EP0756289A1 - Aluminium conductors with improved electrical contact properties and process for manufacturing the same - Google Patents

Aluminium conductors with improved electrical contact properties and process for manufacturing the same Download PDF

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Publication number
EP0756289A1
EP0756289A1 EP96420254A EP96420254A EP0756289A1 EP 0756289 A1 EP0756289 A1 EP 0756289A1 EP 96420254 A EP96420254 A EP 96420254A EP 96420254 A EP96420254 A EP 96420254A EP 0756289 A1 EP0756289 A1 EP 0756289A1
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EP
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Prior art keywords
conductor
treatment
bath
electrochemical treatment
iron
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EP96420254A
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German (de)
French (fr)
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EP0756289B1 (en
Inventor
Richard Marsolais
Gabriel Colombier
Bernard Loreau
Didier Albert
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Rio Tinto France SAS
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Aluminium Pechiney SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
    • H01B1/023—Alloys based on aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
    • C22C21/08—Alloys based on aluminium with magnesium as the next major constituent with silicon

Definitions

  • the invention relates to the field of electrical conductors in aluminum and more particularly electrical wires with a solid or wired core and the flats, and their aluminum connection devices.
  • the invention also relates to the surface treatments of these conductors.
  • the oxide layer whose electrical conductivity is low, prevents the passage of current at the place where the conductor is connected to the various devices or to the junctions of an electrical circuit.
  • the phenomenon is all the more annoying as the contact resistance can increase over time due to an evolution of the oxide layer under the effect of the passage of current, temperature or environmental conditions.
  • a commonly adopted solution consists in brushing the surfaces to be contacted and covering them with contact greases generally loaded with abrasive materials. This additional operation, most often manual and therefore expensive, hampers the development of aluminum as an electrical conductor.
  • the subject of the invention is an electrical conductor in aluminum alloy containing iron intermetallic phases, characterized in that its surface contains few particles of iron intermetallic phases with an equivalent diameter greater than 0.8 ⁇ m.
  • the electrical conductor in aluminum alloy according to the invention is characterized in that said alloy contains at least 98.5% of aluminum and between 0 and 1.5% of iron by weight, and in that less than 5% particles of intermetallic phases with iron at the surface of the conductor have an equivalent diameter greater than 0.8 ⁇ m. Preferably, less than 2% of said particles have an equivalent diameter greater than 0.8 ⁇ m.
  • the equivalent diameter corresponds to the diameter of a surface circle equivalent to the visible section of the particle.
  • the number and size of iron intermetallic phase particles can be measured by well known surface analysis techniques, such as low energy scanning electron microscopy (SEM) with atomic number contrast combined with a image analysis.
  • the particles of surface iron intermetallic phases include, as illustrated in FIG. 1, all the binary, ternary or other intermetallic particles, such as Al 3 Fe alone or in combination with Mn, Cu, Si, Ni, ..., which are not entirely immersed in the aluminum matrix or which, while being immersed in said matrix, approach within 0.2 ⁇ m of the surface of said matrix.
  • the proportion of iron by weight is between 0.05% and 1.0%.
  • An iron content of less than 0.05% leads to prohibitive manufacturing costs and generally reduces the mechanical characteristics of the conductor.
  • a proportion of iron greater than 1.0% leads to an electrical resistivity of the conductor which exceeds the tolerances normally allowed.
  • Said alloy optionally contains other elements in solid solution or precipitated in simple or intermetallic phase, such as Si, Cu, Mg, etc.
  • Said alloy is advantageously chosen from alloys of the AA1000 and AA6000 series, such as AA1110 (equivalent to AP 131050), AA1370, AA6101 and AA6201.
  • the conductor according to the invention can be obtained by spinning and / or drawing or molding according to known methods.
  • the conductors in the form of wires are preferably obtained by the CLC process (continuous casting and rolling) followed by wire drawing according to known methods.
  • the conductor can be in any metallurgical state compatible with the application.
  • the electrical resistivity of the conductor is preferably less than 3.5 ⁇ .cm, and more preferably less than 3.0 ⁇ .cm.
  • the conductor according to the invention is used in the form of a wire with a solid core, that is to say that it is formed of a single conductive strand possibly coated with an insulating sheath, or wired core, that is to say that it is formed by a set of elementary strands, generally twisted and possibly coated with an insulating sheath.
  • the conductor according to the invention is also advantageously used in electrical connection devices.
  • the conductor according to the invention is advantageously obtained by a method comprising a surface treatment according to the second object of the invention.
  • Said method optionally includes drawing operations which are carried out before and / or after the surface treatment.
  • the aluminum conductor is treated on parade or, in particular in the case of unit parts, by immersion in a succession of tanks.
  • FIG. 2a the most advantageous configuration for parade treatment is that of FIG. 2a.
  • FIG. 2b the two successive treatments are clearly separated as shown in FIG. 2b.
  • These two configurations correspond to a liquid outlet: current is transmitted by an electrode to the electrolyte which in turn transmits it to the conductor to be treated.
  • a direct current outlet which allows good control of the voltage applied to the conductor but poses problems of deterioration of the conductor.
  • Figures 3a and 3b represent two configurations in direct connection: the current is transmitted directly to the conductor to be treated by a mechanical contact.
  • the first treatment is carried out in a very alkaline medium with a pH> 8.
  • a very alkaline medium with a pH> 8.
  • Different electrolytes meeting this criterion can be used but, because of their low cost and their great chemical stability, it is particularly advantageous to use sodium hydroxide (NaOH ) or caustic potash (KOH), concentration between 10 and 100 g / l.
  • NaOH sodium hydroxide
  • KOH caustic potash
  • concentration 10 and 100 g / l.
  • the treatment is carried out at a temperature between 40 ° C and 100 ° C, under an applied voltage between 2 and 10 V. Below 2 V the running speeds are too low ( ⁇ 10 m / min). Above 10 V the treatment leaves a significant residual oxide layer (> 100 ⁇ ) and leads to excessively high contact resistances.
  • the second treatment is carried out in a weakly acidic medium (pH between 4 and 7).
  • a weakly acidic medium pH between 4 and 7
  • Different electrolytes may be suitable such as boric acid, phosphoric acid, tartaric acid.
  • This treatment is carried out at an ambient temperature which depends on the electrolyte, but which is generally between ambient and 60 ° C.
  • Tartaric acid combined with ammonia to give ammonium tartrate proves to be a particularly suitable electrolyte because it gives good results at room temperature.
  • the applied voltage is between 1V and 5V. Below 1V, the treatment gives a too thin layer and leads to poor behavior over time of the contact resistances and the corrosion resistance. Above 5V the oxide layer formed is thick and leads to high contact resistances.
  • the immersion times or the running speed and the various treatment parameters, in particular the applied voltage are adjusted.
  • detergents or emulsifiers can be added to the electrolyte, according to a known technique, intended to limit pollution of the bath, electrodes and mechanisms by greases.
  • a nitric acid neutralization tank can be added between the two electrochemical treatments which substantially improves the results obtained.
  • Figure 1 shows a schematic cross section of an aluminum conductor according to the invention.
  • the conductor is formed of a matrix (1), particles of intermetallic phases with iron (2, 3, 4), possibly particles of intermetallic phases without iron (5) and possibly elements in solid solution.
  • the particles on the surface include particles brushing on the surface (2) and particles immersed in the aluminum matrix and approaching the surface from a distance P less than 0.2 ⁇ m, such as the particle (3).
  • FIG. 2a represents the preferred configuration of the invention with a liquid current socket.
  • the conductor (10) circulates continuously in the treatment tanks (13, 14 and 15) using, in the case of a wire, an unwinder (11) and a reel (12).
  • an alternating voltage (18) induces an alternating current in the conductor (10) using the electrodes (19 and 20).
  • a direct voltage (17) induces a direct current in the conductor (10) using the electrodes (20 and 21), the conductor (10) being in anodic polarization in the tank (15).
  • Figure 2b shows another configuration with a liquid outlet.
  • a tank (16) and an electrode additional (22) have been added to separate the two treatments, while maintaining the principle of taking liquid current.
  • Figures 3a and 3b show two other configurations with direct connection to the conductor (30 and 31).
  • Figure 4 is a diagram of the contact resistance measurement method.
  • FIG. 5 is a diagram of the test loop for the thermal cycling test.
  • Six junction fittings (50) are joined together by the conductors under test (51), one of which is used as a reference (52).
  • the temperature of the reference conductor (52) is measured in the middle using a thermocouple (53).
  • Voltage drop measurement points (54) are arranged at a distance (L) on either side of the center of each junction connection (50).
  • Two voltage drop measurement points (55) separated by a distance (Lo) are also arranged on the reference conductor (52).
  • the test loop is connected to a power supply (60) which delivers either an alternating current, for thermal cycling, or a direct current for resistance measurements of the fittings and the reference conductor.
  • FIG. 6 shows the distribution of the sizes of particles of intermetallic phases with iron of a conductor of aluminum alloy AA 1370 according to the prior art (a, b) and according to the invention (c, d).
  • the ordinate gives the frequency of appearance of the particles.
  • the distributions a and c correspond to the equivalent diameter of the particles; the distributions b and d correspond to the maximum dimension.
  • FIG. 7 shows the distribution of the sizes of particles of intermetallic phases with iron of an aluminum alloy conductor AP 131050 according to the prior art (a, b) and according to the invention (c, d).
  • the ordinate gives the frequency of appearance of the particles.
  • the distributions a and c correspond to the diameter equivalent of particles; the distributions b and d correspond to the maximum dimension.
  • Examples 1 to 4 relate to conductors in the form of wires. In these examples, drivers have undergone the following tests:
  • the so-called crossed wire method was used, the principle of which is illustrated in FIG. 4.
  • Two wires were held and put under mechanical tension (T) by stirrups and then brought into contact gently .
  • a force F was applied to the contact which resulted in a deflection of the wires.
  • a current I was imposed on the circuit and the resulting voltage U was then measured.
  • the contact resistance was measured at a large number of points on the wire, namely about fifty points on three generators, i.e. 150 points in total and on three different samples.
  • the quality of the contact was expressed in terms of the mean value of the 10 best values, Rc.
  • the measurement was carried out under a force (F) of 5 newtons, for ⁇ 0.8 and 3 newtons for ⁇ 0.5, an intensity of 100 mA and a voltage in 20 mV open circuit.
  • the test loop was subjected to 200 thermal cycles by passing an overcurrent which brought the reference conductors to 120 ° C. Each cycle included a 15 minute warm up period and a 15 minute natural cool down period.
  • the evaluation of the contact resistance was carried out using the measurement of the junction resistance. For this we imposed an intensity (Io) in the loop and we measured the voltage drop (Uo) between two points each located at a distance (L) and on either side of the center of the fitting, the conductors being naked in these places.
  • the change in the junction resistance of all the fittings was given by the change in the ratio (K) between the start and the end of the test, which change was expressed as a percentage.
  • the distance (L) was 125 mm, the length (Lo) 254 mm and the intensity (Io) of 1A.
  • the wires treated according to the invention were exposed to a salt spray (5% NaCl) for 96 hours. At the end of this period, a new measurement of the contact resistance was carried out using the crossed wire method.
  • Lot A came from a spool of raw wire.
  • Lot B has undergone a surface treatment according to the invention, by scrolling in successive tanks: the AC treatment was carried out in a 60 ° C. bath containing 50 g / l of 98% pure NaOH and at a voltage of 5 V, the scrolling speed being 12 m / min ; the DC treatment was carried out in a bath containing 30 g / l of tartaric acid, the pH of which had been adjusted to 5 using ammonia, and at a voltage of 1 V.
  • Lot A came from a spool of raw wire.
  • Lot B underwent a surface treatment according to the invention, by scrolling through successive tanks, with an intermediate neutralization phase: the treatment with alternating current was carried out in a bath at 62 ° C.
  • the DC treatment was carried out in a bath containing 30 g / l of tartaric acid, the pH of which had been adjusted to 5 using ammonia, and at a voltage of 1 V; the intermediate neutralization treatment was carried out in a 69% nitric acid bath.
  • Lot A came from a coil of nickel-plated wire (obtained from the Tréfileries et Laminoirs de la M joserrateil (TLM), from the ALCATEL CABLE group).
  • Lot B came from a spool of raw, unshaven wire and was kept untreated.
  • Batches C, D and E come from a spool of wire having undergone a shaving phase during drawing. Lot C was kept without treatment.
  • Lot D underwent the anodization treatment of the prior art, in a bath containing 100 g / l of phosphoric acid, at an alternating voltage of 5 V, at a temperature of 75 ° C and at a running speed of 60 m / min.
  • Lot E underwent a surface treatment according to the invention, with an intermediate neutralization phase, by passing through successive tanks: the treatment with alternating current was carried out in a bath at 65 ° C. containing 50 g / l of NaOH 98% pure and at a voltage of 7.5 V, the running speed being 48 m / min; the DC treatment was carried out in a bath containing 30 g / l of tartaric acid, the pH of which had been adjusted to 5.5 with ammonia, and under a 1.5 V voltage; the intermediate neutralization treatment was carried out in a 69% nitric acid bath.
  • the corrosion pits observed on the wires of lot B are much less deep than those observed on the wires of lot A.

