22. Oxidation Kinetics and Strength Degradation of Carbon Fibers in a Cracked Ceramic Matrix Composite

  1. Edgar Lara-Curzio and
  2. Michael J. Readey
  1. Michael C. Halbig

Published Online: 26 MAR 2008

DOI: 10.1002/9780470291191.ch22

28th International Conference on Advanced Ceramics and Composites B: Ceramic Engineering and Science Proceedings, Volume 25, Issue 4

28th International Conference on Advanced Ceramics and Composites B: Ceramic Engineering and Science Proceedings, Volume 25, Issue 4

How to Cite

Halbig, M. C. (2004) Oxidation Kinetics and Strength Degradation of Carbon Fibers in a Cracked Ceramic Matrix Composite, in 28th International Conference on Advanced Ceramics and Composites B: Ceramic Engineering and Science Proceedings, Volume 25, Issue 4 (eds E. Lara-Curzio and M. J. Readey), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470291191.ch22

Author Information

  1. Army Research Laboratory NASA Glenn Research Center 21000 Brookpark Road, MS 106-1 Cleveland, OH 44135

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 2004

ISBN Information

Print ISBN: 9780470051528

Online ISBN: 9780470291191

SEARCH

Keywords:

  • ceramic matrix composites;
  • carbon constituents;
  • thermogravimetric analysis;
  • carbon fiber;
  • oxidation kinetics

Summary

The oxidation of the carbon within C/SiC decreases strength and life which inhibits its utilization in long-term (100 hr), reusable applications. Before promising protection methods can be evaluated for preventing carbon oxidation, it is useful to first study the oxidation problem. The oxidation rates of the carbon constituents (T300 carbon fiber and pyrolytic carbon interphase) within C/SiC were studied individually and together. The testing identified the oxidation kinetic regimes for the two individual carbon constituents and the effects of crack closure in C/SiC when no stress is applied. Pre-exposures of tensile coupons and residual strength tests allowed for the amount of carbon consumed to be quantified and for the effects on strength reduction to be determined. Stressed oxidation tests allowed for the material to be tested under more harsh conditions in which the as-fabricated cracks in the matrix and external coating are held open leading to failure once the oxidation damaged becomes too great to sustain the applied load. From the oxidation studies, a physics based oxidation model was developed and is used to study the oxidation kinetics and to simulate experimental tests. The experimental tests and the oxidation model provided a good basis for evaluating C/SiC materials which contain oxidation inhibitors. Particulates in the matrix and/or external coating were effective in sealing cracks due to the formation of solid oxides and glasses.