Device for stabilising molten samples and system for producing and stabilising molten samples

Abstract

The invention relates to a device for stabilising molten samples in a levitator, referred to as the device, the device comprising: - a hollow tube made of refractory material, referred to as the refractory tube, forming a guide inside which a wire made of a metal or of a metal alloy is intended to be arranged; - a mechanism for unwinding / winding the wire, which device is located upstream of the refractory tube with respect to a direction connecting the unwinding / winding mechanism to the refractory tube and is arranged to move the wire in translation through the refractory tube; - an acoustic levitation device, referred to as the levitator, comprising an opening or passage that connects the inside of the levitator with the outside and through which the wire and / or the hollow tube made of refractory material extends; - a control system arranged and / or programmed to control the winding / unwinding of the wire so as to control the position of a distal end of the wire outside the refractory tube and / or position the distal end of the wire at the centre of the levitator.

Description

[0001] DESCRIPTION

[0002] Molten sample stabilization device and molten sample production and stabilization system

[0003] Technical field

[0004] The present invention relates, in particular, to the characterization of molten metals at high temperatures, typically temperatures above 800°C. In practice, the treatment of the liquid metal allows the adjustment of the chemical composition of the alloy as well as the elimination of inclusion defects, immiscible elements in the alloy which degrade its usage properties.

[0005] Mastering industrial tools for the development of new generations of alloys requires a perfect knowledge of thermophysical properties at very high temperatures, as well as an understanding of the mechanisms of genesis of inclusion defects. Furthermore, knowledge of the thermophysical properties of liquid metal is particularly critical in additive metallurgy, whether for developing powders or at the heart of the 3D printing process.

[0006] It is necessary to study liquid metal in detail at very high temperatures to precisely characterize certain thermophysical properties, for example viscosity or surface tension, or even the reactive phenomena at the origin of inclusions. Such an approach poses great difficulties on the experimental level.

[0007] State of the prior art

[0008] The use of a crucible in which the metal to be analyzed is brought to a liquid state is known in the state of the art. Beyond the difficult-to-access operating conditions, which can be from 1500 to 2000 °C, the alloys are very reactive and there is no crucible that can guarantee the absence of pollution of the sample in the liquid state by the crucible.

[0009] Also known in the prior art is the use of levitating the alloy in order to eliminate any potential chemical pollution from a crucible. However, prior art levitators used for the study of molten samples require levitating a solid sample and then melting the levitated solid sample. This leads to a set of disadvantages related, among other things, to the change in state of the initially levitated sample.

[0010] Among these levitation techniques, induction levitation-melting is known: it is generated by a vertical coil. The strong coupling between levitation and heating imposes a reduced heating temperature range. In addition, the induced forces generate internal flows that are detrimental to the study of molten metals. This technique is only applicable to metals. Finally, this technique requires adapting the coil to each type of material and each geometry of the sample studied.

[0011] Aerodynamic levitation is also known. This technique involves lifting the material by a jet of gas under the sample. Heating is provided independently by a laser. The technique is well suited to the intended objectives, but it does have drawbacks. The sample is partially hidden by the nozzle expelling the gas, and the flow of gas around the sample generates a flow on the surface of the sample.

[0012] Electrostatic levitation is also particularly suitable for studying liquid metal. However, this technique is difficult to implement. Furthermore, it is limited to metals and difficult to adapt to poorly conductive materials.

[0013] Acoustic levitation is also known in the state of the art.

[0014] Currently, no acoustic levitation device can maintain the levitation of high-density metals in a liquid state at temperatures above 700°C. The main obstacle is linked to the use of a single high-power source coupled with a reflector.

[0015] The speed of waves in gas varies greatly with temperature. Hot gas flows around the sample cause aerodynamic turbulence on the levitating sample. These disturbances eventually cause a destabilization of the levitation of the molten sample after a few tens of seconds. In addition, acoustic levitation devices cause the molten sample to rotate on itself. When the sample passes into the liquid state, a liquid layer appears on a solid core. This liquid layer is partially ejected from the solid core, causing material ejections. This phenomenon also contributes to the destabilization of the molten sample, then to the loss of levitation, via an action-reaction phenomenon during material ejections from the molten sample.

[0016] An object of the invention is, furthermore, to provide a sample stabilization device for the production of molten samples in a levitator and a system for stabilizing and producing molten samples:

[0017] - allowing the handling of any type of metal alloy, and / or

[0018] - allowing the molten object to be stabilized during levitation, and / or

[0019] - allowing an object to be manipulated with micrometric precision, and / or

[0020] - allowing a sample to be studied over a wide temperature range and up to temperatures of 2500°C, and / or

[0021] - allowing the study of any type of sample, whatever its density, and / or

[0022] - not requiring complex electronic control means or feedback loop, and / or

[0023] - easy to use, and / or

[0024] - inexpensive and easy to implement,

[0025] - to control and manage the size of the liquid sample being melted,

[0026] - to prevent ejections of material from the molten sample into a levitator.

[0027] Presentation of the invention

[0028] For this purpose, a device is proposed for stabilizing molten samples, preferably intended to be melted, more preferably intended to be melted in a levitator, said device, said device comprises:

[0029] - a hollow tube made of refractory material, called a refractory tube, forming a guide inside which a wire made of a metal or a metal alloy is intended to be arranged and / or to extend, preferably having a melting point greater than 800°C, - a wire unwinding / winding mechanism located upstream of the refractory tube, relative to a direction connecting the unwinding / winding mechanism to the refractory tube and arranged to put the wire in translation in the refractory tube.

[0030] - a control system arranged and / or programmed to, preferably from position information of a distal end of the wire, control the winding / unwinding of the wire so as to control the position of the distal end of the wire outside the refractory tube.

[0031] Preferably, the device is intended for the production of molten samples in a levitator. Preferably, the device is intended to cooperate with a levitator.

[0032] The device may comprise the wire made of metal or metal alloy.

[0033] Preferably, the device is intended to stabilize a molten sample in a levitator.

[0034] Preferably, the distal end of the wire is, preferably is intended to be, located outside the refractory tube, preferably downstream of the refractory tube, relative to a direction of unwinding of the wire.

[0035] Preferably, the distal end of the wire is intended to be melted.

[0036] Preferably, at least a portion of the hollow tube is intended to be positioned in the levitator.

[0037] Preferably, the distal end of the wire is intended to be positioned in the center of the levitator.

[0038] Preferably, the distal end of the wire is intended to be melted in the levitator.

[0039] The control system can be manual or automatic, i.e. controlled by a stand-alone control unit.

[0040] Preferably, the control system is arranged to control the winding / unwinding of the wire so that:

[0041] - to control the position of the distal end of the wire relative to the refractory tube, and / or

[0042] - to position the distal end of the wire in the center of the levitator.

[0043] Preferably, the control system is arranged to control the winding / unwinding of the wire, with respect to position information coming from a center of the levitator at which the distal end of the wire is intended to be positioned. Preferably, the device comprises a wire reserve located upstream of the wire unwinding / winding mechanism, with respect to a direction of unwinding of the wire, and / or an element for storing a wire reserve, for example a wire spool.

[0044] Preferably, the device is arranged to keep the wire slack, i.e. not to put tension on the wire, between the unwinding / winding mechanism and the wire reserve.

[0045] Preferably, the direction connecting the wire unwinding / winding mechanism to the refractory tube corresponds to a wire unwinding direction. Preferably, the wire unwinding direction corresponds to the direction in which the wire is unwound from the wire reserve to the refractory tube.

[0046] Preferably, the control system arranged and / or programmed to position a distal end of the wire in the levitator, into which the wire is intended to be introduced, so that the distal end of the wire intended to be melted is further stabilized by the levitator.

[0047] The position information may be data, for example data from an imaging system. The imaging system may be a camera and / or a spectroscopy system. The device may comprise an imaging system arranged to image the distal end of the wire, the images acquired by the system constituting the position information of the distal end of the wire.

[0048] Preferably, the wire unwinding / winding mechanism and / or the refractory tube is arranged to keep the wire straight downstream of said unwinding / winding mechanism.

