JP2001302373A - Carbon fiber reinforced carbon composite and method for producing the same - Google Patents

Abstract

(57) [Summary] The present invention relates to a carbon fiber excellent in oxidation resistance and endurance.
It is an object to obtain a fiber-reinforced carbon composite. The surface of a carbon fiber reinforced carbon composite material (12) is
CaB during high temperature oxidation₄O ₇Or CaB₂O₄Acid resistance
Formation of calcium boride 13 that forms a fluoride film
A carbon fiber reinforced carbon composite 11 characterized by the following.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is particularly applicable to the fields of sliding materials of Concorde, nose cones and leading edges of space shuttles, structural materials of fuel engines, medical materials such as artificial roots, bones, joints and the like. The present invention relates to a carbon fiber reinforced carbon composite having excellent oxidation resistance and a method for producing the same.

[0002]

2. Description of the Related Art As is well known, carbon fiber reinforced carbon composite materials have excellent high-temperature strength and are therefore expected as high-temperature strength materials. However, since this material is composed entirely of carbon, it is oxidized in an oxidizing atmosphere of 500 ° C. or higher, and its characteristics cannot be utilized at an ultra-high temperature.

[0003] Therefore, in order to improve oxidation resistance, chemical resistance and the like, conventionally, ceramics have been coated on a carbon fiber reinforced carbon composite material. By the way, this ceramic coating is performed by a vapor phase chemical vapor deposition (CVD: Che).
physical vapor deposition method) is one of the most main methods. However, although this CVD method has advantages and disadvantages and can obtain a thick film, it is difficult to apply it to a material having a complicated shape.

[0004] In recent years, as international efforts have been made to advance into space, demand for carbon fiber reinforced carbon reinforced carbon composite materials having oxidation resistance has been increasing.

[0005]

SUMMARY OF THE INVENTION Since the first invention has been made in view of such circumstances, the acid resistance of CaB ₄ O ₇ or CaB ₂ O _{4 on} at least the surface of the carbon fiber reinforced carbon composite material during high-temperature oxidation. An object of the present invention is to provide a carbon fiber reinforced carbon reinforced carbon composite having excellent oxidation resistance and endurance by adopting a structure in which calcium boride that forms a oxidized film is formed.

In a second aspect of the present invention, the carbon fiber reinforced carbon composite material is immersed in a solution of CaB ₆ powder dispersed in an organic solvent, impregnated, degreased, and baked. An object of the present invention is to provide a method for producing a carbon fiber reinforced carbon reinforced carbon composite in which the same effect as in the first invention is obtained by forming calcium boride on the surface.

In a third aspect of the present invention, a carbon fiber reinforced carbon composite material is set in a container containing a liquid in which calcium boride powder is dispersed in an organic solvent, and then the composite material is subjected to cold isostatic pressing. Provided is a method for producing a carbon fiber reinforced carbon reinforced carbon composite which is excellent in oxidation resistance and endurance by forming calcium boride at least on the surface and which can be applied to a material having a complicated shape. With the goal.

[0008] A fourth aspect of the present invention is the same as the first aspect of the invention in that a calcium boride composite sample obtained by adding a chromium compound to calcium boride is formed on the surface of a carbon fiber reinforced carbon composite material. It is an object of the present invention to provide a carbon fiber reinforced carbon reinforced composite that provides an effect.

[0009] A fifth invention is a carbon fiber reinforced carbon composite material, after impregnated by immersion in a liquid dispersed in an organic solvent CaB ₆ composite sample, the carbon fiber reinforced carbon composite material subjected to degreasing treatment An object of the present invention is to provide a method for producing a carbon fiber reinforced carbon reinforced composite having the same effects as in the first invention by forming a calcium boride composite sample on the surface of the composite.

A sixth aspect of the present invention is a method of setting a carbon fiber-reinforced carbon composite material in a container containing a liquid in which a calcium boride composite sample powder obtained by adding a chromium compound to calcium boride is dispersed in an organic solvent. Forming a calcium boride composite sample on at least the surface of the composite sample powder by cold isostatic pressing to produce a carbon fiber reinforced carbon reinforced composite having the same effect as the third invention. The purpose is to provide.

