In recent years, in the aluminum, aluminum-plastic panels and honeycomb panels in the surface treatment technology, there is a tendency to anodic oxidation technology development. For aluminum plate, aluminum plate and honeycomb plate anodizing treatment, should pay attention to the anodic oxide film thickness uniformity, color uniformity and reproducibility. And to ensure the uniformity of the thickness of the anodic oxide film, color uniformity and reproducibility, you must strictly control the chemical composition of aluminum alloy and anodizing production process.
1. Strict control of casting production process. The chemical composition of the ingot must be as small as possible and the chemical composition must be uniform. In addition, the smelting process, casting process and homogenization process must be strictly enforced.
2. Choose the right fixture. The fixture material must be made to ensure good electrical conductivity, the general choice of copper or copper alloy fixture. Has been used for special or general purpose fixtures such as anodizing treatment when used again, must remove its surface oxide film to ensure good contact.
3. Strictly control the anodizing temperature. From the anodic oxidation mechanism, it can be seen that when the anodic oxidation temperature is low, the oxide film is dense and the porosity is small. As the anodic oxidation temperature increases, the oxide film becomes loose and the porosity becomes larger and the color of the film With the temperature gradually deepened. Therefore, the anodic oxidation temperature is an important factor in determining the degree of adhesion of the oxide film, but also an important factor in determining the uniformity of the oxide film.
4. Strictly control the anodic oxidation current density. As the current density increases, the color of the oxide film becomes darker and the thickness of the film increases first and then becomes thinner. The reason is that the current density increases, the film pores are increased, and the color density is reduced. Growth rate is reduced, the film is dense, so as the current density increases, the color of the oxide film gradually deepened. Under the same conditions, increase the current density, increase the growth rate of the oxide film, shorten the oxidation time, reduce the chemical dissolution of the film, the film is hard and the wear resistance is good. But the current density can not rise too high, otherwise it will be due to the impact of Joule heat, film hole thermal effect increases, the local temperature rise significantly, the dissolution rate of the oxide film to accelerate the film rate decreased. That is, the current density increases, in a certain range can increase the rate of film formation, but to a certain value, the film formation rate decreased. The size of the current density directly affects the uniformity of the oxide film color.