Chapter 42. Microstructure and Environmental Stability of Si3N4 Sintered with Mixed Y2O3, MgO, and Cr2O3 Additives

  1. John B. Wachtman Jr
  1. K. P. Plucknett,
  2. N. D. Butler and
  3. M. H. Lewis

Published Online: 26 MAR 2008

DOI: 10.1002/9780470313848.ch42

Proceedings of the 15th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 12, Issue 9/10

Proceedings of the 15th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 12, Issue 9/10

How to Cite

Plucknett, K. P., Butler, N. D. and Lewis, M. H. (1991) Microstructure and Environmental Stability of Si3N4 Sintered with Mixed Y2O3, MgO, and Cr2O3 Additives, in Proceedings of the 15th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 12, Issue 9/10 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470313848.ch42

Author Information

  1. Centre for Advanced Materials Technology University of Warwick Coventry, UK

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 1991

ISBN Information

Print ISBN: 9780470375105

Online ISBN: 9780470313848

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Keywords:

  • microstructure;
  • crystallization;
  • nitride;
  • viscosity;
  • encapsulation

Summary

The microstructural evolution of an Si3N4 ceramic pressureless sintered with Y2O3, MgO, and Cr2O3 additives has been studied. Two basic processing variables were investigated: sintered Si3N4 (SSN), starting with Si3N4 powder, and sintered reaction bonded Si3N4 (SRBSN), starting with silicon powder. Glass-encapsulated hot isostatic pressing (HIPSN) of SSN-type preforms was also examined, resulting in a finer grain structure than the pressureless sintered equivalent. The lower oxygen content of the SRBSN materials had only a minimal effect upon the observed microstructure relative to SSN materials. However, considerable variation in oxidation behavior was apparent, with partial matrix crystallization to Y2Si2O7 in the SSN ceramic and crystallization to a mixed cation phase in SRBSN variants.