BRAZING SHEET PRODUCT AND METHOD OF ITS MANUFACTURE

• US 20020037425A1
• Filed: 05/19/2000
• Published: 03/28/2002
• Est. Priority Date: 05/21/1999
• Status: Active Grant

• Current Assignee: Corus Aluminium Walzprodukte GmbH
• Original Assignee: Corus Aluminium Walzprodukte GmbH
• Inventors: Wittebrood, Adrianus Jacobus, Wijenberg, Jacques Hubert Olga Joseph, Mooij, Joop Nicolaas
• Granted Patent: US 6,379,818 B1
• Time in Patent Office: Days
• US Class Current: 428/652
• CPC Class Codes: B23K 35/002 at least one of the workpieces being of light metal
• CPC Class Codes: B23K 35/0238 layered
• CPC Class Codes: B23K 35/286 Al as the principal constituent
• CPC Class Codes: C25D 5/12 at least one layer being of nickel or chromium
• CPC Class Codes: C25D 5/44 Aluminium
• CPC Class Codes: C25D 5/611 Smooth layers
• CPC Class Codes: C25D 5/627 Electroplating characterised by the visual appearance of the layers, e.g. colour, brightness or mat appearance
• CPC Class Codes: Y10S 428/935 Electroplating
• CPC Class Codes: Y10T 428/12722 Next to Group VIII metal-base component
• CPC Class Codes: Y10T 428/12736 Al-base component
• CPC Class Codes: Y10T 428/1275 Next to Group VIII or IB metal-base component
• CPC Class Codes: Y10T 428/12792 Zn-base component
• CPC Class Codes: Y10T 428/12944 Ni-base component

Abstract

A brazing sheet product and a method of manufacturing a brazing sheet product in which a layer comprising nickel is plated onto a surface of a clad layer made of an aluminium-silicon alloy containing silicon in the range of 2 to 18 weight %, wherein the surface is pre-treated by application of a bonding layer comprising zinc or tin. The application of the bonding layer may be by a zincate or a stannate treatment. The use of lead to promote wetting during brazing can be reduced or avoided, or other elements such as bismuth can be used.

Claims

1. A method of manufacturing a brazing sheet product, comprising the steps of:

plating a layer comprising nickel onto a surface of a sheet comprising a core sheet and a clad layer on the core sheet, the clad layer being made of an aluminium alloy containing silicon in an amount in the range 2 to 18% by weight and said surface being a surface of the clad layer, and

pretreating said surface before the plating step,

wherein the pretreating comprises applying a bonding layer comprising zinc or tin on said surface.

2. The method according to claim 1, wherein said bonding layer is applied by a zincate treatment or a stannate treatment.

3. The method according to claim 2, wherein said bonding layer is applied by an immersion zincate treatment or an immersion stannate treatment.

4. The method according to claim 2, wherein the duration of the zincate or stannate treatment is in the range 1 to 300 seconds.

5. The method according to claim 2, wherein the temperature of the zincate or stannate treatment is in the range of 10 to 50°

C.

6. The method according to claim 1, wherein said bonding layer has a thickness of not more than 1 μ

m.

7. The method according to claim 6, wherein said bonding layer has a thickness in the range 10 to 150 nm.

8. The method according to claim 1, wherein said layer comprising nickel is applied by electroplating.

9. The method according to claim 8, wherein said electroplating is carried out in a sulfamate solution.

10. The method according to claim 9, wherein said sulfamate solution contains lead, whereby said nickel layer contains lead.

11. The method according to claim 8, wherein said layer comprising nickel is applied by electroplating in which one or more process parameters are selected from:

(a) electroplating bath temperature 20-70°

C.;

(b) electroplating bath pH 7.0-12.0;

(c) current density of 0.1-10.0 A/dm²;

(d) plating time 1 to 300 seconds;

(e) bath composition comprising 3-200 g/l nickel sulfate, 10-100 g/l nickel chloride, 60-300 g/l sodium citrate, 0.05-10.0 g/l lead acetate, and 5-150 ml/l ammonium hydroxide (calculated as 30% ammonium hydroxide solution).

12. The method according to claim 8, wherein said layer comprising nickel is applied by electroplating in which one or more process parameters are selected from:

(a) electroplating bath temperature 20-70°

C.;

(b) electroplating bath pH in the range of 3 to 5;

(c) current density of 0.1-10.0 A/dm²;

(d) plating time 1 to 300 seconds;

(e) bath composition comprising 5-400 g/l nickel sulfate, 10-100 g/l nickel chloride, 5-100 g/l boric acid.

13. The method according to claim 1, wherein the amount of silicon in said clad layer is in the range 7 to 18% by weight.

15. The brazing sheet product according to claim 14, wherein said clad layer (2) has discrete silicon-rich particles exposed at said outer surface thereof, and said layer (3) comprising nickel is bonded both to said silicon-rich particles and to the areas of said outer surface between said silicon-rich particles, so as to form a continuous layer on said outer surface.

