WO2013162108A1 - Metal-carbon composite, preparation method thereof, and paste prepared using same - Google Patents

Description

Metal-Carbon Composites, Methods for Manufacturing the Same, and Pastes Prepared Using the Same

The present invention relates to a composite in which a metal and a carbon material are radially fused, and more particularly, a metal-carbon composite having an electromagnetic wave shielding capability and a method of manufacturing the same, in which a network between composites is formed while the carbon material is radially grown on a metal particle surface. And it relates to a paste prepared using the same.

Recently, as IT devices such as e-books, mobile phones, flat-panel TVs and digital cameras are gradually thinned and integrated, electromagnetic wave shielding capability is becoming important. Since electromagnetic waves not only affect the human body but also cause fatal errors in various electronic devices, development of materials for shielding harmful electromagnetic waves has been actively conducted worldwide.

On the other hand, the most advantageous material for shielding electromagnetic waves is a metal material, when molding the IT and electronic materials using only this, it is difficult to form a beautiful curved surface or complex shape of the IT equipment by a process such as die casting, Due to the heavy characteristics, there is a problem in weight reduction. Therefore, in order to improve the electromagnetic shielding ability of IT devices, studies are conducted to expect the electromagnetic shielding effect by uniformly dispersing materials such as carbon fiber, carbon black, carbon fiber, and metal powder in the polymer, but the effect is insufficient. The amount of material to be added must be increased. In this case, however, not only an increase in the unit cost but also a limitation of the process due to the increase in the viscosity occurs.

In another method, research has been conducted by large corporations and research institutes to improve the electromagnetic shielding ability by increasing the conductivity of materials by directly hybridizing carbon nanomaterials such as metal and carbon nanotubes uniformly in polymer bases. Due to the inherent van der Waals forces of the nanotubes, aggregation occurs easily, resulting in poor dispersibility. In addition, it was pointed out that the carbon nanotubes are arranged in the injection direction during the injection molding, so that the network is not formed properly, and the reliable connection between the metal and the carbon nanotubes is not guaranteed, and thus the lack of conductivity is indicated.

According to the present invention, when the metal and the carbon material are bonded, the carbon material is directly grown on the metal surface to improve the bonding force, thereby preventing short circuit between the metal particles and the carbon material, and being entangled in a network form while the carbon material is radially formed on the metal surface. It is to provide a metal-carbon composite with improved electrical conductivity, a method of manufacturing the same, and a paste prepared using the same.

The technical problems to be achieved by the present invention are not limited to the technical problems mentioned above.

Metal-carbon composite of the present invention for realizing the above object comprises a plurality of metal particles, and a carbon material formed directly attached radially to the surface of the metal particles, the metal particles and carbon by the carbon material The materials can be entangled with each other to form a network.

Specifically, a carbon coating layer may be further formed on the surface of the metal particles.

The carbon material may be a straight linear carbon nanofilament (CNF) having a diameter of 5 nm to 500 nm or a carbon coil (CC) having a spiral protrusion having a diameter of 100 nm to 500 μm.

The metal particles may have a size of 10 nm or more and less than 500 μm.

Method for producing a metal-carbon composite of the present invention for realizing the above object, generating a metal particle, placing the metal particle on the substrate of the reaction chamber, and the carbon material on the surface of the metal particle radially Direct growth.

Specifically, the carbon material may be at least one of carbon nanotubes (CNT), carbon nanofilaments (CNF), and carbon coils (CC).

In the generating of the metal particles, the metal particles may be generated by an electroexplosion method.

The generating of the metal particles may further include coating carbon on the surface of the metal particles at the same time as the generation of the metal particles.

The growing may further include forming the network part by being entangled between the metal particles and the carbon materials while the carbon material is growing.

In the growing step, the carbon material may be grown on the surface of the metal particles for at least 5 minutes at a temperature of 700 to 900 ° C. and a pressure of 50 to 250 torr.

