Bonded body of carbon material and copper material and method for producing the same

Abstract

To provide a bonded body of a carbon material and a copper material having high durability in a high-temperature environment without using expensive materials, and a method for manufacturing the same. 【Solution means】In a bonded body of a carbon material (1) made of artificial graphite or a carbon fiber reinforced carbon composite material and a copper material (2) made of pure copper or a chromium-containing copper alloy, an intermediate layer (3a) in which titanium, phosphorus, and carbon are dissolved in the copper matrix is provided between the carbon material and the copper material.

Description

Technical Field

[0001] The present invention relates to a bonded body of a carbon material and a copper material in which a copper material made of pure copper or a copper alloy is bonded to the carbon material, and a method for manufacturing the same.

Background Art

[0002] In a fusion reactor that confines high-temperature plasma, devices such as a first wall, a protection limiter, and a divertor are installed as plasma-facing devices installed in a portion where the plasma contacts. The divertor is a device for removing surplus gas and impurities, and the divertor plate used for this divertor is required to have excellent heat resistance, high thermal conductivity, and low emissivity characteristics. And for the divertor plate, carbon materials such as artificial graphite and carbon fiber reinforced carbon composite materials that satisfy these requirements can be used.

[0003] The carbon material that comes into contact with the plasma and becomes high temperature is equipped with a heat sink on the side opposite to the contact side with the plasma and is strongly cooled. The heat sink is preferably formed of a copper material such as pure copper (Cu), chromium copper (CuCr), chromium zirconium copper (CuCrZr), etc., which are materials excellent in heat conduction. At this time, it is required that the heat is well transmitted from the carbon material to the copper material, and the carbon material and the copper material are firmly joined with high adhesion so that the carbon material and the copper material do not separate.

[0004] However, since the reactivity between the carbon material and the copper material is low, it is not easy to directly bond them. Therefore, for bonding the carbon material and the copper material, a brazing material made of gold, silver, or an alloy thereof is often used.

[0005] For example, Patent Document 1 discloses that the surface of a C / C composite (carbon fiber reinforced carbon composite) or a graphite material as a carbon material is metallized with a coating of a brazing material containing Ti-Cu-Ag, a nickel (Ni) plate is interposed as a stress relaxation layer between this carbon material and a copper water-cooled plate, and they are joined using a gold (Au) brazing material or a silver (Ag) brazing material or the like. Further, Patent Document 2 discloses that a carbon material and a copper material (electrolytic copper) are joined by heating to 1050°C in a nitrogen atmosphere using a gold brazing material and an iron foil.

[0006] On the other hand, in Patent Document 3, the joining of a carbon material and a copper material (copper plate) is performed in two steps. In the first step, a carbon material, a copper foil, an iron plate, and a molybdenum plate are stacked and loaded, and heated to 1200°C in a nitrogen atmosphere to form a joined body in which these are joined. In the next step, a copper material is placed on the joined body via a gold brazing material, and heated to 950°C in a nitrogen atmosphere to form a joined body of the carbon material and the copper material. This Patent Document 3 also discloses that a carbon material, a gold brazing foil, an iron foil, a molybdenum foil, a gold brazing foil, and a copper material are placed in this order, loaded, and heated to 950°C in a nitrogen atmosphere to join the carbon material and the copper material.

[0007] Also, for example, in Patent Document 4, after applying a paste obtained by adding and mixing a synthetic resin and butanol to a mixed powder of copper powder and titanium powder to the surface of a carbon material, it is heated to 1300°C in a vacuum atmosphere to form a copper alloy-coated carbon material. Then, a copper material (copper block) is pressed against the copper alloy-coated surface of the carbon material at 2 MPa, and heated to 1050°C or 1060°C in a vacuum atmosphere to join the carbon material and the copper material.

[0008] Patent Document 5 discloses that a carbon material and a copper material are joined by heating, for example, to 800°C in a vacuum while sandwiching a pure nickel sheet between the carbon material and the copper material and applying pressure.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

[0010] However, in addition to the low durability of the brazing materials in Patent Documents 1 to 3 under high-temperature environments, they are expensive because they contain gold or silver, resulting in an increase in manufacturing costs. Therefore, there has been a situation where a bonded body of a carbon material and a copper material that can be used, for example, as a divertor plate, has not been obtained. Further, in Patent Documents 2 and 4, although the temperature is below the melting point of copper, since the copper material is joined by heating to a temperature close to this, there has been a problem that the copper material is likely to deform during joining. On the other hand, in Patent Document 5, it has been found that nickel and the carbon material do not sufficiently react, and it is difficult to obtain a bonded body of a carbon material and a copper material that are sufficiently adhered.

[0011] The present invention has been made in view of the above problems, and an object thereof is to provide a bonded body of a carbon material and a copper material that is inexpensive and has excellent durability under high-temperature environments, and a method for manufacturing the same. [Means for Solving the Problems]

[0012] The bonded body of a carbon material and a copper material according to the invention of claim 1 is a bonded body of a carbon material made of artificial graphite or a carbon fiber reinforced carbon composite material and a copper material made of pure copper or a chromium-containing copper alloy, characterized in that there is an intermediate layer in which titanium, phosphorus, and carbon are dissolved in the copper matrix between the carbon material and the copper material.

[0013] According to the above configuration, the carbon material and the copper material are joined through an intermediate layer in which titanium, phosphorus, and carbon are dissolved in the copper matrix. The intermediate layer containing titanium and phosphorus in the copper matrix reacts with the copper material and is firmly joined. Further, titanium contained in the intermediate layer reacts with the carbon material, and carbon is dissolved in the copper matrix, and the intermediate layer and the carbon material are firmly joined. This intermediate layer does not contain gold or silver, which are expensive joining materials, and has high durability in a high-temperature environment. Therefore, it is possible to obtain a joined body of a carbon material and a copper material that is inexpensive, has excellent durability in a high-temperature environment, and has sufficient joining strength.