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Abstract

Aluminium alloy electrical conductors are claimed in which the aluminium alloy contains at least 98.5 wt.% Al and 0-1.5 wt.% Fe. At least 5% of the iron intermetallic phase particles at the surface of the conductor have an equivalent diameter greater than 0.8 mu m. Also claimed is the method for producing these electrical conductors and incorporates a surface treatment of aluminium wire comprising: (a) a first electrochemical treatment using an AC in an alkaline medium with a pH greater than 8; (b) a neutralising chemical treatment; and (c) a second electrochemical treatment using continuous current in a weakly acidic medium with a pH of 4-7. Further claimed are the wire produced by this method and a connecting device using this conductor.

Description

Domaine de l'inventionField of the invention

L'invention concerne le domaine des conducteurs électriques en aluminium et tout particulièrement les fils électriques à âme massive ou câblée et les méplats, et leurs dispositifs de raccordement en aluminium. L'invention concerne également les traitements de surface de ces conducteurs.The invention relates to the field of electrical conductors in aluminum and more particularly electrical wires with a solid or wired core and the flats, and their aluminum connection devices. The invention also relates to the surface treatments of these conductors.

Le mot "aluminium" s'entend au sens large de l'aluminium et ses alliages. Il en sera ainsi dans toute la suite du texte.The word "aluminum" is used in the broad sense of aluminum and its alloys. This will be the case throughout the text.

Etat de la technique et problème poséState of the art and problem posed

Le développement de l'aluminium dans les conducteurs électriques, où il est en compétition en particulier avec le cuivre, est souvent limité par ses propriétés de contact électrique. On attribue généralement aux caractéristiques mécaniques et aux propriétés de surface de l'aluminium, l'évolution des caractéristiques d'un contact électrique, telles que la résistance de contact, qui est observée dans certaines conditions avec les conducteurs en aluminium. En particulier, il est connu que les conducteurs en aluminium peuvent se déformer légèrement de manière plastique après la réalisation du contact électrique sous l'effet notamment des variations de température et des échauffements. D'autre part, il est connu que l'aluminium se recouvre naturellement d'une couche d'oxyde qui présente l'avantage de le protéger de la corrosion mais qui s'avère un inconvénient dans le cas des applications électriques. En effet la couche d'oxyde, dont la conductivité électrique est faible, s'oppose au passage du courant à l'endroit où le conducteur est raccordé aux différents appareils ou aux jonctions d'un circuit électrique. Le phénomène est d'autant plus gênant que la résistance de contact peut augmenter avec le temps à cause d'une évolution de la couche d'oxyde sous l'effet du passage du courant, de la température ou des conditions d'environnement.The development of aluminum in electrical conductors, where it competes in particular with copper, is often limited by its electrical contact properties. The mechanical characteristics and surface properties of aluminum are generally attributed to the evolution of the characteristics of an electrical contact, such as the contact resistance, which is observed under certain conditions with aluminum conductors. In particular, it is known that the aluminum conductors can deform slightly in a plastic manner after the electrical contact has been made under the effect in particular of temperature variations and overheating. On the other hand, it is known that aluminum naturally covers itself with an oxide layer which has the advantage of protecting it from corrosion but which proves to be a drawback in the case of electrical applications. Indeed, the oxide layer, whose electrical conductivity is low, prevents the passage of current at the place where the conductor is connected to the various devices or to the junctions of an electrical circuit. The phenomenon is all the more annoying as the contact resistance can increase over time due to an evolution of the oxide layer under the effect of the passage of current, temperature or environmental conditions.

