EP1771601A1 - Method of forming a conversion layer on an aluminium alloy product prior to fluxless brazing - Google Patents

Method of forming a conversion layer on an aluminium alloy product prior to fluxless brazing

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Publication number
EP1771601A1
EP1771601A1 EP05793591A EP05793591A EP1771601A1 EP 1771601 A1 EP1771601 A1 EP 1771601A1 EP 05793591 A EP05793591 A EP 05793591A EP 05793591 A EP05793591 A EP 05793591A EP 1771601 A1 EP1771601 A1 EP 1771601A1
Authority
EP
European Patent Office
Prior art keywords
treatment
solution
conversion layer
temperature
flux
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05793591A
Other languages
German (de)
French (fr)
Inventor
Sylvestre Safrany
Michel Mediouni
Sylvain Henry
Sandrine Dulac
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Constellium Issoire SAS
Original Assignee
Alcan Rhenalu SAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alcan Rhenalu SAS filed Critical Alcan Rhenalu SAS
Publication of EP1771601A1 publication Critical patent/EP1771601A1/en
Withdrawn legal-status Critical Current

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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
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex 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
    • B23K1/00—Soldering, e.g. brazing, or unsoldering
    • B23K1/20—Preliminary treatment of work or areas to be soldered, e.g. in respect of a galvanic coating
    • 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
    • B23K2103/00—Materials to be soldered, welded or cut
    • B23K2103/08—Non-ferrous metals or alloys
    • B23K2103/10—Aluminium or alloys thereof
    • 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
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y10T428/2933—Coated or with bond, impregnation or core
    • Y10T428/294—Coated or with bond, impregnation or core including metal or compound thereof [excluding glass, ceramic and asbestos]
    • Y10T428/2951—Metal with weld modifying or stabilizing coating [e.g., flux, slag, producer, etc.]

Definitions

  • the invention relates to a solder joining method without product flow in
  • Aluminum alloy such as sheets, strips or tubes, the absence of flux being permitted by a prior treatment for forming a surface conversion layer of said aluminum alloy products. These products are used in particular in the manufacture of heat exchangers, in particular those used for engine cooling and air conditioning of vehicle interiors.
  • brazing process currently the most used for the manufacture of heat exchangers is brazing in a controlled atmosphere with a non-corrosive flow, called Nocolok® brazing. This process gradually replaces the vacuum brazing used previously but which required expensive installations both in initial investment and maintenance.
  • the first category concerns soldering processes without flux. Processes using products made of aluminum alloy (s) coated with nickel deposition (see for example WO 02/07928 by Corus Aluminum Walz organization) and the addition of sodium to plating alloy described in WO 01/98019 from Kaiser Alurninum & Chemical Corporation.
  • the second category concerns so-called pre-fluxed strips, that is to say strips having a surface layer containing the soldering flux.
  • the flux is mechanically inlaid into the strip during rolling.
  • the flux is incorporated in a binder and everything is deposited on the aluminum alloy strip.
  • US Pat. No. 6,344,237 to Alcoa Inc. the flux is embedded in the metal by high speed spraying.
  • Ford Global Technologies patent EP 1067213 describes the treatment of an aluminum alloy strip in an aqueous solution of 2 to 25% by weight of KF at a temperature of between 32 and 100 ° C. for at least 5 seconds. This operation would create on the surface of the metal a conversion layer which contains either substantially K 3 AlF 6 or mainly K 3 AlF 6 and in addition a small proportion of KAlF 4 .
  • the subject of the invention is therefore a soldering process without flux of products such as sheets, strips or tubes of heat exchangers, characterized in that, to avoid the use of said flux, said alloy products ( ) of aluminum, are previously subjected to a formation treatment, on all or part of their surface, of a conversion layer using a solution containing K + ions and F " and one or more acid (s) in an amount such that the pH of the solution is less than
  • said treatment is preceded by an alkaline pickling.
