JP2002087895A - Oxidation resistant carbonaceous material and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxidation resistant carbonaceous material having excellent oxidation resistance even in a high temperature region in the atmosphere and excellent adhesive strength between the carbonaceous material and an oxidation resistant coating film, and a manufacturing method thereof. SOLUTION: The oxidation resistant carbonaceous material is formed by applying the oxidation resistant coating film (preferably, a laminated body containing a boron-containing layer 2 and an oxide ceramic layer 3) on the surface of a carbonaceous material 1 and the adhesive strength of the oxidation resistant coating film to the surface of the carbonaceous material is >=2 MPa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an oxidation-resistant carbonaceous material and a method for producing the same. More specifically, the present invention relates to an oxidation-resistant carbonaceous material having excellent oxidation resistance even in a high temperature range in the atmosphere and having excellent adhesion strength between a carbonaceous material and an oxidation-resistant film, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, as technological innovation has progressed rapidly, the field of space development such as space planes and space planes, the field of kiln tools used in the presence of oxygen, the field of setters for ceramic capacitors, and wall mounting Large display
In the field of protective glass for plasma televisions and the like, which is known as a light-weight, heat-shock resistant, hard-to-break material, it is substantially oxidized in air at a high temperature of 600 ° C. or higher, preferably 1000 ° C. or higher. There is a keen need for the emergence of materials that do not.

In such a situation, Japanese Patent Application Laid-Open No. 6-9269
Japanese Patent Application Laid-Open Publication No. H11-163873 proposes a carbonaceous material having a boron-containing layer (oxidation-resistant film) formed on the surface of the carbonaceous material and having excellent oxidation resistance at high temperatures. However, in the carbonaceous material described in JP-A-6-9269, in addition to being unable to maintain oxidation resistance for a long time, the surface state of the carbonaceous material is not controlled, and the acid resistance depends on the surface state. There is a problem that the chemical properties vary.

On the other hand, Si ₃ N ₄ containing relates to semiconductor processing member formed with corrosion-resistant coating, the SiC between the glassy carbon substrate and Si ₃ N ₄ layer having a set surface to a predetermined surface roughness A member has been proposed in which a layer is formed so that the Si ₃ N ₄ layer does not peel off from the glassy carbon base material (Japanese Patent Application Laid-Open No. Hei 4-345019).

[0005]

However, the setting of the surface roughness of the carbon base material (0.1 μm to 150 μm) of the member in JP-A-4-345019 discloses that the porosity is 0.1% or less as a corrosion-resistant film. Si is a dense film of
Although it is in an appropriate range for a semiconductor processing member using C and Si ₃ N ₄ , as an oxidation resistant film as in the present invention, for example, a boron-containing layer and an oxide ceramic layer (porosity of 0.5 to This is not necessarily appropriate in the case of a carbonaceous material using a film having a low density of about 10%). When the average surface roughness is less than 2 μm, the film is easily peeled,
Further, when the average surface roughness exceeds 20 μm, the undulation of the surface is too large, and it becomes difficult to form a film having a constant thickness.
Since it is necessary to control the film thickness at the peaks and valleys on the surface of the carbonaceous material at a constant level, there has been a problem that the cost increases as the number of steps increases.

The present invention has been made in view of the above-described problems, and has excellent oxidation resistance even in a high temperature region, and has excellent adhesion strength between a carbonaceous material and an oxidation resistant film. It is an object of the present invention to provide a carbonaceous material and a method for producing the same.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, for example, by controlling the average surface roughness of a carbonaceous material to a specific range, etc. It has been found that the above object can be achieved by setting the adhesive strength of the carbonaceous material to the surface in a specific range, and completed the present invention.

That is, the present invention provides the following oxidation-resistant carbonaceous material.

