Thermal phenomena during anodizing of aluminium in sulfuric acid

The heat developing at the oxide-aluminium interface during anodizing in sulfuric acid has been measured. The temperature of the aluminium anode increases rapidly to attain a steady value after a few minutes, and drops sharply upon current interruption. The rise in temperature increases linearly with the current density. The effects of the concentration and temperature of the electrolyte and the anodizing voltage on the heat developed in aluminium have been examined. The results are discussed with regard to the dispute concerning the conditions necessary at the base of the pores for the relatively high local dissolution.