Study of through-thickness notch effects on high temperature fracture behavior of a SiC/glass-ceramic composite

Tensile testing, microdebonding and light and scanning electron microscopy techniques were utilized to investigate through-thickness notch effects on high temperature fracture behavior of a SiC/calcium-aluminosilicate composite. Fracture mechanism of the composite changes from notch insensitive at room temperature to notch sensitive at elevated temperatures. This is due to increased fiber-matrix bond strength caused by oxidation effects at interfaces exposed to the oxidative environment. Concentration of the stress at the notch tip increases the high temperature embrittlement effect on the composite. Stress concentration and bending effects at the notch tip result in growth of the notch through fibers in planar fashion covering the entire fracture surface, contrary to the case of the unnotched composite for which two distinct fracture surface regions are observed as planar embrittlement zones at the periphery and fibrous at the center.