JP2005336562A - Composite of metal and carbon nano-fiber, and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite of a metal and a carbon nano-fiber, which has a controlled content of the carbon nano-fiber and a controlled size of the composite, and is suitable for mass production, and to provide a production method therefor. <P>SOLUTION: The composite of metal and carbon nano-fiber is formed by making a molten metal mixed with the carbon nano-fiber, and the compound particulate and solidified. The method for producing the composite of the metal and the carbon nano-fiber comprises making the molten metal flow downward from an efflux opening 14a in an inert gas atmosphere, and spraying a compressed inert gas containing the carbon nano-fiber at a high speed toward the molten metal flowing downward, to mix the molten metal with the carbon nano-fiber and to make the compound particulate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a metal / carbon nanofiber composite and a method for producing the same.

Carbon nanofibers are used for various sliding materials, heat dissipation materials, and the like, for example, as a composite material mixed in a metal. As a method for producing this composite material, a method of adding fine carbon fibers to molten metal, stirring, and mixing is generally considered. However, in the above method, since the specific gravity is greatly different between the metal and the fine carbon fiber and the property that the carbon nanofiber is difficult to wet the molten metal, the fine carbon fiber is uniformly dispersed in the molten metal. There is a problem that it is extremely difficult.
In addition, when the carbon nanofibers are dispersed in the plating solution and electrolytic plating is performed, and the plated product is deposited in granular form, the carbon nanofibers are incorporated into the plated product so that the particles of the metal and the carbon nanofibers are granular. A technology has been developed to obtain a complex of.
However, the above method has a problem that it is not suitable for industrial mass production.
Japanese Patent Application No. 2002-320407

  Therefore, the present invention has been made to solve the above-mentioned problems, and its object is to control the content of carbon nanofibers and the size of the composite, and a metal / carbon nanofiber composite suitable for mass production and its To provide a manufacturing method.

The metal / carbon nanofiber composite according to the present invention is obtained by mixing molten carbon with carbon nanofibers, and pulverizing and solidifying the composite.
The metal is preferably aluminum or an alloy thereof, magnesium or an alloy thereof.

  In addition, the method for producing a metal / carbon nanofiber composite according to the present invention is a method in which a molten metal is caused to flow down from a flow outlet in an inert gas atmosphere, and carbon nanofibers are mixed into the molten metal flowing down. By spraying an inert gas at a high speed, carbon nanofibers are mixed into the molten metal and are made into particles.

In addition, the method for producing a metal / carbon nanofiber composite according to the present invention allows a composite in which carbon nanofibers are mixed in a molten metal to flow down from a flow outlet in an inert gas atmosphere, and directs the composite to the flow down. The composite is made into particles by spraying a compressed inert gas at a high speed.
In the above step, the composite is stored in a closed container, and the closed container is shaken to stir the composite, and the inside of the closed container is pressurized with an inert gas to be combined from a flow outlet provided in the closed container. It is preferable to let things flow down.

Furthermore, in the method for producing a metal / carbon nanofiber composite according to the present invention, in an inert gas atmosphere, a composite in which carbon nanofibers are mixed into a molten metal is placed in a horizontal plane from the flow outlet and below the flow outlet. It flows down on the center part of the rotating disk rotated at high speed, and the composite is scattered in the form of particles around the rotating disk.
The composite is stored in a sealed container, and the sealed container is shaken to stir the composite, and the inside of the sealed container is pressurized with an inert gas, and the composite is allowed to flow down from a flow outlet provided in the sealed container. It is preferable to do so.

