JP6876569B2 - Metal-carbon particle composite - Google Patents

Description

The present invention relates to a metal-carbon particle composite material in which scaly graphite particles as carbon particles are dispersed in a metal matrix.

In the present specification and claims, the term "aluminum" is used to mean both pure aluminum and aluminum alloys, and the term "copper" is used to include pure copper and aluminum alloys, unless otherwise specified in the text. It is used to include both copper alloys.

Further, in the present specification, for convenience of explanation, the direction in which a plurality of metal layers and scaly graphite particle dispersion layers are alternately laminated in the metal-carbon particle composite material is defined as the thickness direction of the composite material, and the composite material is defined as the thickness direction. The plane perpendicular to the thickness direction of the composite and its direction are defined as the plane and the plane direction of the composite material, respectively.

Metal-carbon particle composites generally have high thermal conductivity and low linear expansion. The following are documents that disclose this type of composite material and its manufacturing method.

Patent No. 5150905 (Patent Document 1) forms a preform in which a film containing carbon fibers is formed on a sheet-shaped or foil-shaped metal support, and stacks a plurality of the preforms to form a laminated body. It discloses a method of producing a metal-based carbon fiber composite material as a metal-carbon particle composite material by heat-pressing a body. In this method, the obtained composite material has a high thermal conductivity only in one direction in which the carbon fibers are oriented.

In Japanese Patent Application Laid-Open No. 2015-25158 (Patent Document 2), a plurality of metal layers and carbon fiber layers are laminated alternately and metal layers are arranged on both outermost sides in the stacking direction, and these layers are laminated. Discloses a composite material of metal and carbon fiber, which is joined and integrated by diffusion bonding.

In this composite material, the metal layers arranged on both outermost sides in the thickness direction of the composite material (this is referred to as "outermost metal layer" for convenience of explanation) are arranged inside both outermost metal layers of the composite material. It is thicker than the metal layer (this is referred to as the "inner metal layer" for convenience of explanation). The reason is that the outermost metal layer mainly protects the outer surface of the composite to prevent the carbon fibers in the composite from being exposed to the outer surface of the composite or falling off from the outer surface of the composite. This is because it has a role as a protective layer.

According to Japanese Patent No. 4441768 (Patent Document 3), a sintered precursor is formed by using a mixture of scaly graphite powder and a predetermined scaly metal powder, and the sintered precursor is sintered to form a metal-carbon. It discloses a method for producing a particle composite material. This method has a problem that it is difficult to handle the metal powder at the time of manufacturing and the manufacturing cost is high.

Japanese Unexamined Patent Publication No. 2006-1232 (Patent Publication No. 4) provides a metal-carbon particle composite material by hot-press sintering a composite in which a plurality of crystalline carbon material layers and metal layers are alternately laminated and composited. Discloses a method for producing a high thermal conductivity / low thermal expansion composite material. In this method, it is difficult to sinter the composite, and therefore it is considered that the bonding is insufficient and the bonding interface is likely to be displaced.

As another document that discloses a metal-carbon particle composite material, there is Japanese Patent Application Laid-Open No. 2015-217655 (Patent Document 5).

Patent No. 5150905 Japanese Unexamined Patent Publication No. 2015-25158 Japanese Patent No. 4441768 Japanese Unexamined Patent Publication No. 2006-1232 Japanese Unexamined Patent Publication No. 2015-217655

Therefore, the next-generation semiconductor chip using SiC or the like can operate at a high temperature. It is desirable that the material of the constituent layer of the cooler for cooling such chips has higher thermal conductivity (high thermal conductivity) in order to enhance the cooling performance of the cooler. Therefore, it is conceivable to use a metal-carbon particle composite material as this material.

However, when carbon fibers are used as the carbon particles of the metal-carbon particle composite material, the composite material has high molding processability, but the carbon fibers are oriented to have high thermal conductivity in the composite material. Therefore, it is not easy to manufacture a composite material having a high thermal conductivity.

When scaly graphite particles are used as carbon particles in a metal-carbon particle composite material, a composite material having high thermal conductivity can be produced, but there is a drawback that the molding processability of the composite material is not very good. It was. Therefore, when the composite material is bent, for example, the layers constituting the composite material (that is, the metal layer and the scaly graphite particle layer) are likely to be peeled off or the composite material is easily broken.

The present invention has been made in view of the above-mentioned technical background, and an object of the present invention is to provide a metal-carbon particle composite material having high thermal conductivity and high molding processability.

The present invention provides the following means.

[1] A metal layer made of a metal matrix and a scaly graphite particle dispersion layer in which scaly graphite particles are dispersed in the metal matrix are joined and integrated in a state of being alternately laminated.
The average thickness of the metal layer is in the range of 12 to 100 μm.
The average thickness of the scaly graphite particle dispersion layer is in the range of 1 to 100 μm.
A metal-carbon particle composite material in which X is in the range of 0.1 to 1, where the ratio of the average thickness of the metal layer to the average thickness of the scaly graphite particle dispersion layer is 1: X.

[2] The metal-carbon particle composite material according to item 1 above, wherein the metal matrix is aluminum or copper.

The present invention has the following effects.

In the metal-carbon particle composite material according to item 1 above, since scaly graphite particles are used as carbon particles, a composite material having high thermal conductivity can be easily produced.

Further, the average thickness of the metal layer is in the range of 12 to 100 μm, the average thickness of the scaly graphite particle dispersion layer is in the range of 1 to 100 μm, and the average thickness of the metal layer and the average thickness of the scaly graphite particle layer. When the ratio with and to is 1: X, since X is in the range of 0.1 to 1, the metal layer is thick, which makes it possible to improve the moldability of the composite material.

In item 2 above, the thermal conductivity of the composite material can be reliably increased by using aluminum or copper as the metal matrix.

