KR20190012036A - Method for preparing CNT-coated copper particle using stirred ball mill - Google Patents

Abstract

The present invention relates to a method to manufacture a copper particle coated with a carbon nanotube (CNT) using a stirring ball mill, which includes a step of inserting CNT powder and metal powder into the stirring ball mill to perform stirring ball milling. According to the present invention, a low speed/long time stirring ball milling process with the rotating speed and processing time of a predetermined range is performed to coat the CNT on a surface of a copper particle, thereby manufacturing the copper particle with a high quality CNT coating layer at high efficiency. Moreover, the copper particle coated with the CNT manufactured by such manufacturing method has a uniformly coated CNT coating layer formed on the surface, and simultaneously aims material reduction, lightweight property, and function improvement in comparison with an existing CNT/copper complex material manufactured by simply mixing heterogeneous powders.

Description

[0001] The present invention relates to a method for preparing a copper particle coated with carbon nanotubes using a stirring ball mill,

The present invention relates to a method for producing a carbon nanotube / copper composite material.

Recently, studies on the production of metal-based carbon nanotube (CNT) composites have been diversified in response to demands for lightweight and highly functional materials. Carbon nanotubes have various physical properties such as light weight, high strength, flexibility, high electrical conductivity, high thermal conductivity, heat resistance, electromagnetic wave absorption and chemical stability. Copper is a well-known material widely used as an electrically conductive material. However, when the cross-sectional area is reduced, the tensile strength is weakened and the required amount of current is also weakened. In contrast, nano-sized thin multilayered carbon nanotubes can pass 1,000 times more current than copper. In addition, the copper powder having a small cross-sectional area generally has a characteristic that it is scattered when electrons move and can not move quickly because of high electrical resistance. However, in the case of carbon nanotubes, electrons can pass quickly without scattering, resulting in less resistance. Thus, a composite material of copper powder and carbon nanotube powder has many advantages in use in various industries.

However, carbon nanotube / copper composite materials having a structure in which carbon nanotubes are coated on the surface of copper particles and a method for producing the same are not known in advance, and research and development thereof are required.

Korean Patent Publication No. 10-2005-0037877 (published on April 25, 2005) Korean Patent Publication No. 10-2010-0024230 (published on March 30, 2010) Korean Patent Publication No. 10-2011-0027181 (Published Date: March 16, 2011)

The present invention provides a method for producing a carbon nanotube / copper composite material having a structure in which carbon nanotubes are coated on the surface of copper particles.

In order to accomplish the above object, the present invention provides a process for producing a carbon nanotube (CNT) powder and a copper (Cu) powder by stirring the powder mixture at a rotation speed of 50 to 200 rpm for at least 12 hours ball milling to coat the carbon nanotubes on the surfaces of the copper powder particles.

Also, there is provided a method for producing carbon nanotube-coated copper particles, characterized in that stirring ball milling is performed for 12 to 48 hours at a rotation speed of 50 to 100 rpm.

Also, the mixed powder includes a carbon nanotube powder and a copper powder in a weight ratio of 0.5: 99.5 to 5: 95.

Also, the present invention provides a method for producing copper nanoparticles coated with carbon nanotubes, wherein the average particle diameter of the copper nanoparticles is 1 to 6 mu m.

The present invention also provides a method for producing carbon nanotube-coated copper particles, characterized in that agitated ball milling is performed using a ball made of alumina, zirconia, or stainless steel.

Also, there is provided a method for producing carbon nanotube-coated copper particles, characterized in that agitated ball milling is performed using a ball having a diameter of 2 to 10 mm.

The present invention also provides a process for producing copper nanoparticles coated with carbon nanotubes, wherein stirring ball milling is carried out at a weight ratio of the balls to the mixed powder of 15: 1 to 5: 1.

The present invention also provides a process for producing carbon nanotube-coated copper particles, characterized in that stirring ball milling is performed at a ball filling ratio of 0.1 to 0.5.

In another aspect of the present invention, there is provided a carbon nanotube-coated copper particle produced according to the above production method.

According to the method for producing copper particles coated with carbon nanotubes using the stirring ball mill according to the present invention, a low-speed / long-time agitation ball milling process having a specific range of rotation speed and process time is performed, The copper particles containing the carbon nanotube coating layer of high quality and high efficiency can be produced.

In addition, the carbon nanotube-coated copper particles produced by the manufacturing method according to the present invention have a CNT coating layer uniformly coated on the surface thereof and can be produced by a simple mixing of carbon nanotubes / It is possible to simultaneously save the material, reduce the weight, and improve the functionality.

