JPH07187833A - Carbon fiber reinforced carbon composite material - Google Patents

Abstract

PURPOSE:To obtain a carbon fiber reinforced composite material having gradation of thermal conductivity and electric conductivity in one direction which is useful for walls of a first furnace of a nuclear fusion device by using a pitch- base carbon fiber having a specified composition, structure and diameter. CONSTITUTION:In this carbon fiber reinforced carbon composite material (C/C composite material), pitch-base carbon fibers are oriented substantially in the thickness direction. The carbon fiber has such a structure that the central part of the fiber has a laminar structure of folded or bent graphite mesh planes and that the center structure is larger than the outer structure. The ratio of the thermal conductivity in the perpendicular direction to the thickness to the thermal conductivity in the thickness direction exceeds 2, and the thermal conductivity in the thickness direction is >=7W/cm. deg.C. It is preferable that the pitch-base carbon fibers have >=15mum diameter. A metal substrate 3 substantially perpendicular to the thickness direction of the C/C composite material is joined with a brazing material 4 to the opposite surface of the composite body 2 to the plasma facing plane 6. Thus, wall of a first furnace disposed facing to plasma in a nuclear fusion device is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon fiber reinforced composite material which has excellent thermal properties and can be effectively used as a fusion reactor wall material.

[0002]

2. Description of the Related Art The first wall of a nuclear fusion device refers to all structures in the nuclear fusion device installed facing a plasma, such as a limiter, a diverter, a blanket and a part thereof. Since it is installed close to plasma, it is in a severe environment where it receives heat load and particle load from plasma. Especially, the limiter, the diverter, etc. are subjected to a high heat load, so that the heat load condition is severe. One of the materials used as the material of the first wall under such conditions is graphite. Graphite is an excellent low atomic number material from the viewpoint of plasma impurities, and also has high thermal shock resistance.

The most typical conventional first wall using graphite is a graphite tile fixed to a metal substrate using a fixing plate and a connecting material. When the graphite tile facing the plasma has heat input from the plasma, that amount of heat is transferred to the substrate by contact heat transfer and dissipated by thermal radiation. In this method, since the graphite tile and the substrate are only in contact with each other due to their mechanical coupling, the heat transfer characteristics of the contact portion cannot be said to be sufficient, and they can withstand a long time or high heat load. Tended to be poorly cooled.

[0004]

However, the above-mentioned two conventional first walls have the following problems. When a high heat load (for example, 2 km / cm ² × 3 seconds or 4 km / cm ² × 1 second or more) is applied to the first wall, the surface reaches a temperature of about 2800 ° C. or more, and the graphite tile The vapor pressure is about 10 ^-3 atmospheres or more, and the sublimation wear thickness from the surface of the graphite tile is several tens.
It becomes as large as about μm / s or more. As a result, there is a problem in that the amount of carbon atoms mixed in the plasma increases, which has a great adverse effect on the plasma in controlling impurities. There is also a problem that the wear of the graphite surface is increased and the life of the first wall is shortened.

[0005] In the existing nuclear fusion device, these problems are seldom given the above-mentioned high heat load to the first wall, so that the conventional first wall sufficiently fulfills its function. However, in order to further improve safety, and in future fusion devices, it is expected that a higher heat load than the present will be constantly applied to the first wall for a long time, so The first wall that solved the problem is desired.

Therefore, the present applicant has previously provided a carbon fiber reinforced carbon composite material in which the above problems are solved. For example, in Japanese Unexamined Patent Publication No. 2-30664, carbon fibers are substantially oriented in the thickness direction as a carbon fiber reinforced composite material particularly suitable for the first wall installed facing the plasma of a nuclear fusion device, We proposed a carbon fiber reinforced carbon composite material in which the ratio of the thermal conductivity in the thickness direction to the thermal conductivity in the direction perpendicular to the thickness direction is 2 or more and the thermal conductivity in the thickness direction is 3 W / cm · ° C or more. . However, there has been a demand for a carbon fiber reinforced carbon composite material having further improved thermal conductivity, and it has become difficult to say that the conventional material is sufficient.

