How to control the concentration of aluminum ions

【China Aluminum Industry Network】In anodizing processes, it's crucial to operate under standard conditions and avoid excessively high current densities or temperatures. If these are not controlled, aluminum ions can accumulate, which may negatively impact the quality of the oxide film formed. To prevent newly prepared anodizing solutions from lacking sufficient aluminum ions—something that could affect the film’s quality—it's recommended to perform partial replacement rather than completely replacing the solution. For example, leaving behind 1/3 or 1/4 of the old solution ensures that the new solution still contains an appropriate concentration of aluminum ions. However, if contamination is severe and a full replacement becomes necessary, there are alternative methods to reintroduce aluminum ions into the solution. One method is power treatment. Before the temperature of the freshly prepared solution drops to the working level, you can conduct anodizing using scrap aluminum pieces or scraps. At higher temperatures, aluminum dissolves more quickly, and this process can typically be completed within 3 to 4 hours, effectively replenishing the aluminum ion content. Another option is to add aluminum powder directly to the solution during preparation. A dosage of 2–3 g/L is usually sufficient to maintain the required aluminum ion concentration and ensure proper film formation. These steps help maintain consistent solution performance and improve the overall quality of the anodized surface.