JPH06142496A - Production and apparatus for production of particle of which surface is coated with superfine particle - Google Patents

Abstract

PURPOSE:To improve the strength of adhesion of particles, to keep a base material free from thermal damage, and to make the coverage and grain sizes of superfine particles controllable by changing the position where the material particles of a base material to be coated are introduced into the flow of the superfine particles of the formed material according to purposes. CONSTITUTION:The superfine particle raw materials introduced from a superfine particle raw material supplying device D are released together with carrier gas flow to the lower part of a plasma torch A and evaporates by coming into contact with plasma flames. On the other hand, the base raw material particles supplied from a base raw material supplying device E are carried in the carrier gas flow and are released through a base material supplying nozzle G into a reaction zone B. This base material supplying nozzle G has a temp. detector at its front end so that the position of the nozzle G can be adjusted while the temp. of the base material supplying position is decided. The temp. distribution within the reaction zone reacts depends largely on plasma generating conditions, etc. The base material particles are supplied to the temp. region suitable for coating and efficient coating is possible according to this method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing particles in which base particles of an inorganic material or a metal material are coated with ultrafine particles of the inorganic material or the metal material.

[0002]

2. Description of the Related Art In the production of a sintered compact by sintering a powder of an inorganic material or a metal material, the above-mentioned purpose has been used for the purpose of lowering the sintering temperature and improving the physical properties of the compact. It is often practiced in this technical field to add a sintering aid to a powder and sinter it.

Various kinds of sintering aids have been used so far, but the present inventors have prepared powders by adding ultrafine particles of the aid to the powder of an inorganic material. A patent application was filed (see Japanese Patent Application No. 63-68037), finding that the reactivity with an auxiliary agent can be improved, the sintering characteristics can be improved, and the physical properties of the obtained sintered compact can be extremely improved.

The method of application by the present inventors is to produce a sintered compact by adding a separately produced ultrafine particle auxiliary agent to the inorganic powder to be sintered. It is used by mixing two components. Therefore, this method requires homogeneous mixing of the two components, but since the ultrafine particle auxiliary agent has a strong tendency to aggregate, extremely careful handling is required when mixing the two components while maintaining a highly dispersed state. Besides, it is necessary to separately prepare two separately prepared components.

Therefore, if the auxiliaries can be combined and integrated into the powder to be sintered in the form of ultrafine particles, not only the difficulties in mixing the two components mentioned above can be avoided, but also the powder material With the idea that it is possible to simplify handling, thus making it extremely easy to produce a sintered body, and obtaining a homogeneous and high-quality sintered body, as a result of research, it was found that The inventors have completed inventions of particles of an inorganic material or a metal material, the surfaces of which are coated with ultrafine particles, and a method for producing the particles, and filed a patent application (see Japanese Patent Application No. 1-75016 and Japanese Patent Application Laid-Open No. 3-75302).

The particles of the inorganic material or the metal material, the surface of which is coated with the ultrafine particles of the inorganic material or the metal material, are coated in the flow containing the ultrafine particles of the inorganic material or the metal material produced by the vapor phase method. It is obtained by introducing particles of an inorganic material or a metal material to be treated, and bringing the above ultrafine particles and the above-mentioned particles to be coated into contact with each other in a fluid state.

[0007]

By the way, when the base material particles of the inorganic material or the metal material are coated with the ultrafine particles of the inorganic material or the metal material, the base material particles are one of the means for improving the adhesion strength of both particles. Is supplied to a higher temperature region to achieve the purpose of improving the bond strength.

On the contrary to the above, when the base material of the inorganic material or the metal material is a material that is easily damaged by heat when the inorganic material or the metal material is coated with the ultrafine particles, for example, when the base material is the diamond particles. For example, it is necessary to supply the base material in a temperature range where the base material is not damaged by heat.

Furthermore, the amount of the ultrafine particles coated on the base material of the inorganic material or the metal material is correlated with the contact time of both particles, and thus the particle size of the coated particles produced also depends on the contact time. Therefore, in order to control the coating amount of ultrafine particles and the particle size, it is necessary to adjust the residence time of the base material particles in the reaction zone.

