【China Aluminum Network】 Aluminum alloys and aluminum profiles usually require surface treatment to meet different requirements. Common aluminum alloy surface treatments include electroplating, spraying, drawing, anode, sandblasting, passivation, polishing, oxide film processing, etc. Sandblasting, the main role is to surface cleaning, sandblasting before painting (spraying or spray) can increase the surface roughness, contribute to the improvement of adhesion, but the contribution is limited, not as good as before chemical coating.

2. Coloring: There are two main processes for coloring aluminum: one is aluminum oxidation coloring process, and the other is aluminum electrophoretic coloring process. Various colors are formed on the oxide film to meet certain requirements. For example, black parts are commonly used for optical instruments, gold medals, and so on.

3, conductive oxidation (chromate conversion film) - for both protective and conductive applications.

4, chemical oxidation: thin oxide film, thickness of about 0.5 to 4 microns, and porous, soft, with good adsorption, can be used as the underlying organic coating, but its wear resistance and corrosion resistance are not as good as the anode Oxide film;

Aluminum and aluminum alloy chemical oxidation process according to the nature of its solution can be divided into two major categories of alkaline oxidation and acid oxidation.

According to the nature of the film can be divided into: oxide film, phosphate film, chromate film, chromic acid - phosphate film.

5, electrochemical oxidation, aluminum and aluminum alloy chemical oxidation treatment equipment is simple, easy to operate, high production efficiency, does not consume electricity, a wide range of applications, without the limitations of the size and shape of parts. Oxide film thickness is about 5 ~ 20 microns (hard anodized film thickness up to 60 ~ 200 microns), a higher hardness, good heat and insulation, corrosion resistance is higher than the chemical oxide film, porous, there is very Good adsorption capacity.

6. Spraying: External protection and decoration for the equipment are usually performed on the basis of oxidation. Aluminum parts should be pre-treated before coating to make the coating and the workpiece bonded firmly. Generally, there are three methods: 1. Phosphatization (phosphate method) 2. Chromation (chromium-free chromium) 3. Chemical oxidation.

7: Anodizing: It is the process of applying a thin layer of other metal or alloy on the surface of certain metals by using the principle of electrolysis. Brush plating for partial plating or repair. Roll plated for small parts such as fasteners, washers, pins, etc. Through electroplating, it is possible to obtain decorative protection and various functional surface layers on mechanical products, and also to repair worn and mismachined workpieces. The plating solution is acidic, alkaline, and acidic and neutral solution with chromium mixture. Regardless of the plating method used, plating tanks and hangers that are in contact with the plating product and the plating solution should have a certain degree of generality. Sex.

8, chemical polishing chemical polishing is the use of aluminum and aluminum alloy in the acidic or alkaline electrolyte solution in the selective self-dissolving effect, to leveling polishing year-round surface, to reduce its surface roughness, PH chemical processing methods. This polishing method has the advantages of simple equipment, no power supply, no limit on the size of parts, high throwing speed, and low processing cost. The purity of aluminum and aluminum alloys has a great influence on the quality of chemical polishing. The higher its purity, the better the polishing quality, and vice versa.

9. Passivation is a method of converting a metal surface into a state that is not easily oxidized, and delaying the corrosion rate of the metal.

An active metal or alloy in which the chemical activity is greatly reduced and becomes a noble metal state, called passivation.

The corrosion product produced by the action of the medium due to the medium has a dense structure and forms a thin film (often invisible), which tightly covers the surface of the metal and changes the surface state of the metal, so that the electrode potential of the metal is greatly increased. The positive direction jumps and becomes a passive state of corrosion resistance. If Fe → Fe + + standard potential is -0.44V, after the passivation jumped to +0.5 ~ 1V, and shows the performance of corrosion-resistant precious metals, this layer of film is called passive film.

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