JP2006102737A - Fine particle manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fine particle manufacturing method for such as oxide, nitride and carbide capable of obtaining high-quality fine particles having even particle size with high productivity. <P>SOLUTION: The fine particle manufacturing method, wherein the fine particles are produced by introducing a fine particle manufacturing material into a thermal plasma flame 24 to form a mixture in a gaseous condition and quenching the mixture in the gaseous condition, and the method of manufacturing the fine particle, wherein the process that introduces the fine particle manufacturing material into the thermal plasma flame disperses the fine particle manufacturing material in a flammable material to form slurry and changes the slurry to droplets to be introduced into the thermal plasma flame. As forms of the material to be introduced into the thermal plasma flame, powder, colloidal solution, liquid or the like are effective. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing fine particles using a thermal plasma method, and more particularly to a method for producing fine particles capable of producing fine particles having a fine and uniform particle size.

  Fine particles such as oxide fine particles, nitride fine particles, and carbide fine particles are used for electrical insulating materials such as semiconductor substrates, printed circuit boards, and various electric insulating parts, high-hardness and high-precision machine tool materials such as dies and bearings, and grain boundary capacitors. , Production of sintered materials such as functional materials such as humidity sensors, precision sintered molding materials, thermal spray parts such as materials that require high-temperature wear resistance such as engine valves, and fuel cell electrodes And electrolyte materials and various catalysts. By using such fine particles, the bonding strength, denseness, or functionality of dissimilar ceramics or dissimilar metals in a sintered body or irradiated part is improved.

  One method for producing such fine particles is a gas phase method. The vapor phase method includes a chemical method in which various gases are chemically reacted at a high temperature and a physical method in which particles are decomposed and evaporated by irradiation with a beam such as an electron or a laser to generate fine particles.

  One of the gas phase methods is a thermal plasma method. The thermal plasma method is a method of instantly evaporating raw materials in thermal plasma and then rapidly solidifying them to produce fine particles. Also, it is clean, highly productive, and has a high heat capacity at high temperatures. It has many advantages such as being compatible and being relatively easy to combine compared with other gas phase methods. For this reason, the thermal plasma method is actively used as a method for producing fine particles.

  In the conventional method of producing fine particles using the thermal plasma method, the raw material is powdered, and the powdered raw material (powder raw material, powder) is dispersed together with a carrier gas etc. and directly put into the plasma. Thus, fine particles are manufactured.

  Patent Document 1 relates to a conventional technique for introducing a powdered raw material into a thermal plasma flame, compositing both powder materials of metal fine particles and a coating layer, and making the raw material mixture into a thermal plasma in an inert or reducing atmosphere. A method for producing oxide metal-coated fine particles by supplying into a flame and evaporating raw materials to form a gas-phase mixture and then rapidly cooling the mixture is disclosed.

JP 2000-219901 A

  However, the method for producing fine particles described in Patent Document 1 uses a method of directly introducing a powdered raw material into a thermal plasma flame, and the powdered raw material tends to aggregate, Since it is difficult to monodisperse, the raw materials cannot be completely reacted in the thermal plasma flame, adversely affecting the uniformity of the generated fine particles and causing a reduction in quality. In addition, when the raw material is in a powder form, it is difficult to always supply a constant amount accurately into the thermal plasma flame, and the generated fine particles tend to be non-uniform.

  The object of the present invention is to solve the problems based on the prior art and to produce high-quality fine particles having a uniform particle size with high productivity as in Japanese Patent Application No. 2003-415560, which is the prior application of the present inventors. It is providing the manufacturing method of the microparticles | fine-particles which can be obtained by this.

  In order to achieve the above object, the first aspect of the method for producing fine particles according to the present invention is to introduce a fine particle production material into a thermal plasma flame to obtain a gas phase mixture, which is a mixture of the gas phase state. A method for producing fine particles, characterized in that fine particles are produced by quenching, wherein the step of introducing the fine particle production material into a thermal plasma flame comprises introducing the fine particle production material into the combustible material. The slurry is dispersed to form a slurry, and the slurry is formed into droplets and introduced into the thermal plasma flame (claim 1).

  Further, in the second aspect of the method for producing fine particles according to the present invention, the fine particle production material is introduced into a thermal plasma flame to form a gas phase mixture, and the gas phase state mixture is rapidly cooled, A method for producing fine particles, characterized in that the step of introducing the fine particle production material into a thermal plasma flame is characterized in that the fine particle production material is slurried using a dispersion medium and a combustible material. The slurry is formed into droplets and introduced into the thermal plasma flame (claim 2).

  Further, in the third aspect of the method for producing fine particles according to the present invention, a fine particle production material is introduced into a thermal plasma flame to form a gas phase mixture, and the gas phase state mixture is rapidly cooled, A method for producing fine particles, characterized in that the step of introducing the fine particle production material into a thermal plasma flame further disperses the fine particle production material after dispersing the fine particle production material in a dispersion medium. A material is added to form a slurry, and the slurry is formed into droplets and introduced into the thermal plasma flame (claim 3).

  Further, the fourth aspect of the method for producing fine particles according to the present invention is to form a gas phase mixture by introducing the fine particle production material into a thermal plasma flame, and rapidly quench the gas phase mixture. A method for producing fine particles, characterized in that the step of introducing the fine particle production material into a thermal plasma flame comprises suspending the fine particle production material in a dispersion medium to form a colloid solution. The colloidal solution is made into droplets and introduced into the thermal plasma flame (claim 4).

  Further, a fifth aspect of the method for producing fine particles according to the present invention is to make a gas phase mixture by introducing the fine particle production material into a thermal plasma flame, and by rapidly cooling the gas phase mixture, A method for producing fine particles, characterized in that the step of introducing the fine particle production material into a thermal plasma flame comprises suspending the fine particle production material in a combustible material and a colloid solution. The colloidal solution is made into droplets and introduced into the thermal plasma flame (claim 5).

  Further, a sixth aspect of the method for producing fine particles according to the present invention is a method of introducing a fine particle production material into a thermal plasma flame to form a gas phase mixture, and quenching the gas phase state mixture, A method for producing fine particles, characterized in that the step of introducing the fine particle production material into a thermal plasma flame suspends the fine particle production material in a dispersion medium and a combustible material. The colloidal solution is made into droplets and introduced into the thermal plasma flame (claim 6).

  Further, a seventh aspect of the method for producing fine particles according to the present invention is that a fine particle production material is introduced into a thermal plasma flame to form a gas phase mixture, and the gas phase state mixture is rapidly cooled. A method for producing fine particles, characterized by producing fine particles, wherein the step of introducing the fine particle production material into a thermal plasma flame further comprises suspending the fine particle production material in a dispersion medium. A flammable material is added to form a colloidal solution, and the colloidal solution is formed into droplets and introduced into the thermal plasma flame (claim 7).

