WO2010024475A1

WO2010024475A1 - Method for producing nano carbon-metal composite powder

Info

Publication number: WO2010024475A1
Application number: PCT/KR2008/004945
Authority: WO
Inventors: Jin-Chun Kim; Ji-Soon Kim; Young-Soon Kwon
Original assignee: University Of Ulsan Foundation For Industry Cooperation
Priority date: 2008-08-25
Filing date: 2008-08-25
Publication date: 2010-03-04

Abstract

A method for producing nano carbon-metal composite powder comprising the steps of mixing nano carbon and a fluid to prepare a slurry, electrically exploding a metal wire in the slurry, and drying the fluid contained in the slurry is provided. According to the method for producing nano carbon-metal composite powder of the present invention, as the result of exploding a metal wire in the slurry, metal powder behaving as a composite phase can essentially be protected from oxidation, the metal powder does not coagulate but forms fine powder of nanometer (nm) scale, and the resulting nano carbon-metal composite powder containing an alloy metal powder as a matrix phase and a fluid thereof can be produced in a very economic way using a two or more component alloy metal wire.

Description

Title: METHOD FOR PRODUCING NANO CARBON-

METAL COMPOSITE POWDER

TECHNICAL FIELD The present invention relates to a method for producing nano carbon- metal composite powder, and more particularly, to a method for producing nano carbon-metal composite powder, through which metal powder can essentially be protected from oxidation, the metal powder does not coagulate but forms fine powder of nanometer (nm) scale, and alloy metal powder containing two or more components can be mixed with nano carbon in a very economic way.

BACKGROUND ART

Nano carbons come in form of carbon nanotubes and carbon nanofibers.

The carbon nanotube has a configuration similar to a hollow tube (or cylinder) forming a grapheme pattern where each carbon atom is bonded to its three other neighboring carbon atoms. Depending on the structure of carbon atoms, carbon nanotubes may act as an electric conductor such as metals, or a semiconductor. Such a carbon nanotube is known to have high electrical conductivity similar to copper, high thermal conductivity similar to diamond that is known to have the highest thermal conductivity in the physical world, and excellent hardness that is 100 times higher than that of steel. While carbon fiber is easily cut even after deforming only 1%, carbon nanotube can withstand deformation as much as 15%.

These unique properties of carbon nanotubes have drawn a lot of attention and a large number of studies on the synthesis and applications of carbon nanotubes are now actively in progress. Moreover, numerous devices using carbon nanotubes, e.g., semiconductors, flat displays, batteries, ultra- intense fibers, biosensors, television Braun tubes, etc., have been developed, and a complexification process of heterogenous matters into those carbon nanotubes is another industrial field for which ongoing studies are being conducted by many researchers.

The complexification of carbon nanotubes involves a complexification process of existing micrometer-size metal materials into an only several nanometer-scale carbon nanotube, and a coating or dispersing process of metals and inorganic materials over the nano layer of a carbon nanotube.

The complexification process is made it possible by applying a vapor state reaction for depositing addition elements directly onto a carbon nanotube, a liquid state reaction for causing a chemical reaction such as precipitation or the like, and a solid state reaction such as mechanical plating. However, low reactivity of the carbon nanotube, mixture heterogeneity between carbon nanotubes and nanometer-scale metal powder, and the difficulty in control over the growth and oxidation of metal powder being added remain as limitations to overcome to make metal powder particles as small as 0.1 micrometer in size.

DISCLOSURE TECHNICAL PROBLEM

It is, therefore, an object of the present invention to provide a method for producing nano carbon-metal composite powder, through which metal powder can essentially be protected from oxidation, the metal powder does not coagulate but forms fine powder of nanometer (nm) scale, and alloy metal powder containing two or more components can be mixed with nano carbon in a very economic way.

Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

TECHNICAL SOLUTION

In accordance with an aspect of the present invention, there is provided a method for producing nano carbon-metal composite powder, which includes the steps of mixing nano carbon and a fluid to prepare a slurry, electrically exploding a metal wire in the slurry, and drying the fluid contained in the slurry.

For the preparation step of a slurry, the WC powder is mixed in a fluid that is selected from the group consisting of water, hydrogen peroxide, ethanol, ethanol glycol, glycerin, gelatin, engine oil, distilled water, benzene, toluene, saline solution, edible oil, petroleum, and gasoline.

