Aluminum is a commonly used metal in industry and life. In the process of aluminum processing, surface treatment is an important link, with various methods and different effects. Sometimes only one method can meet the needs, and sometimes multiple methods are needed to cooperate to meet the requirements of the product. Among them, anodic oxidation is the most widely used method. Next, let's talk about the role of anodizing in aluminum surface treatment.
Enhance the corrosion resistance of aluminum products
Anodizing can obtain an oxide film on the surface of aluminum products, which has very stable chemical properties and strong corrosion resistance. For example, aluminum materials anodized in chromic acid solution have dense oxide film on the surface and good corrosion resistance, which is particularly suitable for riveted parts and weldments; The aluminum material anodized in sulfuric acid solution has a higher thickness of oxide film and stronger adsorption capacity, but because the pores are larger than the former, it needs to be properly filled and sealed.
Improve the adsorption of aluminum products to pigments
Anodized aluminum products after chemical or electrochemical polishing will form a transparent oxide film on the surface. Moreover, this oxide film is porous and has good adsorption capacity. It can effectively adsorb a variety of organic or inorganic dyes, as well as paints and organic films. Therefore, try anodizing the aluminum material before painting or coloring, so that the pigment can be better combined with the aluminum material, so that the aluminum products can have a variety of bright colors and increase the appearance of beauty. Not only that, this color film can also play a good anti-corrosion effect.
Enhance the wear resistance of aluminum products
The oxide film formed by anodic oxidation is not only anti-corrosion, but also very dense. Through hard anodic oxidation of aluminum and aluminum alloy, a layer of aluminum oxide film with large thickness, high hardness and low roughness can be obtained on the surface. And the empty structure will also absorb some lubricating oil. The existence of this oxide film greatly enhances the wear resistance of aluminum products, which can effectively adapt to the friction working state, such as being used as automobile engine cylinder, piston and other parts. Such an oxide film can be obtained by anodic oxidation in sulfuric acid or oxalic acid solution.
Realize the electrical insulation of aluminum products
The chemical structure of the film obtained by anodic oxidation is metal oxide rather than metal, so it has strong electrical insulation. Some aluminum materials require electrical insulation, such as the dielectric layer of capacitors. This can be achieved by anodic oxidation.
As the electroplated bottom layer of aluminum products
Before electroplating of aluminum and aluminum alloy products, the bottom layer must be applied first, and then electroplating can be carried out. There are many methods to apply the bottom layer on the surface of aluminum products, including galvanizing, zinc dipping, electroless nickel plating, and of course, anodic oxidation. Due to the porosity of the oxide film obtained by anodic oxidation, it can play a good role in promoting the subsequent electroplating processing effect.
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