ELECTRODISSOLUTION KINETICS OF IRON IN CHLORIDE SOLUTIONS .7. EXPERIMENTAL POTENTIAL CURRENT OSCILLATIONS

Anodic oscillatory behavior of Fe in concentrated neutral chloride solutions was studied with rotating ring-disk electrodes. The dependence of oscillation characteristics on chloride concentration, potential/current density, and hydrodynamic conditions was obtained from linear potential sweep and potential/current transient measurements. Current oscillations were observed in both the current plateau and postplateau regions. Potential oscillations under galvanostatic conditions occurred when the current density was higher than the limiting current density. Both potential and current oscillations exhibited diverse waveforms, which disappeared at sufficiently high rotation rates. The oscillations are ascribed to alternate buildup and breakdown of a porous, nonprotective iron chloride salt film on the Fe surface. © 1990, The Electrochemical Society, Inc. All rights reserved.