Underpotential depositon of metal monolayers from ionic liquids

Patent metadata

Field	Value
Publication number	US-9260789-B2
Application number	US-201213470713-A
Country	US
Kind code	B2
Filing date	May 14, 2012
Priority date	May 14, 2012
Publication date	Feb 16, 2016
Grant date	Feb 16, 2016

Abstract

A metal article comprises an alloy substrate having a surface and a non-diffused metal monolayer disposed thereon. The surface has a first surface work function value Φ s . The non-diffused monolayer deposited on the surface has a second surface work function value Φ s that is less negative than the first surface work function value. A method for depositing the monolayer via underpotential deposition (UPD) is also disclosed.

First claim

The invention claimed is:

1. A method for coating a metal article, the method comprising:
providing an alloy substrate;
engineering a surface of the alloy substrate to be coated to have a surface work function value Φ s ;
forming an ionic liquid deposition solution containing a precursor of a depositing species;
depositing a first of a plurality of monolayers via underpotential deposition (UPD) by cathodically reducing the precursor of the depositing species from the ionic liquid deposition solution onto the surface of the alloy substrate, the first of the deposited plurality of monolayers having a depositing work function value Φ d that is less negative than the surface work function value Φ s ; and
increasing a deposition voltage in a stepwise fashion to form subsequent ones of the plurality of monolayers.

2. The method of claim 1 , further comprising
depositing a bulk layer onto the plurality of monolayers.

3. The method of claim 2 , wherein the plurality of monolayers and the bulk layer are both substantially pure aluminum.

4. The method of claim 3 , further comprising after the bulk layer depositing step:
anodizing at least a portion of an outer surface of the bulk aluminum layer.

5. The method of claim 1 , wherein the step of engineering a surface includes increasing surface work function value Φ s by selectively configuring the alloy substrate such that the surface to be coated has a surface work function value Φ s greater than work function values of at least one surface of the alloy substrate that is not to be coated by the monolayer.

6. The method of claim 5 , wherein the alloy substrate has a directionally solidified face centered cubic (FCC) microstructure.

7. The method of claim 6 , wherein the surface to be coated runs substantially along the (100) plane of the FCC microstructure.

8. The method of claim 7 , wherein the alloy substrate includes a majority by weight of aluminum.

9. The method of claim 1 , wherein the step of engineering a surface includes cleaning the surface to be coated in a substantially oxygen-free atmosphere and maintaining the surface to be coated in a substantially oxygen-free atmosphere through the depositing step.

10. The method of claim 1 , wherein the stepwise voltage increase to form a subsequent monolayer occurs after substantially complete deposition of a preceding monolayer.

11. The method of claim 1 , further comprising prior to depositing the first of the plurality of monolayers:
depositing an interlayer onto the surface to be coated.

12. The method of claim 11 , wherein the interlayer has a work function value intermediate between a work function value of the surface to be coated and a work function value of the first monolayer.

13. A method for coating a metal article, the method comprising:
providing an alloy substrate;
engineering a surface of the alloy substrate to be coated to have a surface work function value Φ s ;
forming an ionic liquid deposition solution containing a precursor of a depositing species;
depositing an interlayer onto the surface to be coated; and
depositing a monolayer via underpotential deposition (UPD) by cathodically reducing the precursor of the depositing species from the ionic liquid deposition solution onto the interlayer deposited onto the surface to be coated, the deposited monolayer having a depositing work function value Φ d that is less negative than the surface work function value Φ s .

14. The method of claim 13 , further comprising after the UPD depositing step:
depositing a bulk layer onto the monolayer.

15. The method of claim 14 , wherein the monolayer and the bulk layer are both substantially pure aluminum.

16. The method of claim 14 , further comprising after the bulk layer depositing step:
anodizing at least a portion of an outer surface of the bulk aluminum layer.

17. The method of claim 13 , wherein the step of engineering a surface includes increasing surface work function value Φ s by selectively configuring the alloy substrate such that the surface to be coated has a surface work function value Φ s greater than work function values of at least one surface of the alloy substrate that is not to be coated by the monolayer.

18. The method of claim 17 , wherein the alloy substrate has a directionally solidified face centered cubic (FCC) microstructure.

19. The method of claim 18 , wherein the surface to be coated runs substantially along the (100) plane of the FCC microstructure.

20. The method of claim 18 , wherein the alloy substrate includes a majority by weight of aluminum.

21. The method of claim 13 , wherein the step of engineering a surface includes cleaning the surface to be coated in a substantially oxygen-free atmosphere and maintaining the surface to be coated in a substantially oxygen-free atmosphere through the depositing step.

22. The method of claim 13 , further comprising:
increasing the voltage in a stepwise fashion to form at least one subsequent monolayer by UPD, resulting in a plurality of monolayers.

23. The method of claim 22 , wherein the stepwise voltage increase to form the at least one subsequent monolayer occurs after substantially complete deposition of a preceding monolayer.

24. The method of claim 13 , wherein the interlayer has a work function value intermediate between a work function value of the surface to be coated and a work function value of the monolayer.

Assignees

• Zhang Weilong
• Yu Xiaomei
• Chen Lei
• Jaworowski Mark R
• Sangiovanni Joseph J
• United Technologies Corp

Inventors

• Zhang Weilong
• Yu Xiaomei
• Chen Lei
• Jaworowski Mark R
• Sangiovanni Joseph J

Classifications

• B32B15/01

  all layers being exclusively metallic {(making layered metal workpieces by pressure cladding B23K20/22; making coatings with a metallic material characterised by its composition C23C30/00)} · CPC title

• C23C28/02

  only coatings {only including layers} of metallic material · CPC title

• C25D5/40

  Nickel; Chromium · CPC title

• C25D3/665

  from ionic liquids · CPC title

• C25D5/003

  Electroplating using gases, e.g. pressure influence · CPC title