Some properties of aluminum oxide in electrolytic solutions

By anodic oxidation, an aluminum plate can be covered with an amorphous or crystalline oxide layer, depending on the electrolyte used. The amorphous layer, obtained in a solution of oxalic or sulphuric acid, has a porous structure. However, the pores do not go right down to the aluminum as has been shown by many investigators, but end in a solic insulating layer, the thickness of which may be determined by capacity measurements. Corresponding to a given temperature and solic concentration of the electrolytic solution and a given formation current density, there is only one final capacity obtainable. Increasing the concentration, or temperature, or decreasing the current density, increases the final capacity obtainable.Science, Faculty ofPhysics and Astronomy, Department ofGraduat