GB1327263A - Continuous anodic oxidation method and apparatus for aluminum and alloys thereof - Google Patents

Abstract

1327263 Anodizing MATSUSHITA ELECTRIC INDUSTRIAL CO Ltd 15 Sept 1970 [18 Sept 1969 9 Dec 1969 (2) 25 Nov 1969 11 Dec 1969 (2)] 44079/70 Heading C7B An aluminium surface is continuously oxidized while moving the surface vertically past a liquidpermeable material through which electrolyte is discharged. As shown a conducting plate 2 forms . one wall of a container, opposite to which is a discharge port 6 covered with a liquid-permeable layer 5. Electrolyte such as a sulphuric acid solution is fed to inlets 1 and discharges through membrane 5 and then flows down the moving aluminium surface while a voltage is applied across the plate 2 as cathode and the aluminium body 8 as anode. The opposite surface of the body 8 may be simultaneously treated by a similar device. In a modification, Fig. 2 (not shown), cooling liquid is projected against the face opposite that being treated. In another modification, Fig. 3 (not shown), pairs of opposed anodizing devices are situated at different levels for the body to move past the pairs in succession and opposed cooling discharge orifices alternate with the pairs of anodizing devices. For treating wire an annular container having its inner surface formed of the liquidpermeable material discharges electrolyte on to a wire moving along the axis thereof Fig. 5 (not shown). Alternatively discharge may be from the outer circumference on to a plurality of moving wires, Fig. 6 (not shown). Using 30 per cent sulphuric acid as the electrolyte maintained at 30‹C., current densities up to 600 amps/sq.dm. may be used without yellowing of the film. Anodizing with subsequent cooling of the metal using the apparatus of Fig. 3 produces a cracked oxide film of improved flexibility.