JP2015025158A - Composite material of metal and carbon fiber and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite material of metal and carbon fiber with an outside surface having high mechanical strength.SOLUTION: There is provided a composite material 1A in which a plurality of metal layers 2 and carbon fiber layers 3 are alternately laminated in such a way that metal layers 2a and 2b are arranged at laminated-direction outermost sides, respectively, and these layers are unified by diffusion bonding. The thickness of each outermost metal layers 2a and 2b is set to be thicker than each inside metal layer 2c arranged between the outermost metal layer 2a and 2b.

Description

  The present invention relates to a composite material of metal and carbon fiber and a method for producing the same.

  In the present specification and claims, unless otherwise specified, the term “aluminum” is used to include an aluminum alloy, and the term “copper” is used to include a copper alloy.

  As a composite material of a metal and carbon fiber, for example, as described in Patent Document 1 (Patent No. 5150905) and Patent Document 2 (Patent No. 5145591), metal layers and carbon fiber layers are alternately formed. A plurality of laminated and united joints are known. This type of composite material is expected to be used as a material for members that require high heat conduction characteristics.

Japanese Patent No. 5150905 Japanese Patent No. 5145591

  In this type of composite material, each metal layer on both sides of the carbon fiber layer is mainly diffused through the carbon fiber layer and thermally diffused into the other metal layer, thereby joining the two metal layers together. By doing so, all the metal layers and the carbon fiber layers are integrated. Therefore, it is desirable that the carbon fiber layer is as thin as possible in terms of increasing bonding strength.

  In addition, when this type of composite material is used as a constituent layer of a heat-dissipating insulating substrate that releases heat from a semiconductor element such as an IC, the difference in linear expansion coefficient between the composite material and the ceramic layer included in the insulating substrate In order to prevent the occurrence of cracking or peeling due to thermal stress caused by the composite material, it is desirable that the linear expansion coefficient of the composite material be as small as possible. Here, generally, the linear expansion coefficient of carbon fiber is smaller than the linear expansion coefficient of metal. Therefore, it is desirable that the carbon fiber content in the composite (eg, the volume content of carbon fiber) be as large as possible because the linear expansion coefficient of the composite can be reduced.

  In addition, the thermal conductivity of carbon fibers is generally higher than that of metals. Therefore, it is desirable that the carbon fiber content in the composite material is as large as possible in terms of increasing the thermal conductivity of the composite material (that is, improving the heat dissipation characteristics).

  Therefore, in order to increase the bonding strength, reduce the linear expansion coefficient of the composite material, and further increase the thermal conductivity of the composite material, it is desirable to make the carbon fiber layer as thin as possible and increase the carbon fiber content as much as possible. In order to do this, it is preferable that both the metal layer and the carbon fiber layer are thinned and laminated.

  However, the following problems occur when the metal layer is made thin.

  That is, when the thin metal layer is disposed on the outermost side of the composite material, the mechanical strength of the outer surface of the composite material decreases. As a result, when the outer surface of the composite material is scratched, a surface defect occurs in which the carbon fiber is exposed from the scratch and the metal layer is easily peeled off from the scratch. In addition, the thickness of the metal layer disposed on the outermost side in the stacking direction of the composite material approaches the diameter dimension of the carbon fiber, and the outermost metal layer is distorted so as to correspond to the shape of the carbon fiber. The outer surface of the composite material is very easily damaged and the surface defects described above are more likely to occur.

  The present invention has been made in view of the above-described technical background, and the object thereof is a composite material of metal and carbon fiber, which has high thermal conductivity and a small linear expansion coefficient, and has high mechanical strength on the outer surface. It is in providing the manufacturing method.

  The present invention provides the following means.

[1] A plurality of metal layers and carbon fiber layers are alternately laminated in such a manner that metal layers are arranged on both outermost sides in the lamination direction, and these layers are joined and integrated by diffusion bonding. Yes,
The metal and carbon fiber composite material, wherein a thickness of the outermost metal layer is set to be greater than a thickness of an inner metal layer disposed between the outermost metal layers.

[2] The metal layer is made of aluminum,
The inner metal layer has a thickness of 20 μm or less,
2. The metal / carbon fiber composite material according to item 1, wherein the outermost metal layer has a thickness of 30 μm or more.

[3] The metal layer is made of copper,
The inner metal layer has a thickness of 15 μm or less,
2. The metal / carbon fiber composite material according to item 1, wherein the outermost metal layer has a thickness of 20 μm or more.

[4] A mixture adhering step of obtaining a preform foil in which a mixture layer is formed on a metal foil by adhering a mixture in which carbon fibers are mixed with a binder and a solvent in a layered manner on the metal foil;
A metal in which the preform foil or the mixture layer is not formed such that a plurality of the preform foils are laminated to form a preform foil laminate, and the metal foils are respectively disposed on both outermost sides in the lamination direction. Laminate forming step of laminating a foil with respect to at least one surface in the laminating direction of the preform foil laminate to form a final laminate of a metal foil and a mixture layer;
A step of bonding and integrating the final laminate by diffusion bonding at a temperature lower than the melting temperature of the metal foil in a non-oxidizing atmosphere or vacuum, and
In the laminate forming step, the thickness of the outermost metal foil disposed adjacent to the mixture layer of the preform foil in the final laminate is an inner metal foil disposed between both outermost metal foils. A method for producing a composite material of metal and carbon fiber, characterized in that it is set to be thicker than the thickness of the metal.

[5] The metal foil is an aluminum foil,
The inner metal foil has a thickness of 20 μm or less,
The thickness of the outermost metal foil disposed adjacent to the mixture layer of the preform foil is 30 μm or more,
When the outermost metal foil is disposed adjacent to the metal foil of the preform foil in the final laminate, the thickness of the outermost metal foil is the total thickness of the adjacent metal foils The manufacturing method of the composite material of the metal and carbon fiber of the preceding clause 4 set so that thickness may become 30 micrometers or more.

