KR102530783B1 - Wet-dry hybrid method of preparing graphene flake metal composite and graphene flake metal composite composition prepared by the same - Google Patents

Abstract

The present invention relates to a method for preparing a graphene flake metal composite by preparing graphene flakes from graphite by a physical method and mixing a metal precursor powder with the graphene flake, and to a graphene flake metal composite prepared thereby. The method for preparing a graphene flake metal composite according to the present invention provides a graphene flake metal composite composition by mixing a metal precursor to obtain graphene flakes from graphite in a short time with a high yield and a simple process, and to improve electrical conductivity. can do. In addition, the graphene flake metal composite prepared through this is characterized by high purity and uniform particle characteristics, which are very excellent for industrial use.

Description

Manufacturing method of dry/wet graphene flake metal composite and graphene flake metal composite prepared thereby

The present invention relates to a method for preparing a graphene flake metal composite and a graphene flake metal composite prepared thereby.

Graphite is a material having a layered structure in which a plurality of layers are stacked. Each layer of graphite has a plate-like structure in which carbon atoms are connected in the form of a hexagon, and a plate-like single layer made of such carbon atoms is called graphene.

Graphene is a semi-metallic material that consists of a hexagonal honeycomb arrangement of carbon atoms by sp2 bonding in two dimensions and has a thickness of one atom. It is not only structurally and chemically very stable, but also has excellent mechanical properties. It has characteristics as an excellent conductor of electricity and heat, so it is in the limelight as a next-generation material such as energy, electronic material, and sensor material.

According to the production method, graphene is divided into a method of exfoliating graphene from a graphite crystal and a CVD method in which carbon is gasified at high temperature and deposited on a metal surface. The production methods mainly used in the industrial field are physical exfoliation method and chemical exfoliation method. , CVD method, epitaxial growth method, and the like.

The physical peeling method is a method of separating the tape after attaching it or peeling it off by applying a physical external force such as shear stress.

The chemical exfoliation method is a method of obtaining graphene through a reduction process after inducing exfoliation through the production of graphite oxide using a strong acid and an oxidizing agent.

In the CVD method, metals that are easily absorbed by carbon such as Ni, Cu, and Pt are deposited as a catalyst layer on a SiO2 substrate at high temperatures, and carbon reacts with the catalyst layer at a high temperature of 1,000 ° C or higher. It is a method of crystallizing on the surface to form graphene.

The epitaxial growth method is a method in which carbon, such as silicon carbide (SiC), is adsorbed into a crystal structure and heat-treated a material containing the material at a high temperature to evaporate silicon and form graphene from carbon in SiC along the crystal surface.

Among the above methods, the CVD method and the epitaxial growth method are produced in the form of graphene deposited on a substrate, and can obtain a graphene film of excellent quality, but can be used only for limited purposes such as electrodes or circuit boards, and the difficulty of the process The raw material used in manufacturing is expensive, and mass production is difficult, so the manufacturing cost is very high.

Therefore, in order to manufacture a graphene raw material that can be used for various purposes, a physical exfoliation method or a chemical exfoliation method is mainly used. However, the chemical exfoliation method is produced by oxidizing carbon using a chemical material to produce graphene oxide, and then reducing the graphene oxide again. During the process, impurities are included or oxygen in graphene oxide is not completely removed. The problem of poor pin purity appears. In addition, since it is manufactured by a chemical method, there is a disadvantage in that the yield is low and the unit price is high.

Among the physical peeling methods, the method using a tape is a method of obtaining graphene by dissolving the adhesive component in a solvent after repeating the tape attachment and peeling, and the quality is uneven and the manufacturing process or the industrial application of the produced product is low.

Regarding the method for producing graphene from graphite, Korean Patent Publication No. 10-2017-0103207 (Patent Document 1) first expands graphite in a mixture of sulfuric acid and nitric acid, followed by microwave or rapid heating. A method of secondarily expanding the expanded graphite by performing at least one of the processes (Rapid Thermal Annealing: RTA), dispersing the secondly expanded graphite by putting it in a separate solvent, and then applying ultrasonic waves to exfoliate, there is.

