Leonid P. Dorfman

Consolidation of tungsten-coated copper composite powder

Powder metallurgy (P/M) methods have expanded in recent years to include net-shape fabrication of W-Cu components. Sintering of W-Cu compacts made from previous powders has led to low density and copper bleedout. This paper presents test results on the consolidation of a new powder containing particles composed of a tungsten-coated copper core. This powder effectively eliminates copper bleedout at sintering thereby making possible the net-shape manufacturing of parts. Sintered articles are characterized by microstructural homogeneity and properties comparable to those of infiltrated W-Cu composites.

Synthesis and hydrogen reduction of tungsten–copper composite oxides

Cupric tungstate (CuWO 4 ) can be synthesized at high rates of conversion from a variety of solid reactants. However, the fixed copper content in the metal phase of CuWO 4 limits its use as an oxide precursor for making W-Cu composite powders. This paper presents test results on synthesis of CuWO 4 -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.