Anodic Polarization of Tin, Nickel, and a 65/35 Tin-Nickel Alloy in Alkaline Media Containing Halide Ions Available to Purchase

Anodic polarization of tin, nickel, and a tin/nickel alloy was studied by the potentiostatic technique, in KOH and K₂CO₃ solutions in the concentration range 0.1 to 0.5M. The effect of Cl^–, Br^–, and I^– ions, 10^–4 to 10^–1M, on the anodic behavior in both KOH and K₂CO₃ solutions was also investigated. The results are presented along with probable dissolution and passivation mechanisms that were observed during the experiments. For tin, I_cc was found to increase with increasing alkali concentration, while I_p was not affected, and their values in K₂CO₃ were much lower than those obtained in KOH solutions. Active regions were not observed in the case of Ni and the Sn/Ni alloy in both alkali solutions. The presence of halide ions was shown to decrease the value of I_cc for Sn in both KOH and K₂CO₃ solutions. A large increase in I_p for Sn and Ni was observed in K₂CO₃ solution containing 10^–1M Cl^– ion, while I_p for the alloy remained unaltered.