Corrosion inhibiting sol-gel coatings for metal alloys

• US 6,579,472 B2
• Filed: 07/27/2001
• Issued: 06/17/2003
• Est. Priority Date: 07/27/2001
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Kendig, Martin W., Chung, Young Jin, Jeanjaquet, Samuel Lee
• Primary Examiner(s): ANTHONY, JOSEPH DAVID
• Application Number:
  US09/917,089
• Publication Number:
  US 20030024432A1
• Time in Patent Office: 690 Days
• Field of Search: 252/389.2, 252/389.23, 252/389.31, 252/389.4, 252/389.41, 252/389.52, 252/389.1, 252/400.2, 252/400.23, 252/400.31, 252/400.4, 252/400.41, 252/400.52, 106/14.05, 106/14.13, 106/14.41, 106/287.19, 106/14.14, 516/99, 516/104, 516/100, 516/117, 501/12, 427/387, 427/435
• US Class Current: 252/389.31
• CPC Class Codes: C08G 77/58 Metal-containing linkages C08G77/485 takes precedence
• CPC Class Codes: C09D 1/00 Coating compositions, e.g. paints, varnishes or lacquers, based on inorganic substances
• CPC Class Codes: C09D 5/08 Anti-corrosive paints
• CPC Class Codes: C23C 18/1204 inorganic material, e.g. non-oxide and non-metallic such as sulfides, nitrides based compounds
• CPC Class Codes: C23C 18/1254 Sol or sol-gel processing
• CPC Class Codes: H05K 3/282 for inhibiting the corrosion of the circuit, e.g. for preserving the solderability
• CPC Class Codes: H05K 3/389 by the use of a coupling agent, e.g. silane
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft

Abstract

An anti-corrosive sol-gel that is a combination of an organometallic salt, an organosilane, and a borate, phosphate, or zinc functional component. The organosilane component may be selected from a large group of equivalent compounds but is preferably an alkoxyzirconium salt, and most preferably Zr (IV) n-propoxide. The organosilane may also be selected from a large group of equivalent compounds, but is preferably 3-glycidoxypropyltrimethoxysilane (GTMS). Combination of the components takes place in the presence of an organic catalyst, preferably acetic acid.

Claims

1. A chromate-free anti-corrosive sol-gel for use in coating metal surfaces which provides an improved adhesion layer for subsequent surface coatings, said treatment comprising:

an organometallic;

an organosilane;

an organic acid; and

,

an anti-corrosion compound having functionality selected from the group consisting of borates, phosphates, zinc, and combinations thereof,

wherein the anti-corrosion compound is present in an amount between about 5 mol % and about 10 mol % with respect to the combined organometallic and organosilane content of the sol-gel.

2. The surface treatment of claim 1 wherein the organometallic is selected from the group consisting of an alkoxyzirconium, yttrium acetate trihydrate, yttrium 2-ethylhexanoate, i-proproxyttrium, methoxyethoxyttrium, yttrium nitrate, cerium acetate hydrate, cerium acetylacetonate hydrate, cerium 2-ethylhexanolate, i-propoxycerium, cerium stearate, cerium nitrate, lanthanum nitrate hexahydrate, lanthanum acetate hydrate, lanthanum acetylacetonate and mixtures thereof.

3. The surface treatment of claim 2 wherein the organosilane is selected from the group consisting of 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimetheoxysilane, p-aminophenylsilane, allyltrimethoxysilane, n-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-glycidoxypropyldiisopropylethoxysilane, (3-glycidoxypropyl)methyldiethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, n-phenylaminopropyltrimethoxysilane, vinylmethyldiethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, and mixtures thereof.

4. The surface treatment of claim 3 wherein the organosilane is 3-Glycidoxypropyltrimethoxysilane (GTMS).

5. The surface treatment of claim 2 wherein the organometallic is an alkoxyzirconium.

6. The surface treatment of claim 5 wherein the alkoxyzirconium is Zr (IV) n-propoxide.

7. The surface treatment of claim 6 wherein the added compound is a phosphate.

8. The surface treatment of claim 6, wherein GTMS and Zr (IV) n-propoxide are present in a molar ratio between about 2:

1 and about 5;

1.

9. The surface treatment of claim 6, wherein the organic acid is acetic acid.

10. The surface treatment of claim 6, wherein the GTMS and Zr (IV) n-propoxide are dissolved in an alcohol.

11. A chromate-free anti-corrosive surface treatment comprising

a) about 7.0 wt % to about 9.0 wt % 3-glycidoxyprophyltrimethoxysilane;

b) about 1.0 wt % to about 3.0 wt % Zr (LV) n-propoxide;

c) about 0.5 wt % to about 1.5 wt % acetic acid;

d) about 2.5 wt % to about 7.5 wt % water;

e) about 77.0 wt % to about 88.2 wt % methanol; and

f) about 0.2 wt % to about 2.0 wt % of a phosphate containing compound.