Temperature-dependent oxidation kinetics and mechanical properties degradation of C_f/ZrB₂-SiC composites

The oxidation kinetics and microstructures evolution of C_f/ZrB₂-SiC composites are investigated by experimental characterizations. An empirical model containing multi-reaction systems is further established for predicting the specimen mass evolution during isothermal oxidantion. Based on the morphological observations and in-situ tensile responses, three oxidation mechanisms of carbon phase controlled by reaction and diffusion kinetic are categorized as uniform, non-uniform and superficial oxidation. The relationship between fracture modes and internal fibers microstructures indicates that the structural origin of the fracture mode transition is the toughening mechanism transition of fibers on the ceramics matrix induced by oxidative damage.