KR101656131B1 - Method of Manufacturing Nano Material from Graphite-Metal Composite by Mechanical Alloying and Collected Nano Material Using the Same - Google Patents

Abstract

TECHNICAL FIELD The present invention relates to a nanocomposite material capable of significantly improving heat dissipation performance by mechanically alloying a graphite-metal composite material, and a nanocomposite material produced by the method. A method of manufacturing a nanocomposite material using mechanical alloying of a graphite-metal composite material according to an exemplary embodiment of the present invention comprises mechanically alloying (mechanical alloying) an Al powder and an expanded graphite powder for 2 hours using a ball mill A first step of mixing the Al powder and the expanded graphite powder and a second step of performing mechanical alloying for the mixed Al powder and the expanded graphite powder for 20 minutes to 30 minutes, The two-step mechanical alloying is a high energy ball mill process.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a nanocomposite material by mechanical alloying of a graphite-metal composite material, and a nanocomposite material by the method of manufacturing the nanocomposite material.

TECHNICAL FIELD The present invention relates to a nanocomposite material capable of significantly improving heat dissipation performance by mechanically alloying a graphite-metal composite material, and a nanocomposite material produced by the method.

A light emitting diode (LED) is a semiconductor device that can emit light of various colors by forming a light emitting source through a PN junction of a compound semiconductor (compound semiconductor).

Such an LED has a long lifetime, can be reduced in size and weight, has a strong directivity of light, and can be driven at a low voltage. Further, the LED is resistant to impact and vibration, does not require preheating time and complicated driving, can be packaged in various forms, and can be applied to various applications. Therefore, in recent years, attempts have been made to replace conventional lighting lamps such as incandescent lamps, fluorescent lamps, and halogen lamps with LEDs.

On the other hand, as the electronics industry develops, devices become smaller and portable electronic products become thinner. Therefore, the method of controlling the heat becomes a very important problem.

Carbon nanotubes (CNTs) and graphenes can be used as new heat sinks in mobile phones, digital audio and personal digital devices, according to a number of recent publications. Therefore, it is considered that the problem of malfunction due to overheating can be solved through the results of these studies.

In addition, an amplifier used in a cellular phone base station for transmitting wireless communication information is also required to have a high frequency and a high output. Since the heat output of such a high output transistor is very large, the heat dissipation function is very important.

 The inside of the chip has a heat dissipation device, which can release heat when a lot of heat is generated. Currently, the heat dissipation device mainly uses a material such as copper or aluminum. In addition, the cooling speed can be improved through the flow of a small fan or fluid, but there are limitations in reducing the volume. Particularly, in the case of a high output amplifier, in order to discharge a large amount of heat generated in a high output transistor, Has been pointed out to be insufficient.

Among the heat dissipation devices developed in the past, in particular, the heat dissipation products using the graphite / resin have a lower performance than the conventional aluminum die castings. There is a problem in that a method of using carbon (CNT, activated carbon, graphite, etc.) mixed with resin which is attempted in domestic is expensive and the resin ratio is high and the heat radiation characteristic is low.

Further, in order to increase the thermal conductivity of such a resin composite, a large amount of filler (carbon type) is filled. Such filling increases the viscosity, resulting in deterioration of moldability and further difficulty in producing a product by injection molding or the like , The strength of the final product is also unsatisfactory.

Therefore, there is a growing demand for flexible materials with high thermal conductivity, small size and thinness, and research and development of high performance heat-resistant materials, which rely on imports of more than 80%, are required.

Korean Patent No. 10-1193991 Korean Patent No. 10-1310162

Disclosure of Invention Technical Problem [8] The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a method of manufacturing a nanocomposite material by mechanically alloying a graphite- Its purpose is to provide users with composite materials.

In addition, the present invention provides a nanocomposite material manufacturing method and a nanocomposite material manufacturing method which can give various heat-dissipating products differentiated to LED, electronic equipment, small electronic products and the like by increasing and stabilizing the product density It has its purpose.

In addition, the present invention is excellent in low heat resistance, weight reduction, cost reduction, environment friendliness and corrosion resistance, and contributes to the heat dissipation market of household appliances due to its high competitiveness. The present invention aims to provide a nanocomposite material manufacturing method and a nanocomposite material manufacturing method which can greatly contribute to the development of the local industry.

Another object of the present invention is to provide a nanocomposite material manufacturing method and a nanocomposite material manufacturing method which can be cost-competitive by replacing the heat radiation product of the present invention.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are not intended to limit the invention to the precise form disclosed. It can be understood.

