Microstructures of a carbon-fiber-reinforced silicon-carbide composite produced by precursor pyrolysis and hot pressing

Abstract The microstructures of a 1D-C f /SiC composite, prepared by polymeric precursor pyrolysis and hot pressing, with polycarbosilane (PCS) as precursor and AlN–Y 2 O 3 as sintering additives, were investigated by using XRD, HRTEM, and SEM. During sintering, Y 2 O 3 reacted with the pyrolysis products of the PCS and the oxides on the surfaces of the AlN and SiC grains, forming a liquid-phase which assisted in the densification. Owing to the formation of a carbon-rich fiber/matrix interphase with a certain number of SiC–AlN solid solution grains, a desirable level of fiber/matrix interfacial bonding could be obtained which facilitated the debonding and pull-out of the fibers. The composite therefore exhibited better mechanical properties and the average flexural strength and fracture toughness values were 691.6 MPa and 20.7 MPa m 1/2 , respectively.