  Further, an eighth aspect of the method for producing fine particles according to the present invention is to form a gas phase mixture by introducing the fine particle production material into a thermal plasma flame, and rapidly quench the gas phase mixture. A method for producing fine particles, characterized by producing fine particles, wherein the step of introducing the fine particle production material into a thermal plasma flame comprises dissolving the fine particle production material in a solvent to form a solution. In the form of droplets and introduced into the thermal plasma flame (claim 8).

  Further, a ninth aspect of the method for producing fine particles according to the present invention is to form a gas phase mixture by introducing the fine particle production material into a thermal plasma flame, and rapidly quench the gas phase state mixture, A method for producing fine particles, characterized in that the step of introducing the fine particle production material into a thermal plasma flame comprises dissolving the fine particle production material using a combustible material to form a solution. The solution is made into droplets and introduced into the thermal plasma flame (claim 9).

  Further, a tenth aspect of the method for producing fine particles according to the present invention is a method of introducing a fine particle production material into a thermal plasma flame to form a gas phase mixture, and quenching the gas phase mixture. A method for producing fine particles, characterized in that the step of introducing the fine particle production material into a thermal plasma flame dissolves the fine particle production material using a solvent and a combustible material. The solution is formed into droplets and introduced into the thermal plasma flame.

  In addition, an eleventh aspect of the method for producing fine particles according to the present invention is to form a gas phase mixture by introducing the fine particle production material into a thermal plasma flame, and rapidly quench the gas phase mixture. A method for producing fine particles, characterized by producing fine particles, wherein the step of introducing the fine particle production material into a thermal plasma flame is further combustible after the fine particle production material is dissolved in a solvent. A material is added to form a solution, and the solution is formed into droplets and introduced into the thermal plasma flame (claim 11).

  Further, a twelfth aspect of the method for producing fine particles according to the present invention is that a fine particle production material is introduced into a thermal plasma flame to form a gas phase mixture, and the gas phase state mixture is rapidly cooled, A method for producing fine particles, characterized in that the step of introducing the fine particle production material into a thermal plasma flame is characterized in that the fine particle production material is dispersed using a carrier gas and a combustible material. The dispersed material for producing fine particles is introduced into the thermal plasma flame (claim 12).

  The definition of the slurry, colloidal solution, and solution in the present specification is a colloidal solution (which is not recognized by a normal optical microscope in a liquid, but in which solid particles larger than atoms or small molecules are dispersed. (Also called sol), larger particles, that is, particles in a size that can be seen with an ordinary optical microscope are dispersed, and those that are ionized are supersaturated. Each of them is called a solution including a state where precipitates exist. However, the present invention does not relate to such a dispersed state. In short, a material for producing fine particles including a precursor for forming fine particles or a decomposition product thereof includes a gas in some state. The state in which it is dispersed in the dispersion medium is the starting state.

  Here, it is preferable that the combustible material has an effect of increasing the temperature of the thermal plasma flame and stabilizing the thermal plasma. As the combustible material, various liquid or solid materials can be used. When using a solid combustible material, it is preferable to disperse or dissolve the solid combustible material in a solvent (including a combustible material used as a solvent).

  In addition, it is preferable to add one or a mixture of two or more selected from the group consisting of a surfactant, a polymer and a coupling agent to the slurry, colloidal solution, solution or dispersed fine particle production material ( Claims 14 to 17).

  The component constituting the fine particles is at least one selected from the group consisting of the elements of atomic numbers 3 to 6, 11 to 15, 19 to 34, 37 to 52, 55 to 60, 62 to 79, and 81 to 83. Elemental oxides, complex oxides, complex oxides, oxide solid solutions, metals, alloys, hydroxides, carbonates, halides, sulfides, nitrides, carbides, hydrides, metal salts or metal organic compounds (Claim 18).

According to the method for producing fine particles according to the present invention, it is possible to produce fine particles having high productivity, a uniform particle size, and high quality.
More specifically, according to the method for producing fine particles according to the present invention, in addition to the use for conventionally known electrical insulating materials such as a semiconductor substrate, a printed circuit board, and various electrical insulating parts, the electrode of the fuel cell It is possible to produce fine particles having high functionality that can be applied to new fields such as electrolyte materials and various catalysts.

  In the case of using a flammable material, it is possible to increase the amount of collected fine particles according to the present invention by increasing the mass of the flammable material relative to the total mass of the dispersion medium and the fine particle production material. .

[First embodiment]
Hereinafter, as a first embodiment for carrying out a method for producing fine particles according to the present invention, a production method and a production apparatus for producing fine particles using a slurry will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic cross-sectional view showing the overall configuration of a fine particle production apparatus for carrying out a fine particle production method according to an embodiment of the present invention. The fine particle production apparatus 10 according to the present embodiment includes a plasma torch 12 that generates thermal plasma, a raw material supply apparatus 14 that supplies a fine particle production material (hereinafter referred to as a raw material) into the plasma torch 12, and a chamber that generates fine particles. 16 and a collection unit 20 that collects the generated fine particles 18. FIG. 2 shows a partially enlarged view of the vicinity of the plasma torch 12.

  As shown in FIG. 2, the plasma torch 12 includes a quartz tube 12a and a high-frequency oscillation coil 12b surrounding the outside. In the upper part of the plasma torch 12, an introduction pipe 12d for introducing the raw material and the carrier gas into the plasma torch 12 is provided in the center thereof, and a plasma gas inlet 12c is formed in the periphery thereof.

  The plasma gas is sent from the plasma gas supply source 22 to the plasma gas inlet 12c. Examples of the plasma gas include argon, nitrogen, hydrogen, oxygen, and the like. For example, two types of plasma gas are prepared in the plasma gas supply source 22. The plasma gas is sent from the plasma gas supply source 22 into the plasma torch 12 as indicated by an arrow P through the ring-shaped plasma gas inlet 12c. Then, a high frequency current is supplied to the high frequency oscillation coil 12b, and a thermal plasma flame 24 is generated.

  The outside of the quartz tube 12a is surrounded by a tube (not shown) formed concentrically, and cooling water (not shown) circulates between this tube and the quartz tube 12a. The tube 12a is cooled with water, and the quartz tube 12a is prevented from becoming too hot due to the thermal plasma flame 24 generated in the plasma torch 12.

  The raw material supply device 14 for supplying the raw material into the plasma torch 12 is connected to an introduction pipe 12 d provided at the upper part of the plasma torch 12 via a pipe 26. A feature of the present invention is that the raw material supplied from the raw material supply device 14 is a mixture of a powder raw material in a combustible solvent as a combustible material and stirred to form a slurry 14a, or a powder raw material is put in a dispersion medium. Stirring is performed, and a combustible solvent is further added and stirred to form a slurry 14a. The slurry 14 a is supplied from the raw material supply device 14.

