Fine and high-performance B6.5C-TiB2-SiC-BN composite fabricated by reactive hot pressing via TiCN–B–Si mixture

Abstract

In this study, B6.5C-TiB2-SiC-BN composite was fabricated via reactive hot pressing from a powder mixture of TiCN, B, and Si. The reaction process of the powder mixture was investigated by heat treatment at elevated temperatures. The as-reacted powder products possessed a core-shell structure of TiB2 surrounded by h-BN. During densification, the h-BN in this structure acts as a diffusion channel and lubricant, which promoted the densification process. The extremely small size, fresh surface of in-situ formed phases, and uniform dispersion in synthesized powders also contributed to sintering. The designed reactive hot-pressing sintering effectively resolves the difficulty of obtaining uniformly-dispersed BN. The obtained bulk B6.5C-TiB2-SiC-BN composite ceramic shows high relative density (98.8%) and good comprehensive mechanical properties including hardness, bending strength, and fracture toughness of 19.6 GPa, 801 MPa, and 5.31 MPa m1/2, respectively.