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EP0125964B1 - Process and apparatus for cooling a material and application to the manufacture of refractory materials by tempering - Google Patents

Process and apparatus for cooling a material and application to the manufacture of refractory materials by tempering Download PDF

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Publication number
EP0125964B1
EP0125964B1 EP84400824A EP84400824A EP0125964B1 EP 0125964 B1 EP0125964 B1 EP 0125964B1 EP 84400824 A EP84400824 A EP 84400824A EP 84400824 A EP84400824 A EP 84400824A EP 0125964 B1 EP0125964 B1 EP 0125964B1
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EP
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Prior art keywords
nozzle
orifice
liquefied gas
treated
cooling
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.)
Expired
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EP84400824A
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German (de)
French (fr)
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EP0125964A1 (en
Inventor
Marcel Boncoeur
Bernard Hansz
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Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique CEA
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Priority to AT84400824T priority Critical patent/ATE32628T1/en
Publication of EP0125964A1 publication Critical patent/EP0125964A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D3/00—Devices using other cold materials; Devices using cold-storage bodies
    • F25D3/10—Devices using other cold materials; Devices using cold-storage bodies using liquefied gases, e.g. liquid air

Definitions

  • the subject of the present invention is a method and a device for cooling a material and more particularly the use of this method and of this device for the preparation of a material when the latter has to undergo one or more operations of time during its manufacture.
  • Cooling processes are widely used today to quench certain materials during their preparation. It is thus well known to use water or oil quenching for the preparation of metals and in particular steels.
  • water or oil quenching for the preparation of metals and in particular steels.
  • the most used method at present consists in projecting a gas jet on the liquid, that this one is contained in a crucible or that it comes from a molten electrode.
  • Such a process generally using a neutral gas avoids parasitic chemical reactions and allows, in the case of pulverulent materials, to store energy for subsequent sintering: it is thus possible to reduce the temperature and the duration of this operation.
  • Another advantage of tempering is that it makes it possible to freeze an abnormal or metastable state of the material, which may be advantageous for certain applications.
  • Document GB-A-1 413 651 describes a process of this type in which a gas is sent onto a liquid metal which flows from an orifice provided at the bottom of a crucible.
  • the object of the present invention is an improvement to current methods allowing even more efficient cooling and therefore greater speed of operation, which leads to better purity of the products treated and to a much wider range of applications.
  • the liquefied gas is usually nitrogen or argon.
  • the saturation temperature of a liquid is defined as the temperature at which the vapor contained in solution in the liquid is released: the saturation temperature is generally close to the boiling temperature, but different from it, especially in the case of liquefied gases.
  • the droplets of the liquid must be very fine and not be mixed with steam, which would have the effect of reducing the cooling capacity.
  • the fact that the liquid is in monophasic form also makes it possible to avoid jolts in the pipes and makes it easier to obtain droplets having homogeneous dimensions. Since liquefied gases are generally stored at temperatures close to their boiling point, therefore close to their saturation temperature, the operating temperature is lower than the saturation temperature without the difference exceeding 15 ° C: the expression "temperature close to the saturation temperature" used in the present text designates a temperature whose deviation from the saturation temperature does not exceed 15 ° C. This prevents vapor from being released before the liquid mixes with the carrier gas.
  • the operation is carried out at -206 ° C for a saturation temperature of approximately -196 ° C, the latter being determined experimentally.
  • the table below shows the temperatures used as a function of the pressure for nitrogen and argon.
  • the carrier gas As for the carrier gas, it has the effect not only of entraining the droplets of liquefied gas, but also of promoting heat exchanges and of lowering the surface tension of the liquid, which improves the contact with the material to be cooled.
  • the carrier gas which can be a pure gas such as helium or a mixture (helium and argon for example) will be chosen by those skilled in the art according to each particular case.
  • the "particulate" material means that the material is in divided form or in the form of particles: it can therefore s 'act either of grains if the material is solid and is in the form of powder, or drops or liquid particles if the material is in liquid form.
  • the dimensions of the first pipe are such that the coolant is in single-phase form at its entry into the nozzle.
  • This first pipe may optionally be jacketed and must have, for the coolant to be in monophasic form at its entry into the nozzle, a length less than or equal to 5 meters and a diameter of the coolant passage less than or equal at 12 mm when the pressure of the latter is between 1 and 1.5 bars.
  • the nozzle and the material to be treated are movable relative to each other.
  • the device is arranged so that the distance between the orifice of the nozzle and the material to be treated is constant throughout the duration of the relative movement of the nozzle and the material. It has been found that the best results are obtained when this distance is between 5 and 100 mm and, preferably, between 5 and 50 mm.
  • the device which is the subject of the invention, it comprises means making it possible to bring the material to be treated in front of the nozzle.
  • said means for bringing the material to be produced in front of the nozzle comprise a crucible containing this material in liquid form and allowing it to flow by gravity in front of the nozzle.
  • the means making it possible to bring the material to be produced in front of the nozzle comprise a plasma torch capable of sending a jet of molten particles of this material in front of the nozzle.
  • the means making it possible to bring the material to be produced in front of the nozzle comprise a cylindrical tank movable in rotation about its axis and consisting of two parallel flat disks connected by a side wall, the material to be produced being introduced in this reservoir in liquid form and said side wall being pierced with a number of holes to allow the liquid to exit in the form of particles by centrifugation, these particles then passing in front of the nozzle.
  • FIGS. 1 to 5 are schematic vertical sections illustrating five embodiments possible device of the invention and Figure 6 is a schematic sectional view of the nozzle used to project the coolant.
  • FIG. 1 represents a first embodiment of the device, this consisting of a sealed enclosure 1 inside which is a crucible 2 containing the material to be produced 3, for example boron in liquid form. The fusion of the latter is obtained thanks to an electrode 4 connected to an electrical circuit which makes it possible to make an arc between itself and the material 3.
  • the cooling device proper consists of a nozzle 6 having an orifice 8 for the exit of the droplets of liquefied gas, the nozzle 6 being connected on the one hand to a tank of liquefied gas 10 by a first pipe 12, and on the other hand to a tank 14 of carrier gas by a second pipe 16.
  • the liquefied gas is preferably a neutral gas such as nitrogen or argon and the carrier gas can be the same as liquefied gas, but this is not compulsory.
  • the enclosure 1 is scanned using a neutral gas, for example argon, the latter entering the enclosure by a pipe 18 connected to a reservoir 20 and leaving the enclosure by an outlet orifice 22 located at the upper part of the latter.
  • a neutral gas for example argon
  • the composition of the atmosphere prevailing inside the enclosure 1 is regularly analyzed, possibly continuously, and the scanning conditions are adjusted according to the results of the analysis.
  • the operation of the device is as follows: when the material 3 contained in the crucible 2 is melted, it is made to flow through the spout 5 of the crucible. For this, one can either tilt the crucible 2 gradually so that the flow is regular, or permanently introduce new quantities of material, the latter flowing naturally by the effect of overflow. This is how the liquid passes in front of the nozzle 6 before falling into the receptacle 24 provided at the bottom of the enclosure 1. The cooling takes place by spraying droplets of liquefied gas onto the liquid when the latter passes. in front of the orifice 8 of the nozzle 6. This has the effect of solidifying the material 3 which falls in the form of powder in the receptacle 24.
  • the droplets of liquefied gas are obtained by introducing into the nozzle 6 on the one hand the liquefied gas coming from the tank 10 through the line 12 and, on the other hand, a carrier gas coming from the tank 14 through the line 16
  • the pressure and the flow rate of the liquefied gas and of the carrier gas as well as the distance between the orifice 8 of the nozzle 6 and the material to be cooled must be carefully adjusted. It has been found that, in order to avoid troublesome phenomena in the formation of droplets, the liquefied gas coming from the reservoir 10 must be in monophasic form when it enters the nozzle 6, that is to say be found only in liquid form and not be mixed with its vapor.
  • the line 12 is advantageously a double-walled line, that is to say consisting of two concentric pipes between which a vacuum has been created in order to ensure good insulation .
  • the pressure of the liquefied gas is between 1 and 1.5 bar, so that it is in single-phase form at its entry into the nozzle 6, the length of the pipe 12 must not exceed 5 meters and that the liquid passage diameter is less than or equal to 12 millimeters.
  • the droplets of liquefied gas projected from the nozzle 6 must be spherical and have a diameter less than or equal to 40 microns.
  • the distance between the orifice 8 of the nozzle 6 and this material must be sufficiently small. In the case of liquefied gases such as argon or nitrogen, it has been determined that this distance should be between 5 and 100 millimeters and preferably between 5 and 50 millimeters.
  • FIG. 6 shows in more detail the constitution of the nozzle used in the device of the invention.
  • This consists of a body 54 on which are mounted an inlet connection 56 for the liquefied cooling gas and an inlet connection 58 for the carrier gas.
  • a head 60 on which the orifice 8 for the outlet of the coolant is located, is mounted at one end of the body 54.
  • the inlet connection 56 for the liquefied gas has an orifice 62 which places it in communication with a trigger 64 formed in the body 54 of the nozzle.
  • a conduit 66 which puts the chamber 64 in communication with a second orifice 68 which opens into a cavity 70 formed in the head 60 of the nozzle.
  • a conduit 72 which places the inlet connection 58 of the carrier gas in communication with the cavity 70.
  • this nozzle The operation of this nozzle is as follows: the liquid arriving in the inlet connector 56 passes through the first orifice 62 and arrives in the chamber 64 where it undergoes a first expansion. It then flows along the conduit 66, passes through the orifice 68 and arrives in the cavity 70 where it undergoes a second expansion.
  • the carrier gas arrives through the connector 58, circulates along the conduit 72 and opens into the cavity 70: this has the effect not only of entraining the liquefied gas in the form of droplets, but also of breaking the droplets in order to make them more small and homogeneous in size.
  • the invention also applies to the quenching of a material appearing in solid form .
  • the nozzle 6 and the material are movable relative to each other, for example the nozzle being fixed and the material to be treated moving past the orifice 8 or being driven in a rotational movement s' it is a part presenting a symmetry of revolution.
  • a confinement screen can be provided in order to thermally protect the area of the material in which the quenching is carried out.
  • Figures 2 to 5 show other embodiments of the device object of the invention in which the nozzle is fixed, but where there is provided means for bringing the material to be treated in liquid form in front of this nozzle.
  • the enclosure 1 traversed by a current of neutral gas entering through the pipe 18 and leaving through the orifice 22.
  • the electrode 26 is formed by the material which one wants to treat. The spurting of the arc between these two electrodes has the effect of melting the material at the end 27 of the electrode 26.
  • a blowing device 30 makes it possible to project a gas, preferably a neutral gas, onto the molten part 27 of the electrode 26 and thus project liquid particles of the material to be produced 3 in front of the orifice 8 of the nozzle 6, the latter being as previously connected by the pipes 12 and 16 to the tanks of liquefied gas and of carrier gas respectively .
  • the nozzle 6 is arranged above the jet of particles 3 so as to project droplets of liquefied gas onto these particles, which has the effect of cooling them sufficiently so that they solidify, and causing them to fall in the form of powder in container 24.
  • the nozzle 6 and the receptacle 24 are arranged as in Figure 2, but the liquid particles of the material to be treated 3 are obtained using a plasma torch 32 connected to a control and production of plasma not shown.
  • the operation of the device in FIG. 3 is identical to the operation of the device in FIG. 2.
  • FIG. 4 illustrates another means making it possible to bring the material to be treated in the form of liquid particles in front of the cooling nozzle.
  • the sealed enclosure 1 has the form of a cylindrical envelope 34, the lower part 36 of which has a truncated cone shape, thus constituting a receptacle for the solidified particles of the material to be treated.
  • a reservoir 38 having the shape of a cylinder bounded by two horizontal flat disks 39 and 40 connected by a side wall 42.
  • the reservoir 38 is movable in rotation around a vertical axis thanks to a motor 44 and the material to be produced can be introduced therein in liquid form via the pipe 46.
  • FIG. 5 represents a last embodiment of the device of the invention in which the material to be treated 3 is placed in solid form inside a crucible 50.
  • the device comprises a source of electrons 52, by example an electron gun, arranged so as to send an electron beam to the surface of the material contained in the crucible 5 to melt this material on the surface.
  • a blowing device which can be the same as the device 30 described with reference to FIG. 2, makes it possible to send a jet of gas to the surface of the material contained in the crucible 50 and to project liquid particles of this material in front of the orifice 8 of the nozzle 6, the latter being placed in the same manner as in the case of FIGS. 2 and 3.
  • the operation is the same as in the case of these two figures, the liquid droplets coming from the orifice 8 vanant strike the liquid particles of the material 3, which has the effect of cooling and solidifying them before they fall into the receptacle 24.
  • the method and the device which are the subject of the invention have numerous advantages since they allow quenching operations with very efficient cooling, which therefore reduces the duration of this operation and allows savings to be made over the entire material development process.
  • the fact of cooling with droplets of a liquefied neutral gas in a controlled atmosphere avoids any parasitic chemical reaction with the material to be treated, which makes it possible to obtain greater purity.
  • the process of the invention applies to the quenching of substoichiometric oxides which can be used for photography or catalysis or for the quenching of metal powders or of metallic compounds in a metastable state for obtaining actice powders for sintering.
  • the device comprising a plasma gun such as that of FIG.

