JP2003192459A - Production method of carbon fiber reinforced carbon composite material coated with thermal decomposition carbon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method which achieves low-cost production of carbon fiber reinforced carbon composite material coated with thermal decomposition carbon which has excellent corrosion resistance and gas-sealing property. <P>SOLUTION: This production method of carbon fiber reinforced carbon composite material coated with thermal decomposition carbon features that carbon fiber reinforced carbon composite material is impregnated with resin or pitch which turns to optically isotropic carbon by burning, is cured or is made infusible and is burned and, thereafter, hydrocarbon gas is flown as raw material gas and hydrogen gas is flown as carrier gas thereinto and the carbon fiber reinforced carbon composition material is coated with thermal decomposition carbon at a temperature of 1200-2000°C under the reduced pressure. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a pyrolytic carbon-coated carbon fiber reinforced carbon composite material, and more particularly, to a carbon fiber reinforced carbon composite material which is optically isotropic by firing before being coated with the pyrolytic carbon. Carbon fiber reinforced carbon composite with excellent corrosion resistance by impregnating a resin or pitch that becomes a water-soluble carbon, hardening and firing, and then introducing a hydrocarbon gas as a raw material gas and a hydrogen gas as a carrier gas The present invention relates to a manufacturing method by which materials can be obtained at low cost.

[0002]

2. Description of the Related Art Pyrolytic carbon is not only excellent in heat resistance, low reactivity and chemical resistance of ordinary carbon materials, but also high in crystallinity and excellent in thermal conductivity.

Further, since pyrolytic carbon is a material having extremely low gas permeability, it exerts an excellent effect on the sealing property of various gases.

Therefore, by coating the surface of the carbon material, which is usually porous, with pyrolytic carbon, it is possible to suppress the invasion of gas into the carbon material. Therefore, pay attention to the gas sealing property of the carbon material coated with pyrolytic carbon. It is expected to be used for such purposes.

Particularly, in recent years, excellent effects have been expected on various members such as crucibles and heaters in a silicon single crystal pulling apparatus (CZ furnace).

That is, a large amount of volatile silicon monoxide (SiO gas) is generated in the CZ furnace. This SiO penetrates into the porous carbon material and silicifies the carbon material. As a result, since the carbon material deteriorates and is consumed, there is a problem that the crucible, the heater and the like using this carbon material have a very short life.

Therefore, by coating the surface of the porous carbon material with a film of pyrolytic carbon having an excellent gas sealing property, the penetration of SiO into the carbon material can be suppressed, and the progress of the reaction between the carbon material and SiO can be prevented. However, it is possible to effectively prevent deterioration and consumption due to silicidation inside the carbon material. Crucibles and heaters using such pyrolytic carbon-coated carbon material,
There is a merit that the life can be greatly extended.

However, as the base material of the pyrolytic carbon-coated carbon material, general carbon materials and graphite materials are brittle materials, and defects such as fracture are likely to occur. Therefore, even if the pyrolytic carbon is coated to improve the gas sealability and the corrosion resistance, there is a problem that the effect of extending the life is reduced due to cracking or the like.

In order to solve the above problems, carbon fiber reinforced carbon composite materials (C / C) have already been used in place of general carbon materials and graphite materials. C / C is excellent in high temperature strength and hardly causes troubles such as fracture.

As described above, C / C is an excellent carbon material, but is similar in that it is a porous material, and its pore diameter is larger than that of a general carbon material, so that it is coated with pyrolytic carbon. In that case, there is a drawback that the coating effect is not sufficient.

In order to overcome the above-mentioned drawbacks, for example, in Japanese Patent Laid-Open No. 10-59795, a method of significantly slowing the deposition rate of pyrolytic carbon and filling the pores of C / C with pyrolytic carbon is disclosed. Is listed. But with this method,
Since the deposition rate of pyrolytic carbon is remarkably slow, the C / C finally obtained is very expensive. Further, since pyrolytic carbon is classified into carbon that easily reacts with SiO, the effect of corrosion resistance is not sufficient in applications such as CZ furnace members. As described above, according to the conventional technique, it is difficult to produce C / C at a low cost by sufficiently enhancing the effect of the pyrolytic carbon coating.