  ADVANTAGE OF THE INVENTION According to this invention, the content of a carbon nanofiber and the magnitude | size of a composite can be controlled, and the metal and carbon nanofiber composite suitable for mass production and its manufacturing method can be provided.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an explanatory diagram illustrating an example of the manufacturing apparatus 10. Hereinafter, the manufacturing method of a composite body is demonstrated with description of this manufacturing apparatus 10. FIG.
Reference numeral 12 denotes a high-frequency melting furnace having a known structure, for example, which is supported by a member (not shown) so as to be tiltable, and melts the charged metal.
Reference numeral 14 denotes a storage tank having a flow-down port 14a. The molten metal is supplied from the high-frequency melting furnace 12, and the molten metal is flowed downward from the flow-down port 14a by a required amount.

The high-frequency melting furnace 12 and the storage tank 14 are disposed in a sealed box 16. Reference numeral 17 denotes an exhaust port, and 18 denotes an air supply port. The air in the sealed box body 16 is discharged from the exhaust port 17, and an inert gas such as nitrogen or argon is supplied from the air supply port 18 into the sealed box body 16. It is like that. 17a and 18a are valves. Reference numeral 16a denotes a lid.
During operation, the sealed box 16 is filled with an inert gas.

Reference numeral 20 denotes an atomizing chamber provided below the downflow port 14a, and is provided in a cylindrical shape so as to cover the downside of the downflow port 14a. A collecting chamber 21 is provided at the lower end of the atomizing chamber 20. 21a is a valve.
Reference numeral 22 denotes a compressed gas supply pipe, the tip side of which is disposed immediately above the storage tank flow lower port 14a and jets compressed gas toward the flow lower port 14a. The tip is formed in the nozzle 23.

  The other end of the compressed gas supply pipe 22 is connected to a mixer 24 that mixes carbon nanofibers and an inert gas such as argon. A predetermined amount of an inert gas is supplied to the mixer 24 from an inert gas tank 25 such as high-pressure argon via a pressure regulator 26 and a flow rate adjustment valve 27, and at the same time, a required amount is supplied from a tank 28 storing carbon nanofibers. Each carbon nanofiber is supplied. The carbon nanofiber storage tank 28 is filled with carbon nanofibers mixed with a volatile liquid such as alcohol, and this mixed liquid is supplied from an inert gas tank 29 such as high-pressure argon via a pressure adjustment valve 30. It is pushed out of the storage tank 28 by the inert gas and supplied to the mixer 24 through the flow rate adjusting valve 31.

The inert gas mixed with carbon nanofibers is blown out from the nozzle 23 through the pipe 22 connected to the mixer 24.
For example, the nozzle 23 blows out the inert gas together with the carbon nanofibers at a high speed along the flow of the molten metal flowing in a thin line from the flow-down port 14a. By doing so, the molten metal is granulated by the principle of spraying, and at the same time, carbon nanofibers are taken into the molten metal that has been granulated.

As described above, the molten metal that has been granulated at the same time as the required amount of carbon nanofibers is taken in is solidified while falling in the atomizing chamber 20 and is collected in the collecting chamber 21 as a granular composite.
A cyclone 32 is connected to the lower part of the atomizing chamber 20 and collects residual carbon nanofibers floating in the atomizing chamber 20 and collects them from the pipe 33. A collection chamber 34 is also provided below the cyclone 32, and a relatively small-diameter composite is collected. 21a and 34a are valves.

  An inert gas supply pipe 35 is connected to the atomizing chamber 20. The inside of the atomizing chamber 20 can be purged with an inert gas using the inert gas supply pipe 35 and the cyclone 32. 33a and 35a are valves.

During production (operation) of the composite, the inside of the sealed box 16 and the inside of the atomizing chamber 20 are maintained in an inert gas atmosphere.
The metal is preferably a metal having a relatively low melting point such as aluminum or an alloy thereof, magnesium or an alloy thereof, but is not limited thereto.
The size of the resulting composite can be adjusted by adjusting the flow rate of the molten metal flowing down and the speed of the compressed inert gas blown from the nozzle 23. Finer particles can be obtained by increasing the speed.
The size (diameter) of the composite is not particularly limited, and it can be manufactured from several tens of μm to several mm.

