抄録
Studies were made on the oxide film formed on aluminum by dipping it in 1mol/l LiOH containing NO3-, and the properties of the film were discussed.
It was found that LiOH, NaOH and KOH of 1mol/l had almost the same solvent power for aluminum. However, the solvent power of LiOH was decreased by the addition of nitrates, at which a thick uniform film was formed on the aluminum surface. The film formed by dipping at 70°C for 10min. was about 10μ in thickness and its Hv values measured by micro-vickers hardness tester with 50g load were about 130-190.
A small amount of NH3 was found by analysis in the bath after the formation of film. It was suggested from this fast that NO3-in the bath behaved as an oxidizing agent.
It was supposed by infrared-spectrum that a bonding of Al-OH was evident in the film.
