Synthesis and hydrogen reduction of tungsten–copper composite oxides

Cupric tungstate (CuWO₄) can be synthesized at high rates of conversion from a variety of solid reactants. However, the fixed copper content in the metal phase of CuWO₄ limits its use as an oxide precursor for making W–Cu composite powders. This paper presents test results on synthesis of CuWO₄-based composite oxides with a variable content of copper in the metal phase (5–25.7%). Hydrogen reduction converts the oxides to W–Cu composite powders with a unique phase distribution: each individual particle consists of a tungsten phase and a copper phase in which the tungsten phase substantially encapsulates the copper phase. These powders, when pressed and sintered without activators, yield high-density parts with a very fine microstructure and high electrical and thermal conductivity.