Flux coated brazing sheet

• US 20040009358A1
• Filed: 04/21/2003
• Published: 01/15/2004
• Est. Priority Date: 04/22/2002
• Status: Active Grant

• Current Assignee: American Inks and Coatings Company Incorporated, Arconic Inc. (Howmet Aerospace, Inc.)
• Original Assignee: American Inks and Coatings Company Incorporated
• Inventors: Scott, Darwin H., Scott, Deborah B., Kilmer, Raymond J., Anthony, Robert P., Dougherty, Joseph R.
• Granted Patent: US 7,337,941 B2
• Time in Patent Office: Days
• US Class Current: 428/469
• CPC Class Codes: B23K 35/0233 Sheets, foils B23K35/0244 takes precedence
• CPC Class Codes: B23K 35/0238 layered
• CPC Class Codes: B23K 35/286 Al as the principal constituent
• CPC Class Codes: B23K 35/36 Selection of non-metallic compositions, e.g. coatings, fluxes B23K35/34 takes precedence; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest selection of soldering or welding materials proper B23K35/24
• CPC Class Codes: B23K 35/3605 Fluorides
• CPC Class Codes: B23K 35/3612 with organic compounds as principal constituents
• CPC Class Codes: B23K 35/3613 Polymers, e.g. resins
• CPC Class Codes: B23K 35/365 Selection of non-metallic compositions of coating materials either alone or conjoint with selection of soldering or welding materials

Abstract

A brazing flux mixture comprised of brazing flux, a polyvinyl butyral resin binder, and an organic solvent which can be applied over an entire aluminum alloy brazing sheet, or can be applied on the brazing sheet only where metallurgical bonds or joints are required, that is sufficiently durable to withstand processing operations and also provides good metallurgical bonds upon brazing.

Claims

1. A method of making a flux-coated aluminum brazing sheet comprising:

(a) combining a brazing flux with polyvinyl butyral binder and optionally an organic solvent to form a first mixture;

(b) shearing said first mixture to form a second mixture having uniformly dispersed brazing flux particles in said second mixture;

(c) combining said second mixture with an organic solvent to form a brazing flux mixture;

(d) coating at least a portion of the surface of an aluminum brazing sheet with said brazing flux mixture; and

(e) drying said brazing flux mixture on said aluminum brazing sheet surface.

2. The method of claim 1 wherein said solvent is selected from the group consisting of alcohols, glycol ethers, ketones, esters and mixtures thereof.

3. The method of claim 1 wherein said organic solvent is selected from the group consisting of ethyl acetate, n-butyl acetate, n-propyl acetate, acetone, cyclohexanone, ethyl alcohol, isopropyl alcohol, n-butanol, n-propyl alcohol, diacetone alcohol, dipropylene glycol monomethyl ether, propylene glycol methyl ether acetate and mixtures thereof.

4. The method of claim 1 wherein said organic solvent is a selected from the group consisting of toluene mixed with at least one alcohol selected from the group consisting of ethyl alcohol, isopropyl alcohol, n-butanol, n-propyl alcohol, and diacetone alcohol.

5. The method of claim 1 wherein said solvent is a mixture of either propylene glycol methyl ether acetate, isopropyl alcohol and ethyl acetate;

or dipropylene monomethyl glycol ether, isopropyl alcohol and ethyl acetate.

6. The method of claim 1 wherein said brazing flux is a potassium fluoroaluminate, a cesium potassium fluoroaluminate, a zinc potassium fluoroaluminate, or a silicon and potassium fluoroaluminate mixture.

7. The method of claim 1 wherein said aluminum brazing sheet comprises a 3XXX, 5XXX, or 6XXX aluminum core alloy clad on at least one side with a 4XXX series brazing alloy.

8. The method of claim 1 wherein said aluminum brazing sheet comprises a 3XXX aluminum core alloy comprising about 1 wt. % manganese, about 0.3 wt. % copper, and about 0.15 wt. % titanium, and the balance aluminum, said core alloy clad with a 4XXX aluminum braze alloy comprising about 10 wt. % silicon, and the balance aluminum, and wherein said 4XXX alloy is clad to at least one side of said 3XXX series alloy, and said 4XXX series alloy comprises at least 5% of said total brazing sheet thickness, and said 3XXX series alloy comprises not more than 95% of said total brazing sheet thickness.

