CA2165338C - A method of brazing - Google Patents
A method of brazing Download PDFInfo
- Publication number
- CA2165338C CA2165338C CA002165338A CA2165338A CA2165338C CA 2165338 C CA2165338 C CA 2165338C CA 002165338 A CA002165338 A CA 002165338A CA 2165338 A CA2165338 A CA 2165338A CA 2165338 C CA2165338 C CA 2165338C
- Authority
- CA
- Canada
- Prior art keywords
- aluminum
- particles
- coating
- flux
- braze
- Prior art date
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- Expired - Fee Related
Links
- 238000000034 method Methods 0.000 title claims abstract description 110
- 238000005219 brazing Methods 0.000 title claims abstract description 42
- 239000000463 material Substances 0.000 claims abstract description 163
- 239000002245 particle Substances 0.000 claims abstract description 104
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 100
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 100
- 239000011248 coating agent Substances 0.000 claims abstract description 80
- 238000000576 coating method Methods 0.000 claims abstract description 80
- 239000000758 substrate Substances 0.000 claims abstract description 64
- NROKBHXJSPEDAR-UHFFFAOYSA-M potassium fluoride Chemical compound [F-].[K+] NROKBHXJSPEDAR-UHFFFAOYSA-M 0.000 claims abstract description 54
- 239000000945 filler Substances 0.000 claims abstract description 28
- 229910000838 Al alloy Inorganic materials 0.000 claims abstract description 27
- 239000011698 potassium fluoride Substances 0.000 claims abstract description 27
- 235000003270 potassium fluoride Nutrition 0.000 claims abstract description 27
- IRPGOXJVTQTAAN-UHFFFAOYSA-N 2,2,3,3,3-pentafluoropropanal Chemical compound FC(F)(F)C(F)(F)C=O IRPGOXJVTQTAAN-UHFFFAOYSA-N 0.000 claims abstract description 26
- KLZUFWVZNOTSEM-UHFFFAOYSA-K Aluminum fluoride Inorganic materials F[Al](F)F KLZUFWVZNOTSEM-UHFFFAOYSA-K 0.000 claims abstract description 26
- 238000010438 heat treatment Methods 0.000 claims abstract description 12
- 230000000717 retained effect Effects 0.000 claims abstract description 9
- 150000001875 compounds Chemical class 0.000 claims abstract description 8
- 239000011347 resin Substances 0.000 claims description 47
- 229920005989 resin Polymers 0.000 claims description 47
- 230000008018 melting Effects 0.000 claims description 25
- 238000002844 melting Methods 0.000 claims description 25
- 229910052751 metal Inorganic materials 0.000 claims description 23
- 239000002184 metal Substances 0.000 claims description 23
- 229910052710 silicon Inorganic materials 0.000 claims description 17
- 239000000956 alloy Substances 0.000 claims description 16
- 239000010703 silicon Substances 0.000 claims description 16
- 230000001464 adherent effect Effects 0.000 claims description 15
- 229910045601 alloy Inorganic materials 0.000 claims description 15
- 238000004519 manufacturing process Methods 0.000 claims description 15
- 239000000203 mixture Substances 0.000 claims description 13
- -1 aluminum-copper-magnesium Chemical compound 0.000 claims description 9
- 230000005496 eutectics Effects 0.000 claims description 7
- 239000004925 Acrylic resin Substances 0.000 claims description 6
- 229920000178 Acrylic resin Polymers 0.000 claims description 6
- 238000005304 joining Methods 0.000 claims description 6
- 239000000155 melt Substances 0.000 claims description 6
- 239000002904 solvent Substances 0.000 claims description 5
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 4
- 229920003229 poly(methyl methacrylate) Polymers 0.000 claims description 4
- 239000004926 polymethyl methacrylate Substances 0.000 claims description 4
- WPPDFTBPZNZZRP-UHFFFAOYSA-N aluminum copper Chemical compound [Al].[Cu] WPPDFTBPZNZZRP-UHFFFAOYSA-N 0.000 claims description 3
- FJMNNXLGOUYVHO-UHFFFAOYSA-N aluminum zinc Chemical compound [Al].[Zn] FJMNNXLGOUYVHO-UHFFFAOYSA-N 0.000 claims description 3
- 229910001610 cryolite Inorganic materials 0.000 claims description 3
- 239000011876 fused mixture Substances 0.000 claims description 3
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 3
- 150000002910 rare earth metals Chemical class 0.000 claims description 3
- 230000004907 flux Effects 0.000 abstract description 16
- 238000001816 cooling Methods 0.000 abstract description 5
- 238000000889 atomisation Methods 0.000 abstract description 2
- 241000282337 Nasua nasua Species 0.000 abstract 1
- 239000010410 layer Substances 0.000 description 18
- 230000008569 process Effects 0.000 description 14
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 13
- 238000005253 cladding Methods 0.000 description 9
- 239000007788 liquid Substances 0.000 description 8
- 239000000843 powder Substances 0.000 description 8
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 7
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 239000011162 core material Substances 0.000 description 5
- 239000002923 metal particle Substances 0.000 description 5
- 229910000676 Si alloy Inorganic materials 0.000 description 4
- 238000005275 alloying Methods 0.000 description 4
- 239000000470 constituent Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 3
- 230000002411 adverse Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 239000000356 contaminant Substances 0.000 description 3
- 238000005238 degreasing Methods 0.000 description 3
- 238000005530 etching Methods 0.000 description 3
- 238000001125 extrusion Methods 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- XSTXAVWGXDQKEL-UHFFFAOYSA-N Trichloroethylene Chemical group ClC=C(Cl)Cl XSTXAVWGXDQKEL-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 239000006069 physical mixture Substances 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- UBOXGVDOUJQMTN-UHFFFAOYSA-N trichloroethylene Natural products ClCC(Cl)Cl UBOXGVDOUJQMTN-UHFFFAOYSA-N 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- CRTPOZARBMQHRY-UHFFFAOYSA-L [F-].[Al+3].[F-].[K+] Chemical compound [F-].[Al+3].[F-].[K+] CRTPOZARBMQHRY-UHFFFAOYSA-L 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000001680 brushing effect Effects 0.000 description 1
- 150000008280 chlorinated hydrocarbons Chemical class 0.000 description 1
- 238000007739 conversion coating Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- 238000010587 phase diagram Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- SKFYTVYMYJCRET-UHFFFAOYSA-J potassium;tetrafluoroalumanuide Chemical compound [F-].[F-].[F-].[F-].[Al+3].[K+] SKFYTVYMYJCRET-UHFFFAOYSA-J 0.000 description 1
- 229940098458 powder spray Drugs 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 239000011833 salt mixture Substances 0.000 description 1
- 239000011856 silicon-based particle Substances 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000004901 spalling Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C24/00—Coating starting from inorganic powder
- C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
- C23C24/10—Coating starting from inorganic powder by application of heat or pressure and heat with intermediate formation of a liquid phase in the layer
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
- B23K35/0222—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape for use in soldering, brazing
- B23K35/0244—Powders, particles or spheres; Preforms made therefrom
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
- B23K35/3601—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest with inorganic compounds as principal constituents
- B23K35/3603—Halide salts
- B23K35/3605—Fluorides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/28—Selection of soldering or welding materials proper with the principal constituent melting at less than 950 degrees C
- B23K35/286—Al as the principal constituent
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
- B23K35/3612—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest with organic compounds as principal constituents
- B23K35/3613—Polymers, e.g. resins
Abstract
A method of brazing is provided herein. The method includes the first step of applying a layer of particles of an aluminum alloy filler material. The particles have a coating of a first inorganic flux--type material, e.g., a compound of potassium fluoride and aluminum fluoride together with, or also with, other inorganic flux-type materials, (which has been produced by a particularly-recited and specified method) to at least one of the articles, such that the particles are retained at, or adjacent to, at least a part of the joint between the articles. The next step involves heating to cause the flux - type material and the aluminum alloy filler material to melt and form a brazed joint. The flux coating on the particles of aluminum alloy filler is formed during the atomization procedure. The final step includes cooling the substrate to solidify the aluminum coati ng material.
Description
'' (a) TITLE OF THE INVENTION
A METHOD OF BRAZING
(b) TECHNICAL FIELD TO WHICH THE INVENTION RELATES
The present invention relates to a method for the joining together by brazing of two or more metal articles.
