JPH07100630B2 - Method for manufacturing carbon / carbon composite material - Google Patents

Description

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

Problems to be Solved by Conventional Techniques and Inventions Carbon / carbon composite materials are materials having unique properties such as maintaining high strength and high elastic modulus even at high temperatures of 1000 ° C. or higher and having a small coefficient of thermal expansion. Therefore, it is expected to be used for parts of aerospace equipment, brakes, furnace materials, etc. However, the manufacturing process for compositing the matrix and the carbon fiber is complicated and requires a long number of days, which is costly. The present invention provides a method for producing a carbon / carbon composite material by a simple method.

Means for Solving the Problems The present inventors have completed the present invention as a result of research to develop a simple manufacturing process that solves the above problems.

The present invention relates to (A) 5 to 50 parts by weight of carbonaceous pitch having a softening point of 150 to 400 ° C., (B) infusible fiber obtained by infusibilizing pitch fiber obtained by spinning carbonaceous pitch, and these. The infusible fiber of 350
20 to 95 parts by weight of one or two or more kinds of fibers selected from the group consisting of pre-carbonized fibers obtained by pre-carbonizing at ~ 800 ° C, and (C) 5 to 80 parts by weight of pitch-based carbon fibers are pressed. Or carbon characterized by carbonization under pressure /
The present invention relates to a method for manufacturing a carbonized composite material.

Hereinafter, the present invention will be described in detail.

In the present invention, (A) carbonaceous pitch has a softening point of 150 to 4
Coal-based or petroleum-based pitch having a temperature of 00 ° C, preferably 200 to 350 ° C. The carbonaceous pitch may be either an optically isotropic pitch or an anisotropic pitch, but the content of the optically anisotropic phase is 60 to 100 vol%, preferably
An optically anisotropic pitch of 80 to 100 vol% is particularly preferably used.

The (B) pitch fiber referred to in the present invention is a fiber having an average diameter of 5 to 100 μm, preferably 7 to 30 μm, obtained by melt-spinning the carbonaceous pitch by a known method. The infusible fiber in the present invention is a fiber obtained by infusibilizing the pitch fiber. The infusibilizing treatment can be carried out in an oxidizing gas atmosphere at 50 to 400 ° C, preferably 100 to 350 ° C. As oxidizing gas, air, oxygen,
Nitrogen oxide, sulfur oxide, halogen, or a mixture thereof can be used. The infusibilization treatment is usually performed for 10 minutes to 20 hours. On the other hand, the pre-carbonized fiber in the present invention means a fiber obtained by further pre-carbonizing the infusible fiber.
The pre-carbonization treatment is performed in an inert gas atmosphere at 350 to 800 ° C., preferably 400 to 700 ° C., and usually 10 minutes to 5 hours.

In the present invention, the (C) pitch-based carbon fiber means a fiber obtained by further carbonizing or graphitizing the pre-carbonized fiber. Carbonization is 700-200 in an inert gas atmosphere.
It is usually carried out at 0 ° C for 10 minutes to 5 hours. The graphitization process
It is usually carried out at 2000 to 3000 ° C. in an inert gas atmosphere for 1 second to 5 hours.

In the present invention, (A) 5 to 50 parts by weight of carbonaceous pitch,
Preferably 10 to 40 parts by weight, (B) one or more fibers selected from the group consisting of infusible fibers and pre-carbonized fibers 20 to 95 parts by weight, preferably 25 to 50 parts by weight, and (C) Pitch-based carbon fiber 5 to 80 parts by weight, preferably 10 to
Carbonize 70 parts by weight under pressure or under pressure.

Carbonization under pressing is performed by hot pressing in a non-oxidizing atmosphere, for example, in a vacuum or in an atmosphere of an inert gas such as nitrogen, argon or helium, at 5 to 500 kg / cm ² , preferably 1
It is carried out at 0 to 300 kg / cm ² , 400 to 2000 ° C., preferably 500 to 1500 ° C. Carbonization under pressure is 50% due to the inert gas.
~10000kg / cm ^2, preferably pressurized to 100~3000kg / cm ^2,
It is carried out at 400 to 2000 ° C, preferably 500 to 1500 ° C. The fibers can also be preformed at room temperature prior to carbonization under press or pressure.

After carbonization under pressure or under pressure, it may be carbonized or graphitized in a non-oxidizing atmosphere, for example, in a vacuum or normal pressure, or in an inert gas atmosphere at 400 to 3000 ° C, if necessary.

The reinforcing effect is insufficient only with the components (A) and (B), and the moldability is insufficient with only the components (B) and (C),
The aspect ratio of the reinforcing material component cannot be increased. Further, if only the components (A) and (C) are used, the fluidity becomes excessive at the time of molding, and the binder component flows out, leading to contamination of the carbonization equipment.

Examples of the method for compositing the three components (A), (B) and (C) include, for example, mixing and crushing or cutting these components, or individually crushing or cutting them and then mixing them, and then pressing or pressing. There is a method of carbonizing under pressure.
The mixed pulverization or cutting is performed at least to such an extent that the shape of the fiber is retained, and the l / d (aspest ratio) of each fiber is 2 to 5000, preferably 5 to 3000. Usually, the l / d of the infusibilized fiber or the pre-carbonized fiber is made smaller than the l / d of the pitch-based carbon fiber.

As another example, the two components (A) and (B) are mixed and crushed or cut, and the mixture is filled in or between the woven fabrics of pitch-based carbon fiber which is the (C) component, and both are pressed or pressed. There is a method of carbonizing under pressure.

