Electrochemical and Ellipsometric Investigations of Passive Films on Iron in Borate Solutions: II . Cathodic Reduction of Passive Films on Iron

Passive films formed under strictly controlled conditions during anodic polarization of iron in borate buffer solution were reduced in the same solution with a constant cathodic current. The cathodic charge consumed for the reduction of passive film was greater than the theoretical value calculated under the assumption that was reduced to Fe 2+ . The higher the oxidation potential was and the longer oxidation time was employed, the greater was the consumed charge found experimentally. At certain characteristic thicknesses of the passive film associated with changes in film growth during its formation, inflections of the vs. time and vs. film thickness were observed.