The Application Of Rare Earth In The Preparation Of The Anodic Oxide Alumina Film

The anodic oxide alumina film had been wide applied in the field of separation, catalysis, optics and so on. Due to rare earth element had the special 4f electron shell, which displayed the chemical characteristic, the article researched the influence of the rare earth ions on the thickness and hardness of the anodic oxide alumina film.The main work of this thesis and conclusions were as follow:1. Preparation technology of the anodic oxidation in the sulfuric acid system were researched.The conditions of the preparation, such as the concentration of sulfuric acid, voltage, temperature, the reaction time, had an influence on the thickness and the hardness of the anodic oxide alumina film. The results showed that the optimum conditions were that with the voltage 20V reacted for 2h, in the 15% sulfuric acid at 15℃. In the optimum conditions, the thickness is 70μm and hardness is 335.5HV.2. Preparation technology of the anodic oxide alumina film with the addition of rare earth ions.The influence of the addition of Pr³⁺, Y³⁺, Nd³⁺, Dy³⁺, Er³⁺, Gd³⁺, on the thickness and hardness of the anodic oxide alumina film was inspected. In this foundation, the conditions of the reaction, such as voltage, temperature, the reaction time were researched. Theconclusions were as follow:1) The optimal concentration of the rare earth ions Pr³⁺, Y³⁺, Nd³⁺, Dy³⁺, Er³⁺, Gd³⁺ adding into the electrolyte bath were 1.0mmol/L, 2.5mmol/L, 2.0mmol/L, 2.0mmol/L, 2.5mmol/L, 1.5mmol/L, respectively. The thickness was 84μm, 80μm, 85μm, 75μm, 82μm, 78μm and the hardness was 355.7HV, 354.4HV, 357.1HV, 353.2HV, 363.0HV, 349.7HV. The thickness and hardness of the anodic oxide alumina film, adding the rare ions, were higher than before.2) The optimum preparation of the anodic oxide alumina film adding Pr³⁺was that in the condition of 1.0mmol/L Pr³⁺ and the voltage of 22V, react 2h in the 15% sulfuric acid at 15℃. The thickness and hardness were 130μm and 310.2HV. The optimum preparation adding Nd³⁺ was that in the condition of 2.0mmol/L Nd³⁺ and the voltage of 22V, react 2h in the 15% sulfuric acid at 15℃. The thickness and hardness were 135μm and 305.4HV. The optimum preparation adding Er³⁺ was that in the condition of 2.5mmol/L Er³⁺ and the voltage of 22V, react 2h in the 15% sulfuric acid at 15℃. The thickness and hardness were 135μm and 306.7HV.3. The time of the corrosion and ultrasonic had an influence on the appearance. The time of the corrosion and ultrasonic was researched. The results showed that after 13min, the role were through mostly, but the anodic oxide alumina film was coated by the floc, what was disappeared by ultrasound for 10min.4. The characterization of the anodic oxide alumina film By scanning electron microscopy (SEM), electron spectroscopy (EDX), X-ray diffraction (XRD), respectively, analyzed the composition and structure of the anodic oxide alumina film. The conclusions were as follow:1) The EDX showed that the anodic oxide alumina film mainly consisted of O and Al, and the atomic ratio of O and Al is nearly 3:2.2) The XRD showed that the anodic oxide alumina film was amorphism. But it was changed intoγ-Al₂O₃ andα-Al₂O₃, processing for 2h respectively at 850℃and 1000℃.At 950℃, the anodic oxide alumina film is changing fromγ-Al₂O₃ toα-Al₂O₃.The innovation of this thesis:In the sulfuric acid system, the addition of Pr³⁺, Y³⁺, Nd³⁺, Dy³⁺, Er³⁺, Gd³⁺ was inspected, which had an influence on the thickness and hardness of the anodic oxide alumina film. With the addition of Pr³⁺, Er³⁺, the preparation technology of the anodic oxide alumina film was researched.