On the other hand, in Korea Patent Publication No. 10-2016-0114372 (Patent Document 2), molecules containing nitrogen or boron atoms are diffused between graphite layers, and then the expanded graphite is dispersed in a solvent and nitrogen-doped A method for obtaining graphene is presented.

However, in both Patent Documents 1 and 2, expanded graphite is dispersed in a solvent and then ultrasonic waves are applied to exfoliate the solvent. This method takes a long time, yield is low, and impurities other than carbon are sufficiently removed. Since it is not, there is a disadvantage that the purity is lowered.

In order to overcome the disadvantages of the prior art and widely utilize graphene in the industrial field, a paste composition that can be easily applied to devices in various industrial fields is prepared by preparing graphene flakes that are easy to mass-produce, have a high yield, and have a low cost. There is a need for technology for manufacturing.

Korean Patent Publication No. 10-2017-0103207 Korean Patent Publication No. 10-2016-0114372

The present invention overcomes the disadvantages of the prior art to manufacture a physically exfoliated graphene flake metal composite with high yield and easy mass production, and to manufacture an optimal graphene flake metal composite applicable to various industrial fields using the same. It is an object to provide a method and a graphene flake metal composite according to the method.

In order to achieve the above object, the present invention provides a method for manufacturing a graphene flake metal composite comprising the following steps.

Preparing expandable graphite (s1);

charging the expandable graphite into a furnace (s2);

sealing the furnace (s3);

heating the furnace by irradiating microwaves (s4);

maintaining or lowering the temperature of the expandable graphite by stopping the microwave irradiation (s5);

Repeating steps s4 to s5 until graphene flakes having a purity of 95% or more are obtained (s6);

preparing a mixed powder by mixing 100 parts by weight of the graphene flakes obtained in step s6 and 100 to 200 parts by weight of the metal precursor powder (s7);

A step (s8) of preparing a metal composite by sintering the mixed powder of step s7 is included.

In this case, the expandable graphite may be prepared by immersing in a volatile material containing one or two or more selected from the group consisting of an acid or a nitrogen compound.

In addition, the microwave may have a frequency band of 700 MHz to 2.5 GHz, more preferably may have a frequency band of 800 MHz to 1.2 GHz.

Graphene flakes according to the manufacturing method of the present invention are obtained by loading expandable graphite into a furnace and then processing it, wherein the furnace is a group consisting of alumina (Al2O3), zirconia (ZrO2), mullite, SiC and Si3N4 It may be made of one or two or more ceramic materials selected from, and may be preferably alumina (Al2O3).

The heating in step s4 may be performed after filling inert gas to maintain a predetermined pressure inside the furnace. At this time, it is preferably performed while maintaining the pressure inside the furnace at 1.2 to 10 bar, more preferably 1.2 to 5 bar. Most preferably, it may be 1.5 to 3 bar.

The step s5 is a step for stabilizing the graphene layer of the expandable graphite in an exfoliated state by heating, and after stopping the microwave irradiation, the temperature of the expandable graphite may be maintained or cooled as necessary. At this time, gas inside the furnace may be discharged to adjust the pressure inside the furnace and remove impurities. In addition, graphene and expandable graphite may be dispersed according to the particle size by rotating the furnace or using a stirrer installed inside the furnace.

Step s6 is to repeat steps s4 to s5, and the pressure inside the furnace may be performed while gradually increasing according to the number of repetitions, and may be repeated until graphene flakes having a purity of 95% or more are obtained.

In addition, in order to increase the efficiency of the entire manufacturing process and obtain graphene flakes of excellent quality, the pressure inside the furnace may be increased by 5 to 50% each time the step s6 is repeated. At this time, when the increase is less than 5%, there is no difference in pressure increase, and when the pressure is excessively increased to 50% or more, the graphene layer may not be peeled off well and rather agglomeration may occur.

In addition, the step s5 is a pretreatment step before heating by irradiating microwaves, and a process of spraying and incorporating the expandable graphite with an organic compound exfoliation enhancer may be further performed.

At this time, the peel enhancer may be a hydrocarbon having 6 to 8 carbon atoms, and more specifically, one or a mixture of two or more selected from the group consisting of hexane, heptane, cyclohexane, cycloheptane, and benzene. there is.

On the other hand, the amount of the exfoliation enhancer sprayed on the expandable graphite in step s5 may be gradually increased according to the number of repetitions.

