WO2020050202A1 - 微粒子の製造装置および微粒子の製造方法 - Google Patents
微粒子の製造装置および微粒子の製造方法 Download PDFInfo
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- WO2020050202A1 WO2020050202A1 PCT/JP2019/034379 JP2019034379W WO2020050202A1 WO 2020050202 A1 WO2020050202 A1 WO 2020050202A1 JP 2019034379 W JP2019034379 W JP 2019034379W WO 2020050202 A1 WO2020050202 A1 WO 2020050202A1
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- C01B33/027—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material
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- B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
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- B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
- B01J2/02—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops
- B01J2/04—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops in a gaseous medium
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- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/003—Apparatus, e.g. furnaces
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- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
- B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
- B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
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- B22F9/00—Making metallic powder or suspensions thereof
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- B22F9/14—Making metallic powder or suspensions thereof using physical processes using electric discharge
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/02—Silicon
- C01B33/021—Preparation
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- H—ELECTRICITY
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- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H1/00—Generating plasma; Handling plasma
- H05H1/24—Generating plasma
- H05H1/26—Plasma torches
- H05H1/30—Plasma torches using applied electromagnetic fields, e.g. high frequency or microwave energy
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- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H1/00—Generating plasma; Handling plasma
- H05H1/24—Generating plasma
- H05H1/26—Plasma torches
- H05H1/32—Plasma torches using an arc
- H05H1/42—Plasma torches using an arc with provisions for introducing materials into the plasma, e.g. powder, liquid
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H1/00—Generating plasma; Handling plasma
- H05H1/24—Generating plasma
- H05H1/46—Generating plasma using applied electromagnetic fields, e.g. high frequency or microwave energy
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
- B01J2219/0869—Feeding or evacuating the reactor
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- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
- B01J2219/0873—Materials to be treated
- B01J2219/0875—Gas
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
- B01J2219/0873—Materials to be treated
- B01J2219/0881—Two or more materials
- B01J2219/089—Liquid-solid
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
- B01J2219/0894—Processes carried out in the presence of a plasma
- B01J2219/0898—Hot plasma
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- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
- B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
- B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
- B22F2009/086—Cooling after atomisation
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- B22F2202/00—Treatment under specific physical conditions
- B22F2202/13—Use of plasma
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
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- B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H2245/00—Applications of plasma devices
- H05H2245/50—Production of nanostructures
Definitions
- the present invention relates to an apparatus for producing fine particles using a thermal plasma flame and a method for producing fine particles, and in particular, an apparatus and a method for producing fine particles for producing fine particles, which time-modulate and supply a quenching gas used for cooling the thermal plasma flame, and the fine particles And a method for producing the same.
- fine particles such as silicon fine particles, oxide fine particles, nitride fine particles, and carbide fine particles are used in various fields.
- One of the methods for producing such fine particles is a gas phase method.
- the gas phase method includes a chemical method of chemically reacting various gases at a high temperature, and a physical method of irradiating a beam such as an electron beam or a laser to decompose a substance and evaporate the substance to generate fine particles. .
- the thermal plasma method is a method in which raw materials are instantaneously evaporated in a thermal plasma flame, and then the evaporated material is rapidly cooled and solidified to produce fine particles. According to the thermal plasma method, it has many advantages such as cleanness, high productivity, high heat capacity at high temperature, compatibility with high melting point materials, and relatively easy compounding compared to other gas phase methods. Having. Therefore, the thermal plasma method is actively used as a method for producing fine particles.
- Patent Document 1 discloses a method for producing titanium carbide fine particles.
- a step of dispersing titanium or titanium oxide powder with a carrier gas and supplying the titanium or titanium oxide powder into a thermal plasma flame, and a step of disposing a cooling gas and carbon A step of supplying a reactive gas as a source to generate titanium carbide fine particles, and changing the supply amount of the reactive gas to change the oxygen content of the generated titanium carbide fine particles.
- Patent Document 1 discloses that a powder of titanium or titanium oxide is dispersed in a liquid substance containing carbon as a carbon source to form a slurry, and the slurry is formed into droplets by a carrier gas to form a slurry in a hot plasma flame.
- the method includes a step of supplying the slurry, controlling the feed amount of the slurry to be constant, changing the flow rate of the carrier gas when charging the slurry, and changing the oxygen content of the generated titanium carbide fine particles. Have been.
- Patent Document 1 As a method for producing fine particles, as described in Patent Document 1 described above, titanium or titanium oxide powder is dispersed in a carrier gas and supplied into a thermal plasma flame, and titanium or titanium oxide powder is converted into a slurry. It has been conventionally known that a slurry is formed into droplets by a carrier gas and supplied into a thermal plasma flame. Although the production method described in Patent Document 1 can produce nano-sized fine particles, fine particles having a smaller size are required at present, and this requirement cannot be sufficiently satisfied.
- An object of the present invention is to provide a fine particle manufacturing apparatus and a fine particle manufacturing method for manufacturing smaller fine particles.
- the present invention is an apparatus for producing fine particles, and a raw material supply unit for supplying raw materials for producing fine particles into a thermal plasma flame, wherein the thermal plasma flame is generated inside,
- a plasma torch that evaporates the raw material supplied by the raw material supply unit with the thermal plasma flame to form a mixture in a gaseous state;
- a plasma generation unit that generates the thermal plasma flame inside the plasma torch;
- a gas supply unit for supplying a quenching gas to the plasma flame, wherein the gas supply unit provides a device for producing fine particles, wherein the supply amount of the quenching gas is time-modulated and supplied.
- the raw material supply unit supplies the raw material into the thermal plasma flame by time-modulating the supply amount of the raw material into the thermal plasma flame. Further, the plasma generation unit generates a modulated induction thermal plasma flame in which a temperature state is time-modulated as the thermal plasma flame, and periodically sets the modulated induction thermal plasma flame to a high temperature state and a temperature higher than the high temperature state. Is preferably low.
- the gas supply unit increases a supply amount of the quenched gas when the modulated induction thermal plasma flame is in the low temperature state. It is preferable that the material supply unit increases the supply amount of the material when the modulated induction thermal plasma flame is in the high temperature state. It is preferable that the raw material supply unit supplies the raw material into the thermal plasma flame in a state of being dispersed in the form of particles. It is preferable that the raw material supply unit disperses the raw material in a liquid to form a slurry, converts the slurry into droplets, and supplies the droplets into the thermal plasma flame.
- the present invention is also a method for producing fine particles, wherein a first step of supplying a raw material for producing fine particles to a thermal plasma flame, and evaporating the raw material with the thermal plasma flame to form a mixture in a gas phase, And a second step of supplying a quenched gas to the thermal plasma flame.
- a method of producing fine particles is provided, wherein the supply amount of the quenched gas is time-modulated and supplied.
- the thermal plasma flame is a modulation induction thermal plasma flame in which a temperature state is time-modulated and periodically changed to a high temperature state and a low temperature state lower in temperature than the high temperature state.
- the supply amount of the quenching gas is increased when the modulation induction thermal plasma flame is in the low temperature state.
- the raw material is supplied into the thermal plasma flame in a state of being dispersed in the form of particles.
- the raw material is dispersed in a liquid to form a slurry, and the slurry is formed into droplets and supplied into the thermal plasma flame.
- FIG. 4 is an explanatory diagram of a time change of a coil current at the time of pulse modulation.
- A is a graph showing a pulse control signal for modulating a coil current
- (b) is a graph showing a valve opening / closing timing
- (c) is a graph showing a supply of a raw material.
- FIG. 3 is a schematic perspective view showing a model used for numerical calculation.
- (A)-(d) is a schematic diagram showing a temperature distribution when the quenched gas is time-modulated.
- (A)-(d) is a schematic diagram showing a temperature distribution when time modulation is not performed. It is a graph which shows distribution of time average temperature in the central axis of a model. 6 is a graph showing a time change of a temperature distribution on a central axis of the model.
- (A)-(h) is a schematic diagram showing a temperature distribution when the flow rates of the thermal plasma flame and the quenched gas are time-modulated.
- (A)-(h) is a schematic diagram showing the trajectory of particles when the flow rates of the thermal plasma flame and the quenched gas are time-modulated.
- FIG. 1 is a schematic view illustrating an example of a fine particle manufacturing apparatus according to an embodiment of the present invention.
- the fine particle manufacturing apparatus 10 shown in FIG. 1 is for manufacturing nano-sized fine particles using raw materials for manufacturing fine particles.
- powder is used as a raw material for producing fine particles.
- the type of the manufacturing apparatus 10 is not particularly limited as long as the fine particles are fine particles.
- fine particles other than metal fine particles may be used, such as oxide fine particles, nitride fine particles, carbide fine particles, Fine particles such as oxynitride fine particles can be produced.
- the manufacturing apparatus 10 includes a raw material supply unit 12, a plasma torch 14, a chamber 16, a recovery unit 18, a plasma gas supply unit 20, a plasma generation unit 21, a gas supply unit 22, and a control unit 24. .
