Joint of carbon material and copper material and method for manufacturing the same

Abstract

To provide a carbon and copper composite body with high durability in high-temperature environments without using expensive materials, and a method for manufacturing the same. [Solution] A carbon material (1) made of artificial graphite or carbon fiber reinforced carbon composite material and a copper material (2) made of pure copper or chromium-containing copper alloy are joined together to form a carbon material-copper material joint, which has an intermediate layer (3a) between the carbon material and the copper material in which titanium, phosphorus and carbon are solid-solved in the copper matrix.

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 bonded with high adhesion so that the carbon material and the copper material do not separate.

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

[0005] For example, Patent Document 1 discloses a method of joining a carbon material, such as a C / C composite (carbon fiber reinforced carbon composite material) or a graphite material, by metallizing the surface with a brazing material composed of Ti-Cu-Ag, interposing a nickel (Ni) plate as a stress relaxation layer between the carbon material and a copper water-cooled plate, and joining them using gold (Au) brazing material or silver (Ag) brazing material. Patent Document 2 also discloses a method of joining a carbon material and a copper material (electrolytic copper) by using gold brazing material and iron foil and heating them to 1050°C in a nitrogen atmosphere.

[0006] On the other hand, Patent Document 3 describes a two-step process for joining carbon material and copper material (copper plate). In the first step, carbon material, copper foil, iron plate, and molybdenum plate are stacked, a load is applied, and they are heated to 1200°C in a nitrogen atmosphere to form a joined body. In the next step, copper material is placed on the joined body via gold solder and heated to 950°C in a nitrogen atmosphere to form a joined body of carbon material and copper material. Patent Document 3 also discloses a method of joining carbon material and copper material by placing carbon material, gold solder foil, iron foil, molybdenum foil, gold solder foil, and copper material in that order, applying a load, and heating to 950°C in a nitrogen atmosphere.

[0007] Furthermore, as described in Patent Document 4, for example, a paste made by adding and mixing synthetic resin and butanol to a mixture of copper powder and titanium powder is applied to the surface of a carbon material, and then heated to 1300°C in a vacuum atmosphere to form a copper alloy coated carbon material. Then, the carbon material and copper material are joined by applying pressure of 2 MPa so that a copper material (copper block) is in close contact with the copper alloy coated surface of the carbon material, and then heating to 1050°C or 1060°C in a vacuum atmosphere.

[0008] Patent Document 5 discloses a method of joining carbon material and copper material by sandwiching a pure nickel sheet between them, applying pressure, and heating them to, for example, 800°C in a vacuum. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 63-310778 [Patent Document 2] Japanese Patent Application Publication No. 1-290567 [Patent Document 3] Japanese Patent Application Publication No. 3-218986 [Patent Document 4] Japanese Patent Application Publication No. 10-25173 [Patent Document 5] Japanese Patent Publication No. 2006-320951 [Overview of the project] [Problems that the invention aims to solve]

[0010] However, the brazing materials described in Patent Documents 1-3 had problems: in addition to having low durability in high-temperature environments, they were expensive because they contained gold or silver, which increased manufacturing costs. Therefore, no carbon-copper bonded material that could be used, for example, as a diverter plate had been obtained. Furthermore, in Patent Documents 2 and 4, the copper material was joined by heating it to a temperature close to, though below, the melting point of copper, which resulted in the copper material being prone to deformation during joining. On the other hand, in Patent Document 5, it was found that the nickel and carbon material did not react sufficiently, making it difficult to obtain a sufficiently bonded carbon-copper bonded material.

[0011] This invention has been made in view of the above-mentioned problems, and aims to provide an inexpensive bonded body of carbon material and copper material with excellent durability in high-temperature environments, as well as a method for manufacturing the same. [Means for solving the problem]

[0012] The carbon-copper joint of the invention of claim 1 is a carbon-copper joint formed by joining a carbon material made of artificial graphite or carbon fiber reinforced carbon composite material with a copper material made of pure copper or chromium-containing copper alloy, characterized in that there is an intermediate layer between the carbon material and the copper material in which titanium, phosphorus, and carbon are solid-solved in the copper matrix.

[0013] According to the above configuration, the carbon material and the copper material are joined via an intermediate layer in which titanium, phosphorus, and carbon are solid-dissolved in the copper matrix. The intermediate layer containing titanium and phosphorus in the copper matrix reacts with the copper material to form a strong bond. Furthermore, the titanium contained in the intermediate layer reacts with the carbon material, causing the carbon to solid-dissolve in the copper matrix, resulting in a strong bond between the intermediate layer and the carbon material. This intermediate layer does not contain expensive bonding materials such as gold or silver, and therefore has high durability in high-temperature environments. Thus, it is possible to create a carbon-copper joint that is inexpensive, has excellent durability in high-temperature environments, and possesses sufficient bonding strength.

