Development of continuous SiC fiber-reinforced reaction sintered SiC matrix composite

A dense silicon carbide matrix composite reinforced by Hi-Nicalon fibers with boron nitride coating was fabricated by slurry impregnation and subsequent reaction sintering process. Hi-Nicalon fibers were not stable in contact with molten silicon. Accordingly the effect of the fiber coating structure and the infiltrating metal composition on the mechanical properties of the composite was investigated. Selecting a boron nitride and silicon carbide dual coating structure and a boron-doped silicon as the infiltrating metal, a ceramic matrix composite with excellent fracture energy could be newly developed. The microstructure and the bending strength at room and high temperatures were also evaluated. Optimized composite showed cumulative failure mode both at room temperature and at 1573 K. The failure behavior kept this cumulative fracture mode even after oxidation at 1573 K for 360 ks. Good oxidation resistance was thought to be caused by the presence of the dense SiC matrix.