(c) BACKGROUND ART
Brazing processes for the joining together of two or more articles made of metal, e.g., aluminum-based materials are well known. However, in the case of aluminum materials, all the known methods have disadvantages relating to difficulty of process control, and hence reliability of the brazed joint, limitations on materials which may be employed, disadvantages of cost or any combination of these.
One known process, widely employed for the production of aluminum heat exchangers, e.g., radiators for vehicles, requires that the aluminum material of which the radiator is composed first be clad with a brazing alloy of a second aluminum alloy having a lower melting point than the substrate aluminum material. The requirement for cladding, usually carried out by a cold-pressure welding technique, e.g., roll-bonding, is very expensive, and brings with it further disadvantages.
Because of the number of different sized tubes and components used in a radiator assembly, it is only economically feasible to carry out the cladding process on sheet or flat strip material from which the various radiator components are then fabricated. In the case of tubular components, this necessitates a seam-weld which causes the substrate aluminum material and the cladding alloy to fuse together, thus lowering the melting point of the resulting alloy in the welded region, relative to the substrate material, through the complete wall thickness of the tube component in the heat affected zone (HAZ). This results in the generation of high levels of scrap due to the penetration of the braze into the welded tube in the HAZ, thereby causing cracks and/or pinhole porosity.
The clad brazing alloy is usually an aluminum-silicon alloy of approximately eutectic composition. Silicon from the cladding alloy tends to diffuse into the substrate material over the entire clad area, thus lowering the melting temperature even before the clad brazing alloy has melted.
This exacerbates the problem of penetration and porosity.
Because of the method of forming the radiator tube sections, they are relatively weak, and even those tubes which do not have readily apparent leaks may be relatively weak and fail prematurely in service due to fatigue from flexing due to the fluctuating water pressure in the radiator. In practice, the use of a higher strength aluminum alloy having better fatigue resistance is precluded in the known brazing processes because the fluxes which are employed are known to react with the alloying constituents negating the fluxing effect and also A
A METHOD OF BRAZING
(b) TECHNICAL FIELD TO WHICH THE INVENTION RELATES
The present invention relates to a method for the joining together by brazing of two or more metal articles.
(c) BACKGROUND ART
Brazing processes for the joining together of two or more articles made of metal, e.g., aluminum-based materials are well known. However, in the case of aluminum materials, all the known methods have disadvantages relating to difficulty of process control, and hence reliability of the brazed joint, limitations on materials which may be employed, disadvantages of cost or any combination of these.
One known process, widely employed for the production of aluminum heat exchangers, e.g., radiators for vehicles, requires that the aluminum material of which the radiator is composed first be clad with a brazing alloy of a second aluminum alloy having a lower melting point than the substrate aluminum material. The requirement for cladding, usually carried out by a cold-pressure welding technique, e.g., roll-bonding, is very expensive, and brings with it further disadvantages.
Because of the number of different sized tubes and components used in a radiator assembly, it is only economically feasible to carry out the cladding process on sheet or flat strip material from which the various radiator components are then fabricated. In the case of tubular components, this necessitates a seam-weld which causes the substrate aluminum material and the cladding alloy to fuse together, thus lowering the melting point of the resulting alloy in the welded region, relative to the substrate material, through the complete wall thickness of the tube component in the heat affected zone (HAZ). This results in the generation of high levels of scrap due to the penetration of the braze into the welded tube in the HAZ, thereby causing cracks and/or pinhole porosity.
The clad brazing alloy is usually an aluminum-silicon alloy of approximately eutectic composition. Silicon from the cladding alloy tends to diffuse into the substrate material over the entire clad area, thus lowering the melting temperature even before the clad brazing alloy has melted.
This exacerbates the problem of penetration and porosity.
Because of the method of forming the radiator tube sections, they are relatively weak, and even those tubes which do not have readily apparent leaks may be relatively weak and fail prematurely in service due to fatigue from flexing due to the fluctuating water pressure in the radiator. In practice, the use of a higher strength aluminum alloy having better fatigue resistance is precluded in the known brazing processes because the fluxes which are employed are known to react with the alloying constituents negating the fluxing effect and also A
adversely affecting the melting behaviour of the aluminum alloy.
U.S. Patent No. 3,951,328 describes a process for brazing aluminum heat exchangers as described above. This document describes the use of a flux of potassium fluoaluminate which is formed by fusing together potassium fluoride and aluminum fluoride such that no free potassium fluoride remains. The fused mixture is then ground into a powder and used as a flux. The document also mentions that the flux powder may be combined with aluminum alloy braze powder to form a physical mixture of the different types of powder particle and used to braze unclad aluminum material components. However, the quality of joint which is produced by this latter method is relatively poor and has a high reject rate. Thus, industrial processes currently in use employ the clad brazing alloy route.
EP-A-0140267 describes a method of brazing an aluminum material by forming thereon a flux layer of potassium pentafluoaluminate by electrochemical deposition from an aqueous solution to produce a chemical conversion coating either on the material to be joined together or on braze particles.
..~.
U.S. Patent No. 3,951,328 describes a process for brazing aluminum heat exchangers as described above. This document describes the use of a flux of potassium fluoaluminate which is formed by fusing together potassium fluoride and aluminum fluoride such that no free potassium fluoride remains. The fused mixture is then ground into a powder and used as a flux. The document also mentions that the flux powder may be combined with aluminum alloy braze powder to form a physical mixture of the different types of powder particle and used to braze unclad aluminum material components. However, the quality of joint which is produced by this latter method is relatively poor and has a high reject rate. Thus, industrial processes currently in use employ the clad brazing alloy route.
EP-A-0140267 describes a method of brazing an aluminum material by forming thereon a flux layer of potassium pentafluoaluminate by electrochemical deposition from an aqueous solution to produce a chemical conversion coating either on the material to be joined together or on braze particles.
..~.
(d) DESCRIPTION OF THE INVENTION
It is an object of one aspect of the present invention to provide a reliable brazing process which does not require the aluminum substrate material to be clad.
It is an object of a further aspect of the present invention to provide a brazing process which allows the use of extruded tube sections having higher strength and/or made from aluminum alloy having a higher strength, thus being inherently more fatigue resistant.
It is an object of a yet further aspect of the present invention to provide a brazing process whereby the brazing filler material and any flux-type material may be accurately located on the components to be joined to reduce the amount of these materials which are used to effect the brazed joint and thus reduce wastage.
It is an object of still another aspect of the present invention to provide a process for rendering a substrate which is susceptible to wetting by a molten aluminum filler material and thus forming an adherent aluminum material coating on the substrate, and in which the aluminum material may be substantially pure aluminum or may be an aluminum alloy .
According to a first aspect of the present invention, a method of is provided for forming an adherent aluminum material coating on a substrate having a higher melting point than the aluminum braze coating material, the aluminum braze coating material being formed of aluminum braze particles which are coated with an inorganic flux-type material, i.e., a compound of potassium fluoride and aluminum fluoride together with, or also with, other inorganic flux-type materials, the method including the steps of g producing the aluminum braze particles by the steps of atomizing molten aluminum material, and coating the atomized aluminum braze material with inorganic molten the flux-type material during the production procedure, and raising the temperature of the substrate and the coated braze particles so as to cause the coated braze particles to melt 5 and to form an adherent coating on the substrate.
By another aspect, the present invention provides a method of forming an adherent aluminum material coating on a substrate having a higher melting point than the aluminum braze coating material, the aluminum braze coating material being formed of aluminum braze particles which are coated with an inorganic flux-type material, i.e., potassium fluoride and aluminum fluoride together with, or also with, other inorganic flux-type materials, the method including the steps of producing the aluminum braze particles by the steps of atomizing molten aluminum material, and coating the atomized aluminum braze material with inorganic molten flux-type material during the production procedure, causing the coated aluminum braze particles to be retained on the substrate by being associated with a resin which is applied to the surface, and raising the temperature of the substrate and the coated braze particles so as to cause the coated braze particles to melt and to form an adherent coating on the substrate.
By one variant of such methods, the coating is an aluminized coating on a ferrous substrate.
By another variant of such methods and the above variant thereof, the coating is used as an intermediate brazing layer to join an article to the substrate.
It is an object of one aspect of the present invention to provide a reliable brazing process which does not require the aluminum substrate material to be clad.
It is an object of a further aspect of the present invention to provide a brazing process which allows the use of extruded tube sections having higher strength and/or made from aluminum alloy having a higher strength, thus being inherently more fatigue resistant.