- the raw material supply unit 12 is connected to a plasma torch 14 via a hollow supply pipe 13. Further, an intermittent supply unit 15 may be provided in the supply pipe 13 between the raw material supply unit 12 and the plasma torch 14 as described later. In the manufacturing apparatus 10, the intermittent supply unit 15 is not an essential component, but it is more preferable to provide the intermittent supply unit 15.
- a chamber 16 is provided below the plasma torch 14, and a collection unit 18 is provided in the chamber 16.
- the plasma generator 21 is connected to the plasma torch 14, and generates a thermal plasma flame 100 inside the plasma torch 14 by the plasma generator 21 as described later.
- the raw material supply unit 12 supplies a raw material for producing fine particles into a thermal plasma flame 100 generated inside the plasma torch 14.
- the raw material supply unit 12 is not particularly limited as long as the raw material can be supplied into the thermal plasma flame 100.
- the raw material supply unit 12 supplies the raw material into the thermal plasma flame 100 in a state of being dispersed in the form of particles. Is converted into a slurry, and the slurry is supplied into the thermal plasma flame 100 in the form of droplets.
- the raw material supply unit 12 quantitatively supplies the raw material of the powder into the thermal plasma flame 100 inside the plasma torch 14 while maintaining the raw material in a dispersed state.
- the material supply unit 12 having such a function for example, an apparatus disclosed in Japanese Patent No. 3217415 and Japanese Patent Application Laid-Open No. 2007-138287 can be used.
- the raw material supply unit 12 includes, for example, a storage tank (not shown) for storing raw material powder, a screw feeder (not shown) for quantitatively conveying raw material powder, and a raw material powder conveyed by the screw feeder. Has a dispersion portion (not shown) for dispersing it into particles before it is finally sprayed, and a carrier gas supply source (not shown).
- the raw material powder is supplied to the thermal plasma flame 100 in the plasma torch 14 through the supply pipe 13 together with the carrier gas that has been extruded from the carrier gas supply source and applied with pressure.
- the raw material supply unit 12 can prevent the raw material powder from aggregating, and can disperse the raw material powder into the plasma torch 14 in a state of being dispersed in the form of particles while maintaining the dispersed state.
- the configuration is not particularly limited.
- the carrier gas for example, an inert gas such as an argon gas (Ar gas) or a nitrogen gas is used.
- the raw material supply unit 12 for supplying the raw material powder in the form of a slurry for example, the one disclosed in JP-A-2011-213524 can be used.
- the raw material supply unit 12 includes a container (not shown) for storing a slurry (not shown) in which the raw material powder is dispersed in a liquid such as water, and a stirrer (not shown) for stirring the slurry in the container. And a pump (not shown) for applying high pressure to the slurry through the supply pipe 13 and supplying the slurry into the plasma torch 14, and supplying a spray gas for forming the slurry into droplets and supplying the slurry into the plasma torch 14.
- Spray gas supply source (not shown).
- the spray gas supply source corresponds to a carrier gas supply source.
- the spray gas is also called a carrier gas.
- the raw material powder is dispersed in a liquid such as water to form a slurry.
- the mixing ratio of the raw material powder and water in the slurry is not particularly limited, and is, for example, 5: 5 (50%: 50%) by mass.
- the spray gas that is extruded from the spray gas supply source and is applied with pressure through the supply pipe 13 together with the slurry. It is supplied into the thermal plasma flame 100 in the plasma torch 14.
- the supply pipe 13 has a two-fluid nozzle mechanism for spraying the slurry into the thermal plasma flame 100 in the plasma torch and turning the slurry into droplets. Spray. That is, the slurry can be formed into droplets.
- an inert gas such as an argon gas (Ar gas) or a nitrogen gas is used similarly to the above-described carrier gas.
- the two-fluid nozzle mechanism can apply a high pressure to the slurry and spray the slurry with a spray gas (carrier gas) that is a gas, and is used as one method for forming the slurry into droplets.
- a spray gas carrier gas
- the present invention is not limited to the two-fluid nozzle mechanism described above, and a one-fluid nozzle mechanism may be used.
- a method of dropping a slurry on a rotating disk at a constant speed to form droplets by centrifugal force (forming droplets), or applying a high voltage to the slurry surface to form a liquid A method of forming droplets (generating droplets) is exemplified.
- the plasma torch 14 a thermal plasma flame 100 is generated inside, and the raw material supplied by the raw material supply unit 12 is evaporated by the thermal plasma flame 100 to form a mixture 45 in a gaseous state.
- the plasma torch 14 includes a quartz tube 14a and a high-frequency oscillation coil 14b provided on the outer surface of the quartz tube 14a and surrounding the outside of the plasma torch 14.
- a supply port 14c into which the supply pipe 13 is inserted is provided at the center of the upper part of the plasma torch 14, and a plasma gas supply port 14d is formed at a peripheral portion thereof (on the same circumference).
- a powdery raw material and a carrier gas such as an argon gas or a hydrogen gas are supplied into the plasma torch 14.
- the plasma gas supply unit 20 is connected to the plasma gas supply port 14d by, for example, a pipe (not shown).
- the plasma gas supply unit 20 supplies a plasma gas into the plasma torch 14 through a plasma gas supply port 14d.
- the plasma gas for example, an argon gas and a hydrogen gas are used alone or in an appropriate combination.
- the outside of the quartz tube 14a of the plasma torch 14 is surrounded by a quartz tube 14e formed concentrically, and cooling water 14f is circulated between the quartz tubes 14a and 14e to cool the quartz tube 14a with water.
- the quartz tube 14a is prevented from becoming too hot due to the thermal plasma flame 100 generated in the plasma torch 14.
- the plasma generator 21 has a high-frequency power supply (not shown), and applies a high-frequency current to the high-frequency oscillation coil 14b.
- a high-frequency current is applied to the high-frequency oscillation coil 14b, a thermal plasma flame 100 is generated inside the plasma torch 14.
- the pressure atmosphere in the plasma torch 14 is appropriately determined according to the production conditions of the fine particles, and is, for example, equal to or lower than the atmospheric pressure.
- the atmosphere under the atmospheric pressure is not particularly limited, but may be, for example, 5 Torr (666.5 Pa) to 750 Torr (99.975 kPa).
- the chamber 16 has an upstream chamber 16a mounted coaxially with the plasma torch 14 from the side closer to the plasma torch 14. Further, a downstream chamber 16b is provided perpendicularly to the upstream chamber 16a, and further downstream is provided a recovery unit 18 provided with a desired filter 18a for collecting fine particles. In the manufacturing apparatus 10, the collection place of the fine particles is, for example, the filter 18a.
- the gas supply unit 22 is connected to the chamber 16. Fine particles (not shown) of a material corresponding to the raw material are generated in the chamber 16 by the quenching gas supplied from the gas supply unit 22.
- the chamber 16 functions as a cooling tank.
- the collection unit 18 includes a collection chamber provided with a filter 18a, and a vacuum pump 18b connected via a pipe provided below the collection chamber.
- the fine particles sent from the chamber 16 are sucked by the above-described vacuum pump 18b, so that the fine particles are drawn into the collection chamber and collected while remaining on the surface of the filter 18a.
- the gas supply unit 22 supplies a quench gas to the thermal plasma flame 100 in the chamber 16.
- the quenching gas functions as a cooling gas.
- the gas supply unit 22 has a gas supply source (not shown) in which gas is stored, and a pressure applying unit (not shown) such as a compressor or a blower that applies an extrusion pressure to the quenched gas supplied into the chamber 16. . Further, an adjustment valve (not shown) for controlling the gas supply amount from the gas supply source is provided.
- the gas supply source one according to the composition of the quenched gas is used, and the type of gas is not limited to one type.
- the quenched gas is a mixed gas, a plurality of gas supply sources are prepared.
- the quenched gas is not particularly limited as long as it exhibits a cooling function.
- the quenching gas for example, an inert gas such as an argon gas, a nitrogen gas, and a helium gas that does not react with the raw material is used.
- the quenched gas may further contain hydrogen gas.
- the quenched gas may contain a reactive gas that reacts with the raw material. Examples of the reactive gas include various hydrocarbon gases having 4 or less carbon atoms such as methane, ethane, propane, butane, acetylene, ethylene, propylene, and butene.
- the gas supply unit 22 is directed, for example, toward the tail 100b (see FIG. 2) of the thermal plasma flame 100, that is, toward the end of the thermal plasma flame 100 opposite to the plasma gas supply port 14d, that is, toward the terminal end of the thermal plasma flame 100.
- the quenching gas is supplied at an angle of 45 °
- the quenching gas is supplied from above to below along the inner wall of the chamber 16.
- it is not limited to supplying the quenching gas to the end portion of the thermal plasma flame 100.
- the quenched gas supplied from the gas supply unit 22 into the chamber 16 rapidly cools the mixture in the gaseous phase by the thermal plasma flame 100 to obtain fine particles of a material corresponding to the raw material.
- the above-mentioned quenched gas has an additional action such as contributing to the classification of fine particles.
- the fine particles collide with each other and form an aggregate, which causes a non-uniform particle diameter, which causes quality deterioration.
- the quenching gas dilutes the fine particles, thereby preventing the fine particles from colliding and aggregating.
