Process and apparatus for continuous anodic treatment

Abstract

Abstract An aluminium rod, wire or strip 12 is continuously anodized to produce a porous oxide film thereon by successively moving it through an electrolytic cleaning cell 10 and anodizing cell 11, wherein there is maintained in contact with the electrolyte an anode for cell 10, e.g. consisting of upper and lower lead anodes 14, 15, and a cathode for cell 11, e.g. consisting of upper stainless steel cathode 18 and preferably a lower graphite electrode 19, the cleaning and anodizing cells being in open communication with one another through a connecting zone so dimensioned that leakage current is less than a quarter of the total current, the electrolyte being maintained in turbulent flow lengthwise of the moving aluminium e.g. by re-circulating the electrolyte collected from <PICT:1087256/C6-C7/1> pipes 51, 52 at the strip-inlet end of the anodizing cell to the strip-outlet end through pipes 67, 68 using pump 117, and D.C. 135 being passed between the anodes and (one or both) cathodes through the electrolyte and strip 12 at a current density of at least 100 A.S.F. of aluminium surface exposed in the anodizing cell 11. The electrolyte in the anodizing cell may be separated into two parts by the strip (as shown), one part contacting the cathode 18 and the other part contacting an anode 19 (switch contact 139) whereby oxide film is formed on one side only of the strip. Alternatively both parts may contact cathodes (switch contact 143), preferably the potential of the two cathodes 18, 19 being at different values (switch contact 144 connecting cathode 19 through a variable resistor 145) whereby oxide films of different thickness are formed on the two sides of the strip.

Inventors

• 👤 W Cooke
• 👤 D Bury
• 👤 P Smits
• 👤 J Cote

Bibliographic Details