It is an object of a yet further aspect of the present invention to provide a brazing process whereby the brazing filler material and any flux-type material may be accurately located on the components to be joined to reduce the amount of these materials which are used to effect the brazed joint and thus reduce wastage.
It is an object of still another aspect of the present invention to provide a process for rendering a substrate which is susceptible to wetting by a molten aluminum filler material and thus forming an adherent aluminum material coating on the substrate, and in which the aluminum material may be substantially pure aluminum or may be an aluminum alloy .
According to a first aspect of the present invention, a method of is provided for forming an adherent aluminum material coating on a substrate having a higher melting point than the aluminum braze coating material, the aluminum braze coating material being formed of aluminum braze particles which are coated with an inorganic flux-type material, i.e., a compound of potassium fluoride and aluminum fluoride together with, or also with, other inorganic flux-type materials, the method including the steps of g producing the aluminum braze particles by the steps of atomizing molten aluminum material, and coating the atomized aluminum braze material with inorganic molten the flux-type material during the production procedure, and raising the temperature of the substrate and the coated braze particles so as to cause the coated braze particles to melt 5 and to form an adherent coating on the substrate.
By another aspect, the present invention provides a method of forming an adherent aluminum material coating on a substrate having a higher melting point than the aluminum braze coating material, the aluminum braze coating material being formed of aluminum braze particles which are coated with an inorganic flux-type material, i.e., potassium fluoride and aluminum fluoride together with, or also with, other inorganic flux-type materials, the method including the steps of producing the aluminum braze particles by the steps of atomizing molten aluminum material, and coating the atomized aluminum braze material with inorganic molten flux-type material during the production procedure, causing the coated aluminum braze particles to be retained on the substrate by being associated with a resin which is applied to the surface, and raising the temperature of the substrate and the coated braze particles so as to cause the coated braze particles to melt and to form an adherent coating on the substrate.
By one variant of such methods, the coating is an aluminized coating on a ferrous substrate.
By another variant of such methods and the above variant thereof, the coating is used as an intermediate brazing layer to join an article to the substrate.
The method according to an embodiment of aspects of the present invention may be used to produce an adherent aluminized coating on a ferrous, e.g., steel, substrate.
The coating may be used purely as a protective, corrosion-resistant coating, or may be used as an intermediate interface layer between the ferrous substrate and an article of an aluminum material which is simultaneously or subsequently bonded thereto by the brazing method.
In another embodiment of these methods of aspects of the present invention, a layer of a liquid resin or plastics material (hereinafter referred to simply as "resin") is first applied to the substrate to be coated. The liquid resin material may comprise any suitable resin which may be dissolved, for example, in a solvent and subsequently may be solidified by driving off the solvent by, for example, heating. The use of a liquid resin allows the filler material and flux-type material to be accurately placed on the substrate in the specific areas where it is required, thus reducing waste. The liquid resin may be applied by printing, spraying, brushing or painting on the substrate, or by any other suitable method of application known in the art.
Desirably, the resin material should leave no residue after heating for its removal.
On heating, the resin should be entirely removed before the aluminum material and flux-type material have started to melt.
Acrylic resins, e.g., polymethylmethacrylate and its variants, have been found to be suitable. Suitable solvents include chlorinated hydrocarbons, e.g., trichloroethylene, hydrocarbons, e.g., toluene, and ketones, e.g., methyl ethyl ketone.
The coating may be used purely as a protective, corrosion-resistant coating, or may be used as an intermediate interface layer between the ferrous substrate and an article of an aluminum material which is simultaneously or subsequently bonded thereto by the brazing method.
In another embodiment of these methods of aspects of the present invention, a layer of a liquid resin or plastics material (hereinafter referred to simply as "resin") is first applied to the substrate to be coated. The liquid resin material may comprise any suitable resin which may be dissolved, for example, in a solvent and subsequently may be solidified by driving off the solvent by, for example, heating. The use of a liquid resin allows the filler material and flux-type material to be accurately placed on the substrate in the specific areas where it is required, thus reducing waste. The liquid resin may be applied by printing, spraying, brushing or painting on the substrate, or by any other suitable method of application known in the art.
Desirably, the resin material should leave no residue after heating for its removal.
On heating, the resin should be entirely removed before the aluminum material and flux-type material have started to melt.
Acrylic resins, e.g., polymethylmethacrylate and its variants, have been found to be suitable. Suitable solvents include chlorinated hydrocarbons, e.g., trichloroethylene, hydrocarbons, e.g., toluene, and ketones, e.g., methyl ethyl ketone.
The aluminum filler material and flux-type material may be mixed with liquid resin and then be applied to the substrate simultaneously, or may be "dusted"
onto the liquid resin after the resin layer has been applied. The result of either technique is to cause the aluminum material and flux-type material to adhere to the surface of the substrate only in those areas where it is desired. However, it is preferred to "dust" the coated powder particles onto the resin as the particles are not then entirely coated by the resin and the possibility of the flux-type material being subsequently harmed by the resin during heating is greatly reduced. Alternatively, the coated aluminum-based filler material particles may be applied by any suitable carrier medium including, for example, an aqueous slurry.
According to another aspect of the present invention, a method is provided for joining together two or more articles of aluminum-based material, the method comprising the steps of applying a layer of particles of an aluminum alloy filler material, the particles having a coating of a flux-type material, i.e., a compound of potassium fluoride and aluminum fluoride together with, or also with, other inorganic flux-type materials, to at least one of the articles such that the particles are retained at, or adjacent to, at least a part of the joint between the articles, and heating to cause the flux-type material and the aluminum alloy filler material to melt and to form a brazed joint between the two or more articles.
By a variant of this method of an aspect of this invention, the aluminum braze particles may be produced by the steps of atomizing molten aluminum material, and coating the atomized aluminum braze material with inorganic molten the flux-type a g material during the production procedure, and raising the temperature of the substrate and the coated braze particles so as to cause the coated braze particles to melt and to form an adherent coating on the substrate.
By another variant of this method of an aspect of this invention, the aluminum braze particles may alternatively be produced by the steps of atomizing molten aluminum material, coating the atomized aluminum braze material with inorganic molten the flux-type material during the production procedure, and causing the coated aluminum braze particles to be retained on the substrate by being associated with a resin which is applied to the surface and raising the temperature of the substrate and the coated braze particles so as to cause the coated braze particles to melt and to form an adherent coating on the substrate.
By yet another aspect of this invention, a method is provided of joining together articles of an aluminum material by brazing, the method comprising the steps of applying, to a desired joint region of at least one of the articles, a layer of particles of an aluminum brazing material, the aluminum brazing material comprising particles of an aluminum alloy filler material, the particles being coated with a flux-type material comprising potassium fluoride and aluminum fluoride, the aluminum brazing material particles having been manufactured by the steps of atomizing molten aluminum material, coating the atomized aluminum braze material with inorganic molten flux-type material during the production procedure, causing the coated aluminum braze particles to be retained on the substrate by being associated with a resin which is applied to the surface and raising the temperature of the substrate and the coated braze particles so as to cause B:
°'~ 9 the coated braze particles to melt and to form an adherent coating on the substrate, releasing the coated aluminum brazing material particles on the surface of the at least one article by means of a resin which is applied to the surface of the at least one article, and raising the temperature of the articles and the coated aluminum brazing material particles so as to cause the particles to melt and form a brazed joint between the articles.
By one variant of this method of this aspect of this invention, the filler material includes silicon in the range from 5 to 50 wt % . By a variation thereof, the filler material includes silicon in the range from 7 to 15 wt % .
By another variant of this method of this aspect of this invention, or the above variant thereof, the aluminum alloy filler material is selected from the group of alloys consisting of aluminum-copper, aluminum-copper-magnesium, aluminum-zinc and aluminum plus rare earth metal.
By yet another variant of this method of this aspect of this invention, or the above variants thereof, the flux-type material comprises a fused mixture of aluminum fluoride and potassium fluoride. By a variation thereof, the flux-type material coating comprises from 40 to 50 wt% of potassium fluoride and from 60 to 50 wt% of aluminum fluoride.
By another variation thereof, the flux-type coating is of substantially eutectic composition with respect to potassium fluoride and aluminum fluoride. By still another variation thereof, the mixture of aluminum fluoride and potassium fluoride comprises cryolite.
By still another variant of this method of this aspect of this invention, or the above variants thereof, the flux-type coating also includes silicon.
