Electro-Brush Plating from Deep Eutectic Solvent: A Case of Nanocrystalline Ni Coatings with Superior Mechanical Property and Corrosion Resistance

Electro-brush plating (EBP) procedure using deep eutectic solvent (DES) based electrolytes was adopted for the first time to prepare nanocrystalline Ni coatings on Fe substrates. The electro-brush plated Ni (EBP Ni) coating is featured as lower surface roughness, better bonding strength, and higher wear resistance in comparison with the traditional electroplated Ni (EP Ni) from the same DES electrolyte. Nanoindentation tests indicate the EBP Ni has a high ratio of hardness to Young's modulus (0.0551) and a high hardness of about 5.4 GPa, showing an optimum mechanical property. Moreover, the EBP Ni coating with a thickness of ∼3.6 μm exhibits an enhanced corrosion resistance over the EP Ni for protecting Fe substrate. The unique deposition dynamics at the electrode/DES interface during the EBP process is suggested as being responsible for the superior mechanical property and enhanced corrosion resistance of the EBP Ni coatings.