Preparation and properties of graphene/β-SiC-toughened ceramics

The brittleness of silicon carbide restricts its wide application. Graphene as a superior second-phase material can improve the toughness and brittleness of silicon carbide. In this article, a graphene/β-SiC ceramic material was prepared with 1–3 wt.% graphene added in β-SiC matrix via pressure-free sintering at 2120°C for 60 min. The effect of the graphene addition on the phase composition, bulk density, porosity, and mechanical properties of ceramic material was investigated. The results show that the bulk density of graphene/β-SiC ceramic material decreases, the porosity of openings increases, and the bending strength, hardness, as well as fracture toughness firstly increase and then decrease as graphene addition increases. Compared with β-SiC ceramic without graphene, the optimum properties of graphene/β-SiC ceramic with graphene addition of 1 wt.% (i.e. a fracture toughness of 5.07 MPa m1/2, bending strength of 410.84 MPa and hardness of 27.72 HV) can be obtained, which are increased by 35.56%, 13.35%, and 3.8%, respectively. The fracture morphology indicates that the crack deflection is the main mechanism of toughening β-SiC ceramic with graphene.