[0049] Preferably, the wire unwinding / winding mechanism comprises at least one pair of rotating rollers arranged to grip the wire, said at least one pair of rotating rollers arranged to unwind / wind the wire and / or to exert pressure on the wire.

[0050] The at least one pair of rotating rollers or one of the pairs of rotating rollers may be arranged to exert pressure on the wire without being arranged to wind / unwind the wire. Preferably, at least one of the pairs of rotating rollers is arranged to exert pressure on the wire and to wind / unwind the wire. Preferably, the unwinding / winding mechanism comprises a fixed element and a movable element, the movable element being arranged to translate, relative to the fixed element, perpendicular to an axis of revolution of the refractory tube and / or to an axis of revolution of an additional hollow tube, called an additional tube. Preferably, for one, several or each of the pairs of rollers, one of the rollers of the at least one pair of rollers is mounted on a fixed element and the other of the rollers of the at least one pair of rollers is mounted on a movable element.

[0051] Preferably, an axis connecting the fixed element and the movable element and / or connecting a center of each of the two rollers of the at least one pair of rollers is perpendicular to an axis of revolution of the refractory tube and / or to an axis of revolution of the additional tube.

[0052] Preferably, the movable element is mounted on a slide arranged to guide the translation of the movable element.

[0053] Preferably, the unwinding / winding mechanism, and / or the arrangement of the movable element and the fixed element, is arranged to modulate and / or adapt a spacing between the fixed element and the movable element.

[0054] Preferably, the movable element is arranged so that the roller of the at least one pair of rollers mounted on the movable element is translated, relative to the fixed element, perpendicular to an axis of revolution of the refractory tube and / or to an axis of revolution of an additional tube and exerts pressure on the wire.

[0055] The unwinding / winding mechanism may comprise a device, called a compression device, arranged to modulate and / or adapt a spacing between the fixed element and the movable element and / or to translate the movable element relative to the fixed element and / or so that pressure is exerted on the wire by the rollers of the at least one pair of rollers. The compression device may be arranged to control and / or modulate and / or adapt the pressure exerted on the wire.

[0056] Thus, preferably, the unwinding / winding mechanism is adapted to wires of different diameters or adapts to wires of different diameters without the need to modify the unwinding / winding mechanism.

[0057] Preferably, the wire unwinding / winding mechanism is arranged to adapt the position of an area of ​​the wire on which pressure is exerted by the rotating rollers of one or more pairs of rollers on the wire. Preferably, the wire unwinding / winding mechanism is arranged to adapt the position of the area of ​​the wire, on which pressure is exerted by the rotating rollers of one or more pairs of rollers on the wire, between the unwinding / winding mechanism and the wire storage element.

[0058] Preferably, the movable element is arranged to modify and / or adapt and / or control a position of one or more pairs of rollers along the wire and / or the area of ​​the wire on which the rotating rollers of one or more pairs of rollers exert pressure on the wire.

[0059] Preferably, the device comprises a motor arranged to rotate one or each roller of the at least one pair of rotating rollers.

[0060] Preferably the motor is a stepper motor.

[0061] Preferably, the motor is mounted on the fixed element.

[0062] Preferably, the motor is arranged to rotate the roller mounted on the fixed element.

[0063] Preferably, the at least one pair of rollers is arranged to unwind / wind the wire by rotating one or each roller of one or more pairs of rotating rollers.

[0064] Preferably, the wire unwinding / winding mechanism is arranged to control and / or modulate and / or adapt a pressure exerted by the rotating rollers on the wire.

[0065] The unwinding / winding mechanism, and / or the fixed element and / or the movable element, is arranged so that one or more rotating rollers of the at least one pair of rollers are movable relative to the wire and / or relative to each other, preferably perpendicular to the axis along which the rotating rollers grip the wire.

[0066] Preferably, the unwinding / winding mechanism may comprise, and / or the compression device may comprise or consist of, a return element cooperating with one or more rotating rollers of the at least one pair of rollers and / or with the movable element and / or with the fixed element so that the at least one pair of rollers exerts pressure on the wire. Preferably, one of the two ends of the return element is fixed to the fixed element, or to a fixed part of the stabilizing device or the unwinding / winding mechanism, and the other of the two ends of the return element is fixed to the movable element. Preferably, the return element is arranged to modulate the pressure exerted by the rotating rollers on the wire.

[0067] Preferably, the return element is arranged to exert a return force so as to translate the fixed element towards the movable element and / or to translate one of the rollers of a pair of rollers towards the other of the rollers of the pair of rollers. Preferably, the return force is perpendicular to the axis of revolution of the refractory tube and / or to an axis of revolution of the additional tube and extends from the fixed element towards the movable element and / or from a center of one of the rollers of a pair of rollers towards a center of the other of the rollers of the pair of rollers.

[0068] The return element can be a spring.

[0069] Thus, preferably, the unwinding / winding mechanism is arranged to exert greater pressure on the wire as the wire diameter decreases so as to prevent the wire from slipping between the rollers.

[0070] Preferably, the device comprises the additional hollow tube, called additional tube, forming a guide inside which the wire is intended to be arranged and / or to extend and / or to be put in translation, the additional tube is arranged upstream of the wire unwinding / winding mechanism, relative to the direction connecting the unwinding / winding mechanism to the refractory tube, and an axis of revolution of the additional tube is mainly parallel to the axis of revolution of the refractory tube.

[0071] Preferably, the unwinding / winding mechanism is arranged to, more preferably the arrangement of the refractory tube, the wire unwinding / winding mechanism and / or the additional hollow tube, are arranged to, preferably one or one relative to the other or to the others to, adjust an axis along which the wire extends in the refractory tube mainly parallel to an axis of revolution of the refractory tube and / or an axis along which the distal end of the wire extends mainly parallel to an axis of revolution of the refractory tube.

[0072] The device comprises a levitation device, called a levitator, comprising an opening or passage, connecting the exterior to the interior of the levitator, through which the wire and / or the hollow tube of refractory material extends.

[0073] The levitator may be any type of levitator known from the prior art. By way of non-limiting example, the levitator may be an induction levitation device, an aerodynamic levitation device or an electrostatic levitation device.

[0074] Preferably, the levitator is an acoustic levitator.

[0075] Preferably, the levitator comprises a set of ultrasonic emitters, called transmitters, arranged to emit, each, an acoustic wave focused at a center of the levitator. The set of emitters is arranged to obtain standing acoustic waves whose intensity is maximum at the center of the levitator.

[0076] Preferably, the levitator comprises two facing domes.

[0077] Preferably, each dome includes:

[0078] - a first group of ultrasonic emitters, called transmitters, forming a cap extending between a pole and a stabilizer,

[0079] - a second group of ultrasonic emitters, called emitters, forming the stabilizer and extending from the dome towards a plane of the levitator, called the median plane, which is perpendicular to the axis connecting the pole of each of the domes, called the axis of revolution, and which is located equidistant from the two poles; the stabilizers are arranged to form at least two pairs of emitters each comprising two subgroups of radially opposite emitters, including a subgroup of emitters of the stabilizer of one dome and a subgroup of emitters of the stabilizer of the other dome, each subgroup of emitters comprising at least one emitter.

[0080] Preferably, the emitters of the cap of each of the domes are arranged to emit an acoustic wave having a first frequency fi and the emitters of the stabilizer of each of the domes are arranged to emit an acoustic wave having a frequency f2 different from fi.

[0081] Preferably, the two subgroups of transmitters of one of the pairs of transmitters are arranged to emit acoustic waves of which a phase differs from a phase of the acoustic waves emitted by the two subgroups of transmitters of another of the pairs.

[0082] Preferably, the levitator control system is arranged and / or programmed to, from position information of a distal end of the wire and / or information from the center of the levitator, position a distal end of the wire in the levitator so that the distal end of the wire intended to be melted and / or during its melting is stabilized by the levitator.

[0083] Position information of a distal end of the wire and / or information of the center of the levitator are referred to as information in this description. The information may be data from an imaging system. The imaging system may be an optical sensor or an optical system comprising an optical sensor, for example a camera.

