JP5362614B2 - Method for producing silicon monoxide fine particles and silicon monoxide fine particles - Google Patents

Description

The present invention relates to nano-sized silicon monoxide (SiO) fine particles and a method for producing the same, and in particular, a method for producing nano-sized silicon monoxide fine particles using silicon dioxide (SiO ₂ ) as a raw material and the production method thereof. The obtained silicon monoxide fine particles.

  Currently, silicon oxide is used for a gas barrier film of a gas barrier film used for food packaging, liquid crystal display, plasma display, organic EL display, solar cell, and the like. In addition, use of silicon monoxide as a negative electrode material for lithium ion batteries has also been studied.

  For example, Patent Document 1 discloses a method for producing silicon monoxide powder. In this document, a mixed raw material powder of silicon dioxide powder having an average particle diameter of 1 μm or less and metal silicon powder having an average particle diameter of 30 μm or less is heated to 1100 to 1450 ° C. under an inert gas or reduced pressure, and silicon monoxide gas The silicon monoxide gas is deposited on the surface of the substrate to produce silicon monoxide powder.

JP 2007-290890 A

Currently, oxide fine particles, nitride fine particles, carbide fine particles, etc. are used for electrical insulation materials such as semiconductor substrates, printed boards and various electrical insulation parts, high hardness and high precision machine work materials such as cutting tools, dies and bearings, Production of functional materials such as grain boundary capacitors and humidity sensors, production of sintered bodies such as precision sintered molding materials, production of sprayed parts such as materials that require high-temperature wear resistance such as engine valves, and fuel cell electrodes It is used in fields such as electrolyte materials and various catalysts. Like the above-mentioned fine particles, silicon monoxide is also desired to be used for various purposes as fine particles.
However, the method for producing silicon monoxide powder described in Patent Document 1 does not specifically disclose the size of the obtained powder, and a specific method for producing silicon monoxide fine particles is known. The current situation is not.

  An object of the present invention is to provide a method for producing nano-sized silicon monoxide fine particles using silicon dioxide as a raw material, and silicon monoxide fine particles obtained by this production method, by solving the problems based on the conventional technology. There is.

  In order to achieve the above object, according to a first aspect of the present invention, there is provided a manufacturing method for manufacturing silicon monoxide fine particles using silicon dioxide, wherein the silicon dioxide powder is converted into a liquid substance containing carbon. Disclosed is a method for producing fine silicon monoxide particles characterized by adding water to form a slurry, making the slurry into droplets and supplying the slurry into a thermal plasma flame not containing oxygen.

In this case, the amount of the silicon dioxide powder is 10 to 65% by mass based on the total amount of the silicon dioxide powder and the liquid substance containing carbon, and the amount of the liquid substance containing carbon is The amount of water is 90 to 35% by mass with respect to the total amount of the silicon dioxide powder and the liquid substance containing carbon, and the amount of water is the total amount of the silicon dioxide powder and the liquid substance containing carbon. It is preferable that it is 10-40 mass% with respect to.
Further, for example, alcohol, ketone, kerosene, octane, or gasoline can be used as the liquid substance containing carbon.
Furthermore, the thermal plasma flame is preferably derived from at least one gas of hydrogen, helium and argon.

  Further, according to the second aspect of the present invention, a silicon dioxide powder is dispersed in a liquid substance containing carbon, and water is further added to form a slurry. The present invention provides silicon monoxide fine particles produced by being supplied into a plasma flame.

According to the present invention, nanosized silicon monoxide fine particles can be easily produced with high productivity using silicon dioxide as a raw material.
Nanosized silicon monoxide fine particles can be suitably used, for example, as a negative electrode material of a lithium ion battery.

It is a schematic diagram which shows the whole structure of the fine particle manufacturing apparatus for enforcing the manufacturing method of the silicon monoxide fine particle which concerns on embodiment of this invention. It is sectional drawing which expands and shows the plasma torch vicinity in FIG. It is sectional drawing which expands and shows the top plate of the chamber in FIG. 1, and the gas injection opening vicinity provided in this top plate. It is sectional drawing which expands and shows the cyclone in FIG. It is explanatory drawing which shows the angle of the gas injected, (a) is sectional drawing of the perpendicular direction which passes along the central axis of the top plate of a chamber, (b) is the bottom view which looked at the top plate from the downward direction. It is a graph which shows the analysis result of the crystal structure by the X ray diffraction method of the microparticles | fine-particles obtained in the Example of this invention, and the silicon monoxide for a comparison.

Hereinafter, a method for producing silicon monoxide fine particles and silicon monoxide fine particles of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
FIG. 1 is a schematic diagram showing an overall configuration of a fine particle production apparatus for carrying out a method for producing fine silicon monoxide particles according to an embodiment of the present invention. FIG. 2 is a partially enlarged view of the vicinity of the plasma torch 12 shown in FIG. 3 is an enlarged cross-sectional view showing the top plate 17 of the chamber 16 shown in FIG. 1 and the vicinity of the gas injection port 28a and the gas injection port 28b provided in the top plate 17. As shown in FIG. FIG. 4 is an enlarged cross-sectional view of the cyclone 19.

