Chapter 38. Influence of the Si3N4 Microstructure on Its R-Curve and Fatigue Behavior

  1. John B. Wachtman Jr
  1. Veena Tikare and
  2. Sung R. Choi

Published Online: 28 MAR 2008

DOI: 10.1002/9780470313831.ch38

Proceedings of the 15th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 12, Issue 7/8

Proceedings of the 15th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 12, Issue 7/8

How to Cite

Tikare, V. and Choi, S. R. (2008) Influence of the Si3N4 Microstructure on Its R-Curve and Fatigue Behavior, in Proceedings of the 15th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 12, Issue 7/8 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470313831.ch38

Author Information

  1. NASA Lewis Research Center Cleveland, OH 44135

Publication History

  1. Published Online: 28 MAR 2008
  2. Published Print: 1 JAN 1991

ISBN Information

Print ISBN: 9780470375099

Online ISBN: 9780470313831

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Keywords:

  • microstructure;
  • mechanisms;
  • propagation;
  • ceramographic;
  • microscopy

Summary

Silicon nitrides with highly elongated grains have gained much attention as engineering materials for use in high-temperature structural applications. The R-curve and fatigue behavior of a silicon nitride with large, highly elongated grains were compared to those of a silicon nitride with smaller, more equiaxed grains. The former was found to have higher toughess and a slightly rising R-curve which enhanced fatigue resistance, while the latter had constant toughness with crack length. The R-curve was atrributed to crack deflection and grain pull-out. The microstructure did not influence the dynamic fatigue properties of the two ceramics as both had good resistance to dynamic fatigue. The cyclic fatigue resistance of the large-grained Si3N4, however, was surprisingly low.