Effects of particle size of raw materials on the characteristics of TiB2–SiC composites fabricated from B4C, TiC and Si powders

Abstract

We studied the effects of particle size of raw materials (B4C, TiC and Si powders) on the characteristics of both TiB2–SiC composite powders and ceramics. Results show that the size of B4C and Si particles hardly affects the size of TiB2 and SiC particles because B4C is decomposed and consumed during the formation of TiB2, and Si is melted during the formation of SiC. The size of SiC particles is within the nano and submicron scale. However, the size of TiC particles determines the sizes of TiB2 particles and TiB2 grains in the composite ceramics because TiC particles serve as templates to form TiB2 particles. Consequently, the microstructure and mechanical properties of the TiB2–SiC composite ceramics are affected. The TiB2–SiC composites fabricated using nano-sized TiC powder possess smaller grain size, better dispersibility and more reasonable crack propagation path, thereby obtaining the optimal mechanical properties (Vickers hardness of 30.2 GPa, flexural strength of 732 MPa and fracture toughness of 7.37 MPa m1/2).