If there is no aluminum ion in the anodizing solution and the oxidizing film has a strong dissolving ability during anodization, it is difficult to obtain a normal film thickness, and the corrosion resistance and wear resistance of the film layer are also poor. Accumulation of excessive aluminum ions in the anodizing solution will result in a decrease in the concentration of free sulfuric acid and a decrease in the conductivity. When a constant voltage process is adopted, the current density is significantly reduced, resulting in insufficient film thickness, reduced transparency, and even white marks or streaks. Non-uniform phenomena such as traces of other shapes, etc., if the process method of controlling current is used, it will cause voltage increase and increase of electric energy consumption. In severe cases, film burns and blackening after sealing may occur. The limiting concentration of aluminum ions in the anodizing solution is generally controlled within 20-30 g/L, and the suitable concentration is controlled within the range of 3-10 g/L. The obtained oxide film layer has corrosion resistance and abrasion resistance. All better. In view of the relationship between the change of aluminum ion concentration and the quality of the oxide film, the analysis of aluminum ions should be regarded as one of the important contents of maintaining the anodizing solution.