The total process time can be further reduced by further including a step of pre-processing the expandable graphite by pulverizing it using a pulverizing equipment such as a milling machine before the step s2 of charging the furnace.

Meanwhile, a step of washing the graphene flakes prepared after the step s5 in an organic solvent and applying ultrasonic waves may be further included. In this case, ethanol may be used as the organic solvent.

The weight of the graphene flakes prepared according to the above manufacturing method is 90% by weight or more of the total weight of the initially introduced expanded graphite, and the manufacturing time is less than 3 hours while having a very high yield of 90% or more.

Unlike graphene flakes prepared by chemical methods such as oxidation-reduction, graphene flakes prepared by the manufacturing method of the present invention have almost no impurities and can have a high purity of 99% or more based on carbon components. .

The prepared graphene flake may have a thickness of 10 to 100 nm, more preferably 10 to 50 nm, and most preferably 10 to 20 nm.

In addition, the graphene flake may have a thickness distribution of 50 nm or less, more preferably 70 wt% or more, and most preferably 90 wt% or more of 50 nm or less, based on the total weight of the graphene flake. can have Meanwhile, the graphene flake may have a length ratio of a minor axis to a major axis of 1:1.1 to 2, more preferably 1:1.1 to 1.5, based on a plane perpendicular to the thickness direction.

In step s7, a graphene flake metal composite mixture powder is prepared by mixing the graphene flakes prepared in step s6 and the metal precursor powder. Preferably, it may be prepared by mixing 100 parts by weight of graphene flakes and 100 to 200 parts by weight of metal precursor powder.

In step s8, the graphene flake metal composite is prepared by sintering the graphene flake metal composite mixture powder.

Meanwhile, in the step s7, in the step of mixing the graphene flakes and the metal precursor mixed powder, a small amount of a metal coupling agent may be added to stir the reaction. The metal coupling agent is a metal oxide (C 60 H 123 O 15 P 3 Ti) nano coupling agent (Nano Coupling Agent) at a weight ratio of 100% to increase the affinity and reactivity between the graphene flake and the metal precursor powder interface From 0.3% to 0.6% by weight may be added.

A commercialization step of pulverizing and processing the sintered graphene flake metal composite into a product of any one of powder, sheet, film, and bar may be further included.

The method for producing a graphene flake metal composite according to the present invention has a simple process and can obtain graphene flakes from graphite in a short time with high yield. Graphene flakes applicable to various industrial devices using such graphene flakes It is possible to manufacture the metal composite composition at low cost. In addition, the prepared graphene flake metal composite composition has high purity of graphene and uniform particle characteristics, so it has excellent properties such as thermal conductivity and electrical conductivity, so it is suitable for industrial use.

1 is a SEM analysis picture of a graphene flake metal composite prepared by the manufacturing method of the present invention.
2 is a photograph of OM analysis of the graphene flake metal composite prepared by the manufacturing method of the present invention.
3 shows a comparison between the thermal conductivity of the graphene flake metal composite prepared by the manufacturing method of the present invention and the expandable graphite.

Since the present invention may have various changes and various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, it should be understood that this is not intended to limit the present invention to the specific disclosed form, and includes all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In this application, the terms "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Hereinafter, the present invention will be described in detail.

The present invention provides a method for preparing a graphene flake metal composite by manufacturing graphene flakes by a method of exfoliating from graphite by a physical method, and using the graphene flake metal composite.

As a method of physically exfoliating graphene, a Scotch tape exfoliation method is generally known. This method is a method of exfoliating a thin graphene layer from graphite by attaching scotch tape to graphite and then peeling it off. However, this method is difficult to mass-produce, and it is difficult to industrially use it because graphene of uniform quality cannot be obtained. As an industrially usable method, after temporarily expanding graphite by irradiating microwaves, a dry method of exfoliating the graphene layer using another mechanical method, impregnating graphite in a liquid phase such as an organic solvent, and then applying ultrasonic waves There is a wet method of exfoliating graphene by vibration.

However, the dry method has a disadvantage in that it only expands the graphite with microwaves to space apart the graphene layers, and requires an additional exfoliation process.