[0011]

The carbon fiber reinforced carbon composite according to the first invention is characterized in that at least the surface of the carbon fiber reinforced carbon composite material is exposed to CaB ₄ O ₇ or Ca
It is characterized in that it has a structure in which calcium boride for forming an oxidation-resistant film made of at least one of B ₂ O ₄ is formed.

[0012] The method for producing a carbon fiber reinforced carbon composite according to the second invention is characterized in that the carbon fiber reinforced carbon composite material is impregnated by immersing it in a liquid in which calcium boride powder is dispersed in an organic solvent. And decalcifying to form calcium boride on the surface of the carbon fiber reinforced carbon composite material.

[0013] The method for producing a carbon fiber reinforced carbon composite according to a third aspect of the invention is a method of setting a carbon fiber reinforced carbon composite material in a container containing a liquid in which calcium boride powder is dispersed in an organic solvent. Calcium boride is formed on at least the surface of the composite material by cold isostatic pressing.

According to a fourth aspect of the present invention, there is provided a carbon fiber reinforced carbon composite having a structure in which a calcium boride composite sample obtained by adding a chromium compound to calcium boride is formed on the surface of a carbon fiber reinforced carbon composite material. It is a carbon fiber reinforced carbon composite characterized by the following.

[0015] The method of producing a carbon fiber-reinforced carbon composite according to the fifth invention, the carbon fiber reinforced carbon composite material, CaB ₆
The composite sample is immersed in a liquid dispersed in an organic solvent to perform impregnation, followed by degreasing to form a calcium boride composite sample on the surface of the carbon fiber reinforced carbon composite material.

In a sixth aspect of the present invention, there is provided a method of manufacturing a carbon fiber reinforced carbon composite, comprising: dispersing a carbon fiber reinforced carbon composite material in an organic solvent by mixing a calcium boride composite powder obtained by adding a chromium compound to calcium boride; After setting in a container containing the mixed solution, a method for producing a carbon fiber reinforced carbon composite, comprising forming a calcium boride composite sample on at least the surface of the composite sample powder by cold isostatic pressing. is there.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

In the present invention, a carbon fiber reinforced carbon composite material (hereinafter, simply referred to as a composite material) is produced as follows. First, two-way woven fabric such as plain weave, satin weave, twill weave, one-way oriented material, three-way oriented material, n-directional oriented material, carbon fiber such as felt, rattan (tow), phenol resin, urea resin, melamine Thermosetting resin such as resin and furan resin,
A prepreg is formed by impregnating and applying a binder made of a thermoplastic resin such as carbon black, tar or pitch. Subsequently, the molded body is formed by heating and pressing, and the binder is completely cured by heat treatment of the molded body. Next, the composite material is formed by firing using a conventional method and, if necessary, graphitizing.

In the present invention, the carbon fiber reinforced carbon composite
(Hereinafter simply referred to as a composite) is at least a composite material.
Characterized by having calcium boride formed on the surface
You. Here, calcium boride is CaB at the time of high temperature oxidation.
₄O₇Or CaB₂O ₄Or CaB₄O₇
And CaB₂O₄Of forming an oxidation resistant film consisting of both
Have quality. In the present invention, the oxidation resistant film includes
If it is formed only on the surface of the composite material,
If it is formed by impregnating the surface of the composite material,
Is impregnated not only on the surface of the composite material but also inside the composite material
Including the case where it is formed. Therefore, the above formation is
At least one of coated and impregnated on the surface of the composite material
Mean one.

In the present invention (first invention), “high temperature” during high-temperature oxidation means a temperature in the range of approximately 500 ° C. to 1500 ° C. In the case of CaB ₂ O ₄ , the pressure is generally 800 at 1 atmosphere. ° C, and 8 if the pressure exceeds 1 atm
Means 00 ° C to 1000 ° C. In the case of Cr ₂ O ₃ , “high temperature” means a temperature in the range of 1000 ° C. to 1200 ° C. Therefore, depending on the temperature, an oxidation resistant film made of only CaB ₂ O ₄ may be formed, an oxidation resistant film made of only Cr ₂ O ₃ may be formed, or an oxidation resistant film made of both may be formed.