  The raw material supply device 14 includes a container 14b for containing the slurry 14a, a stirrer 14c for stirring the slurry 14a in the container 14b, and a pump 14d for applying high pressure to the slurry 14a via the pipe 26 and supplying the slurry 14a into the plasma torch 12. And a spray gas supply source 14e. The spray gas subjected to the extrusion pressure is supplied from the spray gas supply source 14e together with the slurry 14a into the plasma torch 12 through the introduction pipe 12d as indicated by an arrow g. Thereby, the slurry 14a is sprayed in the plasma torch 12, and the slurry 14a can be made into droplets. Argon, nitrogen, hydrogen, oxygen, air or the like is used as the atomizing gas. As described above, a mechanism that applies high pressure to the slurry 14a and sprays the slurry with a spray gas that is a gas is called a two-fluid nozzle mechanism, and is used as one method for forming the slurry 14a into droplets.

  On the other hand, fine particles 18 are generated in a chamber 16 provided adjacent to the lower side of the plasma torch 12. That is, the slurry 14a sprayed (droplet-formed) from the raw material supply device 14 into the plasma torch 12 reacts in the thermal plasma flame 24 to become a vapor phase mixture which is evaporated, and immediately after that, in the chamber 16 Is rapidly cooled to produce fine particles 18.

  A collection unit 20 that collects the generated fine particles 18 is provided at a lower side portion of the chamber 16. The recovery unit 20 includes a recovery chamber 20a, a filter 20b provided in the recovery chamber 20a, and a vacuum pump (not shown) connected via a pipe 20c provided in the upper portion of the recovery chamber 20a. The generated fine particles 18 are sucked into a collection chamber 20a by being sucked by a vacuum pump (not shown), and are collected while remaining on the surface of the filter 20b.

  Next, a method for producing fine particles using slurry according to the first embodiment of the present invention will be described using the fine particle production device 10 while describing the operation of the fine particle production device 10 described above.

  In the method for producing fine particles according to the present embodiment, first, a powdered raw material (hereinafter also referred to as “powder raw material”) is dispersed in a dispersion medium, and then combustible in the dispersion medium in which the powder raw material is dispersed. Add and mix the organic solvent into a slurry. As an example, the mass ratio of the powder raw material, the dispersion medium, and the combustible solvent in the slurry may be 4: 3: 3 (40%: 30%: 30%). The slurry can be prepared by appropriately changing the mass ratio with the organic solvent.

  More specifically, when the total mass of the powder raw material, the dispersion medium and the combustible solvent is 100%, the powder raw material is 1 to 80% of the total, and the rest is 100%, the dispersion medium is Of these, 1 to 99%, the flammable solvent may be appropriately changed within the range of 99 to 1%, and the total mass is always 100%.

  Here, the kind of powder raw material is not limited as long as it can be evaporated by a thermal plasma flame, but the following are preferable. That is, a simple oxide containing at least one selected from the group consisting of the elements of atomic numbers 3 to 6, 11 to 15, 19 to 34, 37 to 52, 55 to 60, 62 to 79, and 81 to 83, and a composite An oxide, a double oxide, an oxide solid solution, a metal, an alloy, a hydroxide, a carbonate compound, a halide, a sulfide, a nitride, a carbide, a hydride, a metal salt, or a metal organic compound may be appropriately selected.

  The simple oxide means an oxide composed of one kind of element other than oxygen, the composite oxide means that the fine particles are composed of plural kinds of oxides, and the double oxide means two or more kinds of oxides. A higher-order oxide made of an oxide, which is a solid in which oxides different from an oxide solid solution are uniformly dissolved. A metal means only one or more kinds of metal elements, and an alloy means two or more kinds of metal elements. Its structure is a solid solution, eutectic mixture, metal. It may form an intercalation compound or a mixture thereof.

  A hydroxide is a compound composed of a hydroxyl group and one or more metal elements, a carbonate compound is a compound composed of a carbonate group and one or more metal elements, and a halide is a halogen element. And one or more metal elements, and a sulfide means one composed of sulfur and one or more metal elements. Nitride means nitrogen and one or more metal elements, carbide means carbon and one or more metal elements, and hydride means hydrogen and one or more metal elements. It consists of metal elements. A metal salt refers to an ionic compound containing at least one metal element, and a metal organic compound refers to an organic compound including a bond between one or more metal elements and at least one of C, O, and N elements. And metal alkoxides and organometallic complexes.

For example, as a single oxide, titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), calcium oxide (CaO), silicon oxide (SiO ₂ ), aluminum oxide (alumina: Al ₂ O ₃ ), silver oxide (Ag) ₂ O), iron oxide, magnesium oxide (MgO), manganese oxide (Mn ₃ O ₄ ), yttrium oxide (Y ₂ O ₃ ), cerium oxide, samarium oxide, beryllium oxide (BeO), vanadium oxide (V ₂ O ₅ ), Chromium oxide (Cr ₂ O ₃ ), barium oxide (BaO), and the like.

The composite oxides include lithium aluminate (LiAlO ₂ ), yttrium vanadate, calcium phosphate, calcium zirconate (CaZrO ₃ ), lead zirconate titanium, iron oxide titanium (FeTiO ₃ ), and cobalt cobalt oxide (CoTiO ₃ ). As a double oxide, barium stannate (BaSnO ₃ ), (meth) barium titanate (BaTiO ₃ ), lead titanate (PbTiO ₃ ), solid solution of zirconium oxide and calcium oxide in barium titanate, etc. Can be mentioned.
Further, 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, and TiH ₂ as a hydride. Etc.

  Further, the flammable solvent used here has an effect of stabilizing the thermal plasma flame 24 and may have a boiling point of 20 ° C. to 400 ° C. As the flammable solvent, kerosene, gasoline, octane, alcohols and the like are used. By introducing the combustible solvent into the dispersion medium in which the powder raw material is dispersed, the temperature of the reaction field is increased and the reaction is promoted, and the flame is expanded by the combustion of the combustible solvent itself. The thermal plasma flame 24 used for the reaction is more stable than when no flammable solvent is used, and a stable continuous operation can be performed.

  As described above, as the combustible material, not only liquid but also various solid materials can be used. When using a solid combustible material, it is preferable to disperse or dissolve the solid combustible material in a solvent (including a combustible material used as a solvent).

  Furthermore, when preparing the slurry 14a, you may add the 1 type, or 2 or more types of mixture chosen from the group which consists of surfactant, a polymer, and a coupling agent. As the surfactant, for example, a sorbitan fatty acid ester which is a nonionic surfactant, as the polymer, for example, ammonium polyacrylate, and as the coupling agent, for example, a silane coupling agent or the like is used. By adding one or more mixtures selected from the group consisting of a surfactant, a polymer, and a coupling agent to the slurry 14a, the powder raw material is more effectively prevented from aggregating in the liquid, The slurry 14a can be stabilized. In addition, liquids, such as water and alcohol, are used for the dispersion medium of the slurry 14a, for example.

