Chapter 29. Oxidation Effects on Nextel™-Reinforced SiC
- John B. Wachtman Jr.
Published Online: 28 MAR 2008
Copyright © 1994 The American Ceramic Society
Proceedings of the 18th Annual Conference on Composites and Advanced Ceramic Materials - A: Ceramic Engineering and Science Proceedings, Volume 15, Issue 4
How to Cite
Tortorelli, P. F., Wijayawardhana, C. A., Riester, L. and Lowden, R. A. (1994) Oxidation Effects on Nextel™-Reinforced SiC, in Proceedings of the 18th Annual Conference on Composites and Advanced Ceramic Materials - A: Ceramic Engineering and Science Proceedings, Volume 15, Issue 4 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470314500.ch29
- Published Online: 28 MAR 2008
- Published Print: 1 JAN 1994
Print ISBN: 9780470375327
Online ISBN: 9780470314500
The oxidation reactions associated with air exposures of Nextel™-reinforced SiC composites with carbon and BN fiber coatings (interphases) were studied by thermogravimetric analysis. For those with carbon interphases, the shapes of the thermogravimetric curves could be explained on the basis of concurrent reactions associated with oxidation of the carbon and the formation of SiO2. The use of BN fiber coatings improved oxidation resistance because there was no weight loss associated with carbon oxidation. Oxidation reactions led to significant changes in the mechanical behavior of a Nextel™-reinforced SiC composite with carbon interphases. Room-temperature flexure testing after air oxidation showed rapid degradation of the first matrix cracking stress and strength (within the first hour of exposure) and more gradual deterioration of the amount of pullout accompanying fracture. Because changes in the mechanical behavior of SiC composites with carbon interphases occur very rapidly, appropriate exposure periods are required to correcdy predict the rate of degradation of composite properties by oxidation.