[6] The metal foil is a copper foil,
The inner metal foil has a thickness of 15 μm or less,
The thickness of the outermost metal foil disposed adjacent to the mixture of the preform foils in the final laminate is 20 μm or more,
When the outermost metal foil is disposed adjacent to the metal foil of the preform foil in the final laminate, the thickness of the outermost metal foil is the total thickness of the adjacent metal foils The manufacturing method of the composite material of the metal and carbon fiber of the preceding clause 4 set so that may become 20 micrometers or more.

  [7] The metal and carbon fiber composite material according to any one of [4] to [6], further including a drying step of drying the mixture layer of the preform foil before the laminate forming step. Production method.

  The present invention has the following effects.

  The composite material of the preceding item [1] has a structure in which a plurality of metal layers and carbon fiber layers are alternately laminated. Thereby, the heat conductivity of a composite material can be made high and the linear expansion coefficient of a composite material can be made small. Furthermore, since the thickness of the outermost metal layer is set to be greater than the thickness of the inner metal layer, the mechanical strength of the outer surface in the stacking direction of the composite material is high, and therefore the occurrence of surface defects can be prevented.

  In the preceding item [2], it is possible to provide a composite material of aluminum and carbon fiber that can surely exhibit the above-described effect of the composite material of the preceding item [1].

  In the preceding item [3], it is possible to provide a composite material of copper and carbon fiber that can surely exhibit the above-described effect of the composite material of the preceding item [1].

  In the manufacturing method of the composite material of the preceding item [4], the composite material of the preceding item [1] can be manufactured reliably. Further, in the joining step, the final laminate is joined and integrated by diffusion joining at a temperature lower than the melting temperature of the metal foil in a non-oxidizing atmosphere or in vacuum, thereby causing a chemical reaction between the metal of the metal foil and the carbon fiber. Formation of metal carbide can be prevented. Thereby, the characteristic change of the composite material accompanying the production | generation of a metal carbide can be prevented.

In the preceding item [5], the composite material of the preceding item [2] can be reliably manufactured. Furthermore, generation of aluminum carbide (Al ₄ C ₃ ) as a metal carbide can be prevented. Here, aluminum carbide reacts with water and moisture in the air to produce hydrocarbon gas (eg, methane gas) or changes to metal oxide, so the formation of aluminum carbide is the cause of internal defects in the composite material It becomes. Therefore, it is desirable that aluminum carbide is not generated as much as possible. However, in the preceding item [5], since the formation of aluminum carbide is prevented as described above, it is possible to obtain a composite material in which internal defects due to the formation of aluminum carbide do not occur,
In the preceding item [6], the composite material of the preceding item [3] can be reliably manufactured.

  In the preceding item [7], the composite material can be joined and integrated more firmly.

FIG. 1 is a cross-sectional view of a composite material of metal and carbon fiber according to the first embodiment of the present invention. FIG. 2A is a block diagram showing a manufacturing process of the composite material. FIG. 2B is a schematic view illustrating the manufacturing process of the composite material. FIG. 3 is a cross-sectional view showing a state in the middle of forming the final laminate for obtaining the composite material. FIG. 4 is a cross-sectional view showing a state in the middle of joining and integrating the final laminate by a discharge plasma sintering method. FIG. 5 is a cross-sectional view of a composite material of metal and carbon fiber according to the second embodiment of the present invention. FIG. 6 is a cross-sectional view showing a state in the middle of forming the final laminate for obtaining the composite material. FIG. 7 is a cross-sectional view of a composite material of metal and carbon fiber according to the third embodiment of the present invention. FIG. 8 is a cross-sectional view showing a state in the middle of forming the final laminate for obtaining the composite material. FIG. 9 is a cross-sectional view of a composite material of metal and carbon fiber according to the fourth embodiment of the present invention. FIG. 10 is a cross-sectional view showing a state in the middle of forming the final laminate for obtaining the composite material.

  Next, several embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, in the composite material 1A of metal and carbon fiber according to the first embodiment of the present invention, the metal layers 2a and the carbon fiber layers 3 are alternately arranged on the outermost sides in the laminating direction, respectively. A plurality of layers 2b are laminated in such a manner that 2b is arranged, and these layers 2 and 3 are joined and integrated by diffusion bonding. In the drawing, the carbon fiber layer 3 is shown by dot hatching to distinguish it from the metal layer 2.

  Here, in the composite material 1A of the first embodiment, the stacking direction is set to the vertical direction for convenience of explanation. Furthermore, the thickness direction of the composite material 1A is set to the stacking direction. However, the present invention is not limited to setting the stacking direction in the vertical direction, and can be set in any direction such as the front-rear direction and the left-right direction.

  Furthermore, in the composite material 1A of the first embodiment, the metal layer 2 disposed on the uppermost side as one of the outermost sides in the stacking direction (that is, the vertical direction) of all the metal layers 2 is particularly “the uppermost metal. The layer 2a "and the metal layer 2 disposed on the lowermost side as the other side are particularly referred to as the" lowermost metal layer 2b ", and further disposed between the uppermost metal layer 2a and the lowermost metal layer 2b. The formed metal layer 2 is particularly referred to as “inner metal layer 2c”.

  The composite material 1A has a length of, for example, 10 to 300 mm, a width of, for example, 10 to 200 mm, and a thickness (that is, a thickness in the stacking direction) of, for example, 0.5 to 20 mm. However, in the present invention, the size (length, width, thickness) of the composite material 1A is not limited to be set within such a range, and may vary depending on the use of the composite material 1A. Is set.

  In this composite material 1A, the respective metal layers 2 and 2 on both sides of the carbon fiber layer 3 pass through the carbon fiber layer 3 and thermally diffuse into the opposite metal layer 2, whereby both metal layers 2 As a result, all the metal layers 2 and the carbon fiber layers 3 are integrated.

  The metal forming the metal layer 2 is not limited, but is particularly preferably aluminum or copper. By doing so, the thermal conductivity of the composite material 1A can be reliably increased.