  A fine particle manufacturing apparatus 10 shown in FIG. 1 includes a plasma torch 12 that generates thermal plasma, a material supply device 14 that supplies silicon dioxide powder in a slurry state into the plasma torch 12, as will be described later, and fine particles (1 A chamber 16 having a function as a cooling tank for generating (secondary fine particles) 15; a cyclone 19 for removing coarse particles having a particle size equal to or larger than a particle size arbitrarily defined from the generated primary fine particles 15; And a recovery unit 20 that recovers silicon monoxide fine particles (secondary fine particles) 18 having a desired particle size classified by the cyclone 19.

  In the present embodiment, silicon dioxide powder (hereinafter also referred to as silicon dioxide raw material) is dispersed in a liquid substance containing carbon (hereinafter also referred to as dispersion medium), and further water is added to form a slurry. Nano-sized silicon monoxide fine particles are produced by the fine particle production apparatus 10 using the slurry.

  The plasma torch 12 shown in FIG. 2 includes a quartz tube 12a and a high-frequency oscillation coil 12b surrounding the outside. As will be described later, a supply pipe 14f for slurry 14a is provided at the center of the plasma torch 12, and a plasma gas supply port 12c is formed at the periphery (on the same circumference).

The plasma gas is sent from the plasma gas supply source 22 to the plasma gas supply port 12c (see FIG. 2).
In the present embodiment, plasma gas does not contain oxygen in order to generate carbon by decomposing without burning a liquid substance (dispersion medium) containing carbon in a thermal plasma flame 24 to be described later. Is used. Examples of the plasma gas include hydrogen, helium, and argon. The plasma gas is not limited to a single substance, and these plasma gases may be used in combination, such as hydrogen and argon or helium and argon.

  In the plasma gas supply source 22, for example, two types of plasma gases, hydrogen and argon, are prepared. 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 supply port 12c shown in FIG. Then, a high frequency voltage is applied to the high frequency oscillation coil 12b, and a thermal plasma flame 24 not containing oxygen is generated.

  The outside of the quartz tube 12a is surrounded by a concentric tube (not shown), and cooling water is circulated between the tube and the quartz tube 12a to cool the quartz tube 12a. The quartz tube 12a is prevented from becoming too hot by the thermal plasma flame 24 generated in the plasma torch 12.

  As shown in FIG. 1, the material supply apparatus 14 is connected to the upper part of the plasma torch 12 through a pipe 26 and a supply pipe 14f, and mixes silicon dioxide raw material with a liquid substance containing carbon, and further adds water. The prepared slurry 14 a is uniformly supplied from the material supply device 14 into the plasma torch 12.

  The 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 supply pipe 14f and supplying the slurry 14a into the plasma torch 12. A spray gas supply source 14e that supplies a spray gas for spraying the slurry 14a into the plasma torch 12, and a supply pipe 14f that droplets the slurry 14a and supplies the slurry 14a into the plasma torch 12.

  The spray gas subjected to the extrusion pressure is supplied from the spray gas supply source 14e together with the slurry 14a into the thermal plasma flame 24 in the plasma torch 12 through the supply pipe 14f as shown by an arrow G in FIG. The The supply pipe 14 f has a two-fluid nozzle mechanism for spraying the slurry into the thermal plasma flame 24 in the plasma torch to form droplets, whereby the slurry 14 a is converted into the thermal plasma flame 24 in the plasma torch 12. The slurry 14a can be made into droplets by spraying inside. As the atomizing gas, for example, argon, helium, hydrogen or the like is used alone or in appropriate combination. Note that the atomizing gas is not necessarily supplied.

  As described above, the two-fluid nozzle mechanism can apply a high pressure to the slurry and spray the slurry with a spray gas which is a gas, and is used as one method for forming the slurry into droplets. For example, when a nozzle having an inner diameter of 1 mm is used, if the supply pressure is 0.2 to 0.3 MPa and the slurry is flowed at 20 ml / min and the spray gas is sprayed at 10 to 20 liter / min, about 5 to 10 μm About a droplet is obtained.

  In this embodiment, the two-fluid nozzle mechanism is used, but a one-fluid nozzle mechanism may be used. As other methods, for example, a method in which slurry is dropped on a rotating disk at a constant speed and formed into droplets by centrifugal force, or a method in which a high voltage is applied to the slurry surface to form droplets is considered. It is done.

  On the other hand, as shown in FIG. 1, the chamber 16 is provided adjacent to the lower side of the plasma torch 12. The dispersion medium in the slurry 14a sprayed in the thermal plasma flame 24 in the plasma torch 12 is partly reduced by the carbon dioxide generated by being decomposed without burning in the thermal plasma flame 24, and is oxidized. Immediately thereafter, the silicon monoxide is rapidly cooled in the chamber 16 to produce primary fine particles (silicon monoxide fine particles) 15. Thus, the chamber 16 has a function as a cooling tank.

