ELECTROCHEMICAL EVALUATION OF A NEW-TYPE OF CORROSION PASSIVATION LAYER - ARTIFICIALLY PRODUCED AL2O3 FILMS ON ALUMINUM

A recently developed technique for the artificial production of an Al2 O3 film on ultrahigh-purity polycrystalline Al samples was employed. E lectrochemical impedance spectroscopy (EIS), Auger electron spectrosco py (AES), and grazing angle X-ray diffraction (GAXRD) were used to inv estigate the artificial oxide film. The growth of aluminum oxide in wa ter vapor (5 x 10(-7) Torr) enhanced by 100 eV electron bombardment re sulted in an artificial oxide film which exhibited a 10-30-fold improv ement in electrical resistance in 3.5% NaCl solution compared to oxide films of the same thickness grown at 300 K in the absence of electron bombardment (thermal excitation only). These measurements suggest tha t the artificial aluminum oxide film may provide superior corrosion pa ssivation qualities compared to thermally grown oxide films. The amorp hous nature of the artificial oxide film was confirmed by GAXRD.