Coatings and methods for corrosion detection and/or reduction

• US 7,790,225 B1
• Filed: 09/19/2005
• Issued: 09/07/2010
• Est. Priority Date: 09/19/2005
• Status: Active Grant

• Current Assignee: US Government As Represented By The Director National Security Agency
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Li, Wenyan, Calle, Luz M.
• Primary Examiner(s): Meeks; Timothy H
• Assistant Examiner(s): Louie; Mandy C
• Application Number:
  US11/239,445
• Time in Patent Office: 1,814 Days
• Field of Search: 427/8, 428/402.2, 523/205, 523/201
• US Class Current: 427/212
• CPC Class Codes: B05D 2202/00 Metallic substrate
• CPC Class Codes: B05D 5/00 Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
• CPC Class Codes: B05D 5/06 to obtain multicolour or other optical effects B05D5/02 takes precedence
• CPC Class Codes: C08K 9/10 Encapsulated ingredients
• CPC Class Codes: C09D 5/082 characterised by the anti-corrosive pigment
• CPC Class Codes: C09D 5/29 for multicolour effects
• CPC Class Codes: C09D 7/41 Organic pigments; Organic dyes
• CPC Class Codes: C09D 7/48 Stabilisers against degradation by oxygen, light or heat
• CPC Class Codes: C09D 7/65 macromolecular C09D7/41-C09D7/48 take precedence
• CPC Class Codes: C09D 7/70 characterised by shape, e.g. fibres, flakes or microspheres
• CPC Class Codes: Y10T 428/2984 Microcapsule with fluid core [includes liposome]
• CPC Class Codes: Y10T 428/2985 Solid-walled microcapsule from synthetic polymer
• CPC Class Codes: Y10T 428/2987 Addition polymer from unsaturated monomers only
• CPC Class Codes: Y10T 428/2989 Microcapsule with solid core [includes liposome]
• CPC Class Codes: Y10T 428/2991 Coated
• CPC Class Codes: Y10T 428/2998 including synthetic resin or polymer

Abstract

Coatings and methods are provided. An embodiment of the coating includes microcapsules that contain at least one of a corrosion inhibitor, a film-forming compound, and an indicator. The microcapsules are dispersed in a coating vehicle. A shell of each microcapsule breaks down in the presence of an alkaline condition, resulting from corrosion.

Claims

1. A corrosion detection method, comprising:

applying a coating on a metal-containing surface, the coating comprising microcapsules dispersed in a coating vehicle, the microcapsules comprising shells encapsulating an indicator;

breaking down the shells by interaction of the shells and an alkaline condition naturally occurring in the presence of corrosion; and

releasing the indicator.

2. The detection method of claim 1, wherein indicating the presence of corrosion using the indicator comprises the indicator changing color in response to the alkaline condition.

3. The detection method of claim 1, wherein indicating the presence of corrosion using the indicator comprises the indicator fluorescing in response to the alkaline condition.

4. The detection method of claim 1, wherein the coating vehicle is selected from the group consisting of clear paint, clear varnish, opaque varnish, opaque paint, water, solvents, and aqueous gel.

5. A method of treating of a surface, comprising:

applying a coating to the surface, wherein the coating comprises microcapsule shells dispersed in a coating vehicle, the microcapsule shells containing a corrosion inhibitor;

breaking down the microcapsule shells through interaction of the shells and an alkaline condition naturally occurring in the presence of corrosion; and

releasing the corrosion inhibitor.

6. The method of claim 5, wherein the microcapsules further contain an indicator for indicating the presence of corrosion.

7. The method of claim 6, wherein the indicator changes color in the presence of the alkaline condition or fluoresces in the presence of the corrosion.

8. The method of claim 5, wherein the coating vehicle is selected from the group consisting of clear paint, clear varnish, opaque varnish, and opaque paint.

9. The method of claim 5, wherein the microcapsules containing the corrosion inhibitor are first microcapsules, and further comprising releasing an indicator from second microcapsules in response to these second microcapsules being exposed to the alkaline condition.

10. A method, comprising:

applying a coating to a metal-containing surface;

wherein the coating comprises first microcapsules dispersed in a coating vehicle, each first microcapsule comprising a first encapsulant contained in a first shell;

wherein the first shells break down in an alkaline condition that naturally occurs in the presence of corrosion to release the first encapsulant; and

wherein the first encapsulant includes at least one material selected from the group consisting of corrosion indicators, corrosion inhibitors, and film-forming compounds.

11. The method of claim 10 further comprises:

wherein the coating further comprises second microcapsules dispersed in the coating vehicle, each second microcapsule comprising a second encapsulant contained in a second shell;

wherein the second shells break down in an alkaline condition that naturally occurs in the presence of corrosion to release the second encapsulant; and

wherein the second encapsulant is of a different composition than the first encapsulant and includes at least one material selected from the group consisting of corrosion indicators, corrosion inhibitors, and film-forming compounds.

12. The method of claim 10 further comprises:

wherein the coating further comprises second microcapsules dispersed in the coating vehicle, each second microcapsule comprising a second encapsulant contained in a second shell;

wherein the second shells break down in an alkaline condition that naturally occurs in the presence of corrosion to release the second encapsulant; and

wherein the first encapsulant contains a corrosion indicator and the second encapsulant contains a corrosion inhibitor or a film-forming compound or both.

13. The method of claim 10, wherein the metal-containing surface is a bare metal surface or a coated metal surface.

14. The method of claim 10, wherein the metal-containing surface comprises a metal or metal alloy.

15. The method of claim 10 further comprises:

wherein the coating further comprises second microcapsules dispersed in the coating vehicle, each second microcapsule comprising a second encapsulant contained in a second shell;

wherein the second shells break down in an alkaline condition that naturally occurs in the presence of corrosion to release the second encapsulant; and

wherein the first and second shells are the same material.

16. The method of claim 10, wherein the shells break down at pH values of about 8 or above.

17. The method of claim 10, further comprises indicating a presence corrosion or protecting against corrosion or both.