B, By still a further variant of this method of this aspect of this invention, or the above variants thereof, the proportion of the flux-type coating to metal is from 5 to 30 wt % . By a variation thereof, the proportion is from 10 to 20 wt % .
By still yet another variant of this method of this aspect of this invention, or the 5 above variants thereof, the coated particles are mixed with the resin.
By yet another variant of this method of this aspect of this invention, or the above variants thereof, the coated particles are "dusted" onto the resin. By a variation thereof, the resin is applied dissolved in a solvent to liquefy it. By another variation thereof, the resin is an acrylic resin. By still a further variation thereof, the acrylic resin is 10 polymethylmethacrylate.
By yet a further variant of this method of this aspect of this invention, or the above variants thereof, the resin is removed by heating before the flux-type coating melts.
By a further variant of this method of this aspect of this invention, or the above variants thereof, the flux-type coating melts before the aluminum coating or the filler material.
By a still further variant of this method of this aspect of this invention, or the above variants thereof, the articles are unclad.
According to further aspects of this invention, the articles of aluminum-based material may be unclad.
The aluminum alloy filler material may contain silicon in the range from 5 to wt % . Preferably, where the alloy contains silicon, this may be in the range from 7 to 15 wt % .
Where the filler material is an aluminum-silicon alloy, it may also contain other alloying additions, e.g., copper and/or magnesium.
In one embodiment of the method of one aspect of the present invention, the composition of the aluminum alloy filler material includes silicon in the range from 9 to 12 wt% . Other aluminum alloys, e.g., aluminum-copper, aluminum-copper-magnesium, aluminum-zinc and aluminum plus rare-earth metals, for example, may be used.
Preferably, the compound of potassium fluoride and aluminum fluoride flux-type material comprises from 40 to 50 wt % of potassium fluoride and from 60 to 50 wt % of aluminum fluoride.
The proportion of flux-type material to metal in the braze particles may lie in the range from 5 to 30 wt % . A preferred range may be from 10 to 20 wt % of flux-type material to metal.
The layer of coated particles may be applied as a monolayer of particles.
As with the method of the first aspect of the present invention, in this method of a further aspect of the present invention, the coated particles may be adhered to the surface with a resin medium or with any other suitable carrier medium, the same considerations again applying.
The solidified resin allows more robust handling of any assemblies prior to brazing without the danger that the aluminum alloy filler material and the flux-type material will be shaken off.
The thickness and consistency of the applied resin layer may be controlled to govern the quantity of the coated metal powder particles which may be made to adhere to the substrate .
All the parameters of the resin discussed with reference to the method of the first aspect of the invention are applicable to the method of this second aspect of the invention.
Prior to coating the substrate of the articles to be joined with the liquid resin, at least the surfaces to be joined may first be cleaned by degreasing, followed by a step of, e.g., acid etching, to remove the oxide film which may be present on aluminum materials.
It must be stressed, however, that any method of retaining the braze particles in the required position may be °y employed, including trapping the particles between the surfaces to be joined.
It is a particular advantage of the method of aspects of the present invention that the methods have been found to be significantly more tolerant of surface contaminants, both inorganic and organic, than known brazing processes. In known processes, degreasing and acid etching to remove surface contaminants and the oxide film have been necessary.
Alternatively, ultrasonic degreasing which also disrupts the oxide film has been used. In the method of aspects of the present invention, it has been found that removal or disruption of the oxide film is not necessary.
It has been found that on melting, the fused potassium fluoride/aluminum fluoride flux-type coating on the aluminum silicon alloy particles reacts with the surface of the aluminum substrate to disrupt the oxide film and allows the molten particle contained within the coating to alloy with the metallic surface of the substrate. Tests conducted on articles brazed together by the method of the second aspect of this invention have shown substantial quantities of silicon present in the surface regions of the substrate. Furthermore, the quantity of filler material, as witnessed by the braze fillets present within the body of the joint and at the periphery of brazed joints, significantly exceeds the quantity of metal which was initially applied in the form of aluminum alloy braze particles.
A
The potassium fluoride and aluminum fluoride mixture may comprise the naturally occurring mineral, cryolite.
An advantage of the method of aspects of the present invention is that aluminum braze filler materials having lower melting points than used heretofore may now be used due to the lower melting point of the flux-type material.
A further advantage of the method of aspects of the present invention is that there is no possibility of the metal braze particles and flux-type material segregating since the two constituents are combined together, unlike the physical mixtures of flux and braze particles of the prior art.
The aluminum alloy braze material and the flux-type coating material both melt at a substantially lower temperature than that of the substrate aluminum-based material. Therefore, there is no need for the substrate articles to be clad with a lower melting point material prior to brazing. Tubes for radiators may now be formed by extrusion. Thus there is now no need to form weld seams which have different melting characteristics from the rest of the tube. Since the tubes may now be formed by extrusion, they may also have increased wall thickness and may also be formed with internal strengthening ribs to lessen the possibility of fatigue failure of the tubes.
In addition to the tubes being made by an extrusion technique, aluminum alloys of higher strength may also be used since the flux-type material used in the method of aspects of A
W" 15 the present invention is not adversely affected by alloying elements, e.g., magnesium, and neither is the substrate material adversely affected by the flux-type material.
(e) DESCRIPTION OF THE FIGURES
In the accompanying drawings, Figure 1 shows a schematic cross-section through part of two articles to be joined by a prior art brazing process;
Figure 2 shows part of the aluminum-silicon binary phase equilibrium diagram;
Figure 3 shows a part of the potassium fluoride-aluminum fluoride phase equilibrium diagram;
Figures 4A to 4F show a schematic step-by-step representation of the believed reaction of coated particles with a substrate during a brazing process; and Figure 5 shows a cross-section through an extruded radiator tube.
(f) ONE MODE FOR CARRYING OUT THE INVENTION
Referring now to Figure 1, two articles 10 and 12 are shown which are joined by brazing according to a prior art method. Each article comprises a core 14 of the substrate structural aluminum material, and which is clad on both sides with a layer 16 of a second aluminum alloy material having a substantially lower melting point than that of the core 14.
The surfaces of the two articles are degreased and cleaned by, r :, for example, etching to promote the adherence of a flux material. In the case of a vehicle radiator, the degreased and cleaned component parts, typically comprising airway fins, water tubes, tube plates and side water casings, are assembled together and dipped into a suspension of a flux in deionized water. The dipped assembly is removed from the flux bath and is dried to form a coating 18 of the flux on the clad surfaces . The assembly is then passed into a brazing oven where the temperature is raised to cause first the flux and then the clad surfaces to melt and fuse together to form the brazed joint. One problem which arises with this prior art method is that the flux is highly reactive and will react with contaminants, e.g., water vapour, in the brazing furnace atmosphere, thus negating the desired effect of the flux.
Furthermore, the clad alloy 16 must be metallurgically bonded to the substrate 14 to obviate the formation of an oxide film at the interface between the layers 14 and 16 which would prevent a sound joint being formed between the cladding 16 and the core 14 on melting of the cladding. Because of the need for a metallurgical bond between the core and the cladding, the use of roll-bonding in sheet form is virtually mandatory in order for high enough reductions to be achieved in the working process to secure a metallurgical bond. Thus, tubular items must be fabricated from sheet material by seam-welding causing the problems specified above relating to lowering of A
the melting point through the wall thickness of the tube due to the cladding material alloying with the core material.
Brazing trials were carried out with radiator components made of unclad aluminum alloy having a nominal composition of 0.6 Si/0.7 Fe/ 0.05-0.2 Cu/ 1-1.5 Mn/ balance A1. The components were degreased. After drying, the components were coated with a layer of acrylic resin, in this case polymethyl methacrylate which is dissolved in a toluene/trichloroethylene mixture, in those areas where a brazed joint was required.
Whilst the resin was still in the tacky state particles of metal power of composition 10 wt% Si/balance A1 and having a coating of a flux-type material of composition 40 to 50 wt%
potassium fluoride and 60 to 50 wt% of aluminum fluoride and near to the eutectic composition were dusted onto the surface with a powder spray gun. The coated powder particles had a size lying in the range from 60 to 250 ~,m. The coating thus formed was then dried with a warm air stream to dry the resin and cause the particles to adhere to the resin. The radiator components were then assembled together and passed through a brazing furnace having a nitrogen protective atmosphere. In a preheating zone of the furnace, the resin was driven off by the increasing temperature so that at the onset of melting of the coated particles, no resin remained. In driving off the resin coating, the heating rate should be sufficiently slow so as not to cause spalling of the resin coating. The furnace temperature was set at a nominal temperature which was sufficient to cause melting of the flux-type material and the metal powder particles but not of the substrate aluminum alloy.
