Abstract
Dyeing affinity, cell size, and cross-section of the anodized films produced in alkaline solutions (0.1M-NaOH, 0.1M-Na2CO3, 0.1M-Na3PO4, and NH4OH-NH4F system bath) were compared with those of the films produced in H2SO4 solution. The surface and cross-section of the thin anodized films which were obtained by complete anodizing of aluminum foils and also the surface of the substrates from which the oxide films had been removed were observed by SEM. The pore walls in the anodized films formed in NaOH and Na3PO4 were uneven compared with those in the films formed in NH4OH-NH4F or H2SO4. Observation of the surface and cross-section of the films prepared in Na3PO4 revealed deposits which seemed to be phosphates or hydroxides. It was found that the bottom size of the cell was linearly proportional to the electrolytic voltage regardless of the bath composition. On the other hand, the differences in permeability, dyeing affinity, and adsorption amount of the dyestuffs (acid, basic, direct and mordant) were determined by mesuring the reflection absorbance of the dyed films and by a colorimetric method. Dyestuffs were adsorbed to a greater extent in the film prepared in Na3PO4 than in any other films produced in alkaline solutions. The amount of the adsorbed dyestuff decreased in the order of the following kinds of films: Na3PO4>NaOH>Na2CO3>NH4OH-NH4F>H2SO4 films. The amount of dyestuff passed through the thin anodized film produced in NH4OH-NH4F was about two times as much as that produced in H2SO4. SEM observation and dyeing tests suggest that the anodized films formed in alkaline solutions have larger pores and cells as compared with the films anodized in H2SO4.
