Microstructure and mechanical properties of B4C densified by spark plasma sintering with Si as a sintering aid

Abstract Dense B 4 C compacts were fabricated by spark plasma sintering (SPS) technique in the presence of Si as a sintering aid. The densification behavior and mechanical properties of B 4 C at 1700 °C for 7 min with additions of Si up to 10 wt% were studied. The sinterability was improved by adding small amount of Si due to the formation of liquid Si during sintering and then molten Si reacted with free carbon supplied by B 4 C. The relative density, Vickers hardness and flexural strength of the B 4 C/SiC composite prepared from 8 wt% Si reached 99.73±0.07%, 36.72±1.55 GPa, and 612±10 MPa, respectively. The addition of Si as a sintering aid to the B 4 C was found to alter the fracture mode from purely transgranular to a mixture of transgranular and intergranular fracture.