  As shown in FIG. 1, the slurry 14 a created as described above is placed in a container 14 b of the raw material supply device 14 and stirred by a stirrer 14 c. Thereby, the powder raw material in the liquid is prevented from being precipitated, and the slurry 14a in which the powder raw material is dispersed is maintained.

  Next, the slurry 14a formed into droplets is introduced into the thermal plasma flame 24 by the spray gas supplied from the spray gas supply source 14e, and the slurry 14a is evaporated to form a gas phase mixture. In other words, the slurry 14a in droplet form is supplied into the plasma torch 12 and is introduced into the thermal plasma flame 24 generated in the plasma torch 12 to evaporate. Become.

  Since the dropletized slurry 14 a needs to be in a gas phase state in the thermal plasma flame 24, the temperature of the thermal plasma flame 24 is changed to the dropletized slurry introduced into the thermal plasma flame 24. It must be higher than the boiling point of the raw materials involved. On the other hand, the higher the temperature of the thermal plasma flame 24, the more preferable because the raw material easily enters a gas phase state, but the temperature is not particularly limited, and the temperature is appropriately selected according to the raw material. For example, the temperature of the thermal plasma flame 24 can be set to 6000 ° C. by changing the gas conditions and the like, and it is considered that the temperature reaches about 10000 ° C. in theory.

  The atmosphere of the thermal plasma flame 24 in the plasma torch 12 is preferably atmospheric pressure or lower. The atmosphere at atmospheric pressure or lower is not particularly limited, but for example, 5 Torr to 750 Torr can be considered.

  The mixture in the vapor phase obtained by reacting in the thermal plasma flame 24 and evaporating the slurry 14 a is rapidly cooled in the chamber 16, whereby fine particles 18 are generated. The generated fine particles 18 are sucked by a vacuum pump (not shown) and collected by the filter 20b of the collection unit 20.

  Further, in the method for producing fine particles according to the present embodiment, the powder raw material may be directly dispersed in the combustible solvent to form the slurry 14a. The combustible solvent is not necessarily added to the dispersion liquid in which the powder raw material is dispersed. There is no need to make a slurry.

  In general, use of air, nitrogen, argon, hydrogen, or the like as the spray gas (or carrier gas) is conceivable. However, when the generated fine particles are oxide particles, the spray gas (or carrier gas) is used. ) May be oxygen.

  The fine particles produced by the production method according to the present embodiment have a narrow particle size distribution width, that is, a uniform particle size, and are less mixed with coarse particles. Specifically, the average particle size is from 1 nm. 200 nm. In the method for producing fine particles according to the present embodiment, for example, oxide fine particles, more specifically, fine particles such as simple oxides, composite oxides, double oxides, oxide solid solutions, and the like can be produced. In addition, fine particles with chemical changes using metals, alloys, hydroxides, carbonates, halides, sulfides, nitrides, carbides, hydrides, metal salts or metal organic compounds as raw materials can be produced. it can.

  In the state where the powder raw material is dispersed in the dispersion medium as in the manufacturing method according to the present embodiment, the aggregation of the powder raw material is eliminated and the particles of the raw material are dispersed in the dispersion medium. By introducing a combustible solvent into such a dispersion medium, the reaction temperature rises and the thermal plasma flame generation region is expanded. By receiving this action, the reaction is promoted and the amount of evaporation of the powder raw material is increased, so that the recovery rate of the generated fine particles is increased in the manufacturing method according to the present embodiment. Furthermore, the generation of a flame due to the combustion of the combustible solvent expands the thermal plasma generation region, and the stability of the thermal plasma flame can be obtained, so that stable continuous operation can be performed.

  Further, in the manufacturing method according to the present embodiment, the slurry 14a that has been made into droplets is supplied into the plasma torch 12, so that the supply amount is always controlled to be constant as compared with the conventional method in which the powder raw material is directly supplied. Becomes easy. As a result, it is possible to always introduce a certain amount of slurry into the thermal plasma flame 24 to cause the reaction, and the fine particles to be produced are controlled in composition, making it difficult to form coarse particles and having a particle size distribution. High-quality fine particles with a narrow and uniform particle size and good quality can be produced.

  Furthermore, since the powder raw material is made into the slurry 14a, there is no limitation due to the solubility of the raw material as in the case where a metal salt that is a raw material of fine particles is dissolved in a solution to form a solution. That is, the slurry 14a can be mixed with a powder raw material in an amount higher than its solubility in the liquid. For this reason, the mass productivity of the produced fine particles can be increased.

Furthermore, since the slurry 14a can be obtained simply by putting the powder raw material in the liquid and stirring, handling such as preparation of the raw material is easy.
In order to efficiently cool the gas phase mixture in the chamber 16, a cooling gas is blown into the chamber 16, or the generated fine particles are prevented from adhering to the inner wall of the chamber 16. A gas is preferably blown along the inner wall of the chamber 16.

[Second Embodiment]
Next, as a second embodiment of the present invention, a manufacturing method for manufacturing fine particles using a colloid solution will be described.

  As described above, in the present specification, the difference between the slurry and the colloidal solution is mainly in the size and shape of the particles dispersed in the liquid. The colloidal particles do not necessarily have a general particle shape, and may be amorphous. Therefore, the fine particle production apparatus used in the fine particle production method according to the present embodiment can have the same configuration as the fine particle production apparatus (see FIG. 1) used in the first embodiment described above. Accordingly, a method for producing fine particles using the fine particle production apparatus described above will be described below.

  As a method for preparing a colloidal solution in the method for producing fine particles according to the present embodiment, for example, there is a sol-gel method (referred to as a metal alkoxide method or simply an alkoxide method) using various metal alkoxides as raw materials. As the solvent used here, an alcohol solvent (ethanol, propanol, etc.) can be preferably used. In addition to the sol-gel method, a colloidal solution can be prepared by various liquid phase synthesis methods such as a coprecipitation method and an emulsion method.

  As metal alkoxides, those using various metals as raw materials are commercially available. For example, Si, Ti, Zr, Al, etc., La-Al, Mg-Al, Ni-Al, Zr-Al, Ba-Zr, etc. Examples thereof include those using (bimetallic alkoxide) as a raw material. These metal alkoxides are usually solid but may be liquid.

  In the case of using a combustible material (combustible solvent), various materials described in the description of the embodiment can be suitably used. By mixing this combustible material with the colloidal solution described above, the reaction temperature rises and the reaction is promoted. In addition, the flame is expanded by the combustion of the combustible material itself. By being more stable, stable continuous operation can be performed.

  As described above, the colloidal solution prepared by dispersing and mixing the fine particle production material, the solvent, and the combustible material is put into the container 14b of the raw material supply apparatus 14 shown in FIG. To stir. Thereby, the dispersion state in a colloidal solution is maintained favorable. Note that the fine particle manufacturing material, the solvent, and the combustible material may be put into the container 14 b and the colloid solution may be prepared by the raw material supply device 14.

