JPH06247712A - Method and apparatus for producing fine ceramic particles - Google Patents

Abstract

(57) [Summary] [Structure] One kind or a plurality of kinds of metal compounds are vaporized into a raw material gas, and the raw material gas is made into a carrier gas.
The raw material is fed into a reaction space provided in an annular portion between the inner and outer cylinders of a coaxial double-cylindrical reactor having a stationary outer cylinder and a rotatable inner cylinder, and the raw material is supplied in the reaction space while rotating the inner cylinder. A method and apparatus for producing fine ceramic particles, characterized by reacting a gas. [Effect] According to the present invention, as a flow of the CVD reaction field,
By adopting the Taylor vortex flow, the temperature distribution in the vortex flow, the reaction gas concentration distribution, and the residence time of the produced fine particles trapped in the vortex flow become uniform, and it is possible to obtain uniform fine particles with high yield. . Further, by supplying the nuclear fine particles to the reaction space and supplying the raw material gas to the reaction space from two or more supply ports, it is possible to obtain the multi-layer structure fine particles in which the thickness of each layer is uniform in a high yield.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing fine ceramic particles and an apparatus therefor. More specifically, one or more kinds of metal compounds are vaporized into a raw material gas, and a chemical reaction of the raw material gas, that is, a CVD method (Chemic
al Vapor Deposition; vapor phase chemical growth method) and a method for continuously producing fine ceramic particles.

[0002]

2. Description of the Related Art Generally, ceramic fine particles include TiO ₂ , ZnO and Al.
There are fine particles of oxides such as ₂ O ₃ and SiO ₂ , carbides such as SiC and TiC, and nitrides such as Si ₃ N ₄ , TiN and AlN, but their photoconductivity, piezoelectricity, fluorescence and catalytic effect. It is frequently used in various industrial fields by taking advantage of its performance.

Among the ceramic fine particles, for example, titanium oxide fine particles have a wide range of industrial product values and are used as white pigments, magnetic raw materials, abrasives, pharmaceuticals, and ultraviolet shielding materials. Further, for example, SiC fine particles also have a wide range of industrial product values, and are used as thermistors by utilizing their resistance stability and as varistors by utilizing the non-linearity of voltage-current. Other ceramic fine particles also have various industrial values. As described above, ceramic fine particles have an extremely high industrial value, but in order to maximize their functions, it is important to make fine fine particles having a narrow particle diameter distribution width. That is, by making the particles fine, the specific surface area is increased, and the ratio of the number of molecules located on the surface of the particles to the total number of molecules constituting the particles is increased. The function is extremely greatly expressed, and since the particle size distribution width is narrow, there is no variation in the function expression.
Further, when the ceramic fine particles are concentrically formed into a multilayer structure, it is possible to combine the functions of the ceramics constituting each layer and to improve the surface properties of the substance serving as the core. In order to maximize the function of such multi-layer structure fine particles, it is necessary to uniformly deposit each layer constituting the ceramic fine particles. In particular, by uniformly and evenly depositing the outermost surface layer, it is possible to prevent the surface properties of the inner layer from directly reaching the outside and to evenly develop the properties of the outermost surface layer.

The above-mentioned methods for producing ceramic fine particles having extremely important industrial value are roughly classified into a liquid phase method and a vapor phase method. In the liquid phase method, for example, in the production of zinc oxide fine particles, a method of hydrolyzing those metal alkoxides to obtain zinc oxide fine particles (JP-A-2-59425).
Issue gazette). In general, there has been a method for obtaining desired ceramic fine particles by adding an acid / alkali solution to a metal salt and causing a reaction in a liquid phase. Regarding the multi-layered structure fine particles, for example, a method is known in which a metal salt is added to a suspension aqueous solution of TiO ₂ fine particles and the surface of the fine particles is coated with a metal oxide by a neutralization reaction (JP-A-3-88877). There is. Regarding the manufacturing process by the liquid phase method, it is difficult to automate it because it is basically a batch system, and since the produced fine particles can be obtained in a solid-liquid mixed phase, filtration and drying steps must be added to obtain the product. However, the whole manufacturing process becomes complicated, and it is difficult to maintain the whole process. Therefore, it becomes difficult to reduce the cost of the product.

In the vapor phase method, generally, a method of vaporizing a metal, mixing the vapor and a gas containing oxygen to cause a catalytic oxidation reaction to obtain fine ceramic particles (for example, in the production of fine zinc oxide particles, There are JP-A 1-286919 and JP-A 2-208369). Further, as one method of the vapor phase method, there is a method for producing fine particles called a CVD method (vapor phase chemical growth method), which introduces a source gas together with a carrier gas into a reaction tube to heat the source gas internally. In this method, fine particles are obtained by giving a chemical reaction by applying energy by the same method, and the high product purity and relatively uniform particle diameter can be mentioned. For example, a method of producing an amorphous spherical silica powder by a CVD method using an organic silicon compound as a raw material (Japanese Patent Laid-Open No. 4-97907), a fluidized bed of fine particles is formed by using a low-frequency synthetic sound wave, and CV is formed on the fluidized bed.
There is a method (Japanese Patent Application Laid-Open No. 64-80437) in which coating is performed using the D method to produce coated fine particles.

As a method having the characteristics of both the liquid phase method and the gas phase method, there is a spray pyrolysis method, which atomizes an aqueous solution containing an inorganic acid salt or an organic acid salt of a metal or an organic solvent solution, This is a method of transporting the atomized liquid particles to a heating furnace to obtain oxide-based fine particles by a thermal decomposition reaction (for example, in the production of oxide-based superconductors, Japanese Patent Laid-Open No. 2-196023).

The above vapor phase method or one of the methods, C
In the VD method and the spray pyrolysis method which is a modification thereof,
Generally, in a reactor for producing fine particles, in order to control the particle size and crystallinity of the produced fine particles, a straight pipe is used so that the temperature distribution, the raw material gas concentration distribution, or the raw material droplet density distribution inside the reactor becomes uniform. The raw material gas is made to flow in a laminar flow in the mold reactor to produce fine particles. Therefore, when the reactor is scaled up, it is difficult to make the temperature distribution, the raw material gas concentration distribution, or the raw material droplet density distribution uniform inside the reactor, which makes it difficult to scale up the reactor. ,
The problem is that the yield is low because a large amount of fine particles adhere to the inner wall of the reactor.

