Sacrificial coating and procedure for electroplating aluminum on aluminum alloys

Abstract

A method of applying a protective coating with improved adhesion on an aluminum alloy component includes first pretreating the surface of a component by depositing a sacrificial protective immersion layer using a zincating or similar process. Portions of the protective immersion layer as well as portions of the underlying aluminum alloy substrate are then electrolytically etched off in an ionic liquid. A protective aluminum coating is then electrodeposited on the component in an ionic liquid

1 . A method of applying a protective aluminum coating with improved adhesion on an aluminum alloy component comprising:
 pretreating the surface of the component by depositing a sacrificial protective layer using an immersion coating process;   electrolytically removing portions of or all of the protective layer and portions of the underlying aluminum alloy substrate; and   electrodepositing a protective aluminum coating on the component.   
     
     
         2 . The method of  claim 1 , wherein the protective layer comprises zinc, tin, copper, zirconium, cerium, or combinations thereof. 
     
     
         3 . The method of  claim 1 , wherein the immersion coating process comprises a zincating process. 
     
     
         4 . The method of  claim 1 , wherein the immersion coating process comprises grit blasting, acid etching, desmutting, zincating, rinsing, drying, and combinations thereof to deposit a sacrificial protective layer. 
     
     
         5 . The method of  claim 4 , wherein the thickness of the sacrificial layer is from 20 nm to 3 microns. 
     
     
         6 . The method of  claim 1 , wherein electrolytically removing portions of the protective layer and portions of the underlying aluminum alloy substrate comprises electrolytic etching in an ionic liquid. 
     
     
         7 . The method of  claim 1 , wherein the aluminum alloy component comprises at least one of 6061 alloy, 7075 alloy, and 2024 alloy. 
     
     
         8 . The method of  claim 1 , wherein the protective aluminum coating comprises pure aluminum. 
     
     
         9 . The method of  claim 1 , wherein electrodepositing a protective aluminum coating comprises electrodepositing in an ionic liquid. 
     
     
         10 . The method of  claim 9 , wherein the ionic liquid is 1-ethyl-3-methylimidazolium chloride [EMIM][Cl]-AlCl3 or 1-butyl-3-methylimidizolium chloride [BMIM][CL]-AlCl3. 
     
     
         11 . A coated metal component comprising:
 an aluminum alloy substrate;   an electrodeposited aluminum protective coating on the substrate; and   an uneven interfacial boundary between the aluminum alloy substrate and aluminum protective coating comprising potential remnant portions of an   electrodeposited sacrificial protective layer on the substrate that was produced by an immersion coating process and was subsequently electrolytically etched as well as etched portions of the aluminum alloy substrate.   
     
     
         12 . The coated component of  claim 11 , wherein the aluminum alloy substrate comprises at least one of 6061 alloy, 7075 alloy and 2024 alloy. 
     
     
         13 . The coated component of  claim 11 , wherein the protective aluminum coating comprises pure aluminum. 
     
     
         14 . The coated component of  claim 11 , wherein electrodeposited aluminum protective coating is formed by electrodeposition in an ionic liquid. 
     
     
         15 . The coated component of  claim 14 , wherein the ionic liquid 1-ethyl-3-methylimidazolium chloride [EMIM][Cl]-AlCl3 or 1-butyl-3-methylimidizolium chloride [BMIM][CL]-AlCl3. 
     
     
         16 . The coated component of  claim 11 , wherein the immersion coating process comprises a zincating process. 
     
     
         17 . The coated component of  claim 11 , wherein the zincating process comprises grit blasting, desmutting, zincating, rinsing, drying, and combinations thereof to deposit a sacrificial protective layer. 
     
     
         18 . The coated component of  claim 11 , wherein the sacrificial layer comprises zinc, tin, copper, zirconium, cerium, or combinations thereof. 
     
     
         19 . The coated component of  claim 11 , wherein the protective layer and the etched portions of the aluminum alloy substrate were etched by electrolytic etching in an ionic liquid. 
     
     
         20 . The coated component of  claim 19 , wherein the ionic liquid is 1-ethyl-3-methylimidazolium chloride [EMIM][Cl]-AlCl3 or 1-butyl-3-methylimidizolium chloride [BMIM][CL]-AlCl3.