Chapter 38. Mechanical Properties Data Requirements for Life Prediction Methodologies of Ceramic Materials Under Creep

  1. John B. Wachtman Jr.
  1. K. C. Liu,
  2. C. O. Stevens and
  3. C. R. Brinkman

Published Online: 28 MAR 2008

DOI: 10.1002/9780470314180.ch38

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

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

Author Information

  1. Edited by C.R. Brinkman and S.F. Duffy. ASTM STP 1201, American Society for Testing and Materials, Philadelphia, 1993.

Publication History

  1. Published Online: 28 MAR 2008
  2. Published Print: 1 JAN 1993

ISBN Information

Print ISBN: 9780470375266

Online ISBN: 9780470314180

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Keywords:

  • deformation;
  • subcritical stress region;
  • transition;
  • variability;
  • characterize

Summary

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.