JP6164632B2 - Method for producing carbon-based metal composite material - Google Patents

Description

  The present invention relates to a method for producing a carbon-based metal composite material that can be used as a material for a heat dissipation base or the like.

  Conventionally, the development of a material having a high thermal conductivity and a low coefficient of thermal expansion has been demanded as a material for a heat dissipation base and the like. Among these materials, a composite material in which a carbon material and a metal material are combined by filling the pores of the carbon material with a metal material has been proposed, and a manufacturing method by impregnating the carbon component with a metal component has been performed. Yes.

  However, in general, carbon materials and molten metal have poor wettability, and it has been difficult to sufficiently impregnate the pores of the carbon material with the molten metal component by the production method by impregnating the carbon material with the metal component. In particular, in the aluminum impregnation, there is a problem that the carbon component and the metal component react at the interface and the carbon material is deteriorated.

  On the other hand, in Patent Document 1, by adjusting the temperature of the molten metal impregnated into the carbon material and the pressure of the molten metal impregnated under pressure, the replacement ratio of the metal component to the pores of the carbon material is increased. The invention has been described. A carbon-based metal composite material having a high proportion of carbon components and high thermal conductivity is manufactured. Patent Document 2 describes an invention relating to a heat radiator combining such a carbon-based metal composite and an aluminum extruded material.

Japanese Patent No. 3673436 JP 2010-67842 A

  However, the invention described in Patent Document 1 has the following problems with the carbon material prepared for impregnating the metal material. That is, Patent Document 1 describes various materials as a carbon material having a graphite crystal-containing carbonaceous matrix. In order to obtain a carbon molded body having a graphite-based crystal, 2500 ° C. or more, particularly 2800 ° C. It is described that the baking treatment is performed at the above temperature. Similarly, Patent Document 2 describes that the graphite used is finally treated at 2500 ° C. or higher. Such a high-temperature firing treatment becomes a factor for increasing the cost of manufacturing a carbon molded body.

  In addition, demands for improving the thermal conductivity for use as a heat dissipation base have been increasing in recent years, and there is room for improvement in the thermal conductivity of carbon-based metal composite materials.

  The present invention solves the above-described conventional problems, and is a carbon-based metal composite material that is produced by producing a carbon molded body by a relatively low-temperature firing treatment to reduce costs and further increase the thermal conductivity. A manufacturing method is provided.

  The present inventors have focused on scaly natural graphite, which can be procured at a low cost and can give directionality to heat conduction, as a material for a carbon molded body used for a carbon-based metal composite material. The present invention has been completed.

  That is, the method for producing a carbon-based metal composite material according to the present invention includes a mixing step in which scaly natural graphite and pitch are mixed to form a mixture, and a firing of the mixture to form a carbon molded body having voids. And an impregnation step of impregnating molten metal into the voids of the carbon molded body.

  Preferably, the firing temperature in the firing step is 600 ° C to 2500 ° C.

  Preferably, the scaly natural graphite is scaly natural graphite on the 32 mesh sieve obtained by passing through a 32 mesh sieve.

  Preferably, the volume ratio at the time of mixing the scale-like natural graphite and the pitch is 98: 2 to 80:20.

  Preferably, the molten metal is aluminum.

  Preferably, the pitch is a mesophase pitch.

  According to the present invention, by using scaly natural graphite and pitch as a material for generating a mixture in the mixing step, it can be procured at a lower cost than artificial graphite or the like. Moreover, it is thought that scaly natural graphite can give directionality to heat conduction, and can be effectively used as a material such as a heat dissipation base. In the firing step, the mixture is fired to form a carbon molded body having voids, and in the impregnation step, the voids of the carbon molded body are impregnated with molten metal, thereby reducing the cost and increasing the thermal conductivity. A metal composite material can be obtained.

  Further, by setting the firing temperature in the firing step to 600 ° C. to 2500 ° C., it is possible to reduce the cost by producing a carbon molded body by a firing process at a relatively low temperature.

  Moreover, by using the scaly natural graphite on a 32 mesh sieve obtained by passing through a 32 mesh sieve as the material scaly natural graphite, it is possible to increase the thermal conductivity using a relatively large diameter graphite. .

  In addition, by setting the volume ratio at the time of mixing the scaly natural graphite and pitch to 98: 2 to 80:20, the mixing ratio of the pitch is reduced while maintaining the shape as the carbon molded body, and heat conduction is performed. The rate can be increased.

  Moreover, by using aluminum as the molten metal, the thermal conductivity and the thermal expansion coefficient can be improved while suppressing the cost.

  In addition, the use of mesophase pitch having a regular molecular structure as the pitch and suitable for heat treatment is effective for maintaining the shape of the carbon molded body.

  As described above, according to the present invention, it is possible to provide a method for producing a carbon-based metal composite material in which a carbon molded body is produced by relatively low-temperature firing treatment to reduce costs and to further increase thermal conductivity. it can.

