Thermodynamic modeling of phase equilibria in the WO3-Zn system

There are no alloys ill the W-Zn binary system. The combustion process ill the WO3-Zn powder mixture gives mainly metallic tungsten and zinc oxide. The ZnO in the product can be easily leached (e..g.. with HCl), so that front stoichiometric quantities of reagents. one call obtain W powder of good purity. Here we investigated the phase equilibria for the WO3-Zn system in the temperature range of 900-1500 K. The inert component (Ar-) was introduced into the system to change the pressure within the range of 0.1-0.5 MPa. When the pressure is constant, the quantity of tungsten dioxide ill the equilibrium mixture of components increases with rise in temperature, while the fraction of tile zinc oxide decreases, The fraction of metallic tungsten in the mixture also decreases with temperature increase and becomes near zero at 1500 K and 0.1 MPa. Up to 1100 K. tile output of tungsten is close to the limiting (stoichiometric) value in tile whole considered pressure range (0.1-0.5 Mpa).