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

Dense B4C 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 B4C at 1700 degrees 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 B4C. The relative density, Vickers hardness and flexural strength of the B4C/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 B4C was found to alter the fracture mode from purely transgranular to a mixture of transgranular and intergranular fracture. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.