Modelling environmental effects on stress oxidation behaviour of carbon fibre reinforced ceramic matrix composites

A model has been developed for describing the stress oxidation strain evolution of carbon silicon carbide (C/SiC) composite in thermal, mechanical and chemical applied environments. A failure criterion is proposed to predict the lives of the C/SiC composites. The life is dominated by carbon phase oxidation if coat and matrix cracks are open to allow oxygen ingress. Crack opening displacement δ is considered as a key microstructural governing parameter and determined by the combination of mechanical and thermal expansionmismatch induced stresses, i.e. increased stresses widen the δ and increased temperatures narrow the δ. The proposed model gave correct and reliable prediction.