On connaît plusieurs alliages d'aluminium qui offrent une bonne tenue dans le temps des propriétés de contact électrique, tels que le AA 1370, le AA 1310 ou le AA 6101. Cependant, il est bien connu que, pour certaines applications, les conducteurs en aluminium doivent subir un traitement de surface complémentaire afin de diminuer la résistance de contact et de mieux maîtriser son évolution dans le temps.Several aluminum alloys are known which offer good resistance over time to electrical contact properties, such as AA 1370, AA 1310 or AA 6101. However, it is well known that, for certain applications, the conductors in aluminum must undergo an additional surface treatment in order to reduce the contact resistance and better control its evolution over time.

Une solution communément adoptée consiste à brosser les surfaces à mettre en contact et à les recouvrir de graisses de contact généralement chargées de matières abrasives. Cette opération supplémentaire, le plus souvent manuelle et donc coûteuse, est un frein au développement de l'aluminium comme conducteur électrique.A commonly adopted solution consists in brushing the surfaces to be contacted and covering them with contact greases generally loaded with abrasive materials. This additional operation, most often manual and therefore expensive, hampers the development of aluminum as an electrical conductor.

Il a également été suggéré de déposer sur les fils conducteurs en aluminium une couche de métal de qualité électrique. Les procédés de dépôt les plus connus consistent, après une préparation de la surface, à déposer une couche d'étain ou de nickel, généralement sur sous-couche cuivre par voie chimique ou électrochimique. On peut citer par exemple le procédé décrit par le brevet est-allemand DD 150084. Le dépôt de métal a un effet bénéfique sur le plan de la résistance de contact mais présente deux inconvénients : d'une part le traitement est coûteux, d'autre part la tenue à la corrosion galvanique dans les environnements agressifs est insuffisante. Ceci explique le faible développement de ces procédés qui sont réservés à des applications très particulières comme l'aéronautique.It has also been suggested to deposit on the aluminum conductor wires a layer of metal of electrical quality. The best known deposition methods consist, after surface preparation, in depositing a layer of tin or nickel, generally on a copper sublayer by chemical or electrochemical means. We can cite for example the process described by the East German patent DD 150084. The deposition of metal has a beneficial effect in terms of contact resistance but has two drawbacks: on the one hand the treatment is expensive, on the other hand apart from the resistance to galvanic corrosion in aggressive environments is insufficient. This explains the poor development of these processes which are reserved for very specific applications such as aeronautics.

Il a également été suggéré d'effectuer une anodisation. Selon le procédé du brevet français FR 2298619, le conducteur est soumis à l'action d'un courant alternatif dans une solution aqueuse contenant de l'acide phosphorique. Ce procédé, vieux maintenant de plus de 20 ans, n'a eu aucun développement industriel, car les tests de laboratoire décrits dans ce brevet, qui faisaient état de faibles résistances de contact obtenues grâce à ce procédé, se sont avérés non représentatifs de la situation industrielle.It has also been suggested to perform anodizing. According to the method of French patent FR 2298619, the conductor is subjected to the action of an alternating current in an aqueous solution containing phosphoric acid. This process, now more than 20 years old, has had no industrial development, because the laboratory tests described in this patent, which showed the low contact resistances obtained by this process, have been found to be not representative of the industrial situation.

En effet, la demanderesse a constaté que, pour présenter un intérêt sur le plan industriel, les conducteurs en aluminium doivent, sur le plan des propriétés d'usage, présenter simultanément une résistance de contact faible et uniforme pour de faibles forces de contact, une grande stabilité dans le temps des raccordements électriques avec et sans passage de courant électrique et une tenue à la corrosion satisfaisante.Indeed, the Applicant has found that, in order to be of industrial interest, aluminum conductors must, in terms of usage properties, simultaneously present a low and uniform contact resistance for low contact forces, a high stability over time of electrical connections with and without passage of electric current and satisfactory corrosion resistance.

Ainsi, sur la base de tests représentatifs des conditions d'utilisation, la demanderesse a recherché des conducteurs en aluminium qui possèdent les propriétés d'usage recherchées et qui puissent être produits à des coûts compétitifs.Thus, on the basis of tests representative of the conditions of use, the applicant has sought aluminum conductors which have the desired use properties and which can be produced at competitive costs.

Objet de l'inventionSubject of the invention

L'invention a pour objet un conducteur électrique en alliage d'aluminium contenant des phases intermétalliques au fer caractérisé en ce que sa surface contient peu de particules de phases intermétalliques au fer de diamètre équivalent supérieur à 0,8 µm.The subject of the invention is an electrical conductor in aluminum alloy containing iron intermetallic phases, characterized in that its surface contains few particles of iron intermetallic phases with an equivalent diameter greater than 0.8 μm.

L'invention a pour deuxième objet un traitement de surface de conducteurs électriques en aluminium permettant d'obtenir les conducteurs électriques selon l'invention et caractérisé en ce qu'il comporte successivement :

  • un premier traitement électrochimique en courant alternatif dans un milieu très alcalin (pH > 8);
  • éventuellement, un traitement chimique de neutralisation ;
  • un deuxième traitement électrochimique en courant continu dans un milieu faiblement acide de pH entre 4 et 7.
The second object of the invention is a surface treatment of aluminum electrical conductors making it possible to obtain the electrical conductors according to the invention and characterized in that it successively comprises:
  • a first electrochemical treatment with alternating current in a very alkaline medium (pH>8);
  • optionally, a chemical neutralization treatment;
  • a second electrochemical treatment in direct current in a weakly acidic medium with a pH between 4 and 7.

Description de l'inventionDescription of the invention

Le conducteur électrique en alliage d'aluminium selon l'invention est caractérisé en ce que ledit alliage contient au moins 98,5 % d'aluminium et entre 0 et 1,5 % de fer en poids, et en ce que moins de 5 % des particules de phases intermétalliques au fer en surface du conducteur ont un diamètre équivalent supérieur à 0,8 µm. De préférence, moins de 2% des dites particules ont un diamètre équivalent supérieur à 0,8 µm.The electrical conductor in aluminum alloy according to the invention is characterized in that said alloy contains at least 98.5% of aluminum and between 0 and 1.5% of iron by weight, and in that less than 5% particles of intermetallic phases with iron at the surface of the conductor have an equivalent diameter greater than 0.8 µm. Preferably, less than 2% of said particles have an equivalent diameter greater than 0.8 μm.

Le diamètre équivalent correspond au diamètre d'un cercle de surface équivalente à la section visible de la particule. Le nombre et la taille des particules de phases intermétalliques au fer peuvent être mesurés par des techniques d'analyse de surface bien connues, telles que la microscopie électronique à balayage (MEB) à basse énergie avec contraste de numéro atomique combinée à un dispositif d'analyse d'image.The equivalent diameter corresponds to the diameter of a surface circle equivalent to the visible section of the particle. The number and size of iron intermetallic phase particles can be measured by well known surface analysis techniques, such as low energy scanning electron microscopy (SEM) with atomic number contrast combined with a image analysis.

