Preparation of tungsten powder by the combustion of CaWO4/Mg

Tungsten powder was prepared by a Self-Propagating High-Temperature Synthesis(SHS) Process of a CaWO4- Mg mixture. Mg vapor was discovered to significantly affect such combustion parameters as the combustion temperature(T-c), the combustion velocity(U), the relative mass change(Delta m) and the relative elongation(Delta h) of the sample. These effects could be reduced by decreasing the internal Ar pressure, sample density and reducing agent content. The oxygen content in tungsten was decreased by using 5% excess Mg; the carbon content was diminished when the combustion process occurred under P-Ar=0.1 MPa. The MgO and CaO in the product was leached with an HCl solution. Such parameters as combustion temperature(T-c), U, Delta m, and milling time(tau) were found to affect the tungsten particle size and morphology.