Use of Electrochemical Impedance Spectroscopy to Study the Corrosion of Tin in Citrate Solution

The corrosion and passivation of tin anode in citrate (0.01 to 1.0 M) solution was investigated using steady state polarization, impedance spectroscopy and cyclic voltammetric techniques. Before permanent passive region, two anodic peaks were observed in the anodic polarization curve, corresponding to the consecutive electroformation of Sn(II) and Sn(IV) species. The corrosion current was calculated by the Tafel extrapolation procedure at different concentrations of citrate ion and different pH values. Also, the corrosion resistance at the corrosion potential was calculated from the Nyquist diagram of different concentration of citrate ion. It was found the latter gives more precise results.