A method for manufacturing a nanocomposite material using mechanical alloying of a graphite-metal composite material according to an example of the present invention for realizing the above-described problems is a method for manufacturing a nanocomposite material by using a ball mill for 2 hours for an Al powder and an expanded graphite powder A first step of performing mechanical alloying to mix the Al powder and the expanded graphite powder and a second step of performing mechanical alloying for the mixed Al powder and expanded graphite powder for 20 to 30 minutes And the second stage of the mechanical alloying is a high energy ball mill process.

In the second step, the powder subjected to the mechanical alloying is compressed by a cold press to produce a predetermined compact, and a fourth step of sintering the compact at a predetermined sintering temperature for 2 hours or 4 hours .

In the third step, the molded body may be manufactured by charging the powder into a mold at a predetermined pressure and compressing the molded body.

Further, in the sintering process of the fourth step, it is possible to control so that no other compound phase is generated in the formed body.

In addition, the sintering temperature may be a temperature between 300 ° C and 400 ° C.

Also, the ratio of the Al powder and the expanded graphite powder mixed in the first step may be 9: 1.

Also, the second time may be a time between 20 minutes and 30 minutes.

Meanwhile, a nanocomposite material related to an example of the present invention for realizing the above-mentioned problems can be manufactured by using one of the methods of manufacturing a nanocomposite material using mechanical alloying of the graphite-metal composite material.

Disclosure of Invention Technical Problem [8] The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a method of manufacturing a nanocomposite material by mechanically alloying a graphite- Composite material can be provided to the user.

Further, the present invention can provide a nanocomposite material by a manufacturing method of a nanocomposite material capable of giving various heat-dissipating products differentiated to an LED, an electronic device, a small electronic product, and the like by raising and stabilizing a product density and a manufacturing method thereof have.

In addition, the present invention is excellent in low heat resistance, weight reduction, cost reduction, environment friendliness and corrosion resistance, and contributes to the heat dissipation market of household appliances due to its high competitiveness. A nanocomposite material can be provided to the user by a manufacturing method of the nanocomposite material and a manufacturing method thereof which can contribute greatly to the development of the local industry.

In addition, it is possible to provide a nanocomposite material by a manufacturing method of a nanocomposite material and a nanocomposite material manufactured by the manufacturing method, which can be replaced with the heat-radiating article of the present invention and cost reduction is anticipated and price competitiveness can be ensured.

It should be understood, however, that the effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those skilled in the art to which the present invention belongs It will be possible.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate a preferred embodiment of the invention and, together with the description, serve to provide a further understanding of the technical idea of the invention, It should not be construed as limited.
FIG. 1 is a flowchart showing an example of a method for producing a nanocomposite material by using the mechanical alloying of the graphite-metal composite material of the present invention.
FIGS. 2A to 2F are photographs of an Al powder and an expanded graphite powder subjected to mechanical alloying according to the present invention, which were observed using an FE-SEM.
FIGS. 3A and 3B show photographs of an Al powder and an expanded graphite powder subjected to mechanical alloying in a high-energy ball mill for 10 minutes using an FE-SEM.
Fig. 4 shows X-ray diffraction patterns measured on Al-powder and expanded graphite powder subjected to mechanical alloying.
5 shows a pattern of a wavelength analysis spectroscopic analyzer measured for an Al powder and an expanded graphite powder subjected to mechanical alloying.
Fig. 6 shows an X-ray diffraction pattern measured after sintering of an Al-powder and an expanded graphite powder subjected to mechanical alloying.
Fig. 7 shows the thermal conductivity measured after sintering of the Al alloy powder and the expanded graphite powder subjected to the mechanical alloying.
8A and 8B show an example of a nanocomposite material using mechanical alloying of the graphite-metal composite material of the present invention.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. In addition, the embodiment described below does not unduly limit the contents of the present invention described in the claims, and the entire configuration described in this embodiment is not necessarily essential as the solution means of the present invention.

Although graphite has better electrical conductivity than aluminum, most of the products using resin are not developed beyond the limits of conventional graphite. Since the resin for forming the product of graphite is a factor that hinders the heat radiation performance, the performance is remarkably lower than that of aluminum.

The present invention is to develop a new method of expanding graphite / metal (Al, Cu, Mg, etc.) composite and to increase and stabilize the product density to develop various different heat dissipation products such as LED, electronic devices and small electronic devices I would like to propose.

Hereinafter, a method for producing a nanocomposite material using mechanical alloying of a graphite-metal composite material and a nanocomposite material for the method will be described in detail with reference to the drawings.

FIG. 1 is a flowchart showing an example of a method for producing a nanocomposite material by using the mechanical alloying of the graphite-metal composite material of the present invention.

Referring to FIG. 1, mechanical alloying (MA) is performed on an Al powder and an expanded graphite powder for about 2 hours (first time) using a general ball mill, and the Al powder and the expanded graphite powder The powder is mixed (S10).

