Synergistic effects of TiB2 and graphene nanoplatelets on the mechanical and electrical properties of B4C ceramic

Abstract

Monolithic B4C, B4C–TiB2, and B4C–TiB2–graphene nanoplatelets (GNPs) were fabricated by hot pressing (HP) at 1900 °C for 1 h under an axial pressure of 30 MPa. The microstructures and mechanical and electrical properties of the B4C composites were investigated. The results show that the GNPs are distributed homogeneously in B4C-based ceramic composites. Compared with monolithic B4C, the TiB2–GNPs-containing B4C composite exhibits an approximately 68 % increase in flexural strength and a 169 % increase in fracture toughness due to the synergistic effects of TiB2 particles and GNPs. The toughening mechanisms mainly include TiB2 crack deflection, crack branching, transgranular fracture and GNPs crack deflection, crack bridging, and GNPs pull-out. Additionally, the electrical conductivity of the B4C composite reinforced with dual fillers is three orders of magnitude higher than that of monolithic B4C due to the establishment of a conductive network. The addition of GNPs can efficiently connect the isolated conductive TiB2 particles in the B4C matrix and provides an additional channel for electron migration.