On the other hand, in the case of liquid-liquid reaction, a method of obtaining uniform droplets by utilizing Taylor vortex flow is disclosed in JP-A-56-139122. Here, the Taylor vortex flow is a donut-shaped vortex flow that appears in the fluid when the double cylinders sharing the central axis are filled with the fluid, the outer cylinder is stationary, and the inner cylinder is rotated at a certain rotation speed or more.
The Taylor vortex flows are regularly arranged in the axial direction of the cylinder, and by appropriately setting the liquid phase flow velocity in the axial direction, the Taylor vortex flows move in parallel while being aligned in one line without disappearing. If such Taylor vortex flow is used, it is considered that the reactor can be easily scaled up and continuous reaction is possible, but there is no example used in the gas phase method. The production of uniform droplets in a liquid-liquid system using the Taylor vortex flow and its application to the liquid-liquid reaction are described in the above-mentioned JP-A-56-139122, but a ceramic using the Taylor vortex flow is used. The method for producing fine particles is not yet known.

[0009]

The present invention has been made to solve the problems such as the difficulty of scale-up and the low yield in the vapor phase method described above. It is possible to mass-produce ceramic fine particles with high yield because the reactor can be easily scaled up, continuous operation can be performed, and the adhesion of fine particles to the inner and outer cylindrical wall surfaces is small. Was discovered and further research was conducted to complete the present invention.

That is, the gist of the present invention is (1) one type,
Alternatively, by vaporizing a plurality of types of metal compounds into a raw material gas,
The raw material gas is supplied by a carrier gas to a reaction space provided in an annular portion between the inner and outer cylinders of a coaxial double cylindrical reactor having a stationary outer cylinder and a rotatable inner cylinder, and the inner cylinder is rotated. While producing the ceramic fine particles characterized by reacting the raw material gas in the reaction space, (2) in addition to the raw material gas, core fine particles are further supplied to the reaction space by a carrier gas to react the raw material gas. The surface of the core fine particles is coated with the resulting ceramics. (3) The manufacturing method according to (1) above, and (3) the two or more supply ports provided in the coaxial double cylindrical reactor, Characteristically, different raw material gases are supplied to the reaction space by the carrier gas, and ceramics fine particles having a multi-layered structure are formed by the ceramics produced by the reaction of each raw material gas. (1) or (2) above, (4) The rotation speed of the inner cylinder is controlled so as to form a Taylor vortex flow in the gas in the reaction space, (1) to (3) above The manufacturing method according to any one of
(5) The Taylor number and the Reynolds number represented by the following equations are 40 to 15,000 and 0.05 to 2,0, respectively.
The rotation angular velocity of the inner cylinder and the axial velocity of the gas phase are controlled so as to be in the range of 00.
(4) The manufacturing method according to any one of the above, Ta = (Ri.ω.d / ν) (d / Ri) ^1/2 Re = d ・ u / ν (wherein Ta is the Taylor number and Ri is the inner cylinder) The diameter, ω is the rotational angular velocity of the inner cylinder, Re is the Reynolds number, d is the width of the annular portion between the inner and outer cylinders, ν is the kinematic viscosity of the gas phase, and u is the axial velocity of the gas phase.) (6) One A raw material vaporizer for vaporizing a raw material gas by vaporizing one or more kinds of metal compounds, a carrier gas supply device for transporting the raw material gas, a stationary outer cylinder for forming a Taylor vortex and a rotatable inner A coaxial double-cylindrical reactor having a cylinder and a source gas supply port, a device for driving an inner cylinder to rotate the inner cylinder, and an energy necessary for a chemical reaction in an annular portion between the inner and outer cylinders. Energy supply device for supplying into the reaction space provided, and the reaction An apparatus for producing ceramic fine particles, comprising: a fine particle collecting device for collecting fine particles in a gas phase emerging from a space; and (7) a coaxial double cylindrical reactor having a nuclear fine particle supply port. (6), which is further provided and is connected to a means for supplying fine nuclear particles.
The manufacturing apparatus described above.

The present invention will be described in detail below with reference to the drawings. The ceramic fine particles of the present invention have two modes, one having a single layer and one having a multilayer structure, and there are various modes for an apparatus for producing them. FIG. 1 is a schematic view of an example of an apparatus for producing ceramic fine particles having a single layer. In FIG. 1, the raw material gas consisting of one kind or a plurality of kinds of metal compounds vaporized by the raw material vaporization device 5 is stopped by the carrier gas supplied from the carrier gas supply device 6 and the stationary outer cylinder 2
Then, it is introduced into a coaxial double-cylindrical reactor having a rotatable inner cylinder 1 through a raw material supply port 9 provided at the bottom of the apparatus. At this time, the inner cylinder is rotated by the inner cylinder rotation driving device 3, and the rotation speed of the inner cylinder and the axial velocity of the gas phase are appropriately set in the gap (reaction space 8) between the inner cylinder 1 and the outer cylinder 2. The Taylor vortex, which is an annular gas-phase vortex, is formed, and this Taylor vortex is in a gas-gas mixed state at the inlet, but the raw material gas contained in this Taylor vortex is moving while moving toward the outlet. Receives energy from an energy supply device 4 which supplies energy necessary for a chemical reaction, causes a chemical reaction, and produces fine ceramic particles. The fine particles in the gas phase that have exited from the reaction space 8 are collected by the fine particle collector 7.

The raw material vaporizer is preferably an evaporator type having a temperature controllable heating element, and in particular, one capable of keeping the amount of raw material evaporated constant.

The carrier gas supply device is capable of supplying a carrier gas at a constant flow rate for a long time, and a mass flow meter, for example, can be used as the flow rate control device.

The coaxial double-cylindrical reactor comprises a stationary outer cylinder and a rotatable inner cylinder, and an annular portion which is a gap between the inner cylinder and the outer cylinder is used as a reaction space. As the material of the device, for example, stainless steel, ceramics, quartz glass or the like can be used.

The device for driving the inner cylinder rotation is such that the inner cylinder can be constantly rotated for a long time, and for example, an inverter-controlled motor or the like can be used.

As the energy supply device necessary for the chemical reaction, heat, light, plasma, etc. generators are used for each process of thermal CVD, photo CVD and plasma CVD. More specifically, a high-temperature heating element (electric furnace, etc.) capable of controlling temperature, a low-pressure mercury lamp, CO ₂ , ArF, etc.
It is a generator for laser, arc plasma, high frequency induction heating plasma, etc.

As an example of these reactions, Ti (OC ₃ H ₇ ) ₄ → TiO ₂ + 4C ₃ H ₆ + 2H ₂ O (thermal CVD) (Si (CH ₃ ) ₃ ) ₂ NH → Si ₂ NC ₆ H ₁₉ ( Photo CVD) SiH ₄ + N ₂ → SiN ₂ H ₄ (plasma CVD) and the like.

