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一 The cause of anodic oxidation aluminum profile
1, Oxidation dyeing principle
A&L Aluminum-A professioanl aluminium profile manufacturers. As is known to all, anodic oxide film is composed of a perpendicular to the metal surface of hexagonal crystal cell, every cell center has a film hole, and with a strong adsorption capacity, when the oxidation of aluminum in the dye solution, dye molecules by diffusion into the film hole of oxide film, at the same time and the oxide film formation is difficult to separate ionic bond and covalent bonds. This bond is reversible, desorption will happen under certain conditions. After dyeing, therefore, must pass a hole sealing process, the dye fixation in film hole, with increase of the oxide film properties, such as corrosion resistance, abrasion resistance.
2, The influence of anodic oxidation process for dyeing
In oxidation dyeing the entire process, because of the oxidation process causes poor dyeing is common. Film thickness of oxide film and the pore uniformity is the premise and foundation of dyeing with uniform color, in order to obtain uniform oxidation film, ensure sufficient flow, cooling capacity, ensure a good electrical conductivity is very important, also is the stability of the oxidation process.
Sulfuric acid concentration, control in 180-200 g/l. A slightly higher concentration of sulfuric acid can promote the dissolution reaction of oxide film is accelerated, conducive to the expansion of pore, more easier to stain;
Aluminum ion concentration, control in 5 to 15 g/l. Aluminum ion is less than 5 g/l, the generated oxide film adsorption capacity is reduced, affect color speed, aluminum ion is greater than 15 g/l, the uniformity of the oxide film is affected, prone to irregular membrane layer.
Oxidation temperature, control at 20 ℃ or so, oxidation of bath temperature on the dyeing effect is very significant, too low temperature oxidation film hole density, the dyeing speed significantly slow; Greens of high temperature oxide film loose, easy pulverization, not conducive to the control of dyeing, the oxidation tank temperature difference should be within 2 ℃ advisable.
Current density, the control during the 120-120 a/m2.Current density is too large, in the case of film thickness must, will shorten the aluminum electrolysis in the slot time, accordingly, oxide film dissolve in the solution decreases, film hole density, dyeing time longer. At the same time, the film easy pulverization.
Film thickness, dyeing required thickness of oxide film is in commonly 10 (including m above solution. Dye film thickness is too low, easy to appear uneven phenomenon, at the same time for dyeing dark color such as black, because the film thickness is not enough, lead to dye the precipitation amount is limited, can’t meet the requirements of the color depth.
In a nutshell, anodic oxidation as the dyeing process before, is the foundation of dyeing. Anodic oxidation problem before dyeing, it's hard to see or not see, once dyes, we can clearly see the phenomenon such as uneven color. Meanwhile, production workers often attributed the problem to dyeing is not normal, rather than on the oxidation process for reason. I just contact oxidation dyeing in these mistakes.