[0007]

Therefore, as a result of further diligent studies, the inventors of the present invention provided a carbon fiber reinforced carbon composite material satisfying the above-mentioned requirements, and as a result, the internal structure of the carbon fiber was preferably a specific carbon fiber, preferably It was found that a carbon fiber reinforced carbon composite material having a remarkably improved thermal conductivity can be obtained by using a fiber having a fiber diameter of 15 μm or more, and completed the present invention.

[0008] That is, the gist of the present invention is that the central portion of the fiber is
A structure in which the graphite network surface is laminated is bent or folded, and pitch-based carbon fibers having a structure structure larger than that of the outer periphery are substantially oriented in the thickness direction, and the thickness is The carbon fiber reinforced carbon composite material has a ratio of the thermal conductivity in the thickness direction to the thermal conductivity in the direction perpendicular to the direction of 2 or more and the thermal conductivity in the thickness direction of 7 W / cm ° C. or more.

The present invention will be described in detail below. First, the carbon fiber reinforced composite material (C / C used in the present invention
In the composite material), carbon fibers having an internal structure as described below are substantially oriented in the thickness direction, and the ratio of the thermal conductivity in the thickness direction to the thermal conductivity in the direction perpendicular to the thickness direction is 2 or more. In addition, the thermal conductivity in the thickness direction is 7.0 W / cm · ° C. or higher.

The carbon fiber used in the present invention is characterized by using high-performance pitch-based carbon fiber having a high thermal conductivity particularly in the fiber axis direction. Specifically, the spinning pitch for obtaining the carbon fiber used in the present invention is not particularly limited as long as it is a molecular species that is easily oriented and forms an optically anisotropic carbon fiber. Absent.

As the carbonaceous raw material for obtaining the spinning pitch, for example, coal-based coal tar, coal tar pitch, coal liquefaction, petroleum-based heavy oil, tar, pitch, or a catalytic reaction of naphthalene or anthracene And the like. These carbonaceous raw materials include:
Impurities such as free carbon, undissolved coal, ash, and catalysts are contained, but these impurities are filtered, centrifuged,
Alternatively, it is desirable to remove in advance by a well-known method such as stationary sedimentation separation using a solvent.

[0012] In addition, for example, a method of subjecting the carbonaceous raw material to heat treatment and then extracting a soluble component with a specific solvent,
Alternatively, the pretreatment may be performed by a method such as hydrogenation treatment in the presence of a hydrogen donating solvent or hydrogen gas.
In the present invention, a carbonaceous raw material having an optically anisotropic structure of 40% or more, preferably 70% or more, more preferably 90% or more is suitable. Is usually 350 to 500 ° C., preferably 380 to 450 ° C., for 2 minutes to 50 hours, preferably 5 minutes to 5 hours under an atmosphere of an inert gas such as nitrogen, argon, steam or the like, or heat treatment under blowing. Sometimes.

The ratio of the optically anisotropic structure of the pitch in the present invention is a value obtained as the area ratio of the portion showing the optical anisotropy in the pitch sample under a polarization microscope at room temperature. Specifically, for example, a pitch sample crushed into a few mm square is embedded with a sample piece on almost the entire surface of a resin having a diameter of 2 cm according to a conventional method, the surface is polished, and then the entire surface is covered with a polarizing microscope. It is determined by observing under (100 magnification) and measuring the ratio of the area of the optically anisotropic portion to the total surface area of the sample.

