In order to improve the corrosion resistance of the 3 series aluminum coil surface, the extruded aluminum profile needs various surface treatment methods. The commonly used surface treatment methods of aluminum alloy include one anodic oxidation, two electrophoretic coating and three powder spraying. These three methods have different principles, both advantages and disadvantages. The disadvantages of the three methods and the measures to prevent the oxidation corrosion of Series 3 aluminum coil are briefly analyzed as follows:
Disadvantages of three surface treatment methods of Series 3 aluminum coil:
1. Electrophoretic coating: if the electrophoretic coating does not strictly meet the requirements of various processes, such as long baking time, tank liquid pollution, tank liquid composition is not qualified, etc. Aluminum profile surface rough, blistering, pinhole or shrinkage, varnish stains, low gloss, uneven film, profile surface cracks and other surface defects.
2. Anodic oxidation: the oxide film is easy to mix with impurities and turn yellow; The material is easy to stick together, so that the surface oxidation color is uneven, the formation of rainbow color, resulting in poor appearance of the product; Profiles and cold beds tend to form black. K dot or white dot; The temperature of the electrolyte is too high or the electrolyzing time is too long, resulting in the aluminum profile surface. White opaque powder; In the process of oxidation, if the profile drops, it is easy to cause a short circuit; If the concentration of sulfuric acid is not well controlled in the process of alkali corrosion, the corrosion resistance of profile surface will be reduced. Oxide film surface is also prone to blackening or appearance quality problems.
3. Powder coating: if the raw material quality is poor, and mixed with dust or impurities, it will produce particles on the surface of the profile; Dirty compressed air mixed with oil or water can also lead to shrinkage defects on the surface of aluminum profiles; Unreasonable matching will affect the physical properties and chemical resistance of aluminum profile products, such as hardness, impact resistance and bending resistance; This will also result in a poor appearance of the profile surface, no powder and yellowing.
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