Influence of powder injection point position on efficiency of powder preheating in cold spray: Numerical study

• Efficiency of additional powder preheating in cold spray is numerically studied.
• Two types of powder injection (subsonic and supersonic) are considered.
• It was shown that preheating efficiency depends on the type of injection.

Cold spray is a material deposition technique based on the high velocity particle–substrate impact. The last researches in this field show that efficiency of deposition depends not only on the particle impact velocity but also on the impact temperature. In order to control the particle impact temperature, a special powder preheater installed between the powder feeder and the nozzle could be applied. In the current paper, an influence of powder preheating on the particle impact parameters is numerically studied. Two cases with powder injection to subsonic and supersonic regions of the nozzle are considered. It is shown that artificially preheated 10–50 μm copper particles axially injected to the supersonic region of the nozzle have higher impact temperature than the particles injected to the nozzle prechamber. This effect could be explained by the dependence of duration and intensity of gas–particle heat exchange on the location of powder injection point. It was also shown that in the case of powder injection to supersonic zone, the application of powder preheating could shift the particle impact parameters towards the deposition window without increasing the working gas stagnation temperature.