Recovery of tungsten carbides to prepare the ultrafine WC-Co composite powder by two-step reduction process

A relatively low-cost, controllable particle size and eco-environmental recycling process for the oxidation and reduction of waste YG8 cemented carbides was achieved. The WC-Co composite powder has been synthesized by two-step reduction process. Reduction of WO3/CoWO4 in the hydrogen gas at 1073K is a feasible way for the production of W18O49 phase. Then the carbothermal reduction of the as-synthesized powder was carried out in Argon atmosphere mixed with ethanol gas, which was used as reductant as well as carbon source. Both the temperature and time in the present method of combing the higher reactivity of the precursor material and the better contact between the gas-solid reactants are apparently reduced as compared with the conventional methods. Based on the thermodynamic calculation and XRD analysis, the possible reactions involved in the carbothermal reduction were proposed. The influence of the holding time and carbon content were investigated. The two-step reduction process is a useful technique to prepare homogeneous WC-Co composite powder with particle size below 200nm at low temperature.