| 摘要 |
PURPOSE:To increase the diameter of a bore of an oxide film and increase alpha-value and epsilon-value by processing aluminum or its alloy in specific first, second, third and fourth steps. CONSTITUTION:In the first step in which a substrate such as an aluminum is subjected to anodic oxidation processing to form a porous anodic oxide film, a sulfuric acid bath, for example, is used. In the second step in which the porous anodic oxide film is subjected to immersion processing in an acidic solution, a phosphoric acid bath, for example, is used. In the third step in which the film is subjected to electrolysis and coloring in a bath including a metal salt, an ordinary process may be used. In the fourth step in which hole sealing processing is performed, a steam hole sealing process or the like is used. By these steps, the alpha-value and the epsilon-value can be improved and dissolution of the film is made uniform. It is, therefore, possible to remove the irregularity in the selective absorption characteristic. |