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  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
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  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
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Abstract

1. Process for cooling a material (3) with the aid of a liquefied gas, characterized in that it comprises the following stages : (a) bringing the liquefied gas into a nozzle (8), said liquefied gas being at a temperature below its saturation point and whereof the variation from the latter does not exceed 15 C, (b) expanding said liquefied gas in order to obtain droplets, (c) shattering these droplets by applying thereto a carrier gas, the flow rate and pressure of the cooling liquid and the carrier gas being regulated in such a way that the droplets obtained have a diameter equal to or below 40 microns and (d) spraying the droplets obtained in stage (c) onto material (3) in order to cool the latter.

Description

La présente invention a pour objet un procédé et un dispositif pour la refroidissement d'un matériau et plus particulièrement l'utilisation de ce procédé et de ce dispositif pour l'élaboration d'un matériau lorsque celui-ci doit subir une ou plusieurs opérations de tremps au cours de sa fabrication.The subject of the present invention is a method and a device for cooling a material and more particularly the use of this method and of this device for the preparation of a material when the latter has to undergo one or more operations of time during its manufacture.

On utilise largement à l'heure actuelle des procédés de refroidissement pour effectuer la trempe de certains matériaux au cours de leur élaboration. C'est ainsi qu'il est bien connu d'utiliser la trempe à l'eau ou à l'huile pour l'élaboration des métaux et en particulier des aciers. D'autre part, dans le cas d'élaboration de matérieux réfractaires, notamment lorsque ceux- ci doivent se présanter sous forme de poudre en vue d'un frittage ultérieur, il est courant de refroidir le matériau lorsqu'il se trouve à l'état liquide. La méthode la plus employée à l'heure actuelle consiste à projeter un jet de gaz sur le liquide, que celui-ci soit contenu dans un creuset ou qu'il soit issu d'une électrode fondue. Un tel procédé utilisant généralement un gaz neutre évite des réactions chimiques parasites et permet, dans le cas de matériaux pulvérulents, d'emmagasiner de l'énergie en vue du frittage ultérieur: on peut ainsi réduire la tempéreture et le durée da cette opération. Un autre intérêt de la trempe est qu'elle permet de figer un état anormal ou métastable de la matière, ce qui peut être intéressant pour certaines applications.Cooling processes are widely used today to quench certain materials during their preparation. It is thus well known to use water or oil quenching for the preparation of metals and in particular steels. On the other hand, in the case of the production of refractory materials, in particular when these must be presented in the form of powder for subsequent sintering, it is common to cool the material when it is in the liquid state. The most used method at present consists in projecting a gas jet on the liquid, that this one is contained in a crucible or that it comes from a molten electrode. Such a process generally using a neutral gas avoids parasitic chemical reactions and allows, in the case of pulverulent materials, to store energy for subsequent sintering: it is thus possible to reduce the temperature and the duration of this operation. Another advantage of tempering is that it makes it possible to freeze an abnormal or metastable state of the material, which may be advantageous for certain applications.