Preferably, at least one polymer dispersant selected from the group consisting of commercially available polymers including, but not limited to, PVP (polyvinylpyrrolidone), PEI (polyethylenimine), PDADMAC (polydiallydimethylammonium chloride), TWIN 80, polyethylene glycol- condensed, glycerin esters of fatty acids, alkanol amides of fatty acids, and so on; or at least one binder selected from the group consisting of low-melting point organic compounds including, but not limited to, acryl, stearic acid, wax, and so on. The nano carbon is preferably selected from the group consisting of carbon nanotubes and carbon nanofibers.

ADVANTAGEOUS EFFECTS The method for producing nano-carbon-metal composite powder has the following advantages.

First, as a result of exploding a metal wire in a fluid, metal powder behaving as a composite phase can essentially be protected from oxidation, and the metal powder does not coagulate but forms fine powder of nanometer (nm) scale.

Second, nano carbon-metal composite powder containing alloy metal powder as a matrix phase and a fluid thereof can be produced in a very economic way using a two or more component alloy metal wire.

Third, nano carbon-metal composite powder is produced by an electric explosion within a fluid, and the resulting powder is advantageous for use in the development of high-strength materials, wide applications as a coating material, an energy material such as a solid catalyst, and so on.

Fourth, the nano carbon-metal composite powder in accordance with the present invention does not need to be dried completely, but can be applied, as a half-dried slurry state, to a coating process such as a tape casting process.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a flow chart describing a method for producing nano carbon- metal composite powder in accordance with one embodiment of the present invention.

Fig. 2 is a view showing a picture of a device used for the method for producing nano carbon-metal composite powder in accordance with one embodiment of the present invention. Fig. 3 is a view showing the state of a slurry in an electric explosion step out of the method for producing nano carbon-metal composite powder in accordance with one embodiment of the present invention.

Fig. 4 is a conceptual view of nano carbon-metal composite powder produced based on the method for producing nano carbon-metal composite powder in accordance with one embodiment of the present invention.

BEST MODE FOR THE INVENTION

Hereinafter, a preferred embodiment of the present invention will be explained in detail with reference to accompanying drawings. Before the present method is disclosed and described, one should notice that the terminology used in the specification and any of the claims are not to be interpreted by general meaning commonly known to an ordinary skilled person in the art or definitions in dictionary only, but should be understood as meaning and concept suitable for technical idea of the present invention, on the basis of the principle that an inventor is able to define the concept of a certain term for the purpose of describing his invention in the best way.

Therefore, the embodiments described herein and the construction illustrated in the drawings are for the purpose of describing a particular embodiment only, and are not intended to be limiting or representing all the technical ideas the present invention try to convey. Therefore, one should notice that there are many alternatives, modifications, and variations that can act as a substitute for them at the time of filing.

The following will now explain a method for producing nano carbon- metal composite powder in accordance with one embodiment of the present invention, with reference to Figs. 1 through 4.

Fig. 1 is a flow chart describing a method for producing nano carbon- metal composite powder in accordance with one embodiment of the present invention; Fig. 2 shows a picture of a device used for the method for producing nano carbon-metal composite powder in accordance with one embodiment of the present invention; Fig. 3 shows the state of a slurry in an electric explosion step out of the method for producing nano carbon-metal composite powder in accordance with one embodiment of the present invention; and Fig. 4 is a conceptual view of nano carbon-metal composite powder produced based on the method for producing nano carbon-metal composite powder in accordance with one embodiment of the present invention.

The method for producing nano carbon-metal composite powder includes a slurry preparation step (S110), an electric explosion step (S120), a drying step (S130), and a collection step (S140). The slurry preparation (S110) is a process where nano carbon is mixed with a fluid to produce a slurry. Here, examples of the fluid may include, but are not limited to, water, hydrogen peroxide, ethanol, ethanol glycol, glycerin, gelatin, engine oil, distilled water, benzene, toluene, saline solution, edible oil, petroleum, and gasoline, which are used singly or in combination of two or more. The nano carbon may be either a carbon nanotube or a carbon nanofiber.