The wet method is a method of obtaining graphene dispersed in a solvent after gradually exfoliating the graphene layer by applying ultrasonic waves in a liquid phase such as an organic solvent.

The method for manufacturing a graphene flake metal composite according to the present invention is a dry/wet method that solves all the disadvantages of the above-mentioned dry method and wet method. By combining the advantages of, the process is simple, the yield and purity are high, and there is an advantage in that it can be manufactured quickly and at low cost. In particular, the efficiency of the process can be further increased without loss of material by maintaining the graphite in a wet state by adding an exfoliation enhancer during the process, if necessary.

Specifically, the manufacturing method of the graphene flake metal composite according to the present invention may include the following steps.

Preparing expandable graphite (s1);

charging the expandable graphite into a furnace (s2);

sealing the furnace (s3);

heating the furnace by irradiating microwaves (s4);

maintaining or lowering the temperature of the expandable graphite by stopping the microwave irradiation (s5);

Obtaining graphene flakes by repeating steps s3 to s5 until the carbon purity is 95% or more (s6);

preparing a mixed powder by mixing 100 parts by weight of the graphene flakes obtained in step s6 and 100 to 200 parts by weight of the metal precursor powder (s7);

A method of manufacturing a graphene flake metal composite including a step (s8) of preparing a metal composite by sintering the mixed powder of step s7.

First, expandable graphite is prepared as in step s1 above. Throughout the specification of the present invention, "expandable graphite" means graphite whose volume can be expanded by external factors. Graphite has a structure in which a plurality of plate-shaped single layers are stacked, and when heat or pressure is applied from the outside or other materials penetrate between the graphite layers, the gap between the layers widens and the volume expands. The expandable graphite used in the present invention may be prepared by immersing in one or more volatile materials selected from the group consisting of an acid or a nitrogen compound, and the volatile organic compound is inserted between the stacked layers of the expandable graphite. It can be.

The acid is one or two or more from the group consisting of sulfuric acid (H2SO4), nitric acid (HNO3), hydrochloric acid (HCl), hydrobromic acid (HBr), hydroiodic acid (HI) and perchloric acid (HClO4) may be selected, and preferably (H2SO4), hydrochloric acid (HCl), or a mixture thereof may be selected and used.

In addition, the nitrogen compound may be an organic solvent containing a nitrogen element such as N-methylpyrrolidone (NMP).

In the present invention, after the expandable graphite is loaded into the furnace and sealed as in steps s2 to s4 above. Heat treatment is performed by irradiating the furnace with microwaves from the outside. In this case, the microwave may have a frequency band of 700 MHz to 2.5 GHz.

The furnace may be made of one or more ceramic materials selected from the group consisting of alumina (Al2O3), zirconia (ZrO2), mullite, SiC and Si3N4, preferably alumina with excellent heat resistance and barrier properties. may be made up of

The microwave irradiation causes the molecules of the volatile organic compound in the sealed furnace to vibrate, thereby vaporizing as the temperature rises, and widening the gap between the stacked graphene monolayers of the expandable graphite. However, since the furnace is in a sealed state while the microwave is being irradiated, the pressure inside the furnace rises due to the evaporated gas, and when the inside of the furnace reaches a certain pressure, the stacked graphene layers of graphite gradually spread and rupture. As a result, graphene is exfoliated.

Therefore, in the heating of step s4, an inert gas may be additionally charged so that the inside of the furnace reaches and maintains a predetermined pressure. As the inert gas, helium, neon, krypton, xenon, argon, or radondaman may be selectively used, and a gas capable of reacting with carbon, such as nitrogen, is not preferable because it may greatly reduce the purity of graphene.

When the steps s4 to s5 are performed once, a portion of graphene may be exfoliated from carbon.

At this time, the pressure inside the furnace for exfoliating the expandable graphite into graphene may be preferably 1.2 to 10 bar, more preferably 1.2 to 5 bar, and most preferably 1.5 to 3 bar.

The step s6 is to repeat the process of exfoliating graphene by heating by irradiating microwaves, then stopping the heating to stabilize the material inside the furnace, and the pressure inside the furnace is gradually increased according to the number of repetitions. it could be As a result of the experiment, the optimal result was obtained by increasing the pressure by 5 to 20% according to the number of repetitions.