Le document GB-A-1 413 651 décrit un procédé de ce type dans lequel on envoie un gaz sur un métal liquide qui s'écoule depuis un orifice prévu à la partie inférieure d'un creuset.Document GB-A-1 413 651 describes a process of this type in which a gas is sent onto a liquid metal which flows from an orifice provided at the bottom of a crucible.

Le document US-A-2 020 719 décrit un procédé de solidification dans lequel on projette des gouttelettes d'un gaz liquéfié sur des gouttelettes du matériau à refroidir: ces dernières se solidifient et on obtient le matériau sous forme de poudre.Document US-A-2,020,719 describes a solidification process in which droplets of a liquefied gas are projected onto droplets of the material to be cooled: the latter solidify and the material is obtained in the form of a powder.

La présente invention a pour objet une amélioration aux procédés actuels permettant un refroidissement encore plus efficace et donc une plus grande rapidité de l'opération, ce qui conduit à une meilleure pureté des produits traités et à une gamme d'applications beaucoup plus large.The object of the present invention is an improvement to current methods allowing even more efficient cooling and therefore greater speed of operation, which leads to better purity of the products treated and to a much wider range of applications.

Selon la principale caractéristique du procédé de refroidissement d'un matériau à l'aide d'un gaz liquéfié objet de l'invention, celui-ci comprend les étapes suivantes consistant à :

  • (a) - amener le gaz liquéfié dans une buse, ce gaz liquéfié étant à une température inférieure à sa température de saturation et dont l'écart avec cette dernière ne dépasse pas 15°C,
  • (b) - détendre ce gaz liquéfié afin d'obtenir des gouttelettes,
  • (c) - briser ces gouttelettes en envoyant sur elles un gaz porteur, le débit et la pression du liquide de refroidissement et du gaz porteur étant réglés de sorte que les gouttelettes obtenues aient un diamètre inférieur ou égal à 40 microns, et
  • (d) - projeter les gouttelettes obtenues à l'étape (c) sur le matériau afin de refroidir ce dernier.
According to the main characteristic of the process for cooling a material using a liquefied gas which is the subject of the invention, it comprises the following steps consisting in:
  • (a) - bringing the liquefied gas into a nozzle, this liquefied gas being at a temperature below its saturation temperature and whose deviation from the latter does not exceed 15 ° C,
  • (b) - expanding this liquefied gas in order to obtain droplets,
  • (c) - breaking these droplets by sending a carrier gas over them, the flow rate and the pressure of the coolant and the carrier gas being adjusted so that the droplets obtained have a diameter less than or equal to 40 microns, and
  • (d) - spraying the droplets obtained in step (c) onto the material in order to cool the latter.

Le gaz liquéfié est généralement l'azote ou l'argon. La température de saturation d'un liquide est définie comme étant la température à laquelle la vapeur contenue en solution dans le liquide se dégage: la température de saturation est généralement proche de la température d'ébullition, mais différente de celle-ci, surtout dans le cas des gaz liquéfiés.The liquefied gas is usually nitrogen or argon. The saturation temperature of a liquid is defined as the temperature at which the vapor contained in solution in the liquid is released: the saturation temperature is generally close to the boiling temperature, but different from it, especially in the case of liquefied gases.

Afin d'assurer un refroidissement efficace, il faut que les gouttelettes du liquide soient très fines et qu'elles ne soient pas mélangées à de la vapeur, ce qui aurait pour effet de diminuer la capacité de refroidissement. Le fait que le liquide soit sous forme monophasique permet en outre d'éviter les a-coups dans les canalisation et rend plus facile l'obtention de gouttelettes ayant des dimensions homogènes. Les gaz liquéfiés étant généralement stockés à des températures proches de leur température d'ébullition, donc proche de leur température de saturation, la température d'utilisation est inférieure à la température de saturation sans que l'écart dépasse 15°C : l'expression "température proche de la température de saturation" employée dans le présent texte désigne une température dont l'écart avec la température de saturation ne dépasse pas 15°C. On évite ainsi que la vapeur ne se dégage avant que le liquide se mélange au gaz porteur. Par exemple, lorsque le liquide de refroidissement est de l'azote sous un bar, on opère à -206° C pour une température de saturation de -196°C environ, cette dernière étant déterminée expérimentalement. Le tableau ci-dessous indique les températures utilisées en fonction de la pression pour l'azote et l'argon.

Figure imgb0001
In order to ensure effective cooling, the droplets of the liquid must be very fine and not be mixed with steam, which would have the effect of reducing the cooling capacity. The fact that the liquid is in monophasic form also makes it possible to avoid jolts in the pipes and makes it easier to obtain droplets having homogeneous dimensions. Since liquefied gases are generally stored at temperatures close to their boiling point, therefore close to their saturation temperature, the operating temperature is lower than the saturation temperature without the difference exceeding 15 ° C: the expression "temperature close to the saturation temperature" used in the present text designates a temperature whose deviation from the saturation temperature does not exceed 15 ° C. This prevents vapor from being released before the liquid mixes with the carrier gas. For example, when the coolant is nitrogen under a bar, the operation is carried out at -206 ° C for a saturation temperature of approximately -196 ° C, the latter being determined experimentally. The table below shows the temperatures used as a function of the pressure for nitrogen and argon.
Figure imgb0001

Quant au gaz porteur, il a pour effet non seulement d'entraîner les gouttelettes de gaz liquéfié, mais aussi de favoriser les échanges thermiques et d'abaisser la tension superficielle du liquide, ce qui améliore le contact avec le matériau à refroidir. Le gaz porteur, qui peut être un gaz pur comme l'hélium ou un mélange (hélium et argon par exemple) sera choisi par l'homme de l'art en fonction de chaque cas particulier.As for the carrier gas, it has the effect not only of entraining the droplets of liquefied gas, but also of promoting heat exchanges and of lowering the surface tension of the liquid, which improves the contact with the material to be cooled. The carrier gas, which can be a pure gas such as helium or a mixture (helium and argon for example) will be chosen by those skilled in the art according to each particular case.

D'autre part, il peut s'avérer nécessaire d'opérer sous atmosphère contrôlée et le procédé trouve une application intéressante lorsque le matériau à "particulaire" signifie que le matériau se trouve sous forme divisée ou sous forme de particules : il peut donc s'agir soit de grains si le matériau est solide et se présente sous forme de poudre, soit de gouttes ou de particules liquides si le matériau se présente sous forme liquide.On the other hand, it may prove necessary to operate under a controlled atmosphere and the process finds an interesting application when the "particulate" material means that the material is in divided form or in the form of particles: it can therefore s 'act either of grains if the material is solid and is in the form of powder, or drops or liquid particles if the material is in liquid form.

