Abstract
Pitting corrosion of 1018 carbon steel electrode in 0.1 M NaHCO3 solutions containing increased additions of NaCl was studied using potentiodynamic anodic polarization technique. The pitting corrosion potential varies with the logarithm of Cl- ion concentrations according to segmoidal S-shaped curves. These curves were explained on the basis of formation of passivatable, limiting active and continuously propagated pits depending on the range of Cl- ion concentrations. Addition of some 3-substituted pyrazole caused a shift of the pitting potential in the noble direction accounting for increased resistance to pitting attack.