[0084] The device comprises an imaging system arranged to image the distal end of the wire and / or the center of the levitator; the images acquired by the imaging system constitute the position information of the distal end of the wire.

[0085] Preferably, the ultrasonic transmitters are piezoelectric transmitters.

[0086] Preferably, the center of the acoustic device is a geometric center of the levitation device.

[0087] Preferably, the center of the levitation device is intersected by the emission axis of the acoustic wave emitted by each of the transmitters.

[0088] The domes can be ovoid in shape, preferably spherical in shape.

[0089] Preferably, the concave part of one dome is located opposite the concave part of the other dome.

[0090] Preferably, the first and second groups of emitters of a dome constitute the set of emitters of the dome.

[0091] Preferably, each emitter of the first group of emitters of one dome is radially opposite another emitter of the first group of emitters of the other dome. Preferably, each emitter of the second group of emitters of one dome is radially opposite another emitter of the second group of emitters of the other dome.

[0092] Preferably, the pole of a dome is or also constitutes a pole of the levitation device.

[0093] Preferably, the cap of a dome considered extends between the pole and the stabilizer of the dome considered in a direction extending from the pole of the dome considered towards the median plane.

[0094] Preferably, the axis connecting the pole of each of the domes is an axis of symmetry of the levitation device. The axis connecting the pole of each of the domes can be defined as the axis connecting the two poles of the levitation device.

[0095] Preferably, an object or sample to be analyzed is intended to levitate in the center of the levitation device.

[0096] Preferably, the phase of the wave emitted by one of the pairs of transmitters differs from the phases of the standing waves emitted by each of the other pairs of transmitters. Preferably, one pair of transmitters emits a standing wave having a phase different from a phase of a standing wave emitted by another of the pairs of transmitters. Preferably, each pair of transmitters emits a standing wave having a different phase.

[0097] Preferably, the levitator comprises a control system arranged and / or programmed to, from position information of a distal end of the wire and / or information from the center of the levitator, control the winding / unwinding of the wire so as to position the distal end of the wire, extending out of the refractory tube, at the center of the levitator.

[0098] Preferably, the levitator comprises a control unit arranged so that the phase of the acoustic wave emitted by the at least two pairs of transmitters increases or decreases, by successive increments, from a given pair of transmitters to an adjacent pair of transmitters.

[0099] Preferably, the frequency fi is at least 5 kHz higher or lower than the frequency f2.

[0100] According to the invention, a system for stabilizing and producing molten samples, called a system, is also proposed. The system comprises:

[0101] - the device for stabilizing molten samples according to the invention, and

[0102] - a system for melting the distal end of the wire.

[0103] Preferably, the fusion system is arranged to emit a laser beam whose trajectory intersects an area in which the distal end of the wire is intended to be positioned.

[0104] The system for melting the distal end of the wire may comprise or be based on the use of charged particles, for example ions or electrons. Preferably, the system for melting the distal end of the wire comprises or is based on the use of electromagnetic waves, for example a high-power optical source such as high-power LEDs or a halogen lamp.

[0105] Preferably, the system for melting the distal end of the wire comprises or consists of at least one laser arranged to emit a laser beam whose trajectory intersects the area in which the distal end of the wire is intended to be positioned. Preferably, when the stabilization system comprises the levitator and the melting system, the area in which the distal end of the wire is intended to be positioned is located in the center of the levitator.

[0106] According to the invention, there is also provided a levitation device, called a levitator, comprising the device for stabilizing molten samples according to the invention. The levitator comprises an opening or passage, connecting the exterior to the interior of the levitator, through which the wire and / or the hollow tube made of refractory material extends.

[0107] Preferably, the molten sample stabilization device according to the invention is suitable, more preferably is particularly suitable, more preferably is designed and particularly advantageously is specially designed, to cooperate with and / or to be mounted on the levitator according to the invention.

[0108] The levitator may be any type of levitator known from the prior art. By way of non-limiting example, the levitator may be an induction levitation device, an aerodynamic levitation device or an electrostatic levitation device.

[0109] Preferably, the levitator is an acoustic levitator as described in the present application.

[0110] Preferably, the levitator according to the invention is suitable, more preferably is particularly suitable, more preferably is designed and particularly advantageously is specially designed, to cooperate with and / or to be mounted on the molten sample stabilization device / or on the molten sample stabilization and production system according to the invention.

[0111] According to the invention, a method for stabilizing molten samples is also proposed. The method for stabilizing molten samples comprises: - guiding a wire made of a metal or a metal alloy in a hollow tube made of refractory material, called a refractory tube, forming a guide inside which the wire is intended to be arranged,

[0112] - a translation of the wire in the refractory tube by means of a wire unwinding / winding mechanism located upstream of the refractory tube, relative to a direction connecting the unwinding / winding mechanism to the refractory tube,

[0113] - a control system for winding / unwinding the wire so as to control the position of a distal end of the wire, intended to be melted, outside the refractory tube.

[0114] According to the invention, a method for stabilizing and producing molten samples is also provided. The method for stabilizing and producing molten samples comprises: the method for stabilizing molten samples according to the invention, melting a distal end of the wire intended to be melted.

[0115] Preferably, the method for stabilizing and producing molten samples comprises a step of arranging the distal end of the wire in the center of a levitation device, called a levitator, so that, during operation of the levitator, the levitator also contributes to stabilizing the distal, molten end of the wire.

[0116] Preferably, the method of stabilizing and producing molten samples comprises unwinding the wire to increase a volume of the molten distal end of the wire until the molten distal end is detached such that a drop of molten metal or metal alloy levitates in the levitator.

[0117] Preferably, the molten sample stabilization device / or the molten sample stabilization and production system according to the invention is suitable, more preferably is particularly suitable, more preferably is designed and particularly advantageously is specially designed, for implementing the molten sample stabilization method and / or the molten sample stabilization and production method. Also, any feature of the molten sample stabilization device / or the molten sample stabilization and production system according to the invention is directly transferable to the molten sample stabilization method and / or the molten sample stabilization and production method and vice versa.

[0118] Description of figures

[0119] Other advantages and features of the invention will become apparent upon reading the detailed description of implementations and embodiments which are in no way limiting, and the following appended drawings: FIGURE 1 is a schematic representation in side view of an embodiment of a device for stabilizing molten samples according to the invention, FIGURE 2 is a schematic representation in side view of an embodiment of the system for stabilizing and producing molten samples according to the invention, FIGURE 3 is a schematic representation in side view of an improvement of the embodiment of the system for stabilizing and producing molten samples according to the invention presented in FIGURE 2, FIGURE 4 is a schematic representation of a section in side view of an embodiment of the acoustic levitation device according to the embodiment,FIGURE 5 is a schematic representation in side view illustrating the levitator caps and the couples of the stabilizers of the acoustic levitation device according to the embodiment, FIGURE 6 is a graph illustrating the evolution of the temperature of a molten sample, maintained in levitation by the stabilization device according to the invention, as a function of time, FIGURE 7A is a photograph, acquired in the visible range by a CCD camera, of the molten sample maintained in levitation in the device according to the invention, FIGURE 7B is a photograph, acquired in the visible range by a CCD camera, of the molten sample maintained in levitation in the device according to the invention, FIGURE 7C is a photograph, acquired in the infrared range by a thermal camera, of the molten sample maintained in levitation in the device according to the invention. Description of the embodiments,

[0120] The embodiments described below being in no way limiting, it will be possible in particular to consider variants of the invention comprising only a selection of the described characteristics, isolated from the other described characteristics (even if this selection is isolated within a sentence comprising these other characteristics), if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art. This selection comprises at least one characteristic, preferably functional without structural details, or with only a part of the structural details if this part only is sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art.

