The role of SiCw in the microstructure and properties of WC-9Co gradient cemented carbide

Abstract

Powder metallurgy method was used to prepare WC-9Co gradient cemented carbide with various amounts of SiC whiskers (SiCw). The microstructure and properties of WC-9Co-SiCw gradient cemented carbide were studied. The thickness of gradient layer, metallographic structure and phase composition were investigated by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Vickers indenter, universal testing machine, tribometer and grazing incidence X-ray diffraction (GIXRD) were used to test the hardness, fracture toughness, bending strength, wear resistance and surface oxidation resistance of the specimens. According to the results, an appropriate addition of SiCw inhibited the growth of WC grains and facilitated the formation of the gradient layer. The relative density, hardness, fracture toughness and bending strength increased firstly and then decreased with the addition of SiCw. Furthermore, the wear resistance and surface oxidation resistance were improved by SiCw. However, an external addition of SiCw would adversely affect on sintering capability of WC-9Co-SiCw cemented carbide and decrease their comprehensive properties.