  • the acid is preferably sulfuric acid at a concentration of between 10 and
  • the treatment is preferably at a temperature of between 30 and
  • the K + and F " ions are advantageously provided in the form of KF or in the form of a KCl + NH 5 F 2 mixture.
  • Figures 1a and 1b show, respectively in top view and side view, the V-shaped specimens used in the examples for evaluating the solderability.
  • the invention consists in modifying the treatment solution described in patent EP 1067213 to obtain on all or part of the surface of products made of aluminum alloy (s), sheets, strips or tubes, used in the manufacture of heat exchangers , in particular of motor vehicles, a deposit allowing their brazing without additional addition of flux.
  • This modification consists in an acidification of the bath, without using the hydrofluoric acid which is mentioned in the application EP 0140267 of Toyota Chuo and which poses too great toxicity problems.
  • the invention consists in adding to the KF solution described in the aforementioned patent sulfuric acid at a level of 10 to 40 g / l. It would also be possible to use nitric acid HNO 3 at a concentration of 20 to 50% by volume, but this solution is not preferred because of the possible emission of nitrous vapors. May also be used hydrochloric acid HCl (typically at a concentration of 1 to 50 g / l) 5 one or more organic acids, or any combination thereof inorganic or organic acids which makes it possible to obtain a pH below 3, a zone favorable for the dissolution of aluminum.
  • the other treatment conditions recommended in the patent may be retained.
  • the minimum temperature value makes it possible to ensure sufficiently strong reaction kinetics.
  • Working at room temperature is also possible, with an increase in the duration of the treatment.
  • An alternative is to bring the F ' and K + ions through, for example, NH 5 F 2 and KCl solutions, always with acidification of the solution.
  • a possible surface preparation, prior to treatment, has the sole purpose of having a clean surface. If the metal resulting from the industrial processing is not noticeably fatty, a simple thermal degreasing is sufficient; for added safety, it is possible to add, for example, an alkaline pickling soda or potash.
  • solder alloy layer 4045 of thickness representing 10% of the total thickness.
  • Treatment 1 (according to Patent EP 1067213):
  • Treatment 3 (according to the invention):
  • Treatment 4 replacement of KF with NaF, with acidification: Degreasing the surface with acetone,
  • the test piece depicted in FIG. 1 was used to evaluate the ability to solder without flux of the materials having undergone these various treatments.
  • the "V" consists of a bare strip of alloy 3003, in the state H24, and of thickness 0.3 mm.
  • a degreasing treatment of 15 minutes at 250 ° C. is applied to the metal to be brazed. No other surface preparation is used and in particular no flux is deposited. Brazing is performed in a double-walled glass furnace that displays liquid solder movements and joint formation during processing.
  • the thermal cycle consists of a temperature rise up to 600 ° C with a ramp of about 20 ° C / min, a 2 minute hold at 600 ° C, and a descent to a speed of about 30 ° C / min. The whole is carried out under continuous nitrogen sweep, with a flow rate of 8 l / min.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Abstract

The invention relates to a method of assembling aluminium alloy products, such as sheets, strips or tubes, by means of fluxless brazing, whereby the absence of flux is made possible owing to an earlier treatment comprising the formation of a conversion layer on the surface of said products using a solution containing K<sup

Description

PROCEDE DE FORMATION D ' UNE COUCHE DE CONVERSION SUR UN PRODUIT EN ALLIAGE D ' ALUM INIUM AVANT LE PROCEDE DE BRASAGE SANS FLUXMETHOD OF FORMING A CONVERSION LAYER ON ALUMINUM ALLOY PRODUCT BEFORE THE FLOW - FREE SOLDER PROCESS
Domaine de l'inventionField of the invention
L'invention concerne un procédé d'assemblage par brasage sans flux de produits enThe invention relates to a solder joining method without product flow in
10 alliage(s) d'aluminium tels que des tôles, bandes ou tubes, l'absence de flux étant permise par un traitement préalable de formation d'une couche de conversion en surface desdits produits en alliage(s) d'aluminium. Ces produits sont utilisés notamment dans la fabrication des échangeurs de chaleur, en particulier ceux servant au refroidissement des moteurs et à la climatisation des habitacles des véhiculesAluminum alloy (s) such as sheets, strips or tubes, the absence of flux being permitted by a prior treatment for forming a surface conversion layer of said aluminum alloy products. These products are used in particular in the manufacture of heat exchangers, in particular those used for engine cooling and air conditioning of vehicle interiors.
