JPH0825815B2 - Method for producing carbon-carbon composite material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a carbon-carbon composite material.

Conventional technology and its problems Carbon-carbon composite materials (also referred to as C-C composites) have higher strength, superior heat resistance, wear resistance, and oxidation resistance than conventional carbon materials. Therefore, it is used as materials for aircraft brakes, rocket nozzles and other aircraft and aerospace equipment; hot press dies, mechanical parts such as high temperature bearings, biomaterials, etc.
Or it is about to be used.

A conventional carbon-carbon composite material is obtained, for example, by impregnating a carbon fiber precursor with a pitch or a thermosetting resin under pressure, firing, and repeating impregnation and firing a necessary number of times. There is. In this method, since the volatile component generated by the decomposition of the pitch or the thermosetting resin in the firing step forms bubbles, the complicated operation of impregnating the pitch portion or the thermosetting resin in the bubble portion and firing is repeated. There is a need. However, despite the need for such a complicated process, the product obtained is
It is porous and unsatisfactory in terms of density, and it has the drawback of lacking uniformity in large products.

Further, a method (CVD method) of decomposing a hydrocarbon gas in a high-temperature furnace and depositing decomposition products on the surface of carbon fibers is also performed. However, this method requires uniform thermal decomposition for a long time under the condition that soot is not generated, and requires a high level technique for setting the conditions, so that it is difficult to be practically used.

Means for Solving the Problems The present inventor has made extensive studies in view of the current state of the art as described above, and infusibilizes the pitch fibers before the infusibilization treatment in which the raw material pitch is spun, or the pitch fibers. The obtained infusible fibers as they are or by mixing these fibers with a caking component and a carbonaceous powder having self-sinterability,
It has been found that the problems of the prior art can be greatly reduced when molding, carbonizing and graphitizing.

That is, the present invention provides the following method for producing a carbon-carbon composite material by using at least one carbonaceous powder selected from the group consisting of infusibilized pitch fiber, mesocarbon microbeads, bulk mesophase crushed product, and low temperature calcined coke crushed product. And mixed,
A method for producing a carbon-carbon composite material, which comprises molding, carbonizing and graphitizing (hereinafter referred to as the first invention of the present application).

The first invention of the present application, wherein the carbonaceous powder is mesocarbon microbeads.

At least one selected from the group consisting of mesocarbon microbeads, bulk mesophase crushed products, and low temperature calcined coke crushed products after surface treatment of infusible pitch fibers with a material containing a caking component, washing with an organic solvent, and drying. A method for producing a carbon-carbon composite material, which comprises mixing two carbonaceous powders, molding, carbonizing and graphitizing (hereinafter referred to as the second invention of the present application).

The second invention of the present application in which the carbonaceous powder is mesocarbon microbeads.

The first invention and the second invention of the present application will be described below in detail. In the following, when simply referred to as “the present invention”, the items common to both inventions are shown.

I. First Invention of the Present Invention The raw material pitch used as the spinning material in the present invention may be derived from a raw material such as a coal-based or petroleum-based material. Also, the pitch itself may be either optically isotropic or optically anisotropic.

Spinning and infusibilization of the raw material pitch may be performed according to a conventional method, and the conditions are not particularly limited. What is used as a fiber component in the present invention is usually a pitch fiber obtained by supplying a raw material pitch to a spinning machine and extruding from a nozzle under pressure with an inert gas in a state of being heated to about 300 to 400 ° C, or Pitch fiber in an oxidizing atmosphere 150-500
It is an infusibilized fiber that has been infusibilized by being held at about 0 ° C. for about 0.5 to 5 hours before being subjected to the usual carbonization treatment (hereinafter, pitch fiber and infusibilized fiber are collectively referred to as uncarbonized fiber). The uncarbonized fiber preferably has a yarn length of about 0.01 to 30 mm and a yarn diameter of about 5 to 25 μm.

In the first invention of the present application, the uncarbonized fiber obtained as described above and the carbonaceous powder having self-sinterability are mixed as they are,
Mold, carbonize and graphitize.

The self-sintering carbonaceous powder used in the present invention may be either petroleum-based or coal-based, and specifically, mesocarbon microbeads, bulk mesophase pulverized products, low temperature calcined coke pulverized. Goods etc. are illustrated. It should be noted that a crushed product referred to as raw coke can also be used, but raw coke is included in low temperature calcined coke. Among these, petroleum-based and coal-based mesocarbon microbeads are preferable from the viewpoints of particle size and composition uniformity, stability, and the like, and coal-based mesocarbon microbeads are more preferable from the viewpoint of carbonization yield. As the carbonaceous powder having self-sinterability, it is preferable that the carbonaceous powder has a grain size of 30 μm or less and a β-resin amount of about 3 to 50%. The compounding ratio of the carbonaceous powder having self-sinterability and the uncarbonized fiber is usually about 1 to 200 parts for the former 100 parts (representing parts by weight: the same hereinafter),
More preferably, the former is about 100 parts and the latter is about 1 to 100 parts.

