Microstructural development and factors affecting the performance of a reaction-bonded silicon carbide composite

Due to its near net-shape forming characteristic, reaction-bonded silicon carbide (RBSC) is an ideal sintering material to prepare complicated structural SiC-based ceramics when combined with selective laser sintering (SLS). With this understanding, various factors affecting RBSC composites and the performance control methods were analyzed in this work. By studying the microstructural development and reaction mechanism during the reaction-bonded process, the main factor affecting the performance was found to be the carbon density of SiC/C preform. The residual silicon content decreased with the increase in the carbon density of preform, thereby improving the performance. When the carbon density of preform exceeded the maximum value, some unreacted carbon existed in the sintered body, resulting in the degradation of performance. In order to break the limit of maximum carbon density of the preform, two effective approaches, namely the slow-release carbon source and new-style structure capillary channel were proposed in this work.