[1] An oxidation-resistant carbonaceous material in which an oxidation-resistant film is coated on the surface of a carbonaceous material, wherein the adhesion resistance of the oxidation-resistant film to the surface of the carbonaceous material is 2 MPa. An oxidation-resistant carbonaceous material characterized by the above.

[2] The surface of the carbonaceous material is 2 μm
The oxidation-resistant carbonaceous material according to the above [1], which is controlled to have an average surface roughness of ｍ20 μm.

[3] The oxidation-resistant film comprises a boron-containing layer containing at least one boron compound selected from the group consisting of carbides, oxides and nitrides of boron (B), and an oxide ceramic layer. The oxidation-resistant carbonaceous material according to the above [1] or [2], which is a laminated body containing the same.

[4] The oxidation-resistant carbonaceous material according to any one of [1] to [3], wherein the boron-containing layer contains boron carbide.

[5] The oxide ceramic layer is made of aluminum, silicon, zirconium, magnesium,
The oxidation-resistant carbonaceous material according to any one of the above [1] to [4], comprising at least one layer containing an oxide of at least one element selected from the group consisting of yttrium, titanium, and calcium.

[6] The oxidation resistance according to any one of [1] to [5], wherein the boron-containing layer and the oxide ceramic layer are formed by coating the surface of the carbonaceous material by plasma spraying. Carbonaceous material.

[7] A method for producing an oxidation-resistant carbonaceous material in which an oxidation-resistant film is coated on the surface of a carbonaceous material,
After controlling the adhesive strength of the oxidation resistant film to the surface of the carbonaceous material to be 2 MPa or more, the surface of the carbonaceous material is coated with the oxidation resistant film. A method for producing a carbonizable material.

[8] The method of controlling the adhesion strength of the oxidation-resistant film to the surface of the carbonaceous material to be 2 MPa or more, has a method of controlling the average surface roughness of the carbonaceous material to 2 μm.
[7] which is obtained by controlling the thickness to [20 μm].
3. The method for producing an oxidation-resistant carbonaceous material according to item 1.

[9] The oxidation-resistant carbonaceous material according to [7] or [8], wherein the method of controlling the average surface roughness of the carbonaceous material to 2 μm to 20 μm is by an abrasive polishing method. Material manufacturing method.

[10] The oxidation-resistant film comprises a boron-containing layer containing at least one boron compound selected from the group consisting of carbides, oxides and nitrides of boron (B), and an oxide ceramic layer. The method for producing an oxidation-resistant carbonaceous material according to any one of the above [7] to [9], wherein the laminate is a laminate including:

[11] The oxidation-resistant carbonaceous material according to any of [7] to [10], wherein the method of coating the surface of the carbonaceous material with the oxidation-resistant film is by plasma spraying. Material manufacturing method.

[0020]

Embodiments of the present invention will be specifically described below with reference to the drawings.

The oxidation-resistant carbonaceous material of the present invention is an oxidation-resistant carbonaceous material obtained by coating the surface of a carbonaceous material with an oxidation-resistant film, and the surface of the oxidation-resistant film, Is characterized by an adhesive strength of 2 MPa or more.

Examples of the carbonaceous material used in the present invention include carbon fibers. Such a carbon fiber can be used irrespective of its production method and raw materials. In actual use, carbon fibers are formed into a predetermined shape using a binder or the like. A C / C composite is preferred from the viewpoint of durability. Further, a composite material in which the C / C composite is impregnated with Si may be used. As such a composite material impregnated with Si, a Si—SiC-based composite material and a SiC-based composite material described later can be suitably used. In the present invention, the term “carbonaceous material” means a concept including not only carbon fibers themselves but also C / C composites containing carbon fibers. In addition, the C / C composite is impregnated with a predetermined amount of metallic silicon, and is a specially processed carbonaceous material, ie, a Si—SiC-based composite material and a SiC-based composite material according to the present invention. include.