Thereafter, the fine particles are generated by the same method as the fine particle production method using the powder raw material as a slurry shown in the above-described embodiment.
The fine particles produced by the fine particle production method according to the present embodiment have a narrow particle size distribution width, that is, a uniform particle size, and there is little mixing of coarse particles. Specifically, the average particle size is 3 ~ 70 nm.

  Also by the method for producing fine particles according to the present embodiment, for example, fine oxide particles, more specifically fine particles such as simple oxides, composite oxides, double oxides, oxide solid solutions, and the like can be produced. In addition, fine particles with chemical changes using metals, alloys, hydroxides, carbonates, halides, sulfides, nitrides, carbides, hydrides, metal salts or metal organic compounds as raw materials can be produced. it can.

[Third embodiment]
Next, as a third embodiment of the present invention, a method for producing fine particles using a solution in which raw materials are dissolved in a solvent will be described. In addition, the form of the raw material (raw material for fine particle production) used in the present embodiment may be solid, liquid, or any other type.
The fine particle production apparatus used in the fine particle production method according to the present embodiment can also have the same configuration as the fine particle production apparatus (see FIG. 1) used in the first embodiment described above. Accordingly, a method for producing fine particles using the fine particle production apparatus described above will be described below.

  In the method for producing fine particles according to this embodiment, first, raw materials are dissolved in a solvent to form a solution. As described above, the term “solution” here refers to an ionized state including a state in which a precipitate is present in a supersaturated state. As the solvent used here, water, acid, alkali, alcohol, ketone, ether and the like can be suitably used. In addition, since the raw material is dissolved in the solvent used, it is limited by the solvent used, but nitrates, acetates, ammonium salts, hydroxides, metal alkoxides, organometallic complexes, and the like can be used.

  When a solution is prepared as described above, the concentration can be increased to saturation solubility or a concentration exceeding this to some extent (supersaturated state). In addition, a flammable material can be added to and mixed with this solution. The mixing ratio of the raw material, the solvent, and the combustible material is as described above.

In addition, when using a metal salt or a metal alkoxide as a raw material, a solution is prepared by dissolving these in a solvent.
Here, as the metal salt, at least one metal selected from the group consisting of the elements of atomic numbers 3 to 6, 11 to 15, 19 to 34, 37 to 52, 55 to 60, 62 to 79, and 81 to 83 is used. What is necessary is just to select from the ionic compound containing an element. Specific examples include aluminum nitrate, zinc nitrate, yttrium nitrate, zirconium nitrate, zirconium acetate, and titanium chloride.

  When using a metal alkoxide, in addition to those shown in the second embodiment, Li, Na, Cu, Ca, Sr, Ba, Zn, B, Al, Ga, Y, Si, Ge, Pb , P, Sb, V, Ta, W, La, Nd and other metal alkoxides can be used.

  Moreover, about the combustible material (flammable solvent), the various things demonstrated in description of the said embodiment can be used conveniently. By mixing the combustible material and the metal salt solution, the reaction temperature rises and the reaction is promoted. In addition, the flame is expanded by the combustion of the combustible material itself. By being more stable, stable continuous operation can be performed.

  As described above, a solution prepared by mixing a metal salt that is a material for producing fine particles, a solvent, and a combustible material is put into the container 14b of the raw material supply apparatus 14 shown in FIG. Stir well. Thereby, the solution in which the metal salt and the combustible material are uniformly dispersed in the solution is maintained. Note that the metal salt, the solvent, and the combustible material may be put into the container 14 b and the solution may be prepared by the raw material supply device 14.

Thereafter, the fine particles are generated by the same method as the fine particle production method using the powder raw material as a slurry shown in the above-described embodiment.
The fine particles produced by the fine particle production method according to the present embodiment have a narrow particle size distribution width, that is, a uniform particle size, and there is little mixing of coarse particles. Specifically, the average particle size is 3 ~ 100 nm.

  In the method for producing fine particles according to the present embodiment, since a solution in which a powder raw material is dissolved in a solvent is used, a metal that is a raw material for producing fine particles can be easily dispersed, and the dispersibility is also extremely high. Very expensive. Therefore, fine particles having a finer and uniform particle diameter can be generated.

[Fourth embodiment]
Next, as a fourth embodiment of the present invention, a method for producing fine particles in which powder raw materials are dispersed (without using a solvent or the like) and introduced into a thermal plasma flame will be described.
The fine particle production apparatus used in the fine particle production method according to this embodiment uses the raw material supply apparatus 14 of the fine particle production apparatus (see FIG. 1) used in the first to third embodiments described above, using powder raw materials. Fine particles are produced using a fine particle production apparatus that has been changed to an apparatus suitable for the above. However, here too, as in the first to third embodiments described above, the powder raw material needs to be dispersed when introduced into the thermal plasma flame.

Therefore, it is preferable that the material supply apparatus in the present embodiment can be quantitatively introduced into the thermal plasma flame inside the plasma torch while maintaining the powder raw material in a dispersed state (so-called primary particle state). As a material supply apparatus having such a function, for example, an apparatus such as a powder dispersion apparatus disclosed in Japanese Patent No. 3217415 can be used.
Hereinafter, the fine particle manufacturing apparatus used in this embodiment will be described first.

  FIG. 3 shows a schematic configuration of a raw material supply apparatus 140 when a powder material (that is, a powder raw material) is used as the fine particle manufacturing material. 3 mainly includes a storage tank 142 for storing powder raw materials, a screw feeder 160 for quantitatively conveying the powder raw materials, and finally dispersing the powder raw materials conveyed by the screw feeder 160. It is comprised from the dispersion | distribution part 170 disperse | distributed to the state of a primary particle before being performed.

  Although not shown, the storage tank 142 is provided with an exhaust pipe and an intake pipe. The storage tank 142 is a pressure vessel sealed with an oil seal or the like, and is configured to control the internal atmosphere. In addition, an inlet (not shown) for introducing the powder raw material is provided in the upper part of the storage tank 142, and the powder raw material 144 is introduced into the storage tank 142 from the inlet and stored.

  Inside the storage tank 142, a stirring shaft 146 and a stirring blade 148 connected thereto are provided in order to prevent the stored powder raw material 144 from agglomerating. The stirring shaft 146 is rotatably arranged in the storage tank 142 by an oil seal 150a and a bearing 152a. Moreover, the end of the stirring shaft 146 outside the storage tank 142 is connected to a motor 154a, and its rotation is controlled by a control device (not shown).

  Further, a screw feeder 160 is provided below the storage tank 142 to enable quantitative conveyance of the powder raw material 144. The screw feeder 160 includes a screw 162, a shaft 164 of the screw 162, a casing 166, and a motor 154 b that is a rotational power source of the screw 162. The screw 162 and the shaft 164 are provided across the lower part in the storage tank 142. The shaft 164 is rotatably disposed in the storage tank 142 by an oil seal 150b and a bearing 152b.