It is a figure which shows the process of the manufacturing method of the carbon group metal composite material which concerns on embodiment of this invention. It is a figure which shows a mixing process. It is a figure which shows a baking process. It is a figure which shows an impregnation process.

  Hereinafter, with reference to FIGS. 1-4, the manufacturing method of the carbon group metal composite material which concerns on embodiment of this invention is demonstrated. First, materials used in the method for producing a carbon-based metal composite material according to the present embodiment will be described.

(Carbon component)
Graphite and pitch are used as the material of the carbon molded body that is the basis of the carbon-based metal composite material. The graphite used is scaly natural graphite. As the particle size of the scale-like natural graphite, those having various sizes can be used. From the viewpoint of improving the thermal conductivity, it is preferable to use a graphite having a relatively large diameter, and in particular, a 32-mesh sieve. It is preferable to use scaly natural graphite on a 32-mesh sieve obtained by the above. Also, the pitch used as the binder is not particularly limited, but from the viewpoint of maintaining the shape as the carbon molded body, it is preferable to use a mesophase pitch having a regular molecular structure and suitable for heat treatment.

(Metal component)
Examples of the metal component impregnated in the carbon molded body include aluminum, copper, and silver, but are not particularly limited. However, it is preferable to use aluminum from the viewpoint of the balance between thermal conductivity and thermal expansion coefficient and cost.

  Next, the process of the manufacturing method of the carbon group metal composite material which concerns on this embodiment is demonstrated. As shown in FIG. 1, the method for producing a carbon-based metal composite material according to the present embodiment includes a mixing process 10, a firing process 20, and an impregnation process 30.

(Mixing process)
In order to form a carbon molded body that is the basis of the carbon-based metal composite material, the mixture 3 is obtained by mixing the flaky natural graphite 1 and the pitch 2 in the mixing step 10 as shown in FIG. The mixing ratio between the scale-like natural graphite 1 and the pitch 2 is such that the scale-like natural graphite: pitch is 98: 2 in order to reduce the mixing ratio of the pitch and increase the thermal conductivity while maintaining the shape as the carbon molded body. It is preferable to be in the range of ˜70: 30. In particular, the range of 98: 2 to 80:20 is preferable.

  At the time of mixing, it mixes so that the pitch 2 used as a binder may spread over the entire scale-like natural graphite 1 as uniformly as possible. The method is not particularly limited, but it is effective to carry out the following method. First, the prepared pitch 2 is dissolved in alcohol. Next, the alcohol in which the pitch 2 is dissolved is mixed with the scaly natural graphite 1. Since alcohol becomes a lubricant during mixing, it can be mixed more uniformly by using more. As a result, the pitch 2 spreads over the entire scaly natural graphite 1 and the alcohol component is vaporized by the subsequent baking treatment.

  Further, since the scaly natural graphite 1 is originally flat, it is considered that heat conduction can be given direction by being laminated and fired in a flat state. Therefore, by performing cutting or the like while considering which direction has the higher thermal conductivity in the final shape processing, it can be effectively used as a material for the heat dissipation base or the like.

(Baking process)
Next, as shown in FIG. 3, the mixed mixture 3 is fired in the firing step 20. Firing may be performed by a conventionally known method. For example, an electric current sintering machine may be used in which the mixture 3 placed in the mold is energized and sintered while being pressed. The firing temperature at this time may be performed at a relatively low temperature, and may be in the range of 600 ° C. to 2500 ° C., for example. Although firing at a low temperature is advantageous in terms of cost, conventionally, firing has been performed at a temperature of 2500 ° C. or higher, particularly 2800 ° C. or higher for crystallization of graphite. In this embodiment, paying attention to the materials and processing methods to be used, the necessary thermal conductivity can be obtained even when firing at a relatively low temperature of 2500 ° C. or less. Note that 600 ° C. is a temperature at which impurities in the pitch to be used start to burn.

  The carbon forming body 4 having voids can be obtained by the firing step 20. In addition, since the void of the obtained carbon molded body 4 is impregnated with molten metal in the next impregnation step 30, the carbon molding is performed in consideration of the ratio of the metal component in the finally obtained carbon-based metal composite material. It is necessary to adjust the void ratio in the body. The ratio of the metal component to the carbon-based metal composite material finally obtained is preferably 20% to 40%. For this purpose, the pressure applied to the mixture 3 placed in the mold is appropriately adjusted.

(Impregnation process)
Next, as shown in FIG. 4, in the impregnation step 30, the molten metal 5 is impregnated in the carbon molded body 4 obtained in the firing step 20. Impregnation can be performed by a conventionally known method. The carbon-based metal composite material 6 is obtained by the impregnation step 30. The obtained carbon-based metal composite material 6 is appropriately processed according to the purpose of use.