15 automobiles.15 automobiles.
Etat de la techniqueState of the art
Le procédé de brasage actuellement le plus utilisé pour la fabrication des échangeurs 20 thermiques est le brasage sous atmosphère contrôlée avec flux non corrosif, dit brasage Nocolok®. Ce procédé remplace progressivement le brasage sous vide utilisé auparavant mais qui nécessitait des installations coûteuses à la fois en investissement initial et en maintenance.The brazing process currently the most used for the manufacture of heat exchangers is brazing in a controlled atmosphere with a non-corrosive flow, called Nocolok® brazing. This process gradually replaces the vacuum brazing used previously but which required expensive installations both in initial investment and maintenance.
L'inconvénient principal du procédé Nocolok® réside dans la nécessité de déposer 25 sur le métal, avant brasage, un composé appelé « flux » et constitué de fluoro- aluminates de potassium. Celui-ci a pour but de détruire la couche d'oxyde superficielle présente sur les alliages d'aluminium, un peu avant le début de fusion du placage. Ainsi, le métal liquide ne sera pas retenu par cette pellicule et pourra venir mouiller convenablement les surfaces à assembler et former des joints 30 suffisamment larges et résistants. L'utilisation de ce produit, qui se présente sous la forme d'une poudre, par les équipementiers de l'automobile pose un certain nombre de problèmes : elle engendre notamment une dispersion relativement importante de poussières dans les ateliers. De nombreuses publications ou demandes de brevets proposent des solutions pour s'affranchir de ce problème. On peut les classer dans deux grandes catégories :The main disadvantage of the Nocolok® process lies in the need to deposit on the metal, before soldering, a compound called "flux" and consisting of potassium fluoromelates. The purpose of this is to destroy the surface oxide layer on the aluminum alloys, a little before the beginning of melting of the veneer. Thus, the liquid metal will not be retained by this film and may appropriately wet the surfaces to be assembled and form sufficiently large and resistant joints. The use of this product, which is in the form of a powder, by automotive equipment manufacturers poses a number of problems: it causes in particular a relatively large dispersion of dust in the workshops. Many publications or patent applications offer solutions to overcome this problem. They can be classified into two broad categories:
La première catégorie concerne les procédés de brasage sans flux. On peut citer dans ce domaine les procédés utilisant des produits en alliage(s) d'aluminium revêtus d'un dépôt de nickel (voir par exemple WO 02/07928 de Corus Aluminium Walzprodukte), ainsi que l'ajout de sodium dans l'alliage de placage décrit dans la demande WO 01/98019 de Kaiser Alurninum & Chemical Corporation. La seconde catégorie concerne ce qu'on appelle les bandes pré-fluxées, c'est-à-dire des bandes comportant une couche superficielle contenant le flux de brasage. Dans le brevet US 6,120,848 de Ford Motor Company, le flux est incrusté mécaniquement dans la bande lors du laminage. Dans les demandes WO 00/64626 de Corus Aluminium, WO 02/087814 - WO 03/037559 de Norsk Hydro, ou encore WO 03/089176 d'Alcoa Inc. et American Inks and Coatings Corporation, le flux est incorporé dans un liant et le tout est déposé sur la bande en alliage d'aluminium. Dans le brevet US 6,344,237 d'Alcoa Inc. le flux est incrusté dans le métal par pulvérisation à forte vitesse.The first category concerns soldering processes without flux. Processes using products made of aluminum alloy (s) coated with nickel deposition (see for example WO 02/07928 by Corus Aluminum Walzprodukte) and the addition of sodium to plating alloy described in WO 01/98019 from Kaiser Alurninum & Chemical Corporation. The second category concerns so-called pre-fluxed strips, that is to say strips having a surface layer containing the soldering flux. In US Pat. No. 6,120,848 to Ford Motor Company, the flux is mechanically inlaid into the strip during rolling. In the applications WO 00/64626 of Corus Aluminum, WO 02/087814 - WO 03/037559 of Norsk Hydro, or WO 03/089176 of Alcoa Inc. and American Inks and Coatings Corporation, the flux is incorporated in a binder and everything is deposited on the aluminum alloy strip. In US Pat. No. 6,344,237 to Alcoa Inc. the flux is embedded in the metal by high speed spraying.