[0121] With reference to FIGURE 1, an embodiment of the molten sample stabilization device 1 is presented. The device 1 comprises a hollow tube 2 made of refractory material, called refractory tube 2. The refractory tube 2 is made of alumina according to the embodiment. The refractory tube 2 forms a guide inside which a wire 3 made of a metal being qualified as pure, that is to say having an impurity level of less than 1000 ppm, or of a metal alloy is intended to be arranged. The device 1 also comprises a mechanism 4 for unwinding / winding the wire 3. The unwinding / winding mechanism 4 is located upstream of the refractory tube 3 relative to the direction connecting the unwinding / winding mechanism 4 to the refractory tube 3 and to the direction of unwinding of the wire 3. The unwinding / winding mechanism 4 is arranged to translate the wire 3 in the refractory tube 2.The device 1 comprises a control system 10 arranged and / or programmed to control the winding / unwinding of the wire so as to control the position of a distal end 31 of the wire 3 outside the refractory tube 2. The refractory tube 2 makes it possible to expose only the distal end 31 of the wire 3 and to limit the exposure to heat of the part of the wire 3 located upstream of the distal end 31 of the wire 3. However, increasing the length of the refractory tube 2, i.e. the dimension of the refractory tube 2 extending along the axis of revolution of the refractory tube 2, has the effect of introducing friction of the wire 3 on the internal wall of the refractory tube 2 and / or bending of the wire 3 upstream of the refractory tube 2 by buckling of the wire 3. The length of the refractory tube must therefore not be too high. The refractory tube 2 helps avoid these problems.Furthermore, positioning the refractory tube 2 in the immediate vicinity of the heating zone further avoids these problems.

[0122] According to the non-limiting embodiment, the refractory tube has an outer diameter of approximately 3 mm, an inner diameter of approximately 1.25 mm and a length of the order of 115 mm. The additional tube 12 has an outer diameter of approximately 4 mm, an inner diameter of approximately 2.5 mm and a length of the order of 95 mm.

[0123] The end 31 of the wire 3 is intended to be melted so that analyses can be carried out on the molten metal or metal alloy. The analyses can be carried out by analyzing images of the end 31 of the molten wire 3 and / or by analyzing electromagnetic waves, for example infrared or X-ray fluorescence, emitted by the end 31 of the molten wire 3. In practice, a drop of molten metal or metal alloy is formed.

[0124] In the absence of a stabilizing device 1 according to the invention, the melting of the end 31 of the wire 3 results in an uncontrolled increase in the size of the drop formed. Also, the control and adjustment of the position of the distal end 31 of the wire 3 outside the refractory tube 2, by the unwinding / winding mechanism 4, is necessary.

[0125] Furthermore, when heating the distal end 31 of the wire 3, the absence of a refractory tube 2 may induce movement of the end 31 of the wire 3 resulting in uncontrolled, non-homogeneous or non-optimal heating, and therefore maintenance of fusion. For this purpose, it is preferable to keep the end 31 of the wire 3 close to the distal end 21 of the refractory tube 2. Typically a distance of between 1 mm and 9 mm is suitable and a preferred distance of between 3 and 15 mm.

[0126] Furthermore, once the metal or metal alloy drop 18 has been formed, the latter tends to rise, by capillarity, on the wire 3. Also, the unwinding / winding mechanism 4 of the wire 3 makes it possible to adjust the position of the distal end 31 of the wire 3 as a function of this movement of the drop 18 on the wire 3. Furthermore, it is preferable that, when using the device 1, an axis of revolution of the refractory tube 2, or an axis of revolution or longitudinal of the channel passing through the refractory tube 2, is parallel to the vertical or to gravity so that the gravitational force exerted on the drop 18 is opposed to the capillary forces tending to make the drop 18 rise along the wire 3. The unwinding / winding mechanism 4 of the wire 3 comprises at least one pair 5 of rotating rollers 51, 52, a single pair 5 according to the embodiment, arranged to clamp the wire 3. The pair 5 of rotating rollers 51, 52 is arranged to unwind / wind the wire 3.The pair 5 of rotating rollers 51, 52 is also arranged to exert pressure on the wire 3. An axis connecting a center of each of the two rotating rollers 51, 52, this axis is parallel to the direction noted x in FIGURE 1, is perpendicular to the axis of revolution of the refractory tube 3.

[0127] The arrangement of the unwinding / winding mechanism 4 of the wire 3 and the refractory tube 2 makes it possible to keep the wire 3 straight downstream of said unwinding / winding mechanism 4. Indeed, the pressure exerted by the unwinding / winding mechanism 4 of the wire 3 has the effect of straightening the wire 3 as it passes between the rollers 51, 52. In combination, the channel passing through the refractory tube 3 inside which the wire 3 translates downstream of the mechanism 4 makes it possible to force the wire 3 to maintain a mainly straight shape.

[0128] According to the non-limiting embodiment, the rotating rollers 51, 52 have a diameter of the order of 15 mm and a width, that is to say the dimension of the rotating rollers 51, 52 along their axis of revolution, of approximately 10 mm.

[0129] In order to further improve the achievement of the mainly rectilinear shape of the wire 3 downstream of the refractory tube 2, the device 1 comprises an additional hollow tube 12, called additional tube 12, forming a guide inside which the wire 3 is intended to be arranged. The additional tube 12 is made of metal, brass according to the embodiment. There is nothing to prevent the additional tube 12 from being made of a material having a greater refractory power, such as ceramic. In addition, the ceramic offers very good resistance to friction of the wire 3 on the internal wall of the refractory tube 2 likely to appear during the winding / unwinding of the wire 3. However, the metal offers sufficient resistance to friction. The additional tube 12 is arranged upstream of the unwinding / winding mechanism 4 of the wire 3, relative to the direction connecting the unwinding / winding mechanism 4 to the refractory tube 2 and to the unwinding direction of the wire 3.The axis of revolution of the additional tube 12 is parallel to the axis of revolution of the refractory tube 3. The additional tube 12 also makes it possible to avoid kinking, folding or breaking of the wire 3 during its winding / unwinding. The additional tube 12 being further away than the refractory tube 2 from the heating zone, it undergoes moderate heating, or even negligible heating in certain cases. The additional tube 12 could be, when the temperature at the additional tube 12 is sufficiently low, made of a polymer, preferably a heat-resistant polymer, such as polyamide, Teflon or polyetheretherketone (PEEK).

[0130] The unwinding / winding mechanism 4 comprises a fixed element 6 and a movable element 7. One of the rollers 52 of the pair 5 of rollers 51, 52 is fixedly mounted on the fixed element 6 and the other of the rollers 51 of the pair 5 of rollers 51, 52 is fixedly mounted on the movable element 7. The movable element 7 is arranged to translate perpendicularly to the axis of revolution of the refractory tube 2. Thus, the roller 52 is fixed and the roller 51 is movable relative to the roller 52. In this way, the wire 3 is clamped between the movable roller 51 and the fixed roller 52. According to the non-limiting embodiment, it is the movable element 7 which ensures the translation of the movable roller 51 relative to the fixed roller 52. Any means of guiding in translation 11 of the movable element 7 or of the roller 51 can be envisaged. such as, for example, an arm or a rod on or along which the movable element 7 or the roller 51 slides.According to the embodiment, the movable element 7 is guided by a slide 8 in which it slides.

[0131] The device 1 comprises a motor 8 arranged to rotate the fixed rotating roller 52 of the pair 5 of rotating rollers 51, 52. Thus, associated with the pressure exerted on the wire 3 by the pair 5 of rollers, the rotation of the roller 52 makes it possible to unwind and wind the wire 3. The motor 8 is fixedly mounted on the fixed element 6 and drives the rotation of the roller 52. According to the embodiment, an electronic control module 9 controls the motor 8. The controller 9 is connected to the control system 10 which makes it possible to control and command the motor 8. The motor 8 can be, for example, a stepper motor 8.

[0132] The unwinding / winding mechanism 4 of the wire 3 is arranged to modulate the pressure exerted, noted P, by the rotating rollers 51, 52 on the wire 3. The pressure P exerted is modulated by adapting the force exerted on the wire 3 by the translation means 11 of the movable element 7. It has been noted that a reduction in the diameter of the wire 3 causes slippage of the wire 3 when the rollers 51, 52 are rotated and therefore defects in the winding / unwinding of the wire 3. Also, it is preferable to increase the pressure (or force) exerted on the wire 3 when the diameter of the wire 3 decreases.

