Chapter 38. Mechanical Properties Data Requirements for Life Prediction Methodologies of Ceramic Materials Under Creep
- John B. Wachtman Jr.
Published Online: 28 MAR 2008
Copyright © 1993 The American Ceramic Society
Proceedings of the 17th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 14, Issue 7/8
How to Cite
Liu, K. C., Stevens, C. O. and Brinkman, C. R. (1993) Mechanical Properties Data Requirements for Life Prediction Methodologies of Ceramic Materials Under Creep, in Proceedings of the 17th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 14, Issue 7/8 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470314180.ch38
- Published Online: 28 MAR 2008
- Published Print: 1 JAN 1993
Print ISBN: 9780470375266
Online ISBN: 9780470314180
- subcritical stress region;
Creep properties of ceramic materials that are able to deform by localized intergranular slip are highly dependent upon applied stress at creep temperature. Time-dependent deformation in such materials may be categorized into three groups based upon the observed relationship between creep rate and stress: (1) subcritical stress region, in which a large stress exponent, n, is observed, (2) creep region, where n values typically fall between 3 and 6, and (3) stress rupture region, where a large stress exponent is again observed and specimen failure is dominated by crack propagation from defects and void formation. Region 1 is not a cause of concern in design applications. The stress at which the transition from region 2 to region 3 takes place depends on grain size, the level of residual amorphous phase in the grain boundary phases, and temperature. Variability of life prediction is expected to be influenced by the variability of the transition stress, which is lot-dependent. Experimental results will be used to develop the parameters that characterize the transition behavior in several lots of silicon nitride ceramics and to evaluate the predictability of existing methodologies.