Chapter 3. Evaluation of Ammonia Treated Nextel™ 312 Fiber -Blackglas™ Matrix Composites
- John B. Wachtman Jr.
Published Online: 26 MAR 2008
Copyright © 1995 The American Ceramic Society
Proceedings of the 19th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures - B: Ceramic Engineering and Science Proceedings, Volume 16, Issue 5
How to Cite
Khasgiwale, N. R., Butler, E. P., Vaidyanathan, K. R., Tsakalakos, L., Cannon, W. R., Danforth, S. C. and Gonczy, S.T. (1995) Evaluation of Ammonia Treated Nextel™ 312 Fiber -Blackglas™ Matrix Composites, in Proceedings of the 19th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures - B: Ceramic Engineering and Science Proceedings, Volume 16, Issue 5 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470314784.ch3
- Published Online: 26 MAR 2008
- Published Print: 1 JAN 1995
Print ISBN: 9780470375389
Online ISBN: 9780470314784
Contrary to the generally observed behavior in ceramic-ceramic composites, Nextel™312 fiber- BN -Blackglas™ matrix composites show no loss in flexural strength, an increase in failure strain and increased fibrous failure after oxidation at 600°C for 100 hours. In order to understand this phenomenon, the interfaces of the ammonia treated Nextel™312 fiber — BN -Blackglas™ matrix composites were evaluated in the as prepared condition and after oxidation at 600°C for 5, 24, 100, 200 and 1000 hours. The combined effect of stress and temperature was evaluated on pre-oxidized samples (oxidized at 600°C for 100 hours) stressed to failure at 566°C. In the as prepared composites a smooth interface between the fiber and the matrix was observed. No reaction was observed between the BN rich surface of the fiber and the Blackglas™ matrix. Similar observations were made on samples oxidized for 5, 24, 200 and 1000 hours. Samples oxidized for 200 hours showed matrix regions that were depleted in carbon. Long term oxidation (1000 hours) resulted in almost complete depletion of carbon from the matrix. Samples tested under stress again did not show a reaction zone between the fiber and the matrix, however precipitates were observed in the Blackglas™ matrix. Based on the observations of the long term oxidized and creep samples the observed changes in mechanical properties most likely can attributed to changes occurring in the matrix chemistry.