[0133] According to the non-limiting embodiment, the translation means 11 of the movable element 7 is a return means 11, a spring 11 for example. Still according to the non-limiting embodiment, the unwinding / winding mechanism 4 of the wire 3 comprises two springs 11. Each spring 11 has a stiffness of approximately 300 N.nr 1and a restoring force of the order of 11 N.

[0134] The unwinding / winding mechanism 4 may be mounted on a fixed element 19, such as a support 19, for example a bracket 19 or an arm. The unwinding / winding mechanism 4 may be arranged to be put into translation and / or rotation relative to the fixed element 19, for example by being mounted on a plate itself mounted movably on the fixed element 19.

[0135] Therefore, the person skilled in the art will understand that the arrangement of the unwinding / winding mechanism 4 to be put in translation and / or in rotation relative to the fixed element 19 makes it possible to adjust and / or control and / or command the horizontal position and / or the vertical position of the wire 3, and in particular of the distal end 31 of the wire 3.

[0136] With reference to FIGURES 2 and 3, two embodiments of a system for stabilizing and producing molten samples 13, called stabilization system 13, are also described.

[0137] According to the embodiment, the system 13 comprises the molten sample stabilization device 1 according to the invention. The stabilization system 13 further comprises a system 14 for melting the distal end 31 of the wire 3. The melting system 14 is arranged to emit an electromagnetic beam 15 or elementary particles 15 capable of heating the wire to a temperature above 800°C, such as for example ions or electrons. The electromagnetic beam 15 or elementary particle beam 15 intersects the zone in which the distal end 31 of the wire 3 is intended to be positioned outside the refractory tube 2. The melting system 14 is arranged to control the trajectory of the beam 15 so as to intersect the zone in which the distal end 31 of the wire 3 is intended to be positioned outside the refractory tube 2 if the position of the zone in space is modified or must be modified.The melting system 14 of the distal end 31 of the wire 3 is a laser 14 according to the non-limiting embodiment. The laser 14 is arranged to emit a laser beam 15. Thus, during the melting of the distal end 31 of the wire 3, a drop 18 of liquid metal or liquid metal alloy is formed.

[0138] Referring to FIGURE 4, in an improvement of the invention, the system 13 further comprises a levitator 16. Any known type of levitator 16 can be used. Indeed, no levitator allows a drop of molten metal 18 to be kept self-supported, that is to say not connected to a wire 3, for a time sufficient to study the drop 18. Indeed, disturbances eventually cause destabilization and loss of levitation of the drop 18. The use of the molten sample stabilization device 1 according to the invention in combination with a levitator 16 makes it possible to keep the drop 18 levitated for longer times than the levitator 16 used alone. The drop 18 is maintained in a given and selected area of ​​space for a longer time. Further, the levitator 16 includes an opening connecting the exterior to the interior of the levitator 16 through which the refractory tube 2 extends.Most levitators 16 necessarily include an opening, this is particularly the case for levitators 16 comprising two facing domes 41, 42.

[0139] Furthermore, it is preferable to use an acoustic levitator. It is particularly advantageous to use an acoustic levitator 16 as shown in FIGURES 4 and 5 and described in detail below. When using an acoustic levitator 16, it is preferable that the melting system 14 is contactless and not based on the use of a material flow, in particular a gas flow such as a flame. This is because the gases are repelled by the waves of the levitator 16, and in particular in the case of acoustic levitators 16.

[0140] The stabilization system 13 or the molten sample stabilization device 1 may be coupled to or may comprise an optical system 17 arranged to image the area in which the distal end 31 of the wire 3 is located. By imaging the distal end 31 of the wire 3, it may be understood the acquisition of an electromagnetic wave originating from or emitted by the drop 18.

[0141] Furthermore, the data from the optical system 17 can also be used to control and / or adjust the position of the distal end 31 of the wire 3, via the unwinding / winding mechanism 4 of the wire 3, and / or to control and / or adjust the temperature of the drop 18, via the melting system 14.

[0142] According to the invention, the wire 3 is not part of the stabilization system 13 or the stabilization device 1. The wire 3 is intended to cooperate with the stabilization system 13 and the stabilization device 1 when the latter are used. It is appropriate to ensure that the wire 3 has a diameter allowing it to be sufficiently flexible without being too rigid. For example, the wire may have a diameter of between 0.05 and 0.5 mm, preferably between 0.1 and 0.25 mm. A ratio between the internal diameter, i.e. the diameter of the through channel, of the refractory tube 2 and the additional tube 12 and the diameter of the wire 3 may be between two and ten to reduce the friction of the wire 3 against the internal walls of the refractory tube 2 and the additional tube 12 while allowing the wire 3 to be held straight.

[0143] With reference to FIGURES 4 and 5, an advantageous embodiment of an acoustic levitator 16, referred to as levitator 16 in the remainder of the description below, according to the invention, is described. Although the levitator 16 presented, used alone, makes it possible to maintain a drop 18 self-supported, that is to say not connected to a wire 3, for a time of a few minutes, or even ten minutes, disturbances end up causing a destabilization of the levitation of the drop 18. There is therefore a need to further stabilize the drop 18. For this purpose, the levitator 16 presented below, when in combination with the molten sample stabilization device 1 according to the invention makes it possible to keep the drop 18 levitated as long as necessary. The drop 18 is maintained in a given and chosen area of ​​space without time limit.

[0144] The levitator 16 comprises a set of ultrasonic transmitters 20, called transmitters 20. The transmitters 20 are arranged to each emit an acoustic wave focused at the center 30 of the levitator 16. The ultrasonic transmitters 20 used are manufactured by Manorshi® under the references MSO-P1640H12T and MSO-P1625H12T. The set of transmitters 20 is arranged to obtain standing acoustic waves whose intensity is maximum at the center 30 of the levitator 16. The embodiment presented is a non-limiting example of a possible arrangement of the transmitters 20. Those skilled in the art will understand the concept of a standing acoustic wave as being a superposition of two acoustic waves, propagating along the same axis and in an opposite direction, whose zero-pressure nodes are fixed in space. According to the non-limiting embodiment, the levitator 16 comprises fifty-eight transmitters 20.Each emitter 20 of a dome 41, 42 is radially opposite a different emitter 20 of the other dome 41, 42.

[0145] The levitator 16 comprises two domes 41, 42 facing each other. An axis of revolution 50 connects the poles 61, 62 of each of the domes 41, 42. A median plane 70 perpendicular to the axis of revolution 50 is located equidistant between the poles 61, 62. According to the embodiment, the domes 41, 42 are spherical.

[0146] Each dome 41, 42 comprises a first group 411, 421 of emitters 20 forming a cap 81, 82 extending between a pole 61, 62 and a stabilizer 91, 92. The first group 411, 421 of each cap 81, 82 of each dome 41, 42 comprises 54 emitters. Each emitter 20 of a cap 81, 82 of a dome 41, 42 is radially opposite a different emitter 20 of the other cap 81, 82 of the other dome 41, 42.

[0147] Each dome 41, 42 comprises a second group 412, 422 of emitters 20 forming the stabilizer 91, 92. The second group 412, 422 of emitters 20 extends between the cap 81, 82 of each dome 41, 42 and in the direction of the median plane 70. The second group 412, 422 of emitters of each cap 81, 82 of each dome 41, 42 comprises 54 emitters. Each emitter 20 of a stabilizer 91, 92 of a dome 41, 42 is radially opposite a different emitter 20 of the other stabilizer 91, 92 of the other dome 41, 42.

[0148] According to the embodiment and advantageously, the emitters 20 of the first group 411, 421 cover or form a paving of or are distributed over, preferably evenly or homogeneously, the whole of each cap 81, 82. According to the embodiment and advantageously, the emitters 20 of the second group 412, 422 cover or form a paving of or are distributed over, preferably evenly or homogeneously, the whole of each stabilizer 91, 92.

