JP2001181062A - Carbon fiber-reinforced carbon composite material impregnated with resin and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin-impregnated C/C material which has a high elastic modulus, a high heat conductivity, a low electric resistivity, a low thermal expansion coefficient, a small gas transmittance and excellent physical natures, and to provide a method for producing the same. SOLUTION: This resin-impregnated C/C material is characterized by impregnating and curing a C/C material with a thermosetting resin, and having an elastic modulus of 60 to 110 GPa, a thermal expansion coefficient of -0.46 to -0.21×10-6/ deg.C, a heat conductivity of 2.5 to 6.0 W/mk, an electric resistivity of 25 to 60 μΩm, and a gas transmittance of 1 to 3×10-7 m2/sec. The method for producing the resin-impregnated C/C material comprises impregnating carbon fibers with a thermosetting resin, molding the obtained composite material, calcining and carbonizing the molded product in a non-oxidizing atmosphere, further graphitizing the first carbonized product to produce the C/C composite material as the substrate, impregnating the substrate with a thermosetting resin, and then thermally curing the impregnated product, and is characterized by adjusting the porosity of the C/C composite material to 5 to 25%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a high elastic modulus, a high thermal conductivity, a low electric resistivity and a small coefficient of thermal expansion. The present invention relates to a resin-impregnated carbon fiber reinforced carbon composite material (hereinafter also referred to as a “resin-impregnated C / C material”) suitably used as a structural member of the present invention and a method for producing the same.

[0002]

2. Description of the Related Art C / C materials have excellent specific strength and specific elastic modulus due to the compounding of carbon fibers, and also have the lightness, excellent heat resistance and chemical stability inherent to carbon materials. Applications used under severe high-temperature conditions, such as structural materials for aerospace equipment, high-temperature furnace materials, and various other materials for semiconductor manufacturing, such as crucibles, heaters, and furnace materials for pulling single crystals by the CZ method. Has been useful in the field.

[0003] Typical techniques for producing this C / C material include: (1) prepreg molding in which a woven fabric of carbon fibers impregnated with a thermosetting resin as a matrix is laminated and compression-molded into a predetermined shape by a press or the like. Calcining the body in a non-oxidizing atmosphere,
A method of graphitizing, (2) a method of forming a carbon fiber tow soaked in a thermosetting resin into a predetermined shape by a filament winding method, and similarly calcining and carbonizing the prepreg molded body, and a method of graphitizing, (3) A method of depositing pyrolytic carbon by CVD (chemical vapor deposition) in a preform structure of carbon fibers is known.

In order to obtain a large C / C material,
The method (1) is the most practical as an industrial means. However, when employing this method, a considerable amount of thermosetting resin is pressed out during compression molding, or volatile components contained in the thermosetting resin are volatilized in the process of firing and carbonizing the prepreg molded body, Due to shrinkage during firing carbonization and graphitization, the resulting microstructure of the C / C material has fine holes, which tend to be low density and low strength. Therefore, secondary densification treatment in which the pores of the material structure of the C / C material are forcibly impregnated with a thermosetting resin such as a carbonizable phenol resin or a furan resin, or a coal or petroleum pitch, and then fired. Is commonly done.

The performance of the obtained C / C material is affected by the bonding strength between the carbon fiber and the thermosetting resin, and the bonding strength is governed by the interface wettability between the carbon fiber and the thermosetting resin. Poor wettability makes it difficult to obtain a strong composite structure.

Therefore, a method of modifying the surface of carbon fiber to improve interfacial wettability is known. For example, Japanese Patent Application Laid-Open No. 3-115172 discloses a method in which a substance similar to a matrix binder is coated on the surface of carbon fiber. A production method using carbon fibers that have been coated and then heat-treated to form a thin graphite film,
JP-A-5-254936 discloses that the degree of surface roughening is 2.0 to 2.0.
Tensile modulus 40 tonf / mm ² (390 GPa) in the range of 3.0
The above carbon fiber is oxidized in a gas phase or a liquid layer, and the surface oxygen content by X-ray photoelectron spectroscopy is determined as O _1S / C _1S = 0.20 to 0.40.
A molding material for a carbon fiber reinforced carbon composite material, in which a matrix resin having a carbonization yield of 40% or more is impregnated and applied to the carbon fiber assembly described above.