Figures 4A to 4F show a schematic representation of what is believed to be the course of forming a brazed joint by the method of aspects of the present invention. Figure 4A shows the surface 40 of a tube 42 and portions of aluminum finning 44 to be brazed thereto for cooling purposes. A layer of resin 46 is applied to the surface 40 and coated particles 48 of aluminum-silicon braze alloy are dusted onto the liquid resin which is then dried. Figures 4B to 4E show the stages of reaction and melting of a coated particle with the surface 40. The surface 40 has an oxide layer 50 thereon, underneath which is the clean aluminum surface 52. On heating, the resin layer 46 dissociates and the products are removed by the flow of a nitrogen gas atmosphere to leave the particles 48 sitting on the surface of the oxide layer 50. As the temperature rises, the flux-type coating 54 melts at 540°C (Figure 4C) whilst the aluminum-silicon particle 56 therein remains solid.
The coating 54 reacts with the oxide layer 50 to disrupt it and allow the metal particle 56 to come into contact with the clean aluminum surface 52. It is believed that at this point substantial diffusion of the silicon from the particle into the substrate occurs. As the temperature rises to 575°C, the metal particle melts and begins to fuse with the surface 52 to alloy therewith and initially form a pit 58 of molten metal.
The silicon from the molten particle continues to diffuse into the molten pit (Figure 4D) and the area of molten surface 52 spreads laterally to j oin with molten areas formed at adj acent particles (Figure 4E). A complete layer of molten metal 60 is then formed (Figure 4F) which is drawn into the gap between the surface 40 and the finning 44 by capillary action. The cooling finning material 44 is similarly affected by the melting of the flux-type coating to allow metal to metal contact between the finning 44 and braze 56. The original flux-type material absorbs the oxide to form a residue with the solidified flux-type material on cooling.
It has been found, surprisingly, that the flux-type coating on the metal particles has a lower melting point than would be expected from the phase diagram shown in Figure 3.
From Figure 3 it may be seen that the melting temperature of the eutectic which is formed by the constituents, potassium fluoride and aluminum fluoride, of the flux-type coating is 575°C. However, it has been found that the flux-type coating on the particles displays a liquidus temperature of 540°C, which is significantly lower than would be expected, indicating that the metal braze material and flux-type material react with each other during manufacture to give a lowering of the liquidus temperature, perhaps by inclusion of silicon into the coating structure to form one or more compounds within the flux-type coating. The metal braze particles are produced by atomization of the molten metal and °°- 2 0 react during manufacture with the molten fused salt mixture of potassium fluoride and aluminum fluoride.
It has been found that the flux-type coating does melt first and reacts with the surface of the substrate aluminum material to disrupt the oxide film at, and adjacent to, the point of contact of the particle with the surface. The flux-type material protects both the localized region of the substrate and the encapsulated particle from further oxidation on melting of the particle and allows the surface oxide films to be disrupted and absorbed by the flux-type material. The molten metal is drawn into the joint by capillary action to form a bond. The surface of the substrate is increased in silicon content whilst the quantity of molten metal produced in the joint region significantly exceeds the amount of metal supplied in the form of metal braze particles.
In the prior art, as exemplified by U.S. Patent No.
3,951,328, it is stated that it does not affect the resulting joint if the braze particles melt before the flux. However, it is believed by the Applicant that it is important for the flux-type coating on the metal particle to melt first in order to protect both the substrate and the encapsulated particle during heating and melting of the latter. It is believed that the lowering of the melting point of the coating is directly attributable to the manufacturing process of the coated particles whereby a molten coating is applied during manufacture of the aluminum-silicon alloy particles. It is A' believed that at least silicon and perhaps further aluminum diffuses into the coating to give the lowering of the eutectic temperature displayed in Figure 3. It is also believed that some flux-type material may be contained within the metal braze particles themselves.
It is further believed that the fused flux-type material which is formed from potassium fluoride and aluminum fluoride in proportions at approximately the eutectic composition is substantially potassium aluminum fluoride, KA1F4, with constituents which have been derived from the metal particle.
The method of aspects of the present invention allows the use of extruded tubes of various forms to replace the standard seam-welded clad alloy tubes used heretofore. Figure 5, for example, shows a cross-section of the type of extruded tube which it is possible to employ with the brazing method of aspects of the present invention where no cladding is required. Tubes of flattened oval section having internal strengthening ribs 30 may be employed. Such tubes have greater surface area to volume ratio and are able to give greater cooling effect. The presence of the internal ribs 30 limits the amount of flexure which can occur due to fluctuating water pressure in the radiator and thus precludes failure by fatigue of the tube.
A
onto the liquid resin after the resin layer has been applied. The result of either technique is to cause the aluminum material and flux-type material to adhere to the surface of the substrate only in those areas where it is desired. However, it is preferred to "dust" the coated powder particles onto the resin as the particles are not then entirely coated by the resin and the possibility of the flux-type material being subsequently harmed by the resin during heating is greatly reduced. Alternatively, the coated aluminum-based filler material particles may be applied by any suitable carrier medium including, for example, an aqueous slurry.
According to another aspect of the present invention, a method is provided for joining together two or more articles of aluminum-based material, the method comprising the steps of applying a layer of particles of an aluminum alloy filler material, the particles having a coating of a flux-type material, i.e., a compound of potassium fluoride and aluminum fluoride together with, or also with, other inorganic flux-type materials, to at least one of the articles such that the particles are retained at, or adjacent to, at least a part of the joint between the articles, and heating to cause the flux-type material and the aluminum alloy filler material to melt and to form a brazed joint between the two or more articles.
By a variant of this method of an aspect of this invention, the aluminum braze particles may be produced by the steps of atomizing molten aluminum material, and coating the atomized aluminum braze material with inorganic molten the flux-type a g material during the production procedure, and raising the temperature of the substrate and the coated braze particles so as to cause the coated braze particles to melt and to form an adherent coating on the substrate.
By another variant of this method of an aspect of this invention, the aluminum braze particles may alternatively be produced by the steps of atomizing molten aluminum material, coating the atomized aluminum braze material with inorganic molten the flux-type material during the production procedure, and causing the coated aluminum braze particles to be retained on the substrate by being associated with a resin which is applied to the surface and raising the temperature of the substrate and the coated braze particles so as to cause the coated braze particles to melt and to form an adherent coating on the substrate.
By yet another aspect of this invention, a method is provided of joining together articles of an aluminum material by brazing, the method comprising the steps of applying, to a desired joint region of at least one of the articles, a layer of particles of an aluminum brazing material, the aluminum brazing material comprising particles of an aluminum alloy filler material, the particles being coated with a flux-type material comprising potassium fluoride and aluminum fluoride, the aluminum brazing material particles having been manufactured by the steps of atomizing molten aluminum material, coating the atomized aluminum braze material with inorganic molten flux-type material during the production procedure, causing the coated aluminum braze particles to be retained on the substrate by being associated with a resin which is applied to the surface and raising the temperature of the substrate and the coated braze particles so as to cause B:
°'~ 9 the coated braze particles to melt and to form an adherent coating on the substrate, releasing the coated aluminum brazing material particles on the surface of the at least one article by means of a resin which is applied to the surface of the at least one article, and raising the temperature of the articles and the coated aluminum brazing material particles so as to cause the particles to melt and form a brazed joint between the articles.
By one variant of this method of this aspect of this invention, the filler material includes silicon in the range from 5 to 50 wt % . By a variation thereof, the filler material includes silicon in the range from 7 to 15 wt % .
By another variant of this method of this aspect of this invention, or the above variant thereof, the aluminum alloy filler material is selected from the group of alloys consisting of aluminum-copper, aluminum-copper-magnesium, aluminum-zinc and aluminum plus rare earth metal.
By yet another variant of this method of this aspect of this invention, or the above variants thereof, the flux-type material comprises a fused mixture of aluminum fluoride and potassium fluoride. By a variation thereof, the flux-type material coating comprises from 40 to 50 wt% of potassium fluoride and from 60 to 50 wt% of aluminum fluoride.
By another variation thereof, the flux-type coating is of substantially eutectic composition with respect to potassium fluoride and aluminum fluoride. By still another variation thereof, the mixture of aluminum fluoride and potassium fluoride comprises cryolite.