[0014] The carbon material and copper material joint of the invention of claim 2 is characterized in that, in the invention of claim 1, the intermediate layer has a region with a high titanium content near the interface with the carbon material. According to the above configuration, the reaction between carbon and titanium is promoted near the interface between the carbon material and the intermediate layer, resulting in a carbon material-copper material bond in which the carbon material and the intermediate layer are firmly joined.

[0015] The carbon material-copper material joint of the invention of claim 3 is a carbon material-copper material joint formed by joining a carbon material made of artificial graphite or carbon fiber reinforced carbon composite material with a copper material made of pure copper or chromium-containing copper alloy, characterized in that there is an intermediate layer between the carbon material and the copper material in which iron and carbon are solid-solved in the copper matrix.

[0016] According to the above configuration, the carbon material and the copper material are joined via an intermediate layer in which iron and carbon are solid-dissolved in the copper matrix. The intermediate layer, in which iron is solid-dissolved in the copper matrix, reacts with the copper material to form a strong bond. Furthermore, the iron contained in the intermediate layer reacts with the carbon material, causing carbon to solid-dissolve in the copper matrix, resulting in a strong bond between the intermediate layer and the carbon material. This intermediate layer does not contain expensive materials such as gold or silver, and therefore has high durability in high-temperature environments. Thus, it is possible to create a carbon-copper joint that is inexpensive, has excellent durability in high-temperature environments, and possesses sufficient bonding strength.

[0017] The carbon material and copper material joint of the invention of claim 4 is characterized in that, in the invention of any one of claims 1 to 3, a refrigerant passage for circulating a refrigerant is formed in the copper material. According to the above configuration, the copper material can be cooled by circulating a coolant, and the heat from the carbon material can be transferred to the copper material to cool the carbon material. Therefore, a carbon-copper joint with excellent durability in high-temperature environments can be created, and it can be used, for example, as a plasma-facing device in a nuclear fusion reactor or as a heat sink in a high-temperature heat treatment furnace.

[0018] The method for manufacturing a carbon material-copper material joint according to claim 5 is a method for manufacturing a carbon material-copper material joint in which a carbon material made of artificial graphite or carbon fiber reinforced carbon composite material and a copper material made of pure copper or chromium-containing copper alloy are joined via an intermediate material, wherein the intermediate material is made of laminated titanium foil and phosphor copper foil, and the carbon material and the copper material sandwiching the intermediate material in the lamination direction are pressed in the lamination direction, and the carbon material and the copper material are joined by heating to a temperature below the melting point of the copper material in a non-oxidizing atmosphere using an electric heating method.

[0019] According to the above configuration, an intermediate material made of laminated titanium foil and phosphor copper foil is sandwiched between carbon material and copper material in the direction of the intermediate material's lamination, and while under pressure in that lamination direction, the carbon material and copper material are joined by heating to a temperature lower than the melting point of the copper material using an electric heating method. At this time, in the intermediate material, the phosphor copper foil, which has a lower melting point than the copper material, can form an alloy phase (intermediate layer) in which titanium is solid-dissolved in the copper matrix at a low temperature. Therefore, at a temperature lower than the melting point of the copper material, this alloy phase and the copper material can be reacted and strongly joined, and the reaction between the titanium contained in the alloy phase and the carbon material can be promoted to solid-dissolve carbon in the alloy phase, thereby joining the alloy phase and the carbon material. Furthermore, expensive materials such as gold and silver are not used in the intermediate material, making it possible to create a carbon material and copper material joint that is inexpensive, has excellent durability in high-temperature environments, and has sufficient joint strength.

[0020] The method for manufacturing a bonded body of a carbon material and a copper material according to the invention of claim 6 is characterized in that, in the invention of claim 5, the intermediate material is formed by laminating the phosphorus copper foil so as to sandwich the titanium foil from both sides. According to the above configuration, since the phosphorus copper foil exists on both sides of the titanium foil, the formation of the alloy phase of titanium and copper can be promoted.

[0021] The method for manufacturing a bonded body of a carbon material and a copper material according to the invention of claim 7 is a method for manufacturing a bonded body of a carbon material and a copper material, in which 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 are joined via an intermediate material. The intermediate material is formed by laminating a foil made of copper or a copper alloy and a stainless steel foil. With the carbon material sandwiching the foil made of copper or a copper alloy and the stainless steel foil pressurized in the lamination direction of the intermediate material, heating is performed in a non-oxidizing atmosphere by the electric heating method to a temperature below the melting point of the stainless steel foil, thereby forming an intermediate bonded body joining the carbon material and the intermediate material in a first bonding step. In a second bonding step, with the copper material adhered to the intermediate material side of the intermediate bonded body pressurized in the lamination direction, heating is performed in a non-oxidizing atmosphere by the electric heating method to a temperature below the melting point of the copper material, thereby joining the intermediate bonded body and the copper material.

