Correlation between repassivation kinetics and corrosion rate over a passive surface in flowing slurry

Abstract

The effect of hydrodynamics of flowing slurry on anodic dissolution rate of passive metals was quantitatively evaluated using a theoretical model recently developed by the authors. The enhanced anodic dissolution over a passive metal in flowing slurry is dominated by the passive film breakdown caused by the impingement of solid particles and the decay of local current density over the impacted area due to repassivation. In the present study, the anodic current densities of 304 stainless steel and carbon steels were measured in flowing slurries under potentiostatic control condition. The difference in the repassivation modes indicates different repassivation mechanisms that depend on electrode material and corrosive medium. The parameters of repassivation kinetics experimentally determined enable estimation of the average anodic current density on the electrode surface in flowing slurry using the theoretical model. The theoretical predictions are in good agreement with the experimental data.