FIG. 1 is a schematic cross-sectional organizational chart of a metal-carbon particle composite material according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional organizational chart for explaining a method of calculating the average thickness of the metal layer and the average thickness of the scaly graphite particle layer. FIG. 3 is a flow chart of a method for manufacturing the composite material. FIG. 4 is a schematic view illustrating a process of obtaining a coating foil. FIG. 5 is a schematic view when cutting the strip material of the coating foil. FIG. 6 is a schematic front view of the laminated body. FIG. 7 is a schematic view of the case where the laminate is sintered by a pressure heating sintering apparatus.

Next, an embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the metal-carbon particle composite material 20 according to the embodiment of the present invention includes a plurality of metal layers (regions surrounded by an alternate long and short dash line) 22 composed of a metal matrix (indicated by dotted shading) 23. , A plurality of scaly graphite particle dispersion layers (regions surrounded by a two-dot chain line) 21 in which scaly graphite particles 1 as carbon particles are dispersed are included in the metal matrix 23. A plurality of the metal layer 22 and the scaly graphite particle dispersion layer 21 are arranged in a state of being alternately laminated in the thickness direction B of the composite material 20 over substantially the entire thickness direction B of the composite material 20. In this state, the plurality of metal layers 22 and the plurality of scaly graphite particle dispersion layers 21 are joined and integrated (more specifically, sintered and integrated), whereby the composite material 20 is formed.

Since the scaly graphite particles 1 are used as the carbon particles in the composite material 20, the composite material 20 is a metal-scaly graphite particle composite material in detail.

In each scaly graphite particle dispersion layer 21, a large number of scaly graphite particles 1 are dispersed in the metal matrix 23 in the plane direction A of the composite material 20.

It is desirable that the scaly graphite particles 1 have as high thermal conductivity as possible (eg, highly thermally conductive scaly graphite particles).

The particle size of the scaly graphite particles 1 is not limited, but when the length in the longest axial direction of the scaly graphite particles 1 is the particle size of the scaly graphite particles 1, they are dispersed in the metal matrix 23. It is desirable that the average length of a large number of scaly graphite particles 1 in the longest axial direction is 300 μm or more. In this case, the interfacial thermal resistance between the scaly graphite particles 1 and the metal matrix 23 can be reduced inside the composite material 20, whereby the thermal conductivity of the composite material 20 can be reliably increased. The upper limit of the average length of the scaly graphite particles 1 in the longest axial direction is not limited, and is usually 1000 μm.

Here, the average length of the scaly graphite particles 1 in the longest axial direction is calculated by the following method.

100 scaly graphite particles arbitrarily selected from a large number of scaly graphite particles dispersed on a glass plate are observed with an optical microscope, and the length of each scaly graphite particle in the longest direction is measured. Then, the arithmetic mean value thereof is taken as the average length in the longest axial direction of the scaly graphite particles.

The aspect ratio of the scaly graphite particles 1 is not limited, and it is particularly desirable that the average aspect ratio thereof is 30 or more. The desired upper limit of the average aspect ratio of the scaly graphite particles 1 is also not limited, and is usually 100.

The type of the metal matrix 23 is not limited, but it is particularly desirable that the metal matrix 23 is aluminum or copper. In this case, the thermal conductivity of the composite material 20 can be reliably increased.

In the composite material 20 of the present embodiment, since the scaly graphite particles 1 are used as the carbon particles, the composite material 20 having a high thermal conductivity can be easily produced.

In the composite material 20 of the present embodiment, the average thickness of the metal layer 22 and the average thickness of the scaly graphite particle dispersion layer 21 are defined by the following methods.

As shown in FIG. 2, the cross section of the composite material 20 cut in the thickness direction B has a viewing range of 1.5 mm (planar direction A of the composite material 20) × 1.0 mm (thickness direction B of the composite material 20). In the cross-sectional structure photograph of the composite material 20, when 10 grid lines 60 extending in the thickness direction B of the composite material 20 are drawn in the plane direction A of the composite material 20 at intervals of 0.1 mm, one grid line 60 is one. The length t of the line segment crossing the scaly graphite particles 1 was measured as the thickness of one scaly graphite particle dispersion layer 21, and all the scaly graphite particle dispersion layers 21 measured for 10 grid lines 60. The arithmetic average value of the thickness is defined as the average thickness of the scaly graphite particle dispersion layer 21, and one grid line 60 is one metal matrix portion (that is, two adjacent grid lines 60 crossing each other. The length T of the line segment crossing the scaly graphite particles 1, 1) was measured as the thickness of one metal layer 22, and the thickness of all the metal layers 22 measured for 10 grid lines 60. The arithmetic average value of the dimension is defined as the average thickness of the metal layer 22.

However, the metal layers arranged on both outermost sides of the composite material 20 in the thickness direction B, that is, the outermost metal layers, are excluded from the metal layers applied to the calculation of the average thickness of the metal layer 22. The reason is that the outermost metal layer is generally arranged inside both outermost metal layers of the composite material 20 (that is, in order to have a role as a protective layer for protecting the outer surface of the composite material 20). This is because it is often thicker than the inner metal layer) 22.

In the composite material 20 of the present embodiment, the average thickness of the metal layer 22 is set in the range of 12 to 100 μm, and the average thickness of the scaly graphite particle dispersion layer 21 is set in the range of 1 to 100 μm. When the ratio of the average thickness of the metal layer 22 to the average thickness of the scaly graphite particle dispersion layer 21 is 1: X, X is set in the range of 0.1 to 1.

By setting the average thickness of the metal layer 22, the average thickness of the scaly graphite particle dispersion layer 21, and X to the above-mentioned ranges, the thermal conductivity of the composite material 20 can be increased, and the composite material 20 can be increased. Molding workability (eg, bending workability, ductility, punching workability) can be improved.

