Pitting corrosion behavior of lead in Na2HPO4–NaNO3 solutions

The pitting corrosion behavior of lead in 0.10 M Na₂HPO₄ solutions containing various concentrations from NaNO₃ has been studied using potentiodynamic anodic polarization and SEM techniques and complemented by both X-ray and FT-IR surface analysis. Above certain critical NaNO₃ concentration, the aggressive anions prevented the oxygen evolution and induce pitting on the Pb electrode surface. Pitting-initiation and pitting-growth were found to depend on the concentration of the aggressive NO^– ₃ anions. Also, some changes in the (I–E) curves within the active, pre-passive and passive regions were recorded. These changes imply mainly the appearance of new stages and peaks. This behavior gives an indication for definite changes in the pit-characteristics, which interpreted in terms of solution composition and kinetics of its associated processes within pits.