Brazing sheet product and method of its manufacture
Disclosed is a brazing sheet product comprising a core metal sheet, on at least one side of the core sheet a clad layer of an aluminium brazing alloy comprising silicon in an amount in the range of 4 to 14% by weight, and further comprising on at least one outersurface of the clad layer a coated layer of iron-X alloy, wherein X is selected from one or more members of the group consisting of tin, zinc, manganese, and copper, and such that the clad layer and all layers exterior thereto form a metal filler for a brazing operation and having a composition with the proviso that the mol-ratio of Fe:X is in the range of 10:(0.3 to 6). The invention also relates to a method of manufacturing such a brazing product, and to a brazed assembly comprising at least one component made of this brazing product.
1. A brazing sheet product comprising a core metal sheet, on at least one side of said core sheet a clad layer of an aluminium brazing alloy comprising silicon in an amount in the range of 4 to 14% by weight, and further comprising on at least one outer surface of said clad layer a coated layer of iron-X alloy, wherein X is selected from one or more members of the group consisting of tin, zinc, manganese, and copper, and such that the clad layer and all layers exterior thereto form a metal filler for a brazing operation and having a composition with the proviso that the mol-ratio of Fe:X is in the range of 10:(0.3 to 6).
2. The brazing sheet product according to claim 1 , wherein the mol-ratio of Fe:X is in the range of 10:(0.5 to >5).
3. The brazing sheet product according to claim 1 , wherein the layer comprising iron-X alloy is formed by a plating method.
4. The brazing sheet product according to claim 1 , wherein the layer comprising iron-X alloy is formed by an electrolytic plating method.
5. The brazing sheet product according to claim 1 , wherein the layer comprising iron-X alloy is formed by a PVD method.
6. The brazing sheet product according to claim 1 , wherein the layer comprising iron-X alloy is formed by a thermal spraying method.
7. The brazing sheet product according to claim 1 , wherein the layer comprising iron-X alloy has a thickness of at most 1.8 μm.
8. The brazing sheet product according to claim 1 , wherein the layer comprising iron-X alloy has a thickness of at most 1.0 μm.
9. The brazing sheet product according to claim 1 , wherein the layer comprising iron-X alloy has a thickness of about 0.03 to 1.8 μm.
10. The brazing sheet product according to claim 1 , wherein the layer comprising iron-X alloy has a thickness of about 0.10 to 1.0 μm.
11. The brazing sheet product according to claim 1 , wherein there is a layer comprising iron or iron alloy between the outer surface of said clad layer and the layer of iron-X alloy.
12. The brazing sheet product according to claim 1 , wherein there is a layer comprising iron or iron alloy, between the outer surface of said clad layer and the layer of iron-X alloy, formed by an electrolytic plating method.
13. The brazing sheet product according to claim 11 , wherein the layer comprising iron or iron alloy comprises at least 80 weight percent iron.
14. The brazing sheet product according to claim 11 , wherein the layer comprising iron or iron alloy comprises at least 85 weight percent iron.
15. The brazing sheet product according to claim 11 , wherein the layer comprising iron or iron alloy comprises at least 90 weight percent iron.
16. The brazing sheet product according to claim 11 , wherein the layer comprising iron or iron alloy comprises at least 96 weight percent iron.
17. The brazing sheet product according to claim 11 , wherein the layer comprising iron or iron alloy comprises at least 98 weight percent iron.
18. The brazing sheet product according to claim 11 , wherein the layer comprising iron or iron alloy has a thickness of at most 2.0 μm.
19. The brazing sheet product according to claim 11 , wherein the layer comprising iron or iron alloy has a thickness of at most 1.0 μm.
20. The brazing sheet product according to claim 11 , wherein the layer comprising iron or iron alloy has a thickness in the range of about 0.1 to 2.0 μm.
21. The brazing sheet product according to claim 11 , wherein the layer comprising iron or iron alloy has a thickness in the range of 0.05 to 0.5 μm.
22. The brazing sheet product according to claim 1 , wherein there is a bonding layer between said outer surface of said clad layer and said layer comprising iron or iron alloy.
23. The brazing sheet product according to claim 1 , wherein there is a bonding layer comprising zinc or tin between said outer surface of said clad layer and said layer comprising iron or iron alloy.
24. The brazing sheet product according to claim 22 , wherein said bonding layer has a thickness in the range of at most 1.0 μm.
25. The brazing sheet product according to claim 22 , wherein said bonding layer has a thickness of at most 0.5 micron.
26. The brazing sheet product according to claim 22 , wherein said bonding layer has a thickness of at most 0.3 μm.
27. The brazing sheet product according to claim 22 , wherein said bonding layer has a thickness in the range of 0.01 to 0.15 μm.
28. The brazing sheet product according to claim 22 , wherein said iron-X layer is substantially lead free.
29. The brazing sheet product according to claim 11 , wherein the layer comprising iron or iron alloy is substantially lead free.