[0014] The joined body of a carbon material and a copper material according to the invention of claim 2 is characterized in that, in the invention of claim 1, the intermediate layer has a region where the content ratio of titanium is large in the vicinity of the interface with the carbon material. According to the above configuration, the reaction between carbon and titanium is promoted in the vicinity of the interface between the carbon material and the intermediate layer, and a joined body of the carbon material and the copper material in which the carbon material and the intermediate layer are firmly joined can be obtained.

[0017] Claim 3 The joined body of a carbon material and a copper material according to the invention of is characterized in that, in the invention of claim, a refrigerant passage for allowing a refrigerant to flow is formed in the copper material. 1 or 2 According to the above configuration, it is possible to cool the copper material by flowing a refrigerant and transfer the heat of the carbon material to the copper material to cool the carbon material. Therefore, it is possible to obtain a joined body of a carbon material and a copper material having excellent durability in a high-temperature environment, and for example, it can be used as a plasma-facing device of a fusion reactor or a heat sink of a high-temperature heat treatment furnace.

[0018] 4 Claim 4The manufacturing method of the bonded body of the carbon material and the copper material of the invention is a method for manufacturing a bonded body of a carbon material made of artificial graphite or a carbon fiber reinforced carbon composite material and a copper material made of pure copper or a chromium-containing copper alloy, through an intermediate material. In this method, the intermediate material is a laminate of a titanium foil and a phosphorus copper foil. While clamping the carbon material and the copper material that sandwich the intermediate material in the stacking direction in the stacking direction and applying pressure, by heating in a non-oxidizing atmosphere by an electric current heating method to a temperature equal to or higher than the melting point of the phosphorus copper foil and lower than the melting point of the copper material, the carbon material and the copper material are bonded. This is the characteristic of the method.

[0019] According to the above configuration, an intermediate material formed by laminating a titanium foil and a phosphorus copper foil is sandwiched between a carbon material and a copper material in the stacking direction of the intermediate material, and in a state where pressure is applied in the stacking direction, by the electric current heating method equal to or higher than the melting point of the phosphorus copper foil It is heated to a temperature lower than the melting point of the copper material to bond the carbon material and the copper material. At this time, in the intermediate material, an alloy phase (intermediate layer) in which titanium is dissolved in the copper matrix phase can be formed at a low temperature by the phosphorus copper foil having a melting point lower than that of the copper material. Therefore, at a temperature lower than the melting point of the copper material, this alloy phase and the copper material can be reacted to be firmly bonded, and the reaction between titanium contained in the alloy phase and the carbon material can be promoted to dissolve carbon in the alloy phase, and the alloy phase and the carbon material can be bonded. And in the intermediate material, expensive materials such as gold and silver are not used, and a bonded body of a carbon material and a copper material that is inexpensive, has excellent durability in a high-temperature environment, and has sufficient bonding strength can be obtained.

[0020] Claim 5 The manufacturing method of the bonded body of the carbon material and the copper material of the invention is, in the invention of claim 4 In the invention, the intermediate material is characterized in that the phosphorus copper foil is laminated so as to sandwich the titanium foil from both sides. According to the above configuration, since the phosphorus copper foils exist on both sides of the titanium foil, the formation of an alloy phase of titanium and copper can be promoted.

[0021] Claim 6The manufacturing method of the bonded body of the carbon material and the copper material of the invention is a method for manufacturing a bonded body of a carbon material made of artificial graphite and a copper material made of pure copper or a chromium-containing copper alloy, through an intermediate material. In this method, the intermediate material is a laminate of a copper or copper alloy foil with a thickness of 0.01 mm to 0.1 mm and a stainless steel foil with a thickness of 0.15 mm to 0.2 mm. With the carbon material sandwiching the copper or copper alloy foil and the stainless steel foil being pressurized in the lamination direction of the intermediate material, by means of electric current heating in a non-oxidizing atmosphere at a temperature higher than the melting point of copper and lower than the melting point of the stainless steel foil for 10 minutes, a first bonding step of forming an intermediate bonded body by bonding the carbon material and the intermediate material is carried out. And a second bonding step of bonding the intermediate bonded body and the copper material, in which the copper material is brought into close contact with the intermediate material side of the intermediate bonded body while being pressurized in the lamination direction, and by means of electric current heating in a non-oxidizing atmosphere at 900 °C which is lower than the melting point of the copper material for 10 minutes.

[0022] According to the above configuration, with a thickness of 0.01 mm to 0.1 mm a foil made of copper or a copper alloy and with a thickness of 0.15 mm to 0.2 mm an intermediate material formed by laminating a stainless steel foil and made of artificial graphite the carbon material are bonded in the first bonding step to form an intermediate bonded body, and this intermediate bonded body and the copper material are bonded in the second bonding step to form a bonded body of the carbon material and the copper material. In the first bonding step, the carbon material and the stainless steel foil sandwich the copper or copper alloy foil, and while being pressurized in the lamination direction of the intermediate material, by means of electric current heating higher than the melting point of copper and higher than the melting point of the stainless steel foil at a low temperature for 10 minutes is heated. As a result, the copper or copper alloy foil, the stainless steel foil, and the carbon material, which are the intermediate materials, react, and an intermediate bonded body in which an intermediate material having an alloy phase in which iron and carbon are solid-solved in the copper matrix phase is bonded to the carbon material is formed. In the second bonding step, while pressurizing the copper material to be in close contact with the intermediate material of the intermediate bonded body, by means of electric current heating at a temperature lower than the melting point of the copper material at 900 °C for 10 minutesHeat it. As a result, the intermediate material containing copper and the copper material react and are joined, and a joined body of the carbon material and the copper material in which the carbon material and the copper material are joined via the intermediate material is formed. The intermediate material does not use gold and silver, which are expensive materials, and can be a joined body of a carbon material and a copper material that is inexpensive, has excellent durability in a high-temperature environment, and has sufficient joining strength. In addition, the residual stress after bonding can be relaxed, and good thermal conductivity in the intermediate material can be maintained.

