Chapter 29. Silsesquioxanes as Precursors to Ceramic Composites

  1. William Smothers
  1. F. I. Hurwitz,
  2. L. Hyatt,
  3. J. Gorecki and
  4. L. D'Amore

Published Online: 26 MAR 2008

DOI: 10.1002/9780470320402.ch29

11th Annual Conference on Composites and Advanced Ceramic Materials: Ceramic Engineering and Science Proceedings, Volume 8, Issue 7/8

11th Annual Conference on Composites and Advanced Ceramic Materials: Ceramic Engineering and Science Proceedings, Volume 8, Issue 7/8

How to Cite

Hurwitz, F. I., Hyatt, L., Gorecki, J. and D'Amore, L. (1987) Silsesquioxanes as Precursors to Ceramic Composites, in 11th Annual Conference on Composites and Advanced Ceramic Materials: Ceramic Engineering and Science Proceedings, Volume 8, Issue 7/8 (ed W. Smothers), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470320402.ch29

Author Information

  1. NASA Lewis Research Center 21000 Brookpark Rd. Cleveland, OH 44135

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 1987

ISBN Information

Print ISBN: 9780470374733

Online ISBN: 9780470320402

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Keywords:

  • silsesquioxanes;
  • pyrolysis;
  • carbothermal;
  • precursors;
  • polysilsesquioxane

Summary

Silsesquioxanes having the general structure RSiO1.5, where R = methyl, propyi or phenyl, melt flow at 70°–100°C. Above 100°C, free-OH groups condense. At 225°C further crosslinking occurs, and the materials form thermosets. Pyrolysis, with accompanying loss of volatiles, takes place at nominally 525°C. At higher temperatures, the R group serves as an internal carbon source for carbothermal reduction to SiC accompanied by the evolution of CO. By bending Silsesquioxanes with varying R groups, both the melt rheology and composition of the fired ceramic can be controlled. Fibers can be spun from the melt which are stable in argon to 1400°C. The silsesquioxanes also have been used as matrix precursors for Nicalon and α-SiC platelet reinforced composites.