Properties of Silicon Carbide-Carbon Fiber Composites Prepared by Infiltrating Porous Carbon Fiber Composites with Liquid Silicon

Silicon carbide-carbon fiber composites have been prepared by partially Infiltrating porous carbon fiber composites with liquid silicon at a reaction temperature of $1670^{\circ}C$. Reaction between molten silicon and the fiber preform yielded silicon carbide-carbon fiber composites composed of aggregates of loosely bonded SiC crystallites of about 10$\mu\textrm{m}$ in size and preserved the appearance of a fiber. In addition, the SiC/C fiber composites had carbon fibers coated with a dense layer consisted of SiC particles of sizes smaller than 1$\mu\textrm{m}$. The physical and mechanical properties of SiC/C fiber composites were discussed in terms of infiltrated pore volume fraction of carbon preform occupied by liquid silicon at the beginning of reaction. Lower bending strength of the SiC/C fiber composites which had a heterogeneous structure in nature, was attributed to the disruption of geometric configuration of the original carbon fiber preform and the formation of the fibrous aggregates of the loosely bonded coarse SiC particles produced by solution-precipitation mechanism.