- the quenched gas along the inner wall surface of the chamber 16 in the process of collecting the fine particles, the fine particles are prevented from adhering to the inner wall of the chamber 16, and the yield of the generated fine particles is improved.
- the gas supply unit 22 supplies the quenched gas to the thermal plasma flame 100 as described above.
- the supply amount of the quenched gas is not constant, but is time-modulated to supply the quenched gas.
- the time change of the supply amount is not particularly limited, and may be a sine wave, a triangle wave, a square wave, or a sawtooth wave.
- the supply amount from the gas supply source is made constant, and the supply amount is time-modulated using, for example, a ball valve as an adjustment valve.
- the method of supplying the quench gas to the thermal plasma flame 100 of the gas supply unit 22 is not particularly limited, and the quench gas may be supplied from one direction. Further, the quenching gas may be supplied from a plurality of directions surrounding the periphery of the thermal plasma flame 100. In this case, a plurality of quenching gas supply ports are provided on the outer peripheral surface of the chamber 16 along the circumferential direction, for example, at equal intervals, but are not limited to equal intervals.
- the supply timing is not particularly limited, and the quenched gas is supplied in a synchronized manner from a plurality of directions. Alternatively, for example, the quenching gas may be supplied in a clockwise or counterclockwise order. In this case, an air current such as a swirling flow is generated in the chamber 16 by the quenching gas.
- the quenched gas may be supplied at random without determining the supply order.
- the raw material supply unit 12 supplies the raw material to the thermal plasma flame 100 as described above, supplies the raw material in a predetermined amount, and supplies a constant amount of the raw material regardless of time. .
- the raw material supply unit 12 may supply the raw material into the thermal plasma flame 100 by time-modulating the supply amount of the raw material into the thermal plasma flame 100. As a result, even if the thermal plasma flame 100 does not change, it changes with time.
- the supply pipe 13 is provided with an intermittent supply unit 15.
- the intermittent supply unit 15 supplies the raw material into the chamber 16 with time modulation.
- the change in the supply amount of the raw material is not particularly limited, and may be a sine wave, a triangle wave, a square wave, or a sawtooth wave.
- the time modulation it is preferable that the supply of the quenched gas and the supply of the raw material have the same time change expressed by a function. This makes it easy to match the timing of the supply of the quenched gas with the supply of the raw material.
- the intermittent supply unit 15 modulates the supply amount of the raw material over time using, for example, a solenoid valve (electromagnetic valve) connected to the supply pipe 13.
- the opening and closing of the solenoid valve is controlled by the control unit 24.
- a solenoid valve instead of a solenoid valve, a ball valve may be used. Also in this case, the opening and closing of the ball valve is controlled by the control unit 24.
- the control unit 24 modulates the supply amount in a time-varying manner, for example, in a pattern in which the supply amount of the raw material is reduced when the supply amount of the quenched gas is large, and the supply amount of the raw material is increased when the supply amount of the quenched gas is small. I do. Thereby, smaller fine particles can be manufactured.
- the manufacturing apparatus 10 can supply the quenched gas in a time-modulated manner, whereby the thermal plasma flame can be further cooled, and a low temperature state can be created. For this reason, smaller fine particles can be manufactured. Furthermore, the manufacturing apparatus 10 can also time-modulate the supply of the raw material. In this case, by further time-modulating the supply of the raw material together with the time modulation of the quenched gas, it is possible to produce finer particles. Note that the timing of the supply of the quenched gas and the supply of the raw material is preferably such that the supply of the raw material is increased when the supply amount of the quenched gas is small.
- a method for producing fine particles using the above-described production apparatus 10 will be described using metal fine particles as an example.
- a raw material powder of metal fine particles for example, Si powder having an average particle diameter of 10 ⁇ m or less is supplied to the raw material supply unit 12.
- a high-frequency voltage is applied to the high-frequency oscillation coil 14b (see FIG. 2) using, for example, argon gas and hydrogen gas as the plasma gas, and a thermal plasma flame 100 is generated in the plasma torch 14.
- a mixed gas of, for example, argon gas and methane gas is supplied from the gas supply unit 22 to the tail part 100b (see FIG. 2) of the thermal plasma flame 100, that is, the end part of the thermal plasma flame 100, as a quenching gas.
- Si powder is gas-transported using, for example, argon gas as a carrier gas, and supplied into the thermal plasma flame 100 in the plasma torch 14 through the supply pipe 13 (first step).
- the supplied Si powder evaporates in the thermal plasma flame 100 to become a gas-phase mixture 45 (see FIG. 2).
- the quenched gas is time-modulated, that is, the supply amount is periodically changed, and the quenched gas is supplied to the thermal plasma flame 100 (second step).
- the thermal plasma flame 100 is rapidly cooled to generate Si fine particles (metal fine particles). At this time, a region where the temperature is low is generated in the chamber 16 and smaller Si fine particles are obtained.
- the Si fine particles obtained in the chamber 16 are collected on the filter 18a of the collection unit 18 by the negative pressure (suction force) from the collection unit 18 by the vacuum pump 18b.
- the quenched gas is time-modulated, but the supply of the raw material may be further time-modulated. In this case, it is preferable to increase the supply of the raw material when the supply amount of the quenched gas is small.
- the supply timing of the quenched gas and the supply timing of the raw material are adjusted by the control unit 24.
- FIG. 3 is a schematic diagram showing another example of the apparatus for producing fine particles according to the embodiment of the present invention
- FIG. 4 is an explanatory diagram showing a time change of a coil current at the time of pulse modulation.
- the apparatus 10a for producing fine particles shown in FIG. 3 hereinafter simply referred to as the apparatus 10a
- the same components as those in the apparatus 10 shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.
- the manufacturing apparatus 10a shown in FIG. 3 is different from the manufacturing apparatus 10 shown in FIG. 1 in that a high frequency modulation induction thermal plasma generating section 26 is provided instead of the plasma generating section 21 (see FIG. 1). Is the same as that of the manufacturing apparatus 10 shown in FIG.
- the raw material supply unit 12 is connected to the intermittent supply unit 15, similarly to the manufacturing apparatus 10 shown in FIG.
- the intermittent supply part 15 and the plasma torch 14 are connected via a hollow supply pipe 13.
- the high-frequency modulation induction thermal plasma generator 26 is provided instead of the plasma generator 21 (see FIG. 1).
- the high-frequency modulation induction thermal plasma generating section 26 generates a thermal plasma flame 100 inside the plasma torch 14 and time-modulates the temperature state of the thermal plasma flame 100 so that the temperature state of the thermal plasma flame 100 is periodically changed.
- Modulated induction thermal plasma means that the thermal plasma flame is periodically brought to a high temperature state at predetermined time intervals and a low temperature state lower than the high temperature state, that is, a temperature state of the thermal plasma flame is time-modulated. Called fire.
- the raw material supply unit 12 is connected to a valve 30c of the intermittent supply unit 15 provided above the plasma torch 14.
- the high-frequency modulation induction thermal plasma generator 26 supplies a high-frequency current for generating the thermal plasma flame 100 to the high-frequency oscillation coil 14b (see FIG. 2) and supplies the high-frequency current to the high-frequency oscillation coil 14b at a predetermined time interval. Can be amplitude modulated.
- a high-frequency current supplied to the high-frequency oscillation coil 14b to generate the thermal plasma flame 100 is referred to as a coil current.
- the high-frequency modulation induction thermal plasma generator 26 has a high-frequency inverter power supply 28a, an impedance matching circuit 28b, a pulse signal generator 28c, and an FET gate signal circuit 28d.
- the MOSFET inverter power supply constituting the high-frequency inverter power supply 28a has a function of modulating the amplitude of the current, and can modulate the amplitude of the coil current.
- the high-frequency inverter power supply 28a has, for example, a rectifier circuit and a MOSFET inverter circuit.
- the rectifier circuit uses, for example, a three-phase AC as an input power supply. After performing AC-DC conversion by a three-phase full-wave rectifier circuit, an IGBT (insulated gate bipolar transistor) is used. The output voltage value is changed by the DC-DC converter.
- the MOSFET inverter circuit is connected to a rectifier circuit, and converts DC obtained by the rectifier circuit into AC. Thereby, the inverter output, that is, the coil current is amplitude-modulated (AM-modulated).
- the high frequency inverter power supply 28a is connected to an impedance matching circuit 28b on the output side.
- the impedance matching circuit 28b is configured by a series resonance circuit including a capacitor and a resonance coil, and performs impedance matching such that the resonance frequency of the load impedance including the plasma load falls within the driving frequency range of the high-frequency inverter power supply 28a. Things.
- the pulse signal generator 28c generates a pulse control signal for applying rectangular wave modulation to the amplitude of the coil current for maintaining the high-frequency modulated induction thermal plasma.
- the FET gate signal circuit 28d supplies a modulation signal based on the pulse control signal generated by the pulse signal generator 28c to the gate of the MOSFET of the MOSFET inverter circuit of the high-frequency inverter power supply 28a.
- the coil current is amplitude-modulated by the pulse control signal from the pulse signal generator 28c to make the amplitude relatively large or small, and for example, the coil current is changed as shown in a rectangular wave 102 shown in FIG. Pulse modulation can be performed.