[0023] Claim 7 The method for manufacturing a joined body of a carbon material and a copper material according to the invention of claim is a method for manufacturing a joined body of a carbon material and a copper material, wherein the carbon material made of a carbon fiber reinforced carbon composite material and the copper material made of pure copper or a chromium-containing copper alloy are joined via an intermediate material. The intermediate material is a laminate of a copper foil with a thickness of 0.02 mm and a stainless steel foil with a thickness of 0.05 mm. With the carbon material sandwiching the copper foil and the stainless steel foil pressed in the lamination direction of the intermediate material, heating is performed at a temperature higher than the melting point of copper and lower than the melting point of the stainless steel foil for 10 minutes in a non-oxidizing atmosphere by an electric heating method to form an intermediate joined body in which the carbon material and the intermediate material are joined. A first joining step; a second joining step of joining the intermediate joined body and the copper material by heating at 900 ° C. lower than the melting point of the copper material for 10 minutes in a non-oxidizing atmosphere by an electric heating method while pressing in the lamination direction so that the copper material is in close contact with the intermediate material side of the intermediate joined body. According to the above configuration, an intermediate material obtained by laminating a copper foil with a thickness of 0.02 mm and a stainless steel foil with a thickness of 0.05 mm, and a carbon material made of a carbon fiber reinforced carbon composite material are joined in a first joining step to form an intermediate joined body, and this intermediate joined body and a copper material are joined in a second joining step to form a joined body of the carbon material and the copper material. In the first joining step, the carbon material and the stainless steel foil sandwich the copper foil, and while being pressed in the lamination direction of the intermediate material, they are heated for 10 minutes at a temperature higher than the melting point of copper and lower than the melting point of the stainless steel foil by means of electric current heating. As a result, the copper foil, the stainless steel foil, and the carbon material, which are the intermediate materials, react, and an intermediate joined body in which an intermediate material having an alloy phase in which iron and carbon are solid-solved in the copper matrix phase is joined to the carbon material is formed. In the second joining step, while pressing the copper material so as to be in close contact with the intermediate material of the intermediate joined body, it is heated for 10 minutes at 900 °C, which is lower than the melting point of the copper material, by means of electric current heating. As a result, the intermediate material containing copper and the copper material react and are joined, and a joined body of the carbon material and the copper material in which the carbon material and the copper material are joined via the intermediate material is formed. The intermediate material does not use expensive materials such as gold and silver, and a joined body of the carbon material and the copper material that is inexpensive, has excellent durability in a high-temperature environment, and has sufficient joining strength can be obtained. In addition, the residual stress after joining can be relaxed, and good thermal conductivity in the intermediate material can be maintained.

Advantages of the Invention

[0024] According to the joined body of the carbon material and the copper material of the present invention and the manufacturing method thereof, the durability in a high-temperature environment can be increased without using expensive materials.

Brief Description of the Drawings

[0025]

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Figure 9

Mode for Carrying Out the Invention

[0026] Hereinafter, the mode for carrying out the present invention will be described in detail, but the present invention is not limited to the following embodiments.

[0027] As shown in FIGS. 1 and 2, a fusion reactor that confines high-temperature plasma is equipped with a divertor for removing surplus gas and impurities, and a plurality of divertor plates A used in this divertor are arranged and attached. The divertor plate A serves as a shielding member against the high-temperature plasma flow.

[0028] As shown in FIG. 3, for example, the divertor plate A is formed of a bonded body of a carbon material 1 having excellent heat resistance and thermal conductivity used because high-temperature plasma contacts it, and a copper material 2 for fixing and cooling the carbon material 1. And a refrigerant passage for flowing, for example, cooling water as a refrigerant is provided so as to pass through the inside of the copper material 2. By the flow of the refrigerant flowing in from the inlet B of this refrigerant passage and flowing out from the outlet C, the copper material 2 is cooled, and heat moves from the carbon material 1 to the copper material 2, and the carbon material 1 is cooled. This bonded body of the carbon material 1 and the copper material 2 can also be applied to a first wall or a protection limiter which are plasma-facing devices of a fusion reactor, and can also be applied as a heat sink of a heat treatment furnace. Incidentally, the shape and size can be set according to the application.

[0029] As the carbon material 1, commercially available products such as artificial graphite and C / C composites (carbon fiber carbon composites) can be used. As the copper material 2, commercially available products of pure copper or chromium-containing copper alloys such as chromium copper (CuCr) and chromium zirconium copper (CuCrZr), which are easier to handle because they have a higher hardness than pure copper, can be used.

[0030] The thickness of the carbon material 1 used for the divertor plate A of the fusion reactor is, for example, about 5 mm to 30 mm, but it is not limited to this and can be appropriately determined according to the application and the like. Also, the thickness of the copper material 2 used for the divertor plate A is, for example, about 10 mm to 30 mm, but it is not limited to this and can be appropriately determined according to the application and the like. The sizes other than the thicknesses of the carbon material 1 and the copper material 2 can also be appropriately set according to the application and the like.