[0022] According to the above configuration, an intermediate material obtained by laminating a copper or copper alloy foil and a stainless steel foil is joined to a carbon material 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 or copper alloy foil, and are heated to a temperature lower than the melting point of the stainless steel foil by an electric current heating method while being pressed in the lamination direction of the intermediate material. As a result, the copper or copper alloy foil, the stainless steel foil, and the carbon material, which are the intermediate materials, react with each other, and an intermediate joined body in which an intermediate material having an alloy phase in which iron and carbon are solid-dissolved in the copper matrix phase is joined to the carbon material is formed. In the second joining step, the copper material is heated to a temperature lower than the melting point of the copper material by an electric current heating method while being pressed so as to be in close contact with the intermediate material of the intermediate joined body. 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, which is inexpensive, has excellent durability in a high-temperature environment, and has sufficient joining strength, can be obtained.

[0023] The method for manufacturing a joined body of a carbon material and a copper material according to the invention of claim 8 is characterized in that, in the invention of claim 7, the thickness of the stainless steel foil is 0.05 mm to 0.2 mm. According to the above configuration, the residual stress after joining can be relaxed, and good thermal conductivity in the intermediate material can be maintained.

Effects of the Invention

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

Brief Description of the Drawings

[0025] [Figure 1] It is a view showing the inside of a fusion reactor. [Figure 2] It is a view showing a divertor plate installed inside the fusion reactor of FIG. 1. [Figure 3]This figure shows an example of a diverter plate constructed from a joint of carbon and copper materials according to the present invention. [Figure 4] This is an explanatory diagram of a carbon material using felt C / C composite. [Figure 5] This is an explanatory diagram of a carbon material using 1D-C / C composite. [Figure 6] This is a diagram showing the configuration of the pulse current pressurized sintering apparatus used to produce the carbon material and copper material joint of the present invention. [Figure 7] This is a perspective view of a test specimen formed by joining carbon and copper materials into a cylindrical shape. [Figure 8] This is an SEM image of the joint between the carbon material and the copper material in Example 2. [Figure 9] This is an SEM image of the joint between the carbon material and the copper material in Example 7. [Modes for carrying out the invention]

[0026] The following describes in detail embodiments for carrying out the present invention, but the present invention is not limited to the following embodiments.

[0027] As shown in Figures 1 and 2, a fusion reactor that confines high-temperature plasma is equipped with a divertor to remove excess gas and impurities, and multiple divertor plates A used in this divertor are mounted side by side. Diverter plates A serve as shielding members against the high-temperature plasma flow.

[0028] Diverter plate A is formed from a carbon material 1 and copper material 2 joint, which is made by joining a carbon material 1, which has excellent heat resistance and thermal conductivity and is used because it comes into contact with high-temperature plasma, to a copper material 2 that fixes the carbon material 1 and cools it. A refrigerant passage is provided through which cooling water, for example, flows as a refrigerant, passing through the inside of the copper material 2. The copper material 2 is cooled by the flow of refrigerant, which flows in from the inlet B of this refrigerant passage and out from the outlet C, and heat is transferred from the carbon material 1 to the copper material 2, thereby cooling the carbon material 1. This carbon material 1 and copper material 2 joint can also be applied to the first wall and protective limiter, which are plasma-facing devices in nuclear fusion reactors, and can also be applied as a heat sink in a heat treatment furnace. The shape and size can be set according to the application.

[0029] For carbon material 1, commercially available products such as artificial graphite or C / C composite (carbon fiber composite material) can be used. For copper material 2, pure copper, or commercially available chromium-containing copper alloys such as chromium copper (CuCr) or chromium zirconium copper (CuCrZr), which are easier to handle due to their higher hardness than pure copper, can be used.

[0030] The thickness of the carbon material 1 used in the divertor plate A of a nuclear fusion reactor is, for example, about 5 mm to 30 mm, but is not limited to this and can be determined appropriately depending on the application. Similarly, the thickness of the copper material 2 used in the divertor plate A is, for example, about 10 mm to 30 mm, but is not limited to this and can be determined appropriately depending on the application. Other dimensions besides the thickness of carbon material 1 and copper material 2 can also be set appropriately depending on the application.