Such mesophase pitch is spun by a known method to obtain pitch fibers. At this time, in order to promote the orientation of the pitch molecules in the fiber axis direction, the spinning should be performed under the condition that the viscosity of the pitch in the discharge hole of the nozzle is reduced within a range where yarn breakage or pulsation does not occur. Is preferred. During spinning, the fiber diameter of the pitch fiber obtained by adjusting the discharge speed and the take-up speed from the nozzle can be adjusted. The carbon fiber of the present invention has a fiber diameter of 5 μm or more, preferably 15 μm or more, particularly preferably 15 μm or more.
It is preferably 50 μm, more preferably 18 to 40 μm. In order to obtain a carbon fiber having such a specific fiber diameter, spinning may be performed by anticipating the shrinkage of the fiber diameter at the time of carbonization and graphitization to be 20 to 30% to obtain a pitch fiber.

The obtained pitch fibers are infusibilized to obtain infusibilized fibers. The infusibilization method is air, oxygen, ozone,
A method of heating in an oxidizing gas such as nitrogen dioxide, a method of immersing in an oxidizing liquid such as nitric acid, or the like, any known infusibilizing method can be used, but those infusibilizing conditions are:
In the subsequent carbonization or graphitization process, it is necessary to set the conditions such that only the central portion of the infusible fiber is melt carbonized, that is, only the outer peripheral portion of the pitch fiber is made infusible. For example, in the method of heating the pitch fibers in air to make them infusible, the heating conditions are set to a lower temperature and / or a shorter time than the usual infusibilization to make only the outer peripheral portions of the pitch fibers infusible. Alternatively, the infusibilization may be performed in an atmosphere having a weaker oxidizing property than air without changing the time and the temperature. The specific conditions differ depending on the type of raw material pitch, the diameter of the spun yarn, and the like, and therefore the conditions for making the outer peripheral portion of the pitch fiber infusible can be appropriately selected when actually used.

The obtained infusible fiber is fired in an inert gas such as nitrogen or argon gas at a temperature required for carbonization or graphitization to obtain a carbon fiber. In the process of carbonizing the infusibilized fiber, its central portion is not sufficiently infusibilized and therefore it is heat-melted, but since the outer peripheral portion is not melted, the central portion is liquid-phase carbonized and the outer peripheral portion is solid-phase carbonized. Follow the carbonization route. Generally, the physical properties and characteristics of carbon materials are from 10Å to 1
The structure of crystallites evaluated by a size of about 000Å and the aggregated crystallites, that is, from 0.1 μm to 1
It is dominated by the organizational structure evaluated at a size of about 00 μm (Sugio Ohtani, Yuzo Sanada, Fundamentals of Carbonization Engineering)
Ohmsha (1980) 130) compares liquid-phase carbonization with solid-phase carbonization. In liquid-phase carbonization, the mesophase is carbonized while rearranged in the molten state, so that both the graphite crystallite and the structure become large. . Therefore, the carbon fiber obtained in this study has a structure in which the central part of the fiber has a much larger texture structure than the outer peripheral part, and when fired at 3000 ° C. or higher, the graphite crystal also becomes large and the a-axis direction The spread of La reaches over 1000Å. Radial type, random type, onion type, and the like are known as the structure structure of high-modulus pitch-based carbon fiber, which is said to depend on the flow of pitch during spinning (Otani Sugiro et al., Carbon Fiber (Modern Editing (1983) 197), the carbon fiber obtained in this study has a structure of the central part as shown in FIG. 1 because the central part melts and carbonizes at the time of carbonization by using a specific insolubilizing condition. Larger than the outer circumference. The difference in graphite crystallinity between the central portion and the outer peripheral portion of the fiber can be confirmed by measuring the central portion and the outer peripheral portion of the fiber cross section by, for example, μ-Raman spectroscopy.

The structure of the central portion of the fiber produced by the liquid-phase carbonization has a cross section perpendicular to the longitudinal direction of the fiber in a scanning electron microscope, which is appropriately 4000 times to 10,000 times according to the fiber diameter. It can be confirmed by magnifying and observing. That is, a laminated tissue structure having a length of 0.4 to 2 μm or more is present in the center of the tissue by bending or folding, and the size of the tissue structure is the same as the size of the tissue structure in the outer periphery of the fiber. In comparison, the length or thickness of the laminated portion is twice or more on average.
In addition, the portion having a large tissue structure at the center of the tissue occupies 4 to 90% of the total area of the tissue cross section. Since ordinary carbon fibers follow a solid-state carbonization route, the rearrangement of atoms is suppressed, and the bent or folded tissue structure is fine. However, in the carbon fiber according to the present invention, since the central portion undergoes liquid carbonization in the carbonization step, the bending or folding structure of the carbon fiber central portion in the cross-sectional structure is much larger than the bending or folding structure of the carbon fiber outer peripheral portion. It has the structural feature.

