Anodized aluminum film

Abstract

Provided is an anodized aluminum film formed on a surface of a substrate that comprises aluminum or an aluminum alloy, the anodized aluminum film having a structure constituted of a single anodized film layer or a structure composed of superposed anodized film layers of two or more different kinds, wherein the outermost anodized film has a degree of film formation, defined by equation (1), of 1.3 or more and the proportion of the thickness of this anodized film in the entire film thickness is 3% or higher. Thus, the anodized aluminum film is inhibited from cracking in bent portions. As a result, the substrate is inhibited from corroding in corrosive-gas atmospheres, and a decrease in withstand voltage characteristics due to film cracking is inhibited. With this anodized aluminum film, enhanced withstand voltage characteristics can hence be attained: Degree of film formation=(thickness of anodized film)/(substrate thickness loss by anodization)  (1).

Dependencies are inferred from the claim text.