Direct preparation of nanostructured Ni coatings on aluminium alloy 6061 by cathode plasma electrolytic deposition

A pure nanostructured Ni coating was directly prepared by continuous cathode plasma electrolytic deposition (CPED) on aluminium alloy 6061. The microstructures and compositions of the as-deposited coatings were studied by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD), followed by hardness and adhesion evaluations. Due to the plasma micro-arc and rapid quench, the Ni coatings prepared by CPED exhibit typically molten morphologies with nanocrystalline structures, which are capable of increasing the hardness values of the coatings. In addition, the adhesion abilities of the as-prepared coatings could be enhanced by metallurgical bonding between the coatings and the substrate. Moreover, the continuous CPED method is a high-efficiency approach to fabricate coatings with large areas. •A pure nanostructured Ni coating was directly prepared by continuous CPED.•The nanostructure of CPED-prepared coating can substantially increase hardness.•The adhesion of the Ni coating is enhanced by metallurgical bonding.•The continuous CPED method is a high-efficiency approach to fabricate coatings.