Les particules de phases intermétalliques au fer en surface incluent, tel qu'illustré à la figure 1, toutes les particules intermétalliques binaires, ternaires ou autres, telles que l'Al3Fe seul ou en combinaison avec Mn, Cu, Si, Ni, ..., qui ne sont pas entièrement immergées dans la matrice aluminium ou qui, tout en étant immergées dans ladite matrice, s'approchent à moins de 0,2 µm de la surface de ladite matrice.The particles of surface iron intermetallic phases include, as illustrated in FIG. 1, all the binary, ternary or other intermetallic particles, such as Al 3 Fe alone or in combination with Mn, Cu, Si, Ni, ..., which are not entirely immersed in the aluminum matrix or which, while being immersed in said matrix, approach within 0.2 μm of the surface of said matrix.

De préférence, la proportion de fer en poids se situe entre 0,05% et 1,0%. Une proportion de fer inférieure à 0,05 % entraîne des coûts de fabrication prohibitifs et réduit généralement les caractéristiques mécaniques du conducteur. Une proportion de fer supérieure à 1,0% entraîne une résistivité électrique du conducteur qui excède les marges de tolérances normalement admises.Preferably, the proportion of iron by weight is between 0.05% and 1.0%. An iron content of less than 0.05% leads to prohibitive manufacturing costs and generally reduces the mechanical characteristics of the conductor. A proportion of iron greater than 1.0% leads to an electrical resistivity of the conductor which exceeds the tolerances normally allowed.

Ledit alliage contient éventuellement d'autres éléments en solution solide ou précipités en phase simple ou intermétallique, tels que Si, Cu, Mg, ... Ledit alliage est avantageusement choisi parmi les alliages des séries AA1000 et AA6000, tels que AA1110 (équivalent au AP 131050), AA1370, AA6101 et AA6201.Said alloy optionally contains other elements in solid solution or precipitated in simple or intermetallic phase, such as Si, Cu, Mg, etc. Said alloy is advantageously chosen from alloys of the AA1000 and AA6000 series, such as AA1110 (equivalent to AP 131050), AA1370, AA6101 and AA6201.

Le conducteur selon l'invention peut être obtenu par filage et/ou tréfilage ou moulage selon des procédés connus. Les conducteurs sous forme de fils sont obtenus de préférence par le procédé CLC (coulée et laminage en continu) suivi d'un tréfilage selon les procédés connus.The conductor according to the invention can be obtained by spinning and / or drawing or molding according to known methods. The conductors in the form of wires are preferably obtained by the CLC process (continuous casting and rolling) followed by wire drawing according to known methods.

Le conducteur peut être dans tout état métallurgique compatible avec l'application.The conductor can be in any metallurgical state compatible with the application.

La résistivité électrique du conducteur est de préférence inférieure à 3,5 µΩ.cm, et de préférence encore inférieure à 3,0 µΩ.cm.The electrical resistivity of the conductor is preferably less than 3.5 µΩ.cm, and more preferably less than 3.0 µΩ.cm.

Selon un mode de réalisation, le conducteur selon l'invention est utilisé sous forme de fil à âme massive, c'est-à-dire qu'il est formé d'un seul brin conducteur éventuellement revêtu d'une gaine isolante, ou à âme câblée, c'est-à-dire qu'il est formé d'un ensemble de brins élémentaires, généralement torsadés et éventuellement revêtus d'une gaine isolante. Le conducteur selon l'invention est aussi avantageusement utilisé dans les dispositifs de raccordement électrique.According to one embodiment, the conductor according to the invention is used in the form of a wire with a solid core, that is to say that it is formed of a single conductive strand possibly coated with an insulating sheath, or wired core, that is to say that it is formed by a set of elementary strands, generally twisted and possibly coated with an insulating sheath. The conductor according to the invention is also advantageously used in electrical connection devices.

Le conducteur selon l'invention est avantageusement obtenu par un procédé comportant un traitement de surface selon le deuxième objet de l'invention. Ledit procédé comprend éventuellement des opérations de tréfilage qui sont effectuées avant et/ou après le traitement de surface.The conductor according to the invention is advantageously obtained by a method comprising a surface treatment according to the second object of the invention. Said method optionally includes drawing operations which are carried out before and / or after the surface treatment.

Selon le traitement de surface du deuxième objet de l'invention, le conducteur en aluminium est traité au défilé ou, notamment dans le cas des pièces unitaires, par immersion dans une succession de cuves.According to the surface treatment of the second object of the invention, the aluminum conductor is treated on parade or, in particular in the case of unit parts, by immersion in a succession of tanks.

Dans le cas des fils, la configuration la plus avantageuse pour le traitement au défilé est celle de la figure 2a. Mais il est possible également d'utiliser une configuration où les deux traitements successifs sont nettement séparés comme représenté à la figure 2b. Ces deux configurations correspondent à une prise de courant liquide : le courant est transmis par une électrode à l'électrolyte qui le transmet à son tour au conducteur à traiter. On peut également utiliser une prise de courant directe qui permet de bien contrôler la tension appliquée au conducteur mais pose des problèmes de détérioration du conducteur. Les figures 3a et 3b représentent deux configurations en prise directe : le courant est transmis directement au conducteur à traiter par un contact mécanique.In the case of yarns, the most advantageous configuration for parade treatment is that of FIG. 2a. However, it is also possible to use a configuration where the two successive treatments are clearly separated as shown in FIG. 2b. These two configurations correspond to a liquid outlet: current is transmitted by an electrode to the electrolyte which in turn transmits it to the conductor to be treated. It is also possible to use a direct current outlet which allows good control of the voltage applied to the conductor but poses problems of deterioration of the conductor. Figures 3a and 3b represent two configurations in direct connection: the current is transmitted directly to the conductor to be treated by a mechanical contact.

Le premier traitement est effectué dans un milieu très alcalin de pH > 8. Différents électrolytes répondant à ce critère peuvent être utilisés mais, du fait de leur faible coût et de leur grande stabilité chimique, il est particulièrement avantageux d'utiliser la soude (NaOH) ou la potasse (KOH) caustiques, de concentration entre 10 et 100 g/l. Le traitement est effectué à une température comprise entre 40°C et 100°C, sous une tension appliquée comprise entre 2 et 10 V. En dessous de 2 V les vitesses de défilement sont trop faibles (< 10 m/min). Au-dessus de 10 V le traitement laisse une couche d'oxyde résiduelle importante (> 100 Å) et conduit à des résistances de contact trop élevées.The first treatment is carried out in a very alkaline medium with a pH> 8. Different electrolytes meeting this criterion can be used but, because of their low cost and their great chemical stability, it is particularly advantageous to use sodium hydroxide (NaOH ) or caustic potash (KOH), concentration between 10 and 100 g / l. The treatment is carried out at a temperature between 40 ° C and 100 ° C, under an applied voltage between 2 and 10 V. Below 2 V the running speeds are too low (<10 m / min). Above 10 V the treatment leaves a significant residual oxide layer (> 100 Å) and leads to excessively high contact resistances.

Le deuxième traitement est effectué dans un milieu faiblement acide (pH entre 4 et 7). Différents électrolytes peuvent convenir comme l'acide borique, l'acide phosphorique, l'acide tartrique. Ce traitement est effectué à une température ambiante qui dépend de l'électrolyte, mais qui se situe généralement entre l'ambiante et 60°C. L'acide tartrique combiné à l'ammoniaque pour donner du tartrate d'ammonium s'avère un électrolyte particulièrement approprié car il donne de bons résultats à la température ambiante. La tension appliquée est comprise entre 1V et 5V. En-dessous de 1V le traitement donne une couche trop mince et conduit à un mauvais comportement dans le temps des résistances de contact et de la tenue à la corrosion. Au-dessus de 5V la couche d'oxyde formée est épaisse et conduit à des résistances de contact élevées.The second treatment is carried out in a weakly acidic medium (pH between 4 and 7). Different electrolytes may be suitable such as boric acid, phosphoric acid, tartaric acid. This treatment is carried out at an ambient temperature which depends on the electrolyte, but which is generally between ambient and 60 ° C. Tartaric acid combined with ammonia to give ammonium tartrate proves to be a particularly suitable electrolyte because it gives good results at room temperature. The applied voltage is between 1V and 5V. Below 1V, the treatment gives a too thin layer and leads to poor behavior over time of the contact resistances and the corrosion resistance. Above 5V the oxide layer formed is thick and leads to high contact resistances.

