The composition and heat treatment state of aluminum and aluminum alloy have great influence on the appearance and properties of anodized aluminum profile. For example, in sulfuric acid anodizing, aluminum alloy with high copper content has loose and porous film due to the dissolution of “CuAl”. The alloy film is gray. Aluminum alloy with more than 5% copper or more than 7.5% silicon should not be anodized with chromic acid. Aluminum alloy with high content of copper or silicon can not be anodized by paste method to generate anodized aluminum profile, but high frequency hard oxidation power supply must be selected.
For decorative anodizing, the requirements for aluminum and aluminum alloy materials are higher. Generally, only pure aluminum, aluminum cladding, aluminum magnesium, aluminum manganese alloy can be dyed with bright colors. Generally, anodized aluminum profile, which is also made of these materials, has strong cost performance. Therefore, the vast majority of anodized aluminum profile suppliers will use such materials. However, for the alloy with high content of silicon and iron, the oxide film can only be dyed with deep color because of its dark color. When aluminum and aluminum alloy parts are subjected to decorative anodizing, the following points should be noted in material selection:
1. High purity aluminum or 5a66 aluminum magnesium alloy with aluminum content higher than 99.99% must be selected for parts with mirror surface. A colorless, transparent and bright coating can be obtained by sulfuric acid anodizing after chemical or electrochemical polishing, which can be dyed with various bright colors.
2. For parts requiring lower surface brightness than above, industrial high-purity aluminum with aluminum content higher than 99.9% and aluminum magnesium alloy of lt65 and lt67 can be selected.
3. For parts with general decoration requirements, there is a maximum allowable content requirement for other components and impurities in aluminum materials, and aluminum magnesium alloy is preferred.
Nowadays, more and more anodized aluminum profile suppliers begin to pay attention to anodized aluminum profile process flow. A large part of the reason is that more and more anodized aluminum profile suppliers appear, which makes the anodic oxidation process more operable and selective. In the process of anodized aluminum profile suppliers' competition, excellent processing and product service will drive the sales of anodized aluminum profile, so as to improve the competitiveness of the company in this field.
At the same time, when selecting aluminum materials to produce anodized aluminum profile, attention should be paid to the following aspects:
1) There should be no serious scratch, structure defect and inclusion on the surface of aluminum material. They affect the appearance and corrosion resistance of the oxide film.
2) Some aluminum alloys should be heat treated with reasonable specifications. The grain size has a certain influence on the structure and properties of the oxide film. Coarse grains react unevenly in the oxidation process, and often appear orange peel appearance. Therefore, it is generally expected that aluminum has fine grain structure. This is also the choice of the vast majority of anodized aluminum profile suppliers.
When selecting oxidation equipment, attention should also be paid to:
When choosing hard oxidation power supply, it is recommended to use water-cooled high-frequency hard oxidation power supply. Because the output waveform is square wave, and the energy-saving effect is obvious, and the film coating speed is fast, it is recommended to use.
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