Deposition potential effect on surface properties of Zn–Ni coatings

The electrodeposition of Ni–Zn alloy coatings at different deposition potentials from a sulphate bath was studied by means of chronoamperometry, anodic linear stripping voltammetry, X-ray diffraction and atomic force microscopy. Corrosion behaviour of Zn–Ni alloys in 3.5 wt-% NaCl solution was examined by anodic polarisation and electrochemical impedance spectroscopy. Results indicated that the nickel content in the deposit is enhanced with more negative deposition potential, where the average surface roughness decreased. Electrochemical measurements obtained by anodic polarisation and impedance spectroscopy revealed that Zn–Ni alloy coatings obtained at more negative potential present best corrosion resistance.