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Difference between coloring and dyeing details of aluminum anodizing

Release time:

2020-11-27 11:33

Aluminum is a kind of light, soft non-ferrous metal, the molecular composition of aluminum itself is very easy to oxidize in the air, so we came up with a way that is aluminum oxidation process, the specific situation is to grow a protective film on its outer layer, so that it is durable, and can be dyed into colorful colors, beautiful atmosphere.
Difference between coloring and dyeing details of aluminum anodizing
1. Electrolytic coloring

The so-called principle of electrolytic coloring is an electrolytic coloring film based on a transparent anodic oxide film of sulfuric acid primary electrolysis, and an oxide film (also called a secondary electrolytic film) is electrolytically colored by alternating current in a solution containing a metal salt. Its electrolytic coloring film has better weather resistance, light resistance and service life than the dyeing film, and its energy consumption and coloring cost are far lower than the overall coloring film. At present, it is widely used for coloring aluminum alloy profiles, but the electrolytic coloring is monotonous, usually only bronze, black, golden yellow, jujube red and so on. And the operation is not easy to control.

2. Organic dyeing

Organic dyeing is based on the theory of material adsorption, adsorption has physical adsorption and chemical adsorption, physical adsorption is the adsorption of molecules or ions by electrostatic force; chemical adsorption, the adsorption by chemical force, the combination of the two to produce organic dyeing, usually at a certain temperature. Due to the high porosity of the anodic oxide film, strong adsorption capacity and easy organic dyeing, this method is fast, bright color, easy to operate, after dyeing by sealing treatment, the dye can be firmly attached to the membrane hole, improve the corrosion resistance of the film, anti-fouling ability, until you can maintain a beautiful color, colorful appearance. To meet the modern society people review and pursuit of the United States, improve the product market competition ability.

Organic dyeing has some characteristics and requirements for oxide film: 
1. The oxide film layer should have sufficient porosity
2. The inner wall of the membrane hole to maintain a certain activity
3. The anodic oxide film obtained by aluminum in sulfuric acid solution is colorless and porous, so it is suitable for dyeing.
4. The oxide film layer must have a certain thickness, thin film layer can only be dyed very light color
5. Hard anodic oxide film with chromic acid conventional oxide film layer, are not suitable for organic dyeing
6. The oxide film layer shall be complete and uniform, and there shall be no defects such as scratches, sand holes and pitting corrosion.
7. The film itself has a suitable color, and there is no difference in metallographic structure, such as different grain sizes or severe segregation, etc., aluminum profile manufacturers also have certain requirements for aluminum alloy materials. When the content of silicon, magnesium, manganese, iron, copper, chromium, etc. in the alloy composition is too high, it will often cause the oxide film to be dull, and the color change will occur during dyeing. This is the specific process of anodic oxidation to explain.

Anodic oxidation of aluminium