Influence of fiber surface properties of SiCf/SiC composites on the interfacial debonding behavior

SiC fiber-reinforced SiC matrix composites (SiCf/SiC) containing BN interphase were fabricated via CVI and MI. For fiber-treated SiCf/SiC composites, cracks that initiate in the matrix tend to deflect between the fiber and the BN interphase when it reaches the fiber/matrix region, and the interface debonding and sliding occurs between the BN interphase and the matrix when fibers are pulled out. The mechanical properties of fiber-treated SiCf/SiC composites are significantly improved. The roughness and chemical properties are analyzed for the treated and as-received SiC fibers. The relationship between the surface chemical composition and roughness of fibers and the fiber/interphase adhesion force is discussed. The composites prepared from the treated fibers are confirmed to have stronger fiber/interphase adhesion force, which is caused by the improvement of surface roughness, the decrease of SiO2 on the fiber surface, and the interinfiltration of BN and excess C on the treated fiber surface.