  The end of the shaft 164 outside the storage tank 142 is connected to a motor 154b, and the rotation thereof is controlled by a control device (not shown). Further, a casing 166 that is a cylindrical passage that connects the opening of the lower portion of the storage tank 142 and a dispersion unit 170 described later and wraps the screw 162 is provided. The casing 166 extends to the middle of the dispersion unit 170.

As shown in FIG. 3, the dispersion unit 170 includes an outer tube 172 that is extrapolated and fixed to a part of the casing 166, and a rotating brush 176 that is implanted at the tip of the shaft 164, and is fixed by a screw feeder 160. The conveyed powder raw material 144 can be primarily dispersed.
The end portion of the outer tube 172 opposite to the end portion on which the outer tube is fixed is a truncated cone shape, and also has a dispersion chamber 174 that is a truncated cone-shaped space. Further, a transport pipe 182 for transporting the powder raw material dispersed in the dispersion unit 170 is connected to the end portion.

  The tip of the casing 166 is open, and a shaft 164 extends to the dispersion chamber 174 inside the outer tube 172 beyond the opening, and a rotating brush 176 is provided at the tip of the shaft 164. A gas supply port 178 is provided on the side surface of the outer tube 172, and a space provided by the outer wall of the casing 166 and the inner wall of the outer tube 172 constitutes a gas passage 180 through which the introduced gas passes. Yes.

  The rotating brush 176 is a needle-like member made of a relatively flexible material such as nylon or a hard material such as steel wire, and the radial direction of the shaft 164 extends from the inside of the casing 166 near the tip to the inside of the dispersion chamber 174. It is formed by being densely planted. Here, the length of the needle-like member is such a length that the tip of the needle-like member comes into contact with the peripheral wall in the casing 166.

  In the dispersion unit 170, a gas for dispersion / conveyance is ejected from a pressure gas supply source (not shown) through the gas supply port 178 and the gas passage 180 from the radially outer side of the rotary brush 176 toward the rotary brush 176, The powder raw material 144 conveyed quantitatively is dispersed into the primary particles by passing between the needle-like members of the rotating brush 176.

  The angle formed by the frustoconical bus of the dispersion chamber 174 and the shaft 164 of the screw 162 described above is arranged to be an angle of about 30 degrees. Further, the volume of the dispersion chamber 174 is preferably small. If the volume is large, the powder raw material 144 dispersed by the rotating brush 176 adheres to the inner wall of the dispersion chamber 174 before entering the transfer pipe 182 and rescatters. In addition, there arises a problem that the concentration of the supplied dispersion material is not constant.

  One end of the transfer tube 182 is connected to the outer tube 172, and the other end is connected to the plasma torch 12. In addition, it is preferable that the transport pipe 182 has a pipe length portion that has a pipe length that is 10 times or more of the pipe diameter and that at least the flow rate of the gas containing the material dispersed in the middle is 20 m / sec or more. Thereby, aggregation of the powder raw material 144 dispersed in the primary particle state by the dispersing unit 170 can be prevented, and the powder raw material 144 can be dispersed inside the plasma torch 12 while maintaining this state.

  The fine particle production apparatus according to this embodiment is the same as that in the first to third embodiments except that the raw material supply apparatus 140 having the above-described configuration is connected to the plasma torch 12 shown in FIGS. Since the apparatus has the same configuration as that of the apparatus, the method for producing fine particles according to the present embodiment can be implemented using this.

Next, a method for producing fine particles in the present embodiment will be described.
A flammable material that stabilizes the thermal plasma flame by burning itself can be added to and mixed with the powder raw material used as the fine particle manufacturing material. At this time, the mass ratio between the powder raw material and the combustible material may be appropriately selected. For example, the mass ratio between the powder raw material and the combustible material may be 95: 5. Here, the powder raw material can be evaporated in a thermal plasma flame, and its particle size is preferably about 10 μm or less.

  The powder raw material is composed of elements having atomic numbers 3 to 6, 11 to 15, 19 to 34, 37 to 52, 55 to 60, 62 to 79, and 81 to 83, as in the above-described embodiments. Single oxide, composite oxide, double oxide, oxide solid solution, metal, alloy, hydroxide, carbonate, halide, sulfide, nitride, carbide, hydride, containing at least one selected from the group A metal salt or a metal organic compound may be appropriately selected.

Specific examples include graphite, titanium oxide, aluminum oxide, aluminum, silica, silicon, and the like.
Further, as the combustible material, an element that does not remain as an impurity in the generated fine particles, for example, a material composed of C, H, O, and N can be suitably used. Specific examples include citric acid, glycerin, ethylene glycol, and the like, but are not limited thereto.

The mixture of the powder raw material and the combustible material as described above is sufficiently stirred so as to be uniformly mixed, and this mixture is put into the storage tank 142 of the raw material supply apparatus 140. Here, the powder raw material and the combustible material may be stirred after being put into the storage tank 142.
The mixture is dispersed in the thermal plasma flame 24 in the plasma torch 12. The dispersed powder raw material becomes an evaporated vapor phase mixture, and then rapidly cooled in the chamber 16 to generate fine particles of the vapor phase mixture.

  In the method for producing fine particles according to the present embodiment, since the powder raw material is dispersed in the thermal plasma flame 24 together with the combustible material, the fine particles can be easily dispersed at a high temperature. Fine particles having a particle size can be generated.

  Specific examples of the first to fourth embodiments will be described below.

[Example 1]
An embodiment in which slurry is used as a raw material will be described using the fine particle production apparatus shown in FIG.

Fine particles of aluminum oxide (Al ₂ O ₃ ) were produced by the method for producing fine particles according to the first embodiment. First, powder raw materials, a dispersant (sorbitan fatty acid ester) and alcohol as a dispersion medium are mixed, and these and zirconia beads having a diameter of 0.5 mm are put into a bead mill (manufactured by Kotobuki Industries Co., Ltd.), and this mixed solution is pulverized. Processed. At this time, powder raw materials include titanium oxide, zirconium oxide, calcium oxide, silicon oxide, aluminum oxide, silver oxide, iron oxide, magnesium oxide, manganese oxide, yttrium oxide, cerium oxide, samarium oxide, beryllium oxide, vanadium oxide, and oxide. Chromium, barium oxide, or the like was used and mixed so that the mass ratio was powder raw material: dispersant: alcohol = 65: 1: 34.

