Effects of Ni addition on mechanical properties and corrosion behaviors of coarse-grained WC-10(Co, Ni) cemented carbides

Abstract

The effects of the Ni content on the mechanical properties and corrosion behavior of coarse-grained WC-10Co cemented carbide, with a grain size of 3.5 μm, were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical measurements, and mechanical property tests. The results indicate that the strength and toughness are improved with the addition of 2 wt% Ni without sacrificing hardness. Furthermore, the existence of Ni can decrease the corrosion current density (icorr) of WC-10Co cemented carbide in both 0.1 M HCl and 0.1 M NaOH solutions. The SEM and XPS results reveal that only a minor amount of WO3 formed in the corroded surface in HCl solution. The corrosion behavior was determined by the dissolution of the binder phase, and Ni can develop the charge-change resistance (Rct). Contrarily, the Co binder phase were oxidized to a dense passive film (Co(OH)2 and Co3O4) in NaOH solution, and the addition of Ni was conducive to the enhancement of the diffusion resistance (Rf). This may give insights into adding an appropriate Ni content in coarse-grained WC-Co cemented carbide, in which the wear and corrosion of the components coexist.