  In the first embodiment, all the metal layers 2 are formed of the same kind of metal, and specifically, it will be described below as being formed of aluminum or copper.

  The carbon fibers 40 (see FIG. 2B) forming the carbon fiber layer 3 are PAN-based carbon fibers, pitch-based carbon fibers, and carbon nanotubes (for example, vapor-grown carbon nanofibers, single-wall carbon nanofibers, multi-wall carbon nanotubes). Or a short carbon fiber having a fiber length of 0.1 nm to 20 μm and a fiber length of 0.5 μm to 1.0 mm selected from the group consisting of 2) or more, and a fiber length of 0.1 nm to 20 μm and a fiber length. A mixed short carbon fiber of 0.5 μm to 1.0 mm is desirable. In particular, the PAN-based carbon fiber and the pitch-based carbon fiber are preferably chopped fibers or milled fibers having a fiber diameter of 5 to 15 μm and a fiber length of 50 μm to 1 mm. Desirably, the fiber diameter is 0.1 nm to 20 μm and the fiber length is 0.5 μm to 1 mm. By doing so, the mixture 45 in which the carbon fiber is mixed with the binder 41 and the solvent 42 can be reliably liquefied. it can.

  In the carbon fiber layer 3, the carbon fibers 40 are arranged in a state of being oriented in a direction perpendicular to the stacking direction (that is, a plane direction).

  Here, the carbon fiber layer 3 is formed mainly of the carbon fibers 40. Specifically, the carbon fiber layer 3 may be formed of only the carbon fibers 40, or may be formed of the carbon fibers 40 and a binder 41 described later, or a dry residue of the binder 41 and carbon. It may be formed with the fiber 40, or may be formed with the combustion residue of the binder 41 and the carbon fiber 40. Furthermore, the carbon fiber layer 3 may be formed of only the carbon fibers 40 left by drying or burning the binder 41.

  The composite material 1A of the first embodiment has a structure in which a plurality of metal layers 2 and carbon fiber layers 3 are alternately stacked. Thereby, the linear expansion coefficient of the composite material 1A is small, and the thermal conductivity of the composite material 1A is high. Furthermore, the thickness of the uppermost metal layer 2a and the lowermost metal layer 2b is set to be thicker than the thickness of each inner metal layer 2c. As a result, the mechanical strength of the upper surface 1a and the lower surface 1b of the composite material 1A (that is, both outer surfaces in the stacking direction of the composite material 1A) is increased, and therefore surface defects (carbon) caused by scratching the upper and lower surfaces 1a, 1b. Generation of the fiber layer 3 exposure, peeling of the outermost gold layer layers 2a and 2b, etc.) can be prevented. Moreover, since only the uppermost metal layer 2a and the lowermost metal layer 2b are thick, an increase in the linear expansion coefficient and a decrease in thermal conductivity of the composite material 1A can be suppressed as much as possible.

  A desirable thickness of the metal layer 2 is as follows.

  When the metal layer 2 is made of aluminum, the thickness of each inner metal layer 2c is 20 μm or less, and the thicknesses of the uppermost metal layer 2a and the lowermost metal layer 2b are each 30 μm or more (particularly desirably 50 μm). As described above, it is desirable to prevent the occurrence of surface defects in a state where the linear expansion coefficient of the composite material 1A is small and the thermal conductivity is increased. The lower limit of the thickness of each inner metal layer 2c is not limited, but is preferably 10 μm, and by doing so, the metal layers 2 and 2 on both sides sandwiching the carbon fiber layer 3 are firmly formed. It is possible to join by diffusion joining, and the joining strength can be reliably increased. The upper limit of the thickness of the uppermost metal layer 2a and the lowermost metal layer 2b is not limited, and is set to 10 mm, for example.

  As the aluminum forming the metal layer 2, any aluminum that can be used as a foil can be used. For example, pure aluminum, JIS (Japanese Industrial Standard) alloy symbols A1000, A3000, and A8000 series aluminum are preferably used. It is done.

  When the metal layer 2 is made of copper, the thickness of each inner metal layer 2c is 15 μm or less, and the thicknesses of the uppermost metal layer 2a and the lowermost metal layer 2b are each 20 μm or more (particularly desirably 30 μm). As described above, it is desirable to prevent the occurrence of surface defects in a state where the linear expansion coefficient of the composite material 1A is small and the thermal conductivity is increased. The lower limit of the thickness of each inner metal layer 2c is not limited, but is particularly preferably 6 μm, and by doing so, the metal layers 2 and 2 on both sides sandwiching the carbon fiber layer 3 are strengthened. It is possible to join by diffusion joining, and the joining strength can be reliably increased. The upper limit of the thickness of the uppermost metal layer 2a and the lowermost metal layer 2b is not limited, and is set to 10 mm, for example.

  As copper forming the metal layer 2, rolled copper, electrolytic copper, or the like is used. That is, the metal layer 2 is formed from a rolled copper foil or an electrolytic copper foil.

  Regarding the volume content of the carbon fibers 40 excluding the uppermost metal layer 2a and the lowermost metal layer 2b in the composite material 1A (hereinafter, simply referred to as “carbon fiber volume content Vf”), It is set in various ways depending on the type and use of the composite material 1A, and it is particularly preferable to set it in the range of 30 to 50% by volume. By setting the volume content Vf of carbon fiber and the thickness of the carbon fiber layer 3 in this way, the bonding strength can be reliably increased and the linear expansion coefficient of the composite material 1A can be reliably reduced. The thermal conductivity of the composite material 1A can be reliably increased.

  The number of the inner metal layers 2c and the number of the carbon fiber layers 3 in the composite material 1A are not limited respectively, and are variously set according to the use of the composite material 1A. The number of the inner metal layers 2c is The number of carbon fiber layers 3 may be one or more and two or more. Further, the upper limit of the number of inner metal layers 2c and the upper limit of the number of carbon fiber layers 3 are not limited respectively, and may be, for example, several thousand layers (example: 3000 layers).