1 is an SEM photograph showing the shape of raw material powders ((a) -copper powder) and (b) -MWCNT powder used in this embodiment.
FIG. 2 is a graph showing changes in the ball milling rotational speed (500 to 300 rpm) and ball material changes ((a) -alumina, (b) -zirconia , (c) -stainless steel). In the SEM photographs of carbon nanotube / copper composite particles,
FIG. 3 is a graph showing changes in the ball milling rotational speed (500 to 300 rpm) and ball material changes (a) -alumina, (b) -zirconia , (c) -stainless steel). In the SEM photographs of carbon nanotube / copper composite particles,
FIG. 4 is a graph showing the relationship between the ball milling time (12 and 48 hours) and the ball material ((a) -alumina, (b) -zirconia, (c) -stainless steel). Fig. 2 (a) is a FESEM photograph of the surface of a carbon nanotube / copper composite material particle prepared by different methods.
5 is a graph showing the relationship between the ball milling time (12 and 48 hours) and the ball material ((a) -alumina, (b) -zirconia, (c) -stainless steel). Fig. 2 (a) is a FESEM photograph of the surface of a carbon nanotube / copper composite material particle prepared by different methods.
6 is a graph showing the relationship between the ball milling time (12 and 48 hours) and the ball material ((a) -alumina, (b) -zirconia, (c) -stainless steel). Fig. 2 (a) is a FESEM photograph of the surface of a carbon nanotube / copper composite material particle prepared by different methods.
Fig. 7 shows the result of analyzing the actual ball behavior with the camera and the simulation of the ball movement ((a) -alumina ball, (b) -zirconia ball, and (c) -stainless steel ball).
8 is a graph showing the milling efficiency of alumina balls, zirconia balls, and stainless steel balls according to the number of revolutions.
FIG. 9 is a graph showing average ball kinetic energy according to the number of revolutions of each ball material ((a) -50 rpm, (b) -100 rpm, and (c) -300 rpm).

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Embodiments in accordance with the concepts of the present invention can make various changes and have various forms, so that specific embodiments are illustrated in the drawings and described in detail in this specification or application. It should be understood, however, that the embodiments according to the concepts of the present invention are not intended to be limited to any particular mode of disclosure, but rather all variations, equivalents, and alternatives falling within the spirit and scope of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises ", or" having ", or the like, specify that there is a stated feature, number, step, operation, , Steps, operations, components, parts, or combinations thereof, as a matter of principle.

Hereinafter, the present invention will be described in detail.

A method for manufacturing a carbon nanotube / copper composite material according to the present invention is a method for producing a carbon nanotube / copper composite material, which comprises mixing powder containing carbon nanotube (CNT) powder and copper (Cu) powder at a rotating speed of 50 to 200 rpm for at least 12 hours, and then performing stirred ball milling to coat the surface of the copper powder particles with the carbon nanotubes, thereby producing copper particles coated with the carbon nanotubes.

The carbon nanotubes (CNTs) are carbon nanotubes (CNTs) having a hexagonal honeycomb pattern formed into a tube shape. The carbon nanotubes are very anisotropic and have various structures such as a single wall, a multiwall, and a bundle. The carbon nanotubes have nanometer-scale diameters, exhibit excellent mechanical properties, electrical selectivity, excellent field emission characteristics, and high-efficiency hydrogen storage medium characteristics, and can contribute to improvement of physical properties of metals.

The carbon nanotubes can be used without limitation in the form of a single wall, a multiwall, a bundle, or the like. Preferably, the carbon nanotube is a multiwall carbon nanowire having low density, excellent corrosion resistance, abrasion resistance, Tubes can be used.

The copper powder is not limited to the particle size but may be copper powder having various particle sizes with an average particle size uniform. Preferably, the copper powder having an average particle size of 1 to 6 탆 may be used. By forming the carbon nanotube coating layer on the surface of the powder by stirring ball milling, composite material particles smaller than the crystal grains of carbon nanotubes and copper composite sintered bodies manufactured by the conventional sintering method can be formed, Fine grain size can be achieved and a fine copper composite material having excellent strength can be produced.

In the present invention, in order to produce a copper composite material including a carbon nanotube coating layer through a stirring ball milling process, the carbon nanotube powder and the copper powder are charged into the stirring ball mill at a weight ratio of 0.5: 99.5 to 5: 95 , And the carbon nanotubes may be complexed with copper powder to produce a composite material.

When the weight ratio of the carbon nanotube powder and the copper powder is less than 0.5: 99.5, the content of the carbon nanotubes is low, so that the coating layer is not sufficiently formed in the entire copper powder, so that the coating layer is only partially formed. , The physical properties of the carbon nanotubes can not be increased any more, so that the copper composite material including the carbon nanotube coating layer can be manufactured by stirring ball milling in the weight ratio range. Preferably, the carbon nanotubes and the copper powder are mixed at a weight ratio of 1:99 by ball milling to produce a copper composite material.