  Further, here, as one of the methods for producing silicon monoxide fine particles more efficiently, a gas supply device 28 for rapidly cooling the produced silicon monoxide fine particles is provided. Hereinafter, the gas supply device 28 will be described.

  The gas supply device 28 shown in FIGS. 1 and 3 has a predetermined direction toward the tail of the thermal plasma flame 24 (the end of the thermal plasma flame opposite to the plasma gas supply port 12c, that is, the end of the thermal plasma flame). A gas injection port 28a for injecting gas at an angle, a gas injection port 28b for injecting gas from the upper side to the lower side along the side wall of the chamber 16, and a compressor 28c for applying an extrusion pressure to the gas supplied into the chamber 16 The gas supply source 28d to be supplied into the chamber 16 and a pipe 28e for connecting them. The compressor 28c may be a blower.

As will be described in detail later, the gas ejected from the gas ejection port 28a has a cyclone together with the gas ejected from the gas ejection port 28b, in addition to the action of rapidly cooling the primary fine particles 15 generated in the chamber 16. 19 has an additional action such as contributing to the classification of the primary fine particles 15.
The above-described compressor 28c and gas supply source 28d are connected to the top plate 17 of the chamber 16 through a pipe 28e.

  Here, the gas injection port 28 b is a slit formed in the outer side top plate component 17 b of the gas supply device 28, and prevents the generated primary fine particles 15 from adhering to the inner wall portion of the chamber 16. At the same time, it is preferable to be able to inject an amount of gas capable of providing a flow velocity that can classify the primary fine particles 15 at an arbitrary classification point by the downstream cyclone 19. From the gas injection port 28b, gas is injected from the upper side to the lower side along the inner wall of the chamber 16.

  Supplyed from the gas supply source 28d (see FIGS. 1 and 3) into the top plate 17 (specifically, the outer side top plate component 17b and the upper outer side top plate component 17c) through the pipe 28e as indicated by the arrow S. The gas thus discharged is ejected from the gas ejection port 28b (also from the gas ejection port 28a, as will be described later) through the air passage provided here.

  Slurry injected into the plasma torch 12 from the material supply device 14 (in droplet form) is partially oxidized in the thermal plasma flame 24 without being burned, as will be described later. It becomes silicon. The silicon monoxide is rapidly cooled in the chamber 16 by the gas injected from the gas injection port 28a (see arrow Q), and primary particles 15 made of silicon monoxide are generated. At this time, the primary fine particles 15 are prevented from adhering to the inner wall of the chamber 16 by the gas ejected from the gas ejection port 28 b (see arrow R).

  As shown in FIG. 1, a cyclone 19 for classifying the generated primary fine particles 15 with a desired particle diameter is provided at a lower side portion of the chamber 16. As shown in FIG. 4, the cyclone 19 includes an inlet pipe 19 a that supplies the primary fine particles 15 from the chamber 16, a cylindrical outer cylinder 19 b that is connected to the inlet pipe 19 a and is located on the upper part of the cyclone 19, A truncated cone part 19c that is continuous downward from the lower part of the outer cylinder 19b and gradually decreases in diameter, and is connected to the lower side of the truncated cone part 19c, and has a coarse particle diameter that is equal to or larger than the desired particle diameter. A coarse particle recovery chamber 19d for recovering particles and an inner tube 19e connected to a recovery unit 20 described in detail later and projecting from the outer cylinder 19b are provided.

  From the inlet pipe 19a, an air flow containing the primary fine particles 15 generated in the chamber 16 is blown along the inner peripheral wall of the outer cylinder 19b. As a result, the air flow is indicated by an arrow T in FIG. By flowing from the inner peripheral wall of the outer cylinder 19b toward the truncated cone part 19c, a swirling downward flow is formed.

  The swirling downward flow is further accelerated by the inner peripheral wall of the truncated cone part 19c, and then reverses to become an upward flow and is discharged out of the system from the inner pipe 19e. A part of the airflow is reversed at the truncated cone part 19c before flowing into the coarse particle recovery chamber 19d, and is discharged out of the system from the inner pipe 19e. Centrifugal force is given to the particles by the swirling flow, and the coarse particles move in the wall direction due to the balance between the centrifugal force and the drag force. Further, the silicon monoxide fine particles separated from the air flow descend along the side surface of the truncated cone part 19c and are collected in the coarse particle collection chamber 19d. Here, the fine particles to which the centrifugal force is not sufficiently applied are discharged out of the system together with the reverse airflow at the inner peripheral wall of the truncated cone part 19c.

  Further, a negative pressure (suction force) is generated through the inner tube 19e from the collection unit 20 described in detail later. Then, by this negative pressure (suction force), the silicon monoxide fine particles separated from the above-mentioned swirling airflow are sucked as shown by an arrow U in FIG. 4 and sent to the recovery unit 20 through the inner tube 19e. It has become.

