Enhanced mechanical properties of boron carbide ceramics prepared by spark plasma sintering with boron nitride nanosheets addition

Abstract

Boron carbide (B4C) ceramics with enhanced mechanical properties have been fabricated with boron nitride nanosheets (BNNSs, 1.5–5 wt%) as reinforcement via spark plasma sintering. The densification temperature of the B4C ceramic containing 3 wt% BNNSs (B4C-3 %BNNSs) was reduced to 1480–1700 °C, approximately 100 ℃ lower than the pure B4C ceramic. The B4C-3 %BNNSs composites with a density of 98.9 % and associated Vickers hardness of 34.4 GPa, flexural strength of 654 MPa, and fracture toughness of 4.86 MPa·m1/2 that represent a respective increased by 1.1 GPa (3.3 %), 178 MPa (37.4 %) and 1.57 MPa·m1/2 (47.7 %) relative to pure B4C. The reinforcement mechanisms due to BNNSs combined with B4C involves a synergistic effect of the decrease in densification temperature where the BNNSs promote B4C grain rearrangement, B4C twin grain boundaries, and BNNSs pull-out, crack branching and crack deflection effects.