Evaluation of fracture characteristics for SiC/SiC composites under high temperature condition by acoustic emission method

The temperature dependency of mechanical properties on woven-cloth SiC-fiber reinforced SIC composite materials, which were fabricated by injection molding method, was examined under slow speed(0.02mm/min) tensile test with Acoustic Emission(AE) method under various temperatures and atmosphere condition. Acoustic emission signal was detected by piezoelectric AE sensor in real time. It was found that the amplitude of AE signal was very important parameter to evaluate fracture mechanism such as matrix cracking debonding, delamination and fiber breaking etc.. SiC/SiC composite material had totally different fracture mechanism between room temperature and high testing temperature. The strength degradation of these composites at elevated temperature was turned out to be due to the formation of SiO2 and TiO2 oxide particles.