En fonction de l'alliage et des dimensions du conducteur à traiter, on ajuste les temps d'immersion ou la vitesse de défilement et les différents paramètres des traitements, en particulier la tension appliquée.Depending on the alloy and the dimensions of the conductor to be treated, the immersion times or the running speed and the various treatment parameters, in particular the applied voltage, are adjusted.

Dans chacune des cuves de traitement, on peut ajouter à l'électrolyte, suivant une technique connue, des agents détergents ou émulsifiants destinés à limiter la pollution du bain, des électrodes et des mécanismes par les graisses.In each of the treatment tanks, detergents or emulsifiers can be added to the electrolyte, according to a known technique, intended to limit pollution of the bath, electrodes and mechanisms by greases.

Dans une variante avantageuse de l'invention, on peut ajouter entre les deux traitements électrochimiques une cuve de neutralisation à l'acide nitrique qui améliore sensiblement les résultats obtenus.In an advantageous variant of the invention, a nitric acid neutralization tank can be added between the two electrochemical treatments which substantially improves the results obtained.

Il est également avantageux de faire subir au conducteur à traiter un rasage mécanique préalable.It is also advantageous to subject the conductor to be treated to a prior mechanical shaving.

Les résultats obtenus dans les tests de résistance de contact se sont avérés nettement meilleurs pour les conducteurs de l'invention que pour les conducteurs de l'art antérieur.The results obtained in the contact resistance tests turned out to be clearly better for the conductors of the invention than for the conductors of the prior art.

FIGURESFIGURES

La figure 1 présente une coupe transversale schématique d'un conducteur en aluminium selon l'invention. Le conducteur est formé d'une matrice (1), de particules de phases intermétalliques au fer (2, 3, 4), éventuellement de particules de phases intermétalliques sans fer (5) et éventuellement d'éléments en solution solide. Les particules en surface incluent les particules effleurant à la surface (2) et les particules immergées dans la matrice aluminium et s'approchant de la surface d'une distance P inférieure à 0,2 µm, telles que la particule (3).Figure 1 shows a schematic cross section of an aluminum conductor according to the invention. The conductor is formed of a matrix (1), particles of intermetallic phases with iron (2, 3, 4), possibly particles of intermetallic phases without iron (5) and possibly elements in solid solution. The particles on the surface include particles brushing on the surface (2) and particles immersed in the aluminum matrix and approaching the surface from a distance P less than 0.2 µm, such as the particle (3).

La figure 2a représente la configuration préférée de l'invention avec prise de courant liquide. Le conducteur (10) circule en continu dans les cuves de traitement (13,14 et 15) à l'aide, dans le cas d'un fil, d'un dérouleur (11) et d'un enrouleur (12). Dans les cuves (13 et 14) une tension alternative (18) induit un courant alternatif dans le conducteur (10) à l'aide des électrodes (19 et 20). Dans la cuve (15) une tension continue (17) induit un courant continu dans le conducteur (10) à l'aide des électrodes (20 et 21), le conducteur (10) étant en polarisation anodique dans la cuve (15).FIG. 2a represents the preferred configuration of the invention with a liquid current socket. The conductor (10) circulates continuously in the treatment tanks (13, 14 and 15) using, in the case of a wire, an unwinder (11) and a reel (12). In the tanks (13 and 14) an alternating voltage (18) induces an alternating current in the conductor (10) using the electrodes (19 and 20). In the tank (15) a direct voltage (17) induces a direct current in the conductor (10) using the electrodes (20 and 21), the conductor (10) being in anodic polarization in the tank (15).

La figure 2b représente une autre configuration avec prise de courant liquide. Par rapport à la configuration de la figure la, une cuve (16) et une électrode supplémentaire (22) ont été ajoutées afin de séparer les deux traitements, tout en maintenant le principe de la prise de courant liquide.Figure 2b shows another configuration with a liquid outlet. With respect to the configuration of FIG. La, a tank (16) and an electrode additional (22) have been added to separate the two treatments, while maintaining the principle of taking liquid current.

Les figures 3a et 3b représentent deux autres configurations avec prise directe sur le conducteur (30 et 31).Figures 3a and 3b show two other configurations with direct connection to the conductor (30 and 31).

La figure 4 est un schéma de la méthode de mesure de la résistance de contact.Figure 4 is a diagram of the contact resistance measurement method.

La figure 5 est un schéma de la boucle d'essai du test de cyclage thermique. Six raccords de jonction (50) sont réunis entre eux par les conducteurs soumis à l'essai (51), dont l'un est utilisé comme référence (52). La température du conducteur de référence (52) est mesurée en son milieu à l'aide d'un thermocouple (53). Des points de mesure de la chute de tension (54) sont aménagés à une distance (L) de part et d'autre du centre de chaque raccord de jonction (50). Deux points de mesure de la chute de tension (55) séparés d'une distance (Lo), sont également aménagés sur le conducteur de référence (52). La boucle d'essai est raccordée à une alimentation électrique (60) qui délivre soit un courant alternatif, pour le cyclage thermique, soit un courant continu pour les mesures de résistance des raccords et du conducteur de référence.Figure 5 is a diagram of the test loop for the thermal cycling test. Six junction fittings (50) are joined together by the conductors under test (51), one of which is used as a reference (52). The temperature of the reference conductor (52) is measured in the middle using a thermocouple (53). Voltage drop measurement points (54) are arranged at a distance (L) on either side of the center of each junction connection (50). Two voltage drop measurement points (55) separated by a distance (Lo), are also arranged on the reference conductor (52). The test loop is connected to a power supply (60) which delivers either an alternating current, for thermal cycling, or a direct current for resistance measurements of the fittings and the reference conductor.

La figure 6 montre le distribution des tailles de particules de phases intermétalliques au fer d'un conducteur en alliage d'aluminium AA 1370 selon l'art antérieur (a,b) et selon l'invention (c,d). L'ordonnée donne la fréquence d'apparition des particules. Les distributions a et c correspondent au diamètre équivalent des particules; les distributions b et d correspondent à la dimension maximale.FIG. 6 shows the distribution of the sizes of particles of intermetallic phases with iron of a conductor of aluminum alloy AA 1370 according to the prior art (a, b) and according to the invention (c, d). The ordinate gives the frequency of appearance of the particles. The distributions a and c correspond to the equivalent diameter of the particles; the distributions b and d correspond to the maximum dimension.

La figure 7 montre le distribution des tailles de particules de phases intermétalliques au fer d'un conducteur en alliage d'aluminium AP 131050 selon l'art antérieur (a,b) et selon l'invention (c,d). L'ordonnée donne la fréquence d'apparition des particules. Les distributions a et c correspondent au diamètre équivalent des particules ; les distributions b et d correspondent à la dimension maximale.FIG. 7 shows the distribution of the sizes of particles of intermetallic phases with iron of an aluminum alloy conductor AP 131050 according to the prior art (a, b) and according to the invention (c, d). The ordinate gives the frequency of appearance of the particles. The distributions a and c correspond to the diameter equivalent of particles; the distributions b and d correspond to the maximum dimension.