In addition, in the step s5, as a pretreatment step before heating by irradiating microwaves, a process of spraying and incorporating a peeling enhancer made of an organic compound into expandable graphite may be further performed. The expandable graphite can be maintained in a wet state by the exfoliation enhancer, and by being exposed to microwaves in a sealed furnace, the desirable effects of the dry method and the wet method among conventional physical exfoliation methods can appear at the same time.

At this time, the peel enhancer may be a hydrocarbon having 6 to 8 carbon atoms, and more specifically, one or a mixture of two or more selected from the group consisting of hexane, heptane, cyclohexane, cycloheptane, and benzene. there is.

On the other hand, the amount of the exfoliation enhancer sprayed on the expandable graphite in step s5 may be gradually increased according to the number of repetitions.

The total process time can be further reduced by further including a step of pre-processing the expandable graphite by pulverizing it using a pulverizing equipment such as a milling machine before the steps s2 to s4 of charging the furnace.

Meanwhile, a step of washing the graphene flakes prepared after step s6 in an organic solvent and applying ultrasonic waves may be further included. In this case, ethanol may be used as the organic solvent. According to the washing process, the impurity content of the graphene flake may be reduced and the purity thereof may be further increased.

The weight of the graphene flakes prepared according to the above manufacturing method is 90% by weight or more of the total weight of the initially introduced expanded graphite, and the manufacturing time is less than 3 hours while having a very high yield of 90% or more.

Unlike graphene flakes prepared by chemical methods such as oxidation-reduction, graphene flakes prepared by the manufacturing method of the present invention have almost no impurities and have a high purity of 99% or more based on carbon components.

The prepared graphene flake may have a thickness of 10 to 100 nm, more preferably 10 to 50 nm, and most preferably 10 to 20 nm.

In addition, the graphene flake may have a thickness distribution of 50 nm or less, more preferably 70 wt% or more, and most preferably 90 wt% or more of 50 nm or less, based on the total weight of the graphene flake. can have Meanwhile, the graphene flake may have a length ratio of a minor axis to a major axis of 1:1.1 to 2, more preferably 1:1.1 to 1.5, based on a plane perpendicular to the thickness direction.

In step s7, a metal precursor powder is mixed with the graphene flakes prepared by the manufacturing method as described above to make a mixed powder, and in step s8, the graphene flake metal composite according to the present invention is prepared by sintering the mixed powder.

In the mixing of the graphene flakes and the metal precursor powder, a mixed powder is prepared by mixing 100 parts by weight of the graphene flakes and 100 to 200 parts by weight of the metal precursor powder.

As the metal precursor powder, a metal precursor powder formed of a metal precursor powder containing at least one metal selected from the group consisting of tin, titanium, copper, gold, nickel, and magnesium may be used.

Example 1

Expandable graphite charging step: 20 g of expandable graphite immersed in sulfuric acid (H2SO4) was prepared, and the expandable graphite was charged into the center of the inner bottom of a cylindrical furnace with an open top.

The furnace was made of alumina material.

Furnace sealing step: A lid made of alumina was covered at the upper opening of the furnace and sealed using a sealing member to completely block the inflow and outflow of gas.

Microwave irradiation step: 1000 MHz microwave was irradiated to the furnace with an output of 700 W for 10 to 30 seconds. During microwave irradiation, the internal pressure of the furnace was maintained at 1.2 bar.

Step of stopping microwave irradiation: Heating by microwave irradiation was stopped, and the lid of the furnace was opened. Additionally, some of the gas inside the furnace was discharged.

The furnace sealing step, the microwave irradiation step, and the gas discharge step were additionally repeated twice under the same conditions.

According to the above process, 18 g of graphene flakes were obtained.

Example 2

It was performed in the same manner as in Example 1, but the internal pressure of the furnace was gradually increased each time the furnace was irradiated with microwaves to 1.2 bar during the first heating, 1.6 bar during the second heating, and 2.0 bar during the third heating.

According to the above process, 18 g of graphene flakes were obtained.

Example 3

It was performed in the same manner as in Example 1, but the internal pressure of the furnace was gradually increased each time the furnace was irradiated with microwaves, and maintained at 1.2 bar during the first irradiation, 1.6 bar during the second irradiation, and 2.0 bar during the third irradiation. . In addition, before the 2nd and 3rd microwave irradiation, a cyclohexane organic solvent was sprayed and wetted on the expanded graphite as a peel enhancer for pretreatment, and the amount of the peel enhancer sprayed was higher during the third irradiation than during the second microwave irradiation.

