Effects of CVD SiBCN interphases on mechanical and dielectric properties of SiCf/SiC composites fabricated via a PIP process

SiBCN coatings were successfully prepared on KD-II SiC fibers via a chemical vapor deposition (CVD) process utilizing borazine and liquid polycarbosilane as precursors. Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) indicated the coating contained B–N, Si–C, C–C and Si–N bonds. Effects of the CVD SiBCN interphases on mechanical and dielectric properties of SiCf/SiC composites fabricated via a PIP process were investigated. The results showed that the composites with CVD SiBCN interphases exhibited an obvious toughened fracture behavior, and the flexural strength was about 2.25 times than that of the composites without SiBCN interphases. The composites containing SiBCN interphases had a higher strength retention ratio than that containing BN interphases. Furthermore, SiBCN interphases improved the fracture strength evidently, but hardly had influence on the dielectric properties of the SiCf/SiC composites.