Dimensional changes of anodized aluminum

摘要

The dimension of an aluminum component usually increases as a result of anodizing. It is generally accepted that the dimensional increase is equal to one third of the thickness of the applied coating after anodized under Type II conditions and one-half of the thickness of the applied coating formed under Type III conditions. The dimensional changes caused by anodizing are affected by a number of variables including the current density, electrolyte concentration and temperature, as well as the thickness of the coating. In this study the dimensional changes of anodized aluminum were investigated under both Type II and Type III conditions as a function of the type of aluminum alloys and differing current densities. The results showed that, although the dimensional changes were different for various aluminum alloys, they were mainly affected by the current density used in the anodizing process, especially under Type II conditions. The data obtained in this study provides design engineers with comprehensive dimensional change information which can help in their tolerance planning.