  As shown in FIG. 1, a recovery unit 20 that recovers secondary fine particles (silicon monoxide fine particles) 18 having a desired nano-size particle diameter is provided on an extension of an inner tube 19 e that is an outlet of an air flow in the cyclone 19. Is provided. 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 provided in the lower portion of the recovery chamber 20a. Yes. The fine particles sent from the cyclone 19 are drawn into the collection chamber 20a by being sucked by a vacuum pump (not shown), and are collected on the surface of the filter 20b.

  Hereinafter, while describing the operation of the fine particle production apparatus 10 configured as described above, the fine particle production apparatus 10 is used to produce the silicon monoxide fine particles according to the embodiment of the present invention, and the production method. The silicon monoxide fine particles will be described.

  Here, in this embodiment, the silicon dioxide raw material (silicon dioxide powder) is a raw material for silicon monoxide fine particles, and has an average particle diameter of 50 μm so that it can be easily evaporated in a thermal plasma flame. The average particle size is preferably 10 μm or less.

In the present embodiment, examples of the liquid substance (dispersion medium) containing carbon include alcohol, ketone, kerosene, octane, and gasoline.
Examples of the alcohol include ethanol, methanol, propanol, and isopropyl alcohol.
As described above, the liquid substance (dispersion medium) containing carbon reduces the silicon dioxide raw material. For this reason, it is preferable that the liquid substance containing carbon is easily decomposed by the thermal plasma flame 24. Therefore, the liquid substance containing carbon is preferably a lower alcohol.
Further, water (H ₂ O) is added to the slurry 14a. This water promotes the conversion of silicon dioxide material into silicon monoxide with a liquid substance (dispersion medium) containing carbon.

In the method for producing fine silicon monoxide particles of this embodiment, first, a silicon dioxide raw material is dispersed in a dispersion medium, and water is further added to obtain a slurry. In this slurry, the mixing ratio of the silicon dioxide raw material and the dispersion medium is a mass ratio, for example, 4: 6 (40%: 60%), and water is a ratio to the total amount of the silicon dioxide raw material and the dispersion medium. And 20 to 25%.
The mixing ratio of the silicon dioxide raw material and the dispersion medium and the amount of water are not limited to those described above, but the preferred range of the amount of the silicon dioxide raw material is 10 with respect to the total amount of the silicon dioxide raw material and the dispersion medium. The preferable range of the amount of the dispersion medium is 90 to 35% by mass with respect to the total amount of the silicon dioxide raw material and the dispersion medium, and the preferable range of the amount of water is that of the silicon dioxide raw material and the dispersion medium. It is 10-40 mass% with respect to the total amount.
Since the dispersion medium and water reduce silicon dioxide, the mass ratio of the silicon dioxide raw material and the dispersion medium and the amount of added water are appropriately changed so that silicon monoxide is generated. A slurry is prepared.

  Furthermore, when adjusting 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 | macromolecule, and a coupling agent. As the surfactant, for example, sorbitan fatty acid ester which is a nonionic surfactant is used. For example, ammonium polyacrylate is used as the polymer. As the coupling agent, for example, a silane coupling agent or the like is used. By adding 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 14a, the silicon dioxide raw material is more effectively aggregated with the dispersion medium and water. This prevents the slurry 14a from being stabilized.

  The slurry 14a prepared as described above is placed in the container 14b of the material supply device 14 shown in FIG. 1 and stirred by the stirrer 14c. Thereby, it is prevented that the silicon dioxide raw material in a dispersion medium precipitates, and the slurry 14a of the state by which the silicon dioxide raw material was disperse | distributed in the dispersion medium is maintained. Alternatively, the slurry 14a may be continuously prepared by supplying the material supply device 14 with a silicon dioxide raw material, a dispersion medium, and water.

  Next, the slurry 14 a is formed into droplets using the above-described two-fluid nozzle mechanism, and the slurry 14 a formed into droplets is supplied into the plasma torch 12, thereby generating heat generated in the plasma torch 12. Carbon is generated without being supplied to the plasma flame 24 and burning the dispersion medium.

The oxygen-free thermal plasma flame 24 evaporates the slurry 14a in droplets, decomposes and evaporates without burning the dispersion medium, and generates carbon. At this time, water is also decomposed into hydrogen and oxygen. Further, the thermal plasma flame 24 reduces the silicon dioxide raw material by its temperature and generated carbon, and further controls the reduction by oxygen generated from water to form silicon monoxide. For this reason, the temperature of the thermal plasma flame 24 needs to be higher than the temperature at which the silicon dioxide raw material contained in the slurry is reduced by carbon.
On the other hand, the higher the temperature of the thermal plasma flame 24, the easier the silicon dioxide raw material is reduced. However, the temperature is not particularly limited, and may be appropriately selected according to the temperature at which the silicon dioxide raw material is reduced. For example, the temperature of the thermal plasma flame 24 can be set to 6000 ° C., and it is theoretically considered to reach about 10000 ° C.

  The pressure atmosphere in the plasma torch 12 is preferably atmospheric pressure or lower. Here, the atmosphere below atmospheric pressure is not particularly limited, but may be, for example, 5 Torr to 750 Torr.