EXEMPLESEXAMPLES

Les exemples 1 à 4 portent sur des conducteurs sous forme de fils. Dans ces exemples, les conducteurs ont subi les tests suivants :Examples 1 to 4 relate to conductors in the form of wires. In these examples, drivers have undergone the following tests:

Pour évaluer la résistance de contact et sa dispersion, on a utilisé la méthode dite des fils croisés, dont le principe est illustré à la figure 4. Deux fils étaient maintenus et mis sous tension mécanique (T) par des étriers puis mis en contact délicatement. Une force F était appliquée au contact ce qui entraînait une flèche des fils. Une intensité I était imposée au circuit et la tension résultante U était alors mesurée. La résistance de contact était évaluée suivant l'expression Rc = U/I. Afin d'obtenir une évaluation fiable de la qualité du contact électrique, la résistance de contact a été mesurée en un grand nombre de points sur le fil, à savoir une cinquantaine de points sur trois génératrices, c'est-à-dire 150 points au total et sur trois échantillons différents.To evaluate the contact resistance and its dispersion, the so-called crossed wire method was used, the principle of which is illustrated in FIG. 4. Two wires were held and put under mechanical tension (T) by stirrups and then brought into contact gently . A force F was applied to the contact which resulted in a deflection of the wires. A current I was imposed on the circuit and the resulting voltage U was then measured. The contact resistance was evaluated according to the expression Rc = U / I. In order to obtain a reliable evaluation of the quality of the electrical contact, the contact resistance was measured at a large number of points on the wire, namely about fifty points on three generators, i.e. 150 points in total and on three different samples.

Comme les valeurs de résistance de contact étaient dispersées et n'étaient pas distribuées selon une loi normale, la qualité du contact a été exprimée en terme de la valeur moyenne des 10 meilleures valeurs, Rc. Pour tous les cas cités dans les exemples ci-dessous, la mesure a été effectuée sous une force (F) de 5 newtons, pour ⌀ 0,8 et 3 newtons pour ⌀ 0,5, une intensité de 100 mA et une tension en circuit ouvert de 20 mV.As the contact resistance values were dispersed and were not distributed according to a normal law, the quality of the contact was expressed in terms of the mean value of the 10 best values, Rc. For all the cases cited in the examples below, the measurement was carried out under a force (F) of 5 newtons, for ⌀ 0.8 and 3 newtons for ⌀ 0.5, an intensity of 100 mA and a voltage in 20 mV open circuit.

Pour évaluer la pérennité dans le temps de la résistance de contact, on a utilisé un test de cyclage thermique par passage de courant selon une procédure dérivée de la norme NFC 63-061. Le test a consisté à former une boucle à l'aide de 6 raccords et de 7 conducteurs. Les raccords de jonction utilisés étaient des raccords en laiton à serrage sous pied de vis. Des câbles ont été formés en torsadant des brins ensemble et en les insérant dans une gaine isolante. Le nombre de brins était fonction du diamètre du fil. Un des conducteurs était utilisé comme référence en ce sens que la température de celui-ci, de même que la résistance RL d'un tronçon de longueur Lo de celui-ci, ont été considérées comme représentatives de l'ensemble des conducteurs de la boucle d'essai (figure 5). La température était mesurée à l'aide d'un thermocouple de faible diamètre (0,2 mm). La boucle d'essai était soumise à 200 cycles thermiques par passage d'une surintensité qui a porté les conducteurs de référence à 120°C. Chaque cycle comprenait une période d'échauffement de 15 minutes et une période de refroidissement naturel de 15 minutes. L'évaluation de la résistance de contact a été réalisée à l'aide de la mesure de la résistance de jonction. Pour cela on a imposé une intensité (Io) dans la boucle et on a mesuré la chute de tension (Uo) entre deux points situés chacun à une distance (L) et de part et d'autre du centre du raccord, les conducteurs étant dénudés à ces endroits. La résistance de jonction était donnée par l'expression Rj = Uo/Io. La résistance de jonction a été mesurée, pour chaque raccord, en début d'essai avant le premier cycle et en fin d'essai après le 200° cycle. La qualité du contact a été évaluée à l'aide du rapport (K) entre la moyenne des six résistances de jonction initiale (Ro) et la résistance (RL) mesurée sur le conducteur de référence (K = Ro/RL). L'évolution de la résistance de jonction de l'ensemble des raccords était donnée par l'évolution du rapport (K) entre le début et la fin de l'essai, laquelle évolution était exprimée en pourcentage. Dans ces mesures, la distance (L) était de 125 mm, la longueur (Lo) de 254 mm et l'intensité (Io) de 1A.To assess the durability over time of the contact resistance, a thermal cycling test by current flow was used according to a procedure derived from standard NFC 63-061. The test consisted of forming a loop using 6 fittings and 7 conductors. The junction fittings used were brass fittings with clamping under the screw base. Cables were formed by twisting strands together and inserting them into an insulating sheath. The number of strands was depending on the wire diameter. One of the conductors was used as a reference in the sense that the temperature thereof, as well as the resistance R L of a section of length Lo thereof, were considered to be representative of all the conductors of the test loop (Figure 5). The temperature was measured using a small diameter thermocouple (0.2 mm). The test loop was subjected to 200 thermal cycles by passing an overcurrent which brought the reference conductors to 120 ° C. Each cycle included a 15 minute warm up period and a 15 minute natural cool down period. The evaluation of the contact resistance was carried out using the measurement of the junction resistance. For this we imposed an intensity (Io) in the loop and we measured the voltage drop (Uo) between two points each located at a distance (L) and on either side of the center of the fitting, the conductors being naked in these places. The junction resistance was given by the expression Rj = Uo / Io. The junction resistance was measured, for each connection, at the start of the test before the first cycle and at the end of the test after the 200 ° cycle. The quality of the contact was evaluated using the ratio (K) between the average of the six initial junction resistances (Ro) and the resistance (R L ) measured on the reference conductor (K = Ro / R L ). The change in the junction resistance of all the fittings was given by the change in the ratio (K) between the start and the end of the test, which change was expressed as a percentage. In these measurements, the distance (L) was 125 mm, the length (Lo) 254 mm and the intensity (Io) of 1A.

Pour évaluer la tenue à la corrosion, les fils traités suivant l'invention ont été exposés à un brouillard salin (5% NaCl) pendant 96 heures. A la fin de cette période, on a procédé à une nouvelle mesure de la résistance de contact à l'aide de la méthode des fils croisés.To evaluate the corrosion resistance, the wires treated according to the invention were exposed to a salt spray (5% NaCl) for 96 hours. At the end of this period, a new measurement of the contact resistance was carried out using the crossed wire method.

Exemple 1Example 1

Les essais ont été réalisés sur du fil en aluminium AA 1370 de diamètre 0,8 mm de l'art antérieur (lot A) et selon l'invention (lot B). Le lot A provenait d'une bobine de fil brut. Le lot B a subi un traitement de surface suivant l'invention, par défilement dans des cuves successives : le traitement en courant alternatif a été effectué dans un bain à 60 °C contenant 50 g/l de NaOH pur à 98% et sous une tension de 5 V, la vitesse de défilement étant de 12 m/min ; le traitement en courant continu a été effectué dans un bain contenant 30 g/l d'acide tartrique, dont le pH avait été ajusté à 5 à l'aide d'ammoniaque, et sous une tension de 1 V.The tests were carried out on AA 1370 aluminum wire with a diameter of 0.8 mm from the prior art (lot A) and according to the invention (lot B). Lot A came from a spool of raw wire. Lot B has undergone a surface treatment according to the invention, by scrolling in successive tanks: the AC treatment was carried out in a 60 ° C. bath containing 50 g / l of 98% pure NaOH and at a voltage of 5 V, the scrolling speed being 12 m / min ; the DC treatment was carried out in a bath containing 30 g / l of tartaric acid, the pH of which had been adjusted to 5 using ammonia, and at a voltage of 1 V.

Des mesures de la distribution des tailles des particules de phases intermétalliques au fer ont été effectuées sur des échantillons issus des lots A et B. Les résultats sont regroupés dans le Tableau 1. Par convention, De désigne le diamètre équivalent et Dm la dimension maximale. Les valeurs indiquées correspondent au pourcentage des particules de diamètre De ou Dm supérieur au seuil indiqué (0,5 µm ou 0,8 µm).