[0149] According to the non-limiting embodiment, the first group 411, 421 of emitters 20 of each dome 41, 42 comprises six rings of emitters 20, one center of which coincides with the axis of revolution 50. The second group 412, 422 of emitters 20 comprises two rings of emitters 20, one center of which coincides with the axis of revolution 50. The center 30 of the levitator 16 is located at a distance of approximately eight centimeters (cm) from the emitters 20. The levitator 16 according to the embodiment is arranged for samples whose size is between one and three millimeters (mm). Any type of sample, and in particular high-density samples, for example Platinum with a density of 21.5, could be levitated in a controlled manner with the levitator 16 according to the invention.

[0150] The levitator 16 comprises a volume or a space zone 100, extending between the two domes 41, 42, devoid of emitters 20. The space zone 100 constitutes a portion of a sphere 100 or a ring 100. The portion of a sphere 100 comprises the median plane 70. The portion of a sphere 100 extends between the two stabilizers 91, 92. Preferably, the portion of a sphere 100 is devoid of any solid element or solid part. Thus, the portion of a sphere 100 constitutes or forms an annular opening 100 offering 360° access to the center 30 of the levitator 16. In this way, access to the center 30 of the levitator 16 is possible over the entire periphery of the levitator 16.

[0151] Those skilled in the art will understand that the acoustic device 16 is intended to be powered by one or more power supplies without the latter necessarily being an integral part of the invention. In practice, and in a non-limiting manner, the caps 81, 82 are intended to be powered by a power supply separate from the power supply intended to power the stabilizers 91, 92. The levitator 16 may comprise a control unit and / or a processing unit without the latter necessarily being an integral part of the invention. The control unit may be arranged, among other things, to control and / or modulate the output parameters, for example a voltage and / or a frequency and / or a phase and / or a power of a signal intended to power one or more transmitters 20, of the power supply(s). By way of non-limiting example, the control unit may be or may comprise a microcontroller.

[0152] The levitation of an object under the effect of acoustic waves causes instabilities and disturbances inherent in the process of levitation by acoustic waves to appear, in particular due to the geometric irregularities of the sample. In addition, under certain experimental conditions of study of the sample, in particular when it is heated or a fortiori melted, additional instabilities, such as for example flows of hot gases and the geometric deformation of the sample, appear. To overcome these instabilities and disturbances, the emitters 20 of the cap 81, 82 of each of the domes 41, 42 emit an acoustic wave having a first frequency fi and the emitters 20 of the stabilizer 91, 92 of each of the domes 41, 42 emit an acoustic wave having a frequency f2 different from fi.According to the non-limiting embodiment, the acoustic waves emitted by the caps 81, 82 have the same frequency f1 which is 40 kHz and the acoustic waves emitted by the stabilizers 91, 92 have the same frequency f2 which is 25 kHz. This characteristic makes it possible to avoid coupling between the acoustic waves emitted by the caps 81, 82 and the acoustic waves emitted by the stabilizers 91, 92. Thus, this characteristic makes it possible to decorrelate the effect of the caps 81, 82 from the effect of the stabilizers 91, 92. This absence of coupling allows the arrangement of the caps 81, 82 to have the effect of levitating the object by countering gravity. This absence of coupling allows the arrangement of the stabilizers 91, 92 to have the effect of laterally stabilizing the object by countering instabilities or disturbances in the horizontal plane.This provides increased control of the levitation and makes it possible to confine the sample to the center 30 of the levitator 16, limiting or even eliminating lateral movements of the sample. It should be noted that the frequency f1 could just as easily be lower than the frequency f2. Those skilled in the art will know how to adapt the frequencies according to the size of the sample intended to levitate.

[0153] The levitation of liquid objects under the effect of acoustic waves also causes a vertical crushing or flattening of the sample under the effect of its own weight and under the effect of the acoustic waves, countering the effect of gravity, ensuring the levitation of the sample. This effect is inherent in the acoustic levitation devices of the state of the art. The characteristic of the levitation device 1 according to which the emitters 20 of the cap 81, 82 of each of the domes 41, 42 emit an acoustic wave which has a frequency f1 different from a frequency f2 of a wave emitted by the emitters 20 of the stabilizer 91, 92 also makes it possible to overcome this effect of crushing the poles of the levitating sample.

[0154] The emitters 20 of the second group 412, 422 of emitters of each dome 41, 42 are arranged so that the stabilizers 91, 92 form at least two pairs of emitters 20. For example, the use of two pairs of emitters will make it possible to act on two lateral directions, preferably perpendicular. The use of three pairs of emitters will make it possible to act on three lateral directions, preferably forming an angle of 120° between them.

[0155] According to the embodiment, the stabilizers 91, 92 form six pairs 93, 94, 95, 96, 97, 98 of emitters 20 according to the non-limiting embodiment. Two pairs of emitters 20 are sufficient to obtain the expected minimum effect of controlled lateral stabilization. Six pairs 93, 94, 95, 96, 97, 98 of emitters 20 allow better lateral control of the sample and offer a good compromise between control of the lateral stabilization and complexity of the electronics required for the control of the emitters 20 of the pairs 93, 94, 95, 96, 97, 98. However, there is nothing to prevent using a larger number of pairs of emitters 20 to provide increased control of the lateral stabilization. Each pair 93, 94, 95, 96, 97, 98 of transmitters 20 is formed by two sub-groups 931, 932, 941, 942, 951, 952, 961, 962, 971, 972, 981, 982 of transmitters 20 opposite the second groups 412, 422 of transmitters.Each pair 93, 94, 95, 96, 97, 98 of emitters comprises a subgroup 931, 941, 951, 961, 971, 981 of emitters 20 of the stabilizer 91 of the dome 41 and a subgroup 932, 942, 952, 962, 972, 982 of emitters 20 of the stabilizer 92 of the dome 42. The two subgroups 931, 932, 941, 942, 951, 952, 961, 962, 971, 972, 981 and 982 of emitters 20 of a pair 93, 94, 95, 96, 97, 98 20 transmitters are located on either side of the median plane. A subgroup 931, 932, 941, 942, 951 of emitters 20 of a pair 93, 94, 95, 96, 97, 98 belongs to the stabilizer 91 of a dome 41 and is opposite the other subgroup 932, 942, 952, 962, 972, 982 of emitters 20 of the pair 93, 94, 95, 96, 97, 98 which belongs to the stabilizer 92 of the other dome 42. Each subgroup 931, 932, 941, 942, 951, 952, 961, 962, 971, 972, 981, 982 of emitters 20 comprises at least one transmitter 20.Each subgroup 931, 932, 941, 942, 951, 952, 961, 962, 971, 972, 981, 982 of transmitters 20 comprises 9 transmitters 20 according to the non-limiting embodiment.

[0156] Advantageously, the stabilizers 91, 92 are arranged to form at least one pair of pairs of transmitters 20. According to the embodiment in which the stabilizers 91, 92 form six pairs 93 to 98 of transmitters 20, the stabilizers 91, 92 are further arranged to form three pairs 93-96, 94-97 and 95-98 of pairs of transmitters 20. Each pair 93-96, 94-97, 95-98 of pairs is arranged so that each subgroup 931 to 981 of a pair 93 to 98 of a pair 93-96, 94-97, 95-98 of pairs considered is located opposite a subgroup 932 to 982 of the other pair 93 to 98 of the pair of couples considered.In other words, according to the embodiment, for the pair of couples 93-96, the subgroup 931, which is included in the stabilizer 91, of the couple 93 is radially opposite to the subgroup 962, which is included in the stabilizer 92, of the couple 96 and the subgroup 961, which is included in the stabilizer 91, of the couple 96 is radially opposite to the subgroup 932, which is included in the stabilizer 92, of the couple 93. For the pair of couples 94-97, the subgroup 941, which is included in the stabilizer 91, of the couple 94 is radially opposite to the subgroup 972, which is included in the stabilizer 92, of the couple 97 and the subgroup 971, which is included in the stabilizer 91, of the couple 97 is radially opposite to subgroup 942, which is included in stabilizer 92, of couple 94.For the pair of couples 95-98, the subgroup 951, which is included in the stabilizer 91, of the couple 95 is radially opposite the subgroup 982, which is included in the stabilizer 92, of the couple 98 and the subgroup 981, which is included in the stabilizer 91, of the couple 98 is radially opposite the subgroup 952, which is included in the stabilizer 92, of the couple 95.