According to the above process, 18 g of graphene flakes were obtained.

Comparative Example 1

Expandable graphite charging step: 20 g of expandable graphite immersed in sulfuric acid (H2SO4) was prepared, and the expandable graphite was charged into the center of the inner bottom of a cylindrical furnace with an open top.

The furnace was made of alumina material.

Microwave irradiation step: 19 g of microwave-treated graphite was obtained after irradiating the furnace with 1000 MHz microwave at 700 W output for 60 seconds.

Comparative Example 2

Expandable graphite charging step: 20 g of expandable graphite immersed in sulfuric acid (H2SO4) was prepared, and the expandable graphite was charged into the center of the inner bottom of a cylindrical furnace with an open top.

The furnace was made of alumina material.

Furnace sealing step: A lid made of alumina was covered at the upper opening of the furnace and sealed using a sealing member to completely block the inflow and outflow of gas.

Microwave irradiation step: 19 g of microwave-treated graphite was obtained after irradiating the furnace with 1000 MHz microwave at 700 W output for 60 seconds.

Experimental Example 1

Characteristics of the graphene of Examples 1 to 3 and the microwave-treated graphite of Comparative Example 1 are compared and are shown in Table 1 below.

As a result of the experiment, in the case of Comparative Example 1, a significant level of graphene flakes were not formed, and in the case of Comparative Example 2, only a portion of the graphite was exfoliated into graphene flakes.

On the other hand, in the case of Examples 1 to 3, it was possible to obtain graphene flakes of high purity, and among them, in the case of Example 3, in which the pressure inside the furnace was gradually increased and pretreated with the exfoliation enhancer, the flakes having a thickness of 50 nm or less were 73% by weight was found to be of the highest quality.

From the above results, it can be seen that the exfoliation effect of the graphite, in which some graphenes are exfoliated, is further enhanced when irradiated with microwaves after pretreatment with an exfoliation promoter while gradually increasing the pressure, rather than irradiated with microwaves under the same conditions.

Experimental Example 2

The graphene flakes of Example 3 were dispersed in an ethanol solvent, washed with ultrasonic waves for 30 minutes, and then dried at 60° C. for 2 hours. The purity of the graphene flakes after drying was 99.6%.

From the above results, it can be seen that when the graphene flakes are prepared, dispersed in an ethanol solvent, and then ultrasonicated and washed, impurities partially remaining in the graphene flakes can be removed to achieve higher purity.

In the method for manufacturing a graphene flake metal composite according to the present invention, a graphene flake metal composite is prepared by mixing a metal precursor powder with a graphene flake prepared by the manufacturing method as described above to form a mixed powder, and sintering the mixed powder. . The mixing ratio is to prepare a mixed powder by mixing 100 parts by weight of the graphene flakes obtained in step s6 and 100 to 200 parts by weight of the metal precursor powder.

The metal precursor powder may be formed of a metal precursor powder containing at least one metal selected from the group consisting of tin, titanium, copper, gold, nickel, and magnesium.

As described above, a graphene flake metal composite may be prepared as a mixed powder by mixing the metal precursor powder with the dry/wet type graphene flake. In order to track the mixing ratio, analysis as shown in FIGS. 1 to 3 was performed.

As a result, it can be seen that the electrical conductivity varies depending on the ratio of the expandable graphite and the metal precursor.

Here, GSC-10: expandable graphite, metal precursor (1:10 ratio), GSC-30: expandable graphite, metal precursor (9:20 ratio), GSC-50: expandable graphite, metal precursor (1:1 ratio), GSC -100: Represents the expanded graphite synthetic sample (metal precursor content X).

According to the SEM analysis of FIG. 1 and the OM analysis of FIG. 2 , it can be seen that different states are displayed depending on the mixing ratio of the expandable graphite to the metal precursor. As shown in FIG. 2, the black part represents the dry and wet graphene flake, and the gray part of GSC_10 represents the metal composite. Referring to FIGS. 1 and 2 , it can be seen that as the ratio of the metal composite increases, the metal precursors between wet and dry graphene are irregularly attached.

