Graphene nanosheets toughened TiB2-based ceramic tool material by spark plasma sintering

One kind of TiB2/TiC composite ceramic tool material toughened by graphene nanosheets was fabricated by spark plasma sintering. Effects of graphene nanosheets on microstructure, mechanical properties and toughening mechanisms were investigated. The results indicated that TiB2/TiC with 0.1 wt% graphene nanosheets sintered at 1800 degrees C with the holding time of 5 min obtained full densification and optimal mechanical properties. Its fracture toughness and Vickers hardness were 7.9 +/- 1.2 MPa m(1/2) and 20.0 +/- 0.7 GPa, respectively. Excess graphene nanosheets had no effects to toughness improvement. Fracture toughness was increased by 31.7% in comparison with the TiB2/TiC without graphene nanosheets. Toughness enhancement mainly benefited from crack bridging, also slip-stick effect of graphene made it hard to detach and effectively restrained crack extension.