Synthesis and hydrogen reduction of tungsten–copper composite oxides

Abstract

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.