When X is less than 0.1, the content of the scaly graphite particles 1 in the composite material 20 is too small, and therefore the effect of increasing the thermal conductivity of the composite material 20 is inferior. When X exceeds 1, the content of the scaly graphite particles 1 in the composite material 20 is too large, which makes it difficult to manufacture the composite material 20 and deteriorates the molding processability of the composite material 20.

A particularly desirable thickness of the metal layer 22 is in the range of 15 to 50 μm, and a particularly desirable thickness of the scaly graphite particle dispersion layer 21 is in the range of 10 to 35 μm. Further, it is particularly desirable that X is in the range of 0.2 to 0.7.

Further, the volume content of the scaly graphite particles 1 in the composite material 20 is preferably in the range of 10 to 50% by volume with respect to the volume of the composite material 20. In this case, the moldability of the composite material 20 can be reliably improved.

The method for producing the composite material 20 is not limited, but a desirable method for producing the composite material 20 will be described below with reference to FIGS. 3 to 7.

As shown in FIG. 3, the method for producing the composite material 20 includes a step S1 for obtaining a coating foil, a step S2 for forming a laminate, and a step S3 for sintering the laminate. It is done in order.

In the step S1 of obtaining the coating foil, as shown in FIG. 4, the coating liquid 5 containing the scaly graphite particles 1, the binder 2 and the binder 2 solvent 3 in a mixed state is applied to the surface 10a of the metal foil 10 to be coated. To obtain a coating foil 12 in which the scaly graphite particle layer 11 is formed on the surface 10a to be coated of the metal foil 10.

In the present embodiment, the strip-shaped strip 10A of the metal foil 10 (that is, the strip-shaped long metal foil 10) is used as the metal foil 10.

The planned coating surface 10a of the strip material 10A of the metal foil 10 is at least one surface of both surfaces of the strip material 10A of the metal foil 10 in the thickness direction, and in the present embodiment, the planned coating surface 10a is the metal foil. Only one surface of the 10 strips 10A in the thickness direction.

The metal material of the metal foil 10 is determined according to the type of metal matrix 23 of the desired composite material 20. That is, when the metal matrix 23 is an aluminum matrix, an aluminum foil is used as the metal foil 10, and when the metal matrix 23 is a copper matrix, a copper foil is used as the metal foil 10.

When the metal foil 10 is an aluminum foil, the material of the aluminum foil is not limited, and is, for example, pure aluminum or an aluminum alloy having a purity of 99% or more.

When the metal foil 10 is a copper foil, the material of the copper foil is not limited, and is, for example, pure copper or a copper alloy.

The thickness of the metal foil 10 may be such that the average thickness of the metal layer 22 of the obtained composite material 20 is in the range of 12 to 100 μm. Here, when the thickness of the metal foil 10 is 10 μm or less, the material cost of the metal foil 10 is high and the handleability of the metal foil 10 is poor. Therefore, it is desirable that the thickness of the metal foil 10 exceeds 10 μm. ..

The binder 2 imparts the adhesive force of the strip material 10A of the metal foil 10 to the planned coating surface 10a to the scaly graphite particles 1 to prevent the scaly graphite particles 1 from accidentally falling off from the planned coating surface 10a. It is for doing. The binder 2 is usually made of a resin such as an organic resin. As the binder 2, polyethylene oxide, polyvinyl alcohol, acrylic resin and the like are used.

The solvent 3 dissolves the binder 2. As the solvent 3, a hydrophilic solvent (isopropyl alcohol, water), an organic solvent, or the like is used.

The coating liquid 5 is obtained, for example, as follows.

That is, the coating liquid 5 is obtained by putting the scaly graphite particles 1, the binder 2 and the solvent 3 in the mixing container 41 and mixing them with the stirring mixer 42. If necessary, a dispersant (not shown), a surface conditioner (not shown), or the like is added to the coating liquid 5. As the stirring mixer 42, a dispenser, a planetary mixer, a bead mill or the like is used.

The method and the coating apparatus for applying the coating liquid 5 to the planned coating surface 10a of the strip material 10A of the metal foil 10 are not limited. For example, as a coating device for the coating liquid 5, a gravure coater, a three-roll coater (offset type), a knife coater, a die coater, a roll coater (two rolls), a spray coater, a curtain coater, a reverse roll coater, or the like is used. Be done.

In the present embodiment, as shown in FIG. 4, the coating of the coating liquid 5 involves the unwinding roll 37a for unwinding the strip 10A of the metal foil 10 and the strip 10A of the metal foil 10 (the strip of the coating foil 12). This is performed by a roll-to-roll type coating device using a take-up roll 37b for winding the material 12A). The coating method of the coating liquid 5 in this case is as follows.

A coating device 30 and a drying furnace 38 are installed side by side in the feeding direction F of the strip 10A of the metal foil 10 between the unwinding roll 37a and the winding roll 37b.

The coating device 30 is, for example, a gravure coater (specifically, a direct gravure coater), and the coating liquid adhering means 35 for adhering the gravure roll 31, the backup roll 33, and the coating liquid 5 to the peripheral surface 31a of the gravure roll 31, the doctor. It is equipped with a blade 34 and the like.

A large number of cells (not shown) are arranged in an orderly manner on the peripheral surface 31a of the gravure roll 31 over the entire surface 31a. The cells include a grid cell, a pyramid cell, a hexagonal cell, a circular cell, a diagonal cell, and the like.

The coating liquid adhering means 35 includes a coating liquid pan (not shown) containing the coating liquid 5, and a part of the peripheral surface 31a of the gravure roll 31 in the circumferential direction is coated in the pan. The gravure roll 31 rotates about its central axis in contact with the liquid 5, so that the coating liquid 5 adheres to the peripheral surface 31a of the gravure roll 31 in the circumferential direction.

