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Five Advantages of Aluminum Alloy Anodizing
Time:2023.08.17 Source: Yuhuan Huahua Metal Products Factory Clicks:

Anodizing is a highly favored processing technology in the aluminum alloy industry. Today, we will talk about the five advantages of aluminum alloy anodizing.

1. Improved wear resistance

Aluminum alloy substrates are particularly prone to scratches and wear, and the hardness of aluminum alloys cannot be compared to steel. But the surface of anodized aluminum alloy profiles will be very hard, wear-resistant, and not easily scratched. This is due to the significantly increased hardness of the surface oxide film.

Hardness of Aluminum Anodizing

The hardness of aluminum anodized film is generally between 200 and 500HV. Anodizing is an exothermic processing process, and high temperatures can enhance the hardness of anodizing.

Heating the aluminum anodized film removes moisture from it. In addition, the crystal structure of the anodized film also changes. Within a certain range of dehydration and structural changes in the anodized film, the hardness of the anodized film increases with the prolongation of heating time. If the aluminum anodized film is maintained to protect the aluminum substrate, the anodizing performance will deteriorate, and the hardness of the anodized film cannot be maintained, In order to maintain the change in hardness of the anodic oxide film during heating within the performance range of the anodic oxide film.

2. Improved corrosion resistance

Due to the dense oxide film on the surface of aluminum alloy, this oxide film can better prevent direct contact between aluminum and air.

When anodizing aluminum and its alloys, the following reactions occur at the anode: 2Al ->6e -+2Al3+; The following reactions occur at the cathode: 6H2O+6e -->3H2+6OH -. At the same time, the acid chemically dissolves aluminum and the generated oxide film, and the reaction is: 2Al+6H+-->2Al3++3H2; Al2O3+6H+-->2Al3++3H2O.

The film layer on the surface of the aluminum shell produced by heating and extrusion is very weak. Aluminum is a lively metal that is easily combined with substances such as oxygen and water in the air, and then undergoes chemical reactions to generate Al2O3 and Al (OH) 3, greatly reducing its corrosion resistance; After anodizing, the film layer will thicken to resist the corrosion of acid and alkali substances, thereby improving the service life of the aluminum shell.

3. Good decoration

Before anodizing and sealing of aluminum profiles, there will be many and dense pores on the surface, which can easily adsorb some metal salts or dyes, resulting in the formation of rich and colorful colors on the surface of aluminum products.

The anodic oxide film obtained from aluminum and aluminum magnesium alloys in sulfuric acid solution is colorless and transparent, while the oxide film of aluminum alloys containing manganese or silicon is light gray or brownish gray.

The film thickness of pure aluminum can reach 40um, and the thickness of the general protective decorative oxide film is 5-20um. The sulfuric acid oxide film is porous and has strong adsorption capacity, with a porosity of 10-15%. The film layer is suitable for dyeing or electrolytic coloring, and is used for decoration or identification marking. To improve the protective performance of the film, sealing treatment should be carried out. When the use conditions are harsh or the corrosion resistance requirements are high, additional painting is also necessary. The paint film and oxide film have good adhesion.

4. High end visual effects

Anodizing will display the metallic texture of the entire aluminum alloy workpiece.

5. Good binding ability

Anodizing is fundamentally different from sandblasting, spraying, or electrophoresis. The anodized oxide film is attached to the surface of the product, not the inner oxide film is integrated with the product. It is an electrochemical reaction that occurs inward on the surface. Therefore, the anodic oxide film will not exhibit a film drop phenomenon similar to that found in sandblasting and spraying.

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