Method for manufacturing metal powder and device for implementing the method

Abstract

The invention relates to a method for manufacturing a metal powder from a gas comprising a metal halide, as well as to a device for manufacturing a metal powder and to a system comprising such a device.

Description

[0001] Process for manufacturing metal powder and device for implementing the process.

[0002] Technical field of the invention

[0003] The present invention relates to a method for manufacturing a metal powder from a gas comprising a metal halide, as well as a device for manufacturing a metal powder and a system comprising such a device.

[0004] State of the art

[0005] Transition metals, for example molybdenum, rhenium, tungsten or iridium, can be used in many technical fields, for example in the medical field or in telecommunications.

[0006] It is therefore advantageous to have these metals available in powder form.

[0007] The powder can then be used as a raw material to manufacture more complex metal products.

[0008] For certain applications, for example in the medical or pharmaceutical fields, the metal powder must have a relatively high degree of purity, as well as controlled isotopy.

[0009] Document CN113020617A, for example, discloses a process for preparing an ultrafine refractory metal powder with a high level of purity. The process described in this document includes a step of heating and evaporating a metal halide in an evaporator, supplying the metal halide and hydrogen vapor to a reactor to obtain an ultrafine metal powder, a step of separating the superfine metal powder from the residual gas and heat-treating the powder, and a step of passivating the metal powder. However, such a process requires a preheating step for the metal halide and hydrogen vapor upstream of the reactor. Furthermore, the mixing of these gaseous phases takes place directly in the reactor, which is likely to limit the process yield and generate a powder with a less homogeneous particle size due to insufficient homogeneity of the gas mixture.This process is also geared more towards the production of nanoparticles than micrometer-sized particles. CN113020617 uses a filter for particle recovery, which has the drawback that the flow rate can vary as the filter fills. Document EP1579936 discloses a process for producing a metal powder, comprising a gas-phase reduction step of a metal chloride in the presence of a reducing gas, and a cooling step of the generated metal powder using a blown inert gas that creates a vortex flow. Such cooling in a vortex flow limits particle aggregation and adhesion to the internal walls of the metal powder production device.However, such a process involves the use of a complex device capable of implementing a cooling gas flow in parallel with the flows of gaseous metal chlorides and reducing gas, as well as a fluidic system configured to create a vortex.

[0010] Thus, there is a need to propose a metal powder manufacturing process that is both simple and quick to implement, and that allows the production of metal powder with a high yield, controlled particle size, and conservation of the isotopy of the metal atoms.

[0011] The present invention thus aims to remedy at least in part the aforementioned disadvantages, and to provide other advantages.

[0012] Description of the invention

[0013] To this end, a process for manufacturing a metallic powder of Me metal is proposed, according to a first aspect, comprising at least the following steps:

[0014] A step of supplying a first gas comprising a metal halide;

[0015] A step involving the supply of a second gas comprising dihydrogen;

[0016] A mixing step of the first gas and the second gas producing a gaseous mixture;

[0017] A heating step of a reaction chamber to a temperature, called the reaction temperature, between 950°C and 3000°C, for example between 950°C and 2500°C, and;

[0018] A step of pressurizing the reaction vessel to a pressure, called reaction pressure, between 200 mbar and 500 mbar;

[0019] A step of injecting the gas mixture into the reaction chamber maintained at the reaction temperature and reaction pressure;

[0020] A reaction step of the halide and dihydrogen of the gas mixture, in the reaction chamber maintained at the reaction pressure, and at the reaction temperature, producing the metallic powder of metal Me. In the context of this description, the powder refers, in a classical way, to a collection of particles, also referred to as "grains", each particle being formed of an agglomerate of crystallites.

[0021] This process allows for the preparation of a metal powder with controlled particle size and high chemical purity. Furthermore, this process does not affect the isotopic composition of the metal atoms. Therefore, the isotopic composition of the metal atom in the metal halide (gaseous precursor) will be preserved in the resulting metal powder.

[0022] Such a process is also simple and quick to implement.

[0023] Injecting the gas mixture at a temperature below the reaction temperature, for example at room temperature, makes it possible to avoid a preheating step of the gases before introduction into the chamber where the reaction takes place, the heating of the gases in the reaction chamber being sufficient to allow the production of the powder.

[0024] Pressurizing the reaction chamber allows the gas mixture to be injected directly into the reaction chamber at a temperature lower than the reaction temperature, for example, at ambient temperature. This reduces the risk of a metallic film forming along the mixer wall (described below).

[0025] Pressurizing the container where the reaction takes place also allows the reducing gas, for example dihydrogen, to be kept in excess in the container, promoting a relatively high yield.

[0026] Pressurizing the chamber also allows control of the average diameter of the metal powder produced, for example between 0.1 and 10 pm.

[0027] Finally, mixing the first and second gases before introducing them into the chamber prevents turbulence that could be caused by introducing two gas flows at different rates into the chamber of the device in which the reaction takes place, which could disrupt the reaction. In one embodiment, the process according to the invention includes a step of evacuating the chamber, for example to a pressure below 10⁻¹⁰ m³. 5 mbar, prior to the step of pressurizing the reaction vessel to a reaction pressure. In one implementation example, the process includes a step of gravity-depositing the metal powder into a catcher located downstream of the reaction vessel.

[0028] According to a preferred implementation example, the gravity deposition step includes a pressurization step of the recovery unit, at a pressure known as the recovery pressure, which is lower than the reaction pressure. Such a gravity deposition step allows for the simple recovery of the manufactured metal powder without the need for a filter that would require more maintenance.

