Ni electroplating on AZ91D Mg alloy using alkaline citric acid bath

Abstract

Abstract Electroplating of Ni on an AZ91D Mg alloy in alkaline citrate baths was studied. It was found that NiSO4 and citric acid form a soluble complex. Ni plating with a smooth surface was obtained from the bath containing 0.55 mol dm −3 of nickel sulfate, 0.28–0.55 mol dm −3 of citric acid, and 0.88 mol dm −3 of aqueous ammonia at pH 10. The cathodic current efficiency decreased with increasing cathodic current density, which is beneficial for obtaining a uniform Ni-plating layer on components with complex shapes. The addition of KCl and saccharin sodium salt to the bath improved anodic dissolution and reduced the stress in the plating layer, respectively. With zinc replacement treatment, an adhesive Ni layer formed on the AZ91D Mg alloy.