Kinetics of Passivation of Stainless Steel in Chloride Solution

When freshly generated stainless steel surface is passivating in the chloride solution, the true current decay law, i (t), that is independent of the methods of mechanically removing the oxide film on the metal surface and of parameters selected in experiment, follows
i (t)=C₁exp(-a₁t) + C₂exp(-a₂t)
The first term in this equation is associated mainly with the growth of MeOH adsorbed film, the second term is related to the growth of oxide film. At potentials above a critical potential that is well below the pitting potential measured from the surface covered by oxide film, corrosion pit would occur on the freshly generated surface. The film growth on the stainless steel in MgCl₂ solution follows the high field ion conduction mechanism.