[0012]

In view of the above situation, the present inventor has
Provided is a method for inexpensively producing a pyrolytic carbon-coated carbon fiber reinforced carbon composite material having excellent corrosion resistance and gas sealability.

[0013]

In order to solve the above problems, the inventor of the present invention has made extensive studies, and as a result, the following (1) to
The present invention was completed focusing on (3). (1) Optically isotropic carbon obtained by firing a thermosetting resin or the like is less likely to react with SiO than optically anisotropic carbon. (2) The filling of the pores of the carbon fiber reinforced carbon composite material with a thermosetting resin or the like is relatively inexpensive and easy. (3) When the surface of the carbon fiber reinforced carbon composite material whose pores are filled with a thermosetting resin or the like is coated with pyrolytic carbon, a gas sheet
It has excellent resistance and corrosion resistance.

That is, according to the present invention, a carbon fiber-reinforced carbon composite material is impregnated with a resin or pitch which becomes carbon which is optically isotropic by firing, and after curing or infusibilizing and firing,
It is a method for producing a pyrolytic carbon-coated carbon fiber reinforced carbon composite material, in which a hydrocarbon gas as a raw material gas and a hydrogen gas as a carrier gas are introduced at 1200 to 2000 ° C. under reduced pressure to coat pyrolytic carbon. The present invention will be described in detail below.

First, the carbon fiber reinforced carbon composite material (C / C) as the base material is irrespective of the type of carbon fiber as a raw material, the type of resin binding the carbon fiber, the manufacturing method, the densifying material, etc. Almost any C / C can be used.

C / C is generally porous and has a large number of pores and has a large pore diameter. Therefore, the present invention is characterized by impregnating the impregnating material and filling the pores before the C / C is coated with the pyrolytic carbon.

As the impregnating material, a resin or pitch which becomes an optically isotropic carbon by firing is used. An isotropic material exhibits an effect of excellent corrosion resistance, such as being less likely to react with SiO, than an optically anisotropic material. As the resin, a thermosetting resin such as a phenol resin or a furan resin is preferable because it can form an optically isotropic carbon by firing. Any pitch can be used as long as it is solidified by infusibilization to produce optically isotropic carbon.

The impregnating amount of the impregnating material is such that the weight increase amount after C / C firing is 3% or more as compared with that before impregnation. If the amount of weight increase is less than 3%, the amount of resin or pitch filled in the C / C pores will be insufficient, and the corrosion resistance will not improve.

After the impregnation, it is hardened or made infusible and then baked. When impregnated with a resin, it is cured by heating at 100 to 250 ° C. When the pitch is an impregnated material, it is usually infusibilized at 250 to 350 ° C. in air so that the pitch does not soften and melt in the subsequent firing step. After curing and infusibilization, firing is performed, but the firing temperature is not particularly limited and is usually 80
A temperature of 0 ° C or higher is sufficient.

As described above, the present invention is characterized in that the C / C is impregnated with an impregnating material, cured or infusibilized, and fired before coating C / C with C / C after firing. Is preferably processed into a product shape and purified. The purification treatment is usually a heat treatment at 1500 ° C. or higher in a halogen gas atmosphere.

The carbon material processed and purified as described above is coated with pyrolytic carbon. For coating, a hydrocarbon gas selected from methane, ethane, propane, butane, etc. is used as a source gas, and hydrogen gas is used as a carrier gas.

The coating conditions are 1200 ° C. under reduced pressure.
~ 2000 ° C, more preferably 1300 ° C-1700
It shall be heat treated at ° C. Heat treatment temperature is 1200 ℃
If it is less than 200 ° C., the film of pyrolytic carbon becomes porous and the gas sealability becomes poor.
Neither is preferable.

By the method as described above, a pyrolytic carbon-coated carbon fiber reinforced carbon composite material excellent in corrosion resistance and gas sealability can be manufactured at low cost.