[0031] Since the carbon material 1 and the copper material 2 have low reactivity and are difficult to directly bond, an intermediate material 3 is interposed between the carbon material 1 and the copper material 2 for bonding. Specifically, with the intermediate material 3 sandwiched, the carbon material 1 and the copper material 2 are heated and bonded by the electric current heating method at a temperature below the melting point of copper in a non-oxidizing atmosphere (in a vacuum or an inert gas atmosphere such as argon gas) while being pressurized (compressed). The electric current heating method is a method of directly heating a conductive heating object by passing an electric current through the heating object and using the Joule heat generated according to the electric resistance of the heating object. At the same time, a high-temperature plasma state is generated in the gap between the carbon material 1 and the copper material 2 close to the intermediate material 3, and it is considered that the surrounding is melted and a necking structure is constructed and bonded.

[0032] As the electric current heating method, the spark plasma sintering method (SPS method) is preferable. The spark plasma sintering method uses a pulsed electric current pressurized sintering device to heat the heating object by applying a direct current pulse of a large electric current to the heating object while pressurizing it. Since Joule heat and a thermal plasma state are generated according to the electric resistance of the heating object, the heating temperature can be controlled by the current value, the energization time, the energization cycle, etc.

[0033] A cylindrical test piece for evaluating a joined body of a carbon material 1 and a copper material 2 will be described. The carbon material 1 of the test piece is obtained by processing artificial graphite or a C / C composite into a cylindrical shape. As the C / C composite, a laminate in which a plurality of felt C / C composites are laminated in the direction of arrow D as shown in FIG. 4, or a 1D-C / C composite in which the fiber axis directions of carbon fibers are aligned in the direction of arrow E as shown in FIG. 5 is processed into a cylindrical shape with a diameter of 9.5 mm and an axial length (thickness) of 10 mm. The axial direction of this cylinder is set to be orthogonal to the felt lamination direction indicated by arrow D with respect to the laminate of the felt C / C composite and parallel to the fiber axis direction of the carbon fibers indicated by arrow E with respect to the 1D-C / C composite as the direction in which heat is easily transmitted.

[0034] The copper material 2 is obtained by processing a chromium-containing copper alloy into a cylindrical shape with a diameter of 9.5 mm and an axial length (thickness) of 10 mm. The intermediate material 3 is a laminate (stacked) of a titanium foil and a phosphor copper foil each processed into a circular shape with a diameter of 9.5 mm, or a laminate (stacked) of a stainless steel foil (SUS316L foil) and a copper foil each processed into a circular shape with a diameter of 9.5 mm.

[0035] As shown in FIG. 6, using the pulsed electric current pressure sintering apparatus 10, while applying pressure to a placement in which the intermediate material 3 is sandwiched between the carbon material 1 and the copper material 2 as a heating target, a direct current pulsed electric current is applied to this heating target to heat it, thereby forming a joined body of the carbon material 1 and the copper material 2 as shown in FIG. 7 as a cylindrical test piece.

[0036] The pulsed electric current pressure sintering apparatus 10 in FIG. 6 will be described. The pulse current pressure sintering apparatus 10 has, inside a casing 11, a cylindrical die 12 made of artificial graphite with an inner diameter of 10 mm, and a pair of punches 13, 14 made of artificial graphite in a cylindrical shape with a diameter of 9.5 mm inserted into the die 12 from the vertical direction. Between the pair of punches 13, 14, a heating object stacked in the order of, for example, a carbon material 1, an intermediate material 3, and a copper material 2 from the bottom is placed. The heating object is mechanically pressed (compressed) via the pair of punches 13, 14. In addition, in order to prevent the heating object from sticking to the punches 13, 14, graphite sheets (not shown) having the same diameter as the punches 13, 14 and a thickness of 0.2 mm are respectively sandwiched between the heating object and the punches 13, 14.

[0037] As a lower jig, a spacer 15 made of artificial graphite that becomes smaller toward the punch 13 side is provided. Similarly, as an upper jig, a spacer 16 made of artificial graphite that becomes smaller toward the punch 14 side is provided.

[0038] The die 12 has an opening in the middle side surface portion, and the temperature (heating temperature) of the heating object is measured by a thermocouple 17 inserted into this opening. A carbon felt (not shown) with a thickness of 5 mm is attached to cover the outer periphery of the die 12 for heat insulation. The casing 11 hermetically covers the surroundings of these upper and lower jigs, the die 12, and the pair of punches 13, 14.

[0039] The pulse current pressure sintering apparatus 10 has a pressure unit 18, a pulse power source 19, a cooling mechanism 20, and a vacuum unit 21. The vacuum unit 21 evacuates the inside of the casing 11 to maintain a vacuum state. The pressure unit 18 presses the heating object via the upper and lower jigs and the punches 13, 14. The pulse power source 19 applies a DC pulse current to the heating object via the punches 13, 14. The cooling mechanism 20 constantly circulates a refrigerant to cool at least the pair of punches 13, 14. Since this pulse current pressure sintering apparatus 10 is used to heat by the electric current heating method, the heat generation of the carbon material 1 having a larger electric resistance than the copper material 2 and the intermediate material 3 becomes larger. In addition, since the punches 13, 14 are cooled, the copper material 2 does not rise in temperature to the heating temperature except for the portion on the intermediate material 3 side, so the copper material 2 is difficult to deform during joining.

[0040] Next, the evaluation of the test piece will be described. As shown in Fig. 7, in the cylindrical test piece, the central portion in the axial direction is the joint portion between the carbon material 1 and the copper material 2. For this test piece, using an electronic universal testing machine (CATY-2002S manufactured by Yonekura Seisakusho Co., Ltd.), stress was applied at a crosshead speed of 1 mm / min in shear mode to measure the shear strength of the joint portion. In the test piece, it can be said that the higher the shear strength, the stronger the joint. In addition, the joint portion of the test piece was analyzed using a scanning electron microscope (SEM: Scanning Electron Microscope) and an energy dispersive X-ray analyzer (JSM-IT200 manufactured by JEOL Ltd.).