On the other hand, since the matrix carbon portion of the C / C material has a small fracture brittleness, there is a problem that the matrix carbon is liable to drop out of the carbon fiber when a repeated load is applied.
In order to prevent this difficulty, a resin impregnated C / C material has been developed in which a C / C material is impregnated with a resin and cured. However, the impregnated resin has a drawback that its use in a high-temperature atmosphere is limited due to its low heat resistance. Japanese Patent Application Laid-Open No. 3-261661 discloses a method of impregnating and curing a liquid polyimide resin having relatively high heat resistance. It has been disclosed.

[0008]

Generally, the C / C material has a high rigidity, and the carbonized portion of the thermosetting resin constituting the matrix of the C / C material has a small fracture brittleness, so that the C / C material has a low toughness. There is a problem that resistance to deflection is reduced. Also, in the above-mentioned JP-A-3-261661, improvement in strength in a temperature range of 300 ° C. or less is simply achieved by using a polyimide resin having a relatively high heat-resistant temperature. It is intended and is not intended to improve resistance to torsion or deflection.

The inventors of the present invention have made intensive studies to solve the problems of the C / C material, and as a result,
When impregnating the fine pores generated in the material structure of the C material with the thermosetting resin and curing, and filling the pores with the cured resin,
It has been found that the physical properties of the resin-impregnated C / C material can be improved by specifying the pores of the C / C material, that is, the porosity.

The present invention has been developed based on this finding, and has as its object to provide a resin-impregnated C / C material having a high modulus of elasticity, a high thermal conductivity, a low electrical resistivity, and a small coefficient of thermal expansion. It is to provide a manufacturing method thereof.

[0011]

A resin-impregnated C / C material according to the present invention for achieving the above object is obtained by impregnating and curing a C / C material with a thermosetting resin, and has an elastic modulus of 60 to 60%. 110
GPa, coefficient of thermal expansion −0.46 to −0.21 × 10 ⁻⁶ /
° C, thermal conductivity 2.5 ~ 6.0W / mK, electrical resistivity 25
It is characterized in that it has physical properties of １〜３60 μΩm and gas permeability of 1-3 × 10 ⁻⁷ m ² / sec.

[0012] Further, the method of producing the C / C is obtained by impregnating a carbon fiber with a thermosetting resin, forming a composite, calcining and carbonizing in a non-oxidizing atmosphere, and further graphitizing the obtained primary fired body. In a method for producing a resin-impregnated C / C material in which a C composite is used as a base material and the base material is impregnated with a thermosetting resin and heat-cured, the porosity of the C / C composite is set in a range of 5 to 25%. The porosity of the C / C composite is adjusted by repeating the operation of re-impregnating the primary fired body with a thermosetting resin and firing and carbonizing in a non-oxidizing atmosphere, or by chemical vapor phase. It can be carried out by a method of depositing pyrolytic carbon in pores of the C / C composite by a permeation method (CVI method).

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The resin-impregnated C / C material of the present invention
/ C material is impregnated with a thermosetting resin in the pores and cured, and the pores of the C / C material are filled with the cured resin and have a dense structure. The C / C material is a composite material having excellent material strength, which is firmly bonded to matrix carbon using carbon fiber as a reinforcing material as a skeleton. However, the carbonaceous matrix is hard and brittle, so it has high rigidity, torsion and bending. And the resistance when these forces act is not sufficient.