In the present invention, examples of the organic solvent include polyethylene glycol. The temperature of the degreasing treatment varies depending on the type of the organic solvent. For example, in the case of polyethylene glycol, 300 to 800 ° C.
And preferably 400 to 600 ° C. here,
If the temperature is lower than 300 ° C., carbides may remain in the composite material. If the temperature is higher than 800 ° C., the organic component may rapidly evaporate and pores may be formed in the composite material.

According to the present invention, calcium boride is formed in a composite material which is oxidized in an oxidizing atmosphere of 500 ° C. or more because the constituent materials are all carbon.
A composite having excellent oxidation resistance can be obtained which can prevent oxidation which is a problem in an ultra-high temperature environment. Further, in order to impregnate the composite material with calcium boride or the like, cold isostatic pressing (CIP: Cold Isostatic Pres) is used.
By using the method s), even if the composite material has a complicated shape, the calcium boride isotropically impregnates the composite material, so that the calcium boride layer can be formed evenly.

[0023]

EXAMPLES Examples of the present invention will be described below together with the manufacturing method. It should be noted that the materials, numerical values, and the like of each member described in the following examples are merely examples, and do not specify the scope of the present invention.

Example 1 FIG. 1 shows a carbon fiber reinforced carbon composite (composite) 1 according to Example 1 of the present invention. The composite 1 includes a carbon fiber reinforced carbon composite material (composite material) 2
And the calcium boride 3 formed on the surface of the composite material 2. Here, the calcium boride 3 is converted to CaB ₄ O ₇ or CaB ₂ O during high-temperature oxidation.
₄ or a property of forming an oxidation-resistant film composed of both CaB ₄ O ₇ and CaB ₂ O ₄ .

As described above, the composite according to the first embodiment is
Is formed on the surface of the composite material and the composite material 2, and
CaB at the time of conversion₄O₇Or CaB₂O₄Or
CaB ₄O₇And CaB₂O₄Oxidation resistant film consisting of both
And calcium boride 3 forming
Therefore, oxidation resistance which can be a problem in an ultra-high temperature environment can be prevented.
A composite having excellent oxidizability can be obtained.

Next, a method for producing the composite according to the first embodiment will be described.

First, a composite material 2 is prepared in advance. The composite material 2 is formed, for example, by forming a prepreg by impregnating and applying a binder composed of phenol resin, carbon black, tar, and pitch to carbon fibers of a plain weave bidirectional woven fabric, and molding by heating and pressing. After the binder is completely cured by heat treatment, the molded body is fired by a conventional method.

Next, calcium boride powder having a particle size of about 10.0 μm was dispersed in polyethylene glycol (organic solvent) having a viscosity of 6 to 9 Pa · s to obtain a dispersion. Next, this dispersion was impregnated with the composite material 2 fired at a maximum processing temperature of 2000 ° C., and vacuum impregnation was performed in a vacuum desiccator. Subsequently, a degreasing treatment was performed at 300 ° C. so that the polyethylene glycol was completely evaporated, and a composite 1 in which the entire surface was uniformly coated with the calcium boride powder 3 was prepared.

The evaluation of the oxidation resistance of the composite material provided with the coating of the oxidation resistant film produced by the above method was carried out by a temperature increase oxidation using a differential thermal analyzer and a constant temperature oxidation experiment using an electric furnace. And evaluated from the relationship between the heating temperature, the heating time, and the change in mass. As shown in FIG. 2, the heating rate in the heating oxidation experiment was 15 ° C./mi up to 500 ° C.
n, and the subsequent temperature was 2 ° C./min. The temperature range in the constant temperature oxidation experiment was 700 to 1500 ° C.

As shown in FIG. 1, the carbon fiber reinforced carbon composite according to the first embodiment forms a oxidized film of CaB ₄ O ₇ or CaB ₂ O _{4 on} the surface of the composite material 1 during high-temperature oxidation. It is configured to be coated with calcium chloride 2. In the composite having such a configuration, the composite material 1 that is oxidized in an oxidizing atmosphere of 500 ° C. or more is immersed in a liquid in which calcium boride powder is dispersed in an organic solvent,
The calcium boride can be coated by completely evaporating the organic solvent after the impregnation.
CaB ₄ O ₇ or CaB produced by oxidation of this coating
The oxidation resistance of ₂ O ₄ (at high temperature) can greatly improve the oxidation resistance of the composite.

