Comparative study of the action of oxo-anions on the corrosion and passivation of tin and tinplate in synthetic industrial water

The synthetic industrial water (Cl-, SO4 and HCO ), similar to industrial water used in fish canning industry in Agadir (southern of Morocco), was tested as an aggressive medium towards tin and tinplate at room temperature (20±1°C). The corrosion and passivation behaviours of these materials are studied in the presence of the oxo-anions (molybdate, silicate and phosphate) at various concentrations. The technique used in this study is the electrochemical measurement. The results obtained show that both tin and tinplate manifest a comparable electrochemical behaviour in synthetic industrial water. Tinplate presents always a resistance against the two types of corrosion as well as the tin. As for the presence of the oxo-anions in solution, they accelerate the uniform corrosion (untinning) and prevent the pitting corrosion of tinplate and their action is more pronounced in the case of tinplate than the tin electrode.