Chapter 10. Secondary Phase Devitrification Effects Upon the Static Fatigue Resistance of Sintered Silicon Nitride

  1. John B. Wachtman Jr.
  1. George D. Quinn1 and
  2. Wolfgang R. Braue2

Published Online: 26 MAR 2008

DOI: 10.1002/9780470313008.ch10

A Collection of Papers Presented at the 14th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 11, Issue 7/8

A Collection of Papers Presented at the 14th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 11, Issue 7/8

How to Cite

Quinn, G. D. and Braue, W. R. (1990) Secondary Phase Devitrification Effects Upon the Static Fatigue Resistance of Sintered Silicon Nitride, in A Collection of Papers Presented at the 14th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 11, Issue 7/8 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470313008.ch10

Author Information

  1. 1

    U.S. Army Materials Technology Laboratory (MTL) Watertown, MA 02172

  2. 2

    German Aerospace Research Establishment (DLR) 5000 Cologne 90 Federal Republic of Germany

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 1990

ISBN Information

Print ISBN: 9780470374924

Online ISBN: 9780470313008

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Keywords:

  • silicon nitride;
  • residual glass;
  • mechanism;
  • sintering;
  • oxidation

Summary

Static fatigue resistance of SNW-1000 grade sintered silicon nitride which has yttria and alumina sintering aids was dramatically improved when the initially amorphous boundary phase devitrified during stress rupture testing. The principal devitrification products in the high tensile stressed regions were δ-Y2Si2O7 and nitrogen apatite, although some residual glass was still present. The static fatigue and creep resistances at higher temperatures (>1200°C) are limited by both the residual glassy phase and the δ-Y2Si2O7. The stress-temperature ranges where this devitrification occurs, and the regimes where slow crack growth or creep fracture occur, can be depicted on a fracture mechanism map.