JP2529148B2 - Method for manufacturing carbon / carbon composite material - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a carbon / carbon composite material.

[0002]

2. Description of the Related Art Carbon / carbon composite materials are materials having unique properties such as high strength and high elastic modulus even at a high temperature of 1000 ° C. or higher and a small coefficient of thermal expansion. It is used as a sliding member as well as parts and furnace materials.

[0003]

However, in order to obtain good sliding characteristics, a plurality of types of fibers are used,
Since it is necessary to use a plurality of types of matrix, a process for producing a carbon / carbon composite material having good sliding properties by a simple method has not been developed, and the cost is high.

An object of the present invention is to solve the above problems, to produce a carbon / carbon composite material having good sliding properties, and to establish a simple production process for producing the same.

[0005]

That is, the present invention provides a carbon / carbon composite material primary material having a fiber volume content of 10 to 80%, a matrix volume content of 5 to 50%, and a void volume ratio of 20 to 90%. The molded body in a non-oxidizing atmosphere,
A method for producing a carbon / carbon composite material, which comprises performing a step of densifying at a temperature of at least 1000 to 3000 ° C. and a temperature lower than a primary heat treatment temperature after a temporary heat treatment at 1100 to 3000 ° C., and a fiber volume content of 10.
˜80%, matrix volume content of 5 to 50%, and void volume ratio of 20 to 90%, a carbon / carbon composite material primary compact in a non-oxidizing atmosphere at 1100 to 3000 ° C.
At least 1000 to 3 after temporary heat treatment in
Of a carbon / carbon composite material characterized by performing a step of densifying at 000 ° C. and a temperature lower than the primary heat treatment temperature, and further performing a heat treatment at 1000 to 3000 ° C. and a temperature lower than the primary heat treatment temperature in a non-oxidizing atmosphere. Regarding manufacturing method.

The method for producing the carbon / carbon composite material according to the present invention will be described in detail below.

In the present invention, the carbon / carbon composite material primary molded body is composed of carbon fibers or a carbon fiber precursor and a carbonaceous matrix, and before being completely densified in the manufacturing process of the carbon / carbon composite material. The state of.

The carbon / carbon composite primary molding used in the present invention has a fiber volume content of 20 to 70%, a matrix volume content of 5 to 50%, preferably 10 to 30%, and a void volume ratio of 20. ˜40%.

As the carbon fibers or carbon fiber precursors used for the carbon / carbon composite primary molding, pitch-based, polyacrylonitrile-based and rayon-based carbon fibers are also available.
Properly it can be mentioned those of the precursors, particularly pitch-based carbon fiber or a precursor thereof of, easily increasing the oxidation resistance, which is preferable.

Examples of the pitch-based carbon fiber precursor include pitch fiber, infusible fiber and carbonized fiber.

The pitch fiber is an average diameter of 5 to 10 obtained by melt spinning carbonaceous pitch by a known method.
The fibers are 0 μm, preferably 7 to 30 μm.

The carbonaceous pitch mentioned here is a coal-based or petroleum-based pitch having a softening point of usually 150 to 400 ° C, preferably 200 to 350 ° C. As the carbonaceous pitch, either an optically isotropic pitch or an anisotropic pitch can be used, but the content of the optically anisotropic phase is 60 to
An optically anisotropic pitch of 100% is particularly preferably used.

The infusibilized fiber is a fiber obtained by infusibilizing the pitch fiber. The infusibilizing treatment is usually performed at 50 to 400 ° C., preferably 100 to 3 in an oxidizing gas atmosphere.
It can be carried out at 50 ° C. Examples of the oxidizing gas include air, oxygen, nitrogen compounds, sulfur compounds, halogens,
Alternatively, a mixture thereof or the like can be used. The processing time is usually 10 minutes to 20 hours.

The carbonized fiber is a fiber obtained by further carbonizing the infusible fiber. The carbonization treatment is usually 350 to 800 ° C., preferably 400, in an inert gas atmosphere.
It is usually carried out at ˜700 ° C. for 10 minutes to 5 hours.

Pitch-based carbon fiber means infusible fiber or carbonized fiber at a higher temperature, specifically 1200 to 3
A fiber obtained by treating at 000 ° C. This is in a broad sense
It corresponds to graphitization of carbonization. This graphitization process
It is usually carried out at 1200 to 3000 ° C. for 1 second to 5 hours in an inert gas atmosphere.

