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 (B 4 C, TiC and Si powders) on the characteristics of both TiB 2 –SiC composite powders and ceramics. Results show that the size of B 4 C and Si particles hardly affects the size of TiB 2 and SiC particles because B 4 C is decomposed and consumed during the formation of TiB 2 , 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 TiB 2 particles and TiB 2 grains in the composite ceramics because TiC particles serve as templates to form TiB 2 particles. Consequently, the microstructure and mechanical properties of the TiB 2 –SiC composite ceramics are affected. The TiB 2 –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). [ABSTRACT FROM AUTHOR]