Chemically resistant anodic oxide films formed on Al–Nd alloy in non-aqueous electrolytes

Chemically resistant oxide films were formed by anodizing of Al–3 wt.% Nd alloy sputtered films in non-aqueous electrolytes that contain ammonium salicylate, ethylene glycol, and ethylene carbonate. The films were hardly etched by a typical etchant for Al thin films, while the films formed in conventional electrolytes were considerably etched. By secondary ion mass spectroscopy and atomic force microscopy, it was revealed that the films had a carbon rich outer layer.