  In this composite material 1 </ b> A, each inner metal layer 2 c is a layer formed from one metal foil 12. Of the outermost metal layers 2a and 2b, the uppermost metal layer 2a is a layer formed from one metal foil 12a, while the lowermost metal layer 2b is a plurality of two sheets laminated together. This is a layer formed by joining and integrating the metal foils 12 and 12b by diffusion bonding.

  Next, the manufacturing method of 1 A of composite materials of this 1st Embodiment is demonstrated below with reference to FIG.

  As shown in FIG. 2A, the manufacturing method of the composite material 1A of the first embodiment includes a mixture adhering step S1, a drying step S2, a laminate forming step S3, a joining step S4, and the like.

  As shown in FIG. 2B, the mixture adhering step S <b> 1 is performed on at least one surface of both surfaces of the metal foil 12 with the mixture 45 as a coating liquid obtained by mixing the carbon fibers 40 with the binder 41 and the solvent 42 on the metal foil 12. This is a step of obtaining a preform foil 20 in which the mixture layer 13 is formed on at least one surface of the metal foil 12 by being attached in layers. In the first embodiment, the mixture 45 is deposited on the upper surface as one side of the metal foil 12 in a layered manner over substantially the entire surface thereof, so that the preform foil 20 is disposed on the substantially upper surface of the metal foil 12. The mixture layer 13 is formed over the entire area.

  Here, when the metal layer 2 of the composite material 1 </ b> A is formed of aluminum, an aluminum foil is used as the metal foil 12. When the metal layer 2 of the composite material 1 </ b> A is formed of copper, a copper foil is used as the metal foil 12. A desirable thickness of the metal foil 12 will be described later.

  As the binder 41, a resin such as polyethylene oxide (polyethylene glycol, polyoxyethylene) or acrylic is preferably used. Examples of the solvent 42 include water, alcohol (eg, methanol), glycol solvent (eg, ethylene glycol, diethylene glycol, propylene glycol, ethylene glycol ethers (cellosolve), acetates, diethylene glycol ethers, acetates, propylene. Glycol ethers, acetates) and the like.

  As shown in FIG. 2B, in the mixture adhering step S1, the carbon fiber 40, the binder 41, and the solvent 42 are put in a mixing container 49, and these are stirred and mixed by a stirrer (example: mixer) 48. A mixture 45 containing 40 is obtained as a coating liquid. At this time, not only the carbon fiber 40 but also metal particles of the same kind as the metal of the metal foil 12 (metal layer 2) (its particle size: 1 to 150 μm) may be mixed. Further, a dispersant for adjusting the mixture (paint liquid) 45, a surface conditioner, a thickener, and the like may be mixed.

Next, the mixture 45 is adhered (applied) on the upper surface of the metal foil 12 in a layered manner over the substantially entire surface using the coating apparatus 50. Although the adhesion amount of the mixture 45 is not limited, it is desirable to set it so that it will be in the range of 20-50 g / m < ² > in the state after drying the mixture 45 by drying process S2 mentioned later. .

  As the coating apparatus 50, a roll coater, a gravure coater or the like is used. In the coating apparatus 50 shown in FIG. 2B, the strip 12 </ b> A of the metal foil 12 unwound from the unwinding roll 51 sequentially passes through the application roll unit 52 and the drying furnace 55 and is wound up by the winding roll 53. Adhesion of the mixture 45 is performed by the application roll unit 52. That is, when the strip 12A of the metal foil 12 unwound from the unwinding roll 51 passes through the coating roll unit 52, the mixture 45 is adhered to the upper surface of the strip 12A by the coating roll unit 52, and the mixture layer 13 Is formed into the strip material 20A of the preform foil 20, and after passing through the drying furnace 55, it is wound up by the winding roll 53. The application roll unit 52 includes a mixture pan 52a, a pickup roll 52b, an applicator roll 52c, a backup roll 52d, and the like.

  The drying step S2 is a step of drying the mixture layer 13 of the preform foil 20. In the first embodiment, the mixture layer 13 is dried by the drying furnace 55 (eg, hot air drying furnace) of the coating apparatus 50 described above.

  The drying conditions of the mixture layer 13 are not limited as long as the solvent component contained in the mixture layer 13 can be removed from the mixture layer 13 by evaporation, and in particular, the drying temperature is 80 to 180 ° C. and the drying time is 1. The condition of -10 min is often applied. By this drying step S2, the solvent component in the mixture layer 13 of the preform foil 20 is removed by evaporation, and mainly the carbon fibers 40 remain in the mixture layer 13, that is, the mixture layer 13 becomes a layer mainly composed of carbon fibers. .

  The stacked body forming step S3 is a process of forming the final stacked body 30A of the metal foil 12 and the mixture layer 13. In this step S3, first, a plurality of preform foils 20 having a predetermined shape (for example, a square shape) are formed from the strip material 20A of the preform foil 20 that is dried in the drying step S2 and wound by the winding roll 53. cut. Then, a plurality of preform foils 20 are laminated in the vertical direction in the same direction as shown in FIG. 3 to form (manufacture) the preform foil laminate 25, and the metal foil 12 on which the mixture layer 13 is not formed is formed. The uppermost metal foil 12a and the lowermost metal foil 12b are laminated on the upper surface and the lower surface of the preform foil laminate 25, respectively. Thereby, the final laminated body 30A of the metal foil 12 and the mixture layer 13 is formed (manufactured). In the final laminate 30A, the metal foils 12 on which the mixture layer 13 is not formed are arranged on the uppermost side and the lowermost side in the vertical direction (that is, the laminating direction). The shapes and dimensions of the plurality of preform foils 20 stacked on each other are the same shape and the same size.

  Further, in this final laminate 30A, the uppermost metal foil 12a is arranged adjacent to the upper side of the mixture layer 13 of the preform foil 20, while the lowermost metal foil 12b is the metal of the preform foil 20. The foil 12 is disposed adjacent to the lower side thereof.