Figure imgb0001
Measurements of the size distribution of the particles of intermetallic phases with iron were carried out on samples from lots A and B. The results are grouped in Table 1. By convention, De denotes the equivalent diameter and Dm the maximum dimension. The values indicated correspond to the percentage of particles with a diameter De or Dm greater than the threshold indicated (0.5 µm or 0.8 µm).
Figure imgb0001

Un échantillonnage des deux lots a été soumis aux trois tests décrits précédemment. Dans les essais de cyclage thermique, sept brins ont été utilisés pour réaliser les câbles. Les résultats sont rassemblés dans le tableau 2.

Figure imgb0002
A sample of the two lots was subjected to the three tests described above. In the thermal cycling tests, seven strands were used to make the cables. The results are collated in Table 2.
Figure imgb0002

Les résultats obtenus sur les fils suivants l'invention sont nettement meilleurs que ceux obtenus sur les fils de l'art antérieur.The results obtained on the yarns following the invention are clearly better than those obtained on the yarns of the prior art.

Exemple 2Example 2

Une deuxième série d'essais a été réalisée sur du fil aluminium AP131050 de diamètre 0,5 mm de l'art antérieur (A) et selon l'invention (B). Le lot A provenait d'une bobine de fil brut. Le lot B a subi un traitement de surface selon l'invention, par défilement dans des cuves successives, avec une phase de neutralisation intermédiaire : le traitement en courant alternatif a été effectué dans un bain à 62 °C contenant 50 g/l de NaOH pur à 98% et sous une tension de 6 V, la vitesse de défilement étant de 24 m/min ; le traitement en courant continu a été effectué dans un bain contenant 30 g/l d'acide tartrique, dont le pH avait été ajusté à 5 à l'aide d'ammoniaque, et sous une tension de 1 V ; le traitement de neutralisation intermédiaire a été effectué dans un bain d'acide nitrique à 69 %.A second series of tests was carried out on AP131050 aluminum wire with a diameter of 0.5 mm from the prior art (A) and according to the invention (B). Lot A came from a spool of raw wire. Lot B underwent a surface treatment according to the invention, by scrolling through successive tanks, with an intermediate neutralization phase: the treatment with alternating current was carried out in a bath at 62 ° C. containing 50 g / l of NaOH 98% pure and at a voltage of 6 V, the running speed being 24 m / min; the DC treatment was carried out in a bath containing 30 g / l of tartaric acid, the pH of which had been adjusted to 5 using ammonia, and at a voltage of 1 V; the intermediate neutralization treatment was carried out in a 69% nitric acid bath.

Des mesures de la distribution des tailles des particules de phases intermétalliques au fer ont été effectuées sur des échantillons issus des lots A et B. Les résultats sont regroupés au Tableau 3. La conversion est la même qu'au Tableau 1.

Figure imgb0003
Measurements of the size distribution of the particles of intermetallic phases with iron were carried out on samples from lots A and B. The results are collated in Table 3. The conversion is the same as in Table 1.
Figure imgb0003

Un échantillonnage des deux lots a été soumi aux trois tests décrits précédemment. Dans les tests de cyclage thermique, neuf brins ont été utilisés pour réaliser les câbles.A sample of the two lots was subjected to the three tests described above. In the thermal cycling tests, nine strands were used to make the cables.

Les résultats sont regroupés au Tableau 4.

Figure imgb0004
The results are collated in Table 4.
Figure imgb0004

Les résultats obtenus sur les fils suivant l'invention sont nettement meilleurs que ceux obtenus sur les fils de l'art antérieur.The results obtained on the wires according to the invention are clearly better than those obtained on the wires of the prior art.

Exemple 3Example 3

Une série d'essais a été réalisée sur cinq lots de fils en aluminium AP 131050 de diamètre 0,8 mm.A series of tests was carried out on five lots of AP 131050 aluminum wire with a diameter of 0.8 mm.

Le lot A provenait d'une bobine de fil nickelé (obtenu auprès de la Société Tréfileries et Laminoirs de la Méditerranée (TLM), du groupe ALCATEL CÂBLE). Le lot B provenait d'une bobine de fil brut, non rasé, et a été conservé sans traitement. Les lots C,D et E sont issus d'une bobine de fil ayant subi une phase de rasage en cours de tréfilage. Le lot C a été conservé sans traitement. Le lot D a subi le traitement d'anodisation de l'art antérieur, dans un bain contenant 100 g/l d'acide phosphorique, sous une tension alternative de 5 V, à une température de 75 °C et à une vitesse de défilement de 60 m/min. Le lot E a subi un traitement de surface selon l'invention, avec une phase de neutralisation intermédiaire, par défilement dans des cuves successives : le traitement en courant alternatif a été effectué dans un bain à 65 °C contenant 50 g/l de NaOH pur à 98 % et sous une tension de 7,5 V, la vitesse de défilement étant de 48 m/min ; le traitement en courant continu a été effectué dans un bain contenant 30 g/l d'acide tartrique, dont le pH avait été ajusté à 5,5 à l'aide d'ammoniaque, et sous une tension de 1,5 V ; le traitement de neutralisation intermédiaire a été effectué dans un bain d'acide nitrique à 69 %.Lot A came from a coil of nickel-plated wire (obtained from the Tréfileries et Laminoirs de la Méditerranée (TLM), from the ALCATEL CABLE group). Lot B came from a spool of raw, unshaven wire and was kept untreated. Batches C, D and E come from a spool of wire having undergone a shaving phase during drawing. Lot C was kept without treatment. Lot D underwent the anodization treatment of the prior art, in a bath containing 100 g / l of phosphoric acid, at an alternating voltage of 5 V, at a temperature of 75 ° C and at a running speed of 60 m / min. Lot E underwent a surface treatment according to the invention, with an intermediate neutralization phase, by passing through successive tanks: the treatment with alternating current was carried out in a bath at 65 ° C. containing 50 g / l of NaOH 98% pure and at a voltage of 7.5 V, the running speed being 48 m / min; the DC treatment was carried out in a bath containing 30 g / l of tartaric acid, the pH of which had been adjusted to 5.5 with ammonia, and under a 1.5 V voltage; the intermediate neutralization treatment was carried out in a 69% nitric acid bath.

Un échantillonnage des cinq lots a été soumis aux trois tests décrits précédemment. Dans les tests de cyclage thermique, sept brins ont été utilisés pour réaliser les câbles. Les résultats sont rassemblés dans le Tableau 5.

Figure imgb0005
A sample of the five lots was subjected to the three tests described above. In the thermal cycling tests, seven strands were used to make the cables. The results are collated in Table 5.
Figure imgb0005

Les fils selon l'invention donnent des résultats satisfaisants à l'ensemble des trois tests.The yarns according to the invention give satisfactory results to all three tests.

Exemple 4Example 4

Des essais de tenue à la corrosion ont été effectués sur deux lots de fils en AA6101 d'un diamètre de 0,8 mm. Le lot A correspond à des fils de l'art antérieur. Le lot B a subi un traitement selon l'invention, dans des conditions comparables à l'exemple 3.Corrosion resistance tests were carried out on two batches of AA6101 wires with a diameter of 0.8 mm. Lot A corresponds to threads of the prior art. Lot B underwent a treatment according to the invention, under conditions comparable to Example 3.

Les piqûres de corrosion observées sur les fils du lot B sont nettement moins profondes que celles observées sur les fils du lot A.The corrosion pits observed on the wires of lot B are much less deep than those observed on the wires of lot A.