[0010]

In order to solve the above problems, as a result of intensive research by the present inventor, the base material to be coated with the ultrafine particles in the flow of the ultrafine particles of the produced inorganic material or metal material. The present invention has been completed by finding that the above-mentioned problems can be achieved by making it possible to change the introduction position of the inorganic material or metal material particles according to the purpose.

That is, according to the present invention, a flow of ultrafine particles of an inorganic material or a metal material is generated by a gas phase method, and the surface of the inorganic material or the metal material to be coated with the ultrafine particles is generated in the flow of the ultrafine particles. In the method of introducing the base material particles and bringing the ultrafine particles and the particles of the base material into contact with each other in a fluid state to coat the surface of the base material particles with the ultrafine particles, the introduction position of the base material particles can be changed. Regarding the above method.

Still further, the present invention provides an apparatus for producing a flow of ultrafine particles of an inorganic material or a metallic material by a vapor phase method,
Introducing into the flow of ultrafine particles base particles of an inorganic or metallic material whose surface is to be coated with the ultrafine particles, so that the ultrafine particles and the base material particles can be brought into contact with each other in a fluidized state. The charging device for the base material particles is configured to change the introduction position of the base material particles,
The present invention also relates to an apparatus for producing particles in which the surface of base material particles of an inorganic material or a metal material is coated with ultrafine particles of an inorganic material or a metal material.

The above-mentioned change of the introduction position of the base material particles can be achieved by various technical means, and one of them is, in the apparatus for carrying out the present invention, the inorganic material or the inorganic material supplied in the plasma flame. A zone in which a flow of ultrafine particles of an inorganic material or a metal material produced by evaporation of a metal material due to high temperature of plasma flame and an inorganic or metal material coating the surface with the ultrafine particles (the reaction zone The position of the nozzle for introducing the inorganic or metallic material into the reaction zone is adjustable, and the base material to be introduced into the flow of ultrafine particles. A plurality of inlets of the base material are attached to the device in advance, and the base material is introduced from any one or a plurality of base material inlets to achieve the desired purpose, and the other inlets are not used. By introducing It can be formed.

The present invention described above will be described in more detail with reference to the drawings.

FIG. 1 shows an apparatus of the present invention in which a base material supply nozzle is movably constructed. In the figure, A is a plasma torch part, B is a reaction zone part composed of a quartz double tube, C is a chamber part composed of a stainless double tube,
D is an ultrafine particle raw material feeder, E is a base material raw material feeder, F
Is a product recovery unit and G is a movable base material supply nozzle.

Plasma torch A has an inner diameter of 44 mm and a length of 15
Mainly consists of a 0 mm quartz tube (1), a coil (2) for high frequency oscillation is attached to the outside, and a jacket tube for cooling is attached to the outside.
(3) is provided. Gas outlets in the tangential, axial and radial directions above the plasma torch
(4), (5) and (6) are provided, and 30 l / min of argon is supplied to the jet outlets from gas supply sources (7), (8) and (9). This jetted gas is a high frequency power source of 4MHz, 40K
It is turned into plasma by VA and forms a plasma flame in the plasma torch.

The ultrafine particle raw material introduced from the ultrafine particle raw material supply device D is discharged to the lower part of the plasma torch A together with the carrier gas flow indicated by the arrow, and is contacted with the plasma flame to be vaporized. When the ultrafine particle raw material is a gas body, for example, methane gas, methane gas is introduced without passing through D together with the carrier gas flow. On the other hand, the base material raw material particles supplied from the base material raw material supply device E are carried by the carrier gas flow indicated by the arrow and discharged into the reaction zone B through the movable base material supplying nozzle. This base material supply nozzle is a stainless steel nozzle having an outer diameter of φ6 and an inner diameter of φ4, and a temperature detector is provided at the tip of the nozzle so that the nozzle position can be adjusted while measuring the temperature at the base material supply position.

The temperature distribution in the reaction zone greatly depends on plasma generation conditions, carrier gas flow rate, type, coil shape, chamber shape and the like. By using this device, the base material particles can be supplied to a temperature range suitable for coating, and efficient coating can be performed.

