Preparation and properties of Ni-coated WC powder and highly impact resistant and corrosion resistant WC-Ni cemented carbides
Fanlu Min, Songbai Yu, Sheng WANG, Zhanhu Yao, Jacques Noudem, Si-jin LIU, Jian-feng ZHANG
Abstract
WC powders were uniformly coated by Ni nanoparticles through a combined chemical co-precipitation and subsequent high temperature hydrogen reduction strategy (abbreviated as CM-WCN), and then were consolidated by vacuum sintering at 1450 °C for 1 h to obtain WC-Ni cemented carbides. The microstructure and properties of the as-consolidated CM-WCN were investigated. The average grain size of WC in the consolidated CM-WCN was calculated to be in the range of 3.0–3.8 μm and only few pores were observed. A relative density of 99.6%, hardness of HRA 86.5 and bending strength of 1860 MPa were obtained for the CM-WCN-10wt.%Ni, and the highest impact toughness of 6.17 J/cm2 was obtained for the CM-WCN-12wt.%Ni, surpassing those of the hand mixed WC-Ni (HM-WCN) cemented carbides examined in this study and the other similar materials in the literature. CM-WCN cemented carbides possess excellent mechanical properties, due to their highly uniform structure and low porosity that could be ascribed to the intergranular-dominated fracture mode accompanied by a large number of plastic deformation tears of the bonding phase. In addition, the corrosion resistance of CM-WCN was superior to that of HM-WCN at the Ni content of 6-12 wt.%.