Le brevet EP 1067213 de Ford Global Technologies décrit le traitement d'une bande en alliage d'aluminium dans une solution aqueuse de 2 à 25 % en poids de KF à une température comprise entre 32 et 1000C pendant au moins 5 secondes. Cette opération permettrait de créer à la surface du métal une couche de conversion qui contient soit quasi essentiellement K3AlF6, soit principalement K3AlF6 et en plus une faible proportion de KAlF4.Ford Global Technologies patent EP 1067213 describes the treatment of an aluminum alloy strip in an aqueous solution of 2 to 25% by weight of KF at a temperature of between 32 and 100 ° C. for at least 5 seconds. This operation would create on the surface of the metal a conversion layer which contains either substantially K 3 AlF 6 or mainly K 3 AlF 6 and in addition a small proportion of KAlF 4 .
La demanderesse a constaté que la mise en œuvre du procédé décrit dans ce brevet ne permettait pas d'obtenir un brasage sans flux satisfaisant.The Applicant has found that the implementation of the method described in this patent did not allow to obtain a brazing without satisfactory flow.
Objet de l'inventionObject of the invention
L'invention a donc pour objet un procédé d'assemblage par brasage sans flux de produits tels que des tôles, bandes ou tubes d'échangeurs thermiques, caractérisé en ce que, pour éviter l'utilisation dudit flux, lesdits produits en alliage(s) d'aluminium, sont préalablement soumis à un traitement de formation, sur tout ou partie de leur surface, d'une couche de conversion à l'aide d'une solution contenant des ions K+ et F" et un ou plusieurs acide(s) en quantité telle que le pH de la solution soit inférieur àThe subject of the invention is therefore a soldering process without flux of products such as sheets, strips or tubes of heat exchangers, characterized in that, to avoid the use of said flux, said alloy products ( ) of aluminum, are previously subjected to a formation treatment, on all or part of their surface, of a conversion layer using a solution containing K + ions and F " and one or more acid (s) in an amount such that the pH of the solution is less than
3.3.
Selon un mode de réalisation avantageuse, ledit traitement est précédé d'un décapage alcalin. L'acide est de préférence l'acide sulfurique à une concentration comprise entre 10 etAccording to an advantageous embodiment, said treatment is preceded by an alkaline pickling. The acid is preferably sulfuric acid at a concentration of between 10 and
40 g/1. Le traitement se fait de préférence à une température comprise entre 30 et40 g / 1. The treatment is preferably at a temperature of between 30 and
100°C.100 ° C.
Les ions K+ et F" sont avantageusement apportés sous forme de KF ou encore sous forme d'un mélange KCl + NH5F2.The K + and F " ions are advantageously provided in the form of KF or in the form of a KCl + NH 5 F 2 mixture.
Description des figuresDescription of figures
Les figures la et Ib représentent, respectivement en vue de dessus et vue de côté, les éprouvettes en V utilisées dans les exemples pour évaluer l'aptitude au brasage.Figures 1a and 1b show, respectively in top view and side view, the V-shaped specimens used in the examples for evaluating the solderability.
