Multilayer, corrosion-resistant finish and method

• US 7,144,637 B2
• Filed: 07/12/2004
• Issued: 12/05/2006
• Est. Priority Date: 07/12/2004
• Status: Active Grant

• Current Assignee: Kurt J. Thomae
• Original Assignee: Kurt J. Thomae
• Inventors: Thomae, Kurt J.
• Primary Examiner(s): Zimmerman, John J.
• Application Number:
  US10/889,594
• Publication Number:
  US 20060008668A1
• Time in Patent Office: 876 Days
• Field of Search: 428/626, 428/628, 428/658, 428/659, 428/421, 428/422, 428/472.3, 428/935, 148/253, 148/254, 205/244, 205/245, 205/309
• US Class Current: 428/626
• CPC Class Codes: B05D 5/083 involving the use of fluoropolymers
• CPC Class Codes: B05D 7/14 to metal, e.g. car bodies involving a chemical reaction between the metal and the coating C23
• CPC Class Codes: B05D 7/51 One specific pretreatment, e.g. phosphatation, chromatation, in combination with one specific coating pretreatment of metallic substrates C23C; pretreatment before coating in general B05D3/00
• CPC Class Codes: B05D 7/52 Two layers
• CPC Class Codes: B05D 7/56 Three layers or more
• CPC Class Codes: C23C 22/73 characterised by the process
• CPC Class Codes: C23C 22/83 Chemical after-treatment
• CPC Class Codes: C25D 3/565 containing more than 50% by weight of zinc
• CPC Class Codes: C25D 5/48 After-treatment of electroplated surfaces
• CPC Class Codes: Y10S 428/935 Electroplating
• CPC Class Codes: Y10T 428/12493 Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
• CPC Class Codes: Y10T 428/12535 with additional, spatially distinct nonmetal component
• CPC Class Codes: Y10T 428/12569 Synthetic resin
• CPC Class Codes: Y10T 428/12611 Oxide-containing component
• CPC Class Codes: Y10T 428/12799 Next to Fe-base component [e.g., galvanized]

Abstract

The present invention provides a black, chrome-free, multilayer corrosion protection finish designed to meet extended corrosion properties. This corrosion-resistant finish is engineered to meet a minimum of 500 salt spray testing hours to white corrosion, and 1500 salt spray testing hours to red corrosion when tested to ASTM B117 standards. It is also designed to comply with the European Union Directive on End of Life Vehicles. This multilayer system is designed for use on automotive body sheet steel, automotive underbody parts, automotive under-hood parts, and some automotive interior parts specifying a gloss requirement greater than 4. This chrome-free, multilayer finish is a combination of a zinc-iron electroplated substrate, a non-electrolytic phosphate crystal conversion layer using orthophosphoric acid, and a Xylan/Teflon fluorocarbon sealer coating to form a three layer total corrosion protection system.

Claims

1. A black, chrome-free, multilayer, corrosion-resistant finish, the corrosion-resistant finish for application to a metal substrate, the corrosion-resistant finish comprising at least three layers, the three layers including:

a zinc-iron substrate layer, the zinc-iron substrate layer being electroplated to a select substrate, the zinc-iron substrate layer being electroplated to the select substrate from a select, non-cyanide, alkaline-based electroplating process;

a phosphate crystal conversion layer, the phosphate crystal conversion layer being non-electrolytic and formed upon the zinc-iron substrate layer using an orthophosphoric acid bath, the zinc-iron substrate layer and the phosphate crystal conversion layer thus forming a zinc-iron-phosphate-crystal substrate; and

a select sealer coating layer, the select sealer coating layer being black in color and chrome-free, the select sealer coating layer coating the zinc-iron-phosphate-crystal substrate, the coated zinc-iron-phosphate-crystal substrate thus forming the multilayer, corrosion-resistant finish.

2. The corrosion-resistant finish of claim 1 wherein the select non-cyanide, alkaline-based electroplating process is selected from a method group, the method group consisting of a first non-cyanide, alkaline zinc-iron alloy plating method, a second non-cyanide, alkaline zinc-iron alloy plating method, and a third non-cyanide, alkaline zinc-iron alloy plating method.

3. The corrosion-resistant finish of claim 1 wherein the select substrate is selected from the group consisting of a metal substrate and a zinc layer, the zinc layer being electroplated to the metal substrate, the zinc layer for providing a stronger bond to the metal substrate for the zinc-iron substrate layer.

4. The corrosion-resistant finish of claim 1 wherein the select sealer coating layer is selected from a coating group, the coating group consisting of a first select fluorocarbon layer and a second select fluorocarbon layer.

5. The corrosion-resistant finish of claim 4 wherein the first select layer comprises polytetrafluoroethylene and a resin polymer binder, the resin polymer binder for aiding fluorocarbon sealer coating layer adhesion to the zinc-iron-phosphate-crystal substrate and to promote corrosion resistance.

6. The corrosion-resistant finish of claim 4 wherein the second select fluorocarbon layer comprises a blend of fluorocarbon lubricants, the blend of fluorocarbon lubricants being bound by an organic resin and solvent system.

7. The corrosion-resistant finish of claim 5 wherein the first select fluorocarbon sealer layer comprises a plurality of thermo-cured coats.

8. The corrosion-resistant finish of claim 1 wherein the metal substrate is cleaned before the zinc-iron substrate layer is electroplated to the metal substrate.

