Effect of neodymium salt in the anodization of aluminum in sulphuric acid

Neodymium salt was used as additives for the first time in preparing anodic aluminum oxide (AAO) films to improve its performance. AAO films were prepared by anodization method from a 15 vol. % sulphuric acid solution containing neodymium salt; the effects of concentration of neodymium on microhardness and thickness of AAO film were researched, respectively. The effect of heat treatment temperature on structure of AAO film was researched. AAO films were characterized by XRD, EDAX and SEM techniques. The microhardness and thickness of AAO film were 377.2HV and 85μm respectively, which were higher 12.60% and 21.43% than those of the film prepared in electrolyte of nothing addition neodymium salt, respectively. The surface of AAO film was smoother and the aperture of AAO film was more uniform than those of films prepared in electrolyte of nothing addition neodymium salt. The apertures of AAO film were in 25∼30nm. There was not neodymium in AAO film. AAO films were amorphous when heat treatment temperatures of AAO film were below 800°C, heat treatment temperature of AAO film were 850°C and 1000°C respectively, AAO films were γ-Al ₂O ₃ and α-Al ₂O ₃ film respectively.