[0031] Since carbon material 1 and copper material 2 have low reactivity and are difficult to join directly, an intermediate material 3 is interposed between carbon material 1 and copper material 2 for joining. Specifically, carbon material 1 and copper material 2 are pressed (compressed) so as to sandwich the intermediate material 3, and then heated to a temperature below the melting point of copper by an electrostatic heating method in a non-oxidizing atmosphere (vacuum or an inert gas atmosphere such as argon gas) to join them. The electrostatic heating method is a method in which an electric current is passed through a conductive object to be heated, and the object is directly heated by the Joule heat generated according to the electrical resistance of the object to be heated. At the same time, a high-temperature plasma state is generated in the gap between carbon material 1 and copper material 2 close to the intermediate material 3, and it is thought that the surrounding area melts, constructing a necking structure and joining the materials.

[0032] As an electrical heating method, Spark Plasma Sintering (SPS method) is preferred. In Spark Plasma Sintering, a pulsed current pressure sintering apparatus is used to heat the object to be heated by applying a large DC pulse current while pressurizing the object. Since Joule heat and a thermal plasma state are generated depending on the electrical resistance of the object to be heated, the heating temperature can be controlled by the current value, current application time, current application period, etc.

[0033] This section describes a cylindrical test specimen for evaluating a joint made of carbon material 1 and copper material 2. The carbon material 1 of the test specimen is made by processing artificial graphite or C / C composite into a cylindrical shape. As the C / C composite, a laminate in which multiple felt C / C composites are stacked in the direction of arrow D as shown in Figure 4, or a 1D-C / C composite in which the fiber axis direction of the carbon fibers is aligned in the direction of arrow E as shown in Figure 5, was 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 the direction in which heat is easily transferred, so for the felt C / C composite laminate it is perpendicular to the felt stacking direction shown by arrow D, and for the 1D-C / C composite it is set parallel to the fiber axis direction of the carbon fibers shown by arrow E.

[0034] Copper material 2 is a chromium-containing copper alloy processed into a cylindrical shape with a diameter of 9.5 mm and an axial length (thickness) of 10 mm. Intermediate material 3 is made by layering (laminating) titanium foil and phosphor copper foil, each processed into a circular shape with a diameter of 9.5 mm, or by layering (laminating) stainless steel foil (SUS316L foil) and copper foil, each processed into a circular shape with a diameter of 9.5 mm.

[0035] As shown in Figure 6, using a pulsed current pressurizing sintering apparatus 10, a carbon material 1 and a copper material 2 were placed on top of the object to be heated, with an intermediate material 3 sandwiched between them. By applying DC pulse current to the object to be heated while applying pressure, a cylindrical test specimen was formed, consisting of a carbon material 1 and a copper material 2, as shown in Figure 7.

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

[0037] The lower jig is equipped with a spacer 15 made of artificial graphite, which becomes smaller towards the punch 13 side. Similarly, the upper jig is equipped with a spacer 16 made of artificial graphite, which becomes smaller towards the punch 14 side.

[0038] The die 12 has an opening in the middle side portion, and the temperature of the object to be heated (heating temperature) is measured by a thermocouple 17 inserted into this opening. A 5 mm thick carbon felt (not shown) is fitted around the outer circumference of the die 12 for insulation. The casing 11 airtightly covers these upper and lower fixtures, the die 12, and a pair of punches 13 and 14.

[0039] The pulsed current pressurizing sintering apparatus 10 includes a pressurizing unit 18, a pulse power supply 19, a cooling mechanism 20, and a vacuum unit 21. The vacuum unit 21 maintains a vacuum state by exhausting the inside of the casing 11. The pressurizing unit 18 pressurizes the object to be heated via an upper jig, a lower jig, and punches 13 and 14. The pulse power supply 19 applies a DC pulse current to the object to be heated via the punches 13 and 14. The cooling mechanism 20 cools at least one pair of punches 13 and 14 by continuously circulating a coolant. Because heating is performed by the current heating method using this pulsed current pressurizing sintering apparatus 10, the carbon material 1, which has a higher electrical resistance than the copper material 2 and the intermediate material 3, generates more heat. Also, because the punches 13 and 14 are cooled, the copper material 2 does not rise to the heating temperature except for the portion on the intermediate material 3 side, so the copper material 2 is less likely to deform during joining.

[0040] Next, we will explain the evaluation of the test specimens. As shown in Figure 7, the cylindrical specimen has a joint between carbon material 1 and copper material 2 at its axial center. The shear strength of the joint was measured by applying stress to this specimen using an electronic universal testing machine (CATY-2002S, manufactured by Yonekura Seisakusho Co., Ltd.) in shear mode at a crosshead speed of 1 mm / min. A higher shear strength indicates a stronger joint. Furthermore, the joint portion of the specimen was analyzed using a scanning electron microscope (SEM) and an energy-dispersive X-ray spectrometer (JSM-IT200, manufactured by JEOL Ltd.).

