Enhanced toughness and strength of boron carbide ceramics with reduced graphene oxide fabricated by hot pressing

Abstract

Boron carbide (B4C) hybrids with different contents of graphene oxide (GO) were prepared by a heterogeneous co-precipitation method using cetyltrimethyl ammonium bromide (CTAB) as the cationic surfactant. The as-obtained mixtures were further hot-pressed at 1950 °C for 60 min under 30 MPa, by which B4C–reduced GO (rGO) composites were fabricated. It was found that the addition of only 0.5 wt% rGO could alter the predominance of trans-granular fracture in monolithic B4C ceramic material to mixed trans-granular and inter-granular modes in B4C–rGO composites. The flexural strength and fracture toughness of the B4C–2 wt% rGO were increased by 31% (from 350 to 455 MPa) and 83% (from 3.20 to 5.85 MPa·m1/2), respectively, compared with those of pure B4C. The improved mechanical properties are attributed to the mechanisms of pull-out and bridging of rGO and crack deflection, as evidenced by microstructural observations. The energy dissipation in the present B4C–rGO composites was further verified using two micromechanical models.