EXAMPLES The present invention will be specifically described with reference to the following examples.

Example 1 (A) Petroleum-based pitch having an optical anisotropic phase of 100 vol% having a softening point of 280 ° C., (B) the petroleum-based pitch was melt-spun,
33 parts by weight of pitch fiber having an average diameter of 13 μm, three components of infusible fiber obtained by infusibilizing the pitch fiber in air at 240 ° C. and (C) pitch-based carbon fiber having an aspect ratio of 300, 33 parts by weight and 33 parts by weight are mixed, crushed, and hot pressed under a pressure of 100 kg / cm ^{2 to}
It was press carbonized at 000 ° C. for 30 minutes to produce a carbon / carbon composite material having a bulk density of 1.6 g / cc. The contamination in the hot press machine is extremely slight, and the porosity of the obtained material is 10%.
Was less than. Observation using a polarizing microscope or an electron microscope also revealed that the fiber structure was extremely uniformly distributed.

(Comparative Example 1) The infusible fiber of Example 1 was crushed, and 100 kg / cm by hot pressing together with pitch-based carbon fiber having an aspect ratio of 300.
^{It was} press carbonized at 1000 ° C. for 30 minutes under a pressure of ² to produce a material having a bulk density of 1.6 g / cc. The porosity of the obtained material is 1
Although it was less than 0%, the moldability was insufficient.

Comparative Example 2 The pitch-based carbon fiber of Example 1 was hot-pressed to 10
When press carbonization was carried out at 1000 ° C. for 30 minutes under a pressure of 0 kg / cm ² , the obtained product had poor moldability and could not be machined.

Comparative Example 3 When the pitch and pitch-based carbon fiber of Example 1 were press carbonized for 30 minutes at 1000 ° C. under a pressure of 100 kg / cm ² by hot pressing, the pitch flowed out and the molding could not be performed well. Also, the inside of the furnace was contaminated.

(Example 2) (A) a powder of petroleum-based pitch having an optical anisotropic phase of 100 vol% having a softening point of 280 ° C., (B) the petroleum-based pitch was melt-spun to obtain a pitch fiber having an average diameter of 13 μm. In the air
After infusibilizing treatment at 300 ° C. for 1 hour, it was treated at 400 ° C. for 1 hour in nitrogen to obtain a pre-carbonized fiber. This previous carbonized fiber tow 37.5
1 part by weight is pulverized into a fiber having an l / d of 10 and 37.5 parts by weight of the pulverized product of the pitch and (C) 25 parts by weight of a fiber having an l / d of 50 obtained by pulverizing the pitch-based carbon fiber. The mixture was mixed and press carbonized for 1 hour at 600 ° C. under a pressure of 100 kg / cm ² by hot pressing. This carbide was fired in a nitrogen atmosphere at 1200 ° C. for 30 minutes to produce a carbon fiber-containing material having a bulk density of 1.6 g / cc. The porosity of the obtained carbon material was less than 10%. Observation using a polarizing microscope or an electron microscope also revealed that the fiber structure was extremely uniformly distributed.

Example 3 A petroleum pitch having an optical anisotropic phase of 90 vol% and a softening point of 280 ° C. was melt-spun to obtain pitch fibers having an average diameter of 13 μm,
This was infusibilized in air at 300 ° C. for 1 hour to obtain infusibilized fiber. 25 parts by weight of the infusible fiber and 25 parts by weight of the pitch fiber are mixed and pulverized, and the mixture is filled between 50 parts by weight of a plain weave of pitch-based carbon fiber, and hot-pressed under a pressure of 50 kg / cm ² in a nitrogen atmosphere 1200 ℃ 30 minutes, bulk density 1.7g / cc
Was manufactured. The porosity of the obtained carbon material was less than 10%. Observation using a polarizing microscope or an electron microscope also revealed that the fiber structure was extremely uniformly distributed.

Example 4 Pitch fibers having an average diameter of 13 μm obtained by melt-spinning petroleum-based pitch having an optical anisotropic phase of 100 vol% having a softening point of 280 ° C. were infusibilized in air at 300 ° C. for 1 hour, 350 in nitrogen
A pre-carbonized fiber was obtained by treating at 1 ° C. for 1 hour. This pre-carbonized fiber tow was crushed to give a fiber having a l / d of 10, and 16 parts by weight of the crushed material of the pitch was mixed with 24 parts by weight of this fiber and filled between 60 parts by weight of a plain weave of pitch-based carbon fiber. Then put in a stainless steel container, under a pressure of 200 kg / cm ² , in a nitrogen atmosphere 1
A carbon fiber-containing material having a carbonized bulk density of 1.5 g / cc was produced at 000 ° C. for 30 minutes. The porosity of the obtained carbon material was less than 5%. Observation using a polarization microscope or an electron microscope also revealed that the fibrous tissue matrix was extremely uniformly distributed.

Claims (1)

[Claims] 1. An infusible fiber obtained by infusibilizing a pitch fiber obtained by spinning (A) a carbonaceous pitch having a softening point of 150 to 400 ° C., and (B) a carbonaceous pitch. These infusibilized fibers were further treated in an inert atmosphere at 35
20 to 95 parts by weight of one or more fibers selected from the group consisting of pre-carbonized fibers obtained by pre-carbonization at 0 to 800 ° C., and (C) 5 to 80 parts by weight of pitch-based carbon fiber are pressed. Carbon characterized by carbonization under pressure or under pressure /
Manufacturing method of carbonized composite material.