Description de l'inventionDescription of the invention
L'invention consiste à modifier la solution de traitement décrite dans le brevet EP 1067213 pour obtenir sur tout ou partie de la surface de produits en alliage(s) d'aluminium, tôles, bandes ou tubes, utilisés dans la fabrication d'échangeurs thermiques, notamment de véhicules automobiles, un dépôt permettant leur brasage sans adjonction supplémentaire de flux. Cette modification consiste en une acidification du bain, sans utiliser l'acide fluorhydrique qui est mentionné dans la demande EP 0140267 de Toyota Chuo et qui pose des problèmes de toxicité trop importants.The invention consists in modifying the treatment solution described in patent EP 1067213 to obtain on all or part of the surface of products made of aluminum alloy (s), sheets, strips or tubes, used in the manufacture of heat exchangers , in particular of motor vehicles, a deposit allowing their brazing without additional addition of flux. This modification consists in an acidification of the bath, without using the hydrofluoric acid which is mentioned in the application EP 0140267 of Toyota Chuo and which poses too great toxicity problems.
L'invention consiste à ajouter dans la solution de KF décrite dans le brevet précité de l'acide sulfurique à hauteur de 10 à 40 g/1. Il serait également possible d'utiliser l'acide nitrique HNO3 à une concentration de 20 à 50% en volume, mais cette solution n'est pas préférée du fait de l'émission possible de vapeurs nitreuses. On peut également utiliser l'acide chlorhydrique HCl (typiquement à une concentration de 1 à 50g/l)5 un ou plusieurs acides organiques, ou encore toute combinaison de ces acides minéraux ou organiques qui permette d'obtenir un pH inférieur à 3, zone favorable à la dissolution de l'aluminium.The invention consists in adding to the KF solution described in the aforementioned patent sulfuric acid at a level of 10 to 40 g / l. It would also be possible to use nitric acid HNO 3 at a concentration of 20 to 50% by volume, but this solution is not preferred because of the possible emission of nitrous vapors. May also be used hydrochloric acid HCl (typically at a concentration of 1 to 50 g / l) 5 one or more organic acids, or any combination thereof inorganic or organic acids which makes it possible to obtain a pH below 3, a zone favorable for the dissolution of aluminum.
Il est préférable en revanche d'éviter l'acide phosphorique, pour des raisons de compatibilité avec le procédé de brasage pour lequel l'effet néfaste du phosphore est connu.On the other hand, it is preferable to avoid phosphoric acid, for reasons of compatibility with the brazing process for which the harmful effect of phosphorus is known.
Les autres conditions de traitement préconisées dans le brevet peuvent être conservées. La valeur minimale de température permet d'assurer une cinétique de réaction suffisamment forte. Le travail à température ambiante est également envisageable, moyennant une augmentation de la durée du traitement. Une alternative consiste à amener les ions F' et K+ par le biais, par exemple, de solutions de NH5F2 et KCl, toujours avec acidification de la solution. Une préparation éventuelle de surface, préalable au traitement, a pour seul objectif de disposer d'une surface propre. Si le métal issu de la transformation industrielle n'est pas notablement gras, un simple dégraissage thermique est suffisant ; pour plus de sécurité, il est possible d'ajouter, par exemple, un décapage alcalin à la soude ou à la potasse.The other treatment conditions recommended in the patent may be retained. The minimum temperature value makes it possible to ensure sufficiently strong reaction kinetics. Working at room temperature is also possible, with an increase in the duration of the treatment. An alternative is to bring the F ' and K + ions through, for example, NH 5 F 2 and KCl solutions, always with acidification of the solution. A possible surface preparation, prior to treatment, has the sole purpose of having a clean surface. If the metal resulting from the industrial processing is not noticeably fatty, a simple thermal degreasing is sufficient; for added safety, it is possible to add, for example, an alkaline pickling soda or potash.
