The influence of polyaniline (PANI) top coat on corrosion behaviour of nickel plated copper

The polyaniline (PANI) was carried out on Ni plated (1 mm) copper (Cu/Ni). The synthesis was achieved under cyclic voltammetric conditions from 0.1 M aniline containing oxalic acid solutions. AC impedance spectroscopy (EIS) and anodic polarization curves were used to evaluate the corrosion performance of PANI coated and uncoated electrodes in 3.5% NaCl. It was found that nickel coating exhibited significant barrier property against the attack of corrosive agents. However, the porosity rate of nickel coating increased in time. PANI modified nickel plating provided much better barrier property to copper for longer periods. It was important that PANI coating by its catalyzing effect constituted lower permeability with the formation of stable nickel oxides on top of nickel plating and the catalytic behaviour of polymer film prevented increase of the porosity in longer periods, in such an aggressive medium.