Furthermore, this carbon fiber is 500 to 640.
00 filaments, preferably 2000 to 8000 filaments are bundled and twisted as needed, but it is important that the thermosetting resin uniformly penetrates into the bundle of fibers. For this reason, it is preferable to subject the carbon fiber bundle to a defibration treatment with steam and then to oxidize the surface to an appropriate degree because a C / C composite material having good mechanical strength can be obtained.

This defibration treatment is carried out mechanically by rubbing the carbon fiber bundles on a plurality of rollers or metal bars, or by contacting ultrasonic waves with carbon fibers in water, and air, oxygen, and dioxide. Either a method of chemically reacting with an oxidizing gas such as carbon or carbon dioxide at a temperature of 200 ° C. or more and 1800 ° C. or less for 1 minute or more and 5 hours or less is used.

As a method of oxidizing the surface to an appropriate degree, a method of contacting with an oxidizing gas such as air, ozone, fluorine, or chlorine gas, or a method in which a carbon fiber bundle is used as an anode and electricity is applied in an electrolytic solution to perform electrolysis There is a method of performing oxidation, and there is no restriction in performing either method. The defibration treatment and the surface oxidation treatment are performed to such an extent that the strength of the carbon fiber is hardly impaired. In particular, it is preferable that the thermosetting resin is permeated into the carbon fiber bundle almost uniformly.

The C / C composite material in the present invention is obtained by the following method. First, a long fiber of carbon fiber is impregnated with a thermosetting resin, and this is heated to be semi-cured. Examples of the thermosetting resin include phenol resin, furan resin, epoxy resin, unsaturated polyester resin, and the like, and phenol resin, particularly resol type phenol resin can be preferably used. These thermosetting resins are usually
It is dissolved and diluted with a solvent such as alcohols such as ethanol, hydrocarbons such as hexane or acetone.

The concentration of the thermosetting resin solution is usually 10
˜70 wt%, preferably 20 to 60 wt%. In addition, a curing agent such as a furan resin or an epoxy resin that requires a curing agent is also added to the solution, but the amount is appropriate for each resin. As a method of impregnating the thermosetting resin solution with the long fibers of the carbon fibers, a simple method such as impregnating the carbon fibers into the solution may be used. From the viewpoint of processing efficiency, the method of running in a mechanical manner is preferable. In addition, at this time, 10 to 50 in the tank filled with the solution.
It is preferable to apply an ultrasonic wave of about kHz because it is possible to prevent the influence of processing unevenness due to air bubbles between each single fiber and between weaves.

The carbon fiber impregnated with the thermosetting resin solution is subjected to heat treatment, for example, by passing it through a roller to remove excess solution. By the heat treatment, the thermosetting resin is semi-cured. The heat treatment conditions differ depending on the type of thermosetting resin used, but usually 5
At a temperature of 0 to 300 ° C., preferably 80 to 200 ° C.
The heat treatment is performed for 2 to 5 hours, preferably 0.2 to 2 hours. At this time, it is desirable to gradually raise the temperature to a predetermined temperature in order to avoid rapid desorption of the solvent from the thermosetting resin solution applied to the carbon fibers. Further, the heat treatment is preferably carried out by a method in which carbon fibers are continuously run in a heating furnace from the viewpoint of treatment efficiency.

