Preparation and Mechanical Properties of SiC_f/SiC Composites

Silicon carbon fiber-reinforced SiC composites were prepared by precursor pyrolysis-hot pressing (PP-HP) and precursor impregnation-pyrolysis (PIP), respectively. The effect of fabrication methods on the microstructure and mechanical properties of the composites was investigated. It was found that the composites prepared by PP-HP exhibited brittle fracture behaviors though they were well densified, which was mainly ascribed to a strongly bonded fiber/matrix interface and the degradation of the fibers caused by higher processing temperature. On the contrary, the composite prepared by PIP showed tough fracture behaviors, which could be rationalized on the basis of a weakly bonded fiber/matrix interface as well as higher strength retention of the fibers. As a result, in comparison with the composites prepared by PP-HP, the composites prepared by PIP achieve better mechanical properties with a flexural strength of 703.6MPa and fracture toughness of 23.1Pa·m1/2.