Alkaline corrosion resistance of anodized aluminum coated with zirconium oxide by a sol-gel process

To improve the alkaline corrosion resistance of aluminum, composite films w ere prepared that consisted of a porous layer of anodically grown aluminum oxide filled with zirconium oxide, with a zirconium oxide coating layer tha t was deposited thereon via the sol-gel process, using a dip-coating techni que. The alkaline corrosion resistance of these composite films was extreme ly improved when this coating layer was placed on an anodic oxide film. Com parisons of the composite film and conventional anodic oxide film showed th at the alkaline corrosion resistance of the composite film was increased by a factor of 24-50. Because these composite films, which have high corrosio n resistance, indicated a vibration phenomenon of voltage in the duration t ime curve of the electromotive force measurement, the composite film had a self-repairing action for alkaline corrosion.