- the thermal plasma flame 100 can be periodically brought into a high temperature state at predetermined time intervals and a low temperature state having a lower temperature than the high temperature state.
- a thermal plasma flame whose temperature does not change can be generated by simply supplying a high-frequency current to the high-frequency oscillation coil 14b.
- the raw material is supplied intermittently, the raw material is supplied in synchronization with the high temperature state of the thermal plasma flame 100, and the raw material is completely evaporated at the high temperature state to form a mixture 45 in a gas phase state (see FIG. 2).
- the raw material is not supplied, and the supply amount of the quenching gas is increased to rapidly cool the gas-phase mixture 45 (see FIG. 2).
- the current amplitude is defined as a high value (HCL) and a low value (LCL) with respect to the coil current.
- the time taken is defined as the off time.
- the duty ratio (DF) is defined as the ratio of the ON time in one cycle (ON time / (ON time + OFF time) ⁇ 100 (%)).
- the ratio of the current amplitude of the coil (LCL / HCL ⁇ 100 (%)) is defined as the current modulation factor (SCL).
- the ON time, the OFF time, and one cycle are preferably on the order of microseconds to several seconds.
- the amplitude of the coil current is modulated using the pulse control signal
- it is preferable to perform the amplitude modulation using a predetermined waveform for example, a rectangular wave.
- the waveform is not limited to the rectangular wave, and a waveform composed of a triangular wave, a sawtooth wave, a reverse sawtooth wave, or a repetitive wave including a curve including a sine wave or the like can be used.
- the time modulation it is preferable that the change of the thermal plasma flame between the high temperature state and the low temperature state, the supply of the quenching gas, and the supply of the raw material have the same time change expressed by a function. This facilitates the timing of the supply of the quenching gas, the supply of the raw material, and the temperature of the thermal plasma flame.
- the intermittent supply unit 15 is for intermittently supplying the raw material into the plasma torch 14.
- the intermittent supply section 15 has a trigger circuit 30a, an electromagnetic coil 30b, and a valve 30c.
- the trigger circuit 30a is connected to the pulse signal generator 28c, receives a pulse control signal from the pulse signal generator 28c, and generates a TTL level signal in synchronization with the input pulse control signal. is there.
- the electromagnetic coil 30b is connected to the trigger circuit 30a, and opens and closes the valve 30c based on a TTL level signal from the trigger circuit 30a.
- the valve 30c controls the entry of the raw material for producing fine particles supplied together with the carrier gas from the raw material supply unit 12, for example, into the plasma torch 14, and the opening and closing are controlled by the electromagnetic coil 30b as described above. Is done.
- the raw material is intermittently supplied to the high-temperature thermal plasma flame 100.
- the pulse control signal 104 shown in FIG. 5A is output from the pulse signal generator 28c, and a TTL level signal synchronized with the pulse control signal 104 is generated by the trigger circuit 30a. Based on this TTL level signal, the valve 30c is opened and closed at predetermined time intervals by the timing signal 106 shown in FIG. As a result, for example, with the waveform 108 shown in FIG.
- the raw material powder is intermittently supplied into the plasma torch 14, and the raw material can be intermittently supplied to the high-temperature thermal plasma flame 100. Further, the supply timing of the quench gas is controlled based on the TTL level signal. Thereby, the timing of the supply of the quenching gas, the supply of the raw material, and the temperature state of the thermal plasma flame can be adjusted with high accuracy.
- the timing of the high-temperature state and the low-temperature state of the thermal plasma flame 100 may be feedback-controlled as described above. Further, the opening / closing timing of the valve 30c may be controlled. In this case, a TTL level signal generated by the trigger circuit 30a, that is, a signal that shifts the phase of the input signal to the electromagnetic coil 30b is generated, and this signal is supplied to the trigger circuit 30a. Thereby, the supply timing of the raw material can be set to a high-temperature state of the thermal plasma flame, that is, the on-time. As described above, in the manufacturing apparatus 10a, in addition to the time modulation of the quenched gas, the supply of the raw material and the temperature of the thermal plasma flame can also be time-modulated. By adjusting the timing of the time modulation, finer particles can be produced.
- the high-frequency modulation induction thermal plasma generating section 26 and the intermittent supply section 15 are configured to work together.
- the intermittent supply section 15 may operate alone.
- the intermittent supply unit 15 can supply the raw material without time modulation.
- the thermal plasma flame is time-modulated, and the supply amount of the raw material is constant regardless of time.
- the temperature of the quenched gas, the raw material and the temperature of the thermal plasma flame can be time-modulated.
- the supply of the quenched gas and the raw material may be time-modulated.
- the quenching gas and the temperature of the thermal plasma flame may be time-modulated.
- the temperature of the thermal plasma flame is time-modulated, but, for example, spectroscopic analysis may be used as described in Japanese Patent No. 5564370.
- the modulated induction thermal plasma flame is spectrally analyzed, and of the emission light of the modulation induction thermal plasma flame, the high frequency modulation induction thermal plasma generation unit generates the modulated induction thermal plasma flame based on the intensity of light having a wavelength derived from the raw material.
- the temperature condition is time-modulated.
- the method for producing fine particles using the production apparatus 10a is different from the method for producing fine particles using the above-described production apparatus 10 in that the thermal plasma flame is time-modulated, and the other production methods are the same. is there. Also in the method for producing fine particles using the production apparatus 10a, for example, Si powder having an average particle diameter of 10 ⁇ m or less is used as the raw material powder.
- the carrier gas, the plasma gas, and the quenching gas are the same as those in the method for producing fine particles using the production apparatus 10 described above.
- a thermal plasma flame is generated in the plasma torch 14. At this time, the temperature state is time-modulated and periodically changed to a high temperature state and a low temperature state lower than the high temperature state to obtain a modulated induction thermal plasma flame. .
- a thermal plasma flame for example, an Si gas is conveyed and supplied using an argon gas (first step). The supplied Si powder evaporates in a thermal plasma flame (modulated induction thermal plasma flame) to become a mixture 45 in a gaseous state (see FIG. 2).
- the quenching gas is supplied to the thermal plasma flame while changing the supply amount periodically (second step). As a result, the thermal plasma flame is rapidly cooled to generate Si fine particles (metal fine particles).
- the supply amount of the quenched gas be larger when the thermal plasma flame is in a low temperature state than in a high temperature state. In this case, it is more preferable to make the supply amount of the quenching gas zero when the thermal plasma flame is in a high temperature state. Then, the Si fine particles obtained in the chamber 16 are collected on the filter 18a of the collection unit 18 by the negative pressure (suction force) from the collection unit 18 by the vacuum pump 18b as described above.
- the quenching gas and the thermal plasma flame are time-modulated, but the supply of the raw material may be time-modulated.
- the raw material can be completely evaporated in a high temperature state to be in a gas phase state.
- the supply amount of the quenching gas is small as described above, it is preferable to increase the supply of the raw material.
- the controller 24 adjusts the supply timing of the quenching gas, the timing of the change in the temperature state of the thermal plasma flame, and the supply timing of the raw material.
- FIG. 6A is a graph showing a first example of the time modulation of the temperature of the quenched gas, the raw material and the thermal plasma flame
- FIG. 6B is a graph showing the second example of the time modulation of the temperature of the quenched gas, the raw material and the thermal plasma flame
- (C) is a graph showing a third example of the time modulation of the temperature of the quenched gas, the raw material and the thermal plasma flame
- (d) is the graph showing the temperature of the quenched gas, the raw material and the thermal plasma flame.
- FIG. 11 is a graph showing a fourth example of the time modulation of FIG. 6 (a) to 6 (d) show the temperature of the quenched gas, the raw material and the temperature of the thermal plasma flame, reference numeral 40 denotes the quenched gas, reference numeral 42 denotes the raw material, and reference numeral 44 denotes the heat. Shows a plasma flame.
- FIGS. 6A to 6D show time on the horizontal axis, normalized supply amount on the vertical axis, and normalized temperature. 6 (a) to 6 (d), when the numerical value on the vertical axis is small, it indicates that the supply amount is small and the temperature is low. When the numerical value on the vertical axis is large, it indicates that the supply amount is large and the temperature is high.
- the raw material and the thermal plasma flame can be kept constant, and only the quenched gas can be time-modulated into, for example, a sine wave.
- the quenching gas and the raw material can be time-modulated, for example, in a sine wave shape while keeping the thermal plasma flame constant. In this case, the phase of the quenched gas is shifted from that of the raw material, and the supply amount of the raw material is reduced when the supply amount of the quenched gas is large. Thereby, smaller fine particles can be manufactured.
- the manufacturing apparatus 10a for example, as shown in FIG.
- the quenching gas and the thermal plasma flame can be time-modulated in, for example, a sine wave shape while keeping the raw material constant.
- the phase of the quenched gas is shifted from that of the thermal plasma flame, and when the supply amount of the quenched gas is large, the thermal plasma flame is kept at a low temperature. Thereby, smaller fine particles can be manufactured.
- the quenching gas, the raw material, and the thermal plasma flame can be time-modulated in, for example, a sine wave shape. In this case, the phase of the quenched gas is shifted from that of the raw material and the thermal plasma flame. When the supply amount of the quenched gas is large, the supply amount of the raw material is reduced and the thermal plasma flame is kept at a low temperature. Thereby, finer particles can be produced.
