ELECTROCHEMICAL-BEHAVIOR OF IRON AND IRON-OXIDE THIN-FILMS IN ALKALINE (1 M KOH) AQUEOUS-SOLUTION - A VOLTAMMETRY STUDY FOR CATHODIC INSTABILITY OF COATING METAL INTERFACE/

The electrochemical behaviour of thin film metallic iron and the iron oxides in 1M KOH anaerobic aqueous solution was studied by cyclic volt ammetry technique. The material studied was of thin film (50 nm) iron supported on a glass substrate, and the oxide thermally formed on the iron film. The voltammetry of thin film iron on glass was similar to t hat of low carbon steel and gave a convenient means for preparing spec imens for obtaining information relevant to the degradation of structu ral steel. In this report, the formation of various types of oxides on the iron surface are identified, and the electrochemical stability of the oxides and their relevance to the cathodic disbonding of organic coating from cathodically protected steel pipelines are discussed.