The stirring ball mill apparatus is an apparatus capable of pulverizing particles by moving a ball by rotation of a stirring blade in a pot and composing two or more kinds of particles, wherein the particles are coated with other particles to produce a composite material And a copper composite material in which a carbon nanotube coating layer is coated on the surface by compositing the carbon nanotube powder and the copper powder can be manufactured.

Therefore, when the carbon nanotube powder and the copper powder are charged into the stirring ball mill apparatus and the stirring ball milling process is performed, the port, the balls, and the balls and the balls in the port of the stirred ball mill apparatus during the ball milling process, Powder and copper powder, and the copper particles and the carbon nanotube particles are pulverized and plastically deformed, so that the carbon nanotube particles are combined on the surface of the copper powder particles, and the carbon nanotube coating layer is formed on the surface of the copper particles.

The ball may have a diameter of 2 to 10 mm, and preferably a ball having an average diameter of 5 mm may be used to perform an agitating ball milling process. Examples of the balls include alumina, zirconia zirconia, stainless steel, and the like.

The weight of the ball and the mixed powder may be adjusted to 15: 1 to 5: 1 to perform a stirring ball milling process. Preferably, the weight ratio of the balls to the mixed powder is set to 10: 1, Process can be performed.

For example, 4 g of a mixed powder obtained by mixing 0.04 g and 3.96 g of the carbon nanotube powder and the copper powder, respectively, is put into a stirring ball mill and a ball having a weight of 40 g is put into the stirring ball milling process.

In addition, it is possible to form a carbon nanotube coating layer on the surface of copper particles by controlling the friction and impact between the balls by performing a stirring ball milling process at a ball filling ratio of 0.1 to 0.5, preferably 0.3 The stirring ball milling process can be performed at the ball filling rate.

The agitation ball milling process is preferably performed at a rotation speed of 50 to 200 rpm for 12 hours or more (more preferably 12 to 48 hours), wherein the rotation speed is less than 50 rpm or the rotation speed is more than 200 rpm If the stirring ball milling process is performed at a high speed, coating of the carbon nanotubes is not smooth and it is difficult to form a copper composite material including a uniform carbon nanotube coating layer. In addition, in the case of performing the stirring ball milling process at less than 12 hours at the above rotational speed, it is difficult to form a uniform carbon nanotube coating layer, and when stirring ball milling process is performed for more than 48 hours, . Preferably 100 rpm, for 12 hours to prepare a copper composite material having a uniform carbon nanotube coating layer. More preferably, the mixture is stirred at a stirring speed of 100 rpm for 48 hours Lt; RTI ID = 0.0 > milling < / RTI >

According to the carbon nanotube-coated copper particle manufacturing method using the stirring ball mill according to the present invention, the low-speed / long-time agitation ball milling process having a specific range of rotation speed and process time is performed, It is possible to produce copper particles containing a high-quality carbon nanotube coating layer with high efficiency.

In addition, the carbon nanotube-coated copper particles produced by the manufacturing method according to the present invention have a CNT coating layer uniformly coated on the surface thereof and can be produced by a simple mixing of carbon nanotubes / It is possible to simultaneously save the material, reduce the weight, and improve the functionality.

Hereinafter, the present invention will be described in more detail with reference to examples. It should be understood, however, that the embodiments shown are only illustrative of the present invention and are not intended to limit the scope of the present invention.

<Examples>

In this embodiment, a stirring ball mill having a port made of stainless steel is used. In order to compare the difference of the grinding media, abrasion resistant alumina, zirconia and stainless steel balls were used as the grinding media, and a ball having a diameter of 5 mm was used. As the samples used in this embodiment, copper powder (Aldrich Co., Ltd., purity: 99.9%, median diameter: 20 μm), which is widely used as a high-strength lightweight alloy material in industrial fields, was used. FIG. 1 is a SEM photograph showing the shapes of raw material powders ((a) -copper powder) and (b) -MWCNT powder used in the present embodiment.

First, when a mixed powder of copper powder and CNT powder containing 1 wt% of CNT is prepared and the balls of the above three materials are used, the total weight of the mixed powder is determined by the ratio of the medium to the sample, that is, BPR Powder Ratio) was set at 10: 1. The rotation speed of each grinding machine was changed by 50, 100, 300 rpm. The milling time was changed to 12, 24 and 48 hours. Table 1 below shows the operating conditions of this embodiment together with the density depending on the type of the medium.

In order to simulate the crushing, ball behaviors of different kinds in the container were observed, and the ball behavior according to the actual rotation speed was photographed as a moving image. DEM simulation was performed through optimal simulation conditions. Table 2 below shows the simulation conditions for this experiment. In order to make the simulation conditions consistent with the actual experimental conditions, all of the conditions were matched under the conditions that can be driven in the software, and the determination of the friction coefficient was made using the existing literature data (B. Bhushan, BK Gupta, Handbook of Tribology: Materials, Coatings , and Surface Treatments, McGraw-Hill, NY., US (1991) and B. Bhushan, Mordern Tribology Handbook, vol.1 Principles of Tribology, CRC Press LLC, .