By still another variant of this method of this aspect of this invention, or the above variants thereof, the flux-type coating also includes silicon.
B, By still a further variant of this method of this aspect of this invention, or the above variants thereof, the proportion of the flux-type coating to metal is from 5 to 30 wt % . By a variation thereof, the proportion is from 10 to 20 wt % .
By still yet another variant of this method of this aspect of this invention, or the 5 above variants thereof, the coated particles are mixed with the resin.
By yet another variant of this method of this aspect of this invention, or the above variants thereof, the coated particles are "dusted" onto the resin. By a variation thereof, the resin is applied dissolved in a solvent to liquefy it. By another variation thereof, the resin is an acrylic resin. By still a further variation thereof, the acrylic resin is 10 polymethylmethacrylate.
By yet a further variant of this method of this aspect of this invention, or the above variants thereof, the resin is removed by heating before the flux-type coating melts.
By a further variant of this method of this aspect of this invention, or the above variants thereof, the flux-type coating melts before the aluminum coating or the filler material.
By a still further variant of this method of this aspect of this invention, or the above variants thereof, the articles are unclad.
According to further aspects of this invention, the articles of aluminum-based material may be unclad.
The aluminum alloy filler material may contain silicon in the range from 5 to wt % . Preferably, where the alloy contains silicon, this may be in the range from 7 to 15 wt % .
Where the filler material is an aluminum-silicon alloy, it may also contain other alloying additions, e.g., copper and/or magnesium.
In one embodiment of the method of one aspect of the present invention, the composition of the aluminum alloy filler material includes silicon in the range from 9 to 12 wt% . Other aluminum alloys, e.g., aluminum-copper, aluminum-copper-magnesium, aluminum-zinc and aluminum plus rare-earth metals, for example, may be used.
Preferably, the compound of potassium fluoride and aluminum fluoride flux-type material comprises from 40 to 50 wt % of potassium fluoride and from 60 to 50 wt % of aluminum fluoride.
The proportion of flux-type material to metal in the braze particles may lie in the range from 5 to 30 wt % . A preferred range may be from 10 to 20 wt % of flux-type material to metal.
The layer of coated particles may be applied as a monolayer of particles.
As with the method of the first aspect of the present invention, in this method of a further aspect of the present invention, the coated particles may be adhered to the surface with a resin medium or with any other suitable carrier medium, the same considerations again applying.
The solidified resin allows more robust handling of any assemblies prior to brazing without the danger that the aluminum alloy filler material and the flux-type material will be shaken off.
The thickness and consistency of the applied resin layer may be controlled to govern the quantity of the coated metal powder particles which may be made to adhere to the substrate .
All the parameters of the resin discussed with reference to the method of the first aspect of the invention are applicable to the method of this second aspect of the invention.
Prior to coating the substrate of the articles to be joined with the liquid resin, at least the surfaces to be joined may first be cleaned by degreasing, followed by a step of, e.g., acid etching, to remove the oxide film which may be present on aluminum materials.
It must be stressed, however, that any method of retaining the braze particles in the required position may be °y employed, including trapping the particles between the surfaces to be joined.
It is a particular advantage of the method of aspects of the present invention that the methods have been found to be significantly more tolerant of surface contaminants, both inorganic and organic, than known brazing processes. In known processes, degreasing and acid etching to remove surface contaminants and the oxide film have been necessary.
Alternatively, ultrasonic degreasing which also disrupts the oxide film has been used. In the method of aspects of the present invention, it has been found that removal or disruption of the oxide film is not necessary.
It has been found that on melting, the fused potassium fluoride/aluminum fluoride flux-type coating on the aluminum silicon alloy particles reacts with the surface of the aluminum substrate to disrupt the oxide film and allows the molten particle contained within the coating to alloy with the metallic surface of the substrate. Tests conducted on articles brazed together by the method of the second aspect of this invention have shown substantial quantities of silicon present in the surface regions of the substrate. Furthermore, the quantity of filler material, as witnessed by the braze fillets present within the body of the joint and at the periphery of brazed joints, significantly exceeds the quantity of metal which was initially applied in the form of aluminum alloy braze particles.
A
The potassium fluoride and aluminum fluoride mixture may comprise the naturally occurring mineral, cryolite.
An advantage of the method of aspects of the present invention is that aluminum braze filler materials having lower melting points than used heretofore may now be used due to the lower melting point of the flux-type material.
A further advantage of the method of aspects of the present invention is that there is no possibility of the metal braze particles and flux-type material segregating since the two constituents are combined together, unlike the physical mixtures of flux and braze particles of the prior art.
The aluminum alloy braze material and the flux-type coating material both melt at a substantially lower temperature than that of the substrate aluminum-based material. Therefore, there is no need for the substrate articles to be clad with a lower melting point material prior to brazing. Tubes for radiators may now be formed by extrusion. Thus there is now no need to form weld seams which have different melting characteristics from the rest of the tube. Since the tubes may now be formed by extrusion, they may also have increased wall thickness and may also be formed with internal strengthening ribs to lessen the possibility of fatigue failure of the tubes.
In addition to the tubes being made by an extrusion technique, aluminum alloys of higher strength may also be used since the flux-type material used in the method of aspects of A
W" 15 the present invention is not adversely affected by alloying elements, e.g., magnesium, and neither is the substrate material adversely affected by the flux-type material.
(e) DESCRIPTION OF THE FIGURES
In the accompanying drawings, Figure 1 shows a schematic cross-section through part of two articles to be joined by a prior art brazing process;
Figure 2 shows part of the aluminum-silicon binary phase equilibrium diagram;
Figure 3 shows a part of the potassium fluoride-aluminum fluoride phase equilibrium diagram;
Figures 4A to 4F show a schematic step-by-step representation of the believed reaction of coated particles with a substrate during a brazing process; and Figure 5 shows a cross-section through an extruded radiator tube.
(f) ONE MODE FOR CARRYING OUT THE INVENTION
Referring now to Figure 1, two articles 10 and 12 are shown which are joined by brazing according to a prior art method. Each article comprises a core 14 of the substrate structural aluminum material, and which is clad on both sides with a layer 16 of a second aluminum alloy material having a substantially lower melting point than that of the core 14.
The surfaces of the two articles are degreased and cleaned by, r :, for example, etching to promote the adherence of a flux material. In the case of a vehicle radiator, the degreased and cleaned component parts, typically comprising airway fins, water tubes, tube plates and side water casings, are assembled together and dipped into a suspension of a flux in deionized water. The dipped assembly is removed from the flux bath and is dried to form a coating 18 of the flux on the clad surfaces . The assembly is then passed into a brazing oven where the temperature is raised to cause first the flux and then the clad surfaces to melt and fuse together to form the brazed joint. One problem which arises with this prior art method is that the flux is highly reactive and will react with contaminants, e.g., water vapour, in the brazing furnace atmosphere, thus negating the desired effect of the flux.
Furthermore, the clad alloy 16 must be metallurgically bonded to the substrate 14 to obviate the formation of an oxide film at the interface between the layers 14 and 16 which would prevent a sound joint being formed between the cladding 16 and the core 14 on melting of the cladding. Because of the need for a metallurgical bond between the core and the cladding, the use of roll-bonding in sheet form is virtually mandatory in order for high enough reductions to be achieved in the working process to secure a metallurgical bond. Thus, tubular items must be fabricated from sheet material by seam-welding causing the problems specified above relating to lowering of A
the melting point through the wall thickness of the tube due to the cladding material alloying with the core material.
Brazing trials were carried out with radiator components made of unclad aluminum alloy having a nominal composition of 0.6 Si/0.7 Fe/ 0.05-0.2 Cu/ 1-1.5 Mn/ balance A1. The components were degreased. After drying, the components were coated with a layer of acrylic resin, in this case polymethyl methacrylate which is dissolved in a toluene/trichloroethylene mixture, in those areas where a brazed joint was required.
Whilst the resin was still in the tacky state particles of metal power of composition 10 wt% Si/balance A1 and having a coating of a flux-type material of composition 40 to 50 wt%
potassium fluoride and 60 to 50 wt% of aluminum fluoride and near to the eutectic composition were dusted onto the surface with a powder spray gun. The coated powder particles had a size lying in the range from 60 to 250 ~,m. The coating thus formed was then dried with a warm air stream to dry the resin and cause the particles to adhere to the resin. The radiator components were then assembled together and passed through a brazing furnace having a nitrogen protective atmosphere. In a preheating zone of the furnace, the resin was driven off by the increasing temperature so that at the onset of melting of the coated particles, no resin remained. In driving off the resin coating, the heating rate should be sufficiently slow so as not to cause spalling of the resin coating. The furnace temperature was set at a nominal temperature which was sufficient to cause melting of the flux-type material and the metal powder particles but not of the substrate aluminum alloy.