[0157] The arrangement of the pairs 93 to 98 makes it possible to stabilize laterally, that is to say perpendicular to the axis of revolution 50, and in a controlled manner, the levitating object by acting on the levitating object in several lateral directions independently. It should be noted that this effect is made possible due to the absence of coupling between the acoustic waves emitted by the emitters 20 of the caps 81, 82 and the acoustic waves emitted by the emitters 20 of the stabilizers 91, 92.

[0158] In other words, considering as an example the pair 93-96 of couples 93, 96 of emitters 20 whose subgroups 931 and 932 of the pair 93 are each radially opposite, respectively, to the subgroup 962 and 961. The pair 93-96 of couples 93, 96, considered independently of the other pairs 94-97, 95-98 of couples 94, 95, 96, 97, 98, makes it possible to stabilize the levitating object laterally by acting on the levitating object in the first lateral direction included in the plane of FIGURES 4 and 5, including the center 30 of the levitator 16, perpendicular to the axis of revolution 50 and included in the median plane 70. Also, the use of the pair 93-96 of couples 93 and 96 makes it possible to stabilize laterally the levitating object by acting on the levitating object in the first lateral direction.The description given in this paragraph is transposable to the other pairs 94-97 and 95-98 of couples 94, 95, 96, 97, 98 of transmitters 20 and to the respective lateral stabilization directions.

[0159] Advantageously, the use of the pair 93-96 of pairs of emitters 20, considered independently of the other pairs 94-97, 95-98 of pairs, makes it possible to further improve the lateral stabilization of the levitating object by acting on the levitating object in the first lateral direction. In this case, preferably, a phase of the acoustic waves emitted by the emitters 20 of the subgroups 931 and 932 of the pair 93 is identical and a phase of the acoustic waves emitted by the emitters 20 of the subgroups 961 and 962 of the pair 96 is identical. The description given in this paragraph is transposable to the other pairs 94-97, 95-98 of pairs of emitters 20 and to the respective lateral stabilization directions. Also, in a preferred embodiment, a phase of the acoustic waves emitted by the transmitters 20 of the two subgroups 931-932, 941-942, 951-952, 961-962, 971-972 and 981-982 of each of the pairs 93, 94, 95, 96, 97 and 98 is identical.

[0160] Levitation of an object under the effect of acoustic waves causes the rotation of the object to be levitated due to the change in angular momentum of the waves when they are reflected and scattered by the sample. To compensate for this rotation, and considering the pair 93 of emitters 20, the phase of the acoustic waves emitted by the subgroups 931, 932 of emitters 20 differs from the phase of the acoustic waves emitted by at least one other subgroup 941, 942, 951, 952, 961, 962, 971, 972, 981, 982 of emitters 20 of at least one other of the pairs 94, 95, 96, 97, 98. Preferably, to counter the rotation of the object, the phase of the acoustic waves emitted by the pairs 93 and 96 of couples is identical and differs from the phase of the acoustic waves emitted by at least one of the other two of the pairs 94-97 and 95-98.According to the non-limiting embodiment, in a particularly advantageous manner, each pair 93, 94 and 95 of a pair of pairs 93-96, 94,-97 and 95-98 emits an acoustic wave in phase opposition with the other of the pairs 96, 97 and 98 of the pair of pairs considered. This characteristic also makes it possible to stabilize the object laterally, that is to say perpendicular to the axis of revolution, even more by countering the instabilities and disturbances inherent in the process of levitating an object intended to levitate by acoustic waves. Such a levitator 16 therefore makes it possible to completely manipulate an object without direct contact with the object. It is thus possible to position the object, that is to say to orient it, to pivot it and / or to translate it, to allow its observation and / or its analysis and / or to subject it to local processing without resorting to direct interaction with the latter.

[0161] Even more advantageously, to compensate for the rotation of the object to be levitated, it is appropriate that the phase of the acoustic wave emitted by at least one pair 93, 94, 95, 96, 97, 98 of transmitters 20 considered is greater or less than the phase of the acoustic wave emitted by a pair 93, 94, 95, 96, 97, 98 of transmitters 20 which is adjacent, by rotation relative to the axis of revolution 50, to the pair of transmitters considered. More preferably, but not necessarily, the two pairs 93-96, 94,-97 and 95-98 of a pair of pairs emit acoustic waves in phase opposition and each of the pairs 93-96, 94,-97 and 95-98 of pairs of emitters 20 emits an acoustic wave whose phase is higher or lower than the phase of the acoustic wave emitted by the pair of pairs of emitters 20 which is adjacent to it, by rotation in the clockwise or counterclockwise direction relative to the axis of revolution 50.

[0162] Furthermore, to improve the effect of compensating for the rotation of the object to be levitated and / or of rotating an object intended to levitate, it is advantageous, preferably by combining the arrangement of the pairs 93, 94, 95, 96, 97, 98 of emitters 20 and / or the arrangement of the pairs of pairs 93-96, 94,-97 and 95-98 of emitters 20 as described above, that the phase of the acoustic wave emitted by at least one pair 93, 94, 95, 96, 97, 98 of emitters 20 considered increases or decreases by successive incrementation of a pair 93, 94, 95, 96, 97, 98 of emitters 20 considered to a pair of emitters 20 which is adjacent to it by rotation relative to the axis of revolution. 50.More preferably, but not necessarily, the pairs 93-96, 94,-97 and 95-98 of a pair of pairs emit acoustic waves in phase opposition and the phase of the acoustic wave emitted by each of the pairs 93-96, 94,-97 and 95-98 of pairs of emitters 20 increases or decreases by successive incrementation from a pair 93-96, 94,-97 and 95-98 of pairs of emitters 20 to an adjacent pair of pairs 93-96, 94,-97 and 95-98 of emitters 20 by rotation relative to the axis of revolution 50.

[0163] The effect of stabilization of the levitating molten sample 18 provided by the stabilization device 1 is illustrated in FIGURE 6.

[0164] The results illustrated in FIGURE 6 were obtained by the molten sample stabilization and production system 13 according to the invention in order to illustrate the effects provided by the stabilization device 1 according to the invention. The time, in seconds, is plotted on the abscissa axis and the temperature in degrees Celsius is plotted on the ordinate axis of FIGURE 6.

[0165] The molten sample 18, i.e. the drop of molten metal 18, is copper according to the embodiment. In practice, it is the distal end 31 of the wire 3 which is melted by the melting system 14 to form a drop of molten liquid metal 18.

[0166] The graph in FIGURE 6 illustrates the evolution of the temperature of the molten sample 18 maintained in levitation by the stabilization device 1 according to the invention, as a function of time.

[0167] The molten sample 18 forms a droplet.

[0168] Thus, the translation and / or rotation of the unwinding / winding mechanism 4, preferably relative to the fixed element 19, makes it possible to adjust and / or control and / or command the horizontal position and / or the vertical position of the distal end 31 of the wire 3. Consequently, the horizontal position and / or the vertical position of the drop of molten metal 18 is also adjustable, in particular so that it coincides with the center 30 of the levitator 16, so as to improve the stabilization and / or the maintenance in levitation of the drop of molten metal 18.

[0169] The molten sample 18 is kept in levitation, in the levitator 16, by the stabilization device 1, for a period greater than 20 minutes. The inventors have observed that the molten sample 18 can be kept in levitation without time limitation by the stabilization device 1 according to the invention.

[0170] FIGURE 6 demonstrates that the levitation instabilities and disturbances inherent in the acoustic wave levitation process are resolved by the stabilization device 1 according to the invention.

[0171] Those skilled in the art will understand that maintaining the levitation of the molten sample 18 for such durations is only possible in the presence of the levitator 16.