FIG. 2 shows another embodiment of the apparatus of the present invention in which a plurality of base material inlets are preliminarily attached to the apparatus. In the drawing, the meanings of A to F and 1 to 9 are the same as those in FIG. In the apparatus shown in this figure, the base material is introduced from the base material raw material supply device E, but the conduit is, for example, the valve 1
It is a manifold line with 0 to 12 valves 10
The matrix introduced by operation 12 can be charged at any location in the reaction zone with the carrier gas stream. In this drawing, there are four base material inlets, but it is also possible to use a smaller number or a larger number than this, and further connect each inlet directly to each base material feed device E. Is also good.

According to the present invention, an inorganic material or a metal material whose surface is coated with ultrafine particles can be obtained. As the inorganic material or metal material of the base material whose surface is coated with the ultrafine particles, a refractory or a ceramic is used. All inorganic substances called, eg oxides Al ₂ O ₃ , ZrO ₂ , S
S that is a nitride such as iO ₂ , BeO, MgO, and CaO
i ₃ N ₄ , AlN, BN, and other carbides such as SiC and WC
Etc., various clay minerals such as BP and BN that are boride, for example, kaolin, montmorillonite, bentonite, vermiculite, various magnetic materials such as ferrite, simple elements, for example, diamond, graphite, etc.
Simple metals such as Si, Ni, Co, W, Ti, Al, C
u, Fe, etc., and intermetallic compounds and alloys, such as Fe-Ni-Si alloys, Fe-Cr-Al alloys, Fe-
Materials such as Cr-Mo alloys, Fe-Ni-Cr alloys, Ni-Cr alloys, etc., and powders of a composite of these materials can be mentioned.

The particles of the inorganic or metallic material whose surface is coated with these ultrafine particles are usually powders having a particle size in the range of 0.1 μm to 100 μm, especially 1 μm to 10 μm.
Those in the range of m are preferable in terms of handling operation.

The constituents of the ultrafine particles for coating the surface of the particles of the above-mentioned inorganic material or metal material have a surface which depends on the desired properties and functions of the obtained particles coated with the surface. and be coated particles is a variety of inorganic materials or metallic materials or different are identical, as these embodiments, various inorganic materials, Al ₂ O _3, for example oxides, SiO _2, ZrO ₂ , Y
₂ O ₃ , CaO and other nitrides such as Si ₃ N ₄ , AlN and B
N, etc., carbides such as WC, SiC, etc., boronides, such as BP, BN, etc., elemental metals such as Si, Al, N
Examples include simple nonmetallic substances such as i, Co, Cu, Fe, Ti, and W, such as C and B, and various intermetallic compounds and alloys, and composites of these materials.

According to the present invention, when the base material particles of the inorganic or metal material are coated with the ultrafine particles of the inorganic or metal material, the adhesion strength of both particles is adjusted and the base material particles are damaged by heat by the above-mentioned constitution. The prevention of thermal damage in the case of easy materials and the amount of ultrafine particles coated could be controlled by adjusting the contact time of both particles.

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 This example was carried out using the apparatus described in FIG. In this example, diamond particles (40 to 60 μm) were coated with ultrafine silver particles. Plasma is 4MHz in coil 2, 40KVA
Was applied to the plasma torch A from 7, 8 and 9 at a flow rate of 30 l / min to generate plasma gas.

From the ultrafine particle raw material supply device D, raw material metallic silver (particle size: 2 μm) was supplied at a supply rate of 1.3 g / min while being carried by 7 l / min of argon as a carrier gas.

On the other hand, the base material diamond (particle size 40 to 40
60 μm) was supplied from the base material raw material supply device E while being supported on the carrier gas argon of 11 l / min at a supply amount of 4.0 g / min.

By adjusting the position of the nozzle, the base material supply position is set to: 200 mm below the coil (temperature about 2000 ° C.): 250 mm below the coil (temperature about 1000 ° C.): 300 mm below the coil (temperature about 500 ° C.) .

The diamond thus coated with silver was removed from F and analyzed by X-ray diffraction.

A graphite peak was observed in the coated diamond of (1) and a graphite peak was not observed in the coated diamond of (3). From this, it can be seen that the base material diamond is damaged by heat.