The mixing means is not particularly limited as long as the carbonaceous powder having self-sinterability and the uncarbonized fiber are uniformly mixed.

The mixture thus obtained is then shaped. The molding method and conditions are the same as those used in the molding of known carbon powder having self-sintering property, and the molding is usually performed under a pressure of about 1 to 10 ton / cm ² to a predetermined size. Good. Alternatively, the molding may be performed by the CIP method or the like. Molded at room temperature or in an inert atmosphere 500
It can be performed under heating up to about ℃.

The firing may be performed under the same conditions as the known sintering of the carbonaceous powder compact having self-sintering property, and is not particularly limited, but usually in a non-oxidizing atmosphere, a rate of about 0.1 to 300 ° C./hour. The temperature may be raised from room temperature to about 1300 ° C and held for about 0.5 to 10 hours.

The obtained sintered body is then graphitized. The conditions for graphitization are also not particularly limited, and the temperature is raised from the temperature at the time of sintering in a non-oxidizing atmosphere to a temperature of about 1500 to 3000 ° C at a rate of about 0.1 to 500 ° C / hour for about 0.5 to 10 hours. Just keep it.

II. Second invention of the present application The raw material pitch used as the spinning material in the second invention of the present application is the same as that used in the first invention of the present application, and the production of pitch fibers by the spinning and the infusibilization of pitch fibers are also the same as those of the present invention. It is carried out in the same manner as one invention.

In the second invention of the present application, the obtained uncarbonized fiber is surface-treated with a material containing a caking component such as tar, pitch and organic polymer, washed with an organic solvent, and dried.

The surface treatment with the binder-containing material is 100% uncarbonized fiber.
Add about 100 to 1000 parts of the caking ingredient-containing material to each part and stir. The tar and pitch used for this surface treatment may be either petroleum-based or coal-based. When pitch is used, since heating is required during stirring, tar is more preferable as the treating material, and from the viewpoint of carbonization yield in the subsequent firing and carbonization steps, a coal-based material is preferable. More preferable. Examples of the organic polymer include phenol resin, polyvinyl chloride, polyvinyl alcohol and the like.

Next, about 100 to 1000 parts of an organic solvent is added to 100 parts of the mixture obtained in the above stirring step, stirred and washed. By this washing, the light oil containing a large amount of volatile components is removed. Examples of the organic solvent used for washing include aromatic solvents such as toluene and xylene.

The surface-treated uncarbonized fiber that has been washed is dried under conditions such as heating and / or reduced pressure in a non-oxidizing atmosphere such as N ₂ or argon. The drying treatment is not limited to these methods as long as the organic solvent used for washing is removed.

The surface-treated uncarbonized fiber that has been dried can be
Distributed processing. That is, since the dried surface-treated uncarbonized fiber may be agglomerated or aggregated, in such mixing, dispersion is carried out by any means such as a usual powder mill, atomizer, and pulverizer. .

Surface-treated uncarbonized fiber that has been subjected to dispersion treatment as necessary,
Thereafter, in the same manner as in the case of the first invention of the present application, a desired carbon-carbon composite material is obtained by mixing with a carbonaceous powder having self-sinterability, molding, and carbonizing / graphitizing.

EFFECTS OF THE INVENTION According to the method of the present invention, a high-strength, high-density carbon having a dense and uniform structure can be obtained by simple steps of molding, carbonization, and graphitization without impregnation of resin, pitch, and the like. The carbon composite material can be manufactured at low cost. That is, the high density of the high density is achieved by the simple process of simply press-molding the mixed powder, rather than the frequent method of pressure-impregnating a solid (fiber) with a liquid (liquid), which is mainly performed by the conventional method. There is a great advantage in that a carbon-carbon composite material can be manufactured.

Further, since uncarbonized fibers and carbonaceous powder are used as raw materials, shrinkage during firing occurs almost uniformly in the fiber portion and the matrix. Therefore, the gaps at the interface between the fiber and the matrix, which are found in ordinary carbon-carbon composite materials, do not occur, which is also one reason for obtaining a high-density carbon-carbon composite material. ing.

