Effect of spraying parameters on surface roughness, deposition efficiency, and microstructure of electric arc sprayed brass coating

Abstract

Thermal, chemical, and metallurgical surface treatment techniques are being applied to give materials the desirable properties for numerous applications in service. Nowadays, electric arc spraying of copper alloys has gained importance in surface engineering owing to their excellent mechanical properties. However, electric arc sprayed metallic coating usually has high coating roughness and low deposition efficiency upon adherence to the substrate. In this article, the brass coating was deposited onto a mild steel substrate using a twin wire arc spraying technique. The spraying parameters current, voltage, and spray off distance were varied during the deposition process. To gain an understanding, the effect of these spraying parameters on the characteristics of the coating was investigated in terms of its surface roughness, deposition efficiency, and microstructure. The primary purpose of this research is to optimize the process in terms of coating roughness and deposition efficiency. Based on the results obtained, it was observed that an increase in voltage and spray off distance resulted in an increase in coating roughness, whilst an increase in current resulted in a decrease in coating roughness. Deposition efficiency was also greatly affected by the process parameters and decreased significantly with the longer spray off distance. Furthermore, the deposition efficiency increased with the decrease in surface roughness and vice versa. The best results in terms of low coating roughness, high deposition efficiency, and optimized microstructure were found at 24V, 240A, and 100 mm. The use of small diameter feedstock, supersonic nozzle incorporated in equipment, better surface preparation, and optimized process parameters gave better results as compared to the previous study in the field of electric arc spray coating.