ExemplesExamples
On a réalisé les différents traitements sur des bandes en alliage 3916 de la demanderesse de composition ( % en poids) :The various treatments were carried out on alloy strips 3916 of the Applicant's composition (% by weight):
plaquées sur les deux faces d'une couche d'alliage de brasage 4045 d'épaisseur représentant 10 % de l'épaisseur totale.plated on both sides with a solder alloy layer 4045 of thickness representing 10% of the total thickness.
Traitement 1 (selon le brevet EP 1067213) :Treatment 1 (according to Patent EP 1067213):
Dégraissage de la surface à l'acétone, - Décapage dans une solution de KOH à 10 g/1, à une température de 60°C et pendant 45 s, sans neutralisation, ni rinçage,Degreasing the surface with acetone, - Pickling in a solution of KOH at 10 g / l, at a temperature of 60 ° C and for 45 s, without neutralization or rinsing,
- Immersion de l'échantillon dans une solution de KF à 30 g/1, à une température de 60°C et pendant 30 s.- Immersion of the sample in a solution of KF at 30 g / l, at a temperature of 60 ° C and for 30 s.
Traitement 1-bis :Treatment 1-bis:
- Même traitement que précédemment mais en utilisant une solution de KF à 50 g/1.- Same treatment as above but using a solution of KF at 50 g / 1.
Traitement 2 (remplacement de KF par NaF) :Treatment 2 (replacement of KF with NaF):
- Dégraissage de la surface à l'acétone,- Degreasing the surface with acetone,
- Décapage dans une solution de KOH à 10 g/1, à une température de 600C et pendant 45 s, sans neutralisation, ni rinçage,- Pickling in a solution of KOH at 10 g / l, at a temperature of 60 ° C. and for 45 s, without neutralization or rinsing,
- Immersion de l'échantillon dans une solution de NaF à 30 g/1, à une température de 6O0C et pendant 30 s.Immersion of the sample in a solution of NaF at 30 g / l at a temperature of 60 ° C. and for 30 s.
Traitement 2-bis (remplacement de KF par NaF) :2-bis treatment (replacement of KF with NaF):
- Même traitement que le traitement 2, mais en utilisant une solution de NaF à 50 g/1.Same treatment as treatment 2, but using a solution of NaF at 50 g / l.
Traitement 3 (selon l'invention) :Treatment 3 (according to the invention):
- Dégraissage de la surface à l'acétone,- Degreasing the surface with acetone,
- Décapage dans une solution de KOH à 10 g/1, à une température de 6O0C et pendant 45 s, sans neutralisation, ni rinçage,- Pickling in a solution of KOH at 10 g / l, at a temperature of 60 ° C. and for 45 s, without neutralization or rinsing,
- Immersion de l'échantillon dans une solution de KF à 30 g/1 + H2SO4 à 30 g/1, à une température de 600C et pendant 30 s.Immersion of the sample in a solution of KF at 30 g / l + H 2 SO 4 at 30 g / l at a temperature of 60 ° C. and for 30 s.
Traitement 4 (remplacement de KF par NaF, avec acidification) : Dégraissage de la surface à l'acétone,Treatment 4 (replacement of KF with NaF, with acidification): Degreasing the surface with acetone,
- Décapage dans une solution de KOH à 10 g/1, à une température de 60°C et pendant 45 s, sans neutralisation, ni rinçage, - Immersion de l'échantillon dans une solution de NaF à 30 g/1 + H2SO4 à 30 g/1, à une température de 6O0C et pendant 30 s.- Pickling in a solution of KOH at 10 g / l, at a temperature of 60 ° C and for 45 s, without neutralization or rinsing, - Immersion of the sample in a solution of NaF at 30 g / 1 + H 2 SO 4 at 30 g / l, at a temperature of 60 ° C. and for 30 s.