As for the energy distribution in the reaction space, it is preferable that the temperature distribution in the reaction space can be made uniform in the case of thermal CVD, and the uniform light field can be obtained in the photo CVD and the plasma CVD. And the plasma field is good.

As the fine particle collecting device, a filter type, an electrostatic collecting type and the like are effective, but an electrostatic collecting type such as an electrostatic precipitator or a diffusion charging type is preferable for long-term operation.

Next, an apparatus for producing ceramic fine particles having a multilayer structure will be described. The following three modes can be mentioned for producing ceramic fine particles having a multilayer structure. First, FIG. 2 shows a schematic view of an example of the apparatus of the first aspect for producing ceramic fine particles having a multilayer structure according to the present invention. In FIG. 2, an inner cylinder 1, an outer cylinder 2, an inner cylinder rotation drive device 3, an energy supply device 4, a raw material vaporization device 5, a carrier gas supply device 6, a reaction space 8 and a Taylor vortex flow are formed in the reaction space by these. The mechanism for chemically reacting the raw material gas is the same as in the case of FIG. 1 described above. In the present apparatus, the coaxial double-cylindrical reactor is further provided with a nuclear fine particle supply port 12 and is connected to a nuclear fine particle supply means. That is, the term "nucleus fine particle supply means" as used herein means a fine particle substance (hereinafter referred to as the core of ceramic fine particles) in the carrier gas supplied from the carrier gas supply device 11 for powder transportation, using the powder supply / dispersion device 10. , Nuclear fine particles) and introduces a carrier gas containing the nuclear fine particles into the reaction space 8 from the nuclear fine particle supply port 12. In this embodiment, the raw material gas is introduced from the raw material gas supply port 9 provided at the top of the coaxial double cylindrical reactor,
The ceramics generated by the chemical reaction of the raw material gas adhere to the surface of the nuclear fine particles introduced from the supply port 12, whereby the ceramics fine particles having a multi-layer structure are generated. The fine particles in the gas phase that have come out of the reaction space 8 are the same as those shown in FIG.
In the same manner as in the above case, the particles are collected by the fine particle collection device 7. The nuclear fine particle supply port 12 is usually provided near the inlet of the reaction space.

The carrier gas supply device for powder transportation may be any device capable of supplying the carrier gas at a constant flow rate for a long time, like the carrier gas supply device, and is composed of a carrier gas supply source and a flow rate control device. It Of these, the carrier gas supply source may be the same as the carrier gas supply device. The powder supply / dispersion device may be any device that can uniformly disperse the core fine particles in the carrier gas at a constant concentration. For example, a powder storage tank is provided, and the core is supplied at a constant speed. Examples include a method in which fine particles are passed through a narrow tube at high speed by a carrier gas to disperse nuclear fine particles in the carrier gas.

FIG. 3 is a schematic view showing an example of an apparatus of the second aspect for producing ceramic fine particles having a multilayer structure according to the present invention. In FIG. 3, the inner cylinder 1,
The outer cylinder 2, the inner cylinder rotation driving device 3, the energy supply device 4, the raw material vaporization devices 5a and 5b, the carrier gas supply devices 6a and 6b, the reaction space 8 and a Taylor vortex flow are formed in the reaction space by these, and the raw material gas The mechanism for chemically reacting is similar to that in the case of FIG. 1 described above. The apparatus of FIG. 1 has one source gas supply port, but the apparatus of FIG. 3 is different in that two source gas supply ports (9a, 9b) are provided. In this aspect, the source gas supply port 9a provided at the bottom of the apparatus
The raw material gas is further introduced, and on the surface of the ceramic produced by the chemical reaction of the raw material gas, the ceramic produced by the chemical reaction of another raw material gas introduced through the supply port 9b provided in the outer cylindrical wall of the apparatus is By depositing, fine ceramic particles having a multilayer structure are produced. Since different kinds of raw material gas are introduced from the respective supply ports, a multi-layer structure corresponding to the kind of raw material gas can be obtained. Although FIG. 3 exemplifies the case where the source gas supply ports are two, the number of supply ports is not particularly limited, and the number of supply ports may be appropriately determined according to the number of target layers.

A third mode for producing the ceramic fine particles having a multi-layer structure is an apparatus combining the first mode and the second mode. That is, the coaxial double cylinder type reactor is provided with a nuclear fine particle supply port, a nuclear fine particle supply means is connected, and two or more source gas supply ports are provided (FIG. 4). By using this device,
It is possible to generate ceramic fine particles having a multi-layered structure composed of a plurality of ceramic adhered layers on the surface of the nuclear fine particles. As each device and each member in this mode, the same devices as those in the first mode and the second mode can be used.

Next, a method for producing the ceramic fine particles of the present invention using the apparatus of the present invention as described above will be described. The raw material gas used in the present invention is obtained by vaporizing one or more kinds of metal compounds. As shown in FIG. 3, when two or more source gas supply ports are provided, different types of source gas are used. The metal element used as the metal compound is specifically an alkali metal, an alkaline earth metal, a transition metal or the like. For example,
Alkali metals include Li, Na, K, Rb, Cs, Fr,
Alkaline earth metals are Be, Mg, Ca, Sr, Ba, R
a, transition metals are Sc, Ti, V, C of the 4th period of the periodic table
r, Mn, Fe, Co, Ni, Cu, Zn, Ga, G
e, As, Y, Zr, Nb, Mo, Tc, R in the fifth cycle
u, Rh, Pd, Ag, Cd, In, Sn, Sb, 6th
Period La, Hf, Ta, W, Re, Os, Ir, P
In addition to t, Au, Hg, Tl, Pb, Bi, etc., Al,
Si etc. are mentioned.

The type of metal compound is an organic metal compound such as a metal chloride, a metal hydride, a metal alkoxide, a metal alkylate or a metal β-diketone. Specific examples of the metal compound include TiCl ₄ and SiCl
₄ , SiH ₄ , AsH ₃ , Ti (OC ₃ H ₇ ) ₄ , Al
(OC ₃ H ₇ ) ₃ , Al (CH ₃ ) ₃ , Zn (C
₂ H ₅ ) ₂ , Zn (C ₁₁ H ₁₉ O ₂ ) ₂ , Zr (C ₁₁ H ₁₉
O ₂ ) _{4 and the} like.