  Next, the slurry 14a evaporates in the thermal plasma flame 24 not containing oxygen, and further decomposed without burning a dispersion medium such as methanol to obtain carbon. The amount of the dispersion medium in the chiller 14a is adjusted so that more carbon is produced than the silicon dioxide raw material. The generated carbon reacts with the silicon dioxide raw material, the silicon dioxide is reduced to silicon monoxide, and the reduction is further controlled by oxygen generated from water to form silicon monoxide. The silicon monoxide generated in this manner is rapidly cooled by the gas injected in the direction indicated by the arrow Q through the gas injection port 28a, and is rapidly cooled in the chamber 16 to be made of silicon monoxide. Primary fine particles 15 are obtained.

  Accordingly, the amount of gas injected from the gas injection port 28a needs to be a supply amount sufficient for rapidly cooling the silicon monoxide fine particles in the process of generating the primary fine particles. Combined with the amount of gas injected from the injection port 28b, and further with the amount of gas supplied into the thermal plasma flame described later, a flow velocity capable of classifying the primary fine particles 15 at an arbitrary classification point by the downstream cyclone 19 is obtained. And an amount that does not hinder the stability of the thermal plasma flame.

  Note that the combined amount of gas injected from the gas injection port 28a and the amount of gas injected from the gas injection port 28b is 200% to 5000% of the gas supplied into the thermal plasma flame. It is good to do. Here, the gas supplied into the above-mentioned thermal plasma flame is a combination of a plasma gas that forms a thermal plasma flame, a central gas that forms a plasma flow, and a spray gas.

  Further, the supply method and supply position of the injected gas are not particularly limited as long as the stability of the thermal plasma flame is not hindered. In the fine particle manufacturing apparatus 10 of the present embodiment, a gas is injected by forming a circumferential slit in the top plate 17, but a method that can reliably supply gas on the path from the thermal plasma flame to the cyclone. Other methods and positions may be used as long as they are positions.

  The primary fine particles 15 made of silicon monoxide finally generated in the chamber 16 are blown from the inlet pipe 19a of the cyclone 19 along the inner peripheral wall of the outer cylinder 19b together with the air current. 4 flows along the inner peripheral wall of the outer cylinder 19b as indicated by the arrow T in FIG. Then, this swirling flow is further accelerated at the inner peripheral wall of the truncated cone part 19c, then reverses, becomes an upward flow, and is discharged out of the system from the inner pipe 19e. A part of the airflow is reversed at the inner peripheral wall of the truncated cone part 19c before flowing into the coarse particle recovery chamber 19d, and is discharged out of the system from the inner pipe 19e.

  Centrifugal force is applied to the primary fine particles 15 made of silicon monoxide by a swirl flow, and coarse particles of the primary fine particles 15 move in the wall direction due to the balance between centrifugal force and drag force. Further, among the primary fine particles 15, particles separated from the air flow descend along the side surface of the truncated cone part 19c and are collected in the coarse particle collection chamber 19d. Here, the fine particles to which the centrifugal force is not sufficiently applied are discharged out of the system as silicon monoxide fine particles (secondary fine particles) 18 from the inner tube 19e together with the reverse airflow on the inner peripheral wall of the truncated cone part 19c. The flow velocity of the airflow into the cyclone 19 at this time is preferably 10 m / sec or more.

The discharged silicon monoxide fine particles (secondary fine particles) 18 are sucked by a negative pressure (suction force) from the collecting unit 20 as shown by an arrow U in FIG. 4, and are sent to the collecting unit 20 through the inner tube 19e. And collected by the filter 20b of the collection unit 20. At this time, the internal pressure in the cyclone 19 is preferably not more than atmospheric pressure. In addition, the particle size of the silicon monoxide fine particles (secondary fine particles) 18 is defined as an arbitrary particle size at the nano-size level according to the purpose.
Thus, in this embodiment, nanosized silicon monoxide fine particles can be obtained.
In the method for producing silicon monoxide fine particles of the present invention, the number of cyclones used is not limited to one, and may be two or more.

  The silicon monoxide fine particles produced by the method for producing silicon monoxide fine particles according to the present embodiment have a narrow particle size distribution width, that is, a uniform particle size and almost no inclusion of coarse particles of 1 μm or more. Specifically, it is nano-sized silicon monoxide fine particles having an average particle diameter of 1 to 100 nm.

The silicon monoxide fine particles obtained by the method for producing silicon monoxide fine particles of the present embodiment can be used for, for example, a negative electrode material of a lithium ion battery.
In addition, the silicon monoxide fine particles obtained by the method for producing silicon monoxide fine particles of the present embodiment are, for example, for various optics, antireflection films, absorption films, protective films, protective insulating films for liquid crystal conductive films, and semiconductor element protections. It can also be used for films, dielectrics for thin film capacitors, antireflection films such as solar cells, and vapor deposition materials for gas barrier films.

