The active-to-passive oxidation transition mechanism and engineering prediction method of C/SiC composites

Abstract

This paper studied the active-to-passive oxidative mechanism of C/SiC composite under high temperature and oxidative conditions. An analytic model and computational method were established based on the process of gas diffusion in boundary layer and the equilibrium relations in surface chemical reactions. Simultaneously, an engineering equation to predict the oxygen partial pressure of active-to-passive transition was derived under the specific temperature zone. The results indicated that the active-to-passive oxidation transition of C/SiC is closely related to the composition of the material. At certain temperature and oxygen partial pressure conditions, the composite with high carbon content is prone to cause active oxidation which is negative to the oxidation resistance of the material.