  In the joining step S4, the final laminated body 30A (specifically, all the foils forming the final laminated body 30A (that is, all the preform foils 20, the uppermost metal foil 12a, and the lowermost metal foil 12b)) are not removed. This is a step of bonding and integration by diffusion bonding at a bonding temperature lower than the melting temperature of the metal foil 12 (that is, the melting point of the metal foil 12) in an oxidizing atmosphere or vacuum. As the diffusion bonding, a discharge plasma sintering method (SPS method), a hot press method, a hot rolling roll method, or the like is used. In the first embodiment, a discharge plasma sintering method is used as diffusion bonding.

  A method of joining and integrating the final laminate 30A by the discharge plasma sintering method will be described below.

  As shown in FIG. 4, a discharge plasma sintering apparatus 60 including a cylindrical die 61 having conductivity and a pair of punches 62 and 62 having conductivity is prepared. An electrode 63 is electrically connected to each punch 62. The final laminated body 30A is arranged in the die 61, and the punches 62 are arranged on both sides in the lamination direction of the final laminated body 30A. Then, in the non-oxidizing atmosphere such as an inert gas (eg, nitrogen gas, argon gas) atmosphere or vacuum (degree of vacuum: 1 to 30 Pa), the final laminate 30A is applied in the stacking direction by both punches 62 and 62. By applying a pulse current between the punches 62 and 62 while pressing, the final laminate 30A (specifically, all the foils forming the final laminate 30A (that is, all the preform foils 20, the uppermost metal foil). 12a and the lowermost metal foil 12b)) are joined and integrated. Thus, the desired composite material 1A shown in FIG. 1 is obtained.

  Preferred joining conditions by the discharge plasma sintering method are as follows.

  When the metal foil 12 is an aluminum foil, the bonding temperature is 450 to 600 ° C., the bonding time (that is, the holding time of the bonding temperature) is 10 to 300 min, and the applied pressure to the final laminate 30A is 10 to 40 MPa. It is good to set. When the metal foil 12 is a copper foil, the bonding temperature is set to 800 to 1000 ° C., the holding time of the bonding temperature is set to 10 to 300 min, and the pressure applied to the final laminate 30A is set to a range of 10 to 40 MPa. good.

  In this bonding step S4, the carbon fiber layer 3 is formed from the mixture layer 13, and the metal layers 2 and 2 are formed from the metal foils 12 and 12 on both sides of the mixture layer 13, respectively. 2 (both metal foils 12, 12) pass through the carbon fiber layer 3 (mixture layer 13) by heat at the time of bonding and thermally diffuse into the partner metal layer 2 (metal foil 12), Both metal layers 2 and 2 (both metal foils 12 and 12) are joined. Further, the lowermost metal foil 12b and the metal foil 12 of the preform foil 20 adjacent thereto are directly joined and integrated to form one lowermost metal layer 2b.

  As described above, in the carbon fiber layer 3, the binder 41, a dry residue of the binder 41, a combustion residue of the binder 41, or the like may remain, or by drying or burning the binder 41. It may be completely removed and only the carbon fiber 40 may remain.

  In the manufacturing method of the composite material 1A described above, in the laminated body forming step S3, a plurality of preform foils 20 are laminated and disposed between the uppermost metal foil 12a and the lowermost metal foil 12b. When the metal foil 12 of the preform foil 20 is an aluminum foil, the thickness of the aluminum foil is desirably 20 μm or less for the reasons described above, and the lower limit of the thickness is desirably 10 μm. When the metal foil 12 of the preform foil 20 is a copper foil, the thickness of the copper foil is desirably 15 μm or less for the reasons described above, and the lower limit of the thickness is desirably 6 μm.

  Of the uppermost metal foil 12a and the lowermost metal foil 12b, the thickness of the uppermost metal foil 12a disposed adjacent to the mixture layer 13 of the preform foil 20 is greater than the thickness of the metal foil 12 of the preform foil 20. It is also set thick.

  When the metal foil 12 is an aluminum foil, the thickness of the uppermost metal foil 12a is desirably 30 μm or more (particularly desirably 50 μm or more) for the reason described above. The upper limit of the thickness of the uppermost metal foil 12a is not limited, and is set to 10 mm, for example. On the other hand, when the uppermost metal foil 12a is a copper foil, the thickness of the uppermost metal foil 12a is desirably 20 μm or more (particularly desirably 30 μm or more) for the reason described above. The upper limit of the thickness of the uppermost metal foil 12a is not limited, and is set to 10 mm, for example.

  Of the uppermost metal foil 12a and the lowermost metal foil 12b, the lowermost metal foil 12b disposed adjacent to the metal foil 12 of the preform foil 20 is adjacent to the lowermost metal foil 12b as described above. Thus, the lowermost metal layer 2b is formed by joining and integrating with the metal foil 12 arranged as described above, and as a result, the thickness of the metal foil 12 of the preform foil 20 (ie, the inner metal foil 12c) is reduced. Thicker than the thickness. Therefore, the lower limit of the thickness of the lowermost metal foil 12b for making the thickness of the lowermost metal layer 2b thicker than the thickness of the inner metal layer 2c is not limited. However, when the metal foil 12 is an aluminum foil, for the reasons described above, the thickness of the lowermost metal foil 12b is equal to the thickness of the lowermost metal foil 12b (ie, the inner metal foil 12c). It is desirable that the total thickness of the first and second layers is set to be 30 μm or more (particularly desirably 50 μm or more). That is, for example, when the thickness of the metal foil 12 (inner metal foil 12c) adjacent to the lowermost metal foil 12b is 10 μm, the thickness of the lowermost metal foil 12b is 20 μm or more (particularly desirably 40 μm or more). It is desirable that On the other hand, when the metal foil 12 is a copper foil, for the reasons described above, the thickness of the lowermost metal foil 12b is equal to the thickness of the lowermost metal foil 12b (that is, the inner metal foil 12c). It is desirable that the total thickness is set to 20 μm or more (particularly desirably 30 μm or more). That is, for example, when the thickness of the metal foil 12 (inner metal foil 12c) adjacent to the lowermost metal foil 12b is 6 μm, the thickness of the lowermost metal foil 12b is 14 μm or more (particularly desirably 24 μm or more). It is desirable that

