SIZE CONTROL OF TUNGSTEN POWDER SYNTHESIZED BY SELF-PROPAGATING HIGH TEMPERATURE SYNTHESIS PROCESS

摘要

Tungsten powder was prepared by self-propagating high temperature synthe- sis (SHS) from a mixture of WO_3 and Mg. The MgO in the product was leached with an HCl solution. The complete reduction of WO_3 required a 33/100 excess of magnesium over the stoichiometric molar ratio Mg/WO_3 of3. The tungsten product had a purity of 99.98/100, which was higher than that of the reactants. The high purity resulted because the impurities in the reactants were volatilized during the highly exothermic reaction and dissolved during leach- ing of the product. Size distribution and the shape of the tungsten particles produced was affected by compaction pressure on the green pellet.