Shortened process for imparting corrosion resistance to aluminum substrates

Abstract

A process for importing corrosion resistance to the surface for an aluminum substrate by contacting the aluminum substrate with an aqueous solution containing at least one of terafluoroboric acid, hexafluorosilisic acid, hexafluorotitanic acid, hexafluorozirconic acid, hexafluorohafnic acid and soluble, partially or totally neutralized salts and vanadate anions.

The invention claimed is:  
     
         1 . A process for imparting corrosion resistance to a surface of an aluminum substrate, which comprises contacting the surface of the aluminum substrate with liquid treatment solution which comprises: water, and 
 (A) 0.1 to 20 mM/Kg of a fluorine containing composition selected from the group consisting of tetrafluoroboric acid, water soluble, partially or totally neutralized salts of tetrafluoroboric acid, hexafluorotitanic acid, water soluble, partially or totally neutralized salts of hexafluorotitanic acid, hexafluorozirconic acid, water soluble, partially or totally neutralized salts of hexafluorozirconic acid, hexafluorohafinic acid, water soluble, partially or totally neutralized salts of hexafluorohafinic acid and mixtures thereof; the concentrations of any salts included in the solution being measured as their stoichiometric equivalent of the corresponding acid; and    (B) from 0.40 to 95 mM/kg. of vanadate anions, measured as its stoichiometric equivalent as vanadium atoms.    
     
     
         2 . The process of  claim 1  wherein the liquid treatment solution contains from 0.55 to 11 mM/kg of the fluorine containing composition.  
     
     
         3 . The process according to  claim 1 , wherein the solution contains from 1.5 to 55 mM/Kg of vanadate anions.  
     
     
         4 . The process of  claim 1  wherein the solution contains from 0.55 to 11 mM/Kg of the fluorine containing composition and from 1.5 to 55 mM/Kg of vanadate anions.  
     
     
         5 . The process of  claim 1  wherein the liquid treatment solution is at a pH of from 0.5 to 5.5.  
     
     
         6 . The process of  claim 5  wherein the pH is from 2.5 to 4.8.  
     
     
         7 . The process of  claim 1  wherein a temperature of the liquid treatment solution is from 30° C. to 95° C.  
     
     
         8 . The process of  claim 7  wherein the temperature of the treatment solution is from 40° C. to 80° C.  
     
     
         9 . The process of  claim 4  wherein a pH of the liquid treatment solution is from 1.0 to 5.0.  
     
     
         10 . The process of  claim 9  wherein the pH of the treatment solution is from 2.0 to 4.6.  
     
     
         11 . The process of  claim 4  wherein the liquid treatment solution is at a temperature of from 30° C. to 95° C.  
     
     
         12 . The process of  claim 5  wherein a temperature of the liquid treatment solution is from 30° C. to 80° C.  
     
     
         13 . The liquid treating solution useful in the process of  claim 1 .  
     
     
         14 . The liquid treating solution of  claim 13  comprising 0.55 to 11 mM/Kg of the fluorine containing composition and 1.5 to 55 mM/Kg of vanadate anions.  
     
     
         15 . The liquid treating solution of  claim 14  having a pH of from 0.5 to 5.5.  
     
     
         16 . The liquid treating solution of  claim 15  wherein the pH is from 2.0 to 4.8.  
     
     
         17 . The process of  claim 1 , in which a visually clean surface of an aluminum substrate is provided with a corrosion resistant surface by the sole step of contacting the aluminum substrate with a liquid treatment solution comprising water; 
 (A) 0.1 to 20 mM/kg of a fluorine containing composition selected from the group consisting of tetrafluoroboric acid, water soluble, partially or totally neutralized salts of tetrafluoroboric acid, hexafluorotitanic acid, water soluble, partially or totally neutralized salts of hexafluorotitanic acid, hexafluorozirconic acid, water soluble, partial or totally neutralized salts of hexafluorozirconic acid, hexafluorohafinic acid, water soluble, partially or totally neutralized salts of hexafluorohafnic acid and mixtures thereof; the concentrations of any salts included in the solution being measured as their stoichiometric equivalent of the corresponding acid; and    (B) from 0.40 to 95 mM/kg. of vanadate anions, measured as its stoichiometric equivalent as vanadium atoms.    
     
     
         18 . The process of  claim 17  wherein the liquid treatment solution is at a pH of 1.0 to 5.5.  
     
     
         19 . The article of manufacture prepared by the process of  claim 1 .  
     
     
         20 . The article of manufacture of  claim 19  wherein the surface of the article is dried directly after contact with the liquid solution to provide a coating containing from 0.1 to 8 mg/m 2  of vanadium.