Influence of Spray Parameters on the quality of low-pressure Cold Sprayed WC-Ni Coatings
Abstract
Considering the various parameters involved in cold spray and the need for optimizing cold spray processes, a statistical approach for optimization can prove to be greatly useful. In this study, a 33 full factorial design was used to analyze the effects of spray parameters on the thickness, hardness, and surface porosity of low-pressure cold-sprayed WC-17Ni coatings. The spray parameters included in the design were the powder feed rate, gas temperature, and the nozzle to substrate stand-off distance. It was found that the feed rate, stand-off distance, and the interaction between feed rate and stand-off distance were the most significant parameters that affected the coating thickness, porosity and hardness respectively. An optimization study was also performed to maximize the coating thickness and hardness while minimizing the surface porosity. The optimal spray parameters (OSP) were found to be a feed rate of 23.7 g/min, 500℃ for the carrier gas temperature and 10 mm for the stand-off distance that yielded a coating that was 1.22 ± 0.31 mm thick, with a hardness and surface porosity of 365 ± 8 HV and 6.7 ± 0.6%, respectively. The results suggest that variation of the selected parameters produce statistically significant effects on the coating quality.