JPH06107463A - Unidirectional reinforced c/c composite material - Google Patents

Abstract

PURPOSE:To produce a unidirectional reinforced C/C composite material excellent in characteristics such as heat conductivity and strength in a direction perpendicular to carbon fibers. CONSTITUTION:Bundles of carbon fibers and bundles of org. fibers are arranged in one direction and a carbon matrix is impregnated into the resulting formed body to produce the objective unidirectional reinforced C/C composite material contg. <=60vol.% carbon fibers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a unidirectionally reinforced C / C composite material used in fusion reactor wall materials, high temperature furnaces and other high temperature fields, and a method for producing the same.

[0002]

2. Description of the Related Art Carbon fiber reinforced carbon composite materials (C / C composite materials) include unidirectional reinforcing materials, 2D materials in which fibers are two-dimensionally arranged in XY directions, and fibers are three-dimensionally arranged in XYZ directions. There is a 3D material. Among these, the manufacturing method of unidirectional reinforcement is
The following two methods are mainly known. A method in which commercially available unidirectional prepreg sheets are laminated with the fibers oriented in the same direction, the resin is cured, carbonized, and further impregnated with a carbon matrix (Reference example: Journal of the Japan Society of Mechanical Engineers, Volume 10, No. 2, P. 56,
"Current status of C / C composite development"). A method in which carbon fiber bundles are aligned in one direction by a filament winding method, wound around a plate or the like, and impregnated with a carbon matrix (reference example: carbon No. 115, "carbon fiber reinforced carbon composite material").

[0003]

In the unidirectionally reinforced C / C composite material obtained by the conventional method, the fibers are oriented in one direction as compared with the 2D material and the 3D material. Although the conductivity is remarkably improved, there is a problem that properties such as strength (interlaminar shear strength) in the other direction, that is, the direction perpendicular to the fiber, thermal conductivity, etc. are remarkably lowered. The present invention provides a unidirectionally reinforced C / C composite material having excellent properties such as strength and thermal conductivity in the direction perpendicular to the fiber, and a method for producing the same.

[0004]

Means for Solving the Problems As a result of studying conventional unidirectional reinforcing materials, the inventors of the present invention are inferior in properties such as strength and thermal conductivity in the direction perpendicular to the fibers because of the volume ratio of carbon fibers. It was clarified that it was caused by high (60% or more). That is, since the carbon fiber itself has a low thermal conductivity in the radial direction, when the fiber volume ratio is high, the thermal conductivity in the direction perpendicular to the fiber is close to the thermal conductivity in the radial direction of the carbon fiber and is low. Further, when the volume ratio of the carbon fibers is high, the carbon matrix between the carbon fibers becomes insufficient and the interlayer strength becomes low.
From the above consideration, the present inventors have found that the problem of the conventional material can be solved by reducing the volume ratio of carbon fiber.

According to the present invention, a unidirectionally reinforced C / C composite material having a volume fraction of carbon fibers of 60% or less, a carbon fiber bundle and an organic fiber bundle are arranged in one direction, and the resulting molded body is impregnated with a carbon matrix. The present invention relates to a method for manufacturing a unidirectionally reinforced C / C composite material.

In the unidirectionally reinforced C / C composite material of the present invention, the volume fraction of carbon fiber is 60% or less. If it exceeds 60%, the interlaminar shear strength and the thermal conductivity in the direction perpendicular to the fiber cannot be increased. For that purpose, it is necessary to make the volume ratio of the carbon fiber 60% or less, but the high-performance carbon fiber having high strength, high elasticity and the like has a straight filament and a small volume, and the volume ratio of the carbon fiber is 60% or less. Is difficult to do. The volume ratio of the carbon fibers can be reduced by arranging the carbon fiber bundles and the organic fiber bundles in one direction, and impregnating the resulting molded body with a carbon matrix to carbonize the carbon fiber matrix. This is because most of the organic fibers disappear at the time of carbonization, and the portions become voids, and the volume ratio of the carbon fibers can be reduced by further impregnating the carbon matrix. Even if a small amount of the organic fiber is carbonized and remains, it is assimilated with the matrix and does not become carbon fiber.
C Does not affect the properties of the composite. The type of carbon fiber is not particularly limited, but high performance (high strength, high elasticity) carbon fiber is preferable in order to increase the strength and thermal conductivity in the fiber direction. The organic fiber is also not limited, but those having a low carbonization rate or those having a high carbonization rate and easily graphitizable with the carbon matrix are preferable. As such a material, there is a thermoplastic resin fiber. The carbon matrix is also not limited, but a pitch or a synthetic resin having a large carbonization rate is preferable, and pyrolytic graphite or the like can be used. The ratio of carbon fiber to organic fiber may be appropriately selected according to the purpose and application, and is not particularly limited.

[0007]

As described above, it is preferable to mix the carbon fiber molded body with the organic fiber, which is largely lost later, to reduce the volume ratio of the carbon fiber and to make it perpendicular to the fiber in the unidirectionally reinforced C / C composite material. It acts to increase the strength in the direction (interlaminar shear strength) and thermal conductivity. In the present invention, the strength and the thermal conductivity are taken as the representative examples of the characteristics, but the conductivity, the thermal expansion coefficient and other characteristics are naturally affected. Summarizing the entire characteristics, the present invention acts to reduce the anisotropy of the unidirectionally reinforced C / C composite material.

