Thermal and Electrical Properties of Copper Coatings Produced by Cold Spraying

Abstract

A cold spray process has been developed for dense and clean and tightly bonded coatings in contract with other established thermal spray processes. The cold sprayed copper is particularly well suited for metallic coatings, such as electric conductor and heat-sink. However, the thermal and electrical properties of copper coatings formed by the cold spray process have not always been clarified. Four kinds of free-standing copper specimens, which were formed by the cold spray process and an atmospheric plasma spray process, were machined from the thick coatings and were used for measuring the thermal conductivity, specific heat and electrical resistivity etc. The experimental results suggested that the porosity and oxide content had important effects on the thermal and electrical properties. Namely, high thermal conductivity and the low electrical resistivity of coatings could be obtained from the cold spray process, because of the low porosity and the low oxide content. Also, it was confirmed that the thermal conductivity of cold sprayed copper could be improved at high temperature by the sintering effect.