Next, the obtained fiber / resin composite is cut longer than the thickness direction of the intended C / C composite material. This length is usually selected from a range slightly longer than the desired thickness of the target, for example, 15 to 300 mm. The cut composites are aligned in one direction so as to be substantially parallel to each other, and are heated and molded by applying pressure in a direction perpendicular to the length direction of the fibers.

For example, by using a funnel-shaped tool to supply the composite to the mold, the composite is aligned in the mold so as to be substantially parallel, and heated at a temperature required for curing the resin. A molded body is obtained by applying pressure in a direction perpendicular to the length direction of the fibers to cure the resin. After that, the molded body is put into a container, and the molded body is surrounded by a coke breeze. Then, the container is put into an electric furnace, and if necessary, N ₂
Under a gas flow, the temperature is raised to about 1000 ° C. and carbonized.

If necessary, it is further placed in a graphitization furnace,
Heat treatment is performed in an inert atmosphere to a temperature of 2000 ° C. or higher. Then, the obtained carbide or graphitized product was impregnated with a thermosetting resin such as petroleum-based, coal-based pitch or phenol resin, furan resin, or when the thermosetting resin was used, the resin was cured. Post carbonize.

At this time, the thermosetting resin is alcohol,
It is common to use the one dissolved in a solvent such as water, acetone or anthracene oil and adjusted to have an appropriate viscosity. In this case, the method of impregnating under pressure is preferably adopted. For example, the carbide or graphitized product of the molded body and pitch were placed in a low-pressure reaction vessel (autoclave) and heated in a vacuum to dissolve the pitch, and the carbide or graphitized product was immersed in the melt of the pitch. After that, N ₂ gas is introduced and the temperature is raised to about 550 to 600 ° C. under low pressure.

Thereafter, the densified product of carbide or graphitized product is taken out by cooling, and 100% of this is prepared by the same method as described above.
Carbonize to about 0 ° C and graphitize if necessary. By repeating the above-mentioned so-called densification method, a highly dense C / C composite material having a specific gravity of 1.6 or more is obtained. At this time, if the resin content or densification of the fiber / resin composite is insufficient, or if the rate of temperature increase during carbonization or graphitization is too high, the strength of the fiber in the direction perpendicular to the length direction becomes small, In some cases, it may cause destruction, so it is necessary to select appropriate conditions. Further, the higher the graphitization temperature, the higher the thermal conductivity is likely to be obtained.

The obtained C / C composite material is an anisotropic material having high heat conductivity and high electric conductivity in the thickness direction. The obtained C / C composite material can be wound around the periphery with long fibers or the like made of carbon fiber, depending on the purpose, in order to improve the strength in the direction perpendicular to the thickness direction, or C / C
A carbon material such as a composite material can be bound into a proper shape. In addition, the surfaces of a plurality of composite materials are bonded together by using a resin such as a phenol resin as a main component, which is again C / C.
It is also possible to raise the temperature of the composite material to about the temperature at which the composite material was finally processed and to bond a plurality of small pieces of the C / C composite material to each other to obtain a composite material of a desired size.

In the C / C composite material of the present invention, the ratio of the thermal conductivity in the thickness direction (11) to the perpendicular direction (2) is 2 or more, preferably 7 or more, and optimally 10 or more, and The thermal conductivity in the thickness direction (11) is 7 W / cm · ° C. or higher, more preferably 8 W / cm · ° C. or higher. For example, even if a substance heated to a high temperature is placed on one surface thereof, Has a high thermal conductivity, heat is easily transferred to the other surface, and the heated substance can be effectively cooled by bringing the portion into which cooling water has flowed into contact with the other surface. That is, it can be effectively used when a substance is cooled by heat exchange.

In the present invention, such a C / C composite material is used as a main constituent material of the first wall installed facing the plasma of the nuclear fusion device, and one surface substantially perpendicular to the thickness direction. Is placed facing the plasma. In the present invention, preferably, a metal is metallurgically bonded to one side substantially perpendicular to the thickness direction of the C / C composite material, or the metal is bonded or coupled by mechanical bonding. Joining is preferred.

