Method for deposition of steel protective coating

• US 7,803,428 B1
• Filed: 05/28/2008
• Issued: 09/28/2010
• Est. Priority Date: 03/03/2005
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Archer, Harry L. Jr., Powell, Wayne J., Menke, Josephs T.
• Primary Examiner(s): TUROCY, DAVID P
• Application Number:
  US12/214,296
• Time in Patent Office: 853 Days
• Field of Search: 427/327, 427/328
• US Class Current: 427/328
• CPC Class Codes: C23C 22/34 containing fluorides or complex fluorides
• CPC Class Codes: C23C 22/73 characterised by the process
• CPC Class Codes: C23C 22/83 Chemical after-treatment
• CPC Class Codes: C23C 2222/10 Use of solutions containing trivalent chromium but free of hexavalent chromium
• CPC Class Codes: C23C 28/00 Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
• CPC Class Codes: C23C 28/021 including at least one metal alloy layer
• CPC Class Codes: Y10T 428/12549 Adjacent to each other
• CPC Class Codes: Y10T 428/12611 Oxide-containing component
• CPC Class Codes: Y10T 428/12799 Next to Fe-base component [e.g., galvanized]
• CPC Class Codes: Y10T 428/12937 Co- or Ni-base component next to Fe-base component

Abstract

A method is provided for coating a steel surface of a workpiece. According to an aspect of the invention, a steel workpiece is subjected to a first embrittlement-relief baking operation to form a protective oxide layer on the steel surface. The protective oxide layer is de-scaled, and the steel surface is activated. A hydrogen bather coating is deposited on the activated steel surface, and activated. A zinc-nickel alloy is plated on the barrier coating, and subjected to a second embrittlement-relief baking operation. The porous plating is sealed with a conversion coat. The method is especially useful in making low to no hydrogen embrittlement cadmium-replacement steel parts. Also provided is a corrosion resistant coated steel workpiece.

Claims

1. A method for coating a steel surface of a workpiece, comprising:

subjecting a workpiece comprising a steel surface to a first embrittlement-relief baking operation to form a protective oxide layer on the steel surface;

de-scaling the protective oxide layer from the steel surface;

activating the steel surface;

depositing a hydrogen barrier coating on the activated steel surface to a thickness not greater than about 2.54 microns;

activating the hydrogen barrier coating to form an activated hydrogen barrier coating;

plating a zinc-nickel alloy layer on the activated hydrogen barrier coating to form a porous plate, the zinc-nickel alloy layer comprising about 85 weight percent to about 95 weight percent zinc and about 5 weight percent to about 15 weight percent nickel;

subjecting zinc-nickel porous plate to a second embrittlement-relief baking operation in a substantially inert atmosphere; and

sealing the zinc-nickel porous plate with zinc phosphate and trivalent chromate.

2. A method according to claim 1, wherein the hydrogen barrier coating comprises a nickel-phosphorus coating.

3. A method according to claim 1, wherein the thickness of the hydrogen barrier coating is in a predetermined range of about 1.27 microns to about 2.54 microns.

4. A method according to claim 3, wherein the zinc-nickel alloy layer comprises about 85 to about 91 weight percent zinc and about 9 to about 15 weight percent nickel, and wherein the conversion coat comprises trivalent chromate.

5. A method according to claim 3, wherein the zinc-nickel alloy layer comprises about 93 to about 95 weight percent zinc and about 5 to about 7 weight percent nickel, and wherein the conversion coat comprises zinc phosphate.

6. The method according to claim 1, wherein said first-embrittlement-relief baking operation is performed in a predetermined range of about 130°

C. to about 230°

C.

7. The method according to claim 1, wherein said zinc-nickel porous plate comprises a zinc-nickel alloy with a predetermined plating thickness in a range of about 7.62 microns to about 25.4 microns.

8. A method for coating a steel surface of a workpiece, comprising:

subjecting a workpiece comprising a steel surface to a first embrittlement-relief baking operation to form a protective oxide layer on the steel surface;

de-scaling the protective oxide layer from the steel surface;

subjecting the steel surface to a first rinsing operation without water-break in accordance with ASTM F22;

activating the steel surface;

subjecting the steel surface to a second rinsing operation without water-break in accordance with ASTM F22;

applying a hydrogen barrier coating to the activated steel surface to a thickness not greater than about 2.54 microns;

subjecting the hydrogen barrier coating to a third rinsing operation without water-break in accordance with ASTM F22;

activating the hydrogen barrier coating to form an activated hydrogen barrier coating;

subjecting the activated hydrogen barrier coating to a fourth rinsing operation without a water-break in accordance with ASTM F22;

plating a zinc-nickel alloy layer on the activated hydrogen barrier coating to form a zinc-nickel porous plate, the zinc-nickel alloy layer comprising about 93 weight percent to about 95 weight percent zinc and about 5 weight percent to about 7 weight percent nickel;

subjecting the zinc-nickel porous plate to a fifth rinsing operation;

subjecting zinc-nickel porous plate to a second embrittlement-relief baking operation in a substantially inert atmosphere;

sealing the zinc-nickel porous plate with zinc phosphate and trivalent chromate.

9. The method according to claim 8, further comprising stripping cadmium and paint from the steel surface prior to the first embrittlement relief baking operation.

10. The method according to claim 8, wherein the hydrogen barrier coating comprises a nickel-phosphorus coating.

11. The method according to claim 8, wherein the thickness of the hydrogen barrier layer is in a predetermined range of about 1.27 microns to about 2.54 microns.