[0041] Test specimens were prepared and evaluated for Examples 1-15 and Comparative Examples 1-4, each with different formation conditions (combination of carbon material 1, intermediate material 3, and copper material 2, heating temperature, heating time, and applied pressure). Examples 1-11 used phosphorus copper foil and titanium foil as intermediate material 3, while Examples 12-15 used copper foil and stainless steel foil as intermediate material 3. A pulse current pressurized sintering apparatus (model: SPS-515S, maximum load 50kN, maximum pulse current output 1500A) manufactured by Sumitomo Coal Mining Co., Ltd. was used to form the test specimens.

[0042] The heating conditions for the test specimens common to Examples 1-15 and Comparative Examples 1-4 are shown below. The atmosphere was set to a vacuum of approximately 20 Pa. The heating rate was set to 50°C / min to 100°C / min from room temperature to the heating temperature (maximum temperature). After the heating time (the time for maintaining the heating temperature) had elapsed, heating was stopped and the sample was allowed to cool naturally under vacuum. The cooling rate at this time was 30°C / min to 80°C / min. Once the temperature had dropped below 200°C, the sample was returned to atmospheric pressure and removed.

[0043] Table 1 shows the individual formation conditions for Examples 1-6 and Comparative Example 1, and the results of the bonding evaluation of the obtained test specimens. Carbon material 1 is artificial graphite (IG-430U manufactured by Toyo Tanso Co., Ltd., bulk density 1.82 g / cm³). 3 (Isotropic graphite) was used. For the intermediate material 3, phosphorus copper foil (BC-106 manufactured by Toyo Welding Materials Co., Ltd., an alloy foil of 94% copper and 6% phosphorus by mass, with a melting temperature of 705°C at the solidus line and 850°C at the liquidus line) and titanium foil (TR270C manufactured by Takeuchi Metal Foil Powder Industry Co., Ltd., 99.5% titanium by mass) were used. Since the melting point of phosphorus copper is around 700°C to 850°C, it is thought that a solid solution with titanium is formed at a temperature above this melting point, making joining possible at around 700°C to 850°C.

[0044] The thickness of the titanium foil suitable as intermediate material 3 is 0.01 mm to 0.5 mm, more preferably 0.05 mm to 0.3 mm, and even more preferably 0.05 mm to 0.15 mm. If the thickness is less than 0.01 mm, the amount of titanium is too small, making it difficult to obtain a good bond. If the thickness is greater than 0.5 mm, the intermediate layer 3a formed by the reaction of intermediate material 3 may become too thick, potentially reducing thermal conductivity. Similar to the titanium foil, the thickness of the phosphorus copper foil suitable as intermediate material 3 is 0.01 mm to 0.5 mm, more preferably 0.05 mm to 0.3 mm, and even more preferably 0.05 mm to 0.15 mm. In this study, a titanium foil with a thickness of 0.15 mm and a phosphorus copper foil with a thickness of 0.1 mm were used.

[0045] [Table 1]

[0046] Examples 1-6 and Comparative Example 1 all share the same carbon material 1 (artificial graphite) and copper material 2 (chromium zirconium copper). Test specimens were formed by varying the composition of the intermediate material 3, heating temperature, and heating time. The applied pressure was 40 MPa in all cases. It has also been confirmed that a similar joint of carbon material 1 and copper material 2 can be formed when copper material 2 is chromium copper or pure copper.

[0047] Examples 1-3 involved laminating a 0.1 mm thick phosphor copper foil as the intermediate material 3, sandwiching a 0.15 mm thick titanium foil from both sides, and heating at 920°C, 900°C, and 850°C, respectively, for 10 minutes. Example 4 involved laminating the intermediate material 3 so that the carbon material 1 side was a 0.1 mm thick phosphor copper foil and the copper material 2 side was a 0.15 mm thick titanium foil, and heating at 920°C for 10 minutes. Example 5 involved laminating the intermediate material 3 so that the carbon material 1 side was a 0.15 mm thick titanium foil and the copper material 2 side was a 0.1 mm thick phosphor copper foil, and heating at 920°C for 10 minutes. Example 6 used the same configuration of intermediate material 3 as Example 5 and heated at 920°C for 30 minutes. Comparative Example 1 used the same configuration of intermediate material 3 as Example 5 and heated at 830°C for 10 minutes.

[0048] Compared to Comparative Example 1, Examples 1 to 6 all exhibited higher shear strength, indicating a strong bond between the carbon material 1 and the copper material 2. According to Examples 1 to 3, higher heating temperatures resulted in higher shear strength, and in Examples 1 and 2, the carbon material 1 (artificial graphite) fractured without breaking at the joint.