Specifically, the present invention utilizes the produced expanded graphite, and graphite used refers to graphite, expanded graphite, oxidized graphite and its expansion, and graphite includes both natural graphite and artificial graphite.

Expanded graphite refers to graphite which has been deposited in sulfuric acid, nitric acid, and mixtures thereof and then expanded at a temperature of from 400 占 폚 to 1000 占 폚. Oxidized graphite is a technology for producing compositions and molded articles containing graphite which is oxidized by adding an oxidizing agent when it is immersed in an acid solution and graphite in which oxidized graphite is expanded at high temperature. Such a manufacturing technique has already been established and used as the graphite material of the present invention.

Al powder (99.9%, -200 mesh) and expanded graphite powder were mixed in weight ratio (weight%, wt%) at a ratio of 9: 1 and mixed for 2 hours in a normal ball mill for even distribution.

Next, the mixed Al powder and the expanded graphite powder are subjected to mechanical alloying for a second time (S20). The mechanical alloying in step S20 is a high energy ball mill process, and the second time is between 10 minutes and 30 minutes, and preferably between 20 minutes and 30 minutes.

Specifically, mechanical alloying was performed in a high energy ball mill from 10 minutes to a maximum of 30 minutes. After the mechanical alloying, the shape of the powder was observed using a field emission scanning electron microscope (FE-SEM) in order to observe the shape of the powder, and as a result, a photograph as shown in FIGS. 2A to 2F was obtained.

FIGS. 2A to 2F are photographs of an Al powder and an expanded graphite powder subjected to mechanical alloying according to the present invention, which were observed using an FE-SEM. Fig. 2 (a) is a photograph of Al powder and expanded graphite powder observed by mechanical alloying using a general ball mill, and Figs. 2 (b) to 2 (f) Mechanical alloying is performed to show the photographs observed. The FE-SEM photographs of Figs. 2A to 2F were observed at magnification x 500.

As shown in FIGS. 2A to 2F, it can be seen that the Al powder and the expanded graphite powder are uniformly distributed in the case of the first mixed powder, and the finer powder progresses as the mechanical alloying time increases have.

FIGS. 3A and 3B are photographs of Al powder and expanded graphite powder subjected to mechanical alloying in a high-energy ball mill for 10 minutes using FE-SEM, respectively, which were observed at × 3000 and × 50000, respectively.

As shown in FIGS. 3A and 3B, the agglomeration phenomenon of the powder was observed when 30 minutes of mechanical alloying was observed. As a result of observation at a high magnification, 5-10 nanometers (nano meter, nm) Is observed.

Fig. 4 shows X-ray diffraction patterns measured on Al-powder and expanded graphite powder subjected to mechanical alloying. 4 (a) is a result of mechanical alloying using a general ball mill, and FIGS. 4 (b) to 4 (f) show mechanical alloying for 10 minutes, 15 minutes, 20 minutes, 25 minutes, to be.

X-ray diffraction (XRD) test was performed to observe the degree of phase change at the time of high-energy mechanical alloying by mixing Al powder and 10 wt% expanded graphite powder.

As shown in Fig. 4, it can be seen that the peak of the expanding graphite disappears from the specimen subjected to mechanical alloying for 15 minutes. It is believed that the mechanical alloying process resulted in the powder synthesis, and when the mechanical alloying was performed for more than 20 minutes, the peaks of the expanded graphite completely disappeared. However, additional experiments should be conducted to confirm the phase transformation of the extinction peak.

5 shows a pattern of a wavelength analysis spectroscopic analyzer measured for an Al powder and an expanded graphite powder subjected to mechanical alloying.

Wavelength Dispersive Spectroscopy (WDS) analysis was conducted to confirm whether the disappearance of the expanded graphite peak was oxidized by oxygen bonding as the mechanical alloying increased.

As shown in FIG. 5, the amount of oxygen showed no fluctuation with increasing time of mechanical alloying, indicating that oxidation of the raw material powder was not caused by mechanical alloying.

On the other hand, it is further confirmed that the Al powder is increased uniformly with the Al powder as the expansion graphite powder increases the mechanical alloying time.

Next, in step S20, the powder subjected to the mechanical alloying is compressed by a cold press to produce a predetermined compact (S30). Here, the powder subjected to the mechanical alloying for 30 minutes can be charged into a mold having an inner diameter of 10 mm at a pressure of about 5 tons and compressed to produce a molded article.

Subsequently, the molded body is sintered at a predetermined sintering temperature for a third time to produce the nanocomposite material of the present invention (S40).