According to the method of manufacturing the composite material 1A of the first embodiment, in the joining step S4, the final laminate 30A is joined and integrated by diffusion joining at a temperature lower than the melting temperature of the metal foil 12 in a non-oxidizing atmosphere or vacuum. Therefore, generation of metal carbide due to a chemical reaction between the metal of the metal foil 12 and the carbon fiber 40 can be prevented. Thereby, the characteristic change of 1 A of composite materials accompanying the production | generation of a metal carbide can be prevented. In particular, when the metal foil 12 is an aluminum foil, the production of aluminum carbide (Al ₄ C ₃ ) as a metal carbide can be prevented. For this reason, it is possible to obtain a composite material 1A in which internal defects due to the formation of aluminum carbide do not occur, thereby maintaining the mechanical strength and thermal conductivity of the composite material 1A in a good state.

  Furthermore, since the mixture layer 13 is dried in the drying step S2 and the liquid components in the mixture layer 13 are removed, the final laminate 30A can be joined and integrated more firmly in the joining step S4.

  5 and 6 are diagrams for explaining a composite material 1B of metal and carbon fiber according to the second embodiment of the present invention. In the following, the second embodiment will be described focusing on the differences from the first embodiment.

  In the method for manufacturing the composite material 1B according to the second embodiment, as shown in FIG. 6, among the plurality of preform foils 20 in which the mixture layer 13 is formed on the metal foil 12, the preform disposed on the lowermost side. The thickness of the metal foil 12 of the reform foil 20 is thicker than the thickness of the metal foil 12 of the other preform foils 20. This preform foil 20 is particularly referred to as “thick preform foil 20b” for convenience of explanation. The metal foil 12 of the thick preform foil 20b corresponds to the lowermost metal foil 12b.

  In the laminate forming step S3, a plurality of preform foils 20 are laminated to form a preform foil laminate 25, and the metal foil 12 on which the mixture layer 13 is not formed is used as the uppermost metal foil 12a. 25, and the thick preform foil 20b is laminated on the lower surface of the preform foil laminate 25 so that the metal foil 12 of the thick preform foil 20b is disposed on the lowermost side. To do. Thereby, the final laminated body 30B of the metal foil 12 and the mixture layer 13 is formed. In the final laminate 30B, the metal foil 12 without the mixture layer 13 is disposed on the uppermost side in the vertical direction (that is, the laminating direction), while the thick preform foil 20b is disposed on the lowermost side. The metal foil 12 is arranged as the lowermost metal foil 12b.

  Next, in the bonding step S4, the final laminated body 30B (specifically, all the foils forming the final laminated body 30B (that is, all the preform foils 20, 20b, the uppermost metal foil 12a)) are treated in a non-oxidizing atmosphere or Bonding and integration are performed by diffusion bonding at a temperature lower than the melting temperature of the metal foil 12 in a vacuum.

  Other configurations in the second embodiment are the same as those in the first embodiment.

  Here, in the composite material 1A of the first embodiment, as described above, the lowermost metal layer 2b is directly formed by the lowermost metal foil 12b and the metal foil 12 of the preform foil 20 adjacent thereto. Are integrally formed with each other (see FIG. 1). On the other hand, in the composite material 1B of the second embodiment, the lowermost metal layer 2b is formed only of the metal foil 12 of the thick preform foil 20b (see FIG. 5).

  7 and 8 are views for explaining a composite material 1C of metal and carbon fiber according to the third embodiment of the present invention. In the following, the third embodiment will be described focusing on differences from the first and second embodiments.

  As shown in FIG. 7, the composite material 1 </ b> C of the third embodiment includes three metal layers 2 (the breakdown: two outermost metal layers 2 a and 2 b and one inner metal layer 2 c) and two layers. The carbon fiber layer 3 is formed. And the inner metal layer 2c is a layer formed from one metal foil 12, like the composite material 1A of the first embodiment. Of the outermost metal layers 2a and 2b, the uppermost metal layer 2a is a layer formed from one metal foil 12a, while the lowermost metal layer 2b is adjacent to the lowermost metal foil 12b. The preform foil 20 is formed by directly joining and integrating the metal foil 12 (see FIG. 8).

  As shown in FIG. 8, the composite material 1C of the third embodiment includes two preform foils 20 and a metal foil 12a as one uppermost metal foil 12a on which the mixture layer 13 is not formed. Using the metal foil 12b as the lowermost metal foil 12b on which the mixture layer 13 is not formed, it is manufactured by the same method as the method for manufacturing the composite material 1A of the first embodiment.

  9 and 10 are views for explaining a composite material 1D of metal and carbon fiber according to a fourth embodiment of the present invention. Hereinafter, the fourth embodiment will be described focusing on the differences from the first to third embodiments.

  As shown in FIG. 9, the composite material 1D of the fourth embodiment is composed of three metal layers 2 (breakdown: two outermost metal layers 2a, as in the composite material 1C of the third embodiment). 2b and one inner metal layer 2c) and two carbon fiber layers 3. And the inner metal layer 2c is a layer formed from one metal foil 12, like the composite material 1A of the second embodiment. Of the outermost metal layers 2a and 2b, the uppermost metal layer 2a is a layer formed from one metal foil 12a, while the lowermost metal layer 2b is only the metal foil 12 of the thick preform foil 20b. (See FIG. 10).