Ce dispositif comprend, de manière connue, au moins une buse reliée à au moins une source de liquide de refroidissement par une première canalisation et à au moins une source de gaz porteur par une deuxième canalisation, cette buse comportant:

  • - un orifice pour la sortie du liquide de refroidissement,
  • - un raccord d'entrée du gaz liquéfié,
  • - un premier orifice reliant le raccord d'entrée du gaz liquéfié à une chambre de détente,
  • - un conduit reliant ladite chambre de détente à un deuxième orifice,
  • - une cavité dans laquelle débouche le deuxième orifice, cette cavité étant en communication avec l'extérieur par ledit orifice de sortie du liquide de refroidissement,
  • - un raccord d'entrée du gaz porteur, et
  • - un conduit reliant le raccord d'entrée du gaz porteur à ladite cavité.
This device comprises, in known manner, at least one nozzle connected to at least one source of coolant by a first pipe and to at least one source of carrier gas by a second pipe, this nozzle comprising:
  • - an orifice for the coolant outlet,
  • - a liquefied gas inlet connection,
  • a first orifice connecting the inlet connection for the liquefied gas to an expansion chamber,
  • - a conduit connecting said expansion chamber to a second orifice,
  • a cavity into which the second orifice opens, this cavity being in communication with the outside via said orifice for the outlet of the coolant,
  • - a carrier gas inlet connection, and
  • - A conduit connecting the inlet connection of the carrier gas to said cavity.

Selon l'invention, les dimensions de la première canalisation sont telles que le liquide de refroidissement se trouve sous forme monophasique à son entrée dans la buse. Cette première canalisation peut éventuellement être à double enveloppe et doit présenter, pour que le liquide de refroidissement soit sous forme monophasique à son entrée dans la buse, une longueur inférieure ou égale à 5 mètres et un diamètre de passage du liquide de refroidissement inférieur ou égal à 12 mm lorsque la pression de ce dernier est comprise entre 1 et 1,5 bars.According to the invention, the dimensions of the first pipe are such that the coolant is in single-phase form at its entry into the nozzle. This first pipe may optionally be jacketed and must have, for the coolant to be in monophasic form at its entry into the nozzle, a length less than or equal to 5 meters and a diameter of the coolant passage less than or equal at 12 mm when the pressure of the latter is between 1 and 1.5 bars.

Généralement, la buse et le matériau à traiter sont mobiles l'un par rapport à l'autre. Dans ce cas le dispositif est agencé de telle sorte que la distance entre l'orifice de la buse et le matériau à traiter soit constante pendant toute la durée du déplacement relatif de la buse et du matériau. On a constaté qu'on obtient les meilleurs résultats lorsque cette distance est comprise entre 5 et 100 mm et, de préférence, entre 5 et 50 mm.Generally, the nozzle and the material to be treated are movable relative to each other. In this case, the device is arranged so that the distance between the orifice of the nozzle and the material to be treated is constant throughout the duration of the relative movement of the nozzle and the material. It has been found that the best results are obtained when this distance is between 5 and 100 mm and, preferably, between 5 and 50 mm.

On peut également prévoir un écran de confinement destiné à protéger thermiquement le matériau à élaborer dans la zone où l'on effectue le refroidissement et une enceinte étanche à l'intérieur de laquelle se trouvent ladite buse et le matériau à traiter lorsqu'on opère sous atmosphère contrôlée.It is also possible to provide a containment screen intended to thermally protect the material to be produced in the zone where the cooling is carried out and a sealed enclosure inside which are located said nozzle and the material to be treated when operating under controlled atmosphere.

Selon une dernière caractéristique du dispositif objet de l'invention, celui-ci comporte des moyens permettant d'amener le matériau à traiter devant la buse.According to a last characteristic of the device which is the subject of the invention, it comprises means making it possible to bring the material to be treated in front of the nozzle.

Dans un premier mode de réalisation, lesdits moyens permettant d'amener le matériau à élaborer devant la buse comprennent un creuset contenant ce matériau sous forme liquide et lui permettant de s'écouler par gravité devant la buse.In a first embodiment, said means for bringing the material to be produced in front of the nozzle comprise a crucible containing this material in liquid form and allowing it to flow by gravity in front of the nozzle.

Dans un autre mode de réalisation, ces moyens comprennent:

  • - une première électrode réalisée dans ce matériau,
  • - une deuxième électrode disposée de manière à faire jaillir un arc entre elle-même et la première électrode afin de fondre une partie du matériau constituant cette première électrode, et
  • - des moyens de soufflage pour projeter la partie fondue de la première électrode sous forme de particules liquides devant la buse.
In another embodiment, these means include:
  • - a first electrode made of this material,
  • a second electrode arranged so as to cause an arc to flow between itself and the first electrode in order to melt part of the material constituting this first electrode, and
  • - blowing means for projecting the molten part of the first electrode in the form of liquid particles in front of the nozzle.

Suivant un troisième mode de réalisation, les moyens permettant d'amener le matériau à élaborer devant la buse comprennent un chalumeau à plasma apte à envoyer un jet de particules fondues de ce matériau devant la buse.According to a third embodiment, the means making it possible to bring the material to be produced in front of the nozzle comprise a plasma torch capable of sending a jet of molten particles of this material in front of the nozzle.

Selon un autre mode de réalisation, les moyens permettant d'amener le matériau à élaborer devant la buse comprennent un réservoir cylindrique mobile en rotation autour de son axe et constitué de deux disques plans parallèles reliés par une paroi latérale, le matériau à élaborer étant introduit dans ce réservoir sous forme liquide et ladite paroi latérale étant percée d'un certain nombre de trous pour permettre la sortie du liquide sous forme de particules par centrifugation, ces particules passant ensuite devant la buse.According to another embodiment, the means making it possible to bring the material to be produced in front of the nozzle comprise a cylindrical tank movable in rotation about its axis and consisting of two parallel flat disks connected by a side wall, the material to be produced being introduced in this reservoir in liquid form and said side wall being pierced with a number of holes to allow the liquid to exit in the form of particles by centrifugation, these particles then passing in front of the nozzle.

Enfin, selon un dernier mode de réalisation du dispositif, les moyens permettant d'amener le matériau à traiter devant la buse comprennent:

  • - un creuset contenant ce matériau sous forme solide,
  • - une source d'électrons apte à envoyer un faisceau d'électrons sur le matériau contenu dans ce creuset afin de le faire fondre en surface, et
    • >- des moyens de soufflage pour projeter la partie fondue du matériau à élaborer devant la buse.
Finally, according to a last embodiment of the device, the means making it possible to bring the material to be treated in front of the nozzle include:
  • - a crucible containing this material in solid form,
  • an electron source capable of sending an electron beam onto the material contained in this crucible in order to make it melt on the surface, and
    • > - blowing means for projecting the molten part of the material to be produced in front of the nozzle.

L'invention apparaîtra mieux à la lecture de la description qui va suivre, donnée à titre d'exemple purement illustratif et nullement limitatif, en référence aux dessins annexés, dans lesquels les figures 1 à 5 sont des coupes verticales schématiques illustrant cinq modes de réalisation possibles du dispositif objet de l'invention et la figure 6 est une vue schématique en coupe de la buse utilisée pour projeter le liquide de refroidissement.The invention will appear better on reading the description which follows, given by way of purely illustrative and in no way limitative example, with reference to the appended drawings, in which FIGS. 1 to 5 are schematic vertical sections illustrating five embodiments possible device of the invention and Figure 6 is a schematic sectional view of the nozzle used to project the coolant.