The carbon fibers or their precursors are usually cut into a length of 5 mm to 100 cm, preferably 1 to 50 cm and deposited non-oriented, or a continuous carbon fiber bundle of 500 to 25,000 fibers. Is used. Further, a one-dimensional laminate, a two-dimensional woven fabric or a laminate thereof, a three-dimensional woven fabric, a mat-shaped molded product, a felt-shaped molded product such as a two-dimensional or three-dimensional molded product may be used.

The carbonaceous matrix refers to those obtained by heat treatment of an organic precursor and those obtained by vapor phase pyrolysis of hydrocarbons and the like. Organic precursors include thermoplastics and thermosets.

A typical example of the thermoplastic organic precursor is carbonaceous pitch. Carbonaceous pitch has a softening point of usually 150.
It is a coal-based or petroleum-based pitch having a temperature of up to 400 ° C, preferably 200 to 350 ° C. As the carbonaceous pitch, either an optically isotropic pitch or an anisotropic pitch can be used, but the content of the optically anisotropic phase is 60 to
An optically anisotropic pitch of 100% is particularly preferably used.

On the other hand, a typical example of the thermosetting organic precursor is a carbonizing resin, specifically, a carbonizing thermosetting resin such as phenol resin or furan resin.

The method for producing the primary molded body of the carbon / carbon composite material, which is the base material of the present invention, is not particularly limited, and a known method can be appropriately used.

When the thermoplastic organic precursor is used for the carbonaceous matrix, for example, it is obtained by impregnating a carbon fiber woven fabric or a molded product with carbonaceous pitch or the like and then carbonizing it under normal pressure, pressurization or press. To be Impregnation is achieved by heating and melting carbonaceous pitch or the like under vacuum or diluting it with a solvent. If necessary, the carbonaceous pitch may be infusibilized.

When a thermosetting organic precursor such as a phenol resin or a furan resin is used, it is impregnated with a carbon fiber woven fabric or a molded product, and then cured, and carbonized under normal pressure, pressure or press. It Impregnation is achieved by heating and melting the resin under vacuum or diluting it with a solvent.

When an organic precursor is used for the carbonaceous matrix, carbonization under atmospheric pressure is usually 400 to 3000 in an inert gas atmosphere such as argon, nitrogen or helium for both the thermoplastic organic precursor and the thermosetting organic precursor. It can be carried out by heating to ℃. Also, the carbide under pressure, usually 50~10000kg / cm ² by the inert gas, preferably 200~2000kg / cm ² two like lateral pressurized, 400
It can be carried out by heating to 3000 ° C. The above inert gas can be used as the pressure medium gas. In addition, carbonization under press is usually 10 to 500 kg by hot pressing.
It can be carried out by heating normally to 400 to 3000 ° C. under uniaxial pressure of / cm ² .

As another example of the method for producing the carbon / carbon composite primary molded body, CVI (CHEMICAL VAPOR INF) in which the void is deposited and filled with carbon by vapor phase decomposition
ILTRATION). When depositing carbon by CVI, hydrocarbons, preferably C1 to C6 hydrocarbons, specifically, methane, natural gas, propane, benzene and the like are used as the pyrolysis gas for obtaining carbon. The reaction conditions are a temperature of 900 to 1500 ° C. and a pressure of 0.1 to 760 Torr.

Among the above-mentioned methods for producing a primary molded body of carbon / carbon composite material, a method using an organic precursor as a carbonaceous matrix, particularly a method using carbonaceous pitch is preferable.

In the present invention, the above-mentioned carbon / carbon composite material primary compact is placed in a non-oxidizing atmosphere in the range of 1100 to 3000.
After the primary heat treatment at 0 ° C., the densification step is performed by a specific means at a temperature lower than the primary heat treatment temperature. Further, if desired, in a non-oxidizing atmosphere, 1000 to 3000
It is also possible to perform the step of heat treatment at a temperature of ℃ and lower than the primary heat treatment temperature. If the densification is performed at a temperature equal to or higher than the primary heat treatment temperature or further heat treatment is performed if desired, good sliding characteristics cannot be obtained.