As shown in FIGS. 1 to 3, the oxidation-resistant carbonaceous material of the present invention is not substantially oxidized even in the atmosphere at a high temperature of 600 ° C. to 1200 ° C. Here, FIG. 1 is a cross-sectional view schematically showing a state of the oxidation-resistant carbonaceous material of the present invention under a temperature condition of about room temperature, and FIG. FIG. 3 is a cross-sectional view schematically showing a state in a temperature condition up to the vicinity, and FIG.
It is sectional drawing which shows typically the state at the time of more than 600 degreeC of the oxidation resistant carbonaceous material of this invention.
That is, as shown in FIG. 1, in the oxidation-resistant carbonaceous material of the present invention, a surface of a carbonaceous material 1 is covered with a laminate including a boron-containing layer 2 and an oxide ceramic layer 3.
The example shown in FIG. 1 shows a case where the oxide ceramics layer 3 has microcracks 4a and contains silica. As shown in FIG. 1, when the temperature condition is about room temperature (oxidation condition), there is no major problem with respect to the oxidation resistance. However, as shown in FIG. The liquid phase 5 of boron oxide is retained at the interface between the oxide-containing layer 2 and the oxide-containing layer 3, soaks into the cracks 4 b generated in the boron-containing layer 2, and functions to seal the cracks 4 b. Further, as shown in FIG. 3, when the temperature exceeds about 600 ° C., the silica of the oxide ceramics layer 3 becomes a liquid phase 6 and diffuses toward the boron-containing layer 2 side, and cracks generated in the boron-containing layer 2 4b to prevent oxidation by acting to seal the cracks 4b. Here, “not substantially oxidized” means that when the sample is held for at least 24 hours in the atmosphere at 600 to 1200 ° C., the increase or decrease in weight is 0.5% or less.

The oxidation-resistant film used in the present invention includes, for example, a boron-containing layer containing at least one boron compound selected from the group consisting of carbides, oxides and nitrides of boron (B); And a laminate including a ceramic layer. The order of lamination of these layers can be appropriately selected depending on the desired performance, use conditions, and the like. A layer other than the above, for example, a glass layer may be provided between the above layers.

The at least one boron compound selected from the group consisting of carbides, oxides and nitrides of boron (B) includes, for example, borate glass, borosilicate glass, boron nitride, boron carbide and the like. it can.
Above all, boron carbide is preferable from the viewpoint that the liquid phase generated from the boron-containing layer is easily retained.

The boron-containing layer is usually preferably formed directly on the layer near the surface of the carbonaceous material, preferably on the innermost layer, that is, on the surface of the carbonaceous material having a predetermined shape. With this configuration, even if a crack or the like occurs for some reason in the oxidation-resistant film formed on the outermost surface, the crack is sealed by the self-healing function of the boron-containing layer as described above. Therefore, peeling is prevented,
The carbonaceous material will be protected from oxidation. If desired, a primer layer, a layer made of ceramics, or the like may be provided between the boron-containing layer and the surface of the carbonaceous material as the base material.

The boron-containing layer may be provided on the outermost layer depending on the use mode of the carbonaceous material.
For applications that are exposed to oxidizing atmospheres above
It is preferable to form an oxide ceramic layer or a glass layer on the outermost surface.

The thickness of the boron-containing layer is from 10 μm to 500 μm.
μm, preferably 50 μm to 200 μm. 10μ
If it is less than m, it is difficult to form a boron-containing layer as a uniform continuous layer. Further, even if a boron-containing layer is formed with a thickness exceeding 500 μm, improvement in oxidation resistance cannot be expected, and it is not economical because the boron-containing material is expensive.

The boron-containing layer may be formed by directly applying to the surface of the material, or may be formed by thermal spraying or a CVD method. It may be formed by plasma spraying a boron-containing material on the surface of the carbonaceous material.

As the oxide ceramic layer, the second layer
group a, group IIIa, group IIIb, group IVa, group I
Oxides of elements of Group Vb, Group Va, and Group VIa can be given. Above all, those containing as a main component an oxide of at least one element selected from the group consisting of aluminum, silicon, zirconium, magnesium, yttrium, titanium and calcium are preferred. In particular, a composite oxide containing silicon is preferable. Since the ceramic layer has a high elastic modulus, a high thermal stress is likely to be generated even if the coefficient of thermal expansion is close. In order to reduce thermal stress, it is preferable to form an oxide ceramic layer having microcracks therein. The microcracks themselves are permeable to oxygen, but by using the boron-containing layer as an inner layer in combination, boron oxide generated by oxidation is retained in the microstructure of the microcracks,
As a result, the effect of backing up the self-healing function of the oxidation-resistant film, which prevents oxygen from entering, is exhibited.

When a boron-containing layer, for example, boron carbide is exposed to oxidizing conditions, a boron oxide exhibiting a self-healing function is generated as described above, but the generated boron oxide is not adsorbed on carbon, so that the system It may flow out to the outside, and may not be used as an oxidation-resistant layer. The oxide ceramic layer in which microcracks are present exhibits the effect of preventing the occurrence of the crack and backing up the self-healing function of the oxidation-resistant film. The oxide ceramic layer usually forms a sponge-like structure in which innumerable fine holes are formed, and a boron oxide generated by oxidation is adsorbed to this structure, so-called an oxidation-resistant glass layer is formed. It is formed and exhibits a self-healing function of preventing oxidation of the surface of the substrate made of carbon fibers. A glass or other oxide ceramic layer may be further formed on such a sponge-like oxide layer. Thereby, further oxidation resistance can be exhibited. In addition, between the boron-containing layer and the oxide ceramic layer, and / or between the boron-containing layer and a layer made of glass formed as necessary,
The value of the ratio of the thermal expansion coefficients between the layers (the boron-containing layer / the oxide ceramic layer (layer made of glass)) is preferably 1/2 or less from the viewpoint of preventing the occurrence of thermal stress.

As the oxide ceramic layer, a layer made of glaze may be formed. 600 ° C for glaze layer
Is preferable because the oxidation resistance at a high temperature exceeding the above can be further ensured. As the glaze, a glass glaze is preferably used.

In the present invention, the adhesive strength of the oxidation resistant film to the surface of the carbonaceous material is 2 MPa or more. If the adhesive strength is less than 2 MPa, it is not possible to effectively prevent the oxidation resistant film from peeling off from the surface of the carbonaceous material. The test method for evaluating the adhesive strength in the present invention will be described later.

As described above, there is no particular limitation on the means for controlling the adhesion strength of the oxidation-resistant film to the surface of the carbonaceous material to 2 MPa or more. For example, the average surface roughness of the carbonaceous material is controlled by: As a preferred example, control in the range of 2 μm to 20 μm can be mentioned. The method for measuring the average surface roughness in the present invention will be described later. In order to realize the surface roughness of the carbonaceous material as described above, for example, an abrasive grain polishing method (specifically, abrasive grains of silicon carbide are prepared in accordance with JIS R 611, and the abrasive grains are prepared. Is applied to a rotating flat plate together with water, and the surface of the carbonaceous material is ground to a predetermined average surface roughness.

In the method for producing an oxidation-resistant carbonaceous material according to the present invention, after controlling the adhesive strength of the oxidation-resistant coating to the surface of the carbonaceous material to be 2 MPa or more (for example,
After controlling the average surface roughness of the carbonaceous material to 2 μm to 20 μm), the surface of the carbonaceous material is coated with an oxidation-resistant film (for example, selected from the group consisting of carbides, oxides and nitrides of boron (B)). (A boron-containing layer containing at least one type of boron compound, and a laminate including an oxide ceramic layer are preferable).

Specifically, after the carbonaceous material as the base is processed into a desired shape according to the final use, the average surface roughness of the carbonaceous material is adjusted to, for example, 2 μm to 20 μm by the abrasive polishing method. , And a material selected so as to form a desired oxidation-resistant film on the surface can be formed by applying, spraying (for example, plasma spraying), or a CVD method as appropriate. For example, when the boron-containing layer is formed by thermal spraying, the boron-containing material is plasma-sprayed together with an inert gas such as argon. The thermal spraying conditions are not particularly limited, and may be in accordance with ordinary ceramic thermal spraying conditions. The thermal spraying may be performed for each surface of the predetermined shape holding material, or may be performed for all surfaces at the same time. It is preferable to perform this while rotating the shape maintaining material at a constant speed. The thickness of sprayed boron carbide is
As described above, it is usually about 10 μm to 500 μm.

[0037]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited by these Examples.

Examples 1 to 3 As carbonaceous materials, manufactured by Nippon Insulators Co., Ltd.
Silicon carbide abrasive # 10, silicon carbide abrasive # 80, diamond whetstone # 200, diamond whetstone # 1000 using T (product in which C / C composite is impregnated with Si)
Alternatively, samples having different average surface roughness as shown in Table 1 were produced by a finishing method using any one of five types of silicon carbide abrasive grains # 180 or a grinding stone. On its surface,
As the oxidation-resistant film, a first layer was formed by boron plasma as a boron-containing layer, and a second layer was formed of alumina as an oxide ceramic layer by discharge plasma spraying. The thickness was 50 μm for boron carbide and 150 μm for alumina. Porosity is 5
%.

Comparative Examples 1 to 2 The same procedures as in Examples 1 to 3 were carried out except that the average surface roughness of the carbonaceous material was changed to that shown in Table 1.

Evaluation Method The evaluation of the present invention was performed by an oxidation resistance test and an adhesive strength test. The method for measuring the average surface roughness and the above two test methods are shown below.

1. Average surface roughness measurement It was measured in accordance with JIS B0601.

2. Oxidation resistance test The test was performed for 100 hours in the atmosphere under the conditions of exposure to 600 ° C. and 800 ° C. That is, the test sample was placed in an air atmosphere for 60 hours.
After being kept in a chamber at 0 ° C. or 800 ° C. for 100 hours, the weight was measured and compared with the weight before the test, and the reduction rate W ₂ was determined by the following equation. W ₂ = {(W ₁ −W ₀ ) / W ₀ } × 100 where W ₀ is the weight before the oxidation resistance test, W ₁ is the weight after the oxidation resistance test, and W ₂ is the weight (Decrease is distinguished by adding a minus sign in front of the number). In addition, x indicates that a crack was formed in the coating, and x indicates that a small crack was generated (including a case where no crack was generated but the sprayed coating was lifted up in a capillary shape), and a case where no crack was generated Was evaluated with 〇. Table 1 shows the results.

3. Adhesion strength test Measured by a tensile test according to JIS B7721. Table 1 shows the results.

[0044]

[Table 1]

From Table 1, it can be seen that when the boron-containing phase is formed by discharge plasma spraying in a state where the average surface roughness (R _a ) of the carbonaceous material is finished to 2 μm to 20 μm, the adhesive strength becomes 2 MPa or more. In this case, no peeling of the film due to thermal stress was observed even when the film was exposed to a high temperature, indicating that good oxidation resistance was obtained. In Comparative Example 1, the average surface roughness was 21 to 23 μm and the maximum surface roughness was 10
It exceeds 0 μm. When the maximum surface roughness exceeds 100 μm, it takes time to form a film by plasma spraying, and there is a difference of 100 μm between peaks and valleys on the surface of the carbonaceous material, and the formed film thickness is 200 μm (boron carbide 50 μm, (Alumina 150 μm), so that a uniform film thickness could not be obtained. From the above, it is preferable to control the average surface roughness to 20 μm or less and the maximum surface roughness (R _max ) to 100 μm or less.
It has been found that it is better to set the surface roughness to 20 μm or less and the maximum surface roughness to 80 μm or less.

[0046]

As described above, according to the present invention, an oxidation-resistant carbon having excellent oxidation resistance even in a high temperature range and having excellent adhesion strength between a carbonaceous material and an oxidation-resistant film. A quality material and a method for manufacturing the same are provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a state of an oxidation-resistant carbonaceous material of the present invention under a temperature condition of about room temperature.

FIG. 2 is a cross-sectional view schematically showing a state of the oxidation-resistant carbonaceous material of the present invention in a temperature condition up to around 600 ° C.

FIG. 3 is a cross-sectional view schematically showing a state of the oxidation-resistant carbonaceous material of the present invention under a temperature condition exceeding 600 ° C.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Carbonaceous material, 2 ... Boron containing layer, 3 ... Oxide ceramics layer, 4a ... Micro crack, 4b ... Crack,
5 ... Liquid phase of boron oxide permeated into boron-containing layer, 6 ...
Liquid phase of boron oxide and silicon oxide soaked into the boron-containing layer.

Claims (11)

[Claims] 1. An oxidation-resistant carbonaceous material obtained by coating a surface of a carbonaceous material with an oxidation-resistant coating, wherein the adhesion strength of the oxidation-resistant coating to the surface of the carbonaceous material is 2 MPa or more. An oxidation-resistant carbonaceous material, characterized in that: 2. The surface of the carbonaceous material has a thickness of 2 μm to 20 μm.
The oxidation-resistant carbonaceous material according to claim 1, wherein the average surface roughness is controlled to μm. 3. The oxidation-resistant film includes a boron-containing layer containing at least one boron compound selected from the group consisting of carbides, oxides and nitrides of boron (B), and an oxide ceramic layer. 3. The oxidation-resistant carbonaceous material according to claim 1, which is a laminate. 4. The oxidation-resistant carbonaceous material according to claim 1, wherein the boron-containing layer contains boron carbide. 5. The oxide ceramic layer comprises at least one layer containing an oxide of at least one element selected from the group consisting of aluminum, silicon, zirconium, magnesium, yttrium, titanium and calcium. 4. The oxidation-resistant carbonaceous material according to any one of 4. 6. The oxidation-resistant carbonaceous material according to claim 1, wherein the boron-containing layer and the oxide ceramic layer are formed by coating the surface of the carbonaceous material by plasma spraying. . 7. A method for producing an oxidation-resistant carbonaceous material in which the surface of a carbonaceous material is coated with an oxidation-resistant film, wherein the adhesive strength of the oxidation-resistant film to the surface of the carbonaceous material is: A method for producing an oxidation-resistant carbonaceous material, comprising: coating the surface of the carbonaceous material with the oxidation-resistant film after controlling the pressure to 2 MPa or more. 8. A method for controlling the adhesion strength of the oxidation-resistant film to the surface of the carbonaceous material so as to be 2 MPa or more, wherein the average surface roughness of the carbonaceous material is 2 μm to 20 μm.
The method for producing an oxidation-resistant carbonaceous material according to claim 7, wherein the method is performed by controlling the thickness to μm. 9. The carbonaceous material having an average surface roughness of 2 μm
The method for producing an oxidation-resistant carbonaceous material according to claim 7 or 8, wherein the method of controlling the thickness to 20 µm is by an abrasive polishing method. 10. The oxidation-resistant film includes a boron-containing layer containing at least one boron compound selected from the group consisting of carbides, oxides and nitrides of boron (B), and an oxide ceramic layer. 8. A laminate according to claim 7.
10. The method for producing an oxidation-resistant carbonaceous material according to any one of claims 9 to 9. 11. The method for producing an oxidation-resistant carbonaceous material according to claim 7, wherein the method of coating the surface of the carbonaceous material with the oxidation-resistant film is by plasma spraying. .