The corrosion behavior of polyaniline top coat on nickel plated copper from neutral aqueous medium

Electrochemical synthesis of polyaniline (PANI) was achieved on 1 μm Ni plated on copper (Cu/Ni). PANI coating was synthesized under cyclic voltammetric conditions in a neutral medium, namely 0.15 M aniline containing sodium oxalate solution. Corrosion performances of PANI coated and uncoated electrodes were investigated in 3.5% NaCl, by means of ac impedance spectroscopy (EIS) and anodic polarization curves. It was shown that Ni plating increased the corrosion resistance of copper and its stable oxide layers achieved an efficient physical protection to Cu. It was found that PANI top coat provided an important barrier property to nickel plating on copper for longer periods, in such an aggressive chloride medium. It must be noted that the catalytic effect of polymer film had an accelerating effect on formation of nickel oxides. As a result PANI coating significantly contributed to the higher corrosion resistance of copper, increasing the protection efficiency and lifetime of nickel plating, for much longer periods.