Effects of multi-layer graphene on the fracture toughness and wear resistance of WC-11Co cemented carbide

Abstract

The effects of multi-layer graphene (MLG) on the properties of tungsten carbide-11 cobalt (WC-11Co) cemented carbides were studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD) and other methods. The results show that when the MLG content is 0.1 wt%, the density, hardness and fracture toughness are 3%, 14.5% and 71.8% higher, respectively, compared with the sample without MLG. Bridging and deflection of cracks by MLG improve the fracture toughness of WC-11Co. In addition, MLG inhibits the transformation of the Co phase into Co3C during the sintering process and makes Co phase maintain FCC structure at room temperature, thus enhancing the fracture toughness of the matrix. MLG prevent the matrix from generating W3Co3C and Co3C, thus improving wear resistance. Furthermore, MLG improves the thermal conductivity of cemented carbide and greatly reduces the degree of oxidative wear of the matrix during friction tests. The wear volume of the sample with 0.1 wt% MLG is 98% smaller than that of the sample without MLG, but its mean friction coefficient is 8.8% higher during stable stage. It is because the solid lubricating effect of the wear debris is greater than that of the MLG after 900s.