Electropolishing parameters optimization for enhanced performance of nickel coating electroplated on mild steel

The purpose of this work is to investigate the influence of electropolishing process on performance parameters of nickel coating electroplating on Q235A mild steel as substrate, including the surface roughness, thickness, elastic modulus and hardness. The contribution of magnetic stirring was first studied. On the basis of this, we explored the effect rules of electropolishing parameters on nickel coating using orthogonal test. The result showed that nickel coating became smoother and thicker by magnetic stirring in electropolishing process. The current density in electropolishing process significantly influenced the thickness, elastic modulus and hardness of Ni coating, while it showed little influence on the coating surface roughness. The above three parameters were also affected by polishing time and the temperature of polishing slurry. With the other condition remaining the same, elastic modulus and hardness of nickel coating reached their peaks after electropolishing with a current density of 30 A/dm2 in electrolyte at 65 °C for 15 min.