Size control of tungsten powder synthesized by self-propagating high temperature synthesis process

Tungsten powder was prepared by self-propagating high temperature synthesis (SHS) from a mixture of WO3 and Mg. The MgO in the product was leached wit h an HCl solution. The complete reduction of WO, required a 33% excess of m agnesium over the stoichiometric molar ratio Mg/WO3 of 3. The tungsten prod uct had a purity of 99.98%, which was higher than that of the reactants. Th e high purity resulted because the impurities in the reactants were volatil ized during the highly exothermic reaction and dissolved during leaching of the product. Size distribution and the shape of the tungsten particles pro duced was affected by compaction pressure on the green pellet. (C) 2000 Els evier Science Ltd.