Sacrificial coating and procedure for electroplating aluminum on aluminum alloys

Patent metadata

Field	Value
Publication number	US-11401619-B2
Application number	US-201815977698-A
Country	US
Kind code	B2
Filing date	May 11, 2018
Priority date	Mar 15, 2013
Publication date	Aug 2, 2022
Grant date	Aug 2, 2022

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.

First claim

The invention claimed is:

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 sacrificial protective layer and portions of the underlying aluminum alloy substrate by electrolytic etching in an ionic liquid to form a roughened surface of the component, wherein the roughened surface is formed by:
removing all of the sacrificial protective layer and portions of the underlying aluminum alloy substrate to create depressions in the surface of the component in second selected areas; or
removing portions of the sacrificial protective layer so as to leave protruding islands of the sacrificial protective layer over the surface of the component in first selected areas and removing portions of the underlying aluminum alloy substrate to create depressions in the surface of the component in second selected areas; and
electrodepositing a protective aluminum coating on the roughened surface of the component.

2. The method of claim 1 , wherein the sacrificial 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, or combinations thereof to deposit the sacrificial protective layer.

5. The method of claim 4 , wherein the thickness of the sacrificial protective layer is from 20 nm to 3 microns.

6. The method of claim 1 , wherein the aluminum alloy component comprises at least one of 6061 alloy, 7075 alloy, and 2024 alloy.

7. The method of claim 1 , wherein the protective aluminum coating consists essentially of aluminum.

8. The method of claim 1 , wherein electrodepositing the protective aluminum coating comprises electrodepositing in an ionic liquid.

9. The method of claim 1 , wherein the ionic liquid is 1-ethyl-3-methylimidazolium chloride [EMIM][Cl]—AlCl3 or 1-butyl-3-methylimidizolium chloride [BMIM][CL]-AlCl3.

Assignees

• United Technologies Corp

Inventors

• Chen Lei
• Yu Xiaomei
• Jaworowski Mark R

Classifications

• C25D3/665 Primary

  from ionic liquids · CPC title

• C23C18/54

  Contact plating, i.e. electroless electrochemical plating · CPC title

• C25D5/44

  Aluminium · CPC title

• C25F5/00

  Electrolytic stripping of metallic layers or coatings · CPC title

• C23C18/1653

  Two or more layers with at least one layer obtained by electroless plating and one layer obtained by electroplating · CPC title