  Further, the amount of carbon nanofibers mixed can be controlled by measuring and adjusting the amount of carbon nanofibers supplied into the mixer 24 with a flow meter or the like. Of course, not all of the supplied carbon nanofibers are taken into the molten metal, and a considerable amount is recovered through the cyclone 32, so the relationship between the supplied amount and the amount taken in is measured and grasped in advance. Good.

  In the above, the carbon nanofibers are taken together with the compressed inert gas into the molten metal flow so as to be blown into the flowing molten metal flow. It may be supplied and mixed in the molten metal, and the composite of the molten metal and the carbon nanofiber may be caused to flow down from the flow-down port 14a. Therefore, in this case, the compressed gas supply pipe 22 is sprayed toward the composite that flows only the inert gas. By doing in this way, since carbon nanofiber can be reliably mix | blended in molten metal, the content of carbon nanofiber in the composite obtained can be controlled more accurately.

2 and 3 show another embodiment of the high-frequency melting furnace 12. FIG. 2 is a front view, and FIG. 3 is a bottom view.
In this embodiment, the high-frequency melting furnace 12 is formed of a sealed container, and a flow-down port 14a is provided at the center of the bottom of the high-frequency melting furnace 12 (FIG. 3). Therefore, the high-frequency melting furnace 12 forms an integral structure with the storage tank 14 shown in FIG.
Then, a frame-like body 40 is attached to the lower part of the sealed container so as to surround the flow-down port 14 a, pivot shafts 41 are attached to both sides of the frame-like body 40, and the pivot shaft 41 is attached to the wall portion of the sealed box body 16. Thus, as shown by the arrows in FIG. 2, the melting furnace 12 is reciprocally turned up and down at a required angle across the horizontal axis in the vertical plane. Reference numeral 42 denotes a driving motor. When the melting furnace 12 is rotated, the line connecting both the rotating shafts 41 is made to pass through the flow-down port 14a so that the position of the flow-down port 14a is always constant.

  In the present embodiment, the melting furnace 12 composed of the above-mentioned sealed container is arranged at the position of the storage tank 14 in FIG. Then, in the same manner as described above, carbon nanofibers are supplied in advance into the high-frequency melting furnace 12 and mixed in the molten metal, and while the melting furnace 12 is swung and rotated as described above, The composite with the fiber is allowed to flow down from the flow down port 14a. The flow-down port 14a is closed by a compressed inert gas supply pipe 22 until an appropriate time during which the composite of molten metal and carbon nanofibers is uniformly mixed. Then, after a predetermined time has elapsed, the pipe 22 is raised and opened, and at the same time, a compressed inert gas is ejected from the nozzle 23, and the composite of molten metal and carbon nanofibers is caused to flow down from the flow down port 14a.

In this way, by shaking the melting furnace 12 and stirring the contents, the carbon nanofibers can be uniformly dispersed in the molten metal, so that a composite in which the carbon nanofibers are mixed more uniformly is obtained. Can do it. In particular, when the molten metal is aluminum, brittle aluminum carbide is generated at the interface between the two when it is in contact with the carbon nanofibers, which reduces the strength of the carbon nanofibers when formed into a composite. Stirring is preferable because growth of aluminum carbide is suppressed.
It is preferable that the melting furnace 12 is reciprocally swung in the vertical plane as described above because the stirring effect is high and good, but it may be reciprocated in a horizontal plane. Or you may comprise in the composite-type rocking | fluctuation mechanism rock | fluctuated both in a vertical surface and a horizontal surface.

FIG. 4 shows still another embodiment of the manufacturing apparatus 10. The same members as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.
In this embodiment, the molten metal is not granulated by the spraying method as described above, but is granulated by the so-called centrifugal atomization method. For this purpose, a rotating disk 45 that rotates at high speed in a horizontal plane is disposed below the flow-down port 14a in the atomizing chamber 20. Reference numeral 46 denotes a driving unit which is supported in the atomizing chamber 20 by a support arm 47.
The rotating disk 45 is fixed to a shaft 50 rotated by a drive motor 49 disposed in a motor box 48, and is rotated in a horizontal plane.