Claims (17)

Conducteur électrique en alliage d'aluminium caractérisé en ce que ledit alliage contient au moins 98,5 % d'aluminium et entre 0 et 1,5 % de fer en poids, et en ce que moins de 5% des particules de phases intermétalliques au fer en surface dudit conducteur ont un diamètre équivalent supérieur à 0,8 µm.Electric conductor in aluminum alloy characterized in that said alloy contains at least 98.5% of aluminum and between 0 and 1.5% of iron by weight, and in that less than 5% of the particles of intermetallic phases at iron on the surface of said conductor have an equivalent diameter greater than 0.8 μm. Conducteur selon la revendication 1, caractérisé en ce que moins de 2% desdites particules ont un diamètre équivalent supérieur à 0,8 µm.Conductor according to claim 1, characterized in that less than 2% of said particles have an equivalent diameter greater than 0.8 µm. Conducteur selon la revendication 1 ou 2, caractérisé en ce que la proportion de fer en poids se situe entre 0,05 et 1,0%.Conductor according to claim 1 or 2, characterized in that the proportion of iron by weight is between 0.05 and 1.0%. Conducteur selon l'une des revendications 1 à 3, caractérisé en ce que ledit alliage est choisi parmi les alliages des séries AA1000 et AA6000.Conductor according to one of claims 1 to 3, characterized in that said alloy is chosen from alloys of the AA1000 and AA6000 series. Conducteur selon l'une des revendications 1 à 4, caractérisé en ce qu'il a une résistivité électrique inférieure à 3,5 µΩ.cm.Conductor according to one of claims 1 to 4, characterized in that it has an electrical resistivity less than 3.5 µΩ.cm. Procédé permettant d'obtenir le conducteur selon l'une des revendications 1 à 5, caractérisé en ce qu'il comprend un traitement de surface comportant successivement un premier traitement électrochimique en courant alternatif dans un milieu très alcalin de pH supérieur à 8 et un deuxième traitement électrochimique en courant continu dans un milieu faiblement acide de pH entre 4 et 7.Method for obtaining the conductor according to one of claims 1 to 5, characterized in that it comprises a surface treatment successively comprising a first electrochemical treatment in alternating current in a very alkaline medium of pH greater than 8 and a second electrochemical treatment in direct current in a weakly acidic medium with a pH between 4 and 7. Procédé selon la revendication 6, caractérisé en ce que ledit traitement de surface comporte, à la suite du traitement électrochimique en courant alternatif, un traitement chimique de neutralisation dans un bain contenant de l'acide nitrique.Method according to Claim 6, characterized in that the said surface treatment comprises, following the electrochemical treatment in alternating current, a chemical neutralization treatment in a bath containing nitric acid. Procédé suivant l'une des revendications 6 et 7, caractérisé en ce que le bain du traitement électrochimique en courant alternatif est constitué de soude ou de potasse caustique et ce que la teneur en soude du bain du premier traitement est comprise entre 10 g/l et 100 g/l.Process according to either of Claims 6 and 7, characterized in that the bath of the electrochemical treatment in alternating current consists of soda or caustic potash and that the soda content of the bath of the first treatment is between 10 g / l and 100 g / l. Procédé suivant l'une des revendications 6 à 8, caractérisé en ce que le traitement électrochimique en courant alternatif s'effectue sous une tension comprise entre 2 et 10V et en ce que le bain du premier traitement est maintenu à une température comprise entre 40°C et 100°C.Process according to one of Claims 6 to 8, characterized in that the electrochemical treatment in alternating current is carried out at a voltage between 2 and 10V and in that the bath of the first treatment is maintained at a temperature between 40 ° C and 100 ° C. Procédé suivant l'une des revendications 6 à 9, caractérisé en ce que le bain du traitement électrochimique en courant continu est constitué de tartrate d'ammonium.Method according to one of claims 6 to 9, characterized in that the bath of the electrochemical treatment in direct current consists of ammonium tartrate. Procédé suivant l'une des revendications 6 à 10, caractérisé en ce que le traitement électrochimique en courant continu s'effectue sous une tension entre 1 et 5V.Method according to one of claims 6 to 10, characterized in that the electrochemical treatment in direct current is carried out under a voltage between 1 and 5V. Procédé suivant l'une des revendications 6 à 11, caractérisé en ce que le conducteur à traiter subit préalablement une opération de rasage mécanique.Method according to one of Claims 6 to 11, characterized in that the conductor to be treated undergoes a mechanical shaving operation beforehand. Procédé selon la revendication 6, caractérisé en ce qu'il comprend une étape coulée et laminage en continu suivi d'un tréfilage par tout moyen connu.Method according to claim 6, characterized in that it comprises a continuous casting and rolling step followed by drawing by any known means. Procédé selon la revendication 6, caractérisé en ce qu'il comprend une étape de filage.Method according to claim 6, characterized in that it comprises a spinning step. Fil à âme massive nue ou revêtue d'une gaine isolante, caractérisé en ce qu'il comprend un conducteur selon l'une des revendications 1 à 5.Solid core wire naked or coated with an insulating sheath, characterized in that it comprises a conductor according to one of claims 1 to 5. Fil à âme câblée nue ou revêtue d'une gaine isolante, caractérisé en ce qu'il comprend des conducteurs selon l'une des revendications 1 à 5.Wire with a bare cabled core or coated with an insulating sheath, characterized in that it comprises conductors according to one of claims 1 to 5. Dispositif de raccordement caractérisé en ce qu'il comprend un conducteur selon l'une des revendications 1 à 5.Connection device characterized in that it comprises a conductor according to one of claims 1 to 5.
EP19960420254 1995-07-27 1996-07-25 Aluminium conductors with improved electrical contact properties and process for manufacturing the same Expired - Lifetime EP0756289B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9509382 1995-07-27
FR9509382A FR2737336B1 (en) 1995-07-27 1995-07-27 PROCESS FOR THE SURFACE TREATMENT OF ELECTRICAL ALUMINUM WIRES

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EP0756289A1 true EP0756289A1 (en) 1997-01-29
EP0756289B1 EP0756289B1 (en) 1999-03-24

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9859038B2 (en) 2012-08-10 2018-01-02 General Cable Technologies Corporation Surface modified overhead conductor
US10726975B2 (en) 2015-07-21 2020-07-28 General Cable Technologies Corporation Electrical accessories for power transmission systems and methods for preparing such electrical accessories
US10957468B2 (en) 2013-02-26 2021-03-23 General Cable Technologies Corporation Coated overhead conductors and methods

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2179515A1 (en) * 1972-04-11 1973-11-23 Pechiney Aluminium Aluminium-based electrical conductor - by drawing and heat treating alloy contg magnesium, silicon and iron
US3827917A (en) * 1969-06-18 1974-08-06 Kaiser Aluminium Chem Corp Aluminum electrical conductor and process for making the same
FR2298619A1 (en) * 1975-01-22 1976-08-20 Pechiney Aluminium PROCESS AND SURFACE TREATMENT OF AN ALUMINUM WIRE FOR ELECTRICAL USE
GB2099017A (en) * 1981-05-18 1982-12-01 Pirelli Brasil Aluminium alloy, and production of electrical conductors therefrom

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3827917A (en) * 1969-06-18 1974-08-06 Kaiser Aluminium Chem Corp Aluminum electrical conductor and process for making the same
FR2179515A1 (en) * 1972-04-11 1973-11-23 Pechiney Aluminium Aluminium-based electrical conductor - by drawing and heat treating alloy contg magnesium, silicon and iron
FR2298619A1 (en) * 1975-01-22 1976-08-20 Pechiney Aluminium PROCESS AND SURFACE TREATMENT OF AN ALUMINUM WIRE FOR ELECTRICAL USE
GB2099017A (en) * 1981-05-18 1982-12-01 Pirelli Brasil Aluminium alloy, and production of electrical conductors therefrom

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9859038B2 (en) 2012-08-10 2018-01-02 General Cable Technologies Corporation Surface modified overhead conductor
US10586633B2 (en) 2012-08-10 2020-03-10 General Cable Technologies Corporation Surface modified overhead conductor
US10957468B2 (en) 2013-02-26 2021-03-23 General Cable Technologies Corporation Coated overhead conductors and methods
US10726975B2 (en) 2015-07-21 2020-07-28 General Cable Technologies Corporation Electrical accessories for power transmission systems and methods for preparing such electrical accessories

Also Published As

Publication number Publication date
FR2737336A1 (en) 1997-01-31
DE69601837D1 (en) 1999-04-29
FR2737336B1 (en) 1997-09-05
DE69601837T2 (en) 1999-08-12
EP0756289B1 (en) 1999-03-24

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