In the growing step, plasma is maintained while maintaining the inside of the reaction chamber in a reactive gas atmosphere to grow a carbon material on the surface of the metal particles, and the reactive gas is a hydrocarbon gas (C _x H _y GAS) and hydrogen (H). ₂ ) may be a mixed gas, or a mixed gas of hydrocarbon gas (C _x H _y GAS), hydrogen (H ₂ ), and hydrogen sulfide (H ₂ S) or sulfur hexafluoride (SF ₆ ) gas. .

The paste may be prepared using the metal-carbon composite prepared by the method of any one of the above.

According to the metal-carbon composite and the manufacturing method described above, the carbon material is directly grown on the metal surface to improve the bonding force, thereby preventing short circuit between the metal particles and the carbon material, and forming the carbon material radially on the metal surface to form a network. It is entangled with, which improves the electrical conductivity and enhances the electromagnetic shielding effect.

In addition, when the metal-carbon composite is used to disperse in a polymer base, paste or metal ink, it is possible to reduce the weight, cost, and formability of electronic devices, and to produce high-frequency electronic components, next-generation information communication devices, and robots. It can be used as a beautiful and precise core parts material.

1 is a view showing a metal-carbon composite of the present invention.

2 is a scanning electron microscope (SEM) photograph of one embodiment of the present invention.

3 is a scanning electron microscope (SEM) photograph of low and high magnification of another embodiment of the present invention.

4 is a graph illustrating Raman spectroscopic spectral patterns of carbon coils according to another embodiment of the present invention.

5 is a flowchart illustrating a method of manufacturing a metal-carbon composite of the present invention in order.

6 is a TEM (transmission electron microscope) photograph of a metal powder serving as a seed (seed) associated with the present invention.

7 is a high-resolution TEM (transmission electron microscope) photograph of FIG. 6 to show a carbon coating of the metal powder according to the present invention.

8 is an x-ray diffraction analysis graph of another embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention. Like elements in the figures are denoted by the same reference numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

1 is a view showing a metal-carbon composite of the present invention.

Referring to this figure, the metal-carbon composite consists of a plurality of metal particles and a carbon material.

The metal particles act as seeds for forming the metal-carbon composite of the present invention, and are in the form of powder in which a plurality of metal particles are collected. Specifically, such metal particles are in the form of metal powders having a size of 10 nm or more and less than 500 μm. When the size of the metal particles is less than 10 nm, the diameter of the metal particles is very small, it may be difficult to grow a carbon material on the surface. In addition, when the size of the metal particles is 500 μm or more, the size of the metal particles is excessively large, the electrical conductivity improvement effect is reduced, or it may be difficult to manufacture a product of a beautiful design with a material containing the composite of the present invention.

In addition, a carbon coating layer may be further formed on the surface of the metal particles. When the carbon coating layer is formed, the carbon material is more effectively fixed and grown on the surface of the metal particles, thereby preventing an electrical short circuit between the metal particles and the carbon material.

On the other hand, the carbon material is directly attached radially formed on the surface of the metal particles. In particular, in the present invention, as the carbon material is simultaneously grown on the surfaces of the plurality of metal particles, the metal particles and the carbon material are entangled with each other to form a network. These networks are connected to each other to greatly improve the electrical conductivity and increase the electromagnetic shielding effect. Here, the carbon material includes both carbon nanofilament (CNF; FIG. 2) or carbon coil (CC; FIG. 3), as shown in FIGS. 2 and 3.

Specifically, carbon nanofilament (CNF) may be formed on the surfaces of the plurality of metal particles. In particular, as an embodiment of the present invention, as shown in Figure 2, it is preferably formed of a straight linear carbon nanofilament (CNF) having a diameter of 5nm to 500nm. In this case, when the diameter of the carbon nanofilament (CNF) is less than 5nm, the thickness may be too thin, which may cause a problem that the carbon nanofilament (CNF) is broken when the product is manufactured, and the diameter of the carbon nanofilament (CNF) is If the thickness is greater than 500 nm, it may be difficult to manufacture a product having a beautiful design when manufacturing the product using the thickness thereof.