  In the laminated body forming step S3 in the manufacturing method of the composite material 1D of the fourth embodiment, as shown in FIG. 10, the two preform foils 20 and 20b are formed of the metal foil 12 of the thick preform foil 20b in the vertical direction. The preform foil laminate 25 is formed by being laminated so as to be arranged at the lowermost side (that is, the lamination direction), and the metal foil 12 on which the mixture layer 13 is not formed is used as the uppermost metal foil 12a. Lamination is performed on the upper surface of the laminate 25. Thereby, the final laminated body 30D of the metal foil 12 and the mixture layer 13 is formed. In this final laminated body 30D, the metal foil 12 on which the mixture layer 13 is not formed is disposed on the uppermost side in the vertical direction (that is, the laminating direction), while the thick preform foil 20b is disposed on the lowermost side. The metal foil 12 is arranged as the lowermost metal foil 12b.

  Next, in the bonding step S4, the final laminated body 30D (specifically, all the foils forming the final laminated body 30A (that is, all the preform foils 20, 20b and the uppermost metal foil 12a)) are treated in a non-oxidizing atmosphere or Bonding and integration are performed by diffusion bonding at a temperature lower than the melting temperature of the metal foil 12 in a vacuum.

  Other configurations in the fourth embodiment are the same as those in the first and second embodiments.

  As mentioned above, although several embodiment of this invention was described, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it can change variously.

  In the present invention, the outer surface of the outermost metal layer may be bonded with titanium, stainless steel, nickel or the like to improve the corrosion resistance of the outer surface, or the outer surface may be plated with zinc or the like. It may be improved.

  Next, specific examples and comparative examples of the present invention will be described below.

<Example>
1A of the first embodiment shown in FIG. 1 was manufactured by the following procedure.

  10 g of carbon fiber milled fiber (manufactured by Nippon Graphite Fiber Co., Ltd .: XN-100) as carbon fiber 40, 50 ml of methanol, and 0.2 g of polyvinyl acetamide (manufactured by Showa Denko KK: PNVA (registered trademark)) as a dispersant. The mixture was mixed and dispersed with a mixer to obtain a carbon fiber dispersion.

  In addition, 2 g of a mixed solution obtained by mixing polyoxyethylene (manufactured by Meisei Chemical Industry Co., Ltd .: Alcox (registered trademark) E-45) and the solvent 42 as the binder resin 41 at a mass ratio of 0.2: 1 The mixture was added to the fiber dispersion and mixed with stirring, whereby a mixture 45 as a coating liquid was obtained. As the solvent 42, a methanol-water (volume ratio 1: 1) solution was used.

Next, the mixture 45 is applied in a layered manner with a coating amount of 100 g / m ² on the upper surface of the strip 12A of aluminum foil (material: JIS alloy symbol A1N30) 12 having a thickness of 15 μm as a metal foil (application). Thus, a strip material 20A of the preform foil 20 in which the mixture layer 13 was formed on the upper surface of the aluminum foil 12 was obtained. The melting point of the aluminum foil 12 is 680 ° C. Then, the mixture layer 13 of the strip 20A of the preform foil 20 was dried under the conditions of a drying temperature of 100 ° C. and a drying time of 10 minutes. As a result, the amount of the mixture layer 13 after drying became about 20 g / m ² . .

  Next, a plurality of rectangular preform foils (its dimensions: 50 mm length and 50 mm width) 20 were cut out from the strip material 20A of the preform foil 20. Then, 80 preform foils 20 are stacked in the same direction to form a preform foil laminate 25, and a 30 μm thick aluminum foil (material: A1N30) 12 without the mixture layer 13 formed. Is laminated on the upper surface of the preform foil laminate 25 as the uppermost aluminum foil 12a, and the 15 μm thick aluminum foil (material: A1N30) 12 on which the mixture layer 13 is not formed is used as the lowermost aluminum foil 12b. Was laminated on the lower surface of the preform foil laminate 25. Thereby, the final laminated body 30A of the aluminum foil 12 and the mixture layer 13 was obtained.

  Then, the final laminate 30A (specifically, all the foils forming the final laminate 30A (that is, all the preform foils 12, the uppermost aluminum foil 12a, and the lowermost aluminum) are formed using the discharge plasma sintering apparatus 60. The foil 12b)) was joined and integrated in a vacuum by a discharge plasma sintering method, thereby producing a composite material 1A of metal and carbon fiber. The joining conditions at this time are a joining temperature of 550 ° C., a joining time of 3 hours, a pressure of 30 MPa applied to the final laminate 30A, and a degree of vacuum of 10 Pa.

The characteristics of the obtained composite material 1A are: specific gravity 2.54, thermal conductivity 300 W / (m · K) perpendicular to the stacking direction, and linear expansion coefficient 1.6 × 10 ⁻⁶ perpendicular to the stacking direction. / K.

  Then, in order to evaluate the mechanical strength of the obtained composite material 1A, the upper surface 1a of the composite material 1A was rubbed with a metal spatula. Did not occur. Therefore, it was confirmed that the mechanical strength of the upper surface 1a of the composite material 1A was high.

<Comparative example>
A plurality of preform foils 20 were cut out from the strip material 20A of the preform foil 20 manufactured by the same method as in the above example. Then, 80 preform foils 20 are stacked in the vertical direction in the same direction, and 15 μm thick aluminum foil (material: A1N30) 12 on which the mixture layer 13 is not formed is used as the uppermost aluminum foil 12a. Lamination was performed on the upper surface of the laminate 25, while no lamination was performed on the lower surface of the preform foil laminate 25. This obtained the final laminated body of aluminum foil and a mixture layer.

  Next, the final laminate was joined and integrated by the discharge plasma sintering method under the same joining conditions as in the above example, thereby producing a composite material of metal and carbon fiber.

The characteristics of the obtained composite material are: specific gravity 2.53, thermal conductivity 300 W / (m · K) in the direction perpendicular to the stacking direction, coefficient of linear expansion 1.6 × 10 ⁻⁶ / perpendicular to the stacking direction K.