These metal compounds are used alone or as a mixture in the gas phase. As a mixture, for example, T
When a mixed gas of i (OC ₃ H ₇ ) ₄ gas and Zn (C ₂ H ₅ ) ₂ gas is used, composite fine particles of TiO ₂ fine particles and ZnO fine particles are obtained by the CVD method.

The carrier gas is an inert gas or a gas that does not hinder the progress of a chemical reaction. For example, helium, air, nitrogen or the like is used, and the flow rate of the carrier gas is Taylor vortex which is an annular gas phase vortex. It is preferable to adjust the flow rate of the carrier gas so that the flow rate is not so high as to break and the residence time of the carrier gas containing the raw material gas in the reaction space does not become shorter than 1 second.

The source gas concentration is preferably in the range of 0.001 to 40% by weight, relative to the carrier gas, and 0.01 to 40% by weight.
A range of 20% by weight is desirable. The reason is that when the raw material gas concentration is less than 0.001% by weight, the amount of fine particles produced is extremely small, and when the raw material gas concentration is greater than 40% by weight, the raw material gas molecules are agglomerated with each other and the inner fine particle cylinder is formed. And the adhesion to the outer cylindrical wall surface occurs violently, the sizes of the produced fine particles become non-uniform, and the yield thereof deteriorates.

In the method of the present invention, by introducing the nuclear fine particles into the reaction space, the fine particles having a multi-layered structure can be produced by coating the fine particles with the ceramic produced by the reaction of the raw material gas. The nuclear fine particles are inorganic substances such as metals and ceramics, organic substances, or composites thereof, which have a size such that they can be moved by the carrier gas without being deposited in the reaction space, and for example, TiO ₂ Examples thereof include fine particles, mica fine particles, iron powder, and polymer beads.

The carrier gas for transporting the nuclear fine particles is the same as the carrier gas for transporting the raw material gas,
An inert gas or a gas that does not hinder the progress of the chemical reaction of the raw material gas in the reaction space, and for example, helium, air, nitrogen or the like is used. Further, the flow rate combined with the carrier gas for transporting the raw material gas is equal to or lower than the flow rate that does not break the Taylor vortex which is the annular gas phase vortex, and the carrier gas containing the raw material gas and the nuclear fine particles in the reaction space. It is preferable to adjust the flow rate of the carrier gas so that the residence time is not shorter than 1 second.

The nuclear fine particles can be supplied to the reaction space from a supply port 12 provided at the inlet (top) of the reaction space as shown in FIG. The nuclear fine particle supply port 12 is usually provided around the inlet of the reaction space as described above, but it may be any mode as long as the ceramics resulting from the reaction of the raw material gas can be attached to the surface of the nuclear fine particle. The position can be appropriately selected in relation to the position where the supply port is provided, and may be provided on the outer cylindrical wall portion near the inlet.

Incidentally, in some applications where not only the characteristics of the ceramics to be deposited but also the characteristics of the nuclear fine particles need to be elicited strongly, it may be preferable that the deposition on the surface of the nuclear fine particles is rather partial. In order to obtain ceramic fine particles having such a multi-layered structure, a supply port for core fine particles may be provided at a subsequent stage position in the axial direction of the inner cylinder. That is, for example, it is provided on the wall surface around the center of the outer cylinder, but the length from the entrance of the reaction space is appropriately selected depending on the intended ceramic fine particles.

The introduction of the nuclear fine particles into the reaction space is carried out in a carrier gas by using a powder supplying / dispersing device or the like so that the surface of the nuclear fine particles is sufficiently brought into contact with the gas phase and the coating is uniformly performed. It is preferable to introduce it in the reaction space in a dispersed state. The dispersion concentration is preferably 10 ² to 10 ²⁰ particles / m ³ . When the concentration is higher than 10 ²⁰ particles / m ^3, the dispersibility of the core fine particles is poor, and when the concentration is lower than 10 ² particles / m ³ , the productivity of the coated particles produced is significantly reduced. Ceramics produced as a result of the reaction of the raw material gas are deposited on the surface of the nuclear fine particles in the form of atomic species, molecular species, or active species or aggregates thereof, and are accumulated to form a coating layer. The structure of the coating layer is generally a uniform layer, although it varies depending on the state of deposition and the state of the reaction space. It may become like this.

The raw material gas may be introduced from a single supply port 9 as shown in FIG. 1, or as shown in FIG. 3, the supply ports 9a and 9b may be provided at two or more places to carry out a stepwise reaction. It can also be supplied into the space. In the latter case, after the ceramics that will become the nucleus are generated by the reaction of the gas supplied from the supply port provided at the inlet of the reaction space, another type of source gas is supplied from the supply port provided at the subsequent stage in the axial direction of the inner cylinder. Can be supplied in a single stage or in multiple stages to sequentially coat core particles with ceramics produced by each reaction in the reaction space to obtain fine particles having a multilayer structure.

When two or more source gas supply ports are provided, the position of the source gas supplied in the preceding stage is set so as to reduce the mixture of substances between the coating layers constituting the multi-layer structure fine particles. It is preferable that the position is such that the reaction is mostly advanced. The reaction rate is preferably 80% or more, more preferably 90% or more.

The fine particles produced in the process of producing the fine particles having a multi-layer structure, are moved to a later stage in the reaction space,
The surface is coated with a substance in the form of an atom, a molecule, or an active species or an aggregate thereof, which results from the reaction of the source gas, and a coating layer is sequentially formed. The structure of each coating layer is usually a uniform layer, although it depends on the state of the deposition and the state of the reaction space.Depending on the position of the raw material gas supply port provided in the subsequent stage, the deposition is partially uniform. It may become like an aggregate of fine particles.

In the coaxial double-cylindrical reactor described above, the flow velocity in the vicinity of the rotating inner cylinder is higher than that in the vicinity of the outer cylinder, and therefore the centrifugal force of the fluid mass rotating in the vicinity of the inner cylinder is Becomes larger than the centrifugal force of the fluid mass rotating near the outer cylinder, and the fluid mass near the inner cylinder becomes a discharge flow toward the outer cylinder and jets out.Instead, the fluid mass near the outer cylinder becomes a return flow. Flow toward the inner cylinder. A Taylor vortex flow is formed in the reaction space by the discharge flow and the return flow. These vortices are independent of each other, and there is almost no mixing between them. Therefore, the raw material gas introduced from the inlet of the reaction space enters the Taylor vortex flow, the temperature and the raw material gas concentration in the vortex flow are uniform, and if the introduction speed is constant, the raw material gas in each vortex flow is in the reaction space. Dwell time is constant.

