Chapter 6. Synthesis and Thermal Stability of a Si-N-(O) Fiber

  1. J. P. Singh
  1. Ulrich Vogt,
  2. Georg Chollon and
  3. Karl Berroth

Published Online: 26 MAR 2008

DOI: 10.1002/9780470294437.ch6

Proceedings of the 21st Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: A: Ceramic Engineering and Science Proceedings, Volume 18, Issue 3

Proceedings of the 21st Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: A: Ceramic Engineering and Science Proceedings, Volume 18, Issue 3

How to Cite

Vogt, U., Chollon, G. and Berroth, K. (1997) Synthesis and Thermal Stability of a Si-N-(O) Fiber, in Proceedings of the 21st Annual Conference on Composites, Advanced Ceramics, Materials, and Structures: A: Ceramic Engineering and Science Proceedings, Volume 18, Issue 3 (ed J. P. Singh), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470294437.ch6

Author Information

  1. Swiss Federal Laboratories for Materials Testing and Research (EMPA), Überlandstrasse 129, CH-8600 Dübendorf, Switzerland.

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 1997

ISBN Information

Print ISBN: 9780470375495

Online ISBN: 9780470294437

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Keywords:

  • silicon nitride;
  • dissociation;
  • thermal stability;
  • annealing;
  • thermal shock

Summary

Silicon nitride based fibers which are capable of withstanding high temperature applications can be produced by a high temperature CVD-process. The overall reaction (3SiO2 + 4NH3 [RIGHTWARDS ARROW] Si3N4 + 6H2O) operates at temperatures between 1400–1500°C by the dissociation of NH3 and through the formation of SiO from SiO2. Tensile strength of the flexible amorphous fibers with 5m̈m in diameter reach values up to 5GPa. The thermal stability of the amorphous silicon nitride based fibers was studied in argon, nitrogen and oxygen atmospheres. The fibers are stable in nitrogen up to 1450°C (10h) in terms of composition, structure, and mechanical behaviour. In argon, decomposition starts at 1400°C yielding gaseous species (SiO, N2), crystalline Si3N4 and free silicon. Annealing in oxygen results in the growth of a protective amorphous SiO2 layer which starts to crystallise above 1400°C. Initial incorporation of the fibers in CMCs by CVI- and RBSN-processes shows promising results.