Anodic Behavior of Aluminum and Its Alloys in Sulfuric Acid Electrolytes

This paper deals with the main factors affecting the rate of solution of anodic oxide coatings on aluminum as they are being formed in sulfuric acid electrolytes. Conditions favoring high coating ratios or thick, hard abrasion‐resistant coatings have been investigated. Low temperatures, high current densities, which permit a shorter time of immersion in the electrolyte, and the addition of substances such as oxalic acid to the electrolyte, favor the formation of such coatings. This has been mainly an investigation of the competition between the rate of formation and the rate of solution of the coatings.