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

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