[0041] Test pieces of Examples 1 to 15 and Comparative Examples 1 to 4 with different formation conditions of the test pieces (combinations of carbon material 1, intermediate material 3, and copper material 2, heating temperature, heating time, and pressure) were produced and evaluated. In Examples 1 to 11, phosphor copper foil and titanium foil were used as the intermediate material 3, and in Examples 12 to 15, copper foil and stainless steel foil were used as the intermediate material 3. For the formation of the test pieces, a pulse current pressure sintering apparatus (model: SPS-515S, maximum load 50 kN, maximum pulse current output 1500 A) manufactured by Sumitomo Coal Mining Co., Ltd. was used.

[0042] The heating conditions of the test pieces common to Examples 1 to 15 and Comparative Examples 1 to 4 are shown. The atmosphere was a vacuum with a degree of vacuum of about 20 Pa. The heating rate was 50°C / min to 100°C / min from room temperature to the heating temperature (maximum temperature). After the heating time (the time to maintain the heating temperature) elapsed, heating was stopped and natural cooling was performed in a vacuum state. The cooling rate at this time was 30°C / min to 80°C / min. After reaching 200°C or lower, the pressure was returned to atmospheric pressure and the test piece was taken out.

[0043] Table 1 shows the individual formation conditions of Examples 1 to 6 and Comparative Example 1 and the results of the joint evaluation of the obtained test pieces. As the carbon material 1, artificial graphite (IG-430U manufactured by Toyo Tanso Co., Ltd., bulk density 1.82 g / cm 3, isotropic graphite) was used. As the intermediate material 3, phosphor copper foil (BC-106 manufactured by Toyo Yozai Co., Ltd., an alloy foil of 94% by mass of copper and 6% by mass of phosphorus, melting temperature: solidus 705 °C, liquidus 850 °C) and titanium foil (TR270C manufactured by Takeuchi Metal Foil & Powder Industry Co., Ltd., 99.5% by mass of titanium) were used. Since the melting point of phosphor copper is about 700 °C to 850 °C, it is considered that a solid solution with titanium is formed at a temperature above this melting point, and joining is possible at about 700 °C to 850 °C.

[0044] The thickness of the titanium foil suitable as the intermediate material 3 is 0.01 mm to 0.5 mm, more preferably 0.05 mm to 0.3 mm, and still more preferably 0.05 mm to 0.15 mm. If the thickness is less than 0.01 mm, there is too little titanium and it becomes difficult to obtain good joining. When the thickness is greater than 0.5 mm, the intermediate layer 3a formed by the reaction of the intermediate material 3 may become too thick and the thermal conductivity may decrease. Similarly, the thickness of the phosphor copper foil suitable as the intermediate material 3 is 0.01 mm to 0.5 mm, more preferably 0.05 mm to 0.3 mm, and still more preferably 0.05 mm to 0.15 mm. In this case, a titanium foil with a thickness of 0.15 mm and a phosphor copper foil with a thickness of 0.1 mm were used.

[0045]

Table 1

[0046] In Examples 1 to 6 and Comparative Example 1, the carbon material 1 was common as artificial graphite and the copper material 2 was chromium zirconium copper, and test pieces were formed by changing the composition, heating temperature, and heating time of the intermediate material 3. The pressure was 40 MPa in all cases. It has been confirmed that a joined body of the carbon material 1 and the copper material 2 can be formed in the same manner even when the copper material 2 is chromium copper or pure copper.

[0047] In Examples 1 to 3, a phosphor copper foil with a thickness of 0.1 mm was laminated so as to sandwich a titanium foil with a thickness of 0.15 mm from both sides, and heated at 920 °C, 900 °C, and 850 °C for 10 minutes, respectively. In Example 4, as the intermediate material 3, it was laminated so that the carbon material 1 side was a phosphor copper foil with a thickness of 0.1 mm and the copper material 2 side was a titanium foil with a thickness of 0.15 mm, and heated at 920 °C for 10 minutes. In Example 5, as the intermediate material 3, it was laminated so that the carbon material 1 side was a titanium foil with a thickness of 0.15 mm and the copper material 2 side was a phosphor copper foil with a thickness of 0.1 mm, and heated at 920 °C for 10 minutes. In Example 6, the intermediate material 3 having the same configuration as in Example 5 was used and heated at 920 °C for 30 minutes. In Comparative Example 1, the intermediate material 3 having the same configuration as in Example 5 was used and heated at 830 °C for 10 minutes.

[0048] Compared with Comparative Example 1, all of Examples 1 to 6 have higher shear strength, and the carbon material 1 and the copper material 2 are firmly joined. According to Examples 1 to 3, the higher the heating temperature, the higher the shear strength. In Examples 1 and 2, the carbon material 1 (artificial graphite) is broken without breaking at the joint.

[0049] According to Examples 1, 4, and 5 with the same heating conditions, Example 1 with a larger amount of phosphor copper foil as the intermediate material 3 has higher shear strength than Examples 4 and 5, and Examples 4 and 5 are broken at the interface between the carbon material 1 and the intermediate material 3. Also, the shear strength of Example 4 in which the phosphor copper foil is disposed on the carbon material 1 side is higher than that of Example 5 in which the titanium foil is disposed on the carbon material 1 side. And according to Examples 5 and 6 in which the titanium foil is disposed on the carbon material 1 side, the shear strength of Example 6 with a longer heating time is higher than that of Example 5.