<Experimental Example>

FIG. 2 is a graph showing changes in the ball milling rotational speed (500 to 300 rpm) and ball material changes ((a) -alumina, (b) -zirconia FIG. 3 is a SEM photograph showing the shape change of the carbon nanotube / copper composite material particles according to the present invention, (c) - (stainless steel) Showing changes in shape of carbon nanotube / copper composite particles according to ball mill rotation speed change (500 to 300 rpm) and ball material changes ((a) -alumina, (b) -zirconia, (c) -stainless steel) SEM picture.

The milling times associated with Figs. 2 and 3 were for a long time (12 hours and 48 hours) for the preparation of the composite material, which is the ultimate objective of this experiment. This is because CNT is added to produce a composite material with copper powder. In the case of manufacturing a composite material, when the milling time is short, CNT serves not only as a material of the composite material but also as a pulverizing auxiliary agent, This is because during milling process, milling plays a strong role in milling, which makes it difficult to produce composites.

According to FIGS. 2 and 3, as the number of revolutions increases, the fraction of powder in the form of a plate type increases with respect to the massive powder, and when the milling is performed for 12 hours (FIG. 2), it was found that the particle shape changed to a perfect plate shape under all the experimental conditions when the milling was performed for 48 hours (FIG. 3). This shows that as the amount of energy input to the sample in the ball ultimately increases, the shape of the particle changes due to the plastic deformation occurring in the sample.

In order to confirm whether or not the carbon nanotube powder and the copper powder were combined through the stirring ball milling process, the surface of the particles produced in the above example was confirmed by using a long-term field emission scanning electron microscope (FESEM) 6.

Referring to FIGS. 4 to 6, it can be seen that a large number of CNTs are uniformly distributed on the surface of the composite material particles obtained through the stirring ball milling at low speed (50 rpm and 100 rpm) (see FIGS. 4 and 5) (300 rpm), it was confirmed that CNT coating was not properly performed on the surface of the composite material particles obtained by stirring ball milling (see FIG. 6).

FIG. 7 shows the result of analyzing the actual ball behavior with the camera and the motion of the ball through the simulation. FIG. 7 shows that the simulation result and the actual result are very similar to each other, And that the quantitative results of energy and energy are reasonable. In addition, we can see that the simulations are done correctly when we apply the various experimental conditions when we simulate, and we can see that the very important factor, the application of friction coefficient between ball and port, is very accurate.

FIG. 8 is a graph showing the milling efficiency of alumina balls, zirconia balls, and stainless steel balls according to the number of revolutions, and shows the result of calculating the power applied to the balls according to the rotation speed. According to FIG. 8, the higher the rotation speed of the ball, the more power is applied. On the other hand, in the case of the alumina ball having the lowest density, the higher the rotation speed, the higher the power than the zirconia ball, .

Fig. 9 shows the average ball kinetic energy according to the material of the ball at each rotation speed. According to FIG. 9, when the average kinetic energy of the alumina balls having the lowest density is 100 rpm, the average kinetic energy of the zirconia balls is higher than the average kinetic energy of the zirconia balls with time. When the number of revolutions is 300 rpm, Which is higher than the average kinetic energy of the ball of FIG.

Claims (9)

The mixed powder including the carbon nanotube (CNT) powder and the copper (Cu) powder was stirred ball milling at a rotation speed of 50 to 200 rpm for 12 hours or more to produce carbon nanotubes on the surface of the copper powder particles Wherein the carbon nanotube-coated copper nanoparticles are coated with the carbon nanotube-coated copper nanoparticles. The method according to claim 1,
And stirring ball milling is performed for 12 to 48 hours at a rotation speed of 50 to 100 rpm. The method according to claim 1,
Wherein the mixed powder comprises a carbon nanotube powder and a copper powder in a weight ratio of 0.5: 99.5 to 5: 95. The method according to claim 1,
Wherein the average particle size of the copper powder is 1 to 6 占 퐉. The method according to claim 1,
Characterized in that stirring ball milling is carried out using a ball made of alumina, zirconia or stainless steel. The method according to claim 1,
Wherein stirring ball milling is performed using a ball having a diameter of 2 to 10 mm. The method according to claim 1,
Wherein the weight ratio of the ball to the mixed powder is 15: 1 to 5: 1, and stirring ball milling is performed. The method according to claim 1,
Wherein stirring ball milling is performed at a ball filling ratio of 0.1 to 0.5. A copper particle coated with carbon nanotubes produced by the method according to any one of claims 1 to 8.

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