Chapter 45. Creep Crack Growth in SiC Whisker-Reinforced Si3N4

  1. John B. Wachtman Jr.
  1. Karl Jakus,
  2. Christine E. Weigand,
  3. Michael H. Godin and
  4. Shantikumar V. Nair

Published Online: 28 MAR 2008

DOI: 10.1002/9780470310588.ch45

A Collection of Papers Presented at the 13th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 10, Issue 9/10

A Collection of Papers Presented at the 13th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 10, Issue 9/10

How to Cite

Jakus, K., Weigand, C. E., Godin, M. H. and Nair, S. V. (1989) Creep Crack Growth in SiC Whisker-Reinforced Si3N4, in A Collection of Papers Presented at the 13th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 10, Issue 9/10 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470310588.ch45

Author Information

  1. University of Massachusetts Amherst, MA

Publication History

  1. Published Online: 28 MAR 2008
  2. Published Print: 1 JAN 1989

ISBN Information

Print ISBN: 9780470374870

Online ISBN: 9780470310588

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Keywords:

  • silica fiber;
  • organic epoxies;
  • sealing process;
  • silicon fiber;
  • seal fiber-optics

Summary

Creep crack growth in an SiC whisker-reinforced Si3N4 composite was studied at 137°C in air. Indentation cracks on tensile surface of four-point bend specimens were monitored by periodic interruption of the creep test up to 0.84% creep strain. The growth rate of individual cracks was found to fluctuate with time resulting in relatively large scatter among the velocities of the different cracks placed on the tensile surface. This fluctuation was apparently caused by intermittent breaking of crack bridging ligaments that were formed by the nucleation of microcracks ahead of the main crack. On the average, the crack growth rate was only slightly sensitive to the apparent stress intensity factor, with a velocity exponent of 1.9, but showed a strong linear correlation with the measured creep strain rate. The relationship between velocity and creep strain rate could be of considerable importance in predicting component life made of this composite.