The strip 10A of the metal foil 10 unwound from the unwinding roll 37a passes between the gravure roll 31 and the backup roll 33 of the gravure coater (coating apparatus 30). At this time, the coating liquid 5 is applied to the planned coating surface 10a of the strip 10A of the metal foil 10 by the gravure roll 31 in the length direction of the strip 10A of the metal foil 10 (that is, the feed direction F of the strip 10A of the metal foil 10). ) Is continuously coated in layers. As a result, the strip 12A of the coating foil 12 in which the scaly graphite particle layer 11 composed of the coating liquid 5 is formed (coated) on the planned coating surface 10a of the strip 10A of the metal foil 10 is obtained.

Then, as the strip 12A of the coating foil 12 passes through the drying furnace 38, the solvent 3 in the scaly graphite particle layer 11 is evaporated and removed from the scaly graphite particle layer 11. After that, the strip 12A of the coating foil 12 is wound around the winding roll 37b.

The amount of the coating liquid 5 applied to the planned coating surface 10a of the strip material 10A of the metal foil 10 is not limited. In particular, the coating liquid 5 is a surface to be coated so that the coating amount of the scaly graphite particles 1 in the scaly graphite particle layer 11 is 10 to 160 g / m ² (preferably 25 to 80 g / m ^2). It is desirable that the coating be applied to 10a.

The step S2 for forming the laminated body is a step of forming the laminated body 15 in a state where a plurality of coating foils 12 are laminated, and is performed as follows, for example.

As shown in FIG. 5, first, the strip 12A of the coating foil 12 unwound from the take-up roll 37b is cut into a predetermined shape by the cutting machine 45. As a result, a plurality of coating foils 12 having a predetermined shape (eg, substantially rectangular shape) are cut out from the strip 12A of the coating foil 12. That is, each coating foil 12 is made of a cut piece obtained by cutting the strip 12A of the coating foil 12.

Next, as shown in FIG. 6, a plurality of coating foils 12 are laminated. As a result, the laminated body 15 in which a plurality of coating foils 12 are laminated is formed.

When laminating the coating foil 12, it is desirable that metal particles as a sintering auxiliary material are not interposed between the coating foils 12 and 12 that overlap each other. In this case, the laminated body 15 can be easily formed. As the metal particles, a metal powder of the same type as the metal foil 10 is used. However, in the present embodiment, the present invention is not limited to not interposing the metal particles between the coating foils 12 and 12 that overlap each other, and the metal particles may be interposed.

The number of laminated coating foils 12 for forming the laminated body 15 is not limited, and is set according to the desired thickness of the composite material 20, for example, 10 to 1000 sheets.

Here, in the case of producing a composite material in which a metal layer as a protective layer is arranged on the outermost side in the thickness direction, such as the composite material described in Japanese Patent Application Laid-Open No. 2015-25158 (Patent Document 2). In the above, when a plurality of coating foils 12 are laminated, a metal foil for a protective layer (the metal foil is a scaly graphite particle layer or the like) on the outermost side of the laminated body 15 in the thickness direction. (Does not have a carbon particle layer) is laminated. The protective layer protects the outer surface of the composite material 20 in order to prevent the scaly graphite particles 1 in the composite material 20 from being exposed to the outer surface of the composite material 20 or falling off from the outer surface of the composite material 20. It has a role, and its thickness is usually thicker than that of the metal leaf 10 of the coating foil 12.

In the step S3 of sintering the laminated body 15, the laminated body 15 is sintered by heating while uniaxially pressing in a predetermined sintering atmosphere (eg, non-oxidizing atmosphere), whereby a plurality of coating foils 12 are used. Are collectively joined and integrated (more specifically, sintered integration).

The sintering method of the laminated body 15 is selected from a vacuum hot press method, a discharge plasma sintering method (SPS method), a hot hydrostatic pressure sintering method (HIP method), a rolling method and the like.

Specifically, as shown in FIG. 7, for example, the laminated body 15 is arranged in the sintering chamber 51 of the pressure heating sintering apparatus 50, and the laminated body 15 is thickened in a predetermined sintering atmosphere. The laminated body 15 is sintered by heating under predetermined sintering conditions while pressurizing in the vertical direction (that is, the laminating direction of the coating foil 12). As a result, the metal-carbon particle composite material 20 having the cross-sectional structure shown in FIG. 1 is obtained.

The sintering device 50 can pressurize the laminated body 15 uniaxially, and includes, for example, a pair of pressing punches 52, 52 as the means. Both pressing punches 52 and 52 are arranged so as to face each other.

The pressure applied to the laminated body 15 is performed by sandwiching the laminated body 15 in the thickness direction between the double pressing punches 52 and 52 and pressurizing the laminated body 15. Therefore, the pressurizing direction of the laminated body 15 is the thickness direction of the laminated body 15, and this direction coincides with the thickness direction of the composite material 20 (B, see FIG. 1). That is, the thickness direction B of the composite material 20 coincides with the pressure direction of the laminated body 15.

The heating temperature of the laminate 15 for sintering the laminate 15, that is, the sintering temperature of the laminate 15 is not limited, and is usually equal to or lower than the melting point of the metal material of the metal foil 10, for example, the metal material. It is set to a temperature between the melting point of the above and a temperature about 50 ° C. lower than the melting point. Specifically, when the metal foil 10 is, for example, an aluminum foil, the sintering temperature of the laminated body 15 is set to, for example, 550 to 620 ° C.

The binder 2 existing in the laminate 15 disappears due to sublimation, dispersion, etc. during heating of the laminate 15 so that the temperature of the laminate 15 rises from approximately room temperature to the sintering temperature of the laminate 15 in this step S3. Then, it is removed from the laminated body 15.

