Oxidation-resistant carbon-fiber-reinforced ceramic-matrix composites

A multilayer Si-B-C ceramic matrix has been developed to improve the oxidat ion resistance and the lifetime in an oxygen environment of carbon-fiber-re inforced ceramic-matrix composites. This concept has been applied to a mult idirectional fibrous carbon preform. The paper deals with the processing, t he mechanical behaviour and the oxidation resistance of a carbon-fiber-rein forced multilayer ceramic-matrix composite. The efficiency of this matrix i s compared to that of the classical anti-oxidation systems based on an exte rnal coating usually employed to reduce the oxygen permeation. The efficien cy of the oxidation protection of the multilayer ceramic matrix is still ev ident in spite of the complex architecture of the fibrous preform and the d amage of the matrix. The experimental results show that a strong improvemen t in the lifetime of such composites under thermomechanical loading and in an oxygen environment is obtained when a multilayer matrix is used to prote ct the carbon reinforcement against oxidation. (C) 1999 Elsevier Science Lt d. All rights reserved.