Process for depositing alumina onto a substrate and alumina regeneration

Claim 1

A process of concurrently depositing and regenerating alumina for physical deposition on a metal substrate consisting essentially of immersing the substrate in a circulating aqueous bath solution of alkali metal aluminate containing about 62 g of Na 2 O per liter and approximately 96 g of Al 2 O 3 per liter; agitating and heating the bath to a temperature of 80° to 100° C., the agitation insuring homogeneity of the bath; maintaining the bath rejuvenated by evaporating the aluminate solution to concentrate the same as to bring the Na 2 O content to 280-290 g per liter, condensing the evaporated water and returning the water condensate to the aluminate bath, heating the concentrated aluminate solution close to to its boiling point and adding alumina to regenerate the same, filtering the regenerated aluminate solution to remove any deposits of impurities and to eliminate any decomposition seeds from the regenerated aluminate solution, adding water in a quantity substantially equivalent to that which has been evaporated and necessary for keeping the concentration of the aluminate solution at 62 g of Na 2 O per liter, and returning the thus regenerated aluminate solution to the original aluminate solution.