In the coaxial double-cylindrical reactor, conditions for forming a Taylor vortex flow in the reaction space when an axial flow is given are as follows: inner cylinder diameter, annular portion width between inner and outer cylinders, gas phase The viscosity, the rotational angular velocity of the inner cylinder, and the axial velocity of the gas phase are included. The formation of the Taylor vortex flow is determined by a combination of these conditions.The conditions for generating the Taylor vortex flow and the conditions for allowing the Taylor vortex flow to pass through the reaction space of the coaxial double cylindrical reactor without destroying the Taylor vortex flow are as follows. It is defined by the Taylor number and Reynolds number represented by the formula. Ta = (Ri..omega..d / .nu.) (D / Ri) ^1/2 Re = d.u / .nu. (Where Ta is the Taylor number, Ri is the inner cylinder diameter, and .omega. Is the rotational angular velocity of the inner cylinder, Re. Is the Reynolds number, d is the width of the annular portion between the inner and outer cylinders, ν is the kinematic viscosity of the gas phase, and u is the axial velocity of the gas phase.)

In the present invention, the condition for the Taylor vortex flow is that the Taylor number is preferably in the range of 40 to 15,000, more preferably 70 to 10,000.
The range of up to 5000 is particularly preferable. The reason is that if the Taylor number is less than 40, Taylor vortex flow does not occur, and if the Taylor number is more than 15000, the vortex structure disappears.

As a condition for allowing the Taylor vortex flow generated under the above conditions to pass through the reaction space of the coaxial double cylindrical reactor, a Reynolds number of more than 0.05 and less than 2000 is preferable. The range of 0.5 to 500 is desirable. The reason is that when the Reynolds number is less than 0.05, the carrier gas flow rate becomes small, and the production efficiency is lowered. Further, if the Reynolds number is larger than 2000, the Taylor vortex flow is pushed by the axial flow and is broken.

Within the ranges of the above Taylor number and Reynolds number, the conditions for generating the Taylor vortex flow and the conditions for allowing the Taylor vortex flow to pass through the reaction space of the coaxial double cylindrical reactor without breaking the Taylor vortex flow are satisfied. That is, it can be said that the condition for forming the Taylor vortex flow in the reaction space is satisfied. Further, the pressure in the reaction space is not limited, but it is desirable that the pressure is normal pressure or increased pressure in order to increase the density of the raw material gas and improve the stability of the vortex flow.

The ceramic fine particles obtained by the present invention have good monodispersity, the fine particle surface is clean, and the range of 0.001 to 10 μm can be obtained by adjusting the concentration of the raw material gas or the residence time of the gas in the reaction space. However, the range of 0.001 to 1 [mu] m is preferable in consideration of the improvement of the function by making the particles fine. The diameter of the ceramic fine particles can be measured by various methods, for example, a scanning electron microscope or a transmission electron microscope.

When fine particles having a multilayer structure are produced, in addition to the above characteristics, uniform particles of the coating layer can be obtained. The thickness of each coating layer is the particle diameter d of the portion inside the coating layer.
The ratio dp / Dp of the particle diameter Dp of the portion including p and the coating layer is preferably in the range of 0.5 to 0.9999. When dp / Dp is less than 0.5, it cannot be expected that the property of the portion inside the coating layer will extend to the outside through the coating layer, and when dp / Dp exceeds 0.9999, the coating is performed. The formation of the layer is insufficient and the properties of the coating layer cannot be expected to be exhibited.

In this way, the raw material gas obtained by vaporizing one kind or a plurality of kinds of metal compounds is supplied to the reaction space of the coaxial double cylindrical reactor by the carrier gas, and the raw material gas is formed under the condition of Taylor vortex flow. By reacting the gas, uniform ceramic fine particles can be easily produced. Further, according to the method of the present invention, it is possible to effectively prevent the produced fine particles from adhering to the inner and outer cylindrical wall surfaces by the scraping effect by the Taylor vortex flow, so that it is possible to produce ceramic fine particles in a high yield.

[0045]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Example 1 Ceramic fine particles were produced using the reactor shown in FIG. That is, titanium tetraisopropoxide (Ti (OC ₃ H ₇ ) ₄ ) was evaporated by an evaporator at 50 ° C., and a nitrogen carrier gas whose flow rate was controlled to 10 L / min (the kinematic viscosity of nitrogen gas at 600 ° C. was 0 .98
cm ² / s) with a heating furnace outside the outer cylinder
Coaxial double-cylindrical reactor controlled at a temperature of 00 ° C (stainless steel, inner cylinder diameter 100 mm, outer cylinder diameter 133 mm,
(Width of the annular portion between the inner and outer cylinders is 16.5 mm, length is 57 cm)
From the bottom to the reaction space that exists in the gap between the inner and outer cylinders,
The peripheral velocity of the outer surface of the inner cylinder was controlled to 262 cm / s (rotation speed of the inner cylinder was 500 rpm) to maintain the Taylor vortex flow forming conditions. Raw material gas to generate TiO ₂ fine particles are thermally decomposed during passage through the reaction space, and recovered by diffusion charging-type electrostatic collector of the TiO ₂ fine particles contained in the gas phase was mounted just after the reaction space outlet. At this time, the source gas concentration was 0.16% by weight with respect to the nitrogen carrier gas, and the average residence time of the gas in the reaction space was about 21 by measuring the evaporation amount of the source material using a gravimetric method. Seconds. Further, the Taylor number is 358 and the Reynolds number is 4.6, which satisfies the condition for forming the Taylor vortex flow described above.

The TiO ₂ fine particles obtained under the above conditions have an amorphous crystal phase and a partial mixture of anatase, and the TiO ₂ particle diameter is about 0.03 μm in average diameter (number basis). The particle size distribution is 0.01 to
15% for 0.02 μm, 70 for 0.02-0.04 μm
%, 0.04 to 0.06 μm is 10%, 0.06 to 0.
10 μm was 5%. In addition, the yield (weight ratio) of the TiO ₂ fine particles collected by the filter was 98%. The crystal phase of the produced TiO ₂ fine particles was measured by an X-ray diffractometer, and the fine particle diameter was measured by using a scanning electron microscope. Hereinafter, also in Comparative Example 1, the measurement was performed by the same method.