In this step S3, when the laminate 15 is pressurized and heated as described above, a part of the metal material of the metal foil 10 permeates into the scaly graphite particle layer 11 and enters the scaly graphite particle layer 11. The existing fine voids (eg, gaps between the scaly graphite particles in the scaly graphite particle layer 11) are filled, and the voids are substantially extinguished. As a result, the density of the composite material 20 is increased and the strength of the composite material 20 is improved. Further, the scaly graphite particles 1 are oriented in the plane direction A of the composite material 20.

Further, a part of the metal material of the metal foil 10 permeates into the scaly graphite particle layer 11, so that the scaly graphite particles 1 in each scaly graphite particle layer 11 are composited in the metal matrix 23 of the composite material 20. The material 20 is dispersed in the plane direction A, that is, each scaly graphite particle layer 11 becomes the scaly graphite particle dispersion layer 21 of the composite material 20 as shown in FIG. Further, each metal foil 10 becomes a metal layer 22 of the composite material 20.

Therefore, in the composite material 20, the scaly graphite particle dispersion layer 21 and the metal layer 22 are alternately plurality in the thickness direction B of the composite material 20 over substantially the entire thickness direction of the composite material 20 as described above. Arrange in a stacked state.

Since the composite material 20 of the present embodiment has high thermal conductivity as described above, it can be suitably used as a material for the constituent layer of the cooler for the power module, and is a lithium ion secondary battery (LiB). ) Can be suitably used as a material for the constituent members of the battery. The power module is used in vehicles such as hybrid electric vehicles (HEVs), electric vehicles (EVs), and trains, and is used in the energy field such as wind power generation and solar power generation.

When the composite material 20 is used as a material for a constituent layer of a power module cooler, the composite material 20 may be a wiring layer, a buffer layer, a heat radiating layer (eg, a heat sink), etc. among a plurality of layers constituting the cooler. Especially preferably used for materials.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be variously modified without departing from the gist of the present invention.

Next, specific examples and comparative examples of the present invention are shown below. However, the present invention is not limited to the following examples.

<Example 1>
In Example 1, a metal-carbon particle composite was produced by the following procedure.

In a mixing container, scaly graphite particles as carbon particles, a 3% by mass aqueous solution of polyethylene oxide as a binder, a 10% by mass aqueous solution of polyvinyl alcohol, isopropyl alcohol and water as solvents, a dispersant and a surface conditioner are mixed. These were stirred and mixed with a disper to obtain a coating liquid. The viscosity of the coating liquid was 1000 mPa · s at 25 ° C.

The average length of the scaly graphite particles in the longest axial direction was 300 μm, and the average aspect ratio of the scaly graphite particles was 30. The content of the scaly graphite particles contained in the coating liquid was 90% by mass with respect to the total mass of the binder and the scaly graphite particles.

A roll-to-roll gravure coater (specifically, a direct gravure coater) is used to coat the surface of the aluminum foil (Al foil) strip-shaped strip material in layers at a coating speed of 2 m / min. As a result, a strip of coated foil having a scaly graphite particle layer formed on the surface to be coated of the strip of aluminum foil was obtained.

The material of the strip of aluminum foil was JIS (Japanese Industrial Standards) aluminum alloy number 1N30 (hereinafter, simply referred to as "A1N30"), the thickness of which was 50 μm and the width of which was 300 mm. The surface of the aluminum foil strip to be coated was one side of the aluminum foil strip in the thickness direction.

Then, the solvent in the scaly graphite particle layer was evaporated and removed from the scaly graphite particle layer by passing the strip of the coating foil through the drying furnace. The coating amount of the scaly graphite particles in the scaly graphite particle layer was 80 g / m ² .

Next, the strip of the coating foil was cut into a square shape (its dimensions: width 50 mm × length 50 mm), and a plurality of square coating foils were cut out from the strip of the coating foil. Then, a laminated body was formed by laminating 12 coating foils.

Next, a discharge plasma sintering device (SPS device) as a pressure heating sintering device pressurizes the laminate in the thickness direction (that is, the lamination direction of the coating foil) in a vacuum atmosphere while determining predetermined sintering conditions. The laminate was sintered by heating with. As a result, an aluminum-scaly graphite particle composite material as a metal-carbon particle composite material was obtained. The thickness of the composite material was 1 mm. The volume content of the scaly graphite particles in the composite material was 40% by volume with respect to the volume of the composite material.

The sintering conditions applied to this sintering were as follows.

The sintering temperature is 620 ° C., the holding time of the sintering temperature (that is, the sintering time) is 3 hours, the rate of temperature rise from room temperature is 20 ° C./min, the pressing force on the laminate is 20 MPa, and the degree of vacuum is 3 Pa. It was. Further, the binder was removed from the laminate by temporarily stopping the temperature rise while heating the laminate from room temperature to the sintering temperature of 620 ° C. The conditions for removing the binder applied at this time were as follows.

The heating temperature of the laminate for removing the binder was 450 ° C., and the holding time was 30 min.

In the composite material, aluminum as a metal matrix has sufficiently penetrated between the scaly graphite particles, there are almost no voids inside the composite material, and the density of the composite material is 99% of the theoretical density of the composite material. The sintered state of the composite material was good.

The thermal conductivity of the composite material in the plane direction was 442 W / (m · K), which was higher than the thermal conductivity of aluminum.

In addition, the cross section of the composite material cut in the thickness direction was photographed with an optical microscope (magnification: 75 times) in a visual field range of 1.5 mm (planar direction of the composite material) x 1.0 mm (thickness direction of the composite material). The average thickness of the aluminum layer and the average thickness of the scaly graphite particle dispersion layer were calculated according to the definitions described in the above-described embodiment, respectively, using the cross-sectional microstructure photograph. As a result, the average thickness of the aluminum layer was 52 μm, and the average thickness of the scaly graphite particle dispersion layer was 33 μm. Therefore, X was 0.63.