[0050] From the above results, it is possible to form a joined body of the carbon material 1 made of artificial graphite and the copper material 2 by using the intermediate material 3 composed of a phosphor copper foil and a titanium foil. In particular, by using the intermediate material 3 having a structure in which a titanium foil with a thickness of 0.15 mm is sandwiched between phosphor copper foils with a thickness of 0.1 mm and heating at a heating temperature of 850°C to 920°C for 10 minutes, a joined body of the carbon material 1 and the copper material 2 with high shear strength can be efficiently formed. At this time, it is considered that the reaction between the molten phosphor copper foil and the titanium foil is promoted by phosphorus, and the reaction between titanium dissolved in the copper matrix and the carbon material is promoted.

[0051] Table 2 shows the individual formation conditions of Examples 7 to 11 and Comparative Example 2 and the results of the joint evaluation of the obtained test pieces. Here, as the carbon material 1, a felt C / C composite (TCC-123U manufactured by Toyo Tanso Co., Ltd., bulk density 1.49 g / cm 3 ), or a 1D-C / C composite (MFC-1 manufactured by Mitsubishi Chemical Corporation, bulk density 1.96 g / cm 3 ) was used. The copper material 2, the phosphor copper foil and the titanium foil of the intermediate material 3 are the same as those in Example 1 and the like.

[0052]

Table 2

[0053] Examples 7 to 11 and Comparative Example 2 are common in that the carbon material 1 is a C / C composite, the copper material 2 is a chromium zirconium copper, and the intermediate material 3 has a structure in which a titanium foil with a thickness of 0.15 mm is sandwiched between phosphor copper foils with a thickness of 0.1 mm, and test pieces were formed by changing the heating temperature. The C / C composites of Examples 7 to 10 and Comparative Example 2 are felt C / C composites, and only Example 11 is a 1D-C / C composite.

[0054] Examples 7 to 10 and Comparative Example 2 were heated at heating temperatures of 920°C, 900°C, 850°C, 800°C, and 720°C for 10 minutes, respectively. Example 11 was heated at the same heating temperature (920°C) as Example 7. The pressure was 5 MPa in all cases, and the heating time was 10 minutes in all cases.

[0055] Compared with Comparative Example 2 having the lowest heating temperature, Examples 7 to 11 all have high shear strength, and the carbon material 1 and the copper material 2 are firmly joined. According to Examples 7 to 10, the higher the heating temperature, the higher the shear strength, and at the joint, the carbon material 1 (felt C / C composite) is broken instead of being broken at the joint. In Example 11, since it is difficult to break in the direction of cutting the carbon fibers of the carbon material 1 (1D-C / C composite), the shear strength is higher than that of Examples 7 to 10, but it is broken at the interface between the carbon material 1 and the intermediate material 3.

[0056] From the above results, by using the intermediate material 3 having a structure in which the carbon material 1 made of C / C composite and the titanium foil with a thickness of 0.15 mm are laminated with a phosphor copper foil having a thickness of 0.1 mm and heating at 800 °C to 920 °C for 10 minutes, a joined body of the carbon material 1 and the copper material 2 having high shear strength can be efficiently formed.

[0057] For Example 2 and Example 7, SEM images of the joined portion of the carbon material 1 and the copper material 2 are shown in FIGS. 8 and 9. An intermediate layer 3a that looks slightly darker than the copper material 2 is seen between the carbon material 1 that looks dark and the copper material 2 that looks bright, and the intermediate layer 3a formed by the reaction of the intermediate material 3 is seen respectively. As a result of elemental analysis, all of the intermediate layers 3a contained carbon, phosphorus, titanium, chromium, and copper. Since carbon and chromium are derived from the carbon material 1 and the copper material 2 respectively, the intermediate material 3 made of phosphor copper foil and titanium foil reacts with the carbon material 1 and the copper material 2 to form the intermediate layer 3a, and the carbon material 1 and the copper material 2 are joined through this intermediate layer 3a.

[0058] In addition, in the vicinity of the interface between the carbon material 1 and the intermediate layer 3a, a region where the titanium content ratio is high in the intermediate layer 3a (the bright part between the carbon material 1 and the intermediate layer 3a) was formed. Although it varied depending on the analysis location, most of the intermediate layer 3a had about 60 atom / mol% to 80 atom / mol% of copper and about 10 atom / mol% to 30 atom / mol% of titanium. On the other hand, in the region where the titanium content ratio was high, the copper was about 10 atom / mol% to 40 atom / mol% and the titanium was about 40 atom / mol% to 60 atom / mol%. And the region where the titanium content ratio was high tended to have a high phosphorus content ratio. In the vicinity of the interface between the carbon material 1 and this intermediate layer 3a, it is considered that the reaction between the carbon material 1 (carbon) and titanium is promoted to form a strong bond. Moreover, an alloy phase containing at least titanium, copper, and phosphorus is observed inside the carbon material 1, and it is considered that a part of the intermediate layer 3a enters the voids of the carbon material 1 to reinforce the bond between the carbon material 1 and the intermediate layer 3a.

[0059] Table 3 shows the individual formation conditions of Examples 12 to 15 and Comparative Examples 3 and 4 and the results of the joint evaluation of the obtained test pieces. The above artificial graphite or felt C / C composite was used for the carbon material 1, and chromium copper or chromium zirconium copper was used for the copper material 2. As the intermediate material 3, a laminate of a commercially available copper foil and a stainless steel foil (SUS316L foil) was used. These copper foil and stainless steel foil react with the carbon material 1 to dissolve iron and carbon in the copper matrix phase, forming an intermediate layer 3a containing an alloy phase composed of Fe-Cu-C. This intermediate layer 3a is firmly joined to the carbon material 1.