The resin-impregnated C / C material of the present invention
The pores of the material are filled with thermosetting resin, and C /
The carbonaceous matrix of the C material and the skeleton portion of the carbon fiber are reinforced by a thermosetting resin having high elasticity, and the elastic modulus is improved, the structure is densified, the thermal expansion coefficient is small, the thermal conductivity and the electrical resistivity are improved. Is improved.

That is, specifically, the elastic modulus is 60 to 1
10 GPa, coefficient of thermal expansion -0.46 to -0.21 × 10 ^-6
/ ° C, thermal conductivity 2.5-6.0 W / mK, electrical resistivity 2
There is provided a resin-impregnated C / C material having well-balanced physical properties of 5 to 60 μΩm and gas permeability of 1 to 3 × 10 ⁻⁷ m ² / sec.

The resin impregnated C / C material of the present invention is obtained by impregnating carbon fiber with a thermosetting resin, forming a composite, calcining and carbonizing in a non-oxidizing atmosphere, and further graphitizing the obtained primary calcined body. The C / C composite prepared as described above is used as a base material, and the base material is impregnated with a thermosetting resin and then heated and cured.

C as a base material of the resin-impregnated C / C material of the present invention
As the / C material, a material prepared by a known method is used. In other words, the carbon fiber used as the reinforcing material, polyacrylonitrile-based, rayon-based, plain weave manufactured from various raw materials such as pitch-based, satin weave, twill weave and other woven fabrics, which are oriented in one-dimensional or multi-dimensional directions Fiber moldings, felts, tows, etc. are used, and these carbon fibers are immersed and coated with a thermosetting resin such as a phenol-based or furan-based resin with a residual carbon ratio of 50% by weight or more, such as phenol or furan, or tar or pitch. Impregnation by such means as above, and heat curing to produce a composite molded article.

Next, in a non-oxidizing atmosphere such as nitrogen or argon, at a temperature of 800 ° C. or more, preferably 1000 to 1
Firing and carbonizing at a temperature of 500 ° C. to obtain a primary fired body. The primary fired body obtained is 1600 to 30 in a non-oxidizing atmosphere.
It is graphitized at a temperature of 00C, preferably 2000-3000C to produce a C / C composite.

A resin-impregnated C / C material is produced by impregnating a thermosetting resin in the pores of the C / C composite as a base material and curing by heating. /
The method for producing the C material is to increase the porosity of the C / C composite by 5 to 25%.
Is adjusted within the range of That is, in the production process of the C / C composite, fine pores are generated in the structure of the C / C composite due to volatilization of volatile components in the matrix binder, carbonization, and shrinkage during the graphitization treatment.
When the pores are impregnated with a thermosetting resin and heat-cured, and the interior of the pores is filled with the cured resin, the pores are sufficiently filled to improve the physical properties. It is necessary to adjust the ratio in the range of 5 to 25%.

A method for impregnating a C / C composite with a thermosetting resin is as follows.
After decompressing the gas occluded in the pores of the C / C composite by reducing the pressure to 0 Pa or less, a thermosetting resin such as a phenol resin, an epoxy resin, or a furan resin is flowed into the container to reach 500 to It can be carried out by a method of impregnating under pressure of about 2000 KPa.

In this case, if the porosity of the C / C composite is less than 5%, it is difficult to efficiently fill the pores with the resin, while if it exceeds 25%, the resin is filled into the pores. Is insufficient, and the effect of improving the physical properties cannot be achieved. The impregnated thermosetting resin is cured by heating to a temperature of about 100 to 170 ° C., and the pores of the C / C composite are filled with the cured resin and densified to improve the physical properties.

The porosity of the C / C composite is adjusted by re-impregnating the prepared primary fired body with a thermosetting resin, and in a non-oxidizing atmosphere such as nitrogen or argon at a temperature of 800 ° C. or higher, preferably 1000 ° C. By repeatedly performing the operation of calcining and carbonizing at a temperature of １1500 ° C., the porosity can be controlled to a predetermined porosity. For the re-impregnation, for example, the primary fired body is put into a container, the pressure is reduced to 1300 Pa or less, and the gas occluded in the pores in the primary fired body is degassed. It is carried out by a method of impregnating by pressurizing to about 2000 KPa.