  Moreover, in this embodiment, since a liquid is used for the carbon source used for the reduction | restoration of a silicon dioxide raw material, and others are water, a silicon dioxide raw material can be supplied uniformly with respect to a thermal plasma flame easily. . Furthermore, since the carbon source is a liquid, it is easily decomposed as compared with a solid carbon source such as graphite, and the silicon dioxide raw material can be efficiently reacted with carbon. Thereby, the reaction efficiency with respect to silicon monoxide of a silicon dioxide raw material becomes high, and silicon monoxide microparticles | fine-particles can be manufactured with high productivity.

  Further, in the method for producing silicon monoxide fine particles of the present embodiment, the fine particles can be classified with a cyclone provided in the apparatus by supplying a gas and arbitrarily controlling the flow rate in the apparatus. In the method for producing fine silicon monoxide particles according to the present embodiment, coarse particles can be separated at an arbitrary classification point by changing the gas flow rate or the cyclone inner diameter without changing the reaction conditions. Thus, high-quality fine particles with high quality can be produced with high productivity.

  Furthermore, in the manufacturing method of the silicon monoxide fine particles according to the present embodiment, since the swirl flow is generated in the cyclone, the residence time becomes long and the fine particles are cooled in the cyclone. There is no need to provide a road. Therefore, it is not necessary to stop the operation of the apparatus for removing the fine particles accumulated in the fins, and the operation time of the apparatus can be extended. Furthermore, the cooling effect can be further enhanced by employing a water-cooled jacket structure for the entire cyclone.

  As described above, the fine particle production apparatus 10 of the present embodiment is characterized by including the gas supply device 28 whose main purpose is to rapidly cool the gas phase mixture. Hereinafter, the gas supply device 28 will be additionally described.

The gas supply device 28 shown in FIG. 1 and FIG. 3 has a gas injection port 28 a for injecting gas at a predetermined angle as described above toward the tail of the thermal plasma flame 24, and the upper side along the side wall of the chamber 16. The gas injection port 28b that injects the gas downward, the compressor 28c that applies an extrusion pressure to the gas supplied into the chamber 16, and the gas supply source 28d that is supplied into the chamber 16 are connected to each other. And a tube 28e.
The compressor 28c and the gas supply source 28d are connected to the top plate 17 of the chamber 16 through a pipe 28e. Here, the tail part of the thermal plasma flame is the end of the thermal plasma flame opposite to the plasma gas supply port 12c, that is, the terminal part of the thermal plasma flame.

  As shown in FIG. 3, the gas injection port 28 a and the gas injection port 28 b are formed in the top plate 17 of the chamber 16. Here, the top plate 17 includes an inner top plate component 17a having a truncated cone shape and a part of the upper side being a cylinder, an outer top plate component 17b having a truncated cone-shaped hole, and an inner top plate component 17a. And an upper outer part top plate component 17c having a moving mechanism for moving it vertically.

  Here, a screw is cut at a portion where the inner side top plate component 17a and the upper outer side top plate component 17c are in contact (in the inner side top plate component 17a, the upper cylindrical portion), and the inner top plate component 17a is By rotating, the position can be changed in the vertical direction, and the inner top plate component 17a can adjust the distance from the outer top plate component 17b. In addition, the gradient of the truncated cone part of the inner top plate part 17a and the gradient of the truncated cone part of the hole of the outer part top plate part 17b are the same, and are structured to engage with each other.

  Further, the gas injection port 28a is formed in a circumferential shape that can adjust a gap formed by the inner top plate component 17a and the outer top plate component 17b, that is, a slit width, and is concentric with the top plate. Is a slit. Here, the gas injection port 28a may be any shape that can inject gas toward the tail of the thermal plasma flame 24, and is not limited to the slit shape as described above. A large number of holes may be provided.

  Further, an air passage 17d through which a gas sent through the pipe 28e passes is provided inside the upper outer portion top plate component 17c. The gas passes through the air passage 17d and is sent to the gas injection port 28a which is a slit formed by the inner top plate component 17a and the outer top plate component 17b described above. As described above, the gas sent to the gas injection port 28a is directed in the direction indicated by the arrow Q in FIGS. 1 and 3 toward the tail portion (terminal portion) of the thermal plasma flame. It is injected at an angle of.

  Here, the predetermined supply amount will be described. As described above (see paragraph 0045), the amount produced to quench the gas phase mixture is, for example, supplied into the chamber that forms the space necessary to quench the gas phase mixture. The average flow velocity (in-chamber flow velocity) of the gas in the chamber 16 is preferably 0.001 to 60 m / sec, and more preferably 0.5 to 10 m / sec. This is a gas supply amount sufficient to rapidly cool the gas phase mixture sprayed and evaporated in the thermal plasma flame 24 to generate fine particles, and to prevent aggregation due to collision between the generated fine particles.

Note that this supply amount is sufficient to rapidly cool and solidify the gas phase mixture, and to prevent agglomeration due to collision between the microparticles immediately after solidification and formation. The amount needs to be sufficient to dilute the mixture, and the value may be appropriately determined according to the shape and size of the chamber 16.
However, this supply amount is preferably controlled so as not to hinder the stability of the thermal plasma flame.