The densification method, the carbon / carbon composite primary molded body to having been subjected to the primary heat treatment, the CVI
Pyrolysis temperature is 700 ~ 3000 ℃ and temperature of primary heat treatment
Densification at lower temperatures or carbonaceous pitch
After immersion, pressurize or press 500-1500
Densified at ℃ and lower than the primary heat treatment temperature
It is.

The heat treatment temperature or the heat treatment temperature in these densification steps must be lower than the primary heat treatment temperature. The temperature difference from the primary heat treatment temperature is preferably in the range of 50 to 1000 ° C, particularly preferably in the range of 100 to 800 ° C.

In the densification using CVI, for example, at least one kind of hydrocarbon such as methane, ethane, acetylene, propane, benzene or natural gas diluted with an inert gas or hydrogen is used as a raw material, and a fiber molded product is obtained. Pyrolytic carbon is deposited on. The thermal decomposition temperature is usually 700 to 3000 ° C, preferably 800 to 2500 ° C. The thermal decomposition pressure may be atmospheric pressure, but reduced pressure is preferable, and specifically, it is usually 0.5 to 100 Torr,
It is preferably about 0.5 to 50 Torr.

When forming a carbonaceous matrix using carbonaceous pitch as a starting material in densification, specifically, the softening point is usually 100 to 400 ° C., preferably 15
Coal or petroleum pitch having a temperature of 0 to 350 ° C. is used.

As the carbonaceous pitch, either an optically isotropic pitch or an anisotropic pitch can be used, but the optically anisotropic pitch has an optically anisotropic phase content of 60 to 100%. Are particularly preferably used. The carbonaceous pitch is impregnated in the fiber molding and then carbonized. Carbonization
Is performed under pressure or press. Under pressure carbonization is usually 50~10000kg / cm ² with an inert gas, preferably pressurized to 100 to 2,000 kg / cm ^2, 50
It is carried out at 0 to 1500 ° C. Also, carbonization under press is usually 10 to 500 kg / cm by hot pressing.
² , preferably under a pressure of 20-200 kg / cm ² , 5
It is carried out at 00 to 1500 ° C.

After densification, in a non-oxidizing atmosphere, 1
It is also possible to perform the step of heat treatment at 000 to 3000 ° C. and a temperature lower than the primary heat treatment temperature. In this case, the temperature difference from the primary heat treatment is 50 to 1000 ° C., especially 100 to 8
The range of 00 ° C is preferred.

[0033]

According to the present invention, a carbon / carbon composite material having good sliding characteristics can be manufactured by a simple method.

[0034]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1 Softening point 280 ° C., content of optically anisotropic phase 100 vol
% Of petroleum pitch was melt-spun to obtain pitch fibers having an average diameter of 13 μm. This pitch fiber is placed in an oxidizing atmosphere for 22
After infusibilizing treatment at 0 ° C. for 4 hours, N _{2 of} 760 mmHg
Diameter 10 by firing at 700 ° C in gas
Micron carbonized fiber was obtained. The carbonized fiber is chopped so that the length / diameter ratio becomes 15,000 (average), and an optically anisotropic pitch having a softening point of 280 ° C. is mixed in the mixture ratio of 50 parts by weight / 100 parts by weight. Thus, the mixture was impregnated in the vacuum container at 350 ° C. 12.5 kg of impregnated material
A hot pressing was performed at a temperature of 500 ° C. for 1 hour under a pressure of / cm ² to obtain a carbon / carbon composite material primary molded body. This was further subjected to primary heat treatment at 2000 ° C. for 1 hour under normal pressure in N ₂ gas to obtain a heat-treated product of carbon / carbon composite material primary compact.

The heat-treated product of the carbon / carbon composite primary molded body was further impregnated with pitch at 350 ° C. in a vacuum vessel, and the temperature was 800 ° C. and the pressure was 1000 kg / cm ^{2 in} an inert gas.
After carbonizing for 30 minutes in an inert atmosphere,
A carbon / carbon composite material was obtained by firing at 00 ° C. for 30 minutes.

When a sliding test was carried out on the obtained carbon / carbon composite material, it showed a stable friction coefficient at both low speed and high speed, and the difference in friction coefficient between low speed and high speed. Was relatively small.

