ANODIZATION RATE AND AUGMENTATION FACTOR OF ANODIC ALUMINUM-OXIDE FILMS

This paper presents a determination method for both the oxidation rate and the augmentation factor of anodic oxide films. The augmentation factor, which is the ratio of pure oxide thickness to that of its initial metallic thickness, is determined by thickness and optical absorption measurements. The oxidation rate is defined as the ratio of oxide thickness to the forming anodization voltage and it is determined from the dependence of thickness on anodization voltage. The augmentation factor and oxidation rate of anodic aluminum films, oxidized in 3% aqueous ammonium tartrate (pH=5.5) at room temperature (∼25 °C), are determined as 1.5 and 13.2 Å/V, respectively. The thickness of the residual metallic aluminum film corresponding to that of the upper limit of the anodic oxide film is estimated as ∼35 Å.