Effect of Expansion Ratio of Rectangular Nozzles on Spray Pattern of Copper Coatings in Cold Spraying

In the cold spray process, cross-sectional shape of the nozzle has a significant effect on spray pattern of coatings. There is a rectangular and a circular cross-sectional shapes on the cold spray nozzle. It has been reported that spray pattern of the rectangular spray nozzle is wider than that of the circular spray nozzle. Accordingly, rectangular nozzle is better efficiency than circular nozzle at spray a constant width. The goal of this investigation is to establish a design for the cold spray gun nozzle in order to gain a flatter the spray pattern of coatings. In this study, the computational fluid dynamics (CFD) and experiments investigated the effect of expansion ratio of rectangular nozzle on spray pattern of copper coatings in cold spraying. We made converging-diverging rectangular nozzle with expansion ratio of 6.1, 11.2 and 15.0, to compare with the circular nozzle.