THE DISTRIBUTION OF CURRENT AND FORMATION OF A SALT FILM ON AN IRON DISK BELOW THE PASSIVATION POTENTIAL

Current distribution and surface structure were studied for an iron disk in 1M sulfuric acid subjected to a uniform axial velocity at potentials cathodic to the passivation potential. The surface of the electrode was transformed from a granular to a smooth surface at potentials at which the current was observed to oscillate. The smooth surface was seen initially at the periphery of the electrode and grew inward toward the center of the disk as the potential was increased. In contrast to data obtained for partially passivated electrodes, the rate of corrosion was higher at the outside of the disk than in the center.