[0029] In one example implementation, the metal halide of the first gas has the formula Me y X z in which Me is a transition metal, for example molybdenum, rhenium, tungsten or iridium; X is a halogen, for example fluorine, chlorine, bromine or iodine; y and z each being an integer greater than or equal to 1, y and z each being identified according to the chosen transition metal and halogen.

[0030] Examples of metal halidees covered by this formula include molybdenum hexafluoride (MoF6), molybdenum pentachloride (MoCl5), molybdenum trichloride (MoCl3), molybdenum pentabromide (MoBr5), molybdenum pentaiodide (Mol5), rhenium hexafluoride (ReF6), rhenium pentachloride (ReCl5), rhenium pentabromide (ReBr5), rhenium pentaiodide (Rel5), rhenium trichloride (ReCl3), tungsten hexafluoride (WF6), tungsten hexachloride (WCl6), tungsten tetrachloride (WCl4), tungsten hexabromide (WBr6), and tungsten hexaiodide (Wl6). iridium hexafluoride (I rF6), iridium trichloride (I rCI3), iridium tribromide (I rBr3), and iridium triiodide (lrl3).

[0031] For example, the metal halide of the first gas is molybdenum hexafluoride (MOF6).

[0032] In a preferred implementation example, the first gas comprises at least 99.9999 wt. % of the metal halide ("%wt." or "wt.%" denotes mass percentage).

[0033] The process produces a metal powder with a purity level comparable to that of the metal halide (gaseous precursor). Therefore, if the process uses a first gas with a high purity level, for example, a purity level of 6N (i.e., at least 99.999% pure), a metal powder with a corresponding purity level will be obtained. When a purity level of 6N is referred to for a chemical species in reference to a powder or gas in this description, it is understood that the gas or powder comprises at least 99.9999% wt. of the chemical species.

[0034] In one implementation example, the process includes a step to stop the injection of the gas mixture.

[0035] Stopping the gas mixing leads to the depletion of reactants and the cessation of the reaction. In one implementation example, the process includes a step of cooling the vessel from the reaction temperature to ambient temperature.

[0036] For example, the ambient temperature is lower than the reaction temperature. For example, the ambient temperature is between -30°C and +50°C.

[0037] For example, the chamber cooling stage takes place after the gravity deposition stage.

[0038] For example, such a cooling step of the enclosure takes place after the step of stopping the injection of the gas mixture.

[0039] In one implementation example, the process includes a step of returning the enclosure to ambient pressure from the reaction pressure.

[0040] For example, the stage of restoring ambient pressure to the enclosure takes place after the gravity deposition stage.

[0041] For example, such a step of restoring ambient pressure to the enclosure takes place after the step of stopping the injection of the gas mixture.

[0042] In one implementation example, a gas, for example nitrogen or hydrogen, for example a passivation gas, can be introduced into the enclosure during the enclosure cooling stage and during the enclosure return to ambient pressure stage.

[0043] Such cooling and re-pressurizing steps of the enclosure facilitate powder recovery.

[0044] In one implementation example, the process includes a step of passivating the metal powder.

[0045] This step is, for example, a prerequisite to a powder recovery step. For example, the passivation step of the metal powder involves bringing the said metal powder into contact with a passivation gas.

[0046] For example, the passivation gas may include oxygen, in a concentration of between 0.00001% wt. and 0.005% wt. For example, the passivation gas may include water vapor in a concentration of between 0.00001% wt. and 0.005% wt. ("wt.%" or "%wt." here denotes a mass percentage).

[0047] Such a passivation step makes it possible to generate an oxide film on the surface of the metal powder particles.

[0048] Such an oxide film helps to limit subsequent oxidation phenomena of the powder and thus promote its preservation and transformation if necessary.

[0049] In one example of implementation, the process includes:

[0050] a step of recovering a residual gas at the end of the reaction step; and a step of washing the recovered residual gas, the washing step comprising a substep of mixing the recovered residual gas with a washing solution having a pH between 7 and 14, and a substep of neutralizing at least one chemical species present in said recovered residual gas.

[0051] Such recovery and washing of residual gas makes it possible to limit, or even eliminate, the release of toxic elements into the environment.

[0052] In one implementation example, the first gas containing the metal halide is injected at an initial flow rate between 50 sccm and 150 sccm. (sccm stands for "standard cubic centimeters per minute," which corresponds to the mass flow rate of a gas (cm³) 3 / min) under standard temperature and pressure conditions, namely a standard temperature of 0°C and a standard pressure of 1 atm).

[0053] Such a flow rate of the first gas contributes to controlling the size of the particles generated, while giving the process a satisfactory yield, for example greater than or equal to 85%, and limiting losses in metal halides.

[0054] In one implementation example, the gas mixture obtained in the first gas and second gas mixing step comprises a volume ratio of dihydrogen to metal halide between 3 and 30, for example between 5 and 10.

[0055] Such a volume ratio of dihydrogen to metal halide contributes to controlling the size of the generated particles, while giving the process a satisfactory yield, for example, greater than or equal to 85%, and limiting losses of metal halides. The invention also provides, according to a second aspect, a metal powder comprising a metallic species Me, at a content between 99.9999 wt.% and 100 wt.% (mass percentage relative to the total mass of the powder).

[0056] Such a metal powder thus exhibits high purity, i.e., for example, at least "6N". Such a powder is therefore compatible, for example, with pharmaceutical and / or medical applications.

[0057] The metal powder can be made up of particles, preferably spherical particles.

[0058] In one implementation example, at least 95% of the metal powder particles have an average diameter between 0.4 pm and 5 pm.

[0059] The invention also proposes, according to a third aspect, a device for manufacturing a metallic powder.

