Chapter 28. Nicalon/Siliconoxycarbide Ceramic Composites
- John B. Wachtman Jr.
Published Online: 26 MAR 2008
Copyright © 1990 The American Ceramic Society, Inc.
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
Hurwitz, F. I., Gyekenyesi, J. Z., Conroy, P. J. and Rivera, A. L. (1990) Nicalon/Siliconoxycarbide Ceramic Composites, 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.ch28
- Published Online: 26 MAR 2008
- Published Print: 1 JAN 1990
Print ISBN: 9780470374924
Online ISBN: 9780470313008
- methyl/phenyl ratios;
A series of silsesquioxane copolymers has been synthesized by acid hydrolysis and condensation of trimethoxysilanes of the form RSi(OCH3)3, where R = methyl or phenyl. By varying pH, water/methoxy, and methyl/phenyl ratios, the molecular structure, polymer rheology, and ceramic composition can be controlled. The polymers form an amorphous siliconoxycarbide on pyrolysis.
Composites of Nicalon/siliconoxycarbide were fractured in 4-pt. flexure and in tension to evaluate the influence of matrix composition, final fabrication temperature, and use of filler on composite mode of failure, modulus, strain capability, and strength. Incorporation of filler was found to increase matrix compressive strength. Employment of processing temperatures of 1375°–1400°C enhanced strain-to-failure and reduced the tendency toward brittle fracture. Mixed-mode (compression/shear and tension/shear) failures were observed in flexural samples processed to the higher temperatures, giving rise to nonlinear stress-strain curves. Tensile samples pyrolyzed to 1400°C showed linear-elastic behavior and failed by fracture of fiber bundles. Matrix material was found to be adherent to the fiber surface after failure. These results demonstrate the need for tensile testing to establish composite behavior.