In general, carbon nanofilament (CNF) refers to carbon nanotubes (CNT) and carbon nanofibers generically. Carbon nanotubes are formed to have empty spaces in the process of forming carbon nanomaterials, and carbon nanofibers are formed in a stacked structure without empty spaces inside the carbon nanotubes.

The carbon nanofilament is mainly formed in a linear structure and mixed with the polymer materials to produce a product, wherein the carbon nanofilaments are separated from the polymer materials without being uniformly mixed well with the polymer materials. do. This phenomenon can occur in all processes of mixing the carbon nanofilament with the polymer material to produce a composite, it is important to disperse the carbon nanofilament in the polymer material. Therefore, by directly attaching carbon nanofilaments to the surface of the metal particles according to the present invention, the phenomenon in which the polymer material and the carbon nanofilaments are sequestered can be solved at the source.

On the other hand, when a current flows through the wire, a magnetic field is generated in the vertical direction. The magnetic field in the vertical direction is also generated in the carbon nanofilament (CNF) or carbon nanotube (CNT) grown in one embodiment of the present invention.

Therefore, as another embodiment of the present invention, as shown in FIG. 3, when the carbon coil is applied, the electromagnetic shielding efficiency is improved because electricity generates a magnetic field in all directions while rotating along the coil shape. In addition, the carbon coil (hereinafter referred to as carbon coil; CC) is excellent in the elastic restoring force has the advantage that is restored to its original shape even if a large deformation occurs.

As such, when the metal particles and the carbon coil are formed into a composite and dispersed in the polymer, the coils can be deformed in various directions due to the characteristics of the coil, and easily form a network in the polymer, thereby improving the conductivity and shielding electromagnetic waves. Performance is improved.

Specifically, the carbon coil formed on the surface of the metal particles according to the present invention is in the form of a spiral projection having a diameter of 100nm to 500㎛. As the carbon coil is formed while the carbon nanofilament formed with the diameter of nano or micro forms a spiral protrusion, a hollow part is inevitably formed, and thus, it is difficult to form the carbon coil with a diameter of less than 100 nm. In addition, when the diameter of the carbon coil is formed to more than 500㎛, the diameter of the carbon material is excessively thick, it may be difficult to produce a product of a beautiful design when manufacturing the product using this.

Looking at the Raman spectroscopy spectrum of the carbon coil formed on the surface of the metal particles, it shows a typical pattern corresponding to the carbon coil as shown in Figure 4, thereby confirming that the carbon coil was well formed on the surface of the metal particles by the present invention. , Figure 4 shows the spectral pattern of graphite (graphite) and graphene (graphene) together to compare and confirm the Raman spectroscopic spectral pattern results of the carbon coil.

In the metal-carbon composite of the present invention, as shown in the flowchart of FIG. 5, the step of generating metal particles (S10), placing the metal particles on a substrate of the reaction chamber (S20), and carbon on the surface of the metal particles It is prepared including the step of growing a material (S30).

First, metal particles or carbon-coated metal particles serving as seeds for generating a metal-carbon composite are produced.

The metal particles are in the form of a powder in which a plurality of metal particles are collected, and the metal particles are characterized by having a size of 10 nm or more and less than 500 μm. When the size of the metal particles is less than 10 nm, the diameter of the metal particles may be very small, it is difficult to grow a carbon material on the surface. In addition, when the size of the metal particles is 500 μm or more, the size of the metal particles is excessively large, so that the effect of improving electric conductivity may be reduced, or it may be difficult to produce a beautiful design with a material including the material of the present invention.

Alternatively, carbon may be coated on the surface of the metal particles simultaneously with the generation of the metal particles. Specifically, the carbon-coated metal particles are formed by coating a carbon layer having a thickness of 3 nm to 20 nm on the surface of the particles, thereby serving to allow the carbon material to grow well from the surface carbon layer. Carbon-coated metal particles are also preferably formed in the range of 10 nm or more and less than 500 µm, which is the size of the metal particles described above.

As an example, the metal particles or metal particles coated with carbon may be generated by an electroexplosive method, and the particle shape and distribution of the carbon coated metal particles generated by the electroexplosive method may be confirmed in the photograph of FIG. 6, and FIG. 7. In the photo, you can see the appearance of carbon coated on the surface of the metal particles.