[0060] The system includes, for example:

[0061] - an enclosure, comprising an inlet configured to inject a gaseous mixture into the enclosure, and at least one outlet configured to vent residual gas and metallic powder from the enclosure,

[0062] - a recovery unit comprising:

[0063] a fluidic communication input with at least one output of the enclosure,

[0064] at least one outlet configured to extract residual gas from the recuperator, and

[0065] a base configured to collect the obtained powder.

[0066] The recuperator may include at least one baffle, configured to slow down the residual gas and metal powder from the enclosure, allowing the metal powder to settle at the bottom of the recuperator.

[0067] Such a recuperator in a manufacturing device according to an embodiment of the invention makes it possible to recover the metal powder by gravity by reducing the speed of the gas flow.

[0068] For example, the collector has a side wall extending from the bottom of the collector and surrounding the bottom of the collector.

[0069] For example, the side wall of the receptacle surrounds the receptacle baffle. For example, the side wall of the receptacle includes holes forming at least one outlet of the receptacle.

[0070] For example, the recuperator has a pin in its center extending from the bottom of the recuperator to the outlet of the chamber. For example, the recuperator pin is configured to direct the flow of residual gas and powder between the recuperator baffle and the bottom of the recuperator.

[0071] The baffle of the recuperator is configured to divert the residual gas flow for extraction from the device.

[0072] The baffle thus helps to slow down the residual gas flow, promoting the deposition of the powder at the bottom of the recuperator.

[0073] For example, the baffle includes at least one tubular element surrounding the outlet of the enclosure.

[0074] Thus, during operation, the residual gas flow and powder flow inside the tubular element.

[0075] For example, the tubular element can be fixed to a platform defining the bottom of the enclosure.

[0076] For example, the tubular element is positioned at a distance from the bottom of the collector.

[0077] Thus, in operation, the residual gas flow, after passing through the inside of the tubular element, flows between the tubular element and the bottom of the recuperator.

[0078] In one embodiment example, at least one tubular element is a first tubular element, and the baffle includes a second tubular element, surrounding the first tubular element.

[0079] For example, the second tubular element can be fixed to the bottom of the recuperator. Thus, during operation, the residual gas flow, after passing between the first tubular element and the bottom of the recuperator, flows between the second element and the tray.

[0080] For example, the recuperator includes a pin extending from the bottom of the recuperator to the outlet of the chamber, with the pin centered on the axis of the chamber outlet. For example, the pin has a conical head, configured to direct the residual gas flow between the first tubular element and the bottom of the recuperator.

[0081] In the operating device, the recuperator is located below the reaction chamber, so that gravity allows the recovery of the metal powder while the speed of the gaseous flow carrying the powder decreases.

[0082] This limits the leakage of powders prepared by entrainment in the gas stream from the device, thereby optimizing the yield of a process implemented in such a device. Without departing from the scope of the invention, other recoverer geometries are possible, for example, with horizontal plates forming baffles.

[0083] Furthermore, such a device is simplified, in that it only includes a single means of injecting gases into the enclosure.

[0084] In one embodiment, the enclosure of the device for manufacturing a metal powder is made at least in part of a Me metal, or even at least 99 wt.% of Me metal, the Me metal being identical to the Me metal of the metal powder manufactured by the process described above.

[0085] In one embodiment, the collector of the device for manufacturing a metal powder is made at least partly of a Me metal, or even of at least 99 wt.% of Me metal, the Me metal being identical to the Me metal of the metal powder manufactured by the process described above.

[0086] For example, when a powder manufacturing device is used to manufacture molybdenum powder, the device's enclosure and collector are then made of molybdenum.

[0087] An enclosure and a collector of the same chemical nature as the metal powder to be manufactured makes it possible to maintain a level of purity of the powder to be produced and to limit a risk of contamination, for example by another chemical species during the manufacture of the powder.

[0088] Such a device makes it possible to control the flow of gas and particles in the enclosure and in the recuperator.

[0089] For example, an upper section of the enclosure, near the inlet, allows for gas expansion and flow stabilization. A second section of the enclosure, below the upper section, is the area where the reaction between the metal halide and dihydrogen takes place.

[0090] Finally, according to a fourth aspect, the invention proposes a system for manufacturing a metallic powder comprising:

[0091] - a device for manufacturing a metal powder as described above; - a chamber configured to be hermetically sealed, with the manufacturing device disposed within the chamber,

[0092] - a heating means, disposed in the chamber, and configured to heat said manufacturing device; - a pump, configured to modulate a pressure within at least the enclosure of the device; and

[0093] - a gas circuit comprising:

[0094] o at least one first supply line for a first gas, o a second supply line for a second gas,

[0095] o a mixer configured to mix the first gas and the second gas and provide a gaseous mixture, the mixer comprising:

[0096] o an initial fluidic communication entry with the first power supply line,

[0097] o a second fluidic communication input with the second power supply line,

[0098] o an output in fluidic communication with an input of the enclosure of the device for manufacturing a metal powder and configured to inject the gaseous mixture into the enclosure of the device.

[0099] Such a system allows control of pressure and temperature parameters inside the device enclosure.

[0100] For example, at least one output of the device is in fluidic communication with the chamber.

[0101] This allows for control of the yield of the process implemented in the system and for fine control of the parameters of the powders obtained.

[0102] Such a system allows two gases from two different lines to be mixed upstream of the chamber of the system comprising the device in which the reaction takes place, thus simplifying the assembly of such a system and limiting possible turbulence that could be caused by the introduction of two gas flows at different rates into the device in which the reaction takes place, which would be likely to disrupt the reaction.

[0103] In one embodiment, the heating means of the system is an induction coil, the induction coil being disposed within said chamber and around the manufacturing device.