Comparative Example 1 Using the same reactor and conditions as in Example 1, the inner cylinder was not rotated, that is, Taylor vortex flow was not generated,
A fine particle generation experiment was performed by thermal decomposition of the raw material gas in the extrusion flow. The crystal phase of the TiO ₂ fine particles obtained under the above conditions is amorphous and a part of anatase is mixed, and the TiO ₂ particle diameter is an average diameter (on a number basis).
Is about 0.04 μm, and the particle size distribution is 0.01
~ 0.02μm is 20%, 0.02-0.04μm is 4
0%, 0.04 to 0.06 μm is 30%, 0.06 to
0.10 μm was 10%, and it can be said that the particle size distribution is wider and the monodispersity is inferior as compared with the case of Example 1 in which fine particles are generated under the condition of Taylor vortex flow. Also,
TiO ₂ microparticles yield trapped in filter (weight ratio) is 83% for TiO ₂ fine particles are adhered to the inner cylinder and the outer cylinder wall, subjected to microparticle generation under the conditions of formation of the Taylor vortex flow It can be said that the yield is poor as compared with the case of Example 1.

Example 2 Using the reactor shown in FIG. 2, ceramic fine particles having a multilayer structure were produced. The type and vaporization temperature of the raw material gas, the temperature of the reaction space, the size, the shape, and the rotation speed of the inner cylinder are the same as in Example 1. A raw material gas was introduced from a supply port 9 provided at the top of the reaction space by using a nitrogen carrier gas whose flow rate was controlled to 5 L / min, and similarly, mica fine particles (plate-like, average A state in which a diameter of about 5 μm and an average thickness of about 0.25 μm are dispersed in nitrogen gas using a powder supply and dispersion device (about 5 × 10 ¹⁰⁾
/ M ³ ) was supplied into the reaction space. At this time, the flow rate of nitrogen gas containing mica fine particles was controlled to 1 L / min. The surface of the mica fine particles was coated with TiO ₂ produced by thermal decomposition of the raw material gas while passing through the reaction space. The TiO ₂ -coated mica fine particles contained in the gas flowing out from the bottom of the reaction space were recovered by the same method as in Example 1.

At this time, the raw material gas concentration was 0.17% by weight with respect to the nitrogen carrier gas, and the average residence time of the gas in the reaction space was about 36 seconds. The Taylor number is 358 and the Reynolds number is 2.8, which satisfies the above-mentioned Taylor vortex flow forming conditions. The TiO ₂ -coated mica fine particles obtained under the above conditions were analyzed by X-ray diffraction, and it was found that the crystal phase of the TiO ₂ coating layer was amorphous and some anatase was mixed. Further, as a result of observing the cross section of the fine particles with a transmission electron microscope, the coating layer has a uniform layered structure and its average thickness is about 0.11 μm.
The ratio dp / Dp of the particle diameter dp of the mica fine particles and the particle diameter Dp of the TiO ₂ coated mica fine particles is 0.98. As for the distribution of the coating layer thickness, 0.08 μm or less is 2%, 0.08 to 0.1.
μm is 10%, 0.1-0.12 μm is 72%, 0.1
2 to 0.14 μm was 13%, and 0.14 μm or more was 3%. Regarding the appearance of the fine particles, the entire color was flesh-colored and had a vivid pearly luster, and the coloring characteristics were uniform throughout. In addition, the TiO collected by the filter
The yield (weight ratio) of the _2- coated mica fine particles was 97%.

Comparative Example 2 Using the same reactor and conditions as in Example 2, the inner cylinder was not rotated, that is, Taylor vortex flow was not generated,
A fine particle generation experiment was carried out by thermal decomposition of the raw material gas in the extrusion flow. In the TiO ₂ coated mica fine particles obtained under the above conditions, the crystal phase of the TiO ₂ coated layer was amorphous and some anatase was mixed. The average thickness of the coating layer is about 0.09 μm, and the distribution of the coating layer thickness is 0.06 μm.
The following is 10%, 0.06 to 0.08 μm is 23%, and 0.
08-0.1 μm is 45%, 0.1-0.12 μm is 1
4%, 0.12 μm or more was 8%. It can be said that the coating layer thickness distribution is wider and the monodispersity is inferior as compared with the case of Example 2 in which the fine particles are generated under the condition of Taylor vortex flow formation. Further, the yield (weight ratio) of the TiO ₂ -coated mica fine particles collected by the filter was 87% because the produced fine particles adhered to the inner and outer cylindrical wall surfaces, and the fine particles were formed under the Taylor vortex formation conditions. It can be said that the yield is poor as compared with the case of Example 2 in which the production is performed.

Example 3 Using the reactor shown in FIG. 3, ceramic fine particles having a multilayer structure were produced. The temperature, size, shape, and rotation speed of the inner cylinder of the reaction space are all the same as in Example 1. Aluminum isopropoxide (Al (OC ₃
H ₇ ) ₃ ) is evaporated at 100 ° C. by the evaporator 5a,
Using a nitrogen carrier gas whose flow rate was controlled to 1 L / min, the nitrogen carrier gas was supplied from a supply port 9a provided at the bottom of the reaction space. Further, titanium tetraisopropoxide was added to the evaporator 5b.
At a temperature of 1 L / min by using a nitrogen carrier gas whose flow rate is controlled to 1 L / min, through a supply port 9b (the distance from the top of the reaction space to the supply port 9b is 10 cm) provided in the outer cylindrical wall. Introduced into the space. Al ₂ O produced by thermal decomposition reaction of aluminum isopropoxide
The surfaces of the _three fine particles were coated with TiO ₂ generated by the thermal decomposition reaction of titanium tetraisopropoxide, and TiO ₂ -coated Al ₂ O ₃ fine particles were produced. The coated fine particles contained in the gas flowing out from the top of the reaction space were recovered by the same method as in Example 1.

At this time, the raw material gas concentration was aluminum isopropoxide 0.3 with respect to the nitrogen carrier gas.
5 wt%, titanium tetraisopropoxide 0.17 wt%, and the average residence time of the raw material gas in the reaction space is about 188 seconds for aluminum isopropoxide and about 18 seconds for titanium tetraisopropoxide. The Taylor number is 358, the Reynolds number is 0.46 from the bottom of the reaction space to the supply port 9b, and 0.93 at the part after the supply port 9b.
And satisfies the condition for forming the Taylor vortex flow described above.