In the electroexplosion method, a metal wire is placed inside an electroexplosion chamber and a high voltage and a high current are applied in a pulse form within several to several tens of microseconds to sublimate the metal wire, and then metal vapor is condensed to form a metal powder. This is how you do it. The metal wires here include copper, nickel, aluminum, iron, gold or silver metals alone, alloys thereof or mixtures thereof. In addition, the metal wire used in the electric explosion is characterized by having a diameter of 1mm or less. This is because, when the diameter of the metal wire is larger than 1 mm, the yield of metal powder due to electric explosion may be low, or an excessive voltage may be required to explode the metal wire.

When the electroexplosion method is implemented, a voltage of a predetermined magnitude is repeatedly applied to the metal wire in the chamber at a predetermined cycle. Specifically, an electric explosion method is performed by applying a voltage of 10 to 40 kV at a period of 0.5 seconds to 10 seconds. Here, if the voltage is applied in a size of less than 10kV or at intervals of 10 seconds or more, the strength of the voltage may be weak, so that the metal wire may not be formed in the form of metal powder. Under the influence of the applied voltage, the metal wire may explode and cause excessive device damage or safety accidents.

The production method of the metal particles is not limited to the practice of the invention, it is also possible to produce the metal particles by a method such as spray pyrolysis, flame method, high-frequency plasma.

Thereafter, the metal particles are placed on the substrate of the reaction chamber. (S20) Here, the reaction chamber is a chamber for growing a carbon material on the surface of the metal particles. The substrate of the ceramic material may be provided inside the reaction chamber. Specifically, the substrate may be in the form of a ceramic boat. That is, the metal particles are placed in the ceramic boat and placed inside the reaction chamber.

After placing the metal particles in the reaction chamber, the carbon material is grown directly on the surface of the metal particles, as shown in the photographs of FIGS. 2 and 3 (S30). Here, the carbon material is carbon nanotubes (CNT) or carbon. It may be at least one of nanofilament (CNF), carbon coil (CC).

Specifically, the carbon material on the surface of the metal particles may be grown by thermal CVD for at least 5 minutes at a temperature of 700 to 900 ° C. and a pressure of 50 to 250 torr. At this time, when the temperature is less than 700 ℃, the pressure is less than 50 torr, or the growth time is less than 5 minutes, the carbon material is not grown on the surface of the metal particles or the degree of growth may be very insignificant. In addition, when the temperature is more than 900 ℃ or the pressure is more than 250 torr, there may be a problem that the diameter of the carbon material is excessively thick on the surface of the metal particles.

In addition, when thermal CVD is performed for the present invention, the carbon material is grown on the surface of the metal particles while maintaining the inside of the reaction chamber in a reactive gas atmosphere.

The reactive gas may be a mixed gas in which hydrocarbon gas (C _x H _y GAS) and hydrogen (H ₂ ) are mixed, wherein the carbon material formed is carbon nanotube (CNT) or carbon nanofilament (CNF). Here, acetylene (C ₂ H ₂ ) may be used as an embodiment of the hydrocarbon gas (C _x H _y GAS).

Alternatively, an inert gas may be added to the mixed gas in which the aforementioned hydrocarbon gas (C _x H _y GAS) and hydrogen (H ₂ ) are mixed as the reactive gas. Specifically, it is preferable to use a mixed gas containing a mixture of hydrocarbon gas (C _x H _y GAS), hydrogen (H ₂ ), and hydrogen sulfide (H ₂ S) or sulfur hexafluoride (SF ₆ ) gas as a reactive gas. It is desirable to grow the material effectively. In this case, the formed carbon material includes the form of carbon coil (CC), and FIG. 8 shows X corresponding to metal particles Ni and carbon coil (CC) as X-ray diffraction analysis results of the metal-carbon composite thus formed. Can be.