In this embodiment, in an inert gas atmosphere, the molten metal is caused to flow down from the flow-down port 14a onto the center of the rotating disk 45 that rotates at high speed in a horizontal plane below the flow-down port 14a. As a result, the molten metal scatters around the rotating disk 45 in a granular form. And the magnitude | size of the composite_body | complex obtained can be adjusted by adjusting the flow rate of the molten metal which flows down from the flow-down opening 14a, and the rotational speed of the rotating disc 45. FIG. By increasing the rotation speed of the rotating disk 45, finer particles can be obtained.
The size (diameter) of the composite is not particularly limited, and it can be manufactured from several tens of μm to several mm.

It is explanatory drawing which shows the Example of the manufacturing apparatus of a composite_body | complex. It is a front view which shows the other Example of a high frequency melting furnace. It is a bottom view of the high frequency melting furnace of FIG. It is explanatory drawing which shows the other Example of the manufacturing apparatus of a composite_body | complex.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Manufacturing apparatus 12 High frequency melting furnace 14 Storage tank 16 Sealed box 17 Exhaust port 18 Air supply port 20 Atomization chamber 21 Collection chamber 22 Compressed inert gas supply pipe 23 Nozzle 24 Mixer 25 High-pressure inert gas tank 26 Pressure regulator 27 Flow adjustment valve 28 Storage tank 29 High-pressure inert gas tank 30 Pressure regulator 31 Flow adjustment valve 32 Cyclone 34 Collection chamber 45 Rotating disk 46 Drive part

Claims (10)

  A metal / carbon nanofiber composite in which carbon nanofibers are mixed into molten metal, and the composite is made into particles and solidified.   The metal / carbon nanofiber composite according to claim 1, wherein the metal is aluminum or an alloy thereof.   The metal / carbon nanofiber composite according to claim 1, wherein the metal is magnesium or an alloy thereof.   In an inert gas atmosphere, the molten metal is caused to flow down from the flow outlet, and the carbon nanofibers are applied to the molten metal by spraying the compressed inert gas mixed with the carbon nanofibers toward the flowing molten metal at a high speed. A method for producing a metal / carbon nanofiber composite comprising mixing and particleizing.   In an inert gas atmosphere, a composite in which carbon nanofibers are mixed with molten metal is allowed to flow down from a flow outlet, and a compressed inert gas is blown at a high speed toward the flowing down composite to thereby remove the composite into particles. A method for producing a metal / carbon nanofiber composite, characterized in that:   The composite is stored in a sealed container, and the sealed container is shaken to stir the composite, and the inside of the sealed container is pressurized with an inert gas, and the composite is allowed to flow down from a flow outlet provided in the sealed container. The method for producing a metal / carbon nanofiber composite according to claim 5.   In an inert gas atmosphere, a composite in which carbon nanofibers are mixed with molten metal is allowed to flow down from the flow outlet to the center of a rotating disk that rotates at high speed in a horizontal plane below the flow outlet. A method for producing a metal / carbon nanofiber composite, wherein the metal / carbon nanofiber composite is dispersed in a granular form around a rotating disk.   The composite is stored in a sealed container, and the sealed container is shaken to stir the composite, and the inside of the sealed container is pressurized with an inert gas, and the composite is allowed to flow down from a flow outlet provided in the sealed container. The method for producing a metal / carbon nanofiber composite according to claim 8.   The method for producing a metal / carbon nanofiber composite according to any one of claims 4 to 9, wherein the metal is aluminum or an alloy thereof.   The method for producing a metal / carbon nanofiber composite according to any one of claims 4 to 9, wherein the metal is magnesium or an alloy thereof.

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