[0104] In one embodiment example, the pump is configured to recover residual gas at the outlet of the device enclosure.

[0105] The residual gas can exit the metal powder manufacturing device through an outlet 17 of the recuperator, thus passing into the chamber. The residual gas then passes through an outlet of the chamber and is recovered by the pump. In one embodiment, the system includes a gas scrubber.

[0106] Such a gas scrubber makes it possible to limit, or even eliminate, the release of toxic elements into the environment.

[0107] For example, the gas scrubber is in fluidic communication with the pump.

[0108] For example, the gas scrubber is located downstream of the chamber.

[0109] For example, the gas scrubber is configured to neutralize at least one chemical species present in the residual gas.

[0110] For example, the gas scrubber is configured to produce a basic species shower enabling the neutralization of at least one chemical species present in the residual gas.

[0111] Brief description of the figures

[0112] The invention, according to an exemplary embodiment, will be better understood and its advantages will become clearer upon reading the following detailed description, given by way of example and in no way limiting, with reference to the attached drawings in which:

[0113] Figure 1 represents a device for manufacturing a metal powder according to an example of an embodiment of the invention, semi-assembled;

[0114] Figure 2 shows a device for manufacturing a metal powder according to an example of an embodiment of the invention, in cross-section;

[0115] Figure 3 schematically represents a system configured to implement the process according to an example of implementation of the invention;

[0116] Figure 4 illustrates a statistical distribution of particle size of a powder produced by the process according to an example of an implementation of the invention; and Figure 5 illustrates the shape of a sample of particles of a powder produced by the process according to an example of an implementation of the invention.

[0117] Detailed description

[0118] Method according to an example of implementation of the invention:

[0119] According to the invention, a metal powder is prepared from a metal halide.

[0120] A metallic powder here refers to a powder whose particles are at least partly composed of a metal Me. As described below, the powder obtained according to an example of an embodiment of the invention is composed of at least 99.9999 wt.% of the metal Me.

[0121] To achieve this, the chosen metal halide then contains the same metal Me. Gas supply and mixing steps

[0122] The process includes a step of supplying a first gas comprising a metal halide including the metal Me.

[0123] Such a metal halide in the first gas can have the formula Me y X z , in which Me can be a transition metal, for example molybdenum, rhenium, tungsten or iridium; X can be a halogen, for example fluorine, chlorine, bromine or iodine; y and z are each an integer equal to or greater than 1.

[0124] The first gas may comprise a metal halide at a high level of purity. For example, the first gas may comprise a metal halide with a content between 99.9999 wt. and 100 wt., which also corresponds to a degree of chemical purity of 6N.

[0125] As an example, the metal halide in the first gas could be molybdenum hexafluoride MoFe.

[0126] In one implementation example, the first gas including the metal halide is supplied at a first flow rate, the first flow rate being between 50 sccm and 150 sccm.

[0127] The process includes a step of supplying a second gas comprising dihydrogen.

[0128] In one implementation example, the second gas comprises at least 99.9999% dihydrogen, meaning that the second gas comprises nearly 100% dihydrogen, without taking into account any impurities present in negligible amounts.

[0129] In one implementation example, the second gas is supplied at a second flow rate.

[0130] For example, the second flow rate can be between 150 sccm and 4500 sccm.

[0131] The second flow rate can be chosen based on the first flow rate set for the first gas.

[0132] In one implementation example, the ratio between the flow rate of the second gas and the flow rate of the first gas is between 3 and 30.

[0133] The process also includes a step of mixing the first gas comprising metal halide and the second gas comprising dihydrogen, thus producing a gaseous mixture comprising metal halide and dihydrogen.

[0134] Heating and pressurization stages of a reaction vessel

[0135] The process includes a step of heating a reaction vessel. In one example implementation, the reaction vessel can be heated to a reaction temperature between 950°C and 3000°C, for example between 950°C and 2500°C.

[0136] According to one implementation example, the reaction temperature can be between 950°C and 2000°C, or even, for example, between 950°C and 1500°C.

[0137] The process also includes a step of pressurizing the reaction vessel.

[0138] In one implementation example, such a pressurization step can be carried out using a pumping system. In another implementation example, the reaction vessel can be brought to a reaction pressure between 200 mbar and 500 mbar.

[0139] In one implementation example, the heating and pressurization steps of the reaction vessel can take place consecutively.

[0140] In one example of implementation, the process according to the invention includes, prior to the step of pressurizing the enclosure to the reaction pressure, a step of evacuating the enclosure, for example to a pressure below 10' 5 mbar.

[0141] Injection and reaction steps

[0142] The process includes a step of injecting the gas mixture into the reaction chamber.

[0143] During the injection stage, the reaction chamber is maintained at the reaction temperature and reaction pressure.

[0144] The process includes a reaction step of the halide and dihydrogen from the gas mixture, producing the metal powder.

[0145] Such a step can take place in the reaction chamber, which is maintained at the reaction temperature and reaction pressure.

[0146] Such temperature and pressure conditions allow the reaction to take place and thus the production of the desired metal powder.

[0147] In one implementation example, maintaining the reaction temperature and reaction pressure in the reaction chamber during the injection of the gas mixture into the reaction chamber allows the reaction to take place.

[0148] In an alternative implementation example, the heating and pressurization steps of the reaction vessel can take place simultaneously. Gravity deposition steps

[0149] In one example implementation, the process includes a step of gravity deposition of the obtained metal powder, for example into a collector placed under the reaction chamber.

[0150] Such a gravity deposition step can take place concomitantly with the reaction step.

[0151] Such a gravity deposition step may include a sub-step of pressurizing the recuperator to a so-called "recovery" pressure.

