Performance optimization of complicated structural SiC/Si composite ceramics prepared by selective laser sintering

Combining reaction-bonded (RB) process and selective laser sintering (SLS) method is an effective approach to prepare ceramic components with complex shapes. The purpose of this paper is to find efficient ways to improve the performance of SiC/Si composites prepared by SLS/RB technologies. Effects of epoxy resin binder on the performance and microstructure of preforms and sintered bodies were studied first. Then, based on the above results, graphite with low reactivity was used as an alternative slow-release carbon source to promote sintering densification process and improve the carbon density of preforms. When the added amount of graphite increased, clusters of nanometer-sized SiC grains formed and the silicon phase transformed into pieces, which reduced the content and dimension of silicon phase. Furthermore, by applying a two-step sintering method, the residual silicon content of SiC/Si composites decreased further and the flexural strength at high temperatures increased.