La figure 1 représente un premier mode de réalisation du dispositif, celui-ci se composant d'une enceinte étanche 1 à l'intérieur de laquelle se trouve un creuset 2 contenant le matériau à élaborer 3, par exemple du bore sous forme liquide. La fusion de ce dernier est obtenue grâce à une électrode 4 reliée à un circuit électrique qui permet de faire jaillir un arc entre elle-même et le matériau 3. Le dispositif de refroidissement proprement dit se compose d'une buse 6 présentant un orifice 8 pour la sortie des gouttelettes de gaz liquéfié, la buse 6 étant reliée d'une part à un réservoir de gaz liquéfié 10 par une première canalisation 12, et d'autre part à un réservoir 14 de gaz porteur par une deuxième canalisation 16. Le gaz liquéfié est de préférence un gaz neutre comme l'azote ou l'argon et le gaz porteur peut être le même que le gaz liquéfié, mais ceci n'est pas obligatoire.FIG. 1 represents a first embodiment of the device, this consisting of a sealed enclosure 1 inside which is a crucible 2 containing the material to be produced 3, for example boron in liquid form. The fusion of the latter is obtained thanks to an electrode 4 connected to an electrical circuit which makes it possible to make an arc between itself and the material 3. The cooling device proper consists of a nozzle 6 having an orifice 8 for the exit of the droplets of liquefied gas, the nozzle 6 being connected on the one hand to a tank of liquefied gas 10 by a first pipe 12, and on the other hand to a tank 14 of carrier gas by a second pipe 16. The liquefied gas is preferably a neutral gas such as nitrogen or argon and the carrier gas can be the same as liquefied gas, but this is not compulsory.

Enfin, dans le cas où l'opération doit se dérouler sous atmosphère contrôlée, on réalise un balayage de l'enceinte 1 à l'aide d'un gaz neutre, par exemple de l'argon, ce dernier pénétrant dans l'enceinte par une canalisation 18 reliée à un réservoir 20 et sortant de l'enceinte par un orifice de sortie 22 situé à la partie supérieure de cette dernière. Le fait d'opérer sous atmosphère contrôlée évite des réactions chimiques nuisibles si le matériau à traiter est avide d'oxygène comme le bore. Pour effectuer ce contrôle, on analyse régulièrement, éventuellement en continu, la composition de l'atmosphère régnant à l'intérieur de l'enceinte 1 et on règle les conditions de balayage en fonction des résultats de l'analyse.Finally, if the operation is to take place under a controlled atmosphere, the enclosure 1 is scanned using a neutral gas, for example argon, the latter entering the enclosure by a pipe 18 connected to a reservoir 20 and leaving the enclosure by an outlet orifice 22 located at the upper part of the latter. Operating under a controlled atmosphere avoids harmful chemical reactions if the material to be treated is hungry for oxygen such as boron. To carry out this control, the composition of the atmosphere prevailing inside the enclosure 1 is regularly analyzed, possibly continuously, and the scanning conditions are adjusted according to the results of the analysis.

Le fonctionnement du dispositif est le suivant: lorsque le matériau 3 contenu dans le creuset 2 est fondu, on fait en sorte qu'il s'écoule par le bec 5 du creuset. Pour cela, on peut soit incliner le creuset 2 progressivement pour que l'écoulement soit régulier, soit introduire en permanence de nouvelles quantités de matériau, celui-ci s'écoulant naturellement par effet de trop-plein. C'est ainsi que le liquide passe devant la buse 6 avant de tomber dans le réceptacle 24 prévu à la partie inférieure de l'enceinte 1. Le refroidissement s'effectue par projection de gouttelettes de gaz liquéfié sur le liquide lorsque celui-ci passe devant l'orifice 8 de la buse 6. Ceci a pour effet de solidifier le matériau 3 qui tombe sous forme de poudre dans le réceptable 24.The operation of the device is as follows: when the material 3 contained in the crucible 2 is melted, it is made to flow through the spout 5 of the crucible. For this, one can either tilt the crucible 2 gradually so that the flow is regular, or permanently introduce new quantities of material, the latter flowing naturally by the effect of overflow. This is how the liquid passes in front of the nozzle 6 before falling into the receptacle 24 provided at the bottom of the enclosure 1. The cooling takes place by spraying droplets of liquefied gas onto the liquid when the latter passes. in front of the orifice 8 of the nozzle 6. This has the effect of solidifying the material 3 which falls in the form of powder in the receptacle 24.

L'obtention des gouttelettes de gaz liquéfié se fait en introduisant dans la buse 6 d'une part le gaz liquéfié en provenance du réservoir 10 par la canalisation 12 et, d'autre part, un gaz porteur issu du réservoir 14 par la canalisation 16. Afin que le refroidissement se fasse dans de bonnes conditions, il faut régler soigneusement la pression et le débit du gaz liquéfié et du gaz porteur ainsi que la distance entre l'orifice 8 de la buse 6 et le matériau à refroidir. On a constaté que, pour éviter des phénomènes gênants dans la formation des gouttelettes, le gaz liquéfié issu du réservoir 10 devait se trouver sous forme monophasique à son entrée dans la buse 6, c'est-à-dire se trouver uniquement sous forme liquide et ne pas être mélangé avec sa vapeur. Dans le cas d'azote ou d'argon liquide, la canalisation 12 est avantageusement une canalisation à double enveloppe,c'est-à-dire se composant de deux tuyaux concentriques entre lesquels on a fait le vide afin d'assurer une bonne isolation. Si la pression du gaz liquéfié est comprise entre 1 et 1,5 bar, pour que celui-ci se trouve sous forme monophasique à son entrée dans la buse 6, il faut que la longueur de la canalisation 12 ne dépasse pas 5 mètres et que le diamètre de passage du liquide soit inférieur ou égal à 12 millimètres. De plus, on a également constaté que, pour obtenir un refroidissement efficace, il fallait que les gouttelettes de gaz liquéfié projetées à partir de la buse 6 soient sphériques et aient un diamètre inférieur ou égal à 40 microns.The droplets of liquefied gas are obtained by introducing into the nozzle 6 on the one hand the liquefied gas coming from the tank 10 through the line 12 and, on the other hand, a carrier gas coming from the tank 14 through the line 16 In order for the cooling to take place in good conditions, the pressure and the flow rate of the liquefied gas and of the carrier gas as well as the distance between the orifice 8 of the nozzle 6 and the material to be cooled must be carefully adjusted. It has been found that, in order to avoid troublesome phenomena in the formation of droplets, the liquefied gas coming from the reservoir 10 must be in monophasic form when it enters the nozzle 6, that is to say be found only in liquid form and not be mixed with its vapor. In the case of liquid nitrogen or argon, the line 12 is advantageously a double-walled line, that is to say consisting of two concentric pipes between which a vacuum has been created in order to ensure good insulation . If the pressure of the liquefied gas is between 1 and 1.5 bar, so that it is in single-phase form at its entry into the nozzle 6, the length of the pipe 12 must not exceed 5 meters and that the liquid passage diameter is less than or equal to 12 millimeters. In addition, it has also been found that, in order to obtain effective cooling, the droplets of liquefied gas projected from the nozzle 6 must be spherical and have a diameter less than or equal to 40 microns.

Enfin, pour mieux régler la tension superficielle des gouttelettes, en particulier pour qu'elles soient sphériques et que leur diamètre reste dans les limites indiquées ci-dessus, on peut avoir intérêt à utiliser un deuxième gaz porteur dont on réglage la pression et le débit afin que la tension superficielle des gouttelettes reste dans les limites prescrites. D'autre part, pour que les gouttelettes restent suffisamment froides lors de l'impact sur le matériau à traiter, il faut que la distance entre l'orifice 8 de la buse 6 et ce matériau soit suffisamment faible. Dans le cas de gaz liquéfiés comme l'argon ou l'azote, on a pu déterminer que cette distance devait être comprise entre 5 et 100 millimètres et de préférence entre 5 et 50 millimètres.Finally, to better regulate the surface tension of the droplets, in particular so that they are spherical and that their diameter remains within the limits indicated above, it may be advantageous to use a second carrier gas whose pressure and flow are adjusted so that the surface tension of the droplets remains within the prescribed limits. On the other hand, for the droplets to remain sufficiently cold upon impact on the material to be treated, the distance between the orifice 8 of the nozzle 6 and this material must be sufficiently small. In the case of liquefied gases such as argon or nitrogen, it has been determined that this distance should be between 5 and 100 millimeters and preferably between 5 and 50 millimeters.