[0152] The recovery pressure is then lower than the reaction pressure.

[0153] Such a pressure difference between the reaction pressure in the enclosure and the recovery pressure in the recuperator makes it possible to extract residual gas and metallic powder out of the enclosure and into the recuperator.

[0154] Cooling and return to ambient pressure stage

[0155] According to one embodiment, the process may include a step of cooling the enclosure from the reaction temperature to ambient temperature.

[0156] According to one embodiment, the process may include a step of reducing the reaction pressure to ambient pressure. During such a pressure reduction step, the atmosphere in the enclosure may include nitrogen; preferably, the atmosphere in the enclosure consists of nitrogen.

[0157] In one example of implementation, the process according to the invention may include controlling the chemical nature of the atmosphere within the enclosure during and / or after the reaction step.

[0158] For example, the atmosphere inside the chamber may be devoid of CO2 and / or C>2. The atmosphere within the reaction chamber may then contain nitrogen (N2). Alternatively, the atmosphere within the reaction chamber may contain a neutral gas, for example, argon (Ar).

[0159] Such an atmosphere helps to limit the oxidation of the metal powder obtained during the cooling stage.

[0160] Passivation step In one implementation example, the process includes a passivation step of the metal powder.

[0161] Such a passivation step makes it possible to generate an oxide film on the surface of the metal powder particles.

[0162] Such an oxide film limits subsequent oxidation of the powder, thus promoting its preservation and, if necessary, its processing. This passivation step results in the treated metal powder exhibiting reduced reactivity and improved stability.

[0163] The passivation step in the process may include a step of applying a passivation gas to the metal powder.

[0164] The passivation gas may include nitrogen, oxygen in a content between 0.00001 wt.% and 0.005 wt.% and water vapor in a content between 0.00001 wt.% and 0.001 wt.%.

[0165] For example, the passivation gas may include nitrogen, oxygen in a content between 0.00001 wt.% and 0.0001 wt.% and water vapor in a content between 0.00001 wt.% and 0.0003 wt.%.

[0166] Recovery stage

[0167] In one example of implementation, the process may include a step for recovering the metal powder.

[0168] Such a step can be implemented under a neutral atmosphere.

[0169] Such a step may include dismantling the device.

[0170] By "neutral atmosphere" we mean an atmosphere that will not have any effect on the powder, for example an atmosphere that will not induce its degradation or oxidation.

[0171] As an example, such an atmosphere may include nitrogen.

[0172] As an example, such an atmosphere may include a neutral gas, for example argon (Ar).

[0173] Preferably, such an atmosphere may not include dioxygen, water, or other organic solvents.

[0174] In one example of implementation, the process may include a step of recovering a residual gas at the end of the reaction step.

[0175] In one example implementation, the process may include a washing step. For example, the washing step includes a substep of mixing the recovered residual gas with a washing solution having a pH greater than 7 (basic washing solution), for example between 7 and 14.

[0176] For example, the washing step includes a substep of neutralizing at least one chemical species present in said recovered residual gas.

[0177] Such a basic washing solution could be a solution containing sodium hydroxide or alcoholic potassium hydroxide. A chemical species that can be neutralized could be hydrochloric acid (HCl), hydrogen fluoride (HF), and / or a metal halide that did not react during the reaction step of the process.

[0178] Device according to an example of an embodiment of the invention:

[0179] The process for manufacturing metal powder can be implemented in a device for manufacturing metal powder, for example as shown in Figures 1 and 2.

[0180] Figures 1 and 2 schematically illustrate in a semi-assembled manner a device 1 for manufacturing a metal powder, according to an example of an embodiment of the present invention, in overall view (figure 1) and in cross-section (figure 2).

[0181] Such a device for manufacturing metal powder includes the following:

[0182] - an enclosure 11 comprising an inlet 14 configured to inject a gaseous mixture into the enclosure, and an outlet 15 configured to evacuate residual gas and metallic powder from the enclosure,

[0183] - a recuperator 13 comprising an inlet 16 in fluidic communication with the outlet 15 of the reaction chamber,

[0184] - an outlet 17 configured to extract residual gas from the recuperator, and - a bottom 136 configured to collect the resulting powder,

[0185] the recuperator comprising a tubular element 132 forming a baffle, configured to slow down the residual gas and metallic powder coming from the enclosure.

[0186] Each element of the metal powder manufacturing device 1 has an axis of axial symmetry around the X axis.

[0187] The enclosure 11 of the metal powder manufacturing device 1 may include at least one cylindrical tube. In the present embodiment, the cylindrical tube comprises several sections: a first cylindrical tube 110, a second cylindrical tube 111, and a third cylindrical tube 112.

[0188] For example, the first cylindrical tube 110, the second cylindrical tube 111 and the third cylindrical tube 112 are coaxial.

[0189] Here, the second cylindrical tube is positioned between the first cylindrical tube and the third cylindrical tube.

[0190] The first cylindrical tube 110 and the second cylindrical tube 111 can be connected by a first insert 115.

[0191] The second cylindrical tube 111 and the third cylindrical tube 112 can be connected by a second insert 116.

[0192] Device 1 may include a plug 114 configured to obstruct an upper end of the enclosure 11. In the present embodiment, the plug 114 obstructs an upper end of the first cylindrical tube 110, thereby obstructing an upper section of the enclosure 11.

[0193] The plug 114 may include a first orifice constituting an inlet 14 of the enclosure 11.

[0194] The first orifice constituting an inlet 14 of the enclosure 11 can be configured to receive an injection lance.

[0195] In the present embodiment, a ring 113 can be placed on the plug 114 and configured to compensate for a difference in diameter between the first orifice constituting an inlet 14 of the enclosure 11 and an injection lance.