Further, a 50 mm × 10 mm bending test piece (thickness 1 mm) was cut out from the composite material, and the test piece was bent 90 ° with a bending radius of 3 mm. As a result, the aluminum layer and the scaly graphite particle dispersion layer of the test piece were obtained. No systematic peeling or breakage was observed.

<Example 2>
The same coating liquid as the coating liquid used in Example 1 was prepared. Moreover, as the strip material of the metal foil, the strip material of the aluminum foil having the following composition was prepared.

The material of the strip material of the aluminum foil was A1N30, the thickness of which was 15 μm, and the width of which was 300 mm. The surface of the aluminum foil strip to be coated was one side of the aluminum foil strip in the thickness direction.

Next, the coating liquid was applied to the planned coating surface of the aluminum foil strip by the same coating method as in Example 1, whereby a scaly graphite particle layer was formed on the planned coating surface of the aluminum foil strip. A strip of coated foil was obtained.

Then, the solvent in the scaly graphite particle layer was evaporated and removed from the scaly graphite particle layer by passing the strip of the coating foil through the drying furnace. The coating amount of the scaly graphite particles in the scaly graphite particle layer was 25 g / m ² .

Next, a plurality of coating foils having the same dimensions and shapes as in Example 1 were cut out from the strip material of the coating foil. Then, a laminated body was formed by laminating 40 coating foils.

Next, the laminate was sintered under the same sintering apparatus and sintering conditions as in Example 1 to obtain an aluminum-scaly graphite particle composite material. The thickness of the composite material was 1 mm. The volume content of the scaly graphite particles in the composite material was 40% by volume with respect to the volume of the composite material.

In the composite material, aluminum as a metal matrix has sufficiently penetrated between the scaly graphite particles, there are almost no voids inside the composite material, and the density of the composite material is 99% of the theoretical density of the composite material. The sintered state of the composite material was good.

The thermal conductivity of the composite material in the plane direction was 436 W / (m · K), which was higher than the thermal conductivity of aluminum.

Further, when the average thickness of the aluminum layer of the composite material and the average thickness of the scaly graphite particle dispersion layer were calculated by the same method as in Example 1, the average thickness of the aluminum layer was 16 μm, and the scaly graphite particle dispersion layer had an average thickness of 16 μm. The average thickness was 10 μm. Therefore, X was 0.63.

Further, when a bending test piece having the same dimensions and shape as in Example 1 was cut out from the composite material and the test piece was bent under the same bending conditions as in Example 1, the aluminum layer and scaly graphite particles of the test piece were obtained. No systematic peeling or breakage was observed in the dispersed layer.

<Example 3>
The same coating liquid as the coating liquid used in Example 1 was prepared. Moreover, as the strip material of the metal foil, the strip material of the aluminum foil having the following composition was prepared.

The material of the strip of aluminum foil was A1N30, the thickness of which was 20 μm, and the width of which was 300 mm. The surface of the aluminum foil strip to be coated was one side of the aluminum foil strip in the thickness direction.

Next, the coating liquid was applied to the planned coating surface of the aluminum foil strip by the same coating method as in Example 1, whereby a scaly graphite particle layer was formed on the planned coating surface of the aluminum foil strip. A strip of coated foil was obtained.

Then, the solvent in the scaly graphite particle layer was evaporated and removed from the scaly graphite particle layer by passing the strip of the coating foil through the drying furnace. The coating amount of the scaly graphite particles in the scaly graphite particle layer was 10 g / m ² .

Next, a plurality of coating foils having the same dimensions and shapes as in Example 1 were cut out from the strip material of the coating foil. Then, a laminated body was formed by laminating 40 coating foils.

Next, the laminate was sintered under the same sintering apparatus and sintering conditions as in Example 1 to obtain an aluminum-scaly graphite particle composite material. The thickness of the composite material was 1 mm. The volume content of the scaly graphite particles in the composite material was 17% by volume with respect to the volume of the composite material.

In the composite material, aluminum as a metal matrix has sufficiently penetrated between the scaly graphite particles, there are almost no voids inside the composite material, and the density of the composite material is 99% of the theoretical density of the composite material. The sintered state of the composite material was good.

The thermal conductivity of the composite material in the plane direction was 320 W / (m · K), which was higher than the thermal conductivity of aluminum.

Further, when the average thickness of the aluminum layer of the composite material and the average thickness of the scaly graphite particle dispersion layer were calculated by the same method as in Example 1, the average thickness of the aluminum layer was 21 μm, and the scaly graphite particle dispersion layer had an average thickness of 21 μm. The average thickness was 4 μm. Therefore, X is was 0.1 9.

Further, when a bending test piece having the same dimensions and shape as in Example 1 was cut out from the composite material and the test piece was bent under the same bending conditions as in Example 1, the aluminum layer and scaly graphite particles of the test piece were obtained. No systematic peeling or breakage was observed in the dispersed layer.

<Example 4>
The same coating liquid as the coating liquid used in Example 1 was prepared. Moreover, as the strip material of the metal foil, the strip material of the aluminum foil having the following composition was prepared.

The material of the strip material of the aluminum foil was A1N30, the thickness of which was 15 μm, and the width of which was 300 mm. The surface of the aluminum foil strip to be coated was one side of the aluminum foil strip in the thickness direction.

Next, the coating liquid was applied to the planned coating surface of the aluminum foil strip by the same coating method as in Example 1, whereby a scaly graphite particle layer was formed on the planned coating surface of the aluminum foil strip. A strip of coated foil was obtained.

Then, the solvent in the scaly graphite particle layer was evaporated and removed from the scaly graphite particle layer by passing the strip of the coating foil through the drying furnace. The coating amount of the scaly graphite particles in the scaly graphite particle layer was 36 g / m ² .

Next, a plurality of coating foils having the same dimensions and shapes as in Example 1 were cut out from the strip material of the coating foil. Then, a laminated body was formed by laminating 33 coating foils.