  Next, the predetermined angle in the case where the gas injection port 28a has a slit shape will be described with reference to FIGS. FIG. 5A shows a vertical cross-sectional view passing through the central axis of the top plate 17 of the chamber 16, and FIG. 5B shows a view of the top plate 17 as viewed from below. FIG. 5B shows a direction perpendicular to the cross section shown in FIG. Here, a point X shown in FIGS. 5A and 5B indicates that the gas sent from the gas supply source 28d (see FIG. 1) via the air passage 17d is introduced into the chamber 16 from the gas injection port 28a. It is an injection point to be injected. Actually, since the gas injection port 28a is a circumferential slit, the gas at the time of injection forms a belt-like airflow. Therefore, the point X is a virtual emission point.

  As shown in FIG. 5 (a), the center of the opening of the air passage 17d is the origin, the vertical upward is 0 °, the positive direction is counterclockwise on the page, and the gas injection port is in the direction indicated by the arrow Q. The angle of the gas injected from 28a is represented by angle α. This angle α is an angle with respect to the direction from the first part of the thermal plasma flame to the tail part (terminal part) described above.

  Further, as shown in FIG. 5B, the thermal plasma flame with the virtual injection point X as the origin and the direction toward the center of the thermal plasma flame 24 as 0 ° and the counterclockwise direction on the paper as the positive direction. The angle of the gas ejected from the gas ejection port 28a in the direction indicated by the arrow Q in the plane direction perpendicular to the direction from the initial part 24 to the tail part (terminal part) is represented by an angle β. This angle β is an angle with respect to the central portion of the thermal plasma flame in the plane perpendicular to the direction from the initial portion to the tail portion (terminal portion) of the thermal plasma flame described above.

  Using the angle α (usually the vertical angle) and the angle β (usually the horizontal angle) described above, the predetermined angle, that is, the supply direction of the gas into the chamber, , The angle α is 90 ° <α <240 ° (preferably in the range of 100 ° <α <180 °, more preferably α = 135 °) with respect to the tail (end portion) of the thermal plasma flame 24, and the angle β. Is −90 ° <β <90 ° (preferably in a range of −45 ° <β <45 °, more preferably β = 0 °).

  As described above, the gas phase mixture is rapidly cooled by the gas injected toward the thermal plasma flame 24 at a predetermined supply amount and a predetermined angle, and fine particles 15 are generated. The gas injected into the chamber 16 at the predetermined angle described above does not necessarily reach the tail of the thermal plasma flame 24 at the injected angle due to the influence of turbulent flow generated inside the chamber 16. In order to effectively cool the mixture in the phase state, stabilize the thermal plasma flame 24, and operate the fine particle production apparatus 10 efficiently, it is preferable to determine the angle. The angle may be determined experimentally in consideration of conditions such as the size of the apparatus and the size of the thermal plasma flame.

  If fine particles immediately after generation collide with each other and aggregates are formed, resulting in non-uniform particle size, it becomes a cause of quality deterioration. On the other hand, in the method for producing silicon monoxide fine particles of the present invention, the gas plasma outlet 28a is passed through the gas injection port 28a at a predetermined angle and supply amount in the direction indicated by the arrow Q toward the tail (end portion) of the thermal plasma flame. The injected gas dilutes the fine particles 15 to prevent the fine particles from colliding and aggregating. That is, the gas injected from the gas injection port 28a rapidly cools the gas phase mixture, and further prevents the generated silicon monoxide fine particles from agglomerating, thereby reducing the particle diameter of the silicon monoxide fine particles. , And both sides of uniformizing the particle size of the silicon monoxide fine particles.

  By the way, the gas injected from the gas injection port 28 a has a considerable adverse effect on the stability of the thermal plasma flame 24. However, in order to continuously operate the entire apparatus, it is necessary to stabilize the thermal plasma flame. For this reason, the gas injection port 28a in the fine particle manufacturing apparatus 10 of the present embodiment is a circumferentially formed slit, and the amount of gas supply can be adjusted by adjusting the slit width. Since a uniform gas can be injected in the central direction, it can be said that it has a preferable shape for stabilizing the thermal plasma flame. This adjustment can also be performed by changing the supply amount of the injected gas.

  As described above, the method for producing silicon monoxide fine particles and the silicon monoxide fine particles 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 modifications can be made without departing from the gist of the present invention. Of course, you may do it.

Examples of the method for producing silicon monoxide fine particles of the present invention will be specifically described below.
In this example, the production of silicon monoxide fine particles was attempted by using the above-mentioned fine particle production apparatus 10 using the slurry of “raw material mixture ratio” in each of Experimental Examples 1 to 5 shown in Table 1 below.