30. The brazing sheet product according to claim 1 , wherein the core metal sheet comprises an member selected from the group consisting of steel, aluminised steel, stainless steel, plated or coated stainless steel, bronze, brass, nickel, nickel alloy, titanium, or plated or coated titanium.
31. The brazing sheet product according to claim 1 , wherein the core metal sheet comprises an aluminium alloy.
32. The brazing sheet product according to claim 1 , wherein the core metal sheet comprises an aluminium alloy selected from the group consisting of AA3xxx, AA5xxx, and AA6xxx-series aluminium alloy.
33. The brazing sheet product according to claim 1 , wherein taken together the clad layer comprising silicon in an amount in the range of 4 to 14% by weight and all layers exterior thereto form a filler metal for a brazing operation and having a composition comprising at least, by weight percent:
Si in the range of 5 to 14%,
Fe in the range of 0.15 to 8%,
X in the range of 0.01 to 7%, and wherein X is selected from one or more members of the group consisting of Sn, Zn, Mn, and Cu.
Sn in the range of 0.0 to 0.3% if not present as X,
Zn in the range of 0.0 to 0.3% if not present as X,
Mn in the range of 0.0 to 0.3% if not present as X,
Cu in the range of 0.0 to 0.3% if not present as X,
optionally one or more of Bi, Sb, In and Pb, wherein:
Bi in the range of 0.0 to 0.3%,
Sb in the range of 0.0 to 0.3%,
In in the range of 0.0 to 0.3%,
Pb in the range of 0.0 to 0.3%,
Ti in the range of 0.0 to 0.1%,
Sr in the range of 0.0 to 0.1%,
Mg in the range of 0.0 to 5%,
balance aluminium and inevitable impurities,
and with the proviso that the mol-ratio of Fe:X is in the range of 10:(0.3 to 6).
34. A method of manufacturing a brazing sheet product according to claim 1 , comprising the steps of: (a) providing a brazing sheet product having a core metal sheet, on at least one side of said core sheet a clad layer of an aluminium brazing alloy comprising silicon in an amount in the range of 4 to 14% by weight, (b) pretreating of the outer surface of the clad alloy, and (c) coating a metal layer onto the outer surface of the pretreated outer surface of the clad alloy, said metal layer comprising an iron-X alloy, wherein X is selected from one or more members of the group consisting of tin, zinc, manganese, and copper.
35. The method according to claim 34 , wherein during step (b) the outer surface of the clad layer is pre-treated by applying a bonding layer.
36. The method according to claim 34 , wherein during step (b) the outer surface of the clad layer is pre-treated by applying a bonding layer comprising zinc or tin.
37. The method according to claim 35 , wherein after applying said bonding layer and before applying the metal layer comprising an iron-X alloy, there is applied a layer comprising more than 85% by weight of iron.
38. The method according to claim 34 , wherein the metal layer is coated onto the outer surface of the pretreated outer surface of the clad alloy by plating.
39. The method according to claim 34 , wherein the metal layer is coated onto the outer surface of the pretreated outer surface of the clad alloy by PVD.
40. The method according to claim 34 , wherein the metal layer is coated onto the outer surface of the pretreated outer surface of the clad alloy by thermal spraying.
41. The method according to claim 34 , wherein the iron X layer is substantially lead-free.
42. The method according to claim 34 , wherein the layer comprising iron or iron alloy is substantially lead-free.
43. The method according to claim 34 , wherein the layer comprising iron or iron alloy comprises at least 80 weight percent iron.
44. The method according to claim 34 , wherein the layer comprising iron or iron alloy comprises at least 85 weight percent iron.
45. The method according to claim 34 , wherein the layer comprising iron or iron alloy comprises at least 90 weight percent iron.
46. The method according to claim 34 , wherein the layer comprising iron or iron alloy comprises at least 96 weight percent iron.
47. The method according to claim 34 , wherein the layer comprising iron or iron alloy comprises at least 98 weight percent iron.
48. An assembly of components joined by brazing, at least one said components being a brazing sheet product according to claim 1 .
49. The assembly according to claim 48 , wherein said at least one component is joined by brazing to at least one other component made of a material selected from the group consisting of steel, aluminised steel, stainless steel, plated or coated stainless steel, bronze, brass, nickel, nickel alloy, titanium, and plated or coated titanium.
50. The assembly according to claim 48 , wherein the assembly is a heat exchanger.
51. The assembly according to claim 48 , wherein the assembly is a fuel cell.
52. The assembly according to claim 48 , wherein the assembly is an electrochemical fuel cell.
53. The assembly according to claim 48 , wherein the assembly is brazed under a vacuum or in an inert atmosphere in the absence of a brazing-flux material.
54. An assembly of components joined by brazing, at least one said components being a brazing sheet product obtained by the method according to claim 34 .
55. The assembly according to claim 54 , wherein the assembly is brazed under a vacuum or in an inert atmosphere in the absence of a brazing-flux material.
56. The method according to claim 35 , wherein after applying said bonding layer and before applying the metal layer comprising an iron-X alloy, there is applied by plating a layer comprising more than 85% by weight of iron.