Preparation and mechanical properties of hard metals using graphene as carbon source

Normal carbon source black carbon was substituted by graphene which was dispersed in N-Methyl-2-pyrrolidone and nanocrystalline WC-Co composite powders were prepared using a short process in-situ reduction and carbonization reaction method. The results show that graphene as the carbon source could decrease the reaction temperature, and the particles of WC-Co composite powders are fine and the particle size distributes uniformly. Composite powders were consolidated through the spark plasma sintering system and the mean grain size of WC in WC-Co cemented carbides is about 290 nm. Vickers hardness and fracture toughness of the bulk is 13.877±0.131 GPa and 8.3±0.1 MPa·m^1/2, respectively. HRTEM images show that the grain boundaries of interfaces between WC/WC, WC/Co and WC/C are of low misfit.