9. The multilayer corrosion-resistant finish of claim 8 wherein the metal substrate is cleaned by a cleaning process, the cleaning process comprising the steps of:

a. soaking the metal substrate in a soak chemical;

b. electro-cleaning the metal substrate;

c. initially rinsing the metal substrate with a rinse compound;

d. acid-cleaning the metal substrate; and

e. finally rinsing the metal substrate with the rinse compound.

10. A multilayer, corrosion-resistant finish, the corrosion-resistant finish comprising:

a zinc-iron substrate layer, the zinc-iron substrate layer for electroplated attachment to a metal substrate, the zinc-iron substrate layer being formed from a select non-cyanide, alkaline-based electroplating process;

a phosphate crystal conversion layer, the phosphate crystal conversion layer being formed upon the zinc-iron substrate layer, the zinc-iron substrate layer and the phosphate crystal conversion layer thus forming a zinc-iron-phosphate-crystal substrate; and

a select sealer coating layer, the select sealer coating layer coating the zinc-iron-phosphate-crystal substrate, the coated zinc-iron-phosphate-crystal substrate thus forming the multilayer, corrosion-resistant finish.

11. The multilayer corrosion-resistant finish of claim 10 wherein the select sealer coating layer is black in color and chrome-free.

12. The multilayer corrosion-resistant finish of claim 10 wherein the select non-cyanide, alkaline-based electroplating process is selected from a method group, the method group consisting of a first non-cyanide, alkaline zinc-iron alloy plating method, a second non-cyanide, alkaline zinc-iron alloy plating method, and a third non-cyanide, alkaline zinc-iron alloy plating method.

13. The corrosion-resistant finish of claim 10 wherein the select substrate is selected from the group consisting of a metal substrate and a zinc layer, the zinc layer being electroplated to the metal substrate, the zinc layer for providing a stronger bond to the metal substrate for the zinc-iron substrate layer.

14. The multilayer corrosion-resistant finish of claim 10 wherein the select sealer coating layer is selected from a coating group, the coating group consisting of a first select fluorocarbon layer and a second select fluorocarbon layer.

15. The multilayer corrosion-resistant finish of claim 14 wherein the first select fluorocarbon layer comprises polytetrafluoroethylene and the second select fluorocarbon layer comprises a blend of fluorocarbon lubricants bound by an organic resin and solvent system.

16. The multilayer corrosion-resistant finish of claim 15 wherein the first select fluorocarbon sealer layer comprises a plurality of coats.

17. The multilayer corrosion-resistant finish of claim 10 wherein the metal substrate is cleaned before the zinc-iron substrate layer is electroplated to the metal substrate.

18. The multilayer corrosion-resistant finish of claim 17 wherein the metal substrate is cleaned by a cleaning process, the cleaning process comprising the steps of:

a. soaking the metal substrate in a soak chemical;

b. electro-cleaning the metal substrate;

c. initially rinsing the metal substrate with a rinse compound;

d. acid-cleaning the metal substrate; and

e. finally rinsing the metal substrate with the rinse compound.

19. A method of applying a multilayer, corrosion-resistant finish to a metal substrate, the method comprising the steps of:

electroplating a zinc-iron substrate layer upon the metal substrate via a select non-cyanide, alkaline-based electroplating process thus forming a zinc-iron-enveloped substrate;

bathing the zinc-iron-enveloped substrate in an orthophosphoric acid bath, the orthophosphoric acid bath forming a phosphate crystal conversion layer upon the zinc-iron-enveloped substrate, the phosphate crystal conversion layer thus forming a zinc-iron-phosphate-crystal-enveloped substrate; and

coating the zinc-iron-phosphate-crystal-enveloped substrate with a select sealer coating layer.

20. The method of claim 19 wherein the metal substrate is cleaned before being electroplated with the zinc-iron substrate layer.

21. The method of claim 20 wherein the metal substrate is cleaned by a cleaning process, the cleaning process comprising the steps of:

a. soaking the metal substrate in a soak chemical;

b. electro-cleaning the metal substrate;

c. initially rinsing the metal substrate with a rinse compound;

d. acid-cleaning the metal substrate; and

e. finally rinsing the metal substrate with the rinse compound.

22. The method of claim 19 wherein a zinc layer is electroplated to the metal substrate before the zinc-iron substrate layer is electroplated to the metal substrate, the zinc layer for providing a stronger bond to the metal substrate for the zinc-iron substrate layer.

23. The method of claim 19 wherein the select non-cyanide, alkaline-based electroplating process is selected from a method group, the method group consisting of a first non-cyanide, alkaline zinc-iron alloy plating method, a second non-cyanide, alkaline zinc-iron alloy plating method, and a third non-cyanide, alkaline zinc-iron alloy plating method.

24. The method of claim 19 wherein the select sealer coating layer is selected from a coating group, the coating group consisting of a first select fluorocarbon layer and a second select fluorocarbon layer.

25. The method of claim 24 wherein the select fluorocarbon sealer coating layer is black in color and chrome-free.

26. The method of claim 24 wherein the first select fluorocarbon layer comprises polytetrafluoroethylene and the second select fluorocarbon layer comprises a blend of fluorocarbon lubricants bound by an organic resin and solvent system.

27. The method of claim 24 wherein the first select fluorocarbon sealer layer comprises a plurality of coats.