Sintering was performed stepwise from 350 ° C to 550 ° C to confirm the sintering temperature.

Fig. 6 shows an X-ray diffraction pattern measured after sintering of an Al-powder and an expanded graphite powder subjected to mechanical alloying. 6 (a) shows the result of mixing Al powder and 10 wt% expanded graphite powder and sintering the pure Al powder at 550 ° C for 2 hours, FIG. 6 (b) shows the result of mechanical alloying in the ball mill, (c) to (h) are each subjected to mechanical alloying in a ball mill, followed by 2 hours at 350 ° C, 2 hours at 400 ° C, 2 hours at 450 ° C, 2 hours at 500 ° C, 2 hours at 550 ° C, It is the result of sintering.

As shown in Fig. 6, the compound phase of Al ₄ C ₃ appeared from the specimen sintered at 300 ° C for 2 hours. It is presumed that the extruded expanded graphite in the mechanical alloying is mixed with the Al powder to form the second phase, and as the sintering temperature and time are increased, more compound phase appears.

Considering that the compound phase has very good properties in terms of strength but it is a cause of lowering the thermal conductivity, it is normal to conduct the thermal conductivity measurement test on the sample sintered before 300 ° C. However, in the case of the sample sintered before 300 ° C. The density of about 70% of the theoretical density of Al was measured and it is considered that it would be difficult to obtain a very good thermal conductivity value.

FIG. 6 (a) shows the sintering characteristics of the pure Al powder prepared by sintering under the above conditions in order to compare the sintering characteristics with the mechanical alloying.

Fig. 7 shows the thermal conductivity measured after sintering of the Al alloy powder and the expanded graphite powder subjected to the mechanical alloying.

As shown in FIG. 7, the thermal conductivity (W / mK) of the sintered specimen produced at the time of day was 155 W / mK for the Al specimen, but significantly decreased when the expanded graphite was added , Which is considered to be due to the lowering of the sinter density relative to the theoretical density and the appearance of binary alloys such as Al ₄ C ₃ phase. As a result, it was confirmed that the thermal conductivity increased slightly as the sintering temperature and time were increased. As a result, the experiment that can increase the thermal conductivity of Al was that the third element And further experiments such as addition and sintering conditions should be carried out.

As described above, the product using the expanded graphite / metal (Al, etc.) composite developed according to the present invention is considered to be excellent in low heat resistance, weight reduction, cost reduction, environment friendliness and corrosion resistance. Its high competitiveness will contribute to the heat dissipation market for home appliances, and will contribute to the replacement of imports and exports with new businesses with LED makers and contribute to the development of local industries.

In addition, the radiator market in 2014 is expected to be 2 billion euros. In addition to the increase in outsourcing costs due to the rise in labor costs, it is inevitable that prices will increase due to rising prices of raw materials such as copper, iron and aluminum. Cost competitiveness can be secured by cost reduction and it is anticipated that more than 1 billion won of sales will be generated in the first year when applied to electronic devices and LEDs by creating heat-resistant products. Job creation and job creation are expected.

The present invention can also be embodied as computer-readable codes on a computer-readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and may be implemented in the form of a carrier wave (for example, transmission via the Internet) . The computer readable recording medium may also be distributed over a networked computer system so that computer readable code can be stored and executed in a distributed manner. In addition, functional programs, codes, and code segments for implementing the present invention can be easily inferred by programmers of the technical field to which the present invention belongs.

It should be understood that the above-described apparatus and method are not limited to the configuration and method of the embodiments described above, but the embodiments may be modified so that all or some of the embodiments are selectively combined .

Claims (8)

A first step of mechanically alloying Al powder and graphite powder for 2 hours using a ball mill to mix the Al powder and the graphite powder;
A second step of subjecting the mixed Al powder and the graphite powder to mechanical alloying for 20 minutes to 30 minutes;
A third step of compressing the powder subjected to the mechanical alloying in the second step with a cold press to produce a predetermined compact; And
And sintering the formed body at a temperature between 300 ° C and 400 ° C for 2 hours or 4 hours,
The ratio of the Al powder and the graphite powder mixed in the first step is 9: 1,
The second stage of mechanical alloying is a high energy ball mill process,
In the third step, the production of the molded article is carried out by charging the powder into a mold at a constant pressure and compressing the powder,
Characterized in that the graphite powder is expanded graphite expanded at a temperature of 400 ° C or more and 1000 ° C or higher after being immersed in a mixture of sulfuric acid and nitric acid. The graphite powder is manufactured by mechanical alloying of a graphite- Way.
delete delete delete delete delete delete A nanocomposite material produced by the method of manufacturing a nanocomposite material by mechanical alloying of the graphite-metal composite material according to claim 1.

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