- FIG. 7 is a schematic perspective view showing a model used for numerical calculation.
- the model 50 used for the numerical calculation shown in FIG. 7 is a model in which the lower end portion of the plasma torch 14 and the chamber 16 are modeled for numerical analysis, and has a cylindrical shape. One end 50a is on the side of the thermal plasma flame and the other end 50b is on the opposite side of the thermal plasma flame.
- a quenching gas supply unit 50c is set. The supply unit 50c is configured to supply quenched gas from eight directions at equal intervals.
- the symbol C of the model 50 indicates the central axis. With respect to the cylindrical model 50, the temperature distribution on the cut surface including the central axis C was obtained by numerical calculation.
- the maximum flow rate of the quenched gas was 50 liters / minute, and the average flow rate was 25 liters / minute.
- the phase difference of the thermal plasma flame and the flow rate of the quenched gas that was time-modulated was ⁇ / 2.
- the time modulation period of the quenched gas was 1 second.
- FIGS. 8A to 8D are schematic diagrams showing the temperature distribution when the quenched gas is time-modulated
- FIGS. 9A to 9D are schematic diagrams showing the temperature distribution when the time-modulated is not modulated. It is.
- FIGS. 8A to 8D correspond to FIGS. 9A to 9D, respectively, and show temperature distributions at the same time.
- FIGS. 8A and 9A show a time of 0.0 second
- FIGS. 8B and 9B show a time of 0.25 second
- FIGS. 8C and 9C Shows a time of 0.5 seconds
- FIGS. 8D and 9D show a time of 0.75 seconds.
- 9 (a) to 9 (d) no time change of the temperature distribution is observed.
- FIGS. 8 (a) to 8 (d) it can be seen that in FIG. It is understood that a large cooling effect can be obtained by time-modulating the supply amount of the quenching gas in this way.
- the region 51 is near the quenching gas supply unit 50
- FIG. 10 is a graph showing the distribution of the time average temperature on the central axis of the model
- FIG. 11 is a graph showing the time change of the temperature distribution on the central axis of the model.
- FIGS. 10 and 11 show the results of FIGS. 8 (a) to 8 (d) and FIGS. 9 (a) to 9 (d).
- the horizontal axis shows the position of the central axis
- the vertical axis shows the normalized temperature.
- the smaller the numerical value of the position of the central axis of the horizontal axis is the position on the one end 50a side of the model 50, and the larger the numerical value of the position of the central axis is the other end 50b. Side position.
- reference numeral 46 in FIG. 10 indicates a time-modulated quenched gas
- reference numeral 47 indicates a non-time-modulated quenched gas
- Reference numeral 48 in FIG. 11 indicates a time-modulated quenched gas
- reference numeral 49 indicates a non-time-modulated quenched gas.
- the average temperature at the center of the chamber is not different between the time-modulated quenched gas and the non-time-modulated quenched gas.
- the modulated one has a lower temperature.
- FIG. 11 it can be seen that the temperature at the center of the chamber is low by modulating the supply amount of the quenched gas with time. By utilizing the region where the temperature is low, a large cooling effect can be obtained, and smaller particles can be produced.
- FIGS. 12A to 12H are schematic diagrams showing temperature distributions when the flow rates of the hot plasma flame and the quenched gas are time-modulated
- FIGS. 13A to 13H are diagrams of the hot plasma flame and the quenched gas.
- It is a schematic diagram which shows the locus
- the quenched gas affects the movement of the particles, but the particles do not affect the quenched gas.
- the particle diameter is assumed to be 100 nm, monodispersion is assumed, and the specific heat of the particles is not considered.
- the particles recoil on the wall, and at one end 50a the particles rest.
- FIGS. 12 (a) to 12 (h) and FIGS. 13 (a) to 13 (h) correspond to each other, and show the temperature distribution and the state of the particles at the same time.
- FIGS. 12 (a) to 12 (h) and FIGS. 13 (a) to 13 (h) show changes in the thermal plasma flame and the quenched gas shown in FIG. 6 (c).
- FIGS. 12 (a) and 13 (a) show a time of 0.25 seconds
- FIGS. 12 (b) and 13 (b) show a time of 0.30 seconds
- FIGS. 12 (d) and 13 (d) indicate a time of 0.50 second
- FIGS. 12 (e) and 13 (e) indicate a time of 0.55 second
- FIGS. 12 (f) and 13 (f) show a time of 0.60 second
- FIGS. 12 (g) and 13 (g) show a time of 0.65 second
- FIGS. 12 (h) and 13 (h). ) Indicates a time of 0.70 seconds.
- FIGS. 12A and 12B and FIGS. 12G and 12H When the temperature of the thermal plasma flame is high. In FIGS. 12A and 12B and FIGS. 12G and 12H, the temperature is high. In FIGS. 12C and 12D, the flow rate of the quenched gas is large, and the temperature is low. As shown in FIG. 12 (e), the quenched gas flows into the chamber and the internal temperature is low. Regarding the state of the particles, as shown in FIGS. 13C to 13E, the particles are distributed on one end 50a side and stay near the tail of the thermal plasma flame. Further, as shown in FIGS. 13F and 13G, when the flow rate of the quenching gas was large, the particles were dispersed toward the other end 50b.
- the manufacturing apparatus 10 and the manufacturing apparatus 10a of the present embodiment can manufacture nano-sized Si fine particles using, for example, Si powder as a raw material.
- the present invention is not limited to this, and it is also possible to produce fine particles such as oxides, metals, nitrides, and carbides by using particles of other elements as a raw material for producing fine particles. In this case, fine particles can be produced even when the slurry is formed.
- the average particle diameter is appropriately set so that the powder easily evaporates in the thermal plasma flame.
- the average particle diameter is, for example, 100 ⁇ m or less, preferably 10 ⁇ m, in terms of BET diameter.
- the thickness is more preferably 5 ⁇ m or less.
- any type of raw material can be used as long as it can be evaporated by a thermal plasma flame, but the following materials are preferred.
- An oxide, a double oxide, an oxide solid solution, a metal, an alloy, a hydroxide, a carbonate, a halide, a sulfide, a nitride, a carbide, a hydride, a metal salt, or a metal organic compound may be appropriately selected.
- a simple oxide refers to an oxide composed of one kind of element other than oxygen
- a composite oxide refers to an oxide composed of a plurality of kinds of oxides
- a double oxide refers to two or more kinds of oxides. Is a solid in which oxides different from oxide solid solution are uniformly dissolved with each other.
- a metal refers to a material composed of only one or more metal elements
- an alloy refers to a material composed of two or more metal elements.
- the structural state of the metal includes a solid solution, a eutectic mixture, and a metal. Intermetallic compounds or mixtures thereof.
- a hydroxide refers to a compound composed of a hydroxyl group and one or more metal elements
- a carbonate compound refers to a compound composed of a carbonate group and one or more metal elements
- a halide refers to a halogen element.
- one or more metal elements, and sulfide means one composed of sulfur and one or more metal elements.
- nitride refers to a substance composed of nitrogen and one or more metal elements
- carbide refers to a substance composed of carbon and one or more metal elements
- hydride refers to hydrogen and one or more metal elements. Of the above metal elements.
- the metal salt refers to an ionic compound containing at least one or more metal elements
- the metal organic compound refers to an organic compound containing a bond of at least one of the metal elements and at least one of C, O, and N elements.
- metal alkoxides and organometallic complexes are examples of metal alkoxides and organometallic complexes.
- Zr (OH) 4 as a hydroxide
- CaCO 3 as a carbonate compound
- MgF 2 as a halide
- ZnS as a sulfide
- TiN as a nitride
- SiC as a carbide
- TiH 2 as a hydride And the like.
- the present invention is basically configured as described above. As described above, the fine particle production apparatus and the fine particle production method of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiment, and various improvements or changes may be made without departing from the gist of the present invention. Of course, you may.
