Abstract
Polarization behavior of tin anodes in H2SO4 of various concentrations and stannous sulfate plating baths was investigated by potentiostatic method.
The anodes with various lead contents were prepared by a conventional melting process.
The results obtained were as follows:
(1) An oxide film was formed on the surface of tin anodes at potentials above passivation. The film was stable at potentials up to -0.4V(vs. S.C.E.), but it was dissolved when the potential was lowered to the spontaneous electrode potential of tin.
(2) The polarization for tin anodes depended upon the concentration of H2SO4, which made the passivity prominent at 3N.
(3) The effect of passivity increased with the decrease in purity of anode and lead was the most toxic among impurities.
(4) Organic addition agents to the plating bath inhibited the anodic dissolution.
(5) It was found that the measurement of anode potential-current density curve was used for selecting an excellent anode for each of various plating baths.
