Chapter 3. High-Resolution Electron Microscopy of Precycled Samples of a Sintered Silicon Nitride

  1. John B. Wachtman Jr.
  1. Jayant Neogi,
  2. Suneeta S. Neogi,
  3. Jag Sankar and
  4. Ranji Vaidyanathan

Published Online: 28 MAR 2008

DOI: 10.1002/9780470314555.ch3

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

Neogi, J., Neogi, S. S., Sankar, J. and Vaidyanathan, R. (1994) High-Resolution Electron Microscopy of Precycled Samples of a Sintered 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.ch3

Author Information

  1. Department of Mechanical Engineering, North Carolina A&T State University, Greensboro, NC 27411

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:

  • high-resolution electron microscopy;
  • fatigue and tensile loads;
  • multi-grain junctions;
  • grain-boundary film thickness;
  • silicon nitride ceramics

Summary

Significant progress has been made in the recent years in developing sintered silicon nitride structural ceramics for heat engine applications due to their excellent high temperature mechanical properties. Studies showed that precycling improved significantly the high temperature tensile strength in sintered silicon nitride (GTE SNW-1000). High-resolution electron microscopy (HREM) was used to study specimens subjected to a combination of fatigue and tensile loads. The high temperature mechanical behavior was found to be controlled by the presence of amorphous phases along grain boundaries and multi-grain junctions. Precycling at elevated temperature led to nearly complete crystallization of the amorphous phases at the multi-grain junctions which is thought to be a reason for the observed improvement in tensile strength. It was observed that the material exhibited an equilibrium thickness of the grain-boundary film. It was shown that the grain-boundary film thickness was affected due to precycling at elevated temperature.