Chapter 36. Post-Indentation Subcritical (Slow) Crack Growth in Whisker-Reinforced Silicon Nitride Ceramic Matrix Composites
- John B. Wachtman Jr.
Published Online: 26 MAR 2008
Copyright © 1996 The American Ceramic Society
Proceedings of the 20th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures - A: Ceramic Engineering and Science Proceedings, Volume 17, Issue 3
How to Cite
Solomah, A. G., Tucci, A. and Esposito, L. (1996) Post-Indentation Subcritical (Slow) Crack Growth in Whisker-Reinforced Silicon Nitride Ceramic Matrix Composites, in Proceedings of the 20th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures - A: Ceramic Engineering and Science Proceedings, Volume 17, Issue 3 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470314821.ch36
- Published Online: 26 MAR 2008
- Published Print: 1 JAN 1996
Print ISBN: 9780470375426
Online ISBN: 9780470314821
The phenomenon of post-indentation subcritical (slow) crack growth in silicon carbide whisker-reinforced silicon nitride ceramic matrix composites has been investigated under inert and humid ambient atmospheres. The residual component of the stress field of the sharp Vickers indentation has been shown to have a little effect on crack extension after unloading. However, the humid atmosphere plays a significant role, due to Stress Corrosion-Assisted Crack Propagation (SCACP) at the crack tip. The so-called well-developed crack, i.e. c≥b or c/a>2, where c is the crack length measured from the centre of indentation diagonal and a and b are the half-diagonal length and the radius of the plastic zone as defined by Lawn, Evans and Marshall, is an inappropriate term used to define the type of the crack developed after indentation process. It is recommended that a thorough and systematic analysis is required to correlate the micro-structural features of a specific “material to the shape and evolution of the crack during and after indentation, after excluding the environmental effects on crack growth, which dominate the equilibrium” shape and the type of the crack.