Common Surface Treatment Method - Anodizing

An electrolytic anodizing process, in which the surface of aluminum and aluminum alloys is usually converted into an anodized film, which has protective, decorative and some other functional properties.

Based on this definition, the anodizing of aluminum only includes the process of generating an anodized film. The metal or alloy workpiece is used as the anode, and an anodized film is formed on its surface by electrolysis.

The metal oxide film changes the surface state and properties, such as surface coloring, improving corrosion resistance, enhancing wear resistance and hardness, protecting the metal surface, etc.

For example, aluminum profile anodizing, its alloys are placed in the corresponding electrolyte (such as sulfuric acid, chromic acid, oxalic acid, etc. as the anode, and electrolysis is carried out under specific conditions and the action of an applied current.

The aluminum or its alloy of the anode is oxidized, and a thin layer of aluminum oxide is formed on the surface, with a thickness of 8 to 30 microns, and the hard anodized film can reach 25 to 150 microns.

After anodizing, aluminum or its alloy has improved its hardness and wear resistance, which can reach 250-500 kg/mm2. It has good heat resistance, the melting point of hard anodized film is as high as 2320K, excellent insulation, and the breakdown voltage is as high as 2000V, which enhances the corrosion resistance.

It will not corrode in ω=0.03NaCl salt spray for thousands of hours. There are a large number of micropores in the thin layer of anodized film, which can absorb various lubricants and is suitable for manufacturing engine cylinders or other wear-resistant parts. The film has strong adsorption capacity of micropores and can be colored into various beautiful and bright colors.

Non-ferrous metals or their alloys (such as aluminum, magnesium and their alloys) can be anodized. This method is widely used in mechanical parts, aircraft and automobile parts, precision instruments and radio equipment, daily necessities and architectural decoration.

More reading:

Common Surface Treatment Method

Electrophoresise

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