Patent ID: 9403293
Filing Date: 2016-08-02
CPC Classification: B29C,B29K,C25D,G02B,Y10T

Claim Text:
1. A method of forming an anodized layer, comprising the steps of: (a) providing an aluminum base which has a surface that is made of aluminum; (b) anodizing the surface to form a barrier-type alumina layer; and (c) after step (b), further anodizing the surface to form a porous alumina layer which has a plurality of minute recessed portions, wherein the anodization in step (c) is performed with application of a pulse voltage, the pulse voltage having a pulse width of not more than 200 msec and a pulse interval of not less than 800 msec, wherein step (b) is performed in a first electrolytic solution, and step (c) is performed in a second electrolytic solution which is different from the first electrolytic solution, and wherein the different is that the first electrolytic solution is an aqueous solution containing at least one of acids or salts selected from a group consisting of ammonium tartrate, potassium sodium tartrate, boric acid, ammonium borate, ammonium oxalate, ammonium citrate, maleic acid, malonic acid, phthalic acid, and citric acid and the second electrolytic solution is an aqueous solution containing an acid selected from a group consisting of sulfuric acid, oxalic acid, tartaric acid, phosphoric acid, chromic acid and malic acid.