Effect of Gas-Dynamic Spraying Temperature on Diffusion and Transformations of Phase Composition and Microstructure During Formation of Coatings Based on Copper and Zinc

The process of formation, the structure, and the phase composition of coatings based on copper and zinc and deposited by cold gas-dynamic spraying are studied. It is shown that a multiphase structure is formed in the coating based on a solid solution of copper in zinc, a solid solution of zinc in copper and solid solutions based on electron compounds CuZn₃ and Cu₅Zn₈. At a low spraying temperature (270°C), the formation of the structure is mainly influenced by interboundary diffusion. The total diffusion rate is D_c = 0.15 × 10^–12 m²/sec. When the spraying temperature is increased to 360°C and higher values (450°C), the vacancy diffusion mechanism prevails. The diffusion rate increases to D_c = 0.56 × 10^–12 m²/sec, which is accompanied by an increase in the mass fraction of the transformation products. A model of formation of the multiphase gradient coating structure is suggested and the influence of the spraying parameters on the formation of the structure is discussed.