When the wettability of the base material and the ultrafine silver particles was observed with an electron microscope, the contact angle was θ = 45 °, and the contact angle was θ.
It was found that the wettability of the thing which was found to be = 80 °,: θ = 110 ° was the largest.

Example 2 This example was also performed using the apparatus described in FIG. In this example, silicon nitride was coated with Y ₂ O ₃ . For plasma, a high-frequency current of 4 MHz and 40 KVA was applied to the coil 2, and 10 l / min of oxygen and 10 l / m of oxygen were used as plasma gas.
It was generated by flowing it into the plasma torch A from 7, 8 and 9 at a flow rate of in.

Yttrium Y (particle size: 100 μm) as a simple substance was supplied from the ultrafine particle raw material supply device D while being supported on 7 l / min of argon as a carrier gas at a supply amount of 0.3 g / min.

On the other hand, the base material particles of silicon nitride Si ₃ N ₄ (particle size 1 μm) were supplied while being supported on argon of carrier gas at a rate of 2.1 g / min.

By adjusting the position of the nozzle, the base material supply position is set to: 450 mm below the coil (temperature about 1800 ° C.): 550 mm below the coil (temperature about 1000 ° C.): 650 mm below the coil (temperature about 500 ° C.) .

When the silicon nitride coated with yttrium oxide Y ₂ O ₃ was taken out from the bottom and analyzed by X-ray diffraction, a peak of silicon oxide was observed in the coated silicon nitride. No peak of silicon oxide was observed. From this, it can be seen that silicon nitride was thermally damaged to be silicon oxide.

The particle size of the coated ultrafine particles was measured by an electron microscope and found to be 25 to 10 nm, 30 to 15 nm, and 60 to 30 nm.

[Brief description of drawings]

FIG. 1 illustrates one embodiment of an apparatus for practicing the present invention.

FIG. 2 is a diagram showing another specific example of the apparatus for carrying out the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadashi Tadashi 2-23-16 Midorigaoka, Oi-cho, Iruma-gun, Saitama (72) Inventor Satoshi Akiyama 17-22 Inari-cho, Kawagoe-shi, Saitama 202 (72) Inventor Miaki Hamada 3-4-8 Suehiro-cho, Kawagoe-shi, Saitama (72) Inventor Eisuke Kuroda 2-16-4 Nishikosenba-cho, Kawagoe-shi, Saitama (72) Inventor Kaoru Umeya Yagiyamamoto-cho, Taishiro-ku, Sendai-shi, Miyagi 1-30-13 (72) Inventor Tadakatsu Nabeya 1095-21 Yamanouchi, Kamakura, Kanagawa Prefecture (72) Inventor Yukio Sumida 55-520 Nakahara Yoshida, Watari Town, Watari District, Miyagi Prefecture Inventor Etsuo Toyama Kitakanbara District, Niigata Prefecture 3418 Manohara, Shiunji-cho, Oita, Japan (72) Kenichi Kimura 2-33-5 Yagiyamahonmachi, Taihaku-ku, Sendai City, Miyagi Prefecture Grace Yagiyama No.502

Claims (2)

[Claims] 1. A base material particle of an inorganic material or a metal material, wherein a flow of ultrafine particles of an inorganic material or a metal material is generated by a vapor phase method, and the surface of the ultrafine particles is coated with the ultrafine particles in the flow of the ultrafine particles. In the method of coating the surface of the base material particles with the ultrafine particles by bringing the ultrafine particles and the particles of the base material into contact with each other in a fluidized state, the method of changing the introduction position of the base material particles . 2. An apparatus for generating a flow of ultrafine particles of an inorganic material or a metal material by a vapor phase method, and a base material of an inorganic or metal material whose surface is to be coated with the ultrafine particles in the flow of the ultrafine particles. And a device adapted to bring the ultrafine particles and the base material particles into contact with each other in a fluidized state, and the base material particle charging device is configured to change the introduction position of the base material particles. An apparatus for producing particles in which the surface of base material particles of an inorganic material or a metal material is coated with ultrafine particles of an inorganic material or a metal material.