Fabrication of Graded WC-Co Cemented Carbides by a Lamination Method

WC-Co tapes with different Co contents were prepared by rolling the mixtures of WC-Co powders and polymer binders, and layered WC-Co green compacts with discontinuous distribution of Co contents were obtained by laminating the green WC-Co tapes together. After burning off the binders and other organic composition in H2 atmosphere, the green compacts were sintered in vacuum. Microstructure of both the green and the sintered tapes were observed by scanning electron microscope. An electron probe microanalyser was used to measure the linear distribution of Co element in the layered WC-Co cemented carbides. Sintering densification and mechanical property of the multilayered WC-Co alloys were also investigated and compared with those of conventional WC-Co alloys with nominal Co contents of 8% and 12%, respectively. It was shown that by controlling sintering temperature and time, a continuous graded distribution of Co composition can be realized in the laminated WC-Co alloys, with more Co-rich phase in the original high Co content side (12%). Furthermore, the graded WC-Co cemented carbides can realize a combination of high hardness and high strength.