Program to Study the Oxidation of Carbon-Carbon Composites and Coatings on These Materials
Final rept. 15 Jul 1986-13 Jul 1989
PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
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The oxidation of carbon-carbon composites and coatings on these composites in oxygen at temperatures between 300 to 1400 C has been investigated. State-of-the art systems have been characterized prior to the oxidation studies by using optical and scanning electron microscopy. It has been determined that uncoated carbon-carbon composites cannot be used at temperatures above about 400 C for extended periods of time because of oxidation. Oxidation does occur at temperatures below 400 C but at very low rates. Boron has not been found to be an effective inhibitor for carbon-carbon oxidation. Water vapor increased the oxidation rate of these uncoated composites at temperatures below about 600 C. Oxidation products involving boron were removed from these composites at temperatures above 600 C when water vapor was present in the gas. Coatings were useful in protecting carbon-carbon composites from oxidation under isothermal test conditions but these coatings failed under cyclic conditions. The factors leading to the failure of coatings on carbon-carbon composites are described.
- Laminates and Composite Materials