Traitement S (selon l'invention) :Treatment S (according to the invention):
- Dégraissage de la surface à l'acétone,- Degreasing the surface with acetone,
- Décapage dans une solution de NaOH à 50 g/1, à une température de 500C, pendant 20 s,Pickling in a solution of NaOH at 50 g / l at a temperature of 50 ° C. for 20 seconds;
- Neutralisation dans une solution de HNO3 à 50 % en volume, à température ambiante et pendant 15 s, - Immersion de l'échantillon dans une solution de KF à 30 g/1 + H2SO4 à 30 g/1, à une température de 6O0C et pendant 30 s.Neutralization in 50% by volume solution of HNO3 at room temperature and for 15 seconds. Immersion of the sample in a solution of KF at 30 g / l + H 2 SO 4 at 30 g / l. temperature of 60 ° C. and for 30 s.
Traitement 6 (selon l'invention) :Treatment 6 (according to the invention):
- Dégraissage avec produit Novaclean 708 de Henkel Surface Technology pendant 30 s,- Degreasing with Novaclean 708 product from Henkel Surface Technology for 30 s,
- Décapage dans une solution de NaOH à 50 g/1, à une température de 500C pendant 20 s,Pickling in a solution of NaOH at 50 g / l at a temperature of 50 ° C. for 20 seconds;
- Neutralisation dans une solution de HNO3 à 50 % en volume, à température ambiante et pendant 15 s,Neutralization in a solution of HNO 3 at 50% by volume, at room temperature and for 15 s,
- Immersion de l'échantillon dans une solution de NH5F2 à 15 g/1 + KCl à 38 g/1 + H2SO4 à 30 g/1, à une température de 6O0C et pendant 30 s.Immersion of the sample in a solution of NH 5 F 2 at 15 g / l + KCl at 38 g / l + H 2 SO 4 at 30 g / l, at a temperature of 60 ° C. and for 30 s.
Traitement 6-bis (selon l'invention) :6-bis treatment (according to the invention):
- Même traitement que précédemment mais l'immersion finale ne dure que 15s. L'éprouvette décrite dans la figure 1 a été utilisée pour évaluer l'aptitude au brasage sans flux des matériaux ayant subi ces différents traitements. Le « V » est constitué d'une bande nue en alliage 3003, à l'état H24, et d'épaisseur 0.3 mm. Un traitement de dégraissage de 15 minutes à 250°C est appliqué au métal à braser. Aucune autre préparation de surface n'est utilisée et en particulier aucun flux n'est déposé. Le brasage est réalisé dans un four en verre à double paroi qui permet de visualiser les mouvements de brasure liquide et la formation des joints au cours du traitement. Le cycle thermique est composé d'une phase de montée en température jusqu'à 600°C selon une rampe d'environ 20°C/min, d'un maintien de 2 minutes à 600°C, et d'une descente à une vitesse d'environ 30°C/min. Le tout est réalisé sous balayage continu d'azote, avec un débit de 8 1/min.- Same treatment as before but the final immersion lasts only 15s. The test piece depicted in FIG. 1 was used to evaluate the ability to solder without flux of the materials having undergone these various treatments. The "V" consists of a bare strip of alloy 3003, in the state H24, and of thickness 0.3 mm. A degreasing treatment of 15 minutes at 250 ° C. is applied to the metal to be brazed. No other surface preparation is used and in particular no flux is deposited. Brazing is performed in a double-walled glass furnace that displays liquid solder movements and joint formation during processing. The thermal cycle consists of a temperature rise up to 600 ° C with a ramp of about 20 ° C / min, a 2 minute hold at 600 ° C, and a descent to a speed of about 30 ° C / min. The whole is carried out under continuous nitrogen sweep, with a flow rate of 8 l / min.