9. A method of making a brazing flux mixture comprising:

(a) combining a brazing flux with a polyvinyl butyral binder to form a first mixture;

(b) shearing said first mixture to form a second mixture having uniformly dispersed brazing flux in said binder; and

(c) combining said second mixture with an organic solvent to form a brazing flux mixture.

10. The method of claim 9 wherein said brazing flux is potassium fluoroaluminate, a cesium potassium fluoroaluminate, a zinc potassium fluoroaluminate, or a silicon and potassium fluoroaluminate mixture.

11. The method of claim 9 wherein said solvent is selected from the group consisting of alcohols, glycol ethers, ketones, esters and mixtures thereof.

12. The method of claim 9 wherein said organic solvent is selected from the group consisting of ethyl acetate, n-butyl acetate, n-propyl acetate, acetone, cyclohexanone, ethyl alcohol, isopropyl alcohol, n-butanol, n-propyl alcohol, diacetone alcohol, dipropylene glycol monomethyl ether, propylene glycol methyl ether acetate and mixtures thereof.

13. The method of claim 9 wherein said organic solvent is a selected from the group consisting of toluene mixed with at least one alcohol selected from the group consisting of ethyl alcohol, isopropyl alcohol, n-butanol, n-propyl alcohol, and diacetone alcohol.

14. The method of claim 9 wherein said solvent is a mixture of either propylene glycol methyl ether acetate, isopropyl alcohol and ethyl acetate;

or dipropylene monomethyl glycol ether, isopropyl alcohol and ethyl acetate.

15. An unformed aluminum alloy brazing sheet product, having at least a portion of said sheet surface coated with a brazing flux compound comprising brazing flux and polyvinyl butyral.

16. The aluminum alloy brazing sheet product of claim 15 wherein said portion of said sheet surface coated with a brazing flux compound is coated with from about 2 to about 40 grams of brazing flux compound per square meter of said coated portion of said brazing sheet product.

17. The aluminum alloy brazing sheet product of claim 15 wherein said portion of said sheet surface coated with a brazing flux compound is coated with from about 3 to about 20 grams of brazing flux compound per square meter of said coated portion of said brazing sheet product.

18. The aluminum alloy brazing sheet product of claim 15 wherein said portion of said sheet surface coated with a brazing flux compound is coated with from about 3 to about 10 grams of brazing flux compound per square meter of said coated portion of said brazing sheet product.

19. A method of making a shaped metal alloy product comprising:

(a) combining a brazing flux with polyvinyl butyral binder and optionally an organic solvent to form a first mixture;

(b) shearing said first mixture to form a second mixture having uniformly dispersed brazing flux particles in said second mixture;

(c) combining said second mixture with an organic solvent to form a brazing flux mixture;

(d) coating at least a portion of the surface of at least two aluminum alloy brazing sheets with said brazing flux mixture;

(e) drying said brazing flux mixture on said aluminum alloy brazing sheet surfaces;

(f) forming said flux coated aluminum alloy brazing sheets into flux coated parts having predetermined shapes; and

(g) brazing said parts together to form a shaped metal alloy product.

20. A brazing flux mixture for coating brazing sheet prior to sheet formation into a shaped product, said mixture comprising:

(a) brazing flux;

(b) a polyvinyl butyral resin binder; and

(c) an organic solvent selected from the group consisting of ethyl acetate, n-butyl acetate, n-propyl acetate, acetone, cyclohexanone, ethyl alcohol, isopropyl alcohol, n-butanol, n-propyl alcohol, diacetone alcohol, dipropylene glycol monomethyl ether, propylene glycol methyl ether acetate and mixtures thereof.

21. The brazing flux mixture of claim 20 comprising:

(a) about 35-65 wt. % potassium fluoroaluminate flux;

(b) about 2-11 wt. % polyvinyl butyral resin binder; and

(c) the balance to 100 wt. % of organic solvent.

22. The brazing flux mixture of claim 21 comprising:

(a) about 47-62 wt. % potassium fluoroaluminate flux;

(b) about 5-7 wt. % polyvinyl butyral resin binder; and

(c) the balance to 100 wt. % of organic solvent.

23. The brazing flux mixture of claim 21 comprising from about 40-70 wt. % solvent and from about 30-60 wt. % flux and polyvinyl butyral resin binder.

24. The brazing flux mixture of claim 21 wherein the range of ratios of flux to binder is from about 95 wt. % flux to about 5 wt. % binder to about 85 wt. % flux to about 15 wt % binder.

25. The brazing flux mixture of claim 21 further comprising a pigment.