Effect of the addition of oxo-anions on the corrosion and passivation of tin in synthetic industrial water

Effect of the addition of oxo-anions MoO4 2 , SiO4 2 , HPO4 2 and HCO3 on the corrosion and passivation of tin in a synthetic medium similar to industrial water has been studied by using electrochemical techniques. The results show that tin manifests a passivation phenomenon with breakdown of passivity. Addition of oxo-anions leads to retard a breakdown of passivation and the inhibition of pitting process of tin. The more marked inhibiting effect is obtained in the presence of MoO4 2 and SiO4 2 . The detailed study of the influence of the MoO4 2 shows that the pitting sensitivity of tin decreases when the molybdate concentration increases in solution. Then, these ions offer a good efficiency even at high temperature and for a chloride concentration up to 0.5 M.