Below, the Example about the manufacturing method of the carbon group metal composite material which concerns on this embodiment is shown.
(Implementation conditions)
-As the material of the carbon molded body, scaly natural graphite and mesophase pitch on a 32 mesh sieve obtained by passing through a 32 mesh sieve were used. The particle size of graphite was about 0.3 mm to 1.2 mm. In addition, two types of mesophase pitches, a middle size (M: 0.05 mm to 0.5 mm) and a small size (S: 0.05 mm or less), were used depending on the particle size. The mixture obtained by mixing these materials was energized while being pressed by an electric sintering machine, and the carbon molded body having voids was fired. The voids of the fired carbon molded body were impregnated with aluminum as a metal component to obtain a carbon-based metal composite material. While changing the ratio of each material and the firing temperature, seven types of samples were obtained.
-About the obtained sample, specific heat, specific gravity, and thermal diffusivity were measured, and thermal conductivity was computed by these products. Measurement was performed by a laser flash method, and “LFA457 manufactured by NETZSCH” was used as a measuring apparatus. In measuring the thermal conductivity, the sample was cut in advance so that it could be measured in the direction of high thermal conductivity (the direction along the flat shape of the laminated scaly natural graphite).

  The results measured according to the above operating conditions are shown in Table 1. In Table 1, “carbon molded body%” indicates the volume ratio of the carbon molded body when the carbon-based metal composite material (total of carbon component and metal component) is 100%. Further, “graphite%” and “pitch%” indicate volume ratios of graphite and pitch (M, S) when the carbon molded body (carbon component only) is 100%.

  As shown in Table 1, a carbon-based metal having a high thermal conductivity even when a carbon molded body is fired by a firing process at a relatively low temperature of 900 ° C., 1500 ° C., 2000 ° C., 2200 ° C. A composite material could be produced.

  According to the method for producing a carbon-based metal composite material according to the present embodiment, the scale-like natural graphite 1 and the pitch 2 are used as materials for generating the mixture 3 in the mixing step 10, which is cheaper than artificial graphite and the like. Can be procured at. Moreover, it is thought that the scale-like natural graphite 1 can give directionality to heat conduction, and can be effectively used as a material such as a heat dissipation base. Then, the mixture 3 is fired in the firing step 20 to form the carbon molded body 4 having voids, and the voids of the carbon molded body 4 are impregnated with the molten metal 5 in the impregnation step 30, thereby reducing heat and reducing heat conduction. A carbon-based metal composite material 6 with an increased rate can be obtained.

  In addition, by setting the firing temperature in the firing step 20 to 600 ° C. to 2500 ° C., the carbon molded body 4 can be manufactured by a relatively low temperature firing treatment to reduce costs.

  Moreover, by using the scaly natural graphite 1 on a 32 mesh sieve obtained by passing through a 32 mesh screen as the scaly natural graphite 1 of the material, using a relatively large diameter graphite, the thermal conductivity is increased. Can do.

  Moreover, the mixing ratio of pitch is made small, maintaining the shape as the carbon molded object 4, by setting the volume ratio at the time of mixing of the scale-like natural graphite 1 and the pitch 2 to 98: 2-80: 20. The thermal conductivity can be increased.

  Moreover, by using aluminum as the molten metal 5, the thermal conductivity and the thermal expansion coefficient can be improved while suppressing the cost.

  In addition, the use of mesophase pitch having a regular molecular structure and suitable for heat treatment as the pitch is effective in maintaining the shape of the carbon molded body 4.

  As described above, according to the present invention, it is possible to provide a method for producing a carbon-based metal composite material in which a carbon molded body is produced by relatively low-temperature firing treatment to reduce costs and to further increase thermal conductivity. it can.

  In addition, this invention is not limited to the said embodiment, A various other change is possible.

DESCRIPTION OF SYMBOLS 1 Scale-like natural graphite 2 Pitch 3 Mixture 4 Carbon molded object 5 Molten metal 6 Carbon group metal composite material 10 Mixing process 20 Firing process 30 Impregnation process

Claims (3)

A mixing step of mixing scaly natural graphite and mesophase pitch to form a mixture, a firing step of firing the mixture to form a carbon molded body having voids, and impregnating the voids of the carbon molded body with aluminum have a impregnation process,
As the scaly natural graphite, using scaly natural graphite on the 32 mesh sieve obtained by passing through a 32 mesh sieve,
A method for producing a carbon-based metal composite material, wherein two kinds of sizes of 0.05 mm to 0.5 mm and a size of 0.05 mm or less are used as the mesophase pitch .   The method for producing a carbon-based metal composite material according to claim 1, wherein a firing temperature in the firing step is 600 ° C to 2500 ° C. 3. The method for producing a carbon-based metal composite material according to claim 1, wherein a volume ratio at the time of mixing the scaly natural graphite and the mesophase pitch is 98: 2 to 80:20. .