Effect of sintering additives on microstructures and mechanical properties of short-carbon-fiber-reinforced SiC composites prepared by precursor pyrolysis–hot pressing

Short-carbon-fiber-reinforced SiC composites were prepared by precursor pyrolysis–hot pressing with MgO–Al2O3–Y2O3 as sintering additives. The effects of the amount of sintering additives on microstructure and mechanical properties of the composites were investigated. The results showed that the composites could be densified at a relatively low temperature of 1800 °C via the liquid-phase sintering mechanism and the composite density and mechanical properties improved with the amount of additives. The amorphous interphase in the composites with more additive content, not only avoided the direct contact of the fibers with matrix, but also improved the fiber–matrix bonding. It proved that the fiber–matrix interphase characteristics played a key role in controlling mechanical properties of the composites.