2006 Volume 39 Issue 1 Pages 90-94
Environment-friendly anodizing of aluminum was developed. This method used high-pressure carbonic acid aqueous solution as an electrolyte solution. The anodic oxide film was formed under conditions that the anodizing voltage was 50–250 V, the electrolytic temperature 10–70°C, the electrolytic pressure 0.1–30 MPa and the electrolyzing time 10–600 min. The thickness of the oxide film increased with the increase in the anodizing voltage, electrolytic temperature, electrolytic pressure and the electrolyzing time. It was around 0.1–2.0 μm. The growth ratio of the barrier layer, which is defined by dividing the thickness of the barrier layer by the anodizing voltage, was 1.1 nm/V. The ratio of the average cell size to the anodizing voltage was 2.1 nm/V. These values were close to those of oxide films of aluminum produced in a conventional electrolytic bath such as the sulfuric acid bath.
