Fabrication and characterization of low pressure cold sprayed copper coatings

Abstract

Cold spray has attracted a great deal of attention for fabrication of thick, high purity metallic coatings. In cold spray, metal particles are accelerated by process gas with solid phase and deposited onto substrate or previously deposited coating. In order to increase the particle velocity to deposit, harder metal materials, the process gas pressure need to be higher. However, using high gas pressure needs large facility and much gas consumption. In this study, the availability of low pressure cold spray upon fabrication of copper coatings was examined. Copper particles were sprayed with changing process gas temperature and pressure which, was less than. 1 MPa. It was effective to raise the gas temperature to enhance the deposition efficiency. It was possible to fabricate copper coatings with high deposition efficiency with controlling the gas temperature and pressure by low pressure cold spraying. The optimal particle size of copper powder was determined empirically for low pressure cold spraying. The hardness of the coatings did not depend on the porosity of the coatings, but. depended on the process gas temperature. Process gas temperature affected not only deposition efficiency but. also the characteristics of the coatings such as electrical conductivity.