Some reasons for the uneven color of the oxide film of aluminum material

Aluminum profile oxidation

Three possible causes of aluminum profile oxide film color is not uniform:

 (1) when anodized the aluminium profiloe the workpiece area is too large, the swing range in the slot is too large, the edge and the center position and solution contact, update, exchange had large differences, resulting in inconsistent color film. Methods of prevention: small swing range when anodized the aluminium profile, also could be static treatment, but when the solution temperature is too low could lead to map or spots, which is not natural.

 (2) when the aluminum clad parts was under destruction, by cutting off, outer alclad belongs high quality aluminum, enclosed inner layer is miscellaneous aluminum, two aluminum differences, so the oxidation after “benign vitiligo” like spots. The customer often do not quite understand of this phenomenon, manufacturers should do more to explain the work, explain why and how, in order to avoid misunderstanding.

 (3) the process operation problems

The workpiece caustic treatment is not thorough, the local original film, failed to remove all dirt;

after alkali etching is not immediately carry out light processing, the surface is still a basic;

The workpiece contact with foreign material in the transmission process.

When the film uneven color to look for reasons from many aspects, corresponding measures should be taken to solve.

Fault a reader calls asking the workpiece by after alkali etching conductive oxide film is difficult to obtain the reasons caused by alkaline etching liquid aluminum ion accumulation is too high, after exclusion of many factors and it is difficult to form the conductive oxide film, take into account whether the high aluminum ions alkali etching solution, the other said alkaline corrosion solution is very thick. But the alkali corrosion speed is not fast. Then the author suggests changing alkaline corrosion solution, because after alkaline etching liquid used for too long will aluminum ion accumulation of excess, aluminum ions on the surface of the workpiece is difficult to elution, thus affecting the aluminum surface and the conductive oxide solution contact, thus affecting the formation of oxide film. Another suggestion is that if the unconditional replacement of alkaline etching solution, the workpiece after alkali etching after water rinse immediately after the flow of water rinse, and then a light in a hydrofluoric acid containing concentrated nitric acid, then rinse thoroughly after conducting oxidation treatment. After the readers to telephone said after alkali etching with hot water and the effect is very good. The author is the experience, and in hot water after the hot water and immediately immersed into the water quickly leave, to prevent the workpiece by dry due to oxidation and affect the formation of conductive oxide film.

Post time: May-08-2018