Chapter 4. Effects of Prior Cyclic Loading on the Strength of HIPed Silicon Nitride

  1. John B. Wachtman Jr.
  1. R. Berriche and
  2. R. T. Holt

Published Online: 28 MAR 2008

DOI: 10.1002/9780470314555.ch4

Proceedings of the 18th Annual Conference on Composites and Advanced Ceramic Materials - B: Ceramic Engineering and Science Proceedings, Volume 15, Issue 5

Proceedings of the 18th Annual Conference on Composites and Advanced Ceramic Materials - B: Ceramic Engineering and Science Proceedings, Volume 15, Issue 5

How to Cite

Berriche, R. and Holt, R. T. (1994) Effects of Prior Cyclic Loading on the Strength of HIPed Silicon Nitride, in Proceedings of the 18th Annual Conference on Composites and Advanced Ceramic Materials - B: Ceramic Engineering and Science Proceedings, Volume 15, Issue 5 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470314555.ch4

Author Information

  1. Institute for Aerospace Research, National Research Council, Ottawa, Canada, K1A 0R6

Publication History

  1. Published Online: 28 MAR 2008
  2. Published Print: 1 JAN 1994

ISBN Information

Print ISBN: 9780470375334

Online ISBN: 9780470314555

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Keywords:

  • cyclic loading;
  • hot isostatically pressed;
  • cyclic stresses;
  • flexural strength;
  • fast-fracture strength

Summary

The strength of hot isostatically pressed (HIPed) silicon nitride (NT-154 produced by Norton/TRW Ceramics) was investigated after cyclic loading at room temperature and elevated temperatures. Four point bend fatigue tests were conducted in load control at an R ratio of 0.1 and a frequency of 1 Hz. The accumulated fatigue damage was assessed by stopping the test after a certain number of cycles and measuring the flexure strength at room temperature in stroke control. The effects of (i) number of cycles, (ii) maximum applied stress and (iii) temperature of cyclic loading have been studied. Increasing the temperature in the range 1200 to 1400 °C had the most detrimental effect on the residual strength. The results are explained in terms of microstructural changes.