On the other hand, the method of depositing pyrolytic carbon is C / C
The complex was set in a CVD reactor and the reaction temperature was set to 12
00-1300 ° C, pressure inside the device is 1300-13000
Pa, source gas concentration is controlled to 5-20 vol%, C / C
This is to deposit pyrolytic carbon in the pores of the composite. Here, pyrolytic carbon is deposited using a hydrocarbon gas such as methane, propane, propylene, or benzene as a source gas and using argon, hydrogen, or the like as a carrier gas.

[0024]

Hereinafter, examples of the present invention will be described in comparison with comparative examples.

Examples 1 to 3 A phenol resin precondensate (residual carbon ratio: 50%) was applied to a polyacrylonitrile-based high-strength plain-woven carbon fiber woven fabric, sufficiently impregnated, and air-dried for 48 hours to prepare a prepreg sheet. Was prepared. Sixteen of these prepreg sheets are stacked and placed in a 200 × 200 mm mold, pressed for 5 hours under the conditions of a temperature of 110 ° C. and a pressure of 2 MPa to perform primary curing, and then heated to a temperature of 250 ° C. to be completely cured. A composite molded body was produced.

Next, the composite molded body was transferred to a firing furnace maintained in a nitrogen atmosphere, and was heated at a temperature rising rate of 5 ° C./hr to 1000 ° C.
, And kept for 5 hours to obtain a primary fired body by firing and carbonizing. Next, this primary fired body is placed in a closed container, and
After reducing the pressure to 00 Pa, a phenolic resin precondensate is injected, pressurized to 785 KPa and impregnated at room temperature, then taken out of the container and calcined at a rate of 10 ° C./hr at a temperature of 1000 ° C. for densification. did. The operation of re-impregnating the phenol resin, firing and carbonizing to densify was repeated several times.

Example 4 A primary fired body produced in the same manner as in Examples 1 to 3 was set in a reactor of a CVD apparatus of a high-frequency induction heating system.
Propane gas was used as a source gas, and hydrogen was used as a carrier gas, and the total gas flow rate was set to 1.0 dm ³ / min. In the CVI reaction, after heating to a temperature of 1200 ° C. in a vacuum furnace, hydrogen gas is introduced, and when the temperature in the furnace reaches 1200 ° C. again, a raw material gas is introduced at a concentration of 10 vol. Was deposited. At this time, the pressure in the furnace was controlled by a pressure controller so as to be 6600 Pa.

These phenolic resins are re-impregnated and calcined and carbonized, or a calcined body on which pyrolytic carbon is deposited is 2,000
The mixture was heated to ℃ and graphitized to produce C / C composites (200 × 200 × 4 mm) having different porosity. These C / C
The composite was placed in a closed container as a base material, and after reducing the pressure to 400 Pa, a phenol resin was injected, and the mixture was pressurized to 785 KPa and impregnated at room temperature. Then remove from the container, 17
Primary curing at 0 ° C, and further heating at 250 ° C for 24 hours to completely cure the phenolic resin and impregnate C / C
Lumber was manufactured.

The tensile strength, elastic modulus, coefficient of thermal expansion, coefficient of thermal conductivity, electrical resistivity, and gas permeability of the resin-impregnated C / C material manufactured as described above were measured by the following methods. The results are shown in Table 1 together with the porosity of the / C composite. Tensile strength: Test specimen 150 × 13 × according to ASTM D3039
4t mm, Rating section 7mm, Crosshead speed 1.3mm / min
It measured on condition of. Elastic modulus: Calculated from the slope of the initial linear portion in the load-strain curve obtained in the above tensile test. Coefficient of thermal expansion; Laser-interferometry (temperature range -40 to +85
° C). Thermal conductivity: measured by a laser flash method. Electric resistivity: Measured by a voltage drop method according to JIS R7202. Gas permeability: Measured by the differential pressure method according to JIS K7126.