[0060] The suitable thickness of the stainless steel foil as the intermediate material 3 is 0.1 mm to 1.0 mm, and more preferably 0.15 mm to 0.5 mm. If the thickness is less than 0.1 mm, the residual stress of the carbon material 1 becomes large and it is difficult to obtain sufficient joint strength. If the thickness exceeds 1.0 mm, the thermal conductivity tends to decrease, which is not preferable. Incidentally, an iron foil can be used instead of the stainless steel foil, but the stainless steel foil with a lower melting point is preferable because it can be joined at a lower temperature.

[0061] The suitable thickness of the copper foil or copper alloy foil as the intermediate material 3 is 0.01 mm to 0.5 mm, more preferably 0.01 mm to 0.3 mm, and even more preferably 0.01 mm to 0.1 mm. If it is less than 0.01 mm, the amount of copper is too small to obtain sufficient bonding strength. If it exceeds 0.5 mm, the amount of copper becomes excessive and the bonding is likely to be inhibited. Instead of the copper foil, a copper alloy foil may be used. The type of the copper alloy foil is not particularly limited, and a phosphor copper foil can be used.

[0062]

Table 3

[0063] In Examples 12 to 15 and Comparative Examples 3 and 4, a laminate of a stainless steel foil and a copper foil was used as the intermediate material 3, and test specimens were formed by changing the configuration of this intermediate material 3, the types of the carbon material 1 and the copper material 2, and the heating conditions. Through prior studies, it was found that in order to promote the reaction between the intermediate material 3 containing the stainless steel foil and the carbon material 1, a temperature around the melting point of copper (1085 °C) is required. Therefore, in order to avoid deformation of the copper material 2, a bonded body of the carbon material 1 and the copper material 2 was formed by two steps: a first bonding step of first bonding the carbon material 1 and the intermediate material 3 at a high temperature to form an intermediate bonded body, and a second bonding step of bonding the copper material 2 to the intermediate material 3 side of this intermediate bonded body at a lower temperature than the first bonding step. The heating time in the first bonding step was 10 minutes, the heating temperature in the second bonding step was 900 °C, and the heating time was 10 minutes.

[0064] In Example 12, artificial graphite was used as the carbon material 1, a 0.15-mm-thick stainless steel foil was stacked on a 0.01-mm-thick copper foil arranged on the carbon material 1 side as the intermediate material 3, and an intermediate bonded body was formed at a pressure of 10 MPa and a heating temperature of 1100 °C in the first bonding step. Then, in the second bonding step, the chromium copper of the copper material 2 and the intermediate bonded body were bonded at a pressure of 20 MPa.

[0065] Example 13 used artificial graphite as carbon material 1, and stacked a 0.2 mm thick stainless steel foil on a 0.1 mm thick phosphorus copper foil arranged on the carbon material 1 side as intermediate material 3. An intermediate joint was formed in the first joining step at a pressure of 40 MPa and a heating temperature of 1100 °C. Then, in the second joining step, the chromium zirconium copper of copper material 2 and the intermediate joint were joined at a pressure of 40 MPa.

[0066] Example 14 used artificial graphite as carbon material 1, and stacked a 0.2 mm thick stainless steel foil on a 0.02 mm thick copper foil arranged on the carbon material 1 side as intermediate material 3. An intermediate joint was formed in the first joining step at a pressure of 40 MPa and a heating temperature of 1200 °C. Then, in the same manner as in Example 13, the chromium zirconium copper of copper material 2 and the intermediate joint were joined in the second joining step.

[0067] Example 15 used a felt C / C composite as carbon material 1, and stacked a 0.05 mm thick stainless steel foil on a 0.02 mm thick copper foil arranged on the carbon material 1 side as intermediate material 3. An intermediate joint was formed in the first joining step at a pressure of 5 MPa and a heating temperature of 1100 °C. Then, in the second joining step, the chromium copper of copper material 2 and the intermediate joint were joined at a pressure of 5 MPa.

[0068] Comparative Example 3 used artificial graphite as carbon material 1, and stacked a 0.05 mm thick stainless steel foil on a 0.01 mm thick copper foil arranged on the carbon material 1 side as intermediate material 3, and formed an intermediate joint under the same heating conditions as in Example 12. Since cracks occurred in carbon material 1 in this intermediate joint, a joint of carbon material 1 and copper material 2 was not formed. Since the stainless steel foil was thinner (less amount of stainless steel foil) than in Example 12, the residual stress when forming the intermediate joint could not be completely relaxed, and it is considered that cracks occurred in carbon material 1. Although the thickness of the stainless steel foil in Example 15 is also 0.05 mm, since a felt C / C composite with lower rigidity than artificial graphite and thus stress-relieved is used as carbon material 1, it is considered that carbon material 1 did not break.

[0069] Comparative Example 4 was heated under the same conditions as Example 13, except that the heating temperature in the first bonding step was 1050°C, using the same carbon material 1 and intermediate material 3 as in Example 13. However, since the carbon material 1 and the intermediate material 3 were not joined and an intermediate joined body could not be formed, a joined body of the carbon material 1 and the copper material 2 could not be obtained.

[0070] Examples 12 to 14 obtained a bonding strength comparable to that of Examples 1 to 6 using artificial graphite as the carbon material 1. Also, in Examples 12 to 14, since the carbon material 1 was broken, the carbon material 1 and the copper material 2 were firmly joined. Example 15 had a lower bonding strength than Examples 7 to 10 using felt C / C composite as the carbon material 1, but since the carbon material 1 was broken, the carbon material 1 and the copper material 2 were firmly joined.