[0024]

According to the present invention, a pyrolytic carbon-coated carbon fiber reinforced carbon composite material excellent in gas sealability and corrosion resistance can be manufactured at low cost. In particular, a pyrolytic carbon-coated carbon fiber reinforced carbon composite material that exhibits excellent effects in a crucible of a silicon single crystal pulling apparatus can be provided at low cost and is industrially useful.

[0025]

[Examples and Comparative Examples]

Example 1 A carbon fiber reinforced carbon composite material (product name: CCM-190C manufactured by Nippon Carbon Co., Ltd.) having a diameter of 800 mm and a height of 500 mm was impregnated with a commercially available phenol resin diluted with methanol. After hardening at 200 ° C., it was baked at 1000 ° C. in a nitrogen atmosphere. The amount of increase in weight after firing was 4.5% compared to that before impregnation. After this was finally processed into a crucible shape, it was heat-treated at 2000 ° C. in a hydrogen chloride atmosphere to obtain a high-purity carbon fiber-reinforced carbon composite crucible.
Propane 2 L / min and hydrogen gas 30 L / mi were added to the crucible at 1500 ° C. under a reduced pressure of 100 torr.
n was obtained and a pyrolysis carbon-coated carbon fiber-reinforced carbon composite crucible was obtained.
A sample with a size of 0 mm is cut out and the temperature is set to 1500.
The reaction was performed with silicon monoxide at 30 ° C. for 10 hours at 30 torr in an argon gas stream, and the cross section was observed with a polarizing microscope. The thickness of the generated silicidation layer was 20 μm.

[0026]

Comparative Example 1 A crucible made of a carbon fiber reinforced carbon composite material coated with pyrolytic carbon was obtained in the same manner as in Example 1 except that the phenol resin was not impregnated. A sample of the same size as in Example 1 was cut out from this crucible, and this was reacted with silicon monoxide under the same conditions as in Example 1 to measure the thickness of the silicified layer formed. As a result, the thickness of the silicified layer was 30 μm on average, but a part of the silicified layer of 100 μm was recognized.

[0027]

Comparative Example 2 A crucible made of a carbon fiber reinforced carbon composite material coated with pyrolytic carbon was obtained in the same manner as in Example 1 except that the deposition temperature of pyrolytic carbon was set to 1100 ° C. A sample having the same size as in Example 1 was cut out from this crucible, and the thickness of the silicified layer produced by reacting with silicon monoxide under the same conditions as in Example 1 was measured. As a result, the thickness of the silicified layer was 90 μm.

[0028]

[Comparative Example 3] The same procedure as in Example 1 was repeated except that the deposition temperature of pyrolytic carbon in Example 1 was set to 2200 ° C.
A carbon fiber reinforced carbon composite material coated with pyrolytic carbon was obtained. A sample of the same size as in Example 1 was cut out from this crucible, and the thickness of the silicified layer formed by reacting with silicon monoxide under the same conditions as in Example 1 was measured. As a result, the thickness of the silicified layer was 50 μm. .

Claims (3)

[Claims] 1. A carbon fiber-reinforced carbon composite material is impregnated with a resin or pitch which becomes an optically isotropic carbon by firing, and is cured or infusibilized and fired, and then under reduced pressure.
A method for producing a pyrolytic carbon-coated carbon fiber reinforced carbon composite material, which comprises flowing a hydrocarbon gas as a raw material gas and a hydrogen gas as a carrier gas at 00 to 2000 ° C. to coat the pyrolytic carbon. 2. The heat according to claim 1, wherein an impregnated amount of the resin or pitch is set such that a weight increase amount of the carbon fiber reinforced carbon composite material after firing is 3% or more as compared with that before impregnation. A method for producing a decomposed carbon-coated carbon fiber reinforced carbon composite material. 3. The carbon fiber reinforced carbon composite material according to claim 1 or 2, after being fired, processed into a product shape, and heat-treated at a temperature of 1500 ° C. or higher in a halogen gas atmosphere before coating with pyrolytic carbon. A method for producing a pyrolytic carbon-coated carbon fiber reinforced carbon composite material, which comprises purifying.