[0196] Device 1 may include a tray assembly 12 configured to obstruct a lower end of the enclosure 11. In the present embodiment, the tray assembly 12 obstructs a lower end of the third cylindrical tube 112, thus allowing to obstruct a lower section of the enclosure 11, located opposite the upper section obstructed by the plug 114.

[0197] The tray assembly 12 can include a base 121.

[0198] The base 121 of the tray assembly 12 may include in its center a second orifice, constituting an outlet 15 of the enclosure 11.

[0199] The base 121 of the tray assembly may include a wall, which may be flat or curved, capable of retaining the powder or guiding it towards the collector. The collector 13 may include an inlet 16 through which the residual gas and powder are introduced into the collector.

[0200] Input 16 of the receiver 13 is connected to output 15 of the enclosure 11.

[0201] The collector 13 may include a bottom 136 configured to retain the metal powder.

[0202] In the present embodiment, the base 136 includes a wall which can be flat or curved, capable of retaining the powder.

[0203] The recuperator 13 may include a side wall 135 extending from the bottom 136. The side wall 135 of the recuperator 13 includes at least one hole constituting an outlet 17 configured to extract the residual gas out of the device.

[0204] The recuperator 13 includes a baffle, configured to slow down the residual gas and metal powder from the enclosure, allowing the metal powder to be deposited in the bottom 136 of the recuperator 13, the baffle being surrounded by the side wall of the recuperator 13.

[0205] The baffle includes a first tubular element 122 surrounding the outlet 15 of the enclosure 11.

[0206] The tubular element 122 is fixed to the bottom 131 of the tray assembly 12 delimiting a bottom of the enclosure 11.

[0207] The tubular element 122 is positioned at a distance from the bottom 136 of the collector 13.

[0208] The baffle comprises a second tubular element 132 surrounding the first tubular element 122.

[0209] The second tubular element 132 is fixed to the bottom 136 of the collector 13.

[0210] The recuperator 13 includes a pin 131 which extends from the bottom of the recuperator to the outlet 15 of the enclosure 11.

[0211] Pawn 131 includes a head oriented towards the exit 15 of the enclosure 11.

[0212] The head 130 of the pin 131 is configured to direct the residual gas flow between the first tubular element 122 and the bottom 121 of the recuperator.

[0213] In the present embodiment, the head 130 of the pawn 131 has a conical shape.

[0214] However, other shapes are possible, such as an ogive or pyramid shape.

[0215] The pin 131 and its conical head 130 direct the residual gas flow between the first tubular element 122 and the bottom of the recuperator.

[0216] The pin 131 is centered on the axis of the outlet 15 of the enclosure 11. In an example embodiment in which the process according to the invention would be implemented in such a device for manufacturing a powder 1, the enclosure 11 of the device can be heated to a reaction temperature during the heating step, and pressurized to a reaction pressure during the pressurization step.

[0217] The injection of the gas mixture can be carried out in the enclosure 11 of the device 1, through the inlet 14 of the enclosure 11.

[0218] The reaction of the halide and dihydrogen from the gaseous mixture can then be carried out in the enclosure 11 of the device, the enclosure 11 being maintained at the reaction temperature and reaction pressure.

[0219] The residual gas and powder produced during the reaction of the metal halide and dihydrogen exits the enclosure 11 through outlet 15 and enters the recuperator 13 through inlet 16.

[0220] The path of the residual gas flow in the recuperator 13 is highlighted by arrow F in figures 1 and 2.

[0221] After passing between the first tubular element 122 and the bottom 136 of the recuperator, the residual gas flow flows between the first tubular element 122 and the second tubular element 132, then between the second tubular element 132 and the bottom 121 of the tray assembly 12.

[0222] Finally, the residual gas flow is extracted from the recuperator 13 through an outlet 17 formed by the holes in the side wall 135 of the recuperator.

[0223] The manufactured metal powder settled in the bottom 136 of the recuperator 13, due to the slowing of the gas flow caused by the baffle comprising the first tubular element 122 and the second tubular element 132.

[0224] According to one embodiment, all the parts of the device for manufacturing a metal powder 1 are made of a metal Me identical to the metal of the prepared metal powder. For example, when a process for preparing molybdenum powder is implemented in a device for manufacturing a metal powder 1, all the parts of the device are then made of molybdenum.

[0225] System according to an example of an embodiment of the invention:

[0226] The device for manufacturing a metal powder 1 can be included in a system 2, the system being able to implement the process. Figure 3 schematically illustrates such a system according to an example of an embodiment of the invention.

[0227] A system 2 may include a chamber 21 configured to be hermetically sealed. The chamber 21 may include an inlet 29 in a cover 27 and an outlet 30. The chamber 21 may also include a bottom 28 and side walls 31.

[0228] Chamber 21 of system 2 can include several functional zones, for example a preheating zone A, a heating zone B, and a pumping zone C.

[0229] The chamber 21 of system 2 may include a heating means 22 configured to heat the device for manufacturing a metal powder 1.

[0230] As an example, the heating means 22 includes an induction coil disposed within the chamber 21 and around the device for manufacturing a metal powder 1.

[0231] System 2 may include a pump 23 configured to modulate a pressure in chamber 21, the pump 23 being able to be connected to the outlet 30 of the chamber.

[0232] System 2 may include a device for manufacturing a metal powder 1 disposed inside chamber 21. For example, device 1 may be held in chamber 21 by means of a support 26. The inlet 15 of the enclosure 11 of device 1 may be in fluidic communication with the injection lance 25. The outlet 17 of the receptacle 13 of device 1 is in fluidic communication with a volume of chamber 21.

