Coating recession effects in ceramic composite strength

BN fiber coatings in SiC-SiC composites are vulnerable to oxidation and volatilization at elevated temperature the presence of water vapor. These processes lead coating recession composite interior with fronts starting from matrix cracks proceeding axially along fibers. In some operational domains, main effect is de-couple fibers matrix, precluding load transfer that would otherwise occur through frictional sliding. Here we present a modelling framework address effects on strength. The built upon characteristic strengths lengths govern fragmentation during tensile loading. Four dominant behavioral domains identified analyzed. Recession causes shifts domain boundaries reductions Variations degraded strength extent interpreted terms stress rupture plots. regime where leads time-dependent fracture, response defined by two strengths: (i) pristine (governed situ bundle properties) (ii) threshold below which failure not predicted an equivalent absence matrix). time scales set square ratio length crack spacing, latter governed combination distribution, interface sliding stress, content applied stress.