[0172] The photographs or images illustrated in FIGURES 7 illustrate a molten sample 18 kept in levitation by the device 1 according to the invention. The wire 3, and therefore the molten drop 18, is made of copper according to the embodiment.

[0173] FIGURES 7A and 7B are images or photographs acquired by a CCD (Charge Coupled Device) type photographic sensor. FIGURE 7C illustrates a photograph or image obtained in the infrared domain by a CCD sensor. The images illustrated in FIGURE 7 were obtained by the system for stabilizing and producing molten samples 13 according to the invention to illustrate the effects provided by the stabilization device 1 according to the invention.

[0174] According to the embodiment, it is observed, in each of the photographs of FIGURES 7A to 7C, that the wire 3 is always connected by its end 31 to the molten sample 18.

[0175] The sample forms a droplet. It can be seen in FIGURES 7, and in particular in FIGURE 7C, that the molten sample 18, i.e. the drop of molten metal 18, is suspended or attached to the distal end 31 of the wire 3 (shown in dotted lines). The distal end 31 of the wire 3 is at a lower temperature and remains in the solid state.

[0176] Keeping the molten sample 18 attached to the end 31 of the wire 3 further stabilizes the levitation of the molten droplet (sample) 18. Capillary forces contribute to allowing the molten sample 18 to remain suspended at the end 31 of the wire 3. Those skilled in the art will understand that maintaining the levitation of the molten sample 31 is only possible in the presence of the levitator 16.

[0177] The surface tension, or variations in surface tension, of the levitating molten sample 18 act as restoring forces on the levitating molten sample 18 when the latter tends, under the effects of destabilization, to shift from its equilibrium position.

[0178] The person skilled in the art will understand that obtaining a molten and levitating sample 18 is only possible in the presence of the levitator 16. Furthermore, in view of FIGURE 7A to 7C, the person skilled in the art will understand that such a geometry of a molten and levitating sample 31, in particular such spherical droplets 31, can only be obtained by the stabilization device 1 according to the invention.

[0179] Indeed, FIGURES 7A to 7C demonstrate that the stabilization device 1 according to the invention also makes it possible to counter additional instabilities, such as, for example, hot gas flows and geometric deformation of the sample.

[0180] Furthermore, the corolla observed in FIGURE 7C illustrates the temperature regularity of the molten sample 18 maintained in levitation, even on the periphery of the molten copper droplet 18. FIGURE 7C demonstrates the controlled confinement effect of the gases provided by the acoustic levitator 16 according to the invention, and in particular according to the non-limiting embodiment illustrated in FIGURE 4 and described in the present description.

[0181] FIGS. 7A, 7B and 7C also show the presence of a strong temperature gradient at the junction between droplet 18 and wire 3.

[0182] The preservation of the wire 3 in the solid state near its molten end 31 (in the liquid state) is permitted, according to the invention, by the presence of a high pressure zone of the acoustic field at the level of the distal end 31 junction of the wire 3 / molten droplet 18. This high pressure zone is provided by the use of the acoustic levitator 16, in particular by the acoustic levitator 16 according to the invention.

[0183] The acoustic field generated by the acoustic levitator 16, and in particular by the acoustic levitator 16 according to the invention, in addition to confining / maintaining the molten sample 18 in its levitation zone, also prevents the liquid metal of the molten sample 18 from rising up the wire 3 by capillarity. The coexistence of the molten sample 18 in contact with the solid end 31 of the wire 3 would not be possible without the presence of the levitation acoustic field.

[0184] A uniform distribution of the temperature in the molten spherical sample 18, close to that which would be obtained by levitation alone (without the connection between the distal end 31 of the wire 3 and the molten sample 18), is thus obtained thanks to the stabilization device 1 according to the invention.

[0185] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention.

[0186] Thus, it is possible to combine the different variants and improvements of the previously described embodiments.

[0187] In addition, the various features, forms, variations and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive.

Claims

CLAIMS 1. Device for stabilizing molten samples in a levitator, said device, said device comprises: - a hollow tube made of refractory material, called a refractory tube, forming a guide inside which a wire made of a metal or a metal alloy is intended to be placed, - a wire unwinding / winding mechanism located upstream of the refractory tube, relative to a direction connecting the unwinding / winding mechanism to the refractory tube, and arranged to translate the wire in the refractory tube, - an acoustic levitation device, called a levitator, comprising an opening or passage, connecting the exterior to the interior of the levitator, through which the wire and / or the hollow tube made of refractory material extends, - a control system arranged and / or programmed to control the winding / unwinding of the wire so as to control the position of a distal end of the wire outside the refractory tube and / or to position the distal end of the wire in the center of the levitator.

2. Device according to the preceding claim, in which the wire unwinding / winding mechanism and / or the refractory tube is arranged to keep the wire straight downstream of said unwinding / winding mechanism.

3. Device according to claim 1 or 2, wherein the wire unwinding / winding mechanism comprises at least one pair of rotating rollers arranged to grip the wire, said at least one pair of rotating rollers is arranged to unwind / wind the wire and / or to exert pressure on the wire.

4. Device according to the preceding claim, in which the unwinding / winding mechanism comprises a fixed element and a movable element, one of the rollers of the at least one pair of rollers is mounted on the fixed element and the other of the rollers of the at least one pair of rollers is mounted on the movable element, said movable element is arranged to translate perpendicular to an axis of revolution of the refractory tube.

5. Device according to claim 3 or 4, comprising a motor arranged to rotate one or each rotary roller of the at least one pair of rotary rollers.

6. Device according to any one of claims 3 to 5, in which an axis connecting a center of each of the two rotating rollers of the at least one pair of rollers is perpendicular to an axis of revolution of the refractory tube.

7. Device according to any one of claims 4 to 6, in which the wire unwinding / winding mechanism is arranged to modulate the pressure exerted by the rotating rollers on the wire.

8. Device according to any one of the preceding claims, comprising an additional hollow tube, called additional tube, forming a guide inside which the wire is intended to be arranged, the additional tube is arranged upstream of the wire unwinding / winding mechanism, relative to the direction connecting the unwinding / winding mechanism to the refractory tube, and an axis of revolution of the additional tube is mainly parallel to the axis of revolution of the refractory tube.

9. Device according to any one of the preceding claims, in which the levitator comprises a set of ultrasonic emitters, called transmitters, arranged to emit, each, an acoustic wave focused at the center of the levitator, the set of emitters is arranged to obtain standing acoustic waves whose intensity is maximum at the center of the levitator, the levitator comprises two facing domes; each dome comprises: - a first group of ultrasonic emitters, called transmitters, forming a cap extending between a pole and a stabilizer, - a second group of ultrasonic emitters, called emitters, forming the stabilizer and extending from the cap towards a plane of the levitator, called the median plane, which is perpendicular to the axis connecting the pole of each of the domes, called the axis of revolution, and which is located equidistant from the two poles;the stabilizers are arranged to form at least two pairs of emitters each comprising two radially opposite subgroups of emitters including a subgroup of emitters of the stabilizer of one dome and a subgroup of emitters of the stabilizer of the other dome, each subgroup of emitters comprises at least one emitter, the emitters of the cap of each of the domes are arranged to emit an acoustic wave having a first frequency fi and the emitters of the stabilizer of each of the domes are arranged to emit an acoustic wave having a frequency f2 different from fi, the two subgroups of emitters of one of the pairs of emitters are arranged to; emit acoustic waves whose phase differs from a phase of the acoustic waves emitted by the two subgroups of emitters of another of the pairs.

10. Device according to claim 9, comprising a control unit arranged so that the phase of the acoustic wave emitted by the at least two pairs of transmitters increases or decreases, by successive incrementation, from a given pair of transmitters to an adjacent pair of transmitters.

11. Device according to any one of claims 8 to 10, wherein the frequency fi is higher or lower than the frequency f2 by at least 5 kHz.

12. System for stabilizing and producing molten samples, said system, said system comprises: - the molten sample stabilization device according to any one of claims 1 to 11, - a system for melting a distal end of the wire intended to be melted.

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