Effect of Current Density on the Film Thickness and Structure of Anodic Barrier Films Formed on Aluminum at Low Voltage Region

Abstract

The differences in properties of anodic films formed on aluminum in ammonium adipate solution at low voltage and high voltage were clarified by investigating the relation between current density and the thickness which was evaluated by voltage jump at re-anodizing of anodized specimen. The film thickness formed at constant current density up to 80V decreased with increasing current density. The film thickness had liner relation with log of current density. This liner relation could be ascertained for all the films formed even at low voltages such as 5V when Galvano-static polarization measurement was applied to avoid iR-drop caused by solution resistance. The thickness became the same value after 20 min sustaining of anodizing voltage accompanied by current decay. Furthermore, it was confirmed that the film thickness was determined by final current density during anodizing.