Comparative Example 1 In the same manner as in the Example, a polyacrylonitrile-based high-strength type plain woven carbon fiber woven fabric was coated with a phenol resin initial condensate (residual carbon ratio: 50%), sufficiently impregnated, and air-dried for 48 hours. Thus, a prepreg sheet was prepared. Sixteen of these prepreg sheets are laminated and placed in a 200 × 200 mm mold, pressed at a temperature of 110 ° C. and a pressure of 2 MPa for 5 hours for primary curing, then heated to 250 ° C. to be completely cured, Carbon fiber reinforced plastic composite (CFRP)
Was prepared. The tensile strength, elastic modulus, coefficient of thermal expansion, thermal conductivity, electrical resistivity, and gas permeability of this CFRP were measured in the same manner as in the examples, and the results are shown in Table 1.

Comparative Example 2 A CFRP was produced in the same manner as in Comparative Example 1, and was further calcined and carbonized to produce a C / C material. The obtained C / C material was measured for tensile strength, elastic modulus, coefficient of thermal expansion, thermal conductivity, electrical resistivity, and gas permeability by the same method as in the example, and the results are shown in Table 1.

[0032]

[Table 1]

From the results shown in Table 1, the resin-impregnated C / C material of the embodiment in which the pores of the C / C composite having the specified porosity are filled with a thermosetting resin and densified, has a physical property of It can be seen that the properties are improved and the physical properties such as the elastic modulus, the thermal expansion coefficient, the thermal conductivity, the electric resistivity, and the gas permeability are provided in a well-balanced manner.

[0034]

As described above, the resin-impregnated C / C of the present invention is used.
According to the material, the pores of the C / C material are impregnated and cured with the thermosetting resin, the pores of the C / C material are filled with the cured resin, and the pores are formed into a dense structure. Then, the carbonaceous matrix of the C / C material and the skeleton portion of the carbon fiber are reinforced by a thermosetting resin having high elasticity, and the elastic modulus is improved, the structure is densified, the thermal expansion coefficient is small, and the thermal conductivity is low. Physical properties such as electrical resistivity and gas permeability are improved, and excellent resistance to torsion and bending is imparted. Therefore, it can be suitably used as a structural member such as a transfer table or arm of a semiconductor manufacturing apparatus or an arm of an industrial robot. Further, according to the manufacturing method, a resin-impregnated C / C material having such excellent physical properties can be manufactured.

Claims (3)

[Claims] 1. A carbon fiber reinforced carbon composite material impregnated with a thermosetting resin and cured to have an elastic modulus of 60 to 110 GPa and a thermal expansion coefficient of -0.46 to -0.21 × 10 ^-6 / ° C, thermal conductivity 2.5 ~ 6.0W / mK, electrical resistivity 25 ~ 60μΩ
m, a resin-impregnated carbon fiber reinforced carbon composite material having physical properties of 1-3 × 10 ⁻⁷ m ² / sec. 2. A C / C composite produced by impregnating a carbon fiber with a thermosetting resin to form a composite, calcining and carbonizing in a non-oxidizing atmosphere, and further graphitizing the obtained primary calcined body. In the method for producing a resin-impregnated carbon fiber reinforced carbon composite material in which a base material is impregnated with a thermosetting resin and heat-cured, the porosity of the C / C composite is adjusted to a range of 5 to 25%. A method for producing a resin-impregnated carbon fiber reinforced carbon composite material, comprising: 3. The operation of re-impregnating the primary fired body with a thermosetting resin and firing and carbonizing in a non-oxidizing atmosphere is repeated until the porosity of the C / C composite falls within the range of 5 to 25%. The method for producing a resin-impregnated carbon fiber reinforced carbon composite according to claim 2, wherein pyrolytic carbon is deposited in the pores of the C / C composite by a chemical vapor infiltration method (CVI method).