[0233] System 2 may include a gas circuit comprising:

[0234] o a first power supply line L1,

[0235] o a second L2 power supply line,

[0236] o a third supply line L3 in fluidic communication with an injection lance 25,

[0237] o a mixer 24 configured to mix a first gas supplied by the first supply line L1 and a second gas supplied by a supply line L2, and provide a gaseous mixture, the mixer 24 comprising:

[0238] o a first fluidic communication input with the first power supply line L1, o a second fluidic communication input with the second power supply line L2,

[0239] o an output in fluidic communication with the third supply line L3, the third supply line L3 also being in fluidic communication with an injection lance 25 configured to inject the gaseous mixture produced by the mixer 24 into a chamber 11 of a device for manufacturing a metal powder 1, through an inlet 14 of this chamber 11.

[0240] The gas circuit of system 2 may also include a fourth supply line L4, in fluidic communication with the injection lance 25.

[0241] When the metal powder manufacturing process is implemented in this system, the first feed line L1 can be configured to supply the first gas containing a metal halide, and the second feed line L2 can be configured to supply the second gas containing dihydrogen. The mixer 24 can be configured to mix the first gas containing a metal halide and the second gas containing dihydrogen, thus providing a gas mixture. The third feed line L3 of the gas circuit of system 2 is configured to carry the gas mixture from the mixer 24 to the metal powder manufacturing device I. The gas mixture can be injected into the reaction chamber 11 of the metal powder manufacturing device 1, through the inlet 14 of the chamber 11, by means of the injection lance 25.

[0242] The heating means 22 of system 2 allows the reaction chamber II of the device for manufacturing a metal powder 1 to be heated to a reaction temperature.

[0243] The pump 23 of system 2 allows the system 2 to be evacuated and, together with the gas circuit, the chamber 21 and therefore the enclosure 11 and the receiver 13 of the device for manufacturing a metal powder 1 to be brought to the reaction pressure.

[0244] The reaction step of the metal halide with dihydrogen can then take place in the reaction chamber 11 of the device for manufacturing a metal powder 1, maintained at the reaction temperature by the heating means 22 and maintained at the reaction pressure by the pump 23. During the reaction step, the metal powder and a residual gas are produced in the chamber 11 of the device for manufacturing a metal powder 1.

[0245] The metallic powder and residual gas can be extracted through an outlet 15 of the enclosure 11 to the recuperator 13 via an inlet 16.

[0246] The gravity deposition step can take place in the recuperator 13. The configuration of the first tubular element 122, forming a first baffle, and the second tubular element 132, forming a second baffle, within the recuperator 13, induces a slowing of the velocity of the residual gas carrying the metal powder. The metal powder then settles by gravity into the bottom 136 of the recuperator 13, and the residual gas is extracted from the recuperator 13 to chamber 21 of system 2 via at least one outlet 17. The residual gas can be extracted from chamber 21 of the system by pump 23.

[0247] After the injection of the gas mixture into the metal powder manufacturing device 1 has stopped, and during the cooling and re-entry to ambient pressure steps, a passivation gas can be supplied by the supply line L4 and injected into the enclosure 11 of the device, by the injection lance 25.

[0248] System 2 may also include a gas scrubber in fluidic communication with pump 23. Such a gas scrubber (not shown in the figures) may be disposed downstream of pump 23 and may be configured to neutralize at least one chemical species present in said residual gas.

[0249] The device 1 for manufacturing a metal powder can be easily extracted from system 2, for example by removing the cover 27 of the chamber 21. Extraction of the manufacturing device 1 from system 2 can be carried out when the chamber 21 is at ambient temperature after a cooling step of the chamber 21, and when the chamber 21 is at ambient pressure, after a step of restoring the chamber 21 to ambient pressure. The collector 13 of the device 1 for manufacturing a metal powder can then be opened to recover the metal powder.

[0250] Example: manufacturing molybdenum powder in a device according to an exemplary embodiment of the invention

[0251] A device for manufacturing a metal powder, as described above, made of molybdenum, is cleaned in an ultrasonic bath to remove any impurities. The device is then baked at 200°C for 8 hours, followed by degassing at 1600°C. The device is then placed in a chamber of a system as described above. The device is heated to a reaction temperature of 1000°C by an induction coil, and the system chamber is pressurized to a reaction pressure of 350 mbar. Molybdenum hexafluoride (MoFe) is supplied to a mixer at a flow rate of 100 sccm via a first feed line. Dihydrogen is supplied to the mixer at a flow rate of 600 sccm via a second feed line. The ratio of the dihydrogen flow rate to the MoFe flow rate is thus 6.The gas mixture produced by the mixer is introduced into the metal powder manufacturing device, which is maintained at a reaction temperature of 1000°C and a reaction pressure of 350 mbar for 4 hours. The introduction of MoFe into the device is stopped. To cool the device, the heating is stopped and the reaction pressure is maintained. During cooling, a stream of dihydrogen is introduced into the device. Once the device has reached ambient temperature, the dihydrogen stream is stopped, and the reaction vessel is purged of dihydrogen. The powder, in the recuperator, then undergoes a passivation step for 60 minutes using a stream of nitrogen introduced into the device, comprising 0.0003 wt.% water vapor and 0.0001 wt.% dioxygen. The device is then brought to ambient pressure and removed from the system.The device is then placed in a neutral atmosphere containing nitrogen but no oxygen or moisture. A 100 g sample of powder is collected, packaged, and can be analyzed.

[0252] The process achieved a yield of 90% (ratio between the mass of molybdenum powder recovered and the mass of molybdenum injected as MoFe via the first gas).