  And in order to evaluate mechanical strength about the obtained composite material, when the upper surface of the composite material was rubbed with the metal spatula, the hole by a crack opened in the upper surface and carbon fiber exposed from this hole. Therefore, it was confirmed that the mechanical strength of the upper surface of the composite material was weak.

  INDUSTRIAL APPLICABILITY The present invention can be used for a composite material of metal and carbon fiber and a manufacturing method thereof.

1A to 1D: Composite material of metal and carbon fiber 2: Metal layer 2a: Uppermost metal layer (outermost metal layer)
2b: Lowermost metal layer (outermost metal layer)
2c: inner metal layer 3: carbon fiber layer 12: metal foil 12a: uppermost metal foil (outermost metal foil)
12b: Bottom metal foil (outermost metal foil)
13: Mixture layer 20: Preform foil 25: Preform foil laminate 30A to 30D: Final laminate 40 of metal foil and mixture layer 40: Carbon fiber 41: Binder 42: Solvent 45: Mixture 50: Coating device 60: Spark plasma sintering equipment

[6] The metal foil is a copper foil,
The inner metal foil has a thickness of 15 μm or less,
The thickness of the outermost metal foil disposed adjacent to the mixture layer of the preform foil in the final laminate is 20 μm or more,
When the outermost metal foil is disposed adjacent to the metal foil of the preform foil in the final laminate, the thickness of the outermost metal foil is the total thickness of the adjacent metal foils The manufacturing method of the composite material of the metal and carbon fiber of the preceding clause 4 set so that may become 20 micrometers or more.

The carbon fibers 40 (see FIG. 2B) forming the carbon fiber layer 3 are PAN-based carbon fibers, pitch-based carbon fibers, and carbon nanotubes (for example, vapor-grown carbon nanofibers, single-wall carbon nanofibers, multi-wall carbon nanotubes). Or a short carbon fiber having a fiber length of 0.1 nm to 20 μm and a fiber length of 0.5 μm to 1.0 mm selected from the group consisting of 2) or more, and a fiber length of 0.1 nm to 20 μm and a fiber length. A mixed short carbon fiber of 0.5 μm to 1.0 mm is desirable. In particular, the PAN-based carbon fiber and the pitch-based carbon fiber are preferably chopped fibers or milled fibers having a fiber diameter of 5 to 15 μm and a fiber length of 50 μm to 1 mm. Desirably, the fiber diameter is 0.1 nm to 20 μm and the fiber length is 0.5 μm to 1 mm. By doing this, the mixture 45 in which the carbon fiber 40 is mixed with the binder 41 and the solvent 42 is surely liquefied. Can do.

When the metal foil 12 is an aluminum foil, the bonding temperature is 450 to 600 ° C., the bonding time (that is, the holding time of the bonding temperature) is 10 to 300 min, and the pressure applied to the final laminate 30A is 10 to 40 MPa. It is good to set. When the metal foil 12 is a copper foil, the bonding temperature is set to 800 to 1000 ° C., the holding time of the bonding temperature is set to 10 to 300 min, and the pressure applied to the final laminate 30A is set to a range of 10 to 40 MPa. good.

Claims (7)

A plurality of metal layers and carbon fiber layers are alternately laminated in such a manner that the metal layers are arranged on both outermost sides in the lamination direction, and these layers are joined and integrated by diffusion bonding,
The metal and carbon fiber composite material, wherein a thickness of the outermost metal layer is set to be greater than a thickness of an inner metal layer disposed between the outermost metal layers. The metal layer is formed of aluminum;
The inner metal layer has a thickness of 20 μm or less,
The metal / carbon fiber composite material according to claim 1, wherein the outermost metal layer has a thickness of 30 μm or more. The metal layer is formed of copper;
The inner metal layer has a thickness of 15 μm or less,
The composite material of metal and carbon fiber according to claim 1, wherein the outermost metal layer has a thickness of 20 μm or more. A mixture adhering step of obtaining a preform foil in which a mixture layer is formed on a metal foil by adhering a mixture in which carbon fibers are mixed with a binder and a solvent in a layer form on the metal foil;
A metal in which the preform foil or the mixture layer is not formed such that a plurality of the preform foils are laminated to form a preform foil laminate, and the metal foils are respectively disposed on both outermost sides in the lamination direction. Laminate forming step of laminating a foil with respect to at least one surface in the laminating direction of the preform foil laminate to form a final laminate of a metal foil and a mixture layer;
A step of bonding and integrating the final laminate by diffusion bonding at a temperature lower than the melting temperature of the metal foil in a non-oxidizing atmosphere or vacuum, and
In the laminate forming step, the thickness of the outermost metal foil disposed adjacent to the mixture layer of the preform foil in the final laminate is an inner metal foil disposed between both outermost metal foils. A method for producing a composite material of metal and carbon fiber, characterized in that it is set to be thicker than the thickness of the metal. The metal foil is an aluminum foil,
The inner metal foil has a thickness of 20 μm or less,
The thickness of the outermost metal foil disposed adjacent to the mixture layer of the preform foil in the final laminate is 30 μm or more,
When the outermost metal foil is disposed adjacent to the metal foil of the preform foil in the final laminate, the thickness of the outermost metal foil is the total thickness of the adjacent metal foils The method for producing a composite material of metal and carbon fiber according to claim 4, wherein the thickness is set to be 30 μm or more. The metal foil is a copper foil,
The inner metal foil has a thickness of 15 μm or less,
The thickness of the outermost metal foil disposed adjacent to the mixture of the preform foils in the final laminate is 20 μm or more,
When the outermost metal foil is disposed adjacent to the metal foil of the preform foil in the final laminate, the thickness of the outermost metal foil is the total thickness of the adjacent metal foils The manufacturing method of the composite material of the metal and carbon fiber of Claim 4 currently set so that may become 20 micrometers or more.   The manufacturing method of the composite material of the metal and carbon fiber in any one of Claims 4-6 further equipped with the drying process which dries the said mixture layer of the said preform foil before the said laminated body formation process. .

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