La figure 6 montre plus en détail la constitution de la buse utilisée dans le dispositif de l'invention. Celle-ci se compose d'un corps 54 sur lequel sont montés un raccord d'entrée 56 du gaz liquéfié de refroidissement et un raccord d'entrée 58 du gaz porteur. Une tête 60, sur laquelle se trouve l'orifice 8 de sortie du liquide de refroidissement, est montée à une extrémité du corps 54. Le raccord d'entrée 56 du gaz liquéfié comporte un orifice 62 qui le met en communication avec une chambre de détente 64 ménagée dans le corps 54 de la buse. Dans ce dernier est également ménagé un conduit 66 qui met la chambre 64 en communication avec un deuxième orifice 68 qui débouche dans une cavité 70 ménagée dans la tête 60 de la buse. Dans le corps 54 de la buse est encore prévu un conduit 72 qui met en communication le raccord d'entrée 58 du gaz porteur avec la cavité 70.Figure 6 shows in more detail the constitution of the nozzle used in the device of the invention. This consists of a body 54 on which are mounted an inlet connection 56 for the liquefied cooling gas and an inlet connection 58 for the carrier gas. A head 60, on which the orifice 8 for the outlet of the coolant is located, is mounted at one end of the body 54. The inlet connection 56 for the liquefied gas has an orifice 62 which places it in communication with a trigger 64 formed in the body 54 of the nozzle. In the latter is also provided a conduit 66 which puts the chamber 64 in communication with a second orifice 68 which opens into a cavity 70 formed in the head 60 of the nozzle. In the body 54 of the nozzle, there is also provided a conduit 72 which places the inlet connection 58 of the carrier gas in communication with the cavity 70.

Le fonctionnement de cette buse est le suivant: le liquide arrivant dans le raccord d'entrée 56 passe à travers le premier orifice 62 et arrive dans la chambre 64 où il subit une première détente. Il circule ensuite le long du conduit 66, passe à travers l'orifice 68 et arrive dans la cavité 70 où il subit une deuxième détente. Le gaz porteur arrive par le raccord 58, circule le long du conduit 72 et débouche dans la cavité 70: ceci a pour effet non seulement d'entraîner le gaz liquéfié sous forme de gouttelettes, mais encore de briser les gouttelettes afin de les rendre plus petites et de dimensions homogènes.The operation of this nozzle is as follows: the liquid arriving in the inlet connector 56 passes through the first orifice 62 and arrives in the chamber 64 where it undergoes a first expansion. It then flows along the conduit 66, passes through the orifice 68 and arrives in the cavity 70 where it undergoes a second expansion. The carrier gas arrives through the connector 58, circulates along the conduit 72 and opens into the cavity 70: this has the effect not only of entraining the liquefied gas in the form of droplets, but also of breaking the droplets in order to make them more small and homogeneous in size.

Si, dans le cas de la figure 1, on a décrit un dispositif permettant de refroidir un matériau se présentant sous forme liquide, il est bien entendu que l'invention s'applique également à la trempe d'un matériau se présentant sous forme solide. Dans ce cas, la buse 6 et le matériau sont mobiles l'un par rapport à l'autre, par exemple la buse étant fixe et le matériau à traiter défilant devant i'orifice 8 ou étant animé d'un mouvement de rotation s'il s'agit d'une pièce présentant une symétrie de révolution. Eventuellement, on peut prévoir un écran de confinement afin de protéger thermiquement la zone du matériau dans laquelle est effectuée la trempe.If, in the case of FIG. 1, a device has been described making it possible to cool a material appearing in liquid form, it is understood that the invention also applies to the quenching of a material appearing in solid form . In this case, the nozzle 6 and the material are movable relative to each other, for example the nozzle being fixed and the material to be treated moving past the orifice 8 or being driven in a rotational movement s' it is a part presenting a symmetry of revolution. Optionally, a confinement screen can be provided in order to thermally protect the area of the material in which the quenching is carried out.

Les figures 2 à 5 représentent d'autres modes de réalisation du dispositif objet de l'invention dans lesquels la buse est fixe, mais où l'on a prévu des moyens pour amener le matériau à traiter sous forme liquide devant cette buse. Par exemple, dans le cas de la figure 2, on retrouve l'enceinte 1 parcourue par un courant de gaz neutre entrant par la conduite 18 et sortant par l'orifice 22. A l'intérieur de l'enceinte 1 se trouvent deux électrodes 26 et 28 entre lesquelles on fait jaillir un arc, mais l'électrode 26 est constituée par le matériau qu'on veut traiter. Le jaillissement de l'arc entre ces deux électrodes a pour effet de faire fondre le matériau à l'extrémité 27 de l'électrode 26. Un dispositif de soufflage 30 permet de projeter un gaz, de préférence un gaz neutre, sur la partie fondue 27 de l'électrode 26 et de projeter ainsi des particules liquides du matériau à élaborer 3 devant l'orifice 8 de la buse 6, cette dernière étant comme précédemment reliée par les canalisations 12 et 16 aux réservoirs de gaz liquéfié et de gaz porteur respectivement. La buse 6 est disposée au-dessus du jet de particules 3 de manière à projeter des gouttelettes de gaz liquéfié sur ces particules, ce qui a pour effet de les refroidir suffisamment pour qu'elles se solidifient, et de les faire tomber sous forme de poudre dans le réceptable 24.Figures 2 to 5 show other embodiments of the device object of the invention in which the nozzle is fixed, but where there is provided means for bringing the material to be treated in liquid form in front of this nozzle. For example, in the case of FIG. 2, we find the enclosure 1 traversed by a current of neutral gas entering through the pipe 18 and leaving through the orifice 22. Inside the enclosure 1 are two electrodes 26 and 28 between which an arc is spouted, but the electrode 26 is formed by the material which one wants to treat. The spurting of the arc between these two electrodes has the effect of melting the material at the end 27 of the electrode 26. A blowing device 30 makes it possible to project a gas, preferably a neutral gas, onto the molten part 27 of the electrode 26 and thus project liquid particles of the material to be produced 3 in front of the orifice 8 of the nozzle 6, the latter being as previously connected by the pipes 12 and 16 to the tanks of liquefied gas and of carrier gas respectively . The nozzle 6 is arranged above the jet of particles 3 so as to project droplets of liquefied gas onto these particles, which has the effect of cooling them sufficiently so that they solidify, and causing them to fall in the form of powder in container 24.

Dans le cas de la figure 3, la buse 6 et le réceptacle 24 sont disposés comme dans la figure 2, mais les particules liquides du matériau à traiter 3 sont obtenues à l'aide d'un chalumeau à plasma 32 relié à un système de contrôle et de production de plasma non représenté. Le fonctionnement du dispositif de la figure 3 est identique au fonctionnement du dispositif de la figure 2.In the case of Figure 3, the nozzle 6 and the receptacle 24 are arranged as in Figure 2, but the liquid particles of the material to be treated 3 are obtained using a plasma torch 32 connected to a control and production of plasma not shown. The operation of the device in FIG. 3 is identical to the operation of the device in FIG. 2.