TiO ₂ coated Al obtained under the above conditions
_{The 2} O ₃ fine particles were analyzed by X-ray diffraction and found to be Al ₂ O.
₃ crystalline phases γ type close to amorphous core particles, TiO ₂
It was found that the crystal phase of the coating layer was amorphous and some anatase was mixed. As a result of observation with a scanning electron microscope, the average particle size (number basis) was about 0.7 μm, and the particle size distribution was 0.5 μm or less, 2%, 0.5-
0.6 μm is 9%, 0.6 to 0.7 μm is 45%, and 0.
28% for 7 to 0.8 μm, 12 for 0.8 to 0.9 μm
%, And 0.9 μm or more was 4%. As a result of observing the particle cross section with a transmission electron microscope, both the Al ₂ O ₃ core particle portion and the TiO ₂ coating layer had a uniform layered structure, and a clear boundary was observed between them. The average thickness of the coating layer is about 0.05 μm, and the particle diameter dp and T of Al ₂ O ₃ core particles are
Ratio of particle size Dp of Al ₂ O ₃ fine particles coated with iO ₂ dp / D
p is 0.93, and the coating layer thickness distribution is 0.03μ.
m or less is 1%, 0.03 to 0.04 μm is 7%, 0.0
4-0.05 μm 46%, 0.05-0.06 μm 41%, 0.06-0.07 μm 5%, 0.07 μm
The above was 0%. Also, the T collected by the filter
The yield (weight ratio) of the iO ₂ -coated Al ₂ O ₃ fine particles is 96%.
Met.

Comparative Example 3 Using the same reactor and conditions as in Example 3, the inner cylinder was not rotated, ie, Taylor vortex flow was not generated,
A fine particle generation experiment was carried out by thermal decomposition of the raw material gas in the extrusion flow. In the TiO ₂ -coated Al ₂ O ₃ fine particles obtained under the above conditions, the crystal phase of the Al ₂ O ₃ core particles is γ-type, which is close to amorphous, and the crystal phase of the TiO ₂ coating layer is amorphous and some anatase is mixed. I understood it. The average particle size (number basis) is about 0.7 μm, and the particle size distribution is 0.5% or less, 4%, 0.5 to 0.
6 μm is 15%, 0.6-0.7 μm is 33%, 0.7
~ 0.8 μm is 26%, 0.8-0.9 μm is 18%,
4% was 0.9 μm or more. The average thickness of the coating layer is about 0.05 μm, and the distribution of the coating layer thickness is 0.03 μm or less 13%, 0.03 to 0.04 μm 15%, 0.0
28% of 4 to 0.05 μm, 23% of 0.05 to 0.06 μm, 14% of 0.06 to 0.07 μm, 0.07 μm
m or more was 7%. Compared with the case of Example 3 in which fine particles are generated under the condition of Taylor vortex flow, the distribution of the coating particle diameter and the coating layer thickness is wider, and the monodispersity of the particle diameter and the uniformity of the coating layer are inferior. I can say. Further, the yield (weight ratio) of the TiO ₂ -coated Al ₂ O ₃ fine particles collected by the filter was 79% because the produced fine particles adhered to the inner and outer cylindrical wall surfaces. It can be said that the yield is poor as compared with the case of Example 3 in which fine particles are generated below.

Example 4 Using the reactor shown in FIG. 4, multi-layer structure ceramic fine particles were produced. The temperature, size, shape, and rotation speed of the inner cylinder of the reaction space are all the same as in Example 1. Titanium tetraisopropoxide was heated to 50 ° C by the evaporator 5a.
And a supply port 9 provided at the top of the reaction space using a nitrogen carrier gas whose flow rate is controlled to 1 L / min.
A state in which Fe ₂ O ₃ fine particles (average diameter of about 0.9 μm) introduced from a through a supply port 12 provided at the top were dispersed in nitrogen gas using a powder supply and dispersion device (about 10 ¹²
/ M ³ ) was supplied into the reaction space. At this time Fe ₂ O ₃
The flow rate of nitrogen gas containing fine particles was controlled to 1 L / min. Further, aluminum isopropoxide is added to the evaporator 5b.
By using a nitrogen carrier gas whose flow rate is controlled to 1 L / min by using a nitrogen carrier gas controlled at a flow rate of 1 L / min through a supply port 9b (the distance from the top of the reaction space to the supply port 9b is 10 cm). Introduced into the space. Fe ₂ O
₃ The surfaces of the fine particles are coated with TiO ₂ produced by the thermal decomposition reaction of titanium tetraisopropoxide, and Al produced by the thermal decomposition reaction of aluminum isopropoxide.
The outside is coated with _{2 O 3, Fe 2 O 3} / TiO 2
/ Al ₂ O ₃ multi-layered fine particles were produced. The multi-layered structure fine particles contained in the gas flowing out from the bottom of the reaction space were recovered by the same method as in Example 1.

At this time, the source gas concentration was titanium tetraisopropoxide 0.17 with respect to the nitrogen carrier gas.
% By weight, 0.35% by weight of aluminum isopropoxide, and the average residence time of the raw material gas in the reaction space is about 75 seconds for titanium tetraisopropoxide and about 57 seconds for aluminum isopropoxide. The number of Taylor is 3
58, the Reynolds number was 0.93 in the portion from the top of the reaction space to the supply port 9b, and 1.4 in the part after the supply port 9b, which satisfied the condition for forming the Taylor vortex flow described above.

Fe ₂ O ₃ / Ti obtained under the above conditions
As a result of analysis by X-ray diffraction, the O ₂ / Al ₂ O ₃ multi-layer structure fine particles showed that the crystal phase of the TiO ₂ coating layer was amorphous and some anatase was mixed, and the crystal phase of the Al ₂ O ₃ coating layer was It was found to be γ type, which is close to amorphous. As a result of observing the particle cross section with a transmission electron microscope, TiO ₂
Both the coating layer and the Al ₂ O ₃ coating layer had a uniform layered structure, and a clear boundary was observed between them. TiO ₂
The average thickness of the coating layer is about 0.05 μm, and the ratio dp / Dp of the particle diameter dp of the Fe ₂ O ₃ core fine particles and the particle diameter Dp of the portion including the TiO ₂ coating layer is 0.89. The distribution of the TiO ₂ coating layer thickness is 0.03 μm or less, 0%, 0.03
~ 0.04μm is 3%, 0.04 ~ 0.05μm is 21
%, 0.05 to 0.06 μm is 69%, 0.06 to 0.
07 μm was 7%, and 0.07 μm or more was 0%. The average thickness of the outermost Al ₂ O ₃ coating layer is about 0.07μ.
m, the ratio dp / Dp of the particle diameter dp of the portion excluding the Al ₂ O ₃ coating layer and the particle diameter Dp of the entire multilayer structure fine particles is 0.8.
It becomes 7. Al ₂ O ₃ coating layer thickness distribution is 0.04μ
m or less is 1%, 0.04 to 0.06 μm is 20%, and 0.
The value of 06-0.08 μm was 76%, the value of 0.08-0.1 μm was 3%, and the value of 0.1 μm or more was 0%. Further, the yield (weight ratio) of the Fe ₂ O ₃ / TiO ₂ / Al ₂ O ₃ multi-layered structure fine particles collected by the filter was 98%.