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Abstract
Description
例えば、特許文献1には、炭化チタン微粒子の製造方法が記載されている。
特許文献1では、チタンまたはチタン酸化物の粉末をキャリアガスにより分散させ、チタンまたはチタン酸化物の粉末を熱プラズマ炎中に供給する工程と、熱プラズマ炎の終端部に、冷却用ガスと炭素源として反応性ガスを供給し、炭化チタン微粒子を生成する工程とを備えており、反応性ガスの供給量を変えて生成される炭化チタン微粒子の酸素含有量を変えることが記載されている。
また、特許文献1には、チタンまたはチタン酸化物の粉末を、炭素源である炭素を含む液体状の物質に分散させてスラリーにし、スラリーをキャリアガスにより液滴化させて熱プラズマ炎中に供給する工程を備えており、スラリーのフィード量が一定になるように制御し、スラリーを投入する際のキャリアガスの流量を変えて、生成される炭化チタン微粒子の酸素含有量を変えることが記載されている。
特許文献1に記載の製造方法では、ナノサイズの微粒子を製造することができるものの、現在、よりサイズが小さい微粒子が要求されており、この要求に十分に対応できない。
本発明の目的は、より小さな微粒子を製造する微粒子の製造装置および微粒子の製造方法を提供することにある。
また、前記プラズマ発生部は、前記熱プラズマ炎として、温度状態が時間変調された変調誘導熱プラズマ炎を発生させ、前記変調誘導熱プラズマ炎を周期的に高温状態と、前記高温状態よりも温度が低い低温状態とにさせることが好ましい。
前記原料供給部は、前記変調誘導熱プラズマ炎が前記高温状態のときに、前記原料の供給量を多くすることが好ましい。
前記原料供給部は、前記原料を、粒子状に分散させた状態で、前記熱プラズマ炎中に供給することが好ましい。
前記原料供給部は、前記原料を液体に分散させてスラリーにし、前記スラリーを液滴化して前記熱プラズマ炎中に供給することが好ましい。
また、前記熱プラズマ炎は、温度状態が時間変調されて周期的に高温状態と、この高温状態よりも温度が低い低温状態とにされる変調誘導熱プラズマ炎であることが好ましい。
前記第1の工程では、前記変調誘導熱プラズマ炎が前記高温状態のときに、前記原料の供給量を多くすることが好ましい。
前記第1の工程では、前記原料を、粒子状に分散させた状態で、前記熱プラズマ炎中に供給することが好ましい。
前記第1の工程では、前記原料を液体に分散させてスラリーにし、前記スラリーを液滴化して前記熱プラズマ炎中に供給することが好ましい。
図1は本発明の実施形態の微粒子の製造装置の一例を示す模式図である。
なお、製造装置10は、微粒子であれば、その種類は特に限定されるものではなく、原料の組成を変えることにより、金属微粒子以外にも微粒子として、酸化物微粒子、窒化物微粒子、炭化物微粒子、酸窒化物微粒子等の微粒子を製造することができる。
製造装置10は、原料供給部12と、プラズマトーチ14と、チャンバー16と、回収部18と、プラズマガス供給部20と、プラズマ発生部21と、気体供給部22と、制御部24とを有する。
また、原料供給部12とプラズマトーチ14との間の供給管13に、後述するように間歇供給部15を設けてもよい。製造装置10では間歇供給部15は必須の構成ではないが、間歇供給部15を設けた方がより好ましい。
プラズマトーチ14の下方にチャンバー16が設けられ、チャンバー16に回収部18が設けられている。プラズマ発生部21はプラズマトーチ14に接続されており、後述するようにプラズマ発生部21により、プラズマトーチ14の内部に熱プラズマ炎100が発生される。
原料供給部12は、原料を熱プラズマ炎100中に供給することができれば、特に限定されるものではなく、原料を粒子状に分散させた状態で熱プラズマ炎100中に供給するものと、原料をスラリーにし、スラリーを液滴化した形態で熱プラズマ炎100中に供給するものとの2通りの方式を用いることができる。
例えば、原料供給部12は、例えば、原料の粉末を貯蔵する貯蔵槽(図示せず)と、原料の粉末を定量搬送するスクリューフィーダ(図示せず)と、スクリューフィーダで搬送された原料の粉末が最終的に散布される前に、これを粒子の状態に分散させる分散部(図示せず)と、キャリアガス供給源(図示せず)とを有する。
キャリアガス供給源から押し出し圧力がかけられたキャリアガスとともに原料の粉末は供給管13を介してプラズマトーチ14内の熱プラズマ炎100中へ供給される。
原料供給部12は、原料の粉末の凝集を防止し、分散状態を維持したまま、原料の粉末を、粒子状に分散させた状態でプラズマトーチ14内に散布することができるものであれば、その構成は特に限定されるものではない。キャリアガスには、例えば、アルゴンガス(Arガス)、窒素ガス等の不活性ガスが用いられる。
スラリーの形態で原料を供給する場合、原料の粉末を水等の液体に分散させてスラリーにする。なお、スラリー中の原料の粉末と水との混合比は、特に限定されるものではなく、例えば、質量比で5:5(50%:50%)である。
このように、二流体ノズル機構は、スラリーに高圧をかけ、気体である噴霧ガス(キャリアガス)によりスラリーを噴霧することができ、スラリーを液滴化させるための一つの方法として用いられる。
なお、上述の二流体ノズル機構に限定されるものではなく、一流体ノズル機構を用いてもよい。さらに他の方法として、例えば、回転している円板上にスラリーを一定速度で落下させて遠心力により液滴化する(液滴を形成する)方法、スラリー表面に高い電圧を印加して液滴化する(液滴を発生させる)方法等が挙げられる。
図2に示すように、プラズマトーチ14は、石英管14aと、石英管14aの外面に設けられた、プラズマトーチ14の外側を取り巻く高周波発振用コイル14bとで構成されている。プラズマトーチ14の上部には、供給管13が挿入される供給口14cがその中央部に設けられており、プラズマガス供給口14dがその周辺部(同一円周上)に形成されている。
供給管13により、例えば、粉末状の原料と、アルゴンガスまたは水素ガス等のキャリアガスとがプラズマトーチ14内に供給される。
また、プラズマトーチ14内における圧力雰囲気は、微粒子の製造条件に応じて適宜決定されるものであり、例えば、大気圧以下である。ここで、大気圧以下の雰囲気については、特に限定されないが、例えば、5Torr(666.5Pa)~750Torr(99.975kPa)とすることができる。
チャンバー16に、気体供給部22が接続されている。気体供給部22から供給される急冷ガスにより、チャンバー16内で、原料に応じた材料の微粒子(図示せず)が生成される。また、チャンバー16は冷却槽として機能するものである。
急冷ガスは、冷却する機能を発揮するものであれば、特に限定されるものではない。急冷ガスには、例えば、原料と反応しない、アルゴンガス、窒素ガス、ヘリウムガス等の不活性ガスが用いられる。急冷ガスは、これ以外に、水素ガスを含有してもよい。また、急冷ガスは、原料と反応する反応性ガスを含有してよい。反応性ガスとしては、例えば、メタン、エタン,プロパン,ブタン,アセチレン,エチレン,プロピレン,ブテン等の炭素数4以下の各種の炭化水素ガス等が挙げられる。
原料に応じた材料の微粒子の生成直後の微粒子同士が衝突し、凝集体を形成することで粒子径の不均一が生じると、品質低下の要因となる。しかしながら、熱プラズマ炎の尾部100b(終端部)に向かって、急冷ガスを供給することにより、急冷ガスが微粒子を希釈することで、微粒子同士が衝突して凝集することが防止される。
また、チャンバー16の内壁面に沿って、急冷ガスを供給することにより、微粒子の回収の過程において、微粒子のチャンバー16の内壁への付着が防止され、生成した微粒子の収率が向上する。
気体供給部22における急冷ガスの時間変調は、例えば、気体供給源からの供給量を一定にし、調整弁に、例えば、ボールバルブを用いて、供給量を時間変調する。
複数の方向から急冷ガスを供給する場合、供給タイミングは、特に限定されるものではなく、複数の方向から同期して急冷ガスを供給する。これ以外にも、例えば、時計回りまたは反時計回りの順で、急冷ガスを供給してもよい。この場合、急冷ガスにより、チャンバー16内に旋回流等の気流が生じる。複数の方向から急冷ガスを供給する場合、供給順を決定することなく、ランダムに供給してもよい。
原料供給部12は、原料の熱プラズマ炎100中への供給量を時間変調して、原料を熱プラズマ炎100中に供給するものでもよい。これにより、熱プラズマ炎100に変動がなくても、時間的に変動する。
この場合、例えば、供給管13に間歇供給部15を設ける。間歇供給部15により、チャンバー16内に原料を時間変調して供給する。原料の供給量の変化は、特に限定されるものではなく、サイン波状でも、三角波状でも、方形波状でも、のこぎり波状でもよい。
時間変調の際、急冷ガスの供給と原料の供給とは、関数で表される時間変化が同じであることが好ましい。これにより、急冷ガスの供給と原料の供給とのタイミングを合わせやすくなる。
上述のように、製造装置10は、急冷ガスを時間変調して供給することができ、これにより、熱プラズマ炎をさらに冷却することができ、温度が低い状態を作り出すことができる。このため、より小さい微粒子を製造することができる。