Electrical conductivity varies depending on the content of the metal precursor, and as shown in the table of FIG. GSC-10: (expandable graphite, metal precursor (1:10 ratio), the highest content of metal precursor and relatively low electrical properties due to the small amount of expandable graphite. (In the case of electrical conductivity and resistance, the table in FIG. 3 Same as) GSC-30: expandable graphite, metal precursor (9: 20 ratio), GSC-50: expandable graphite, metal precursor (1: 1 ratio), the amount of expandable graphite and metal precursor are the same, the GSC Compared to -10 and GSC-30, it has the highest electrical conductivity and the lowest resistance among metal composites because of the large amount of expandable graphite with high conductivity GSC-100: Expandable graphite synthetic sample (metal precursor X), namely , is the wet and dry graphene flake itself prepared by high-energy irradiation in microave.

Therefore, referring to the above SEM analysis, OM analysis, and comparison of electrical conductivity and resistance according to the metal precursor content, the mixing ratio of the dry and wet graphene flakes and the metal precursor powder in step S7 is 100 weights of wet and dry graphene flakes It can be seen that a mixing ratio of 100 to 200 parts by weight of the metal precursor powder can obtain a suitable yield for electrical conductivity and resistance.

Meanwhile, in the step s7, in the step of mixing the graphene flakes and the metal precursor mixed powder, a small amount of a metal coupling agent may be added to stir the reaction. This is an optional method, and the metal coupling agent is a metal oxide (C 60 H 123 O 15 P 3 Ti) nano coupling agent to increase the affinity and reactivity between the graphene flake and the metal precursor powder interface. may be added in an amount of 0.3% to 0.6% by weight in a weight ratio of 100%.

In addition, in step s8, the graphene flake metal precursor mixture powder is sintered to prepare a graphene flake metal composite. The sintered graphene flake metal composite can be pulverized and commercialized into any one of a powder, sheet, film, or bar product.

Claims (9)

Preparing expandable graphite (s1);
charging the expandable graphite into a furnace (s2);
sealing the furnace (s3);
heating the expandable graphite by irradiating the furnace with microwaves (s4);
maintaining or lowering the temperature of the expandable graphite by stopping the microwave irradiation (s5);
Repeating steps s4 to s5 until graphene flakes having a purity of 95% by weight or more based on carbon components are obtained (s6);
preparing a mixed powder by mixing 100 parts by weight of the graphene flakes obtained in step s6 and 100 to 200 parts by weight of the metal precursor powder (s7); including,
Further comprising the step of pulverizing and pre-treating the expandable graphite using pulverization equipment before the steps s2 to s4,
The step s4 is performed by maintaining the pressure inside the furnace at 1.2 to 10 bar and additionally filling inert gas to reach and maintain the required pressure inside the furnace,
The step s5 is performed while gradually increasing the pressure inside the furnace according to the number of repetitions,
The step s7 is performed by adding a metal coupling agent of 0.3% to 0.6% by weight per 100% weight of the mixed powder of the graphene flake and the metal precursor powder.
Manufacturing method of graphene flake metal composite.
According to claim 1,
The expandable graphite is a method for producing a graphene flake metal composite prepared by immersing in a volatile material containing one or two or more selected from the group consisting of an acid or a nitrogen compound.
According to claim 1,
The furnace is a graphene flake metal composite made of one or more ceramic materials selected from the group consisting of alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), mullite, SiC and Si ₃ N ₄ Manufacturing method of.
According to claim 1,
The metal precursor powder is formed of a metal precursor powder containing at least one metal selected from the group consisting of tin, titanium, copper, gold, nickel, and magnesium. Method for producing a graphene flake metal composite.
delete delete According to claim 1,
In step s5,
A method for producing a graphene flake metal composite, further comprising the step of pre-treating expandable graphite by spraying an exfoliation enhancer composed of a hydrocarbon having 6 to 8 carbon atoms before irradiating microwaves.
A graphene flake metal composite prepared by the method of any one of claims 1 to 4 and 7.
According to claim 8,
The graphene flake metal composite is a graphene flake metal composite in which the purity of the graphene flake is 99% by weight or more.

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