: 1 JAN 1991
Print ISBN: 9780470375105
Online ISBN: 9780470313848
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.