アルミニウム上へのリチウム塩化成皮膜の作製と増膜処理

Abstract

The study of anodic oxidation of aluminum was carried out for the improvement of corrosion resistance and wear resistance, and for the addition of various kinds of function. In this investigation, the chemical conversion coatings of micron order was studied using a 1%–lithium carbonate bath and a 2%–lithium hydroxide bath. The coatings were analyzed and characterized by secondary ion mass spectrometry, scanning electron microscope and x-ray diffraction instruments. The corrosion resistance and the alkali resistance of the coatings were studied comparing with anodic oxidation coatings and EW method film. The coatings were superior to anodic oxidation coating and EW method film in corrosion resistance. The structure of the chemical conversion coating was comfirmed as α–lithium aluminate and γ–alumina with x-ray diffraction. The film thickness increased by secondary dipping in mixing bath of 2%–sodium silicate and 2%–sodium fluoride. The content of lithium fluoride or aluminum fluoride in the secondary treated film was confirmed by secondary ion mass spectrometry. The fluorine was it uniformly dispersed in secondary film, and lithium silicate was observed not only at the surface but the inside of the film.