Effect of h‐BN addition on friction and wear properties of C/C‐SiC composites fabricated by LSI

Hexagonal boron nitride (h‐BN) has excellent oxidation resistance, self‐healing function, and self‐lubricating properties, which can significantly improve the oxidation resistance of C/C‐SiC composites in low or medium temperature condition and affect their tribological properties and mechanisms. In this work, C/C‐SiC and C/C‐BN‐SiC composites were prepared by the same molding, carbonization and liquid silicon infiltration (LSI) process and the influences of h‐BN addition on their microstructure, tribological properties, and mechanisms were investigated. h‐BN addition can promote the formation of friction film and reduce the oxidation wear of the composites. Compared with C/C‐SiC composites, due to more lubricant components and different matrix structure, the C/C‐BN‐SiC composite shows lower wear rate (reduced by 53%) and moderate rather than too high coefficient of friction (CoF) and its CoF is less influenced by braking velocity. Moreover, the friction process is more stable and does not appear clamping stagnation phenomenon in high braking speed condition.