Figures 4A to 4F show a schematic representation of what is believed to be the course of forming a brazed joint by the method of aspects of the present invention. Figure 4A shows the surface 40 of a tube 42 and portions of aluminum finning 44 to be brazed thereto for cooling purposes. A layer of resin 46 is applied to the surface 40 and coated particles 48 of aluminum-silicon braze alloy are dusted onto the liquid resin which is then dried. Figures 4B to 4E show the stages of reaction and melting of a coated particle with the surface 40. The surface 40 has an oxide layer 50 thereon, underneath which is the clean aluminum surface 52. On heating, the resin layer 46 dissociates and the products are removed by the flow of a nitrogen gas atmosphere to leave the particles 48 sitting on the surface of the oxide layer 50. As the temperature rises, the flux-type coating 54 melts at 540°C (Figure 4C) whilst the aluminum-silicon particle 56 therein remains solid.
The coating 54 reacts with the oxide layer 50 to disrupt it and allow the metal particle 56 to come into contact with the clean aluminum surface 52. It is believed that at this point substantial diffusion of the silicon from the particle into the substrate occurs. As the temperature rises to 575°C, the metal particle melts and begins to fuse with the surface 52 to alloy therewith and initially form a pit 58 of molten metal.
The silicon from the molten particle continues to diffuse into the molten pit (Figure 4D) and the area of molten surface 52 spreads laterally to j oin with molten areas formed at adj acent particles (Figure 4E). A complete layer of molten metal 60 is then formed (Figure 4F) which is drawn into the gap between the surface 40 and the finning 44 by capillary action. The cooling finning material 44 is similarly affected by the melting of the flux-type coating to allow metal to metal contact between the finning 44 and braze 56. The original flux-type material absorbs the oxide to form a residue with the solidified flux-type material on cooling.
It has been found, surprisingly, that the flux-type coating on the metal particles has a lower melting point than would be expected from the phase diagram shown in Figure 3.
From Figure 3 it may be seen that the melting temperature of the eutectic which is formed by the constituents, potassium fluoride and aluminum fluoride, of the flux-type coating is 575°C. However, it has been found that the flux-type coating on the particles displays a liquidus temperature of 540°C, which is significantly lower than would be expected, indicating that the metal braze material and flux-type material react with each other during manufacture to give a lowering of the liquidus temperature, perhaps by inclusion of silicon into the coating structure to form one or more compounds within the flux-type coating. The metal braze particles are produced by atomization of the molten metal and °°- 2 0 react during manufacture with the molten fused salt mixture of potassium fluoride and aluminum fluoride.
It has been found that the flux-type coating does melt first and reacts with the surface of the substrate aluminum material to disrupt the oxide film at, and adjacent to, the point of contact of the particle with the surface. The flux-type material protects both the localized region of the substrate and the encapsulated particle from further oxidation on melting of the particle and allows the surface oxide films to be disrupted and absorbed by the flux-type material. The molten metal is drawn into the joint by capillary action to form a bond. The surface of the substrate is increased in silicon content whilst the quantity of molten metal produced in the joint region significantly exceeds the amount of metal supplied in the form of metal braze particles.
In the prior art, as exemplified by U.S. Patent No.
3,951,328, it is stated that it does not affect the resulting joint if the braze particles melt before the flux. However, it is believed by the Applicant that it is important for the flux-type coating on the metal particle to melt first in order to protect both the substrate and the encapsulated particle during heating and melting of the latter. It is believed that the lowering of the melting point of the coating is directly attributable to the manufacturing process of the coated particles whereby a molten coating is applied during manufacture of the aluminum-silicon alloy particles. It is A' believed that at least silicon and perhaps further aluminum diffuses into the coating to give the lowering of the eutectic temperature displayed in Figure 3. It is also believed that some flux-type material may be contained within the metal braze particles themselves.
It is further believed that the fused flux-type material which is formed from potassium fluoride and aluminum fluoride in proportions at approximately the eutectic composition is substantially potassium aluminum fluoride, KA1F4, with constituents which have been derived from the metal particle.
The method of aspects of the present invention allows the use of extruded tubes of various forms to replace the standard seam-welded clad alloy tubes used heretofore. Figure 5, for example, shows a cross-section of the type of extruded tube which it is possible to employ with the brazing method of aspects of the present invention where no cladding is required. Tubes of flattened oval section having internal strengthening ribs 30 may be employed. Such tubes have greater surface area to volume ratio and are able to give greater cooling effect. The presence of the internal ribs 30 limits the amount of flexure which can occur due to fluctuating water pressure in the radiator and thus precludes failure by fatigue of the tube.
A
Claims (25)
1. A method of forming an adherent aluminum material coating on a substrate having a higher melting point than said aluminum braze coating material, said aluminum braze coating material being formed of aluminum braze particles which are coated with an inorganic flux-type material which is selected from the group consisting of a compound of potassium fluoride and aluminum fluoride together with, or also with, other inorganic flux-type materials, said method including the steps of:
(A) producing said aluminum braze particles by the steps of atomizing molten aluminum material, and coating said atomized aluminum braze material with molten said inorganic flux-type material during said production procedure;
and then (B) raising the temperature of said substrate and said coated braze particles so as to cause said coated braze particles to melt and to form an adherent coating on said substrate.
(A) producing said aluminum braze particles by the steps of atomizing molten aluminum material, and coating said atomized aluminum braze material with molten said inorganic flux-type material during said production procedure;
and then (B) raising the temperature of said substrate and said coated braze particles so as to cause said coated braze particles to melt and to form an adherent coating on said substrate.
2. A method of forming an adherent aluminum material coating on a substrate having a higher melting point than said aluminum braze coating material, said aluminum braze coating material being formed of aluminum braze particles which are coated with an inorganic flux-type material which is selected from the group consisting of a compound of potassium fluoride and aluminum fluoride together with, or also with, other inorganic flux-type materials, said method including the steps of:
(A) producing said aluminum braze particles by the steps of atomizing molten aluminum material, and coating said atomized aluminum braze material with said inorganic molten flux-type material during said production procedure;
(B) causing said coated aluminum braze particles to be retained on said substrate by being associated with a resin which is applied to said surface; and then (C) raising the temperature of said substrate and said coated braze particles so as to cause said coated braze particles to melt and to form an adherent coating on said substrate.
(A) producing said aluminum braze particles by the steps of atomizing molten aluminum material, and coating said atomized aluminum braze material with said inorganic molten flux-type material during said production procedure;
(B) causing said coated aluminum braze particles to be retained on said substrate by being associated with a resin which is applied to said surface; and then (C) raising the temperature of said substrate and said coated braze particles so as to cause said coated braze particles to melt and to form an adherent coating on said substrate.
3. A method according to claim 1 or claim 2, wherein said coating is an aluminized coating on a ferrous substrate.
4. A method according to claim 1, claim 2 or claim 3, wherein said coating is used as an intermediate brazing layer to join an article to said substrate.
5. A method of joining together two or more articles of aluminum-based material, said method comprising the steps of:
(A) applying a layer of aluminum braze particles of an aluminum alloy filler material, said aluminum braze particles having a coating of a first inorganic flux-type material which is selected from the group consisting of a compound of potassium fluoride and aluminum fluoride together with, or also with, other inorganic flux-type material, to at least one of said articles such that said particles are retained at, or adjacent to, the joint between said articles, said aluminum braze particles being produced by the steps of atomizing molten aluminum material, and coating said atomized aluminum braze material with molten said first inorganic flux-type material during said production procedure, and then raising the temperature of said substrate and said coated braze particles so as to cause said coated braze particles to melt and to form an adherent coating on said substrate; and (B) heating to cause said first flux-type material and said aluminum alloy filler material to melt and to form a brazed joint between said two or more articles.