As raw materials for silicon monoxide fine particles, the slurry of each of Experimental Examples 1 to 5 contained silicon dioxide powder and alcohol as shown in the “raw material mixing ratio” column of Table 1 below, and water was added. Some are not added.
In addition, the numerical value of the silicon dioxide powder and alcohol shown in the column of “Raw material mixing ratio” indicates the mass ratio of the silicon dioxide powder and alcohol. The numerical value of water indicates the ratio of the amount of water to the total amount of powder of silicon dioxide and alcohol.
The silicon dioxide powder used as the raw material has an average particle size of 4 μm. Ethanol was used as the alcohol.

  Here, 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 the plasma gas shown in the following Table 1 is supplied from the plasma gas supply source 22 for each embodiment. Then, a thermal plasma flame was generated in the plasma torch 12. In addition, argon gas was supplied at 10 liters / min from the spray gas supply source 14e of the material supply apparatus 14 as the spray gas.

In this example, the slurries of Experimental Examples 1 to 5 were supplied into the thermal plasma flame 24 in the plasma torch 12 together with the argon gas that is the atomizing gas.
Further, argon gas or a mixed gas of argon and helium was used as the gas supplied into the chamber 16 by the gas supply device 28. The flow rate in the chamber at this time was 5 m / sec, and the supply amount was 1 m ³ / min.
The pressure in the cyclone 19 was 50 kPa, and the supply speed of fine particles from the chamber 16 to the cyclone 19 was 10 m / sec (average value).

The ratio of hydrogen gas, helium gas, and argon gas in the plasma gas of the thermal plasma flame was such that the amount of hydrogen gas was 0 to 20 vol% with respect to the total amount of helium gas and argon gas.
In addition, when the plasma gas is two types of hydrogen gas and helium gas, the amount of hydrogen gas is 0 to 20 vol% with respect to the total amount of helium gas, and when two types of hydrogen gas and argon gas are used, the total amount of argon gas is On the other hand, the amount of hydrogen gas was set to 0 to 20 vol%.
The supply amount of plasma gas was 10 to 300 liter / min for argon gas and 5 to 30 liter / min for helium gas.

  Next, in Experimental Examples 1 to 5 shown in Table 1 below, the crystal structures of the obtained products were examined using X-ray diffraction (XRD). The result is shown in FIG. In FIG. 6, reference symbol A indicates the result of X-ray diffraction (XRD) of commercially available silicon monoxide.

Among Experimental Examples 1 to 5, as shown in FIG. 6, in Experimental Example 3 in which the amount of water is 20% and Experimental Example 4 in which the amount of water is 25%, silicon carbide (SiC) is hardly generated. Silicon monoxide was obtained, and the particle size was about 17 nm.
On the other hand, since Experimental Example 1 did not add water, silicon carbide was obtained with almost no silicon monoxide produced. In Experimental Example 2 and Experimental Example 5, silicon carbide was also generated in addition to silicon monoxide.

DESCRIPTION OF SYMBOLS 10 Fine particle manufacturing apparatus 12 Plasma torch 12a Quartz tube 12b High frequency oscillation coil 12c Plasma gas supply port 14 Material supply apparatus 14a Slurry 14b Container 14c Stirrer 14d Pump 14e Spray gas supply source 14f Supply pipe 15 Primary particle 16 Chamber 17 Top plate 17a Inner part top plate component 17b Outer part top plate component 17c Upper outer part top plate component 17d Air passage 18 Fine particles (secondary fine particles)
19 Cyclone 19a Inlet tube 19b Outer tube 19c Frustum 19d Coarse particle recovery chamber 19e Inner tube 20 Recovery unit 20a Recovery chamber 20b Filter 20c Tube 22 Plasma gas supply source 24 Thermal plasma flame 26 Tube 28 Gas supply device 28a Gas injection port 28b Gas injection port 28c Compressor 28d Gas supply source 28e Pipe

Claims (5)

A method for producing silicon monoxide fine particles using silicon dioxide,
Disperse the silicon dioxide powder in a liquid substance containing carbon, add water to make a slurry,
A method for producing silicon monoxide fine particles, wherein the slurry is made into droplets and supplied into a thermal plasma flame not containing oxygen. The amount of the silicon dioxide powder is 10 to 65% by mass with respect to the total amount of the liquid substance containing the silicon dioxide powder and the carbon,
The amount of the liquid substance containing carbon is 90 to 35% by mass with respect to the total amount of the silicon dioxide powder and the liquid substance containing carbon,
2. The method for producing silicon monoxide fine particles according to claim 1, wherein an amount of the water is 10 to 40 mass% with respect to a total amount of the liquid substance containing the silicon dioxide powder and the carbon.   The method for producing fine silicon monoxide particles according to claim 1 or 2, wherein the liquid substance containing carbon is alcohol, ketone, kerosene, octane or gasoline.   The method for producing fine silicon monoxide particles according to any one of claims 1 to 3, wherein the thermal plasma flame is derived from at least one gas of hydrogen, helium and argon.   It was generated by dispersing silicon dioxide powder in a liquid substance containing carbon, adding water to make a slurry, and making the slurry into droplets and supplying them into a thermal plasma flame containing no oxygen Silicon monoxide fine particles characterized by

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