Thermotreatment and chemical resistance of porous alumina membrane prepared by anodic oxidation

Porous alumina membranes were prepared by anodic oxidation of aluminum in an aqueous solution of oxalic acid. The thermal and chemical stabilities of porous alumina membranes were investigated by thermal analysis and corrosion test. Alumina membranes prepared in oxalic electrolyte had fairly good thermal stability, but they reacted with boiling water to form boehmite, which blocked pores on the surface of the membrane. For acid and alkali resistance, the membranes were estimated to have chemical stability in aqueous acidic and alkaline solution at 1< pH < 12. On the other hand, pore size and its distribution were not changed at the time of thermal treatment. Polycrystalline alumina membrane obtained by thermal treatment for 3 h at 900 ‡C could suppress corrosion reaction and enhance their resistance in acid and alkaline solution.