Les résultats sont qualifiés par une note de A à E selon l'échelle suivante :The results are qualified by a grade from A to E according to the following scale:
Les résultats obtenus sont les suivants :The results obtained are as follows:
On constate que les seuls traitements selon l'invention, comportant une acidification de Ia solution de traitement, permettent d'obtenir une bonne aptitude au brasage. It is found that the only treatments according to the invention, comprising an acidification of the treatment solution, make it possible to obtain a good solderability.

Claims

Revendications claims
1. Procédé d'assemblage par brasage sans flux de tôles, bandes ou tubes d'échangeurs thermiques, caractérisé en ce que, pour éviter l'utilisation dudit flux, lesdits tubes, bandes ou tôles, en alliage(s) d'aluminium, sont préalablement soumis à un traitement de formation, sur tout ou partie de leur surface, d'une couche de conversion à l'aide d'une solution contenant des ions K+ et F" et un ou plusieurs acide(s) en quantité telle que le pH de la solution soit inférieur à 3.1. A soldering process without flux of sheets, strips or tubes of heat exchangers, characterized in that, to avoid the use of said flow, said tubes, strips or sheets, of aluminum alloy (s), are previously subjected to a formation treatment, on all or part of their surface, of a conversion layer using a solution containing K + and F " ions and one or more acid (s) in such an amount the pH of the solution is less than 3.
2. Procédé selon la revendication 1, caractérisé en ce que ledit traitement est précédé d'un décapage alcalin.2. Method according to claim 1, characterized in that said treatment is preceded by an alkaline pickling.
3. Procédé selon l'une des revendications 1 ou 2, caractérisé en ce que l'acide est l'acide sulfurique à une concentration de 10 à 40 g/1.3. Method according to one of claims 1 or 2, characterized in that the acid is sulfuric acid at a concentration of 10 to 40 g / 1.
4. Procédé selon l'une des revendications 1 à 3, caractérisé en ce que ledit traitement se fait à une température comprise entre 30 et 100°C.4. Method according to one of claims 1 to 3, characterized in that said treatment is at a temperature between 30 and 100 ° C.
5. Procédé selon l'une des revendications 1 à 4, caractérisé en ce que les ions K+ et F' sont apportés sous forme de KF.5. Method according to one of claims 1 to 4, characterized in that the K + and F ' ions are provided in the form of KF.
6. Procédé selon l'une des revendications 1 à 4, caractérisé en ce que les ions K+ et F" sont apportés sous forme d'un mélange KCl + NH5F2. 6. Method according to one of claims 1 to 4, characterized in that the ions K + and F " are provided in the form of a mixture KCl + NH 5 F 2 .
EP05793591A 2004-07-28 2005-07-26 Method of forming a conversion layer on an aluminium alloy product prior to fluxless brazing Withdrawn EP1771601A1 (en)

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FR0408312A FR2873718B1 (en) 2004-07-28 2004-07-28 PROCESS FOR FORMING A CONVERSION LAYER ON AN ALUMINUM ALLOY PRODUCT FOR BREATHING
PCT/FR2005/001935 WO2006018535A1 (en) 2004-07-28 2005-07-26 Method of forming a conversion layer on an aluminium alloy product prior to fluxless brazing

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EP2660043B1 (en) * 2012-05-04 2021-03-03 Hydro Aluminium Rolled Products GmbH Use of an aluminium clad sheet for fluxless brazing
DE112016005165T5 (en) 2015-11-10 2018-07-19 Aleris Rolled Products Germany Gmbh Flux-free brazing process
WO2017137236A1 (en) 2016-02-09 2017-08-17 Aleris Rolled Products Germany Gmbh Aluminium multi-layered brazing sheet product and fluxless brazing method
JPWO2020204167A1 (en) * 2019-04-04 2020-10-08

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US20070204935A1 (en) 2007-09-06
FR2873718A1 (en) 2006-02-03
DE05793591T1 (en) 2007-09-06
CA2575175A1 (en) 2006-02-23
WO2006018535A1 (en) 2006-02-23
US7875129B2 (en) 2011-01-25

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