[0049] In Examples 1 and 4, 5, where the heating conditions were the same, Example 1, which had a larger amount of phosphorus copper foil as the intermediate material 3, had a higher shear strength than Examples 4 and 5, and Examples 4 and 5 fractured at the interface between the carbon material 1 and the intermediate material 3. Also, the shear strength of Example 4, where phosphorus copper foil was placed on the carbon material 1 side, was higher than that of Example 5, where titanium foil was placed on the carbon material 1 side. Furthermore, in Examples 5 and 6, where titanium foil was placed on the carbon material 1 side, the shear strength of Example 6, which had a longer heating time, was higher than that of Example 5.

[0050] From the above results, it is possible to form a bonded carbon material 1 and copper material 2 by joining a carbon material 1 and copper material 2 made of artificial graphite using an intermediate material 3 consisting of phosphorus copper foil and titanium foil. In particular, by using an intermediate material 3 with a structure in which a 0.15 mm thick titanium foil is laminated between 0.1 mm thick phosphorus copper foil and heating it at a heating temperature of 850°C to 920°C for 10 minutes, a bonded carbon material 1 and copper material 2 with high shear strength can be efficiently formed. At this time, it is thought that the reaction between the molten phosphorus copper foil and titanium foil is promoted by phosphorus, and the reaction between the titanium solid-dissolved in the copper matrix and the carbon material is also promoted.

[0051] Table 2 shows the individual formation conditions for Examples 7-11 and Comparative Example 2, as well as the results of the bonding evaluation of the obtained test specimens. Here, as carbon material 1, felt C / C composite (TCC-123U manufactured by Toyo Tanso Co., Ltd., bulk density 1.49 g / cm³) was used. 3 ), or 1D-C / C composite (MFC-1 manufactured by Mitsubishi Chemical Corporation, bulk density 1.96 g / cm³) 3 The copper material 2 and the intermediate material 3, consisting of phosphorus copper foil and titanium foil, are the same as those used in Example 1, etc.

[0052] [Table 2]

[0053] Examples 7-11 and Comparative Example 2 all share the same configuration: carbon material 1 is a C / C composite, copper material 2 is chromium zirconium copper, and intermediate material 3 is a laminated structure consisting of 0.1 mm thick phosphorus copper foil sandwiching a 0.15 mm thick titanium foil. Test specimens were formed by varying the heating temperature. The C / C composites in Examples 7-10 and Comparative Example 2 are felt C / C composites, while only Example 11 uses a 1D-C / C composite.

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

[0055] Compared to Comparative Example 2, which had the lowest heating temperature, Examples 7-11 all showed high shear strength, indicating that the carbon material 1 and copper material 2 were firmly bonded. According to Examples 7-10, the higher the heating temperature, the higher the shear strength, and the carbon material 1 (felt C / C composite) fractured without breaking at the joint. In Example 11, although the shear strength was higher than in Examples 7-10 because the carbon material 1 (1D-C / C composite) was less likely to fracture in the direction that would cut the carbon fibers, it fractured at the interface between the carbon material 1 and the intermediate material 3.

[0056] Based on these results, it is possible to efficiently form a bond between carbon material 1 and copper material 2 with high shear strength by using a carbon material 1 made of C / C composite and an intermediate material 3 consisting of a 0.1 mm thick phosphor copper foil sandwiching a 0.15 mm thick titanium foil, and heating it at a heating temperature of 800°C to 920°C for 10 minutes.

[0057] Figures 8 and 9 show SEM images of the joint between carbon material 1 and copper material 2 for Examples 2 and 7. Between the dark-looking carbon material 1 and the bright-looking copper material 2, an intermediate layer 3a, slightly darker than the copper material 2, was observed, formed by the reaction of intermediate material 3. Elemental analysis revealed that each intermediate layer 3a contained carbon, phosphorus, titanium, chromium, and copper. Since carbon and chromium originate from carbon material 1 and copper material 2, respectively, intermediate material 3, consisting of phosphorus copper foil and titanium foil, reacts with carbon material 1 and copper material 2 to form intermediate layer 3a, and carbon material 1 and copper material 2 are joined via this intermediate layer 3a.

[0058] Furthermore, a region with a high titanium content (a bright area between carbon material 1 and intermediate layer 3a) was formed near the interface between intermediate layer 3a and carbon material 1. Although it varied depending on the analysis site, most of intermediate layer 3a contained approximately 60 atom / mol% to 80 atom / mol% copper and 10 atom / mol% to 30 atom / mol% titanium. On the other hand, in the region with a high titanium content, the copper content was approximately 10 atom / mol% to 40 atom / mol% and the titanium content was approximately 40 atom / mol% to 60 atom / mol%. The region with a high titanium content also tended to have a high phosphorus content. It is thought that the reaction between carbon material 1 (carbon) and titanium was promoted near the interface between intermediate layer 3a and carbon material 1, resulting in a strong bond. Furthermore, an alloy phase containing at least titanium, copper, and phosphorus is observed inside the carbon material 1, and it is thought that a portion of the intermediate layer 3a has entered the voids in the carbon material 1, reinforcing the bond between the carbon material 1 and the intermediate layer 3a.

