13M硫酸溶液中で生成したアノード酸化皮膜の細孔中へのニッケルの電析

抄録

Aluninum was anodized for different durations in a 13M H₂SO₄ solution (20°C) at constant voltages of 30, 35, 40, and 45V. It was possible to deposit nickel uniformly into the pores of the formed oxide without pre-treatment. Electrodeposition did not take place with films formed in dilute H₂SO₄ solutions. The behavior and mechanism of the elecctrodeposition were examined in relation to the film structure and the results are summarized as follows: Film structure-Reanodizing behavior of the specimens in a neutral borate solution suggests that the 13M sulfuric acid films have numerous micro voids in the barrier layer, probably penetrating through the oxide to the substrate metal, and formed as a result of the incorporation of SO₄^2- ions in the oxide and their partial removal during washing of the film with water. Deposition behavior-Electrodeposition was made in two steps in a solution of 70g dm^-3 NiSO₄⋅7H₂O-30g dm^-3H₃BO₃ (20°C), by first applying a small cathodic current of 0.05A·dm^-2 for 15min followed by 1.45A·dm^-2 for 45min. The first step was essential to form nickel nuclei in the micro voids, and a uniform deposit could only be obtained by the two-step procedure. The maximum thickness of the uniform deposit was found to increase with the voltage at which film was formed. The distribution of nickel in the pores and surface of the films was confirmed by XMA.