Chapter 56. Stress Relaxation of Silicon Nitride at Elevated Temperatures

  1. John B. Wachtman Jr
  1. A. A. Wereszczak1,
  2. M. K. Ferber1,
  3. T. P. Kirkland1,
  4. E. Lara-Curzio1,
  5. V. Parthasarathy1 and
  6. T. T. Gribb3

Published Online: 26 MAR 2008

DOI: 10.1002/9780470314715.ch56

Proceedings of the 19th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures - A: Ceramic Engineering and Science Proceedings, Volume 16, Issue 4

Proceedings of the 19th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures - A: Ceramic Engineering and Science Proceedings, Volume 16, Issue 4

How to Cite

Wereszczak, A. A., Ferber, M. K., Kirkland, T. P., Lara-Curzio, E., Parthasarathy, V. and Gribb, T. T. (1995) Stress Relaxation of Silicon Nitride at Elevated Temperatures, in Proceedings of the 19th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures - A: Ceramic Engineering and Science Proceedings, Volume 16, Issue 4 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470314715.ch56

Author Information

  1. 1

    High Temperature Materials Laboratory Oak Ridge National Laboratory Oak Ridge, TN 37831-6069

  2. 3

    Materials Science & Engineering Dept. University of Wisconsin Madison, WI 53706

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 1995

ISBN Information

Print ISBN: 9780470375372

Online ISBN: 9780470314715

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Keywords:

  • silicon nitride;
  • buttonhead;
  • algorithm;
  • creep;
  • elevated

Summary

The stress relaxation behavior of SN88, SN2S3, and NCX-5102 silicon nitride materials were experimentally determined in tension at 1300°C using buttonhead specimens. Specimens were held at constant strain after being loaded at 10 MPa/s to an initial stress of 276 MPa (40 ksi) or 414 MPa (60 ksi). The subsequent decay in tensile stress was measured as a function of time. A non-negative least squares algorithm used in conjunction with a generalized Maxwell model proved to be an efficient means to define characteristic relaxation modulus spectra and stress relaxation behavior. In the last part of this study, the utility of using short-term stress relaxation testing to predict long-term creep performance was examined.