Comparative Example 1 The heat-treated product of the carbon / carbon composite material primary compact of Example 1 was further impregnated with pitch at 350 ° C. in a vacuum vessel at a temperature of 80.
After carbonization treatment at 0 ° C. and a pressure of 1000 kg / cm ² for 30 minutes, the carbonization treatment was further performed at 2300 ° C. in an N ₂ gas atmosphere to obtain a carbon / carbon composite material. When a sliding test was conducted on the obtained carbon / carbon composite material, it showed a stable friction coefficient at low speeds, but at high speeds the friction coefficient increased and stable sliding characteristics could not be obtained. It was

Example 2 The carbonized fiber obtained in Example 1 had a length / diameter ratio of 1
Chop to 5,000 (average), and mix with it an optically anisotropic pitch with a softening point of 280 ° C at 350 ° C in a vacuum container so that the mixing ratio is 50 parts by weight / 100 parts by weight. Impregnated. The impregnated material is hot-pressed at 500 ° C. for 1 hour under a pressure of 12.5 kg / cm ² to obtain a carbon / carbon composite material primary molded body, and further, under normal pressure, 1700 ° C.
Was carbonized for 1 hour to obtain a heat-treated carbon / carbon composite material primary molded body.

The heat-treated product of the carbon / carbon composite primary molded body was further impregnated with pitch in a vacuum vessel at 350 ° C., carbonized at a temperature of 800 ° C. and a pressure of 1000 kg / cm ² for 30 minutes, and then in an inert atmosphere. A carbon / carbon composite material was obtained by firing at 1500 ° C. for 30 minutes.

When a sliding test was conducted on the obtained carbon / carbon composite material, it showed a stable friction coefficient at both low speed and high speed, and the difference in friction coefficient between low speed and high speed was It was relatively small.

Comparative Example 2 The heat treatment product of the carbon / carbon composite material primary molded body obtained in Example 1 was further impregnated with pitch at 350 ° C. in a vacuum vessel,
After carbonizing at a temperature of 800 ° C and a pressure of 1000 kg / cm ² for 30 minutes, this is carbonized at 2000 ° C for 30 minutes in an inert atmosphere.
It was calcined for a minute to obtain a carbon / carbon composite material.

When a sliding test of the obtained carbon / carbon composite material was carried out, it showed a stable friction coefficient at low speeds, but at high speeds the friction coefficient increased and stable sliding characteristics were obtained. I couldn't.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junzo Fujioka 1-1, Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries, Ltd. Technical Research Institute (72) Takeshi Suemitsu 1-1, Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries, Ltd. Technical Research Institute (56) Reference JP-A-2-283666 (JP, A)

Claims (2)

(57) [Claims] 1. A fiber volume content of 20 to 70 %, a matrix volume content of 5 to 50%, and a void volume ratio of 20 to 4.
After temporarily heat treating the carbon / carbon composite material primary compact having 0 % at 1100 to 3000 ° C. in a non-oxidizing atmosphere, CVI at a thermal decomposition temperature of 700 to 3000 ° C.
In addition, the process of densification at a temperature lower than the primary heat treatment temperature
After impregnation with carbonaceous pitch, pressurization or press
Of carbon / characterized in that the step of densifying is performed at a temperature of 500 to 1500 ° C. below the pressure and a temperature lower than the primary heat treatment temperature.
Manufacturing method of carbon composite material. 2. A fiber volume content of 20 to 70 %, a matrix volume content of 5 to 50%, and a void volume ratio of 20 to 4.
After temporarily heat treating the carbon / carbon composite material primary compact having 0 % at 1100 to 3000 ° C. in a non-oxidizing atmosphere, CVI at a thermal decomposition temperature of 700 to 3000 ° C.
In addition, the process of densification at a temperature lower than the primary heat treatment temperature
After impregnation with carbonaceous pitch, pressurization or press
Characterized by performing a densification step at a temperature of 500 to 1500 ° C. under a pressureless condition and a temperature lower than the primary heat treatment temperature, and further performing a heat treatment step at a temperature of 1000 to 3000 ° C. and a temperature lower than the primary heat treatment temperature in a non-oxidizing atmosphere. Carbon
Manufacturing method of carbon composite material.