Examples Examples and comparative examples will be shown below to further clarify the characteristics of the present invention.

Example 1 Coal tar-based mesocarbon microbeads 90 having a central particle size of 7 μm per 100 parts of infusible fibers (yarn diameter 15 μm, yarn length 0.5 mm) obtained from a coal-based optically isotropic pitch by a conventional method 90
0 parts was added and mixed uniformly.

The obtained mixture was molded into a size of 50 mm in diameter and 10 mm in length with a molding pressure of 2 tons / cm ² , heated to 1000 ° C. at a rate of 150 ° C./hour, and kept at the same temperature for 1 hour. After firing, it was heated to 2800 ° C at a rate of 500 ° C / hour and held for 20 minutes.

Thus, a carbon-carbon composite material having a density of 1.89 g / cm ³ and a bending strength of 890 kg / cm ² was obtained.

Example 2 Coal tar-based mesocarbon micro beads 90 having a central particle size of 7 μm per 100 parts of infusible fiber (thread diameter 10 μm, thread length 0.5 mm) obtained from a coal-based optically anisotropic pitch by a conventional method 90
0 parts was added and mixed uniformly.

Thereafter, the physical properties of the carbon-carbon composite material obtained in the same manner as in Example 1 were a density of 1.87 g / cm ³ and a bending strength of 665 kg / cm ² .

Example 3 100 parts of infusible fibers (yarn diameter 15 μm, yarn length 6 mm) obtained from a coal-based optically isotropic pitch by a conventional method had a central particle size of 7
μm Coal Tar Mesocarbon Micro Bead 900
Parts were added and mixed uniformly.

Thereafter, the physical properties of the carbon-carbon composite material obtained in the same manner as in Example 1 were a density of 1.82 g / cm ³ and a bending strength of 791 kg / cm ² .

Example 4 100 parts of infusible fibers (fiber diameter 15 μm, yarn length 6 mm) obtained from a coal-based optically isotropic pitch by a conventional method and tar 500
Parts, stir at room temperature for 15 minutes, then filter, and further 50
0 parts of toluene was added, the mixture was stirred for 30 minutes, filtered, and dried in an N ₂ stream at 150 ° C. for 3 hours.

Next, 30 parts of the obtained tar-treated infusible fiber was added to coal tar-based mesocarbon microbeads having a central particle size of 7 μm.
After adding 70 parts, they were mixed uniformly.

The obtained mixture was molded, fired, and graphitized in the same manner as in Example 1 to obtain a desired carbon-carbon composite material.

The physical properties of the obtained carbon-carbon composite material have a density of 1.85 g / c.
It was m ³ , and the bending strength was 850 kg / cm ² .

Example 5 The density was the same as in Example 4 except that coal tar-based mesocarbon microbeads having a central particle size of 5 μm were used.
A carbon-carbon composite material with a bending strength of 1.87 g / cm ³ and a bending strength of 860 kg / cm ² was obtained.

Example 6 Oil coke (produced in Daqing, China, heat treatment temperature about 600 ° C.)
Was pulverized with a coffee mill and classified with a 235 mesh sieve to obtain a fine powder (average particle diameter 14.7 μm) under the sieve.

700 parts by weight of the obtained fine powder and 300 parts by weight of coal-based isotropic infusible pitch fiber (thread diameter 15 μm, thread length 0.5 mm) were uniformly mixed in a coffee mill.

Fill the mixed powder into a mold with a diameter of 37.5 mm, 2000 Kg / c
Molding was performed at a pressure of m ² to prepare a molded body having a diameter of 37.5 mm and a thickness of 10 mm. The density of the molded body was 1.19 g / cm ³ .

The molded body is heated up to 1000 ° C at 150 ° C / h in an N ₂ atmosphere, and 1
After holding for a time, it was cooled to obtain a fired body having a density of 1.54 g / cm ³ . Subsequently, the temperature of the fired body was increased to 2000 ° C at 500 ° C / h, and 20
After holding for minutes, it was cooled.

The obtained carbon-carbon composite material was dense in appearance, had no pores as long as it could be visually observed, and had a density of 1.80 g / cm ³ and a bending strength of 820 kg / cm ² .

Comparative Example 1 100 parts of carbonized fiber (yarn diameter 15 μm, yarn length 0.5 mm) obtained by a conventional method from coal-based optically isotropic pitch and a center particle size of 7
μm Coal Tar Mesocarbon Micro Bead 900
Parts were added and mixed uniformly.

