SILICON-CARBIDE INFILTRATION OF POROUS C-C COMPOSITES FOR IMPROVING OXIDATION RESISTANCE

This paper deals with the attempts made at LCTS to replace part of the carbon matrix of C-C composites by silicon carbide in order to improv e the oxidation resistance. Oxidation kinetics of C-C-SIC are presente d, as well as the incidence of oxidation on the degradation of the mic rostructure and the tensile strength of the composites. Modelling of t he oxidation kinetics allows prediction of mass losses as a function o f temperature, thickness of seal-coating, level of mechanical loading, and reactivity of the components toward oxygen. On the basis of this model, it is possible to determine a mechanism controlling the oxidati on kinetics, the degradation mode of the composite, and then the evolu tion of the tensile properties in oxidizing environments. Finally, fur ther improvement in the oxidation resistance of the C-C-SiC composites is discussed, based on a change in the thickness and nature of the Si C seal-coating.