Effect of voltage and spray-off distance of electric-arc spray technique on surface properties of nickel-chrome (Ni-Cr) coating developed on 304L stainless steel

Nickel-chrome coatings are widely used to improve surface properties and service life of engineering components made from different ferrous and non-ferrous alloys. Herein, an attempt has been made to investigate the impact of various voltages ranging from 26-30 V and spray-off distances ranging from 100-300 mm of electric-arc spray technique on the surface properties of Ni-Cr coating developed on 304L stainless steel. Thickness, porosity, surface morphology, surface roughness, and hardness of Ni-Cr coatings were determined to study the impact of deposition parameters. Coating deposition at 26 V exhibited the lowest porosity and the highest percentage of Cr nodules among all samples. The comparison study showed that coating deposit developed at 26 V and 100 mm spray-off distance has a maximum thickness, followed by coating developed at 30 V and 100 mm spray-off distance. This indicated that coating deposit developed at 100 mm spray-off distance results in thicker coatings. Maximum hardness was achieved at 30 V and 300 mm spray-off distance. The shorter spray-off distance revealed that coatings tend to be thicker and harder resulting in longer coating life.