In this paper the authors have attempted to present a coherent picture of the present knowledge of ‘anodization of aluminum’ based upon the research conducted at Hokkaido University during the past fifteen years. General background for the research, and typical experimental results obtained with acidic and neutral solutions, which produce porous type and barrier type films, are described. The mechanism of film formation and its dissolution, and the composition and properties of the formed oxide are discussed with special attention to the following problems: (1) Initiation and growth of pores in the initial periods of anodizing, (2) Effect of electrical field on the dissolution of oxide, (3) Distribution of electrolyte anions in the oxide, (4) Transport of Al
3+and O
2- ions in the barrier layer during anodization. The authors demonstrate, in many aspects, that the mechanism of oxide formation is the same for both types of films, and that the porous type films are formed only in the special case where there is local dissolution of oxide, produced by the electrical field.
抄録全体を表示