La figure 4 illustre un autre moyen permettant d'amener le matériau à traiter sous forme de particules liquides devant la buse de refroidissement. Dans ce mode de réalisation, l'enceinte étanche 1 a la forme d'une enveloppe cylindrique 34 dont la partie inférieure 36 a une forme en tronc de cône, constituant ainsi un réceptacle pour les particules solidifiées du matériau à traiter. A la partie supérieure du récipient 34 se trouve un réservoir 38 ayant la forme d'un cylindre limité par deux disques plans horizontaux 39 et 40 reliés par une paroi latérale 42. Le réservoir 38 est mobile en rotation autour d'un axe vertical grâce à un moteur 44 et on peut y introduire le matériau à élaborer sous forme liquide par la canalisation 46. Ce dernier arrive donc dans le réservoir 38 et, comme la paroi latérale 42 de ce dernier est percée de trous de faible diamètre 48, le liquide s'échappe par ces orifices sous l'effet de la force centrifuge. Du fait que le diamètre de ces orifices est très faible, ce sont des particules liquides qui s'echappent.FIG. 4 illustrates another means making it possible to bring the material to be treated in the form of liquid particles in front of the cooling nozzle. In this embodiment, the sealed enclosure 1 has the form of a cylindrical envelope 34, the lower part 36 of which has a truncated cone shape, thus constituting a receptacle for the solidified particles of the material to be treated. At the upper part of the container 34 is a reservoir 38 having the shape of a cylinder bounded by two horizontal flat disks 39 and 40 connected by a side wall 42. The reservoir 38 is movable in rotation around a vertical axis thanks to a motor 44 and the material to be produced can be introduced therein in liquid form via the pipe 46. The latter therefore arrives in the reservoir 38 and, as the side wall 42 of the latter is pierced with small diameter holes 48, the liquid s 'escapes through these orifices under the effect of centrifugal force. Because the diameter of these orifices is very small, it is liquid particles which escape.

On voit sur la figure qu'on disposé un certain nombre de buses de refroidissement identiques aux buses décrites en référence aux figures précédentes tout autour du récipient 34: seules les deux buses 6a et 6b sont visibles sur le dessin. Les gouttelettes de gaz liquéfié projetées par ces dernières frappent les particules liquides à leur sortie du réservoir 38 et ce sont donc des particules solides qu'on recueille à la partie inférieure 36 de l'enveloppe 34.It can be seen in the figure that a number of cooling nozzles identical to the nozzles described with reference to the preceding figures are arranged all around the container 34: only the two nozzles 6a and 6b are visible in the drawing. The droplets of liquefied gas projected by the latter strike the liquid particles at their outlet from the reservoir 38 and these are therefore solid particles which are collected at the lower part 36 of the envelope 34.

Enfin, la figure 5 représente un dernier mode de réalisation du dispositif de l'invention dans lequel le matériau à traiter 3 est placé sous forme solide à l'intérieur d'un creuset 50. Le dispositif comporte une source d'électrons 52, par exemple un canon à électrons, disposée de manière à envoyer un faisceau d'électrons à la surface du matériau contenu dans le creuset 5 pour faire fondre ce matériau en surface. Un dispositif de soufflage, qui peut être le même que le dispositif 30 décrit en référence à la figure 2, permet d'envoyer un jet de gaz à la surface du matériau contenue dans le creuset 50 et der projeter des particules liquides de cce matériau devant l'orifice 8 de la buse 6, cette dernière étant placée de la même manière que dans le cas des figures 2 et 3. Le fonctionnement est le même que dans le cas de ces deux figures, les gouttelettes liquides issues de l'orifice 8 vanant frapper les particules liquides du matériau 3, ce qui a pour effet de les refroidir et de les solidifer avant qu'elles ne tombent dans le réceptacle 24.Finally, FIG. 5 represents a last embodiment of the device of the invention in which the material to be treated 3 is placed in solid form inside a crucible 50. The device comprises a source of electrons 52, by example an electron gun, arranged so as to send an electron beam to the surface of the material contained in the crucible 5 to melt this material on the surface. A blowing device, which can be the same as the device 30 described with reference to FIG. 2, makes it possible to send a jet of gas to the surface of the material contained in the crucible 50 and to project liquid particles of this material in front of the orifice 8 of the nozzle 6, the latter being placed in the same manner as in the case of FIGS. 2 and 3. The operation is the same as in the case of these two figures, the liquid droplets coming from the orifice 8 vanant strike the liquid particles of the material 3, which has the effect of cooling and solidifying them before they fall into the receptacle 24.

Ainsi, le procédé et le dispositif objets de l'invention présentent de nombreux avantages puisqu'ils permettent des opérations de trempe avec un refroidissement très efficace, ce qui diminue donc la durée de cette opération et permet de réaliser des économies sur l'ensemble du procédé d'élaboration du matériau. D'autre part, le fait d'opérer le refroidissement avec des gouttelettes d'un gaz neutre liquéfié dans une atmosphère contrôlée évite toute réaction chimique parasite avec le matériau à traiter, ce qui permet d'obtenir une plus grande pureté.Thus, the method and the device which are the subject of the invention have numerous advantages since they allow quenching operations with very efficient cooling, which therefore reduces the duration of this operation and allows savings to be made over the entire material development process. On the other hand, the fact of cooling with droplets of a liquefied neutral gas in a controlled atmosphere avoids any parasitic chemical reaction with the material to be treated, which makes it possible to obtain greater purity.

Quant au domaine d'application, il est extrêmement vaste et couvre presque tous les procédes d'élaboration dans lesquels un matériau doit être soumis à un traitement de trempe. C'est ainsi que le procédé de l'invention s'applique à la trempe d'oxydes sous- stoechiométriques utilisables pour la photographie ou la catalyse ou pour la trempe de poudres de métaux ou de composés métalliques dans un état métastable pour l'obtention de poudres actices en vue du frittage. Par exemple, avec le dispositif comportant un pistolet à plasma tel que celui de la figure 3, on a pu figer du bore sous sa forme amorphe et obtenir de l'oxyde de lutétium sous-stoechiométrique: alors que la forme stable de ce composé correspond à un produit de couleur blanche et de formule chimique LU203, on a pu obtenir l'oxyde métastable bleu dont la formule chimique s'écrit Lu20x, x étant un nombre variable mais voisin de 2,8. Le procédé objet de l'invention s'applique encore à la trempe de lingots après cuisson ou pressage ou pour fragiliser des matériaux avant leur destruction par broyage. Il peut encore avantageusement être utilisé pour le refroidissement de dépôts plasma ou pour l'élaboration de matériaux supra-conducteurs, de verres métalliques ou pour la trempe du verre.As for the field of application, it is extremely wide and covers almost all the production procedures in which a material must be subjected to a quenching treatment. Thus, the process of the invention applies to the quenching of substoichiometric oxides which can be used for photography or catalysis or for the quenching of metal powders or of metallic compounds in a metastable state for obtaining actice powders for sintering. For example, with the device comprising a plasma gun such as that of FIG. 3, it has been possible to freeze boron in its amorphous form and to obtain substoichiometric lutetium oxide: while the stable form of this compound corresponds to a product of white color and chemical formula L U2 0 3 , it was possible to obtain the blue metastable oxide whose chemical formula is written Lu 2 0 x , x being a variable number but close to 2.8. The process which is the subject of the invention also applies to the quenching of ingots after baking or pressing or for weakening materials before their destruction by grinding. It can also advantageously be used for cooling plasma deposits or for the preparation of superconductive materials, metallic glasses or for tempering glass.

