Pretreatment before aluminum anodizing is a key link in the entire process. Different pretreatment methods will produce significant differences in the final oxidation effect.
First, mechanical pretreatment such as grinding and polishing. Grinding can remove defects, scratches and oxide layers on the surface of aluminum products, making the surface smooth and smooth. After the finely polished aluminum parts are anodized, the oxide film has better adhesion, the film layer is more uniform, and the appearance can show a delicate texture. Polishing further improves the surface finish and can reduce the roughness of the oxide film surface, making the oxidized aluminum products have a higher gloss. It is often used in the processing of decorative aluminum products that require higher appearance. For example, in the production of high-end aluminum alloy doors and windows, anodizing after polishing pretreatment can make the surface as bright as a mirror, greatly improving the aesthetics and grade of the product.
In terms of chemical pretreatment, alkali washing and pickling are more common. Alkali cleaning is mainly used to remove oil, dirt and natural oxide films on the aluminum surface. It can activate the aluminum surface and facilitate the uniform growth of the oxide film during the subsequent anodization process. The growth rate of the oxide film of aluminum products pretreated by alkali washing is relatively stable and the thickness uniformity is good, which can effectively improve the quality and protective performance of the oxide film. Pickling focuses on removing impurities and slight corrosion products on the aluminum surface, while also adjusting the microstructure of the aluminum surface. In the processing of some aluminum parts that require high corrosion resistance, pickling pretreatment can improve the bonding force between the oxide film and the substrate, so that the oxide film can protect the aluminum substrate more permanently in harsh environments, such as those used in marine environments. Aluminum equipment parts.
There is also electrochemical pretreatment, such as electrochemical polishing. It uses electrolysis to polish the aluminum surface, which can make the aluminum surface smoother at the microscopic level, and the resulting oxide film is denser, more uniform, and has good gloss and transparency. This pretreatment method is often used for aluminum products that have special requirements for optical properties or surface decoration, such as the aluminum alloy casings of some high-end electronic products. After electrochemical polishing pretreatment and anodizing treatment, the surface of the casing is not only beautiful, but also beautiful. Improve the texture and quality image of the product to a certain extent.
Different pretreatment methods have their own advantages and disadvantages in the aluminum anodizing process. In actual production, it is necessary to comprehensively consider various factors such as the use, performance requirements, and cost of aluminum products to select the most suitable pretreatment method to achieve the ideal anode. Oxidation effect to meet the diverse needs for aluminum anodizing products in different fields.