16. The brazing sheet product according to claim 14, wherein said bonding layer (4) is an electroplated layer.

17. The brazing sheet product according to claim 14, wherein said bonding layer (4) has a thickness of not more than 0.5 μ

m.

18. The brazing sheet product according to claim 14, wherein said bonding layer (4) has a thickness in the range 20 to 150 nm.

19. The brazing sheet product according to claim 14, wherein said layer (3) comprising nickel has a thickness of not more than 2.0 μ

m.

20. The brazing sheet product according to claim 14, wherein taken together said clad layer and all layers exterior thereto, have a composition containing at least one of the following elements,

Bi in the range of 0.01 to 0.5% by weight,

Mg in the range 0.2 to 2.0% by weight, and

Sb in the range of 0.01 to 0.5% by weight.

21. The brazing sheet product according to claim 14, wherein said bonding layer (4) contains by weight an amount not more than 50%, in total of one or more elements selected from bismuth, lead, lithium and antimony.

22. The brazing sheet product according to claim 14, wherein said clad layer (2) contains by weight Mg in an amount of at most 8%.

23. The brazing sheet product according to claim 14, wherein said clad layer (2) contains by weight Zn in an amount of at most 5%.

24. The brazing sheet product according to claim 14, wherein said core sheet (1) is an aluminium alloy.

25. The brazing sheet product according to claim 24, wherein said core sheet (1) is an aluminium alloy comprising Mg in an amount of at most 8%.

26. The brazing sheet product according to claim 14, wherein said core sheet (1) is coupled to said clad layer (2) via an intermediate layer (5).

27. An assembly of components joined by brazing, at least one said components being a brazing sheet product according to claim 14.

29. The method of claim 6, wherein said bonding layer has a thickness of not more than 0.3 μ

m.

30. The method according to claim 8, wherein said layer comprising nickel is applied by electroplating in which one or more process parameters are selected from:

(a) electroplating bath temperature 20-30°

C.;

(b) electroplating bath pH 10.0-12.0;

(c) current density of 0.5-4.0 A/dm²;

(d) plating time 30 to 100 seconds;

(e) bath composition comprising 3-200 g/l nickel sulfate, 10-100 g/l nickel chloride, 60-100 g/l sodium citrate, 0.05-10.0 g/l lead acetate, and 5-150 ml/l ammonium hydroxide (calculated as 30% ammonium hydroxide solution).

31. The method of claim 11, wherein the electroplating bath pH is about 10.5 and the bath composition comprises about 100 g/l sodium citrate.

32. The method according to claim 8, wherein said layer comprising nickel is applied by electroplating in which one or more process parameters are selected from:

(a) electroplating bath temperature 40 to 60°

C.;

(b) electroplating bath pH in the range of 4 to 5;

(c) current density of 0.5 to 5.0 A/dm²;

(d) plating time 20 to 100 seconds;

(e) bath composition comprising 240-300 g/l nickel sulphate, 40-60 g/l nickel chloride, 25-40 g/l boric acid.

33. The brazing sheet product according to claim 14, wherein said bonding layer (4) has a thickness of not more than 0.3 μ

m.

34. The brazing sheet product according to claim 14, wherein said layer (3) comprising nickel has a thickness of not more than 1.0 μ

m.

35. The brazing sheet product according to claim 14, wherein taken together said clad layer and all layers exterior thereto, have a composition containing at least one of the following elements,

Bi in the range of 0.05 to 0.5% by weight,

Mg in the range 0.2 to 2.0% by weight, and

Sb in the range of 0.05 to 0.5% by weight.

36. The brazing sheet product according to claim 14, wherein said bonding layer (4) contains by weight an amount of not more than 25%, in total of one or more elements selected from bismuth, lead, lithium and antimony.

37. The brazing sheet product according to claim 14, wherein said clad layer (2) contains by weight Mg in an amount in the range of 0.5 to 5%.

38. The brazing sheet product according to claim 14, wherein said clad layer (2) contains by weight Zn in an amount in the range of 0.5 to 3%.

14. A brazing sheet product comprising a core sheet (1), a clad layer (2) on said core sheet (1) made of an aluminium alloy containing silicon in an amount in the range 2 to 18% by weight, a layer (3) comprising nickel on the outer surface of said clad layer, and a layer (4) comprising zinc or tin as a bonding layer between said outer surface of said clad layer and said layer comprising nickel.

28. A method of manufacturing an assembly of brazed components, comprising the steps of:

(a) forming said components of which at least one is made from brazing sheet product according to claim 14;

(b) assembling the components into the assembly;

(c) brazing the assembly under a vacuum or in an inert atmosphere in the absence of a brazing-flux at elevated temperature for a period long enough for melting and spreading of the clad layer;

(d) cooling the brazed assembly.