Thereafter, a carbon-carbon composite material was obtained in the same manner as in Example 1. The physical properties were uniform, but the density was 1.71 g / c.
It was m ³ and had a bending strength of 444 kg / cm ² , which was inferior to the product of the present invention.

Comparative Example 2 100 parts of graphitized fiber (yarn diameter 15 μm, yarn length 0.5 mm) obtained from a coal-based optically isotropic pitch by a conventional method, and a coal tar-based mesocarbon microbead 90 having a central particle size of 7 μm 90
0 parts was added and mixed uniformly.

Thereafter, a carbon-carbon composite material was obtained in the same manner as in Example 1, but the physical properties thereof were extremely low, and it was impossible to measure the density and bending strength.

Comparative Example 3 100 parts of carbonized fiber (yarn diameter 10 μm, yarn length 3 mm) obtained from a coal-based optically anisotropic pitch by a conventional method had a central particle size of 7 μm.
900 parts of coal tar type mesocarbon microbeads of m were added and mixed uniformly.

Thereafter, a carbon-carbon composite material was obtained in the same manner as in Example 1. The physical properties were uniform, but the density was 1.51 g / cm ³ , and the bending strength was 95 kg / cm ² , which was higher than that of the product of the present invention. It was extremely inferior.

Comparative Example 4 Aerocarb-80 (manufactured by Ashland Petroleum, USA: softening point 25
An isotropic pitch having an oxygen content of 0.38% by weight at 8 ° C.) was crushed with a coffee mill to obtain a powder pitch having an average particle size of 27 μm.
This powder pitch is 10 ℃ from room temperature to 350 ℃ under air flow.
The mixture was heated at a temperature rising rate of / min to obtain oxidized Pichi with an oxygen content of 4.1% by weight.

To 100 parts of infusible fiber (yarn diameter 15 μm, thread length 0.5 mm) obtained from a coal-based optically isotropic pitch by a conventional method, 900 parts of the above-obtained oxidized pitch was added and mixed uniformly.

The obtained mixture was molded into a size of 50 mm in diameter and 3 mm in thickness with a molding pressure of 2 ton / cm ² . The molded body had a dense and clean appearance and had a density of 1.04 g / cm ³ .
The obtained molded body was heated to 1000 ° C. at a temperature rising rate of 150 ° C./hour in a nitrogen atmosphere, kept at the same temperature for 1 hour, and then cooled.

The obtained molded product had a sponge-like shape and was deformed, and did not retain its original shape. Therefore, it was impossible to measure the density and bending strength.

 Further, the high temperature treatment at 280 ° C was not carried out.

Comparative Example 5 To 50 parts of infusible fiber (yarn diameter 15 μm, thread length 0.5 mm) obtained from a coal-based optically isotropic pitch by a conventional method, 900 parts of the oxidized pitch obtained in Comparative Example 4 was added, Mix evenly.

The obtained mixture was molded into a size of 50 mm in diameter and 3.7 mm in thickness under a molding pressure of 2 ton / cm ² . The density of the molded body was 0.95 g / cm ³ . The obtained molded body was heated to 1000 ° C. at a temperature rising rate of 150 ° C./hour in a nitrogen atmosphere, kept at the same temperature for 1 hour, and then cooled. The obtained molded body is 500 ° C
The sample was heated to 2800 ° C. at a heating rate of / hour and held for 20 minutes.

The obtained molded product was porous and had a density of 1.23 g / cm ³ and a bending strength of 219 kg / cm ² , which were inferior to the product of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hirohisa Miura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (56) References JP 61-111963 (JP, A) JP 61-122110 (JP, A) JP 60-200867 (JP, A) JP 63-248770 (JP, A) JP 61-197466 (JP, A)

Claims (4)

[Claims] 1. Infusible pitch fibers and at least one carbonaceous powder selected from the group consisting of mesocarbon microbeads, bulk mesophase crushed products, and low temperature calcined coke crushed products are mixed, molded, and carbonized / graphite. A method for producing a carbon-carbon composite material, comprising: 2. The method for producing a carbon-carbon composite material according to claim 1, wherein the carbonaceous powder is mesocarbon microbeads. 3. The infusible pitch fiber is surface-treated with a binder-containing material, washed with an organic solvent, and dried,
Carbon-carbon characterized by mixing, molding, and carbonizing / graphitizing with at least one carbonaceous powder selected from the group of mesocarbon microbeads, bulk mesophase crushed product, low temperature calcined coke crushed product Manufacturing method of composite material. 4. The method for producing a carbon-carbon composite material according to claim 3, wherein the carbonaceous powder is mesocarbon microbeads.