[0071] From the above results, using an intermediate material 3 having a structure in which a copper foil and a stainless steel foil (SUS316L) are laminated, an intermediate joined body is formed by heating at a heating temperature of 1100°C to 1200°C for 10 minutes in the first bonding step, and in the second bonding step, the intermediate joined body and the copper material 2 are joined by heating at a heating temperature of 900°C for 10 minutes, whereby a joined body of the carbon material 1 and the copper material 2 having high shear strength can be formed.

[0072] The thicknesses of the titanium foil, phosphor copper foil, stainless steel foil, copper foil, etc. are not limited to the above. Considering that the thermal conductivity between the carbon material 1 and the copper material 2 decreases as the intermediate layer 3a becomes thicker, it can be set so as to obtain sufficient bonding strength. The pressing pressure during bonding was 5 MPa to 40 MPa, but a pressing pressure at which the carbon material 1 and the copper material 2 are not damaged may be set. For example, depending on the thickness of the foil, heating conditions, etc., a part of the titanium foil or stainless steel foil may remain in layers, but even in this case, it is firmly joined to the carbon material 1 by titanium or iron dissolved in the copper matrix of the intermediate layer 3a.

[0073] When producing a bonded body of the carbon material 1 and the copper material 2 to be used for the diverter plate A or the like, the carbon material 1 and the copper material 2 may be bonded using a material, a jig, and a pulse current pressure sintering apparatus according to their sizes. The time for maintaining the heating temperature (heating time) is set according to the size of the object to be heated, but is preferably 5 to 60 minutes from the viewpoints of bonding strength and productivity. In addition, those skilled in the art can implement the invention in various modified forms without departing from the gist of the present invention, and the present invention includes such modified forms.

Explanation of Reference Numerals

[0074] 1: Carbon material 2: Copper material 3: Intermediate material 3a: Intermediate layer 10: Pulse current pressure sintering apparatus 11: Casing 12: Die 13, 14: Punch 15, 16: Spacer 17: Thermocouple 18: Pressing unit 19: Pulse power supply 20: Cooling mechanism 21: Vacuum unit

Claims

1. In a joined body of a carbon material made of artificial graphite or a carbon fiber reinforced carbon composite material and a copper material made of pure copper or a chromium-containing copper alloy, the joined body of the carbon material and the copper material is characterized in that an intermediate layer in which titanium, phosphorus, and carbon are dissolved in the copper matrix is provided between the carbon material and the copper material.

2. The joined body of the carbon material and the copper material according to Claim 1, wherein the intermediate layer has a region with a high titanium content ratio near the interface with the carbon material.

3. The joined body of the carbon material and the copper material according to Claim 1 or 2, wherein a refrigerant passage for allowing a refrigerant to flow is formed in the copper material.

4. In a method for manufacturing a joined body of a carbon material made of artificial graphite or a carbon fiber reinforced carbon composite material and a copper material made of pure copper or a chromium-containing copper alloy, the carbon material and the copper material being joined via an intermediate material, the intermediate material is a laminate of a titanium foil and a phosphorus copper foil, the carbon material and the copper material sandwiching the intermediate material in the stacking direction are heated in a non-oxidizing atmosphere by an electric current heating method to a temperature equal to or higher than the melting point of the phosphorus copper foil and lower than the melting point of the copper material while being pressed in the stacking direction, thereby joining the carbon material and the copper material. This is a method for manufacturing a joined body of a carbon material and a copper material.

5. The method for manufacturing a joined body of a carbon material and a copper material according to Claim 4, wherein the intermediate material is laminated such that the phosphorus copper foil sandwiches the titanium foil from both sides.

6. In a method for manufacturing a joined body of a carbon material made of artificial graphite and a copper material made of pure copper or a chromium-containing copper alloy, the carbon material and the copper material being joined via an intermediate material, the intermediate material is a laminate of a copper or copper alloy foil with a thickness of 0.01 mm to 0.1 mm and a stainless steel foil with a thickness of 0.15 mm to 0.2 mm, In a first joining step of forming an intermediate joined body by joining the carbon material and the intermediate material, the carbon material and the stainless steel foil sandwiching the copper or copper alloy foil are heated in a non-oxidizing atmosphere by an electric current heating method at a temperature higher than the melting point of copper and lower than the melting point of the stainless steel foil for 10 minutes while being pressed in the stacking direction of the intermediate material. A method for manufacturing a bonded body of a carbon material and a copper material, comprising a second bonding step of bonding the intermediate bonding body and the copper material by heating in a non-oxidizing atmosphere at 900 °C, which is lower than the melting point of the copper material, for 10 minutes by an electric current heating method while pressing in the stacking direction so that the copper material is in close contact with the intermediate material side of the intermediate bonding body.

7. In a method for manufacturing a bonded body of a carbon material and a copper material, wherein the carbon material made of a carbon fiber reinforced carbon composite material and the copper material made of pure copper or a chromium-containing copper alloy are bonded via an intermediate material, the intermediate material is a laminate of a copper foil with a thickness of 0.02 mm and a stainless steel foil with a thickness of 0.05 mm, a first bonding step of forming an intermediate bonding body by bonding the carbon material and the intermediate material by heating in a non-oxidizing atmosphere at a temperature higher than the melting point of copper and lower than the melting point of the stainless steel foil for 10 minutes by an electric current heating method while pressing the carbon material and the stainless steel foil sandwiching the copper foil in the stacking direction of the intermediate material; A method for manufacturing a bonded body of a carbon material and a copper material, comprising a second bonding step of bonding the intermediate bonding body and the copper material by heating in a non-oxidizing atmosphere at 900 °C, which is lower than the melting point of the copper material, for 10 minutes by an electric current heating method while pressing in the stacking direction so that the copper material is in close contact with the intermediate material side of the intermediate bonding body.

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