WETTING OF ANODIC OXIDE FILMS ON ALUMINUM BY VARIOUS LIQUIDS.

Contact angles between various liquids and different anodic oxide films produced in acid baths (sulfuric and oxalic acids) and alkaline baths (ammonium hydroxide and fluoride mixture, ethylenediamine and ammonium carbonate) were measured. The anodic oxide films formed in the alkaline baths were found to be more wettable by distilled water than those formed in the acid baths but less wettable by oils. The films produced in the alkaline baths were hardly wetted by basic organic solvents and more easily wetted by acid solvents than those produced in the acid baths. Wetting of the films by aqueous solutions dissolving gases was accelerated in accordance with gas concentration probably by a corrosive action of the dissolved gases.