[0059] Table 3 shows the individual formation conditions for Examples 12-15 and Comparative Examples 3 and 4, and the results of the bonding evaluation of the obtained test specimens. For carbon material 1, the above-mentioned artificial graphite or felt C / C composite was used, and for copper material 2, chromium copper or chromium zirconium copper was used. For intermediate material 3, a layer of commercially available copper foil and stainless steel foil (SUS316L foil) was used. These copper foil and stainless steel foil react with carbon material 1 to form a solid solution of iron and carbon in the copper matrix, creating an intermediate layer 3a containing an alloy phase composed of Fe-Cu-C. This intermediate layer 3a is strongly bonded to carbon material 1.

[0060] The preferred thickness of the stainless steel foil as 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 in the carbon material 1 becomes large, making it difficult to obtain sufficient bonding strength. If the thickness exceeds 1.0 mm, the thermal conductivity tends to decrease, which is undesirable. Although iron foil can be used instead of stainless steel foil, stainless steel foil is preferred because it has a lower melting point and can be bonded at a lower temperature.

[0061] The preferred thickness of the copper foil or copper alloy foil used 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 the thickness is less than 0.01 mm, there is too little copper and sufficient bonding strength cannot be obtained, and if it exceeds 0.5 mm, there is too much copper and bonding is easily inhibited. Copper alloy foil may be used instead of copper foil, and the type of copper alloy foil is not particularly limited; phosphorus copper foil can be used.

[0062] [Table 3]

[0063] Examples 12-15 and Comparative Examples 3 and 4 used a laminate of stainless steel foil and copper foil as the intermediate material 3, and test specimens were formed by changing the composition of the intermediate material 3, the types of carbon material 1 and copper material 2, and the heating conditions. Prior studies showed that a temperature of approximately the melting point of copper (1085°C) was necessary to promote the reaction between the intermediate material 3 containing stainless steel foil and the carbon material 1. Therefore, in order to avoid deformation of the copper material 2, a joint of carbon material 1 and copper material 2 was formed by two steps: a first joining step in which the carbon material 1 and intermediate material 3 were first joined at a high temperature to form an intermediate joint, and a second joining step in which the copper material 2 was joined to the intermediate material 3 side of this intermediate joint at a lower temperature than the first joining step. The heating time in the first joining step was 10 minutes, and the heating temperature in the second joining step was 900°C and the heating time was 10 minutes.

[0064] In Example 12, artificial graphite was used as the carbon material 1, and a 0.15 mm thick stainless steel foil was placed on top of a 0.01 mm thick copper foil placed on the carbon material 1 side as the intermediate material 3. In the first joining process, an intermediate joint was formed with a pressure of 10 MPa and a heating temperature of 1100°C. Then, in the second joining process, the chromium copper of the copper material 2 and the intermediate joint were joined with a pressure of 20 MPa.

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

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

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

[0068] Comparative Example 3 used artificial graphite as the carbon material 1, and as the intermediate material 3, a 0.05 mm thick stainless steel foil was placed on top of a 0.01 mm thick copper foil placed on the carbon material 1 side, and an intermediate joint was formed under the same heating conditions as in Example 12. In this intermediate joint, cracks occurred in the carbon material 1, and the joint between the carbon material 1 and the copper material 2 was not formed. It is thought that because the stainless steel foil was thinner (less stainless steel foil was used) than in Example 12, the residual stress when the intermediate joint was formed could not be fully relieved, and cracks occurred in the carbon material 1. In Example 15, the thickness of the stainless steel foil was also 0.05 mm, but it is thought that the carbon material 1 did not break because felt C / C composite was used as the carbon material 1, which has lower rigidity than artificial graphite and therefore relieves stress.

[0069] Comparative Example 4 used the same carbon material 1 and intermediate material 3 as in Example 13, and was heated under the same conditions as in Example 13, except that the heating temperature in the first joining step was 1050°C. However, the carbon material 1 and intermediate material 3 were not joined, and an intermediate joint could not be formed, thus failing to form a joint between the carbon material 1 and the copper material 2.

[0070] Examples 12-14 achieved a bonding strength comparable to Examples 1-6, which used artificial graphite as carbon material 1. Furthermore, in Examples 12-14, carbon material 1 fractured, resulting in a strong bond between carbon material 1 and copper material 2. Example 15 showed lower bonding strength than Examples 7-10, which used felt C / C composite as carbon material 1, but also showed a strong bond between carbon material 1 and copper material 2 due to the fracture of carbon material 1.

