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Reasons for uneven film thickness of anodic oxide film for industrial aluminum profiles
- 2019-10-08-

The temperature of the anodizing solution has an important influence on the uniformity of the film thickness. The high temperature causes the dissolution rate of the anodized film to be accelerated, and the oxide film is thin, and conversely, the oxide film is thick. The anodizing reaction is carried out at a lower temperature. The production is carried out by heat exchange with cold water and the bath. The bath at the upper end of the oxidation tank is passed through the heat exchanger and then pumped back to the oxidation tank to withdraw the bath and the original tank. There is a temperature difference in the liquid. Because the volume of the oxidation tank is relatively large, the circulation of the bath liquid is insufficient, and the distribution of the pump back to the bath is not uniform, which causes a temperature difference in the oxidation bath. Taking the horizontal production line as an example, the film thickness at both ends of the same profile may be different because there is a temperature difference between the two ends of the bath, which may be different from the upper and lower film thickness of the hanging material, which may be due to the temperature difference between the upper and lower sides of the bath.

On several faces of the same industrial aluminum profile, even in the groove, whether the film is uniform or not has a great relationship with the corresponding cathode area. The cathode area is large, so that the current density distributed in each part of the aluminum profile is uniform, and the film thickness is also uniform. In the horizontal line production, the film thickness of the same part of each profile of the hanging material sometimes appears to be low, which is probably because the cathode plate corresponding to the part appears loose or even falls off, which reduces the cathode area. , resulting in a low film thickness.

  In the actual production process, there are other reasons that may cause uneven film thickness of the oxide film, such as poor contact between the clamp and the profile, and the contact area is too small, which may make the oxide film incomplete or oxide-free. In addition, the wide range of sulfuric acid concentration will make the oxide film thickness of different troughs different , and the large change of sulfuric acid concentration will make the k in the empirical formula ( δ=kIt) for calculating the thickness of the oxide film inaccurate, thus obtaining the oxide film. Thickness is also inconsistent. In the production, as long as the above problems are solved one by one, the film thickness of the oxide film can be ensured to be uniform.