Method for anodizing aluminum material

Abstract

A process for the anodization of an aluminum material which can form an anodized film free from local destruction or spalling even if supplied with electric current through the surface of the anodized film in the double-power supplied electrolytic process and/or multi-stage power supply electrolytic process to secure the desired quality and properties. A process for the anodization of an aluminum material can be provided, which comprises anodizing the surface of elongated aluminum or aluminum alloy which advances through a power supply part and an electrolytic part, and then supplying electric current to the surface of said anodized web through another power supply part in such a manner that the following relationships among the current density, the electric supply time and the amount of anodized film thus produced are satisfied: (Current density).sup.4/3 .times.(Supply time).sup.3/2 .times.(Amount of anodized film).sup.2/3 .ltoreq.5,100 (1) 1.ltoreq.(Supply time).ltoreq.10,0.5.ltoreq.(Amount of anodized film).ltoreq.6.0 (2) wherein the current density, the supply time and the amount of anodized film are represented in A/dm.sup.2, second and g/m.sup.2, respectively.

Dependencies are inferred from the claim text.