Claims (20)

1. Process for cooling a material (3) with the aid of a liquefied gas, characterized in that it comprises the following stages:
(a) bringing the liquefied gas into a nozzle (8), said liquefied gas being at a temperature below its saturation point and whereof the variation from the latter does not exceed 15°C,
(b) expanding said liquefied gas in order to obtain droplets,
(c) shattering these droplets by applying thereto a carrier gas, the flow rate and pressure of the cooling liquid and the carrier gas being regulated in such a way that the droplets obtained have a diameter equal to or below 40 microns and
(d) spraying the droplets obtained in stage (c) onto material (3) in order to cool the latter.
2. Process according to claim 1, characterized in that said liquefied gas is chosen in the group including nitrogen and argon.
3. Process according to any one of the claims 1 and 2, characterized in that working takes place under a controlled atmosphere.
4. Process according to any one of the claims 1 to 3, characterized in that the material to be treated (3) is prepared in a particular form before subjecting it to the action of the cooling liquid.
5. Process for producing a refractory material of the type involving at least one stage in which the material to be produced is subject to a tempering treatment, characterized in that said tempering is performed by the cooling process according to any one of the claims 1 to 4.
6. Apparatus for performing the process according to any one of the claims 1 to 4 comprising at least one nozzle (6) connected to at least one cooling liquid source (10) by a first pipe (12) and to at least one carrier gas source (14) by a second pipe (16), said nozzle (6) having:
- an orifice (8) for the discharge of the cooling liquid,
- an intake connection (56) for the liquefied gas,
- a first orifice (62) connecting the intake connection (56) for the liquefied gas to an expansion chamber (64),
- a duct (66) connecting the expansion chamber (64) to a second orifice (68),
- a cavity (70) into which issues the second orifice (68), said cavity (70) being linked with the outside by the cooling liquid discharge orifice (8),
- an intake connection (58) for the carrier gas and
- a duct (72) linking the intake connection (58) for the carrier gas to said cavity (70),
characterized in that the dimensions of the first pipe (12) are such that the cooling liquid is in monophase form when it enters nozzle (6).
7. Apparatus according to claim 6, characterized in that the first pipe (12) has a double envelope.
8. Apparatus according to any one of the claims 6 and 7, characterized in that said first pipe (12) has a length equal to or less than 5 metres and a cooling liquid passage diameter equal to or less than 12 mm when the pressure of the latter is between 1 and 1.5 bar.
9. Apparatus according to any one of the claims 6 to 8, characterized in that nozzle (6) and the material (3) to be treated are mobile with respect to one another.
10. Apparatus according to claim 9, characterized in that it is arranged in such a way that the distance between the orifice (8) of nozzle (6) and the material (3) to be treated is constant throughout the duration of the relative displacement of nozzle (6) and material (3).
11. Apparatus according to claim 10, characterized in that the distance between orifice (8) of nozzle (6) and the material to be treated is between 5 and 100 mm.
12. Apparatus according to claim 11, characterized in that the distance between orifice (8) of nozzle (6) and the material to be treated is between 5 and 50 mm.
13. Apparatus according to any one of the claims 6 to 12, characterized in that it also has a confinement shield for thermally protecting the material to be produced in the area where cooling takes place.
14. Apparatus according to any one of the claims 6 to 13, characterized in that it also comprises a tight enclosure (1) within which is located a nozzle (6) and the material (3) to be treated.
15. Apparatus according to any one of the claims 6 to 14, characterized in that it has means making it possible to bring the material (3) to be treated in front of nozzle (6).
16. Apparatus according to claim 15, characterized in that the means making it possible to bring the material (3) to be produced in front of nozzle (6) comprise a crucible (2) containing said material in liquid form and enabling it to flow by gravity in front of nozzle (6).
17. Apparatus according to claim 15, characterized in that the means making it possible to bring the material to be produced in front of nozzle (6) comprise:
- a first electrode (26) made from said material,
- a second electrode (28) arranged in such a way as to strike an arc between itself and the first electrode (26) in order to melt part (27) of the material constituting said first electrode (26) and
- blowing means (30) for spraying the melted part (27) of the first electrode (26) in the form of liquid particles in front of nozzle (6).
18. Apparatus according to claim 15, characterized in that the means making it possible to bring the material to be produced in front of nozzle (6) comprise a plasma torch (32) able to pass a jet of melted particles of this material in front of nozzle (6).
19. Apparatus according to claim 15, characterized in that the means making it possible to bring the material to be produced in front of nozzle (6) comprise a cylindrical tank (38) mobile in rotation about its axis and formed from two parallel, planar disks (39, 40) connected by a side wall (42), the material to be produced being introduced into said tank in liquid form and said side wall (42) having a certain number of holes (48) to permit the discharge of the liquid in the form of particles by centrifuging, said particles then passing in front of nozzle (6).
20. Apparatus according to claim 15, characterized in that the means making it possible to bring the material to be treated in front of nozzle (6) comprise:
- a crucible (50) containing said material in solid form,
- an electron source (52) able to pass an electron beam onto the material (3) contained in crucible (50) in order to surface melt the same and
- blowing means (30) for spraying the melted part of the material to be produced in front of nozzle (6).
EP84400824A 1983-04-29 1984-04-24 Process and apparatus for cooling a material and application to the manufacture of refractory materials by tempering Expired EP0125964B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT84400824T ATE32628T1 (en) 1983-04-29 1984-04-24 METHOD AND DEVICE FOR COOLING A MATERIAL AND USE FOR THE MANUFACTURE OF REFRACTORY MATERIALS BY HARDENING.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8307164A FR2545202B1 (en) 1983-04-29 1983-04-29 METHOD AND DEVICE FOR COOLING A MATERIAL AND APPLICATION TO THE PREPARATION OF REFRACTORY MATERIALS BY TEMPERING
FR8307164 1983-04-29

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EP0125964A1 EP0125964A1 (en) 1984-11-21
EP0125964B1 true EP0125964B1 (en) 1988-02-24

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AT (1) ATE32628T1 (en)
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IE921308A1 (en) * 1992-04-23 1993-11-03 Schwan Ltd A method and apparatus for reducing the temperature of a¹flue gas stream
FR2766738B1 (en) * 1997-08-01 1999-09-03 Air Liquide METHOD AND DEVICE FOR SEQUENTIALLY SPRAYING A CRYOGENIC LIQUID, METHOD AND INSTALLATION FOR COOLING THEREOF

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Publication number Priority date Publication date Assignee Title
US1475340A (en) * 1922-10-21 1923-11-27 James D Davis Atomizer
DE460898C (en) * 1924-10-21 1928-06-07 Hartstoff Metall Akt Ges Hamet Manufacture of fine grains from molten metal
US2020719A (en) * 1934-06-12 1935-11-12 Girdler Corp Process and apparatus for solidifying material in finely subdivided form
US2460992A (en) * 1946-02-06 1949-02-08 Federal Mogul Corp Method of atomizing metal
GB713009A (en) * 1951-08-21 1954-08-04 Glacier Co Ltd Improvements in or relating to the manufacture of metallic powders
US3041672A (en) * 1958-09-22 1962-07-03 Union Carbide Corp Making spheroidal powder
US3111011A (en) * 1960-07-01 1963-11-19 Bar Rup Corp Apparatus for preserving liquids by freezing
FR1395562A (en) * 1963-08-14 1965-04-16 Reynolds Metals Co Preparation and rolling of aluminous particles
FR2098951A5 (en) * 1970-07-31 1972-03-10 Anvar Spheroidal granules of refractory material prodn - by two-stage pulverization of molten raw material
GB1413651A (en) * 1971-11-04 1975-11-12 Singer A R E Atomising of metals
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SE7704410L (en) * 1976-04-23 1977-10-24 Bp Chem Int Ltd TREATMENT OF LATICES
CH645455A5 (en) * 1979-02-20 1984-09-28 Linde Ag SPRAYING SYSTEM FOR DELIVERING A CRYOGENIC REFRIGERANT.
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Also Published As

Publication number Publication date
FR2545202B1 (en) 1989-04-07
DE3469456D1 (en) 1988-03-31
EP0125964A1 (en) 1984-11-21
FR2545202A1 (en) 1984-11-02
ATE32628T1 (en) 1988-03-15

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