Abstract
In order to improve the alkaline corrosion resistance of anodized aluminum, silicon oxide coating film was formed on an anodic oxide film by the sol-gel process using the sol solution, to which a tetraethoxysilane and a multiple alcohol having different vapor pressures were added. The composite films consisted of a porous layer of anodic oxide film filled with silicon oxide and a silicon oxide coating layer deposited thereon. The alkaline duration time of composite films was increased as the repetition number of dip-coating was carried out untill five dip-coating, and the alkaline duration time of composite film prepared by five dip-coatings was about 1.6 times that of the anodic oxide film after the boil sealing. According to the changes of the internal pressure in the vacuum chamber and evacuation time, the amount of exhaust gas from composite film was clearly less than that of the anodic oxide film after the steam sealing and was approximately similar to that of the anodic oxide film before the steam sealing. From the mass spectrometric analysis of exhaust gas, hydrocarbon and water were mainly detected in the exhaust gas from the composite film. The water amount contained in each film was also decreased in the order of the sol-gel composite film<the anodic oxide film before the steam sealing<the anodic oxide film after the steam sealing.
