Oil-impregnated nanoporous oxide coating for inhibiting aluminum corrosion

Abstract

A process includes means for depositing an anti-corrosion coating filled with liquid oil on an aluminum substrate. Aluminum is anodized and then treated with a thin hydrophobic sub-coating. The pores created through anodization are then impregnated with liquid oil. Oil penetration is maximized and residual air is minimized by first filling the pores with a filling solution, replacing the filling solution with an exchange fluid, and then replacing the exchange fluid with perfluorinated oil. The oil gives the surface coating anti-wetting properties and self-healing properties, thereby protecting the aluminum substrate underneath from corrosion.

1 - 27 . (canceled) 
     
     
         28 . A coating for aluminum surfaces, comprising an aluminum oxide layer, including a plurality of high-aspect-ratio, dead-end nanopores distributed throughout said aluminum oxide layer such that each nanopore of said plurality of nanopores has walls extending into said aluminum oxide layer and exhibiting hydrophobic properties, and each nanopore of said plurality of nanopores contains a quantity of liquid oil sufficient to eliminate air therefrom such that said plurality of nanopores contains only said liquid oil which completely fills each nanopore of said plurality of nanopores to thereby eliminate air voids therein. 
     
     
         29 . The coating of  claim 28 , wherein said liquid oil is water-repellant. 
     
     
         30 . The coating of  claim 28  wherein said liquid oil is water immiscible. 
     
     
         31 . The coating of  claim 28 , wherein said liquid oil is anti-corrosive. 
     
     
         32 . The coating of  claim 28 , wherein said liquid oil is a perfluorinated oil. 
     
     
         33 . The coating of  claim 28 , wherein said aluminum oxide layer has an outer surface, such that each nanopore of said plurality of nanopores is isolated from every other nanopore of said plurality of nanopores by said aluminum oxide layer, including said outer surface thereof. 
     
     
         34 . The coating of  claim 33 , wherein said outer surface of said aluminum oxide layer has hydrophobic properties. 
     
     
         35 . The coating of  claim 28 , further comprising a hydrophobic coating provided on said walls of each nanopore of said plurality of nanopores. 
     
     
         36 . The coating of  claim 35 , wherein said liquid oil is capable of filling surface defects in said hydrophobic coating. 
     
     
         37 . The coating of  claim 35 , wherein said hydrophobic coating comprises polytetrafluoroethylene. 
     
     
         38 . The coating of  claim 28 , wherein said walls of each nanopore of said plurality of nanopores include a sidewall and a dead-end, said sidewall cooperating with said dead-end to define a lumen within each nanopore of said plurality of nanopores. 
     
     
         39 . In combination, an aluminum substrate having an aluminum oxide layer which is exposable to corrosive media, said aluminum oxide layer having an outer surface including a plurality of high-aspect-ratio, dead-end nanopores distributed throughout said aluminum oxide layer such that each nanopore of said plurality of nanopores is isolated from every other nanopore of said plurality of nanopores by said aluminum oxide layer, including said outer surface thereof, each nanopore of said plurality of nanopores having a sidewall extending into said aluminum oxide layer from said outer surface thereof; an inner coating of a hydrophobic material applied to said sidewall of each nanopore of said plurality of nanopores and to said outer surface of said aluminum oxide layer; and an outer coating of a liquid oil applied to said plurality of nanopores over said hydrophobic material of said inner coating, said liquid oil of said outer coating completely filling each nanopore of said plurality of nanopores and completely covering said outer surface of said aluminum oxide layer of said aluminum substrate, thereby inhibiting the exposure of said aluminum oxide layer and hence said aluminum substrate to corrosive media. 
     
     
         40 . The combination of  claim 39 , wherein said liquid oil is water-repellant. 
     
     
         41 . The combination of  claim 39 , wherein said liquid oil is water immiscible. 
     
     
         42 . The combination of  claim 39 , wherein said liquid oil is anti-corrosive. 
     
     
         43 . The combination of  claim 39 , wherein said liquid oil is a perfluorinated oil. 
     
     
         44 . The combination of  claim 39 , wherein said liquid oil fills surface defects in said inner coating. 
     
     
         45 . The combination of  claim 39 , wherein said sidewall and dead-end of each nanopore of said plurality of nanopores cooperate to define a lumen within each nanopore of said plurality of nanopores. 
     
     
         46 . The combination of  claim 45 , wherein said liquid oil completely fills said lumen of each nanopore of said plurality of nanopores. 
     
     
         47 . The combination of  claim 39 , wherein said hydrophobic material comprises polytetrafluoroethylene.