[0071] From the above results, by using an intermediate material 3 consisting of laminated copper foil and stainless steel foil (SUS316L), and in the first joining step, heating at a heating temperature of 1100°C to 1200°C for 10 minutes to form an intermediate joint, and in the second joining step, heating at a heating temperature of 900°C for 10 minutes to join the intermediate joint and the copper material 2, a joint of carbon material 1 and copper material 2 with high shear strength can be formed.

[0072] The thickness of titanium foil, phosphorus copper foil, stainless steel foil, and copper foil is not limited to those mentioned above. It can be set to ensure sufficient bonding strength, taking into account that the thermal conductivity between carbon material 1 and copper material 2 decreases as the thickness of the intermediate layer 3a increases. The pressing force during bonding was set to 5 MPa to 40 MPa, but any pressure that does not damage carbon material 1 and copper material 2 should be set. For example, depending on the thickness of the foil and heating conditions, a portion of the titanium foil or stainless steel foil may remain in a layered state. Even in this case, the titanium or iron dissolved in the copper matrix of the intermediate layer 3a will firmly bond it to the carbon material 1.

[0073] When manufacturing a joint of carbon material 1 and copper material 2 for use in diverter plate A, etc., the carbon material 1 and copper material 2 should be joined using materials, jigs, and a pulse current pressure sintering apparatus that are sized to match the joint. The time for maintaining the heating temperature (heating time) should be set according to the size of the object to be heated, but from the viewpoint of joint strength and productivity, it is preferably 5 to 60 minutes. Furthermore, those skilled in the art can implement the present invention in various forms with modifications to the above embodiments without departing from the spirit of the present invention, and the present invention encompasses such modifications. [Explanation of Symbols]

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

Claims

1. In a carbon material-copper joint formed by joining a carbon material made of artificial graphite or carbon fiber reinforced carbon composite material with a copper material made of pure copper or chromium-containing copper alloy, A carbon material and copper material bond, characterized in that it has an intermediate layer between the carbon material and the copper material in which titanium, phosphorus, and carbon are solid-solved in the copper matrix.

2. The carbon material and copper material bond according to claim 1, characterized in that the intermediate layer has a region with a high titanium content near the interface with the carbon material.

3. In a carbon material-copper joint formed by joining a carbon material made of artificial graphite or carbon fiber reinforced carbon composite material with a copper material made of pure copper or chromium-containing copper alloy, A carbon material and copper material bond, characterized in that it has an intermediate layer between the carbon material and the copper material in which iron and carbon are solid-solved in the copper matrix.

4. The carbon material and copper material joint according to any one of claims 1 to 3, characterized in that the copper material has a refrigerant passage formed therein for circulating a refrigerant.

5. In a method for manufacturing a carbon material and copper material joint, in which a carbon material made of artificial graphite or carbon fiber reinforced carbon composite material and a copper material made of pure copper or chromium-containing copper alloy are joined via an intermediate material, The aforementioned intermediate material is made by laminating titanium foil and phosphor copper foil. A method for manufacturing a carbon material and copper material bond, characterized in that the carbon material and copper material, which sandwich the intermediate material in the lamination direction, are pressed in the lamination direction, and heated to a temperature below the melting point of the copper material in a non-oxidizing atmosphere by an electric heating method, thereby joining the carbon material and the copper material.

6. The method for manufacturing a carbon material and copper material joint according to claim 5, characterized in that the intermediate material is formed by laminating the phosphor copper foil so that the titanium foil is sandwiched between the phosphor copper foil on both sides.

7. In a method for manufacturing a carbon material and copper material joint, in which a carbon material made of artificial graphite or carbon fiber reinforced carbon composite material and a copper material made of pure copper or chromium-containing copper alloy are joined via an intermediate material, The aforementioned intermediate material is made by laminating a copper or copper alloy foil with a stainless steel foil. A first joining step involves forming an intermediate joint by joining the carbon material and the intermediate material, while pressing the carbon material and the stainless steel foil, which sandwich the copper or copper alloy foil, in the lamination direction of the intermediate material, and heating them to a temperature below the melting point of the stainless steel foil in a non-oxidizing atmosphere by an electric heating method. A method for manufacturing a carbon material and copper material bond, characterized by having a second bonding step in which the intermediate bond and the copper material are bonded by heating the intermediate bond to a temperature below the melting point of the copper material in a non-oxidizing atmosphere using an electric heating method while the intermediate bond is pressed in the lamination direction so as to bring the copper material into close contact with the intermediate material side of the intermediate bond.

8. The method for manufacturing a carbon material and copper material bond according to claim 7, characterized in that the thickness of the stainless steel foil is 0.05 mm to 0.2 mm.

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