Microstructures of short-carbon-fiber-reinforced SiC composites prepared by hot-pressing

Microstructures of short-carbon-fiber-reinforced silicon carbide composites, prepared by hot-pressing with MgO-Al₂O₃-Y₂O₃ as sintering additives, were investigated by means of X-ray diffractometry, scanning electron microscopy, and transmission electron microscopy. The results showed that the composites could be densified at a relatively low temperature of 1800 °C via the liquid-phase-sintering mechanism. The amorphous interphase in the composites not only avoided the direct contact of the fibers with the matrix, but also improved the fiber/matrix bonding, so they could improve the densification of the composites and avoid the degeneration of the carbon fiber. The nano silicon carbide derived from polycarbosilane, could play a role of improving the relative density of the composites.