Comparative Example 4 Using the same reactor and conditions as in Example 4, without rotating the inner cylinder, that is, without generating Taylor vortex flow,
A fine particle generation experiment was conducted by thermal decomposition of the raw material gas in the extrusion flow. Fe ₂ O ₃ / T obtained under the above conditions
In the iO ₂ / Al ₂ O ₃ multi-layer structure fine particles, the crystal phase of the TiO ₂ coating layer is amorphous and some anatase is mixed, and the crystal phase of the Al ₂ O ₃ coating layer is close to amorphous γ
It was a mold. The average thickness of the TiO ₂ coating layer is about 0.05μ
m, the TiO ₂ coating layer thickness distribution is 0.03 μm or less 6%, 0.03 to 0.04 μm 13%, 0.04 to 0.04 μm.
0.05 μm is 24%, 0.05 to 0.06 μm is 37
%, 0.06 to 0.07 μm was 15%, and 0.07 μm or more was 5%. The average thickness of the Al ₂ O ₃ coating layer which is the outermost layer is about 0.07 μm, and the distribution of the Al ₂ O ₃ coating layer thickness is 0.04 μm or less 6%, 0.04 to 0.06 μm.
m is 35%, 0.06-0.08 μm is 44%, 0.0
8 to 0.1 μm was 13%, and 0.1 μm or more was 2%. Compared with the case of Example 4 in which fine particles are generated under the condition of Taylor vortex flow, the coating layer thickness distribution is Ti
It can be said that both O ₂ and Al ₂ O ₃ are wide and the uniformity of the coating layer is poor. In addition, Fe ₂ O ₃ / Ti collected by the filter
The yield (weight ratio) of O ₂ / Al ₂ O ₃ multi-layered structure fine particles is
The generated fine particles adhered to the inner and outer cylindrical wall surfaces, resulting in 78%, which means that the yield is worse than in the case of Example 4 in which the fine particles are generated under the condition of Taylor vortex flow.

[0059]

According to the present invention, since the Taylor vortex flow is adopted as the flow of the CVD reaction field, the temperature distribution in the vortex flow, the reaction gas concentration distribution, and the residence time of the produced fine particles trapped in the vortex flow. Becomes uniform, and it becomes possible to obtain uniform fine particles with high yield. Further, by supplying the nuclear fine particles to the reaction space and supplying the raw material gas to the reaction space from two or more supply ports, it is possible to obtain the multi-layer structure fine particles in which the thickness of each layer is uniform in a high yield. Therefore, a wide variety of ceramic fine particles can be continuously produced with high yield and low cost by the simple process of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a fine particle production apparatus according to the present invention.

FIG. 2 is a schematic view showing an example of a multi-layer structure fine particle production apparatus according to the present invention.

FIG. 3 is a schematic view showing an example of an apparatus for producing multi-layer structure fine particles according to the present invention.

FIG. 4 is a schematic view showing an example of a multi-layer structure fine particle production apparatus of the present invention.

[Explanation of symbols]

 1 Inner Cylinder 2 Outer Cylinder 3 Inner Cylinder Rotation Drive Device 4 Energy Supply Device Required for Chemical Reaction 5 Raw Material Vaporizer 5a Raw Material Vaporizer (Evaporator) 5b Raw Material Vaporizer (Evaporator) 6 Carrier Gas Supply Device 6a Carrier Gas Supply device 6b Carrier gas supply device 7 Particulate collection device 8 Reaction space 9 Source gas supply port 9a Source gas supply port 9b Source gas supply port 10 Powder supply / dispersion device 11 Powder transport carrier gas supply device 12 Nuclear Fine particle supply port

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sachiko Kokubo 2090-705 Hiranuma, Yoshikawa-cho, Kitakatsushika-gun, Saitama Prefecture (72) Inventor Keiichi 4-1-1 Sekido, Wakayama City, Wakayama Prefecture

Claims (7)

[Claims] 1. A coaxial double-cylindrical reactor having a stationary outer cylinder and a rotatable inner cylinder, wherein a raw material gas is obtained by vaporizing one or a plurality of kinds of metal compounds. Is supplied to a reaction space provided in an annular portion between the inner and outer cylinders, and the raw material gas is reacted in the reaction space while rotating the inner cylinder. 2. In addition to the raw material gas, core fine particles are further supplied to the reaction space by a carrier gas, and the surface of the core fine particles is coated with ceramics produced by the reaction of the raw material gas. Production method. 3. Ceramics produced by the reaction of each raw material gas by feeding different raw material gases into the reaction space through carrier gas from two or more supply ports provided in the coaxial double cylindrical reactor. 3. The method according to claim 1, wherein fine ceramic particles having a multi-layer structure are formed. 4. The method according to claim 1, wherein the number of revolutions of the inner cylinder is controlled so that the gas in the reaction space forms a Taylor vortex flow. 5. The Taylor number and the Reynolds number represented by the following equations are 40 to 15,000 and 0.05, respectively.
The manufacturing method according to any one of claims 1 to 4, wherein the rotational angular velocity of the inner cylinder and the axial velocity of the gas phase are controlled so as to fall within a range of to 2,000. Ta = (Ri..omega..d / .nu.) (D / Ri) ^1/2 Re = d.u / .nu. (Where Ta is the Taylor number, Ri is the inner cylinder diameter, and .omega. Is the rotational angular velocity of the inner cylinder, Re. Is the Reynolds number, d is the width of the annular portion between the inner and outer cylinders, ν is the kinematic viscosity of the gas phase, and u is the axial velocity of the gas phase.) 6. A raw material vaporizer for vaporizing one or a plurality of types of metal compounds to generate a raw material gas, a carrier gas supply device for transporting the raw material gas, and a stationary external device for forming a Taylor vortex flow. A coaxial double-cylindrical reactor having a cylinder and a rotatable inner cylinder and a feed gas supply port, an inner cylinder rotation driving device for rotating the inner cylinder, and energy required for chemical reaction inside and outside An energy supply device for supplying into a reaction space provided in an annular portion between cylinders, and a fine particle collection device for collecting fine particles in a gas phase exiting from the reaction space. Manufacturing equipment. 7. The production apparatus according to claim 6, wherein the coaxial double-cylindrical reactor is further provided with a nuclear fine particle supply port and is connected to a nuclear fine particle supply means.