[0008]

EXAMPLES Examples of the present invention will be described below. Example 1 Pitch-based highly elastic carbon fiber bundle (modulus of elasticity 500 GPa, density 2.15 g / cm ³ , fiber diameter 10 μm, number of filaments 2)
000), polytetrafluoroethylene fiber (melting point 327 ° C., density 2.3 g / cm ³ , fiber diameter 20 μm, number of filaments 1
80) and aramid fibers (melting point 500 ° C or higher, density 1.
45 g / cm ³ , fiber diameter 12 μm, filament number 100
Three bundles (0 pieces) were simultaneously wound by filament winding on a plate having a width of 200 mm 2434 times and cut at one position to prepare a bundle in which 2434 bundles were mixed. This is passed through a pipe with an inner diameter of 40 mm and the carbon fiber volume ratio is 30%, the organic fiber volume ratio is 32.5%, and the total fiber volume ratio is 6
A 2.5% compact was obtained. The molded body was impregnated with molten pitch, and the pitch and the organic fibers were carbonized at a temperature up to 900 ° C. in an inert gas atmosphere for about 5 days. The pitch impregnation and carbonization steps were repeated 6 times, and after graphitization at 2800 ° C., a unidirectionally reinforced C / C composite material having a bulk density of 1.84 g / cm ³ and a carbon fiber volume ratio of 40% was obtained. The characteristics are shown in Table 1.

Example 2 The same pitch-based high-elasticity carbon fiber bundle as in Example 1 and Example 1
Two bundles of the same aramid fiber were simultaneously wound by filament winding on a plate having a width of 200 mm 3245 times, and the volume ratio of carbon fiber was 40% in the same manner as in Example 1.
Organic fiber volume ratio 28.7%, total fiber volume ratio 68.7
% Fiber molding was obtained. From this molded product, in the same manner as in Example 1, the bulk density was 1.84 g / cm ³ , and the carbon fiber volume ratio was 50.
% Unidirectionally reinforced C / C composite was obtained. The characteristics are shown in Table 1.

Example 3 Pitch-based highly elastic carbon fiber bundle (same as in Example 1, but with 6000 filaments) and vinylon fiber (melting point 50)
Two bundles having a temperature of 0 ° C. or higher, a density of 1.3 g / cm ³ , a fiber diameter of 14 μm, and a number of filaments of 1000) were simultaneously wound by filament winding on a plate having a width of 200 mm, 1353 times, and carbon fibers were prepared in the same manner as in Example 1. Volume ratio 50
%, Organic fiber volume ratio 14.3%, total fiber volume ratio 64.
A 3% fiber molding was obtained. From this molded product, in the same manner as in Example 1, the bulk density was 1.84 g / cm ³ , and the carbon fiber volume ratio was 60.
% Unidirectionally reinforced C / C composite was obtained. The characteristics are shown in Table 1.

Comparative Example 1 Only the same pitch-based high-elasticity carbon fiber bundle as in Example 3 was subjected to filament winding to form 162 on a 200 mm wide plate.
Winding 3 times, and carbon fiber volume ratio 6 in the same manner as in Example 1.
A 0% carbon fiber compact was obtained. Next, a unidirectionally reinforced C / C composite material having a bulk density of 1.91 g / cm ³ and a carbon fiber volume ratio of 70% was obtained from this molded body in the same manner as in Example 1. The characteristics are shown in Table 1.

COMPARATIVE EXAMPLE 2 Only the same pitch-based high-elasticity carbon fiber bundle as in Example 3 was put into a 200 mm wide plate by filament winding.
It was wound three times, and carbon fiber volume ratio was 5 in the same manner as in Example 1.
A 0% carbon fiber compact was obtained. Next, a unidirectionally reinforced C / C composite material was obtained from this molded body in the same manner as in Example 1. This C / C composite material had many cracks parallel to the fibers, and its properties could not be measured. Similarly, carbon fiber volume ratio 4
A 0% carbon fiber molded body was prepared and a C / C composite material was prepared in the same manner, but similarly, there were many cracks, and the characteristics could not be measured (Comparative Example 3).

[0013]

[Table 1]

As is clear from Table 1, the C / C composite material of Comparative Example using only the carbon fiber bundle had low interlaminar shear strength and thermal conductivity in the direction perpendicular to the fiber, or cracking occurred. It is shown that the C / C composite materials of the examples in which the organic fiber bundles are also used have high interlaminar shear strength and thermal conductivity in the direction perpendicular to the fibers.

[0015]

According to the conventional method, it was difficult to reduce the volume fraction of carbon fiber of the unidirectionally reinforced C / C composite material to 60% or less. However, according to the present invention, the carbon fiber bundle and the organic fiber bundle are By mixing and using, it is possible to freely reduce the carbon fiber volume ratio, increase the interlaminar shear strength of the unidirectionally reinforced C / C composite material, and increase the thermal conductivity in the direction perpendicular to the fiber, that is, anisotropic properties. You can reduce the sex.

Claims (2)

[Claims] 1. A unidirectionally reinforced C / C composite material having a volume fraction of carbon fibers of 60% or less. 2. The method for producing a unidirectionally reinforced C / C composite material according to claim 1, wherein the carbon fiber bundle and the organic fiber bundle are arranged in one direction, and the resulting molded body is impregnated with a carbon matrix.