さらには、製造装置10は、原料の供給も、時間変調することができる。この場合、急冷ガスの時間変調とともに、原料の供給も時間変調することにより、さらに小さい微粒子を製造することができる。なお、急冷ガスの供給と原料の供給とのタイミングは、急冷ガスの供給量が少ないときに、原料の供給を多くすることが好ましい。
まず、金属微粒子の原料の粉末として、例えば、平均粒子径が10μm以下のSiの粉末を原料供給部12に投入する。
プラズマガスに、例えば、アルゴンガスおよび水素ガスを用いて、高周波発振用コイル14b(図2参照)に高周波電圧を印加し、プラズマトーチ14内に熱プラズマ炎100を発生させる。
また、気体供給部22から熱プラズマ炎100の尾部100b(図2参照)、すなわち、熱プラズマ炎100の終端部に、急冷ガスとして、例えば、アルゴンガスとメタンガスの混合ガスを供給する。
このとき、急冷ガスを時間変調させて、すなわち、供給量を周期的に変えて、急冷ガスを熱プラズマ炎100に供給する(第2の工程)。これにより、熱プラズマ炎100が急冷されてSi微粒子(金属微粒子)が生成されるが、このとき、チャンバー16内に温度が低い領域が生じ、より小さいSi微粒子が得られる。
そして、チャンバー16内で得られたSi微粒子は、真空ポンプ18bによる回収部18からの負圧(吸引力)によって回収部18のフィルター18aに捕集される。
製造装置10では、急冷ガスを時間変調したが、さらに原料の供給を時間変調してもよい。この場合、急冷ガスの供給量が少ないときに、原料の供給を多くすることが好ましい。急冷ガスの供給タイミングと、原料の供給タイミングとは制御部24で調整される。
図3は本発明の実施形態の微粒子の製造装置の他の例を示す模式図であり、図4はパルス変調時のコイル電流の時間変化についての説明図である。
図3に示す微粒子の製造装置10a(以下、単に製造装置10aという)において、図1に示す製造装置10と同一構成物には、同一符号を付して、その詳細な説明は省略する。
図3に示す製造装置10aは、図1に示す製造装置10に比して、プラズマ発生部21(図1参照)にかえて、高周波変調誘導熱プラズマ発生部26を有する点が異なり、それ以外の構成は、図1に示す製造装置10と同じ構成である。
熱プラズマ炎が所定時間間隔で周期的に高温状態と、この高温状態よりも温度が低い低温状態にされたもの、すなわち、熱プラズマ炎の温度状態が時間変調されたもののことを変調誘導熱プラズマ炎という。
高周波変調誘導熱プラズマ発生部26は、高周波インバータ電源28aと、インピーダンス整合回路28bと、パルス信号発生器28cと、FETゲート信号回路28dとを有する。
高周波インバータ電源28aは、例えば、整流回路と、MOSFETインバータ回路とを有する。高周波インバータ電源28aにおいて、整流回路は、例えば、入力電源として三相交流を用いるものであり、三相全波整流回路により交流-直流変換を行った後、IGBT(絶縁ゲートバイポーラトランジスタ)を用いたDC-DCコンバータにより、その出力電圧値を変化させる。
高周波インバータ電源28aは、出力側にインピーダンス整合回路28bが接続されている。このインピーダンス整合回路28bは、コンデンサ、共振コイルからなる直列共振回路により構成されており、プラズマ負荷を含めた負荷インピーダンスの共振周波数が高周波インバータ電源28aの駆動周波数領域内となるようにインピーダンスマッチングを行うものである。
FETゲート信号回路28dは、パルス信号発生器28cで発生されたパルス制御信号に基づく変調信号を、高周波インバータ電源28aのMOSFETインバータ回路のMOSFETのゲートに供給するものである。これにより、パルス信号発生器28cによるパルス制御信号でコイル電流を振幅変調して振幅を相対的に大きくするか、または小さくして、例えば、図4に示す矩形波102のように、コイル電流をパルス変調することができる。コイル電流をパルス変調することにより、熱プラズマ炎100を、所定時間間隔で周期的に高温状態と、この高温状態よりも温度が低い低温状態にすることができる。高周波変調誘導熱プラズマ発生部26においては、高周波発振用コイル14bに、単に高周波電流を供給することにより、温度状態が変わらない熱プラズマ炎を発生させることもできる。
原料を間歇的に供給する場合、熱プラズマ炎100の高温状態に同期させて原料を供給して、原料を高温状態で完全に蒸発させて気相状態の混合物45(図2参照)とし、さらに低温状態の時には、原料を供給せずに、急冷ガスの供給量を多くして気相状態の混合物45(図2参照)を急冷する。
また、矩形波102において、オン時間、オフ時間、および1サイクルは、いずれもマイクロ秒から数秒オーダーであることが好ましい。
時間変調の際、熱プラズマ炎の高温状態と低温状態との変化、急冷ガスの供給および原料の供給とは、関数で表される時間変化が同じであることが好ましい。これにより、急冷ガスの供給、原料の供給、および熱プラズマ炎の温度状態のタイミングを合わせやすくなる。
トリガ回路30aは、パルス信号発生器28cに接続されており、パルス信号発生器28cからパルス制御信号が入力されて、この入力されたパルス制御信号に同期してTTLレベルの信号を発生するものである。
電磁コイル30bは、トリガ回路30aに接続されており、トリガ回路30aからのTTLレベルの信号に基づいてバルブ30cを開閉させるものである。
本実施形態においては、図5(a)に示すパルス制御信号104がパルス信号発生器28cから出力されて、このパルス制御信号104に同期したTTLレベルの信号がトリガ回路30aで作成される。このTTLレベルの信号に基づいて、図5(b)に示すタイミング信号106で、バルブ30cが所定の時間間隔で開閉される。その結果、図5(c)に示す波形108で、例えば、原料粉末がプラズマトーチ14内に間歇的に供給され、原料を高温状態の熱プラズマ炎100に間歇的に供給することができる。
さらに、TTLレベルの信号に基づいて、急冷ガスの供給タイミングを制御する。これにより、急冷ガスの供給、原料の供給、および熱プラズマ炎の温度状態のタイミングを高い精度で合わることができる。
このように、製造装置10aでは、急冷ガスの時間変調に加え、原料の供給および熱プラズマ炎の温度も時間変調することができる。時間変調のタイミングを調整することより、さらに小さい微粒子を製造することができる。
製造装置10aでは、上述のように、急冷ガス、原料および熱プラズマ炎の温度の時間変調が可能であるが、製造装置10のように、急冷ガスと原料の供給とを時間変調してもよく、急冷ガスと熱プラズマ炎の温度とを時間変調してもよい。
また、製造装置10aでは、熱プラズマ炎の温度を時間変調しているが、例えば、特許第5564370号公報に記載されているように分光分析を用いてもよい。この場合、変調誘導熱プラズマ炎について分光分析し、変調誘導熱プラズマ炎の放射光のうち、原料に由来する波長の光の強度に基づいて高周波変調誘導熱プラズマ発生部により変調誘導熱プラズマ炎の温度状態を時間変調させる。
製造装置10aを用いた微粒子の製造方法でも、原料の粉末として、例えば、平均粒子径が10μm以下のSiの粉末を用いる。キャリアガス、プラズマガス、および急冷ガスは、上述の製造装置10を用いた微粒子の製造方法と同じである。
熱プラズマ炎(変調誘導熱プラズマ炎)中に、例えば、アルゴンガスを用いてSiの粉末を気体搬送して供給する(第1の工程)。供給されたSiの粉末は、熱プラズマ炎(変調誘導熱プラズマ炎)中で蒸発して気相状態の混合物45(図2参照)となる。
このとき、急冷ガスを熱プラズマ炎に対して、供給量を周期的に変えて供給する(第2の工程)。これにより、熱プラズマ炎が急冷されてSi微粒子(金属微粒子)が生成されるが、このとき、チャンバー16内に温度が低い領域が生じ、さらに小さいSi微粒子が得られる。なお、熱プラズマ炎が低温状態のときに、高温状態のときよりも急冷ガスの供給量を多くすることが好ましい。この場合、熱プラズマ炎が高温状態のときに、急冷ガスの供給量をゼロにすることがより好ましい。
そして、チャンバー16内で得られたSi微粒子は、上述のように真空ポンプ18bによる回収部18からの負圧(吸引力)によって回収部18のフィルター18aに捕集される。
さらには、上述のように急冷ガスの供給量が少ないときに、原料の供給を多くすることが好ましい。急冷ガスの供給タイミングと、熱プラズマ炎の温度状態の変化のタイミングと、原料の供給タイミングとは制御部24で調整される。
図6(a)は急冷ガス、原料および熱プラズマ炎の温度の時間変調の第1の例を示すグラフであり、(b)は急冷ガス、原料および熱プラズマ炎の温度の時間変調の第2の例を示すグラフであり、(c)は急冷ガス、原料および熱プラズマ炎の温度の時間変調の第3の例を示すグラフであり、(d)は急冷ガス、原料および熱プラズマ炎の温度の時間変調の第4の例を示すグラフである。
なお、図6(a)~(d)は、いずれも急冷ガス、原料および熱プラズマ炎の温度を示すものであり、符号40は急冷ガスを示し、符号42は原料を示し、符号44は熱プラズマ炎を示す。図6(a)~(d)は、横軸に時間、縦軸に規格化した供給量と、規格化した温度を示す。図6(a)~(d)において、縦軸の数値が小さいと供給量が小さいこと、および温度が低いことを示す。縦軸の数値が大きいと供給量が多いこと、および温度が高いことを示す。