[0253] The powder obtained here has an average particle diameter of 1.5 pm.

[0254] The particle size distribution is relatively homogeneous, as shown in the graph presented in Figure 4.

[0255] The powder particles are relatively spherical and regular in appearance, as shown in the particle sample presented in Figure 5 (optical microscopy image). The powder particles in this sample have an average diameter of 1.11 pm.

[0256] Finally, in this example, the powder has a molybdenum purity of 99.9999% (6N).

Claims

DEMANDS 1. A process for manufacturing a metal powder of Me metal, the process comprising at least the following steps: A step of supplying a first gas comprising a metal halide including a metal Me; A step involving the supply of a second gas comprising dihydrogen; A mixing step of the first gas and the second gas producing a gaseous mixture; A heating step of a reaction chamber to a temperature, called the reaction temperature, between 950°C and 3000°C, and; A step of pressurizing the reaction vessel to a pressure, called reaction pressure, between 200 mbar and 500 mbar; A step of injecting the gas mixture into the reaction chamber maintained at the reaction temperature and reaction pressure; A reaction step of the halide and dihydrogen of the gas mixture, in the reaction chamber maintained at the reaction pressure, and at the reaction temperature, producing the metallic powder of Me metal.

2. A method according to claim 1, comprising a step of gravity deposition of the metal powder into a collector disposed downstream of the reaction chamber.

3. A method according to claim 2, wherein the gravity deposition step includes a step of pressurizing the recuperator to a pressure, referred to as the recovery pressure, the recovery pressure being lower than the reaction pressure.

4. A method according to any one of claims 2 or 3, comprising a step of cooling the enclosure from the reaction temperature to ambient temperature, and a step of returning the enclosure to ambient pressure, after the gravity deposition step.

5. A method according to any one of claims 1 to 4, wherein the metal halide has the formula Me y X z , where Me is molybdenum, of rhenium, tungsten or iridium; X is fluorine, chlorine, bromine or iodine; y and z are each an integer equal to or greater than 1.

6. A process according to claim 5, wherein the metal halide is molybdenum hexafluoride (MoFe).

7. A process according to any one of claims 1 to 6, comprising a step of passivating the metal powder, the passivation step comprising a step of applying a passivation gas to the metal powder, the passivation gas comprising nitrogen, oxygen in a content of between 0.00001 wt.% and 0.005 wt.% and water vapor in a content of between 0.00001 wt.% and 0.0003 wt.%.

8. A method according to any one of claims 1 to 7, comprising: a step of recovering a residual gas at the end of the reaction step; and a washing step, the washing step comprising a substep of mixing the recovered residual gas with a washing solution having a pH greater than 7, and a substep of neutralizing at least one chemical species present in said recovered residual gas.

9. A method according to any one of claims 1 to 8, wherein the first gas is injected at a first flow rate of between 50 sccm and 150 sccm.

10. A process according to any one of claims 1 to 9, wherein the gas mixture obtained in the step of mixing the first gas and the second gas comprises a volume ratio of dihydrogen to metal halide of between 3 and 30.

11. Metallic powder, characterized in that it comprises a metallic species Me, with a content of between 99.9999 wt.% and 100 wt.% (relative to the total mass of the powder).

12. Device (1) for manufacturing a metallic powder comprising - an enclosure (11) comprising an inlet (14) configured to inject a gaseous mixture into the enclosure (11), and at least one outlet (15) configured to vent residual gas and metallic powder out of the enclosure (11), and - a recuperator (13) comprising an inlet (16) in fluidic communication with at least one outlet (15) of the enclosure (11), at least one outlet (17) configured to extract the residual gas out of the recuperator (13), and a bottom (136) configured to collect the metal powder obtained, said recuperator (13) being configured to slow down the residual gas and the metal powder from the enclosure (11).

13. Device (1) according to claim 12, wherein the reclaimer (13) comprises at least one baffle.

14. Device (1) according to claim 13 in which the baffle comprises a first tubular element (122) and a second tubular element (132).

15. Device (1) according to any one of claims 12 to 14, wherein at least a part of the enclosure (11) and / or the collector (13) are made of a Me metal, the Me metal being identical to the metal of the prepared metal powder.

16. System (2) comprising: a device for manufacturing a metal powder (1) as defined in any one of claims 12 to 15, a chamber (21) configured to be hermetically sealed, the metal powder manufacturing device (1) being disposed in the chamber (21), a heating means (22) disposed in the chamber (21), and configured to heat said metal powder manufacturing device (1), a pump (23) configured to modulate a pressure in the enclosure (11) of the device (1), a gas circuit comprising: o at least one first supply line (L1) for a first gas, o a second supply line (L2) for a second gas, o a mixer (24) configured to mix the first gas and the second gas and provide a gaseous mixture, the mixer (24) comprising: ■ a first fluidic communication entry with the first supply line (L1), ■ a second fluidic communication input with the second supply line (L2), ■ an output in fluidic communication with an input (14) of the enclosure (11) of the device for manufacturing a metal powder (1) by means of an injection lance (25) configured to inject the gas mixture into the enclosure (11) of the device for manufacturing a powder (1).

17. System (2) according to claim 16, wherein the heating means (22) comprises an induction coil, the induction coil being disposed within the chamber (21) and around the device for manufacturing a metal powder (1).

18. System 2 according to any one of claims 16 or 17, wherein the pump (23) is configured to recover residual gas at an outlet (30) of the chamber (21).

19. System (2) according to claim 18, comprising a gas scrubber in fluidic communication with said pump (23) recovering the residual gas, downstream of the chamber (21), configured to neutralize at least one chemical species present in said residual gas.

Images