  Kerosene (Wako Pure Chemical Industries, Ltd., Kerosene (Sp. Gr. 0.78-0.79)) as a combustible material is further mixed in the alcohol mixture containing the pulverized powder raw material and dispersant, and stirred. A slurry to be a raw material for aluminum oxide was prepared. At this time, the kerosene amount [wt%] with respect to the total mass of the flammable solvent kerosene and the above-mentioned pulverized powder raw material and the alcohol mixture containing the dispersant is 0 [wt%], 15 [wt%]. , 30 [wt%], and the slurry 14a was prepared.

  Further, a high frequency voltage of about 4 MHz and about 80 kVA is applied to the high frequency oscillation coil 12b of the plasma torch 12, and a mixed gas of argon gas 40 liters / minute and oxygen 50 liters / minute is used as the plasma gas. An argon-oxygen thermal plasma flame was generated in 12. Further, the reaction temperature was controlled to be about 8000 ° C., and a spray gas of 10 liters / minute was supplied from the spray gas supply source 14 e of the raw material supply device 14.

The slurry of aluminum oxide (Al ₂ O ₃ ) was introduced into the thermal plasma flame 24 in the plasma torch 12 together with the argon gas that is the atomizing gas.

  As a result of measuring the fine particles produced as described above with an X-ray diffractometer, it was confirmed to be aluminum oxide. FIG. 4 shows the relationship between the amount of kerosene [wt%] with respect to the total mass of the powder raw material and the dispersant mixed with the pulverized powder, and the recovered amount [g / hr] of fine particles according to the present invention. The represented graph is shown.

  From the graph shown in FIG. 4, the use of kerosene in the production of fine particles increases the yield of the fine particles according to the present invention, and further, kerosene as a flammable solvent, alcohol as a dispersion medium, and the above-mentioned pulverization. It is clear that the recovery amount is increased by increasing the amount of kerosene [wt%] based on the total mass of the powder raw material and the sorbitan fatty acid ester as the dispersant.

  In addition, the particle diameter converted from the specific surface area (surface area per gram) of the aluminum oxide fine particles produced as described above was 15 nm. Further, the yield of the produced fine particles was about 50% with respect to the amount of the powder raw material charged.

[Example 2]
An embodiment in which a colloid solution is used as a raw material using the fine particle production apparatus shown in FIG. 1 will be described.

In this example, fine particles of aluminum oxide (Al ₂ O ₃ ) were produced by the method for producing fine particles according to the second embodiment. In preparing the colloidal solution, Al alkoxide was used as a raw material, and a sol-gel method was used. Ethanol was used as the solvent. As the combustible material, the same kerosene as used in Example 1 (manufactured by Wako Pure Chemical Industries, Ltd., kerosene (Sp. Gr. 0.78 to 0.79)) was used. The amount of kerosene added was 15 [wt%] in the amount of kerosene [wt%] relative to the total mass of the ethanol mixture containing the powder raw material.

The colloidal solution prepared by dispersing and mixing the fine particle production material, the solvent, and the combustible material was put into the container 14b of the raw material supply apparatus 14 shown in FIG. 1, and sufficiently stirred by the stirrer 14c.
Thereafter, fine particles were generated in the same manner as in Example 1. The driving conditions of the plasma torch were the same as in Example 1.
The average particle size of the fine particles produced in this example was 15 nm.

Example 3
An embodiment in which a solution in which a raw material is dissolved in a solvent is used as a raw material using the fine particle manufacturing apparatus shown in FIG. 1 described above will be described.

In this example, fine particles of aluminum nitrate (Al (NO ₃ ) ₃ were produced by the fine particle production method according to the third embodiment. First, aluminum nitrate, which is a metal salt, was dissolved in water, and 20 wt% An aqueous aluminum nitrate solution was prepared, and metal salts such as acetates, chlorides, hydroxides, oxalates, carbonates, and ammonium salts can be used.
As the combustible material, the same kerosene as used in Example 1 (manufactured by Wako Pure Chemical Industries, Ltd., kerosene (Sp. Gr. 0.78 to 0.79)) was used. The amount of kerosene added was 15 [wt%] in the amount of kerosene [wt%] based on the total mass of the aqueous solution containing the powder raw material.

A solution prepared by dissolving and mixing the fine particle manufacturing material aqueous solution and the combustible material was put into the container 14b of the raw material supply apparatus 14 shown in FIG. 1, and sufficiently stirred by the stirrer 14c.
Thereafter, fine particles were generated in the same manner as in Example 1. The driving conditions of the plasma torch were the same as in Example 1.
The average particle size of the fine particles produced in this example was 15 nm.

Example 4
In the fine particle manufacturing apparatus shown in FIG. 1 described above, an embodiment in which a powder raw material containing a combustible material is used as a raw material will be described using an apparatus in which the material supply apparatus is replaced with the one shown in FIG.

In this example, barium titanate (BaTiO ₃ ) fine particles, which are high-order oxide fine particles composed of a double oxide, that is, two or more kinds of oxides, were produced by the method for producing fine particles according to the fourth embodiment. Manufactured. Here, a powder raw material having a particle size of 10 μm or less was used so that barium titanate (BaTiO ₃ ) was easily evaporated in a thermal plasma flame.

As the combustible material, the same kerosene as used in Example 1 (manufactured by Wako Pure Chemical Industries, Ltd., kerosene (Sp. Gr. 0.78 to 0.79)) was used. The amount of kerosene added was 15 [wt%] in the amount of kerosene [wt%] with respect to the total mass of the combustible material including the powder raw material.
The driving conditions of the plasma torch were the same as in Example 1.
The average particle size of the fine particles produced in this example was 15 nm.

  As mentioned above, although the manufacturing method of the microparticles | fine-particles of this invention was demonstrated in detail, this invention is not limited to the said embodiment, Of course, in the range which does not deviate from the main point of this invention, a various improvement and a change may be carried out. It is.

It is a schematic diagram which shows the whole structure of the manufacturing apparatus of the fine particle for enforcing the manufacturing method of the fine particle of this invention. It is the elements on larger scale near a plasma torch. It is sectional drawing which shows schematic structure of the material supply apparatus in the case of using powder raw material as it is. It is a figure which shows the graph showing the relationship between the kerosene amount [wt%] with respect to the total mass of the powder raw material which carried out the grinding | pulverization process, and the alcohol mixed liquid containing a dispersing agent, and the collection amount [g / hr] of the microparticles | fine-particles which concern on this invention. is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fine particle manufacturing apparatus 12 Plasma torch 12a Quartz tube 12b High frequency oscillation coil 12c Plasma gas inlet 12d Inlet pipe 14 Raw material supply apparatus 14a Slurry 14b Container 14c Stirrer 14d Pump 14e Spray gas supply source 16 Chamber 18 Fine particle 20 Recovery part 20a Recovery chamber 20b Filter 20c Tube provided at upper part of recovery chamber 22 Plasma gas supply source 24 Thermal plasma flame 26 Tube 140 Raw material supply device 142 Storage tank 144 Powder raw material 146 Stirring shaft 148 Stirring blade 150a, 150b Oil seal 152a, 152b Bearing 154a, 154b Motor 160 Screw feeder 162 Screw 164 (Screw) shaft 166 Casing 170 Dispersion part 172 Outer tube 174 Dispersion chamber 176 Rotating brush 178 Air The supply port 180 gas passage 182 transport tube