(A) applying a layer of aluminum braze particles of an aluminum alloy filler material, said aluminum braze particles having a coating of a first inorganic flux-type material which is selected from the group consisting of a compound of potassium fluoride and aluminum fluoride together with, or also with, other inorganic flux-type material, to at least one of said articles such that said particles are retained at, or adjacent to, the joint between said articles, said aluminum braze particles being produced by the steps of atomizing molten aluminum material, and coating said atomized aluminum braze material with molten said first inorganic flux-type material during said production procedure, and then raising the temperature of said substrate and said coated braze particles so as to cause said coated braze particles to melt and to form an adherent coating on said substrate; and (B) heating to cause said first flux-type material and said aluminum alloy filler material to melt and to form a brazed joint between said two or more articles.
6. The method of claim 5 wherein said aluminum braze particles are produced by the additional step of causing said coated aluminum braze particles to be retained on said substrate by being associated with a resin which is applied to said surface.
7. A method of joining together articles of an aluminum material by brazing, said method comprising the steps of:
(A) applying, to a desired joint region of at least one of said articles, a layer of particles of an aluminum brazing material, said aluminum brazing material comprising particles of an aluminum alloy filler material, said particles being coated with an inorganic flux-type material comprising potassium fluoride and aluminum fluoride, said aluminum brazing material particles having been manufactured by the steps of atomizing molten aluminum material, coating said atomized aluminum braze material with molten said inorganic flux-type material during said production procedure, causing said coated aluminum braze particles to be retained on said substrate by being associated with a resin which is applied to said surface, and raising the temperature of said substrate and said coated braze particles so as to cause said coated braze particles to melt and to form an adherent coating on said substrate;
(B) retaining said coated aluminum brazing material particles on the surface of said at least one article by means of said resin which is applied to the surface of said at least one article; and (C) raising the temperature of said articles and said coated aluminum brazing material particles so as to cause said particles to melt and to form a brazed joint between said articles.
(A) applying, to a desired joint region of at least one of said articles, a layer of particles of an aluminum brazing material, said aluminum brazing material comprising particles of an aluminum alloy filler material, said particles being coated with an inorganic flux-type material comprising potassium fluoride and aluminum fluoride, said aluminum brazing material particles having been manufactured by the steps of atomizing molten aluminum material, coating said atomized aluminum braze material with molten said inorganic flux-type material during said production procedure, causing said coated aluminum braze particles to be retained on said substrate by being associated with a resin which is applied to said surface, and raising the temperature of said substrate and said coated braze particles so as to cause said coated braze particles to melt and to form an adherent coating on said substrate;
(B) retaining said coated aluminum brazing material particles on the surface of said at least one article by means of said resin which is applied to the surface of said at least one article; and (C) raising the temperature of said articles and said coated aluminum brazing material particles so as to cause said particles to melt and to form a brazed joint between said articles.
8. A method according to any one of claims 5 to 7, wherein said filler material includes silicon in the range from 5 to 50 wt%.
9. A method according to claim 9, wherein said filler material includes silicon in the range from 7 to 15 wt %.
10. A method according to any one of claims 5 to 9, wherein said aluminum alloy filler material is selected from the group of alloys consisting of aluminum-copper, aluminum-copper-magnesium, aluminum-zinc and aluminum plus rare earth metal.
11. A method according to any one of claims 1 to 10, wherein said flux-type material consists of a fused mixture of aluminum fluoride and potassium fluoride.
12. A method according to claim 11, wherein said flux-type material coating comprises from 40 to 50 wt % of potassium fluoride and from 60 to 50 wt % of aluminum fluoride.
13. A method according to claim 11, wherein said flux-type coating is of substantially eutectic composition with respect to potassium fluoride and aluminum fluoride.
14. A method according to claim 11, wherein said mixture of aluminum fluoride and potassium fluoride comprises cryolite.
15. A method according to any one of claims 1 to 14, wherein said flux-type coating also includes silicon.
16. A method according to any one of claims 1 to 15, wherein the proportion of said flux-type coating to metal is from 5 to 30 wt %.
17. A method according to claim 16, wherein the proportion is from 10 to 20 wt%.
18. A method according to any one of claims 2 to 4, and claims 6 to 17, wherein said coated particles are mixed with said resin.
19. A method according to claim 18, wherein said coated particles are "dusted"
onto said resin.
onto said resin.
20. A method according to claim 18 or claim 19, wherein said resin is applied dissolved in a solvent to liquefy it.
21. A method according to any one of claims 18 to 20, wherein said resin is an acrylic resin.
22. A method according to claim 21, wherein said acrylic resin is polymethylmethacrylate.
23. A method according to any one of claims 18 to 22, wherein said resin is removed by heating before said flux-type coating melts.
24. A method according to any one of claims 5 to 23, wherein said flux-type coating melts before said aluminum coating or filler material.
25. A method according to any one of claims 5 to 24, wherein said articles are unclad.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB939312328A GB9312328D0 (en) | 1993-06-15 | 1993-06-15 | A method of brazing |
| GB9312328.9 | 1993-06-15 | ||
| PCT/GB1994/001261 WO1994029072A1 (en) | 1993-06-15 | 1994-06-10 | A method of brazing |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2165338A1 CA2165338A1 (en) | 1994-12-22 |
| CA2165338C true CA2165338C (en) | 2002-11-12 |
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|---|---|---|---|
| CA002165338A Expired - Fee Related CA2165338C (en) | 1993-06-15 | 1994-06-10 | A method of brazing |
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| US (1) | US5755374A (en) |
| EP (1) | EP0703846B1 (en) |
| JP (1) | JP3330609B2 (en) |
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| CN (1) | CN1043415C (en) |
| AU (1) | AU681155B2 (en) |
| BR (1) | BR9406824A (en) |
| CA (1) | CA2165338C (en) |
| CZ (1) | CZ290659B6 (en) |
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| ES (1) | ES2098955T3 (en) |
| GB (1) | GB9312328D0 (en) |
| IN (1) | IN181717B (en) |
| TW (1) | TW262420B (en) |
| WO (1) | WO1994029072A1 (en) |
| ZA (1) | ZA944186B (en) |
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- 1993-06-15 GB GB939312328A patent/GB9312328D0/en active Pending
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- 1994-06-10 JP JP50149795A patent/JP3330609B2/en not_active Expired - Lifetime
- 1994-06-10 EP EP94917725A patent/EP0703846B1/en not_active Expired - Lifetime
- 1994-06-10 BR BR9406824A patent/BR9406824A/en not_active IP Right Cessation
- 1994-06-10 AU AU69326/94A patent/AU681155B2/en not_active Ceased
- 1994-06-10 DE DE69402198T patent/DE69402198T2/en not_active Expired - Fee Related
- 1994-06-10 CA CA002165338A patent/CA2165338C/en not_active Expired - Fee Related
- 1994-06-10 CN CN94192399A patent/CN1043415C/en not_active Expired - Fee Related
- 1994-06-10 CZ CZ19953290A patent/CZ290659B6/en not_active IP Right Cessation
- 1994-06-10 ES ES94917725T patent/ES2098955T3/en not_active Expired - Lifetime
- 1994-06-10 WO PCT/GB1994/001261 patent/WO1994029072A1/en active IP Right Grant
- 1994-06-10 KR KR1019950705645A patent/KR100264282B1/en not_active IP Right Cessation
- 1994-06-14 IN IN451CA1994 patent/IN181717B/en unknown
- 1994-06-14 ZA ZA944186A patent/ZA944186B/en unknown
- 1994-06-20 TW TW083105562A patent/TW262420B/zh not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| WO1994029072A1 (en) | 1994-12-22 |
| CZ329095A3 (en) | 1996-05-15 |
| DE69402198D1 (en) | 1997-04-24 |
| ZA944186B (en) | 1995-02-08 |
| CZ290659B6 (en) | 2002-09-11 |
| AU6932694A (en) | 1995-01-03 |
| ES2098955T3 (en) | 1997-05-01 |
| EP0703846A1 (en) | 1996-04-03 |
| IN181717B (en) | 1998-09-05 |
| JP3330609B2 (en) | 2002-09-30 |
| AU681155B2 (en) | 1997-08-21 |
| TW262420B (en) | 1995-11-11 |
| CN1125412A (en) | 1996-06-26 |
| JPH08511201A (en) | 1996-11-26 |
| BR9406824A (en) | 1996-03-26 |
| CA2165338A1 (en) | 1994-12-22 |
| GB9312328D0 (en) | 1993-07-28 |
| KR100264282B1 (en) | 2000-08-16 |
| CN1043415C (en) | 1999-05-19 |
| US5755374A (en) | 1998-05-26 |
| DE69402198T2 (en) | 1997-10-30 |
| EP0703846B1 (en) | 1997-03-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |