JPH05186286A - Oxidation resistant coating method of carbon material - Google Patents

Abstract

PURPOSE:To readily convert even a material having large graphitization degree and form an oxidation resistant film by packing a gas reaction component forming substance around a carbon material and further packing a liquid reaction component forming substance in the circumference of the gas reaction component forming substance and heating these substances at a prescribed temperature. CONSTITUTION:A gas reaction component forming substance (SiO, a mixture of C with SiO2, etc.) 2 having 0.1-840mum particle diameter is packed around a carbon material 1. A liquid reaction component forming substance (Si or ceramic powder containing Si) 3 is packed further in the circumference of the gas reaction component forming substance. Then these substances are heated to 1800-2000 deg.C to generate SiO vapor from the substance 2 and thereby the interior and surface part of the carbon material 1 is formed into a SiC conversion layer 4. Then, temperature of is cooled to 1600-1800 deg.C and a new SiC layer 5 formed from the liquefied substance 3 is formed on the carbon material 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxidation resistant coating method for carbon materials, especially carbon composite materials (C / C composite materials). And a method of coating a carbon material for the purpose of supplying a material capable of withstanding repeated use in a high temperature oxidizing atmosphere, such as a structural material such as a spacecraft, a turbine blade and a graphite member for a nuclear reactor. ..

[0002]

BACKGROUND OF THE INVENTION Carbon materials are good conductors of electricity and heat, and at the same time have many unique physical and chemical properties such as unrivaled heat resistance, corrosion resistance and lubricity. It has been used in various fields such as moderators, crucibles for refining high-purity semiconductor metals, and electrodes for electrical discharge machining. Further, recently, as the strength of carbon fiber has been increased and the production technology of C / C composite material has been improved, its use in the aerospace field has expanded. Here, the C / C composite material means that carbon fiber / phenol resin, carbon fiber / tar pitch, etc. are carbonized or graphitized by primary firing, and further impregnation / firing of resin or tar pitch is repeated, or by a gas phase reaction method. It is obtained by densifying by pyrolytic carbon deposition. By the way, in the aerospace field, particularly when used as a structural material for a spacecraft (so-called space plane), an oxidation resistant coating is required as an indispensable technique. Therefore, various methods have been studied in various countries and various research institutions.

In Japanese Patent Laid-Open No. 60-155586, a carbon base material is embedded in SiC powder, which is used as an inert gas or a reducing gas as a carrier gas in a gas stream containing halogen at 1500 to 2200 ° C. A method of forming a coating film of SiC on the surface of a carbon substrate by heat-treating in the temperature range of 2 is disclosed.

Japanese Patent Laid-Open No. 02-69382 discloses C /
After depositing metallic silicon powder on the outer surface of the C composite material and performing heat treatment in an inert gas atmosphere to generate silicon carbide on the outer surface in advance, silicon carbide is deposited by a vapor phase chemical reaction deposition method (CVD method). Disclosed is a method for producing a C / C composite material, which comprises forming a coating film made of OH on the outer surface, and then impregnating the coating film with boron oxide or a mixture of boron oxide and silicon oxide. Has been done.

Japanese Unexamined Patent Publication (Kokai) No. 61-27248 discloses a pack-diffusion SiC having a carbon / carbon composite material substrate and a surface integral with the substrate and having a thickness of substantially 12.7 to 762 μm. Coating, substantially 76.2-7
A carbon-carbon composite material having a thickness of 62 μm and comprising Si ₃ N ₄ deposited by CVD on the outer surface of the SiC coating is disclosed.

[0006]

Problems to be Solved by the Invention JP-A-60-1555
The method for coating a carbon-based material with SiC described in Japanese Patent Publication No. 86 is achieved by reacting Si gas generated by decomposition of SiC with the carbon-based material. However, in this method, it is difficult to control the reaction depth because the reaction component in the SiC formation is only the gas species. Furthermore, this method is C / C
C / C using composite material, especially resin as matrix
When applied to a composite material, the Si component, which is a reaction component, preferentially attacks the matrix portion having a low degree of graphitization, so that the adhesion between the carbon fiber cloths is reduced and finally the cloth is peeled off. Further, since the oxidation resistance is to be improved only by this method, the reaction depth must be deepened, resulting in a decrease in the strength of the material. For the above reasons, this method is not preferable when coating the C / C composite material used as the structural material.

Japanese Unexamined Patent Publication No. 02-69382 discloses C /
As a thermal stress relaxation layer for relaxing the thermal stress caused by the difference in the coefficient of thermal expansion between the C composite material and the silicon carbide film formed by the CVD method, the C / C composite material is preliminarily prepared by the reaction of metallic silicon and carbon on the outer surface thereof. It is stated that silicon carbide is produced. However, this publication makes no mention of the reactivity between Si and carbon. That is, the reactivity of carbon with metallic silicon varies depending on the degree of graphitization of carbon, and the reactivity of Si and carbon is important in the production of oxidation resistant C / C. During the heat treatment in the manufacturing process of the C / C composite material, due to a phenomenon called stress graphitization, even non-graphitizable carbon grows large graphite crystals in the fiber axis and 90 ° direction. When a pitch in which the crystallites of graphite become large even when heat-treated as it is is used as a matrix, the layered structure is significantly developed and the reactivity with other elements is significantly reduced. On the other hand, from the viewpoint of economical efficiency and high strength, it is very common to use pitch as a matrix. That is,
In the case of a C / C composite material in which a graphitizable raw material such as pitch or pyrolytic carbon is used as a matrix, even if metal Si is simply attached to cause a chemical reaction with carbon, the C / C composite material is activated. Since there are few sites, it is very difficult to form a desired thermal stress relaxation layer. That is,
The method described in JP-A-02-69382 is not a method applicable to all C / C composite materials, but C / C
The range of applications for composite materials is very limited.

Japanese Unexamined Patent Publication No. 61-27248 discloses a pack-diffused Si having a thickness of 12.7 μm to 762 μm.
The C layer is characterized by being used as a thermal stress relaxation layer, but the state of the conversion layer is not recorded at all. That is, the pack diffusion reaction layer in the C / C composite material is entirely Si.
If it is converted to C, the strength of the C / C composite material is greatly lowered, and the exfoliation of the carbon fiber cloth is easily promoted. Therefore, only those having extremely low resistance to thermal shock are produced. I can't. Furthermore, C /
Although the surface layer of the C composite material has been converted to SiC, its characteristics basically depend on the orientation of the fibers, so it is completely necessary to improve the adhesion to the upper CVD / SiC layer. Is useless.

As described above, a carbon material whose main raw material is an easily graphitizable raw material such as tar pitch or pyrolytic carbon generally has a high degree of graphitization and a small number of active sites, and therefore has poor reactivity with other elements. There was a flaw. Therefore, regarding the C / C composite material, which is expected to be used as an aerospace material (structural material for spacecraft, etc.) in recent years, the conventional method using tar pitch is changed to the method using non-graphitizable phenol or furan resin. There was also a serious problem in manufacturing, such as being forced to change to. In this case, there is a drawback that the strength of the obtained C / C composite material is lowered.

An object of the present invention is to solve the above problems and to provide an oxidation resistant coating method for a carbon material capable of easily reacting a material having a high degree of graphitization to form an oxidation resistant film. There is.

[0011]

In order to solve the above problems, the inventors of the present invention have made extensive studies and arrived at the present invention. The present invention simultaneously fills a reaction system with a gas reaction component and a liquid reaction component that can react with a carbon material and can form a film that effectively acts as an oxidation resistant film, and the gas reaction component is first charged with carbon in the heating step. It is characterized in that the carbon material is subjected to oxidation-resistant coating by using a reaction system which reacts with the material and at the same time or after that, the liquid reaction component can react with the carbon material.

That is, according to the first aspect of the present invention in order to achieve the above object, when the carbon material is subjected to the oxidation resistant coating, it is possible to react with the carbon material around the carbon material as an oxidation resistant film. A gas reaction component forming substance capable of forming an effective film is filled, and a liquid reaction component forming substance capable of forming a film capable of reacting with a carbon material and effectively acting as an oxidation resistant film is filled around the substance. There is provided an oxidation resistant coating method for a carbon material, which is characterized by carrying out the reaction.

Here, the gas reaction component forming substance is S
iO, a mixture of C and SiO ₂ or SiO, C and Si
It is preferably a material selected from a mixture with O ₂ .

The particle size of the gas reaction component forming substance is preferably in the range of 0.1 to 840 μm.

The liquid reaction component forming substance is preferably Si.

The oxidation resistant coating reaction of the carbon material is preferably carried out in a vacuum or an inert gas atmosphere.

In the oxidation resistant coating reaction of the carbon material, the gas reaction component forming substance is heated to a temperature at which SiO vapor is generated and then heated to a temperature at which the liquid reaction component forming substance is melted and reacts with the carbon material. It is preferable to carry out.

The heating at the temperature for generating the SiO vapor is preferably in the range of 1800 to 2000 ° C.

The heating at a temperature at which the liquid reaction component forming substance melts and reacts with the carbon material is preferably in the range of 1600 to 1800 ° C.

The heating time at the temperature for generating the SiO vapor is preferably 5 to 120 minutes.

The heating time at the temperature at which the liquid reaction component forming substance melts and reacts with the carbon material is preferably 30 to 600 minutes.

The gas reaction component forming substance is preferably filled so as to be in close contact with the periphery of the carbon material and have a thickness of 1 to 5 mm.

According to the second aspect of the present invention, the oxidation resistant coating of the carbon material is selected from SiO, a mixture of C and SiO ₂ and a mixture of SiO, C and SiO ₂ around the carbon material. The material is filled with
An oxidation-resistant coating of a carbon material, characterized in that the surface of the carbon material is converted into SiC by filling ceramic powder containing i and heat treatment, and then a dense SiC film is formed by a chemical vapor reaction method. A method is provided.

Further, according to the third aspect of the present invention, when the carbon composite material having the carbon fibers and the matrix is subjected to the oxidation resistant coating, it can react with the carbon material filled around the carbon composite material and is resistant to the acid. The carbon fiber and the matrix are converted to SiC from the deepest part of the carbon material to the surface layer by reaction with a gas reactive component forming substance capable of forming a film that effectively acts as a chemical film, and a carbon material filled around the carbon fiber and the matrix. Provided is an oxidation resistant coating method for a carbon material, which comprises forming a new SiC coating on the SiC by a liquid reaction component forming substance capable of forming a coating capable of reacting and effectively acting as an oxidation resistant coating. To be done.

Si newly formed on the SiC
The C layer thickness is preferably 5 to 200 μm.

The present invention will be described in more detail below.

The carbon materials that can be used in the present invention are general carbon materials, special carbon materials and C / C composite materials. Among them, particularly suitable for coating C / C composite materials using tar pitch as a matrix. Is the way.

In the present invention, in the oxidation resistant coating of a carbon material, a gas reactive component-forming substance capable of reacting with the carbon material and forming a film which effectively acts as an oxidation resistant film is filled around the carbon material, It is necessary to fill the periphery thereof with a liquid reaction component forming substance capable of reacting with the carbon material and effectively acting as an oxidation resistant film. That is, when the liquid reaction component is present in close contact with the carbon material, the reaction at a high temperature is considered to occur while the liquid reaction component permeates into the inside from the porous part of the carbon material, but the degree of graphitization is particularly large. This is because, when the pitch-based C / C composite material is coated, the liquid reaction component hardly diffuses internally and stays on the surface portion to form a reaction conversion site of only about several μm. On the contrary, when the gas reaction component is arranged around the carbon material as in the present invention, the initial reaction between the carbon material and the reaction component proceeds as a reaction between the gas phase and the solid phase. in this case,
Since the diffusion of the gas into the solid is not influenced by the surface tension, it can freely penetrate into the inside of the carbon material, and as a result, a reaction conversion layer having a deep reaction depth can be formed.
Moreover, since the reaction between the gas component and the carbon material is more likely to occur than the reaction between the liquid component and the carbon material,
The reaction does not stop on the surface of the carbon material, and the reaction does not proceed preferentially on either the matrix or the carbon fiber.

The gas reaction component forming substance capable of reacting with the carbon material and capable of forming a film which effectively acts as an oxidation resistant film is such that the resulting ceramic film is heat and oxidation resistant and in the subsequent step (CVD). Since the film to be used is silicon carbide that is inexpensive and can be stably formed as a heat-resistant material, Si that reacts with the carbon material to form silicon carbide
O, a mixture of C and SiO ₂ , and SiO, C and Si
It is preferably a material selected from a mixture with O ₂ . Of these, a mixture of C and SiO ₂ is particularly preferable in view of its low cost and easy handling.
When a mixture of C and SiO ₂ is used, the molar ratio is preferably in the range of 1: 3 to 3: 1, and more preferably equimolar. That is, in the case of an equimolar mixture, C and SiO ₂ disappear when the surface of the carbon material is converted into SiC.
Furthermore, the particle size of SiO, C, and SiO ₂ is 0.1 to 84.
It is preferably in the range of 0 μm. That is, when the particle size is larger than 840 μm, the contact area between particles is small, the reaction efficiency is lowered, and there is a high possibility that the particles remain after the completion of the reaction, which is not preferable. When the particle diameter is smaller than 0.1 μm, the carbon material is apt to be clogged with C, particularly when a mixture of C and SiO ₂ is used, and as a result, the effect of vapor phase diffusion is reduced, which is not preferable.

The reaction between the gas reaction component forming substance and the carbon material is preferably carried out by heating to a temperature at which SiO vapor is generated,
The range of 1800 to 2000 ° C is preferable. Ie 1
At temperatures lower than 800 ° C, carbon materials and gaseous reaction components such as SiO (in the case of C and SiO ₂ , SiO is generated and reacts)
This is because there is almost no reaction with
This is because if the temperature exceeds 0 ° C., the reaction proceeds too much and the carbon material is destroyed (SiO has a melting point of 1700 ° C.). Also,
The reaction time between the carbon material and the gas reaction component is preferably in the range of 5 to 120 minutes at the above reaction temperature. That is, if the time is less than 5 minutes, the progress of the reaction cannot be expected, and if it exceeds 120 minutes, it is not preferable because the carbon material is destroyed or the strength is remarkably reduced due to the excessive reaction.

The thickness of the gas reaction component-forming substance that is closely packed in the periphery of the carbon material is preferably in the range of 1 to 5 mm. That is, the feature of the present invention is that the gas reaction component-forming substance disappears from the reaction system or the existing amount thereof becomes almost zero after the carbon material and the gas reaction component react with each other under the reaction conditions. Because it is. As a result, after the reaction of the gas reaction component, the liquid reaction component forming substance newly surrounds the periphery of the carbon material, and the liquid reaction component forming substance and the carbon material react with each other to form the CVD.
When the treatment is performed, the adhesion between the CVD layer and the C / C composite material becomes good. That is, if the thickness of the gas reaction component forming substance is more than 5 mm, the gas reaction component forming substance remains after the reaction for a predetermined time and interferes with the contact between the liquid reaction component forming substance and the carbon material, which is not preferable. On the contrary, when the thickness of the gas reaction component forming substance is less than 1 mm, the inside and the surface layer of the carbon material cannot be sufficiently converted into SiC, which is not preferable.

As the liquid reaction component forming substance capable of forming a film capable of reacting with the carbon material and effectively acting as an oxidation resistant film, Si or a ceramic powder containing Si is preferable. More preferably, the ceramic powder is mainly formed of SiC. That is, in this reaction, not only the surface layer of the carbon material needs to be converted into SiC, but also a new SiC layer needs to be formed on the surface of the carbon material.
This is because layers cannot be formed. Si on the surface of carbon material
The purpose of forming the C layer is to form a CVD film further above.
This is to improve the adhesion between the SiC layer and the carbon material. That is, in the case of a carbon composite material, even if the carbon fiber cloth is converted into SiC by a conventional method, it still has anisotropy, and it is difficult to become a nucleus for forming a CVD / SiC film. However, by forming a new SiC layer on the upper portion of the carbon material as in the present invention, a reaction nucleus is formed, and CV having excellent adhesion is formed on the upper portion.
A D / SiC layer can be formed. In this case, the SiC film formed on the upper portion is preferably porous as described in JP-A-02-74669.

The reaction temperature between the liquid reaction component forming substance and the carbon material is preferably in the range of 1600 to 1800 ° C. That is, at a temperature lower than 1600 ° C., the reaction between the liquid reaction component and the carbon material does not proceed sufficiently,
On the contrary, if the temperature exceeds 1800 ° C., the new SiC layer formed on the upper portion of the carbon material becomes too dense and is not useful for releasing thermal stress, which is not preferable.

The reaction time between the liquid reaction component and the carbon material is
It is preferably in the range of 30 to 600 minutes under the above reaction conditions. That is, when the time is shorter than 30 minutes, the progress of the reaction is insufficient, and when the time is longer than 600 minutes, the coating formed on the upper portion becomes too dense or too thick, which is not preferable.

Further, it is preferable that all the reaction between the carbon material and the gas or liquid reaction component forming substance is carried out in a vacuum or an inert gas atmosphere. That is, when another atmosphere gas is used, the SiC forming reaction of the carbon material interferes.

After converting the surface of the carbon material into SiC, a dense SiC film can be formed by a chemical vapor reaction (CVD) method. The coating of SiC by CVD is one of the most commonly used methods, for example silicon tetrachloride (or zirconium carbide, hafnium carbide),
Mixed gas of methane, hydrogen and argon (volume ratio 1: 1:
5: 1) under reduced pressure of 10 to 400 mmHg and 1000
It can be obtained by reacting at a temperature of ~ 1500 ° C for about 20 to 300 minutes. However, the reaction conditions of the CVD method are very different depending on the crystal structure of the SiC to be precipitated and the type of raw material gas used, and are not necessarily limited to the above reaction conditions.

According to the above method, the oxidation resistant coating can be easily applied not only to the ordinary carbon material but also to the C / C composite material having pitch carbon as a matrix. In this case S
The thickness of the SiC film newly formed on the iC conversion layer is preferably 5 to 200 μm. This thickness is 5
If it is less than μm, it is difficult to become a nucleus for forming the CVD / SiC layer, and if it exceeds 200 μm, breakage easily occurs in the film, which is not preferable.

FIG. 1 is a sectional view of a carbon material obtained by applying an oxidation resistant coating according to the present invention. 1 is a carbon material, 4 is SiC produced mainly by a reaction with a gas reaction component forming substance
The conversion layer, 5 is a SiC forming layer (sintered layer) generated by the reaction with the liquid reaction component forming substance, and 3 is the liquid reaction component forming substance.

2 to 4 are cross-sectional views of a carbon material showing the state change with time in the reaction process of the present invention. 2 shows a state before the reaction, FIG. 3 shows a state where the gas reaction component forming substance is reacting, and FIG. 4 shows a state where the liquid reaction component forming substance is reacting. 2 is a gas reaction component forming substance. When the reaction of FIG. 4 is completed, the target product in the state shown in FIG. 1 is obtained.

[0040]

EXAMPLES The present invention will be specifically described below based on examples. (Example 1) A C / C composite material used as a base material was produced by the following method. Two-dimensional carbon fiber woven cloth (use thread:
PAN-based high elastic carbon fiber, 1K8HS) 300 × 30
It was cut to 0 mm and impregnated with phenol resin (Dainippon Ink and Chemicals, Inc.) to obtain a prepreg. At this time,
The resin areal weight was adjusted to 85 g / m ² . Twelve sheets of this prepreg were laminated and set in a vacuum bag. After setting in the autoclave, while vacuuming the inside of the vacuum bag, it was heated to 150 ° C. and molded. At this time, the pressure inside the autoclave was set to 5 kg / cm ² . The carbon composite material precursor (FRP) thus obtained was post-cured to 20
After 5 hours at 0 ℃, under argon gas flow, 5 ℃ / min
The temperature was increased to 1000 ° C. to obtain a C / C composite material having a thickness of 1.5 mm. This C / C composite material
Tar pitch (impregnated pitch manufactured by Kawasaki Steel Co., Ltd., trade name p
K-QL) was impregnated and fired 5 times to increase the density and strength.

The C / C composite material obtained by the above method was cut into 50 × 50 mm, and SiO particles (made by Osaka Titanium Manufacturing Co., Ltd., particle size 4) were cut around the C / C composite material.
4 to 105 μm) was used and arranged so that the layer thickness was 3 mm. Further, the mixing ratio of Si and SiC is set to 7: 3.
The mixed powder (weight ratio) was placed around SiO, and these were put in a graphite container and set in an electric furnace. After evacuating the electric furnace to 10 ⁻³ torr, Ar was introduced and the pressure was increased to 2 kg / cm ² . After that, at a heating rate of 10 ° C / min, 1900 ° C
The inside of the C / C composite material and the surface layer part were converted into SiC by heating up to and holding it for 30 minutes. Further 17
After cooling to 00 ° C., a new SiC layer was formed on the surface layer part of the C / C composite material and outside by liquid Si. The holding time of the mushroom was 120 minutes.

After the thermal stress relaxation layer was formed on the C / C composite material by the method described above, a dense SiC layer was formed further on the CVD method. The reaction conditions in the CVD coating are methyltrichlorosilane (CH ₃ SiCl) as a reaction gas.
Hydrogen gas containing about 5 wt% of ₃ ) was fed at 12 l / min, and the reaction temperature was 1000 ° C. and the reaction pressure was 15 torr.
It was made to react for a time.

Oxidation resistant coating C obtained by the above method
The / C composite material was put in a horizontal electric furnace, and an oxidation test was carried out by holding it at 1500 ° C for 60 minutes. The results are shown in Table 1.

Example 2 A C / C composite material similar to that used in Example 1 was cut into a size of 50 × 50 mm,
The particle size of C and SiO ₂ was adjusted to be in the range of 105 to 177 μm, and the equimolar mixture was applied to the C / C composite material to form a layer thickness 1
It was arranged to be mm. Further, the mixing ratio of Si and SiC was set to 7: 3 (weight ratio), the mixture was placed around the mixture of C and SiO ₂ particles, and these were put in a graphite container and set in an electric furnace. After exhausting the electric furnace to 10 ^-3 torr, Ar
Was introduced and the pressure was increased to 2 kg / cm ² . After that, the inside and the surface layer of the C / C composite material were converted to SiC by heating to 1950 ° C. at a heating rate of 10 ° C./min and holding for 45 minutes. After further cooling to 1700 ° C., a new SiC is added to the surface layer of the C / C composite material and the outside by liquid Si.
Layers were formed. The holding time at this time was 120 minutes.

After the thermal stress relaxation layer was formed on the C / C composite material by the above method, the CVD was performed under the same conditions as in Example 1.
A dense SiC layer was formed on the upper part by the method.

Oxidation resistant coating C obtained by the above method
The / C composite material was put in a horizontal electric furnace, and an oxidation test was carried out by holding it at 1500 ° C for 60 minutes. The results are shown in Table 1.

Comparative Example 1 The same C / C composite material as that used in Example 1 was cut into a size of 50 × 50 mm, and C
And an equimolar mixture of SiO ₂ particles were placed in a graphite container and set in an electric furnace. At this time, the particle diameters of C and SiO ₂ particles were 105 to 177 μm as in Example 2, and were arranged around the C / C composite material so as to have a thickness of 10 mm. Then 195 at a heating rate of 10 ° C / min
The inside and the surface layer of the C / C composite material were converted to SiC by heating to 0 ° C. and holding for 45 minutes. Further, a dense SiC layer was formed on the upper portion by the CVD method under the same reaction conditions as in Example 1.

Oxidation resistant coating C obtained by the above method
The / C composite material was put in a horizontal electric furnace, and an oxidation test was carried out by holding it at 1500 ° C for 60 minutes. The results are shown in Table 1.

Comparative Example 2 The same C / C composite material as that used in Example 1 was cut into a size of 50 × 50 mm,
It was put into a graphite container together with a mixture of Si and SiC (weight ratio 3: 7) and set in an electric furnace. At this time, Si and SiC were arranged around the C / C composite material so as to have a thickness of 15 mm. After that, at a heating rate of 10 ° C / min, 17
C / C by heating to 00 ℃ and holding for 120 minutes
The interior and surface of the composite material was converted to SiC. Further, under the same conditions as in Example 1, a dense SiC layer was formed on the conversion layer by the CVD method.

Oxidation resistant coating C obtained by the above method
The / C composite material was placed in a horizontal electric furnace and an oxidation test was carried out by holding it at 1500 ° C for 60 minutes. The results are shown in Table 1.

(Comparative Example 3) The oxidation-resistant coated C / C composite material was placed in a horizontal electric furnace at 1500 ° C under the same conditions as in Comparative Example 2 except that the holding time at 1700 ° C was 360 minutes. Then, an oxidation test was carried out for 60 minutes. The results are shown in Table 1.

As is clear from Table 1, Examples 1 and 2
Showed a small weight loss after the oxidation test and showed good oxidation resistance.

[0053]

[0054]

EFFECTS OF THE INVENTION Since the present invention is configured as described above, gas-phase / solid-phase reactions are combined with liquid-phase / solid-phase reactions, among which gas-phase / solid-phase reactions are preferentially performed. By doing so, even a material having a high degree of graphitization can be easily subjected to reaction conversion to easily obtain an oxidation resistant film. As a result, inexpensive tar pitch can be used also in the production of the C / C composite material, and a high-strength material can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a carbon material obtained by the present invention.

FIG. 2 is a cross-sectional view of a carbon material showing a state before a reaction according to the present invention.

FIG. 3 is a cross-sectional view of a carbon material showing a state in which a gas reaction component forming substance is reacting according to the present invention.

FIG. 4 is a cross-sectional view of a carbon material showing a state in which a liquid reaction component forming substance is reacting according to the present invention.

[Explanation of symbols]

 1 carbon material 2 gas reaction component forming substance 3 liquid reaction component forming substance 4 SiC conversion layer 5 SiC formation layer (sintered layer)

Claims (14)

[Claims] 1. When a carbon material is coated with an oxidation resistant material, a gas reactive component forming substance capable of reacting with the carbon material and forming a film that effectively acts as an oxidation resistant film is filled around the carbon material, An oxidation-resistant coating method for a carbon material, characterized in that the reaction is performed by filling a liquid reaction component forming substance which can react with the carbon material and can form a film effectively acting as an oxidation-resistant film around the periphery. 2. The gas reaction component forming substance is SiO or C.
The oxidation resistant coating method for a carbon material according to claim 1, which is a material selected from a mixture of SiO ₂ and SiO ₂ and a mixture of SiO, C and SiO ₂ . 3. The particle size of the gas reaction component forming substance is 0.
The oxidation resistant coating method for a carbon material according to claim 1 or 2, which has a range of 1 to 840 µm. 4. The oxidation resistant coating method for a carbon material according to claim 1, wherein the liquid reaction component forming substance is Si or a ceramic powder containing Si. 5. The oxidation resistant coating method for a carbon material according to claim 1, wherein the oxidation resistant coating reaction of the carbon material is performed in a vacuum or in an inert gas atmosphere. 6. The oxidation resistant coating reaction of the carbon material is carried out at a temperature at which the liquid reaction component forming substance melts and reacts with the carbon material after the gas reaction component forming substance is heated to a temperature at which SiO vapor is generated. The oxidation resistant coating method for a carbon material according to claim 1, which is carried out by heating. 7. Heating the temperature for generating the SiO vapor comprises:
The oxidation resistant coating method for a carbon material according to claim 6, which is in the range of 1800 to 2000 ° C. 8. The oxidation resistant coating method for a carbon material according to claim 6, wherein the heating at a temperature at which the liquid reaction component forming substance melts and reacts with the carbon material is in the range of 1600 to 1800 ° C. 9. The oxidation resistant coating method for a carbon material according to claim 6, wherein a heating time at a temperature for generating the SiO vapor is 5 to 120 minutes. 10. The method for coating an oxidation resistant coating of a carbon material according to claim 6, wherein a heating time at a temperature at which the liquid reaction component forming substance melts and reacts with the carbon material is 30 to 600 minutes. 11. The oxidation resistant carbon material according to claim 1, wherein the gas reaction component forming substance is filled in close contact with the periphery of the carbon material so as to have a thickness of 1 to 5 mm. Coating method. 12. An oxidation resistant coating of a carbon material, wherein SiO, a mixture of C and SiO ₂ and S are provided around the carbon material.
A material selected from a mixture of iO, C, and SiO ₂ is filled, and the outer periphery thereof is filled with a ceramic powder containing Si, and the surface of the carbon material is converted into SiC by heat treatment, and then a chemical vapor is added. Precise S by phase reaction method
An oxidation resistant coating method for a carbon material, which comprises forming an iC film. 13. When a carbon composite material having carbon fibers and a matrix is oxidation-resistant coated, a coating capable of reacting with the carbon material filled around the carbon composite material and effectively acting as an oxidation-resistant coating is formed. Converting the carbon fibers and matrix into SiC from the deepest part of the carbon material to the surface layer by reaction with a gaseous reaction component forming substance,
Further, a new S component is added to the upper portion of the SiC by a liquid reaction component forming substance capable of reacting with the carbon material filled around it and forming a film that effectively acts as an oxidation resistant film.
An oxidation resistant coating method for a carbon material, which comprises forming an iC film. 14. S newly formed on the SiC.
The oxidation resistant coating method for a carbon material according to claim 13, wherein the iC coating has a thickness of 5 to 200 μm.