Comparative Studies of Anodic Coatings Formed in the METALAST and Traditional Electrolytes (part 1)

As an effort to understand the details of the METALAST anodizing process in terms of its advantages over the traditional anodizing process and the mechanisms of anodizing under the constant current density condition, the comparative study of anodic coatings formed in the METALAST and the traditional electrolytes respectively is being carried out. This report covers the initial results of this comparative study. It includes the results of the chemical dissolution rate of anodic coatings, coating weight, coating ratio, aluminum consumption during anodizing, apparent coating density, and the net weight gain of anodized samples. In order to make this report more understandable, the scientific meanings of these parameters are explained in more detail as following. During anodizing the formed anodic coatings could dissolve in anodizing electrolytes due to the aggressiveness of the acid solution. The consequence of anodic coating dissolution in the anodizing electrolyte is increasing the build-up of aluminum ions in the bath and thus, decreasing the lifetime of the bath. In addition, it may increase the temperature sensibility of the process and decrease the hardness of anodic coatings produced.