Metals are, for example, Ti, Cu, Fe, N
It is general to select from i, Mo, Cr and the like or alloys mainly containing these. As an alloy system, for example, T
In the case of i, those containing Al, V, etc. are preferably used.
These metals are usually about 5 mm or less, preferably 0.
Although it is used as a thin plate having a thickness of 1 to 0.3 mm, a stainless steel plate having a thickness of about 50 mm or less can be used as a substrate directly or through the thin plate as an interleaving material.
The joining can be performed by a conventional method such as vacuum brazing, diffusion joining, HIP (hot isostatic press).

The C / C composite material in the present invention has high heat conductivity and electric conductivity in one direction in the thickness direction, and can effectively remove and conduct heat. Further, when the metal bonding is performed as described above, the thermal shock resistance is particularly high in the direction perpendicular to the thickness direction. Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[0034]

【Example】

Example 1 Coal tar pitch with 100% optical anisotropy was spun,
A 4000 filament bundle of pitch fibers having a diameter of 23.6 μm was produced. Then, put it in a firing furnace controlled at a heating rate of about 1 ° C./min, and put it in an air atmosphere at 385 ° C.
The temperature was raised to infusibilization treatment. Next, in an N ₂ gas atmosphere, 5
After pre-carbonization at 10 ° C., twisting was performed at 14 turns / m.

After further treating in N ₂ gas containing 60% steam at 1200 ° C. for about 1 minute, it was fired in argon gas at 1250 ° C. to obtain carbon fibers having a diameter of 19.2 μm. When the cross section of this carbon fiber was observed, the central portion (about 6 μm) had a folded structure. Further, this carbon fiber bundle was used as an anode for electrolytic oxidation treatment in an aqueous calcium chloride solution. The amount of electricity passed was 5 coulombs / g of carbon fiber. This long fiber bundle of carbon fibers is dipped in an ethanol solution of phenol resin, and then placed in a dryer to 70 ° C.
After removing the ethanol with, the temperature was raised to 100 ° C. or higher to semi-cure the phenol resin. Obtained fiber / resin composite (tow prepreg) (carbon fiber: resin = 62: 38)
(Weight ratio) was cut to a length of 50 mm. In this product, the fibers were solidified with resin and were rod-shaped and rigid. The cut composites were aligned in one direction in a mold so as to be parallel to each other, and filled in a shape larger than the size of the target C / C composite.

Then, a low pressure is applied at 80 ° C. for 2 hours for 1 hour.
The temperature was raised to about 220 ° C. in 4 minutes, and the temperature was maintained for 1 hour, followed by molding and curing. The dimension after molding is 265.3 x 2
It was 65.2 x 49.9. Next, this molded product was put in a container filled with coke breeze, covered with coke please, and the temperature was raised to 1000 ° C. over about 50 hours to carbonize the resin.

Then, the carbonized composite material and the solid pitch are put into an autoclave and heated to 250 ° C. in a depressurized state, and then N ₂ is added to make the atmosphere water pressure, and then the temperature is raised for 8 hours. After reaching 500 ℃ at
Hold at 500 ° C. for 5 hours. During heating, the pressure was kept constant using a valve attached to the autoclave.

The autoclave was cooled, the composite material was taken out, carbonized to 1000 ° C. in the same manner as carbonization of the molded product, and then graphitized at 2000 ° C. After that, the above autoclave treatment and the subsequent carbonization treatment (1000 ° C)
Was repeated 3 times and then graphitized at 3000 ° C. to obtain a C / C composite material. The bulk density of the obtained C / C composite was 1.91 g / cm ³ , and the thermal conductivity in the thickness direction (the same direction as the fiber axis) and the direction perpendicular thereto was measured by a laser flash method thermal constant measuring device (manufactured by Vacuum Riko). ). The thermal conductivity in the thickness direction was 8.16 W / cm · ° C, the thermal conductivity in the direction perpendicular to the thickness direction was 0.42 W / cm · ° C, and the ratio was 19.6.

