BUCKLING OF ANODIC FILMS ON ALUMINUM - DETERMINATION OF PLASTIC-DEFORMATION ENERGY OF COATINGS

The mechanical instability of oxide layers on anodized aluminum generates a regular arrangement of straight lines parallel to the cylindrical electrode axis. This is analyzed using Euler's equation for buckling of thin cylindrical shells under compressive forces, due to volume expansion concurrent with metal-oxide formation. The coating critical stress is determined as well as the energy dissipated by plastic deformation of the anodic coating. Most of the energy associated with compressive stress of the oxide film is dissipated by plastic deformation.