Next, the laminate was sintered under the same sintering apparatus and sintering conditions as in Example 1 to obtain an aluminum-scaly graphite particle composite material. The thickness of the composite material was 1 mm. The volume content of the scaly graphite particles in the composite material was 50% by volume with respect to the volume of the composite material.

In the composite material, aluminum as a metal matrix has sufficiently penetrated between the scaly graphite particles, there are almost no voids inside the composite material, and the density of the composite material is 99% of the theoretical density of the composite material. The sintered state of the composite material was good.

The thermal conductivity of the composite material in the plane direction was 522 W / (m · K), which was higher than the thermal conductivity of aluminum.

Further, when the average thickness of the aluminum layer of the composite material and the average thickness of the scaly graphite particle dispersion layer were calculated by the same method as in Example 1, the average thickness of the aluminum layer was 16 μm, and the scaly graphite particle dispersion layer had an average thickness of 16 μm. The average thickness was 15 μm. Therefore, X was 0.94.

Further, when a bending test piece having the same dimensions and shape as in Example 1 was cut out from the composite material and the test piece was bent under the same bending conditions as in Example 1, the aluminum layer and scaly graphite particles of the test piece were obtained. No systematic peeling or breakage was observed in the dispersed layer.

<Example 5>
The same coating liquid as the coating liquid used in Example 1 was prepared. Further, as a strip material of the metal foil, a strip material of copper foil (Cu foil) having the following composition was prepared.

The material of the strip of copper foil was C1020, the thickness of which was 50 μm, and the width of which was 300 mm. In addition, the planned coating surface of the copper foil strip was the surface on one side of the copper foil strip in the thickness direction.

Next, the coating liquid was applied to the planned coating surface of the copper foil strip by the same coating method as in Example 1, whereby a scaly graphite particle layer was formed on the planned coating surface of the copper foil strip. A strip of coated foil was obtained.

Then, the solvent in the scaly graphite particle layer was evaporated and removed from the scaly graphite particle layer by passing the strip of the coating foil through the drying furnace. The coating amount of the scaly graphite particles in the scaly graphite particle layer was 80 g / m ² .

Next, a plurality of coating foils having the same dimensions and shapes as in Example 1 were cut out from the strip material of the coating foil. Then, a laminated body was formed by laminating 12 coating foils.

Next, the laminate was sintered by heating the laminate under predetermined sintering conditions while pressurizing the laminate in the thickness direction in a vacuum atmosphere with a discharge plasma sintering apparatus. As a result, a copper-scaly graphite particle composite material as a metal-carbon particle composite material was obtained. The thickness of the composite material was 1 mm. The volume content of the scaly graphite particles in the composite material was 40% by volume with respect to the volume of the composite material.

In the composite material, copper as a metal matrix has sufficiently penetrated between the scaly graphite particles, there are almost no voids inside the composite material, and the density of the composite material is 99% of the theoretical density of the composite material. The sintered state of the composite material was good.

The thermal conductivity of the composite material in the plane direction was 530 W / (m · K), which was higher than the thermal conductivity of copper.

Further, when the average thickness of the copper layer of the composite material and the average thickness of the scaly graphite particle dispersion layer were calculated by the same method as in Example 1, the average thickness of the copper layer was 53 μm, and the scaly graphite particle dispersion layer had an average thickness of 53 μm. The average thickness was 33 μm. Therefore, X was 0.62.

Further, when a bending test piece having the same dimensions and shape as in Example 1 was cut out from the composite material and the test piece was bent under the same bending conditions as in Example 1, the copper layer and scaly graphite particles of the test piece were obtained. No systematic peeling or breakage was observed in the dispersed layer.

<Comparative example 1>
The same coating liquid as the coating liquid used in Example 1 was prepared. Moreover, as the strip material of the metal foil, the strip material of the aluminum foil having the following composition was prepared.

The material of the strip of aluminum foil was A1N30, the thickness of which was 6 μm, and the width of which was 300 mm. The surface of the aluminum foil strip to be coated was one side of the aluminum foil strip in the thickness direction.

Next, the coating liquid was applied to the planned coating surface of the aluminum foil strip by the same coating method as in Example 1, whereby a scaly graphite particle layer was formed on the planned coating surface of the aluminum foil strip. A strip of coated foil was obtained.

Then, the solvent in the scaly graphite particle layer was evaporated and removed from the scaly graphite particle layer by passing the strip of the coating foil through the drying furnace. The coating amount of the scaly graphite particles in the scaly graphite particle layer was 10 g / m ² .

Next, a plurality of coating foils having the same dimensions and shapes as in Example 1 were cut out from the strip material of the coating foil. Then, a laminated body was formed by laminating 100 sheets of coating foil.

Next, the laminate was sintered under the same sintering apparatus and sintering conditions as in Example 1 to obtain an aluminum-scaly graphite particle composite material. The thickness of the composite material was 1 mm. The volume content of the scaly graphite particles in the composite material was 40% by volume with respect to the volume of the composite material.

In the composite material, aluminum as a metal matrix has sufficiently penetrated between the scaly graphite particles, there are almost no voids inside the composite material, and the density of the composite material is 99% of the theoretical density of the composite material. The sintered state of the composite material was good.

The thermal conductivity of the composite material in the plane direction was 438 W / (m · K), which was higher than the thermal conductivity of aluminum.

Further, when the average thickness of the aluminum layer of the composite material and the average thickness of the scaly graphite particle dispersion layer were calculated by the same method as in Example 1, the average thickness of the aluminum layer was 6 μm, and the scaly graphite particle dispersion layer had an average thickness of 6 μm. The average thickness was 4 μm. Therefore, X was 0.67.

Further, when a bending test piece having the same dimensions and shape as in Example 1 was cut out from the composite material and the test piece was bent under the same bending conditions as in Example 1, the aluminum layer and scaly graphite particles of the test piece were obtained. Systematic peeling and fracture were observed for the dispersed layer.