また、図6(b)に示すように、熱プラズマ炎を一定にして、急冷ガスと原料を、例えば、サイン波状に時間変調することができる。この場合、急冷ガスと原料とは、位相をずらしており、急冷ガスの供給量が多いときに、原料の供給量を小さくしている。これにより、より小さい微粒子を製造することができる。
製造装置10aでは、例えば、図6(c)に示すように、原料を一定にして、急冷ガスと熱プラズマ炎を、例えば、サイン波状に時間変調することができる。この場合、急冷ガスと熱プラズマ炎とは、位相をずらしており、急冷ガスの供給量が多いときに、熱プラズマ炎を低温状態にしている。これにより、より小さい微粒子を製造することができる。
さらには、製造装置10aでは、例えば、図6(d)に示すように、急冷ガス、原料、および熱プラズマ炎を、例えば、サイン波状に時間変調することができる。この場合、急冷ガスと、原料および熱プラズマ炎とは、位相をずらしており、急冷ガスの供給量が多いときに、原料の供給量を少なくし、かつ熱プラズマ炎を低温状態にしている。これにより、さらに小さい微粒子を製造することができる。
図7は数値計算に用いたモデルを示す模式的斜視図である。
図7に示す数値計算に用いたモデル50は、プラズマトーチ14の下端部とチャンバー16を、数値解析可能なモデル化したものであり、円筒状である。一方の端部50aが熱プラズマ炎側であり、他方の端部50bが熱プラズマ炎の反対側である。また、モデル50では、急冷ガスの供給部50cを設定している。供給部50cは、等間隔に8方向から急冷ガスが供給される構成である。モデル50の符号Cは中心軸を示す。
円筒状のモデル50について、中心軸Cを含む切断面における温度分布を数値計算を用いて求めた。
なお、数値計算において、モデル50の一方の端部50aに、境界条件として、熱を与えた。計算条件としては、急冷ガスの流量だけを時間変調したもの(図8(a)~(d)参照)、熱プラズマ炎および急冷ガスの流量を時間変調したもの(図12(a)~(h)参照)とした。また、比較のために、時間変調していないもの(図9(a)~(d)参照)についても数値計算した。
急冷ガスはアルゴンガスとした。また、急冷ガスの流量は最大流量を50リットル/分とし、平均流量を25リットル/分とした。熱プラズマ炎および急冷ガスの流量を時間変調したものは、位相差をπ/2とした。急冷ガスの時間変調の周期は、1秒とした。
図9(a)~(d)では温度分布の時間変化が見られない。一方、図8(a)~(d)では、図8(c)において、領域51のように急激な温度低下が生じていることが見られた。このように急冷ガスの供給量を時間変調することにより、大きな冷却効果が得られることがわかる。なお、領域51は、急冷ガスの供給部50cの近傍である。
図10および図11では、横軸に中心軸の位置、縦軸に規格化した温度を示している。図10および図11において、横軸の中心軸の位置の数値が小さい方が、モデル50の一方の端部50a側の位置であり、中心軸の位置の数値が大きい方が他方の端部50b側の位置である。
また、図10の符号46は急冷ガスを時間変調したものを示し、符号47は時間変調していないものを示す。図11の符号48は急冷ガスを時間変調したものを示し、符号49は時間変調していないものを示す。
図11に示すように、急冷ガスの供給量を時間変調することにより、チャンバーの中心部の温度が低いことがわかる。この温度が低い領域を利用することにより、大きな冷却効果が得られ、より小さい微粒子を製造することができる。
なお、粒子の軌跡では、急冷ガスが粒子の動きに影響を及ぼすが、粒子が急冷ガスに影響を及ぼさないとした。
また、粒子径を100nmとし、単一分散と仮定し、粒子の比熱は考慮していない。粒子は壁面で反跳するとし、一方の端部50aで粒子は静止するとした。
図12(a)および図13(a)は時間0.25秒を示し、図12(b)および図13(b)は時間0.30秒を示し、図12(c)および図13(c)は時間0.40秒を示し、図12(d)および図13(d)は時間0.50秒を示し、図12(e)および図13(e)は時間0.55秒を示し、図12(f)および図13(f)は時間0.60秒を示し、図12(g)および図13(g)は時間0.65秒を示し、図12(h)および図13(h)は時間0.70秒を示す。
粒子の状態については、図13(c)~(e)に示すように、粒子が一方の端部50a側に分布しており、熱プラズマ炎の尾部付近に滞留している。また,図13(f)および(g)に示すように、急冷ガスの流量が多いと粒子が他方の端部50bに向かって分散した。
例えば、原料としては、熱プラズマ炎により蒸発させられるものであれば、その種類を問わないが、好ましくは、以下のものがよい。すなわち、原子番号3~6、11~15、19~34、37~52、55~60、62~79および81~83の元素よりなる群から選ばれる少なくとも1種を含む、単体酸化物、複合酸化物、複酸化物、酸化物固溶体、金属、合金、水酸化物、炭酸化合物、ハロゲン化物、硫化物、窒化物、炭化物、水素化物、金属塩または金属有機化合物を適宜選択すればよい。
さらに、水酸化物としてはZr(OH)4、炭酸化合物としてはCaCO3、ハロゲン化物としてはMgF2、硫化物としてはZnS、窒化物としてはTiN、炭化物としてはSiC、水素化物としてはTiH2等を挙げることができる。
12 原料供給部
13 供給管
14 プラズマトーチ
14a 石英管
14b 高周波発振用コイル
14c 供給口
14d プラズマガス供給口
14e 石英管
14f 冷却水
15 間歇供給部
16 チャンバー
16a 上流チャンバー
16b 下流チャンバー
18 回収部
18a フィルター
18b 真空ポンプ
20 プラズマガス供給部
21 プラズマ発生部
22 気体供給部
24 制御部
26 高周波変調誘導熱プラズマ発生部
28a 高周波インバータ電源
28b インピーダンス整合回路
28c パルス信号発生器
28d FETゲート信号回路
30a トリガ回路
30b 電磁コイル
30c バルブ
45 混合物
50 モデル
50a 端部
50b 端部
50c 供給部
100 熱プラズマ炎
102 矩形波
104 パルス制御信号
106 タイミング信号
108 波形
C 中心軸
Claims (14)
- 微粒子の製造装置であって、
微粒子製造用の原料を熱プラズマ炎中に供給する原料供給部と、
内部に前記熱プラズマ炎が発生され、前記原料供給部により供給される前記原料を前記熱プラズマ炎にて蒸発させて気相状態の混合物とするプラズマトーチと、
前記プラズマトーチの内部に前記熱プラズマ炎を発生させるプラズマ発生部と、
前記熱プラズマ炎に、急冷ガスを供給する気体供給部とを有し、
前記気体供給部は、前記急冷ガスの供給量を時間変調して供給する、微粒子の製造装置。 - 前記原料供給部は、前記原料の前記熱プラズマ炎中への供給量を時間変調して、前記原料を前記熱プラズマ炎中に供給する、請求項1に記載の微粒子の製造装置。
- 前記プラズマ発生部は、前記熱プラズマ炎として、温度状態が時間変調された変調誘導熱プラズマ炎を発生させ、前記変調誘導熱プラズマ炎を周期的に高温状態と、前記高温状態よりも温度が低い低温状態とにさせる、請求項1または2に記載の微粒子の製造装置。
- 前記気体供給部は、前記変調誘導熱プラズマ炎が前記低温状態のときに、前記急冷ガスの供給量を多くする、請求項3に記載の微粒子の製造装置。
- 前記原料供給部は、前記変調誘導熱プラズマ炎が前記高温状態のときに、前記原料の供給量を多くする、請求項3または4に記載の微粒子の製造装置。
- 前記原料供給部は、前記原料を、粒子状に分散させた状態で、前記熱プラズマ炎中に供給する、請求項1~5のいずれか1項に記載の微粒子の製造装置。
- 前記原料供給部は、前記原料を液体に分散させてスラリーにし、前記スラリーを液滴化して前記熱プラズマ炎中に供給する、請求項1~6のいずれか1項に記載の微粒子の製造装置。
- 微粒子の製造方法であって、
微粒子製造用の原料を熱プラズマ炎に供給する第1の工程と、
前記原料を前記熱プラズマ炎で蒸発させ気相状態の混合物とし、前記熱プラズマ炎に急冷ガスを供給する第2の工程とを有し、
前記第2の工程では、前記急冷ガスの供給量を時間変調して供給する、微粒子の製造方法。 - 前記第1の工程では、前記原料を、前記熱プラズマ炎中への供給量を時間変調して、前記熱プラズマ炎中に供給する、請求項8に記載の微粒子の製造方法。
- 前記熱プラズマ炎は、温度状態が時間変調されて周期的に高温状態と、この高温状態よりも温度が低い低温状態とにされる変調誘導熱プラズマ炎である、請求項8または9に記載の微粒子の製造方法。
- 前記第2の工程では、前記変調誘導熱プラズマ炎が前記低温状態のときに、前記急冷ガスの供給量を多くする、請求項10に記載の微粒子の製造方法。
- 前記第1の工程では、前記変調誘導熱プラズマ炎が前記高温状態のときに、前記原料の供給量を多くする、請求項10または11に記載の微粒子の製造方法。
- 前記第1の工程では、前記原料を、粒子状に分散させた状態で、前記熱プラズマ炎中に供給する、請求項8~12のいずれか1項に記載の微粒子の製造方法。
- 前記第1の工程では、前記原料を液体に分散させてスラリーにし、前記スラリーを液滴化して前記熱プラズマ炎中に供給する、請求項8~12のいずれか1項に記載の微粒子の製造方法。
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