G0510401 A Study on the Mixing Temperature of Process/Carrier Gases in Cold Spray

Abstract

Cold spray can make a coating on a wide variety of mechanical parts by spraying solid particles accelerated by a high-speed gas flow through a converging-diverging nozzle. Experimentally it is well known that the particles start to deposit on the substrate when the impact velocity exceeds material-dependent threshold value. Therefore, the particle velocity at impact is important in the cold spray. Particle velocity is dependent on various parameters. One of parameters is the total gas temperature. The particle velocity is dependent on the total gas temperature, however, it decreases due to heat transfer from the gas to the spray particles injected in the nozzle. In this study, the decrease in the total gas temperature due to heat transfer from the gas to the spray particles is estimated using a simple model for two different spray materials. The analysis was performed using helium and nitrogen as working gas.