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.