Embodiment 2 FIG. 2 shows a first embodiment of the first wall of the nuclear fusion device according to the present invention. The first wall 1 is obtained by vacuum brazing the C / C composite material 2 obtained in Example 1 described later onto the substrate 3. That is, the stainless steel substrate 3 having a thickness of 10 mm
A 1 mm thick Ti plate is used as an interleaving material with copper brazing and is joined through the brazing portion 4. A cooling pipe 5 is directly attached to the substrate 3 in order to enhance the cooling effect. The plasma facing surface 6 of this figure is installed facing the plasma of the fusion device and is used as the first wall.

FIG. 3 shows a second embodiment of the present invention.
In this embodiment, the C / C composite material obtained in Example 1 was used to join a thin metal plate (7 ') (pure Ti plate) to one surface substantially perpendicular to the thickness direction. That is, Cu is deposited on a pure Ti slope 7 (melting point: about 1675 ° C.) with a thickness of about 1 mm.
A brazing material is placed, the C / C composite material is further placed on the brazing material, a weight of about 1 kg is placed thereon, the temperature is raised in a vacuum furnace for about 1 hour, and the temperature is maintained at about 1050 ° C. for 5 minutes. A C / C composite material was obtained, which was Ti-bonded via No. 4. Then, this C /
The metal thin plate 7 of C composite material is mechanically attached to the substrate 3 by bolts or the like.
(8: fixing plate, 9: connecting material). Also, the substrate 3
As in the case of the first aspect described above, a cooling pipe can be attached to (6: plasma facing surface).

FIG. 4 shows a third embodiment of the present invention.
In this embodiment, the C / C composite materials 2 and 2'obtained in Example 1 are used to join the periphery of the cooling pipe 5 via the vacuum brazing portion 4. The plasma facing surface 6 is installed facing the plasma of the fusion device and is used as the first wall. Furthermore, the present invention is not limited to the above embodiments unless it exceeds the gist.

[0042]

The C / C composite material according to the present invention has a large thermal conductivity in the thickness direction. Easily 7 W / cm.degree. C. or higher, especially 7.5-10 W / c according to the above-mentioned embodiment.
Since it is possible to obtain a material having a temperature of about m · ° C, it is effective when used particularly when one-way conduction of heat or electricity is required. For example, a heat exchange material or switch for heat removal or heat transfer. It can be used as a material. Particularly suitable for fusion reactors, the first wall of the present invention, even when exposed to a high heat load for a long time, the surface temperature, vapor pressure and sublimation wear are suppressed low, and excellent properties as the first wall. Have.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a cross-sectional shape of a carbon fiber used in the present invention.

FIG. 2 is a schematic view showing an embodiment of the present invention.

FIG. 3 is a schematic view showing an embodiment of the present invention.

FIG. 4 is a schematic diagram showing an embodiment of the present invention.

Claims (4)

[Claims] 1. A pitch-based carbon fiber, which has a structure in which a graphite network surface is laminated at the center of the fiber, is bent or folded, and has a structure larger than that of the outer periphery. Is oriented in the thickness direction, the ratio of the thermal conductivity in the thickness direction to the thermal conductivity in the direction perpendicular to the thickness direction is 2 or more, and the thermal conductivity in the thickness direction is 7 W / cm.
-Carbon fiber reinforced carbon composite material having a temperature of ℃ or higher. 2. The C / C composite material according to claim 1, wherein the pitch-based carbon fiber has a diameter of 15 μm or more. 3. The carbon fiber reinforced carbon composite material according to claim 1, wherein a metal is bonded to one surface of the carbon composite material substantially perpendicular to the thickness direction of the carbon composite material. 4. The carbon fiber-reinforced carbon composite material according to claim 1, wherein the carbon fiber-reinforced carbon composite material has a thickness substantially perpendicular to the thickness direction and a metal is bonded to one surface not facing plasma. The first reactor wall installed facing the plasma of the fusion device.