Abstract
Impedance of aluminum oxide films anodized in a sulfuric acid bath is measured in nickel sulfate-boric acid mixed aqueous solution. When the oxide films are not cathodically polarized, the measured impedance is mainly the impedance of barrier layer, and the phase angle is 84°. This impedance is a capasitive impedance. When cathodic voltage is applied on the oxide films, the impedance suddenly decreases. During cathodic polarization, the impedance gradually increases and phase angles are in the range between 10°to 40°. This impedance is ohmic impedance. Separation of non-Faradic impedance and Faradic impedance was impossible in this study.
