Anodic behaviour of amorphous NiP/tin multilayers in an acidic chloride solution

Abstract The anodic behaviour of electrodeposited NiP/Sn multilayers with submicron sublayers (0.1–0.5 μm) was tested in acidic (pH 4.5) NaCl aqueous solutions by voltammetric and potentiostatic techniques. A significant decrease of the passivation currents was observed especially when the Sn sublayers are very thin (∼0.1 μm). A compositional (EDX), structural (XRD) and morphological (SEM) characterisation of the electrodeposited multilayers was performed. Evidence for the formation of a protective layer at the NiP/Sn interface consisting of corrosion products of both NiP and Sn was obtained by XPS and electrochemical measurements.