Alternatively, it is possible to form various types of carbon materials by changing the above reaction conditions (temperature, pressure, time, reactive gas, etc.), and according to the reaction conditions, carbon nanotubes (CNT), carbon nanofilaments (CNF), And it is also possible to form in the form of a mixture of two carbon materials of the carbon coil (CC).

In the above-described method, the carbon material is grown to be fixed-bonded directly on the surface of the metal particles or the carbon coated metal particles, wherein the carbon material is grown radially. The carbon material is radially grown and entangled between the metal particles and the carbon material to form a three-dimensional network, thereby increasing electrical conductivity.

In addition, the paste may be prepared using the metal-carbon composite prepared in this manner. That is, the metal-carbon composite is dispersed in the matrix, the central metal particles act as electromagnetic shielding, and the three-dimensional network made of carbon material increases electrical conductivity, thereby improving electromagnetic shielding ability.

According to the metal-carbon composite and the manufacturing method described above, the carbon material is directly grown on the metal surface to improve the bonding force, thereby preventing short circuit between the metal particles and the carbon material, and forming a carbon material radially on the metal surface to form a network. It can be formed to improve the electrical conductivity and increase the electromagnetic shielding effect.

In addition, when the metal-carbon composite is used to disperse in a polymer base, paste, or apply to metal ink, it is possible to reduce the weight, cost, and formability of electronic devices, and to produce high-frequency electronic components, next-generation information communication devices, and robots. It can be used as a beautiful and precise core parts material.

Such a metal-carbon composite, a method of manufacturing the same, and a paste prepared using the same are not limited to the configuration and operation of the embodiments described above. The above embodiments may be configured such that various modifications may be made by selectively combining all or part of the embodiments.

<Description of the code>

100: metal-carbon composite 110: metal particles

111: carbon coating layer 130: carbon material

150: network

Claims (12)

A plurality of metal particles; And Includes; carbon material directly attached to the surface of the metal particles radially; The metal-carbon composite is composed of the metal particles and the carbon material entangled with each other by the carbon material in a network form. The method according to claim 1, Metal-carbon composite is a carbon coating layer is further formed on the surface of the metal particles. The method according to claim 1, The carbon material is a metal-carbon composite having a straight linear carbon nanofilament (CNF) having a diameter of 5 nm to 500 nm or a carbon coil (CC) having a spiral protrusion having a diameter of 100 nm to 500 µm. The method according to claim 1, The metal particle is a metal-carbon composite of 10 nm or more and less than 500 ㎛ size. Producing metal particles; Positioning the metal particles on a substrate of the reaction chamber; And Method for producing a metal-carbon composite comprising a; directly growing a carbon material radially on the surface of the metal particles. The method according to claim 5, The carbon material is at least one of carbon nanotubes (CNT), carbon nanofilaments (CNF), carbon coils (CC) manufacturing method of a metal-carbon composite. The method according to claim 5, Generating the metal particles, Method of producing a metal-carbon composite to produce the metal particles by an electroexplosion method. The method according to claim 5, Generating the metal particles, Simultaneously with the generation of the metal particles, coating the carbon on the surface of the metal particles; manufacturing method of a metal-carbon composite further comprising. The method according to claim 5, The growing step, As the carbon material grows, entangled between the metal particles and the carbon material to form a network. The method of manufacturing a metal-carbon composite further comprising. The method according to claim 5, The growing step, Method for producing a metal-carbon composite to grow the carbon material on the surface of the metal particles for at least 5 minutes at a temperature of 700 to 900 ℃, pressure of 50 to 250 torr. The method according to claim 5, The growing step, Plasma is formed while maintaining the inside of the reaction chamber in a reactive gas atmosphere to grow a carbon material on the surface of the metal particles, The reactive gas is a mixed gas in which hydrocarbon gas (C _x H _y GAS) and hydrogen (H ₂ ) are mixed, or hydrocarbon gas (C _x H _y GAS), hydrogen (H ₂ ), and hydrogen sulfide (H ₂ S) or A method for producing a metal-carbon composite, which is a mixed gas in which sulfur hexafluoride (SF ₆ ) gas is mixed. A paste prepared using a metal-carbon composite prepared by the method of claim 5.

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