<Comparative example 2>
The same coating liquid as the coating liquid used in Example 1 was prepared. Moreover, as the strip material of the metal foil, the strip material of the aluminum foil having the following composition was prepared.

The material of the strip material of the aluminum foil was A1N30, the thickness of which was 15 μm, and the width of which was 300 mm. The surface of the aluminum foil strip to be coated was one side of the aluminum foil strip in the thickness direction.

Next, the coating liquid was applied to the planned coating surface of the aluminum foil strip by the same coating method as in Example 1, whereby a scaly graphite particle layer was formed on the planned coating surface of the aluminum foil strip. A strip of coated foil was obtained.

Then, the solvent in the scaly graphite particle layer was evaporated and removed from the scaly graphite particle layer by passing the strip of the coating foil through the drying furnace. The coating amount of the scaly graphite particles in the scaly graphite particle layer was 80 g / m ² .

Next, a plurality of coating foils having the same dimensions and shapes as in Example 1 were cut out from the strip material of the coating foil. Then, a laminated body was formed by laminating 20 coating foils.

Next, the laminate was sintered under the same sintering apparatus and sintering conditions as in Example 1 to obtain an aluminum-scaly graphite particle composite material. The thickness of the composite material was 1 mm. The volume content of the scaly graphite particles in the composite material was 70% by volume with respect to the volume of the composite material.

In the composite material, aluminum as a metal matrix does not penetrate much between the scaly graphite particles, and voids exist between the scaly graphite particles and the aluminum foil inside the composite material, respectively, and the composite material is fired. The bonding condition was not very good, and the thermal conductivity of the composite material could not be measured.

Further, when the average thickness of the aluminum layer of the composite material and the average thickness of the scaly graphite particle dispersion layer were calculated by the same method as in Example 1, the average thickness of the aluminum layer was 16 μm, and the scaly graphite particle dispersion layer had an average thickness of 16 μm. The average thickness was 33 μm. Therefore, X was 2.1.

Further, when a bending test piece having the same dimensions and shape as in Example 1 was cut out from the composite material and the test piece was bent under the same bending conditions as in Example 1, the aluminum layer and scaly graphite particles of the test piece were obtained. Systematic peeling and fracture were observed for the dispersed layer.

<Comparative example 3>
The same scaly graphite particles as those used in Example 1 were prepared. Also, an aluminum paste was prepared. The aluminum paste was a scaly aluminum powder to which mineral spirit and fatty acid were added, and the solid content of aluminum was 70% by mass.

Next, 61 g of scaly graphite particles, 160 g of aluminum paste, and 100 g of 10% polystyrene-cumene solution were mixed, kneaded, and dispersed to form a paste. Then, this paste-like product was sheet-molded on a PET sheet by the doctor blade method, and then air-dried for one day. Then, the PET sheet was peeled off to produce a green sheet of aluminum powder-scaly graphite particles. The thickness of the green sheet was 1 mm.

Next, a plurality of sheet pieces having the same dimensions and shape as in Example 1 were cut out from the green sheet. Then, a laminated body was formed by laminating 10 sheet pieces.

Next, the laminate was sintered under the same sintering apparatus and sintering conditions as in Example 1 to obtain an aluminum-scaly graphite particle composite material. The thickness of the composite material was 1 mm. The volume content of the scaly graphite particles in the composite material was 40% by volume with respect to the volume of the composite material.

In the composite material, aluminum as a metal matrix has sufficiently penetrated between the scaly graphite particles, there are almost no voids inside the composite material, and the density of the composite material is 99% of the theoretical density of the composite material. The sintered state of the composite material was good.

The thermal conductivity of the composite material in the plane direction was 440 W / (m · K), which was higher than the thermal conductivity of aluminum. In this composite material, the plane direction of the composite material means a direction perpendicular to the direction in which the laminated body is pressed during sintering of the laminated body.

Further, in the composite material, scaly graphite particles oriented in the plane direction of the composite material are three-dimensionally and randomly dispersed in aluminum as a metal matrix, and the average thickness of the aluminum layer and the scaly graphite particle dispersion layer are dispersed. It was not possible to define the average thickness of each.

Further, when a bending test piece having the same dimensions and shape as in Example 1 was cut out from the composite material and the test piece was bent under the same bending conditions as in Example 1, the aluminum matrix structure and aluminum / scaly graphite were obtained. Systematic peeling and breakage were observed at the particle interface.

The above results are summarized in Table 1.

The meanings of the symbols in the "evaluation of bending test" column in the same table are as follows.

◯: Good ×: Defective (broken)

The present invention can be used for a metal-carbon particle composite material in which scaly graphite particles as carbon particles are dispersed in a metal matrix.

1: Scale-like graphite particles 2: Binder 3: Solvent 5: Coating liquid 10: Metal leaf 10A: Metal leaf strip 11: Scale-like graphite particle layer 12: Coating foil 12A: Coating foil strip 15: Laminated body 20: Metal-carbon particle composite material Composite material 21: Scale-like graphite particle dispersion layer 22: Metal layer 23: Metal matrix 30: Coating apparatus

Claims (2)

A metal layer made of a metal matrix and a scaly graphite particle dispersion layer in which scaly graphite particles are dispersed in the metal matrix are joined and integrated in a state of being alternately laminated.
The average thickness of the metal layer is in the range of 16 to 100 μm.
The average thickness of the scaly graphite particle dispersion layer is in the range of 4 to 100 μm.
A metal-carbon particle composite material in which X is in the range of 0.1 9 to 1, where the ratio of the average thickness of the metal layer to the average thickness of the scaly graphite particle dispersion layer is 1: X. The metal-carbon particle composite according to claim 1, wherein the metal matrix is aluminum or copper.

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