Enhancing thermal properties of W/Cu composites

Abstract

Two alternative techniques based on coating and chemical co-synthesis for making W/Cu powder composite with improved thermal properties were evaluated. The properties of W/Cu synthesised by these techniques were compared with mechanically blended powders. The distribution of copper in the consolidated samples was analysed using an optical microscope. The influence of copper distribution on the properties, such as thermal conductivity and coefficient of thermal expansion, was evaluated. The thermal conductivity of a coated sample was the highest (190 W m⁻¹ K⁻¹) when compared with that of co-synthesised (140 W m⁻¹ K⁻¹) and ball milled (165 W m⁻¹ K⁻¹) specimens. Although the co-synthesised sample has the better distribution of copper in the tungsten matrix, the poor densification was attributed to the lack of formation of continuity among copper phase. The coated sample has a lower thermal expansion coefficient (4·7 ppm/K) than that of co-synthesised sample (6·8 ppm/K).