| 摘要 |
PURPOSE: To improve film adhesion and corrosion resistance by roughening the surface of a phosphated-chromated film, formed on the surface of a clad sheet, to a prescribed roughness. CONSTITUTION: A cladding layer material of a clad material consisting of a core material and the cladding layer material is composed of pure aluminum of >=99.7% purity. Further, a surface-roughened phosphated-chromated film, which has <90% flat part and >=2cm<2> per cm square and also has recessed parts having 0.05-0.5μm depth from the flat part, is provided onto the outside surface of the cladding layer material. This surface-roughenedphosphated- chromated film can be formed by using a treatment solution having a weight concentration ratio of hydrofluoric acid to chromic of 0.23-0.7. Further, the amount of chromium at the time of phosphate-chromate treatment is regulated to 5 to 60mg/m<2> , preferably to 10 to 40mg/m<2> . Although hydrofluoric acid used for this treatment is ordinarily used for accelerating film formation, it also produces an effect on surface roughening by means of etching effect, prior to film formation.
|
