Fabrication and Characterization of Low Pressure Cold Sprayed Copper Coatings

Abstract

1.PVD CVD 50% 90 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.

Fabrication of Titanium Dioxide Photocatalyst Coatings by Cold Spray

“…The maximum deposition efficiency was approximately 8% when the gas temperature was 673 K. Though the deposition efficiency was low, it was clarified that deposition of TiO 2 particles was enhanced with increase of the gas temperature. This phenomenon is similar to fabrication of copper coatings by cold spray 22) . In our equipment, …”

“…It indicates that the factors for the deposition of TiO 2 particles are almost same as that of Cu particles. It is expected that the deposition efficiency of TiO 2 particles can be controlled by not only the gas temperature but also the gas pressure 22) .…”