Chapter 11. Cyclic Fatigue of Silicon Nitrides
- John B. Wachtman Jr.
Published Online: 26 MAR 2008
Copyright © 1989 The American Ceramic Society, Inc.
A Collection of Papers Presented at the 13th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 10, Issue 7/8
How to Cite
Nlkkila, A. .-P. and Mäntyla, T. A. (1989) Cyclic Fatigue of Silicon Nitrides, in A Collection of Papers Presented at the 13th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 10, Issue 7/8 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470310557.ch11
- Published Online: 26 MAR 2008
- Published Print: 1 JAN 1989
Print ISBN: 9780470374863
Online ISBN: 9780470310557
- silicon nitride;
- fatigue behavior;
- chemical vapor infiltration;
- compression stresses;
- weibull modulus
Cyclic fatigue behavior of three different silicon nitrides, one hot-pressed and two sintered, were studied. To avoid the difficulties of fatigue test of brittle ceramics in pull-push test, a special 4-point bending jig was constructed. The tests were made at room temperature. Effects of compression stresses were studied using three different fatigue test modes: 1) sinusoidal R=-l (tension-compression); 2) sinusoidal R=0 (tension); and 3) positive half sinusoidal R=0 (tension), in which the negative part of the loading cycle is cut off. Lowest fatigue strengths were obtained by loading mode 1, cyclic tension compression mode, which indicate that compressive stresses also are effective in advancing the growth of subcritical crack. The fatigue resistance of studied hot pressed silicon nitride was higher than the resistance of studied sintered silicon nitrides. Long fatigue lives can be expected for these materials at stress levels lower than 2/3 of the bend strength. When subcritical crack extension parameter n was calculated from experimental results, values between 31 and 43 were obtained from cyclic tests. Dynamic fatigue test gave much higher values, e.g., n=95 for one of the sintered silicon nitrides.