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Surface treatment process of aluminum profiles
Common aluminum alloys and aluminum profiles are processed through various surface treatment techniques, including spraying, electroplating, wire drawing, sandblasting, anodizing, passivation, oxidation film, and polishing machine polishing.
1. Passivation is a method of transforming the surface of a metal into a state that is not easily oxidized, thereby slowing down the corrosion rate of the metal. A type of active metal or alloy in which the chemical activity significantly decreases and transforms into a noble metal state is called passivation.
2. Anodizing: It is the process of using the principle of electrolysis to deposit a thin layer of other metals or alloys on the surface of certain metals. Brush plating is used for local plating or correction. Roll coating is used for small parts such as fasteners, washers, pins, etc. After electroplating, it is possible to obtain decorative protection and various functional outer layers on mechanical products, as well as to correct worn and processing errors on workpieces. Electroplating solutions include acidic, alkaline, and acidic and neutral solutions containing chromium agents. Regardless of the plating method used, plating tanks, suspensions, etc. that come into contact with the finished product and plating solution should have a certain degree of universality.
3. Spraying: Used for external protection and decoration of equipment, usually carried out on the basis of oxidation. Aluminum profiles should undergo pre-treatment before painting to ensure a strong connection between the coating and the workpiece. There are usually three methods: (1) Phosphating (phosphate method), (2) Chromation (chromium free), (3) Chemical oxidation.
4. Sandblasting, the primary effect is surface finishing. Sandblasting before painting (spray painting or plastic spraying) can add surface roughness and contribute to the improvement of adhesion, but the contribution is limited and not as good as chemical coating pre-treatment.
5. Chemical oxidation: The oxide film is relatively thin, with a thickness of about 0.5-4 microns, porous, soft, and has excellent adsorption properties. It can be used as the bottom layer of organic coatings, but its wear resistance and corrosion resistance are not as good as anodic oxide films.