Claims (18)

By introducing the fine particle production material into the thermal plasma flame, it is made a gas phase mixture,
A method for producing fine particles, characterized in that fine particles are produced by rapidly cooling the mixture in the gas phase state,
The process of introducing the fine particle production material into a thermal plasma flame,
The fine particle manufacturing material is dispersed in a combustible material to form a slurry,
A method for producing fine particles, wherein the slurry is formed into droplets and introduced into the thermal plasma flame. By introducing the fine particle production material into the thermal plasma flame, it is made a gas phase mixture,
A method for producing fine particles, characterized in that fine particles are produced by rapidly cooling the mixture in the gas phase state,
The process of introducing the fine particle production material into a thermal plasma flame,
Slurry the fine particle production material using a dispersion medium and a combustible material,
A method for producing fine particles, wherein the slurry is formed into droplets and introduced into the thermal plasma flame. By introducing the fine particle production material into the thermal plasma flame, it is made a gas phase mixture,
A method for producing fine particles, characterized in that fine particles are produced by rapidly cooling the mixture in the gas phase state,
The process of introducing the fine particle production material into a thermal plasma flame,
After dispersing the fine particle production material in a dispersion medium, further add a combustible material to make a slurry,
A method for producing fine particles, wherein the slurry is formed into droplets and introduced into the thermal plasma flame. By introducing the fine particle production material into the thermal plasma flame, it is made a gas phase mixture,
A method for producing fine particles, characterized in that fine particles are produced by rapidly cooling the mixture in the gas phase state,
The process of introducing the fine particle production material into a thermal plasma flame,
The fine particle production material is suspended in a dispersion medium to form a colloidal solution,
A method for producing fine particles, characterized in that the colloidal solution is formed into droplets and introduced into the thermal plasma flame. By introducing the fine particle production material into the thermal plasma flame, it is made a gas phase mixture,
A method for producing fine particles, characterized in that fine particles are produced by rapidly cooling the mixture in the gas phase state,
The process of introducing the fine particle production material into a thermal plasma flame,
Suspending the fine particle production material in a combustible material to form a colloidal solution,
A method for producing fine particles, characterized in that the colloidal solution is formed into droplets and introduced into the thermal plasma flame. By introducing the fine particle production material into the thermal plasma flame, it is made a gas phase mixture,
A method for producing fine particles, characterized in that fine particles are produced by rapidly cooling the mixture in the gas phase state,
The process of introducing the fine particle production material into a thermal plasma flame,
The fine particle production material is suspended in a dispersion medium and a combustible material to form a colloidal solution,
A method for producing fine particles, characterized in that the colloidal solution is formed into droplets and introduced into the thermal plasma flame. By introducing the fine particle production material into the thermal plasma flame, it is made a gas phase mixture,
A method for producing fine particles, characterized in that fine particles are produced by rapidly cooling the mixture in the gas phase state,
The process of introducing the fine particle production material into a thermal plasma flame,
After suspending the material for producing fine particles in a dispersion medium, a flammable material is further added to form a colloid solution,
A method for producing fine particles, characterized in that the colloidal solution is formed into droplets and introduced into the thermal plasma flame. By introducing the fine particle production material into the thermal plasma flame, it is made a gas phase mixture,
A method for producing fine particles, characterized in that fine particles are produced by rapidly cooling the mixture in the gas phase state,
The process of introducing the fine particle production material into a thermal plasma flame,
The fine particle production material is dissolved in a solvent to form a solution,
A method for producing fine particles, wherein the solution is made into droplets and introduced into the thermal plasma flame. By introducing the fine particle production material into the thermal plasma flame, it is made a gas phase mixture,
A method for producing fine particles, characterized in that fine particles are produced by rapidly cooling the mixture in the gas phase state,
The process of introducing the fine particle production material into a thermal plasma flame,
The fine particle manufacturing material is dissolved using a combustible material to form a solution,
A method for producing fine particles, wherein the solution is made into droplets and introduced into the thermal plasma flame. By introducing the fine particle production material into the thermal plasma flame, it is made a gas phase mixture,
A method for producing fine particles, characterized in that fine particles are produced by rapidly cooling the mixture in the gas phase state,
The process of introducing the fine particle production material into a thermal plasma flame,
The fine particle manufacturing material is dissolved in a solvent and a combustible material to form a solution,
A method for producing fine particles, wherein the solution is made into droplets and introduced into the thermal plasma flame. By introducing the fine particle production material into the thermal plasma flame, it is made a gas phase mixture,
A method for producing fine particles, characterized in that fine particles are produced by rapidly cooling the mixture in the gas phase state,
The process of introducing the fine particle production material into a thermal plasma flame,
After dissolving the fine particle production material in a solvent, further flammable material is added to form a solution,
A method for producing fine particles, wherein the solution is made into droplets and introduced into the thermal plasma flame. By introducing the fine particle production material into the thermal plasma flame, it is made a gas phase mixture,
A method for producing fine particles, characterized in that fine particles are produced by rapidly cooling the mixture in the gas phase state,
The process of introducing the fine particle production material into a thermal plasma flame,
The fine particle production material is dispersed using a carrier gas and a combustible material,
A method for producing fine particles, wherein the dispersed fine particle production material is introduced into the thermal plasma flame.   The method for producing fine particles according to any one of claims 1 to 3, 5 to 7, and 9 to 12, wherein the combustible material has an action to stabilize thermal plasma.   The fine particle production according to any one of claims 1 to 3, wherein one or a mixture of two or more selected from the group consisting of a surfactant, a polymer, and a coupling agent is added to the slurry. Method.   The fine particle according to any one of claims 4 to 7, wherein one or a mixture of two or more selected from the group consisting of a surfactant, a polymer, and a coupling agent is added to the colloid solution. Production method.   The fine particle production according to any one of claims 8 to 11, wherein one or a mixture of two or more selected from the group consisting of a surfactant, a polymer, and a coupling agent is added to the solution. Method.   13. The fine particle according to claim 12, wherein one or a mixture of two or more selected from the group consisting of a surfactant, a polymer, and a coupling agent is added to the dispersed fine particle production material. Production method.   The component constituting the fine particles includes at least one selected from the group consisting of elements of atomic numbers 3 to 6, 11 to 15, 19 to 34, 37 to 52, 55 to 60, 62 to 79, and 81 to 83. Simple oxides, complex oxides, complex oxides, oxide solid solutions, metals, alloys, hydroxides, carbonates, halides, sulfides, nitrides, carbides, hydrides, metal salts or metal organic compounds The method for producing fine particles according to claim 1.

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