Effect of powder alloy composition on the microstructure and properties of kinetic sprayed Cu-Ga based coating materials

Abstract

This study attempted to manufacture Cu-Ga coating materials via the kinetic spray process and examined the effect of powder alloy composition on the microstructure and properties of the kinetic sprayed Cu-Ga based coating materials. Cu-15 at%Ga, Cu-20 at%Ga, and Cu-30 at%Ga powders were prepared and used. Annealing heat treatments were conducted at 200 °C~800 °C. The results showed that the coating layers could be manufactured with Cu-15 at%Ga and Cu-20 at%Ga powders via the kinetic spray process, except for Cu- 30 at%Ga. A single phase of pure Cu was observed in the Cu-15 at%Ga coating layer and Cu and Cu₃Ga phases in the Cu-20 at%Ga coating layer. A small amount of Ga₂O₃ was also detected between deposited particles in both coating layers. It was difficult to obtain the coating layer due to the shattering of powders during the kinetic spraying with Cu-30 at%Ga powder, which is made up of a variety of inter-metallic compounds. Porosity and hardness decreased as the annealing temperature increased, and porosity decreased into 0.48% (Cu-15 at%Ga), 0.74%(Cu-20 at%Ga) at 800 °C. Annealing heat treatment appeared to be effective in enhancing the density of the coating layers without generating a new phase. This study also considered to suggest the optimal alloy composition of kinetic sprayed Cu-Ga based coating material for sputtering target.