Moreover, a dispersant may be added for a fine and homogeneous dispersion of the nano carbon in the fluid. Examples of such a dispersant may include, but are not limited to commercially available polymers including, but not limited to, PVP (polyvinylpyrrolidone), PEI (polyethylenimine), PDADMAC (polydiallydimethylammonium chloride), TWIN 80, polyethylene glycol- condensed, glycerin esters of fatty acids, and alkanol amides of fatty acids, which are used singly or in combination of two or more.

Further, a binder may be added to increase bond strength between metal powder discharged from the electric explosion step (S120, to be described) and the nano carbon. Examples of such a binder may include, but are not limited to, low-melting point organic compounds including, but not limited to, acryl, stearic acid, and wax, which are used singly or in combination of two or more. The electric explosion (S120) is a process where electric power is supplied to a cobalt metal wire in the slurry to cause electric explosion. When electric power is supplied to a metal wire, the metal wire is exploded through melting, discharge, and vaporization of metal due to the generated heat, and the metal pulverization proceeds. In accordance with one embodiment of the present invention, the electric explosion step (S120) is carried out by supplying 0.5-2OkV electric power to the metal wire for a period of time from several micro seconds to several tens of minutes.

As an example, the electric explosion step (S120) is carried out using a device shown in Fig. 2. Here, the metal wire may be made out of a metal selected from the group consisting of cobalt (Co), iron (Fe), and copper (Cu), which are used singly or in combination or two or more.

To explain in more details with reference to Fig. 3, in the slurry preparation step (S110), nano carbon 110 and a fluid 130 are mixed together to prepare a slurry, and a metal line 120 is placed in the slurry. When electric power is applied to the metal line 120, metal powder 121 is discharged from the metal wire 120 into the fluid 130.

For example, in case of using a cobalt metal wire, cobalt metal powder is discharged into the fluid. Meanwhile, in case of using an alloy metal wire containing cobalt and iron, cobalt and iron metal powders are discharged into the slurry. The resulting metal powder binds with nano carbon.

Fig. 4 depicts the configuration of nano carbon-metal composite powder formed from the electric explosion (S120). As can be seen in Fig. 4, the nano carbon and the metal powder are blended homogeneously in the nano carbon- metal composite powder.

In accordance with the present invention, the electric explosion within the fluid serves to prevent the growth of the metal powder or the oxidation thereof, such that the nanometer-scale metal powder may be discharged from the metal wire.

The drying process (S130) is for drying the fluid used for the slurry preparation (S130). In accordance with one embodiment of the present invention, the fluid is heated at a temperature higher than the evaporation point of the fluid to vaporize the fluid. However, the present invention is not limited thereto, but any other method for drying the used fluid can also be utilized.

The collection process (S 140) is for collecting the remaining nano carbon-metal composite powder after the fluid has been dried or evaporated through the drying process (S130). The collected nano carbon-metal composite powder may be advantageously used as a raw material for manufacturing carbide tools, abrasion resistant parts, and die products.

In the coating process (S150), the nano carbon-metal composite powder is coated directly over a target object by tape casting, for example, in use of the slurry not completely dried but with 1-90 vol% of the evaporated fluid. While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A method for producing nano carbon-metal composite powder, comprising the steps of: a) mixing nano carbon and a fluid to prepare a slurry; b) electrically exploding a cobalt metal wire in the slurry; and c) drying the fluid contained in the slurry.

2. The method of claim 1 , wherein the slurry preparation step is carried out in presence of a polymer dispersant selected from the group consisting of commercially available polymers including, but not limited to, PVP (polyvinylpyrrolidone), PEI (polyethylenimine), PDADMAC (polydiallydimethylammonium chloride), TWIN 80, polyethylene glycol- condensed, glycerin esters of fatty acids, and alkanol amides of fatty acids, which are used singly or in combination of two or more; or in presence of a binder selected from the group consisting of low-melting point organic compounds including, but not limited to, acryl, stearic acid, and wax, which are used singly or in combination of two or more.

3. The method of claim 1 , wherein the nano carbon is selected from the group consisting of carbon nanotubes and carbon nanofibers.

4. The method of claim 1 , wherein the fluid is selected from the group consisting of water, hydrogen peroxide, ethanol, ethanol glycol, glycerin, gelatin, engine oil, distilled water, benzene, toluene, saline solution, edible oil, petroleum, and gasoline, which are used singly or in combination of two or more.