In fact, when the change in weight of the carbon fiber reinforced carbon composite (C / C composite) according to the example and the conventional C / C composite not containing calcium boride with increase in temperature was examined, the figure shows that: The result shown in FIG. 3 was obtained. In FIG. 3, curve (a) shows the case of the C / C complex of the present invention, and curve (b) shows the case of the conventional C / C complex. From FIG.
It is clear that the weight of the composite material having calcium boride formed on the surface thereof is less than that of the conventional material. As a result, it has been found that the C / C composite according to the present invention has improved oxidation resistance as compared with the related art.

Example 2 FIG. 3 shows a carbon fiber reinforced carbon composite (composite) 11 according to Example 2 of the present invention. The composite 11 includes a carbon fiber reinforced carbon composite material (composite material) 12 and a calcium boride composite sample 13 formed on the surface of the composite material 12. Here, the calcium boride composite sample 13 is obtained by adding a chromium compound to calcium boride.

As described above, the composite 1 according to the above-mentioned Example 2 was used.
Reference numeral 1 denotes a composite material 12 and a composite sample 13 formed on the surface of the composite material 12 and obtained by adding a chromium compound to calcium boride. Therefore, it is possible to obtain a composite having excellent oxidation resistance which can prevent oxidation which is a problem in an ultra-high temperature environment.

Next, a method for producing the composite according to the second embodiment will be described.

First, the composite material 12 is prepared in advance. The composite material 12 is formed by, for example, forming a prepreg by impregnating and applying a binder made of phenol resin, carbon black, tar, and pitch to carbon fibers of a plain weave bidirectional woven fabric, and applying heat and pressure. After the binder is completely cured by heat treatment, the molded body is fired by a conventional method.

Next, a calcium boride composite sample having a particle size of about 10.0 μm was dispersed in polyethylene glycol (organic solvent) having a viscosity of 6 to 9 Pa · s to obtain a dispersion.
Next, this dispersion was impregnated with the composite material 12 fired at a pore treatment temperature of 2000 ° C., and vacuum impregnation was performed in a vacuum desiccator. Subsequently, a degreasing treatment was performed at 300 ° C. so that the polyethylene glycol was completely evaporated, and a composite 11 in which the entire surface was uniformly coated with a coating layer made of calcium boride powder was produced.

The evaluation of the oxidation resistance of the composite 11 provided with the oxidation-resistant coating produced by the above method was carried out by performing a temperature-rise oxidation using a differential thermal analyzer and a constant-temperature oxidation experiment using an electric furnace. And evaluated from the relationship between the heating temperature, the heating time, and the change in mass. The heating rate in the heating oxidation experiment was 5
15 ° C / min up to 00 ° C and 2 ° C thereafter
/ Cm. The temperature range in the constant temperature oxidation experiment was 700
Performed at ~ 1500C.

The carbon fiber reinforced carbon composite 11 according to the second embodiment has a configuration in which a composite sample 13 obtained by adding a chromium compound to calcium boride is formed on the surface of a composite material 12 as shown in FIG. I have. Composite 11 having such a configuration
In the above, the composite material 12, which is oxidized in an oxidizing atmosphere of 500 ° C. or more, is immersed in a liquid in which calcium boride powder is dispersed in an organic solvent, impregnated, and then the organic solvent is completely evaporated. Can coat calcium boride. The oxidation resistance of the composite 11 can be greatly increased by the oxidation-resistant barrier of CaB ₄ O ₇ , CaB ₂ O ₄ , and Cr ₂ O ₃ generated by oxidation of the coating.

(Embodiment 3) Referring to FIG. Example 3
Shows an example of forming calcium boride on the surface of a carbon fiber reinforced carbon composite material by the CIP method.

First, the viscosity in the container (not shown) of 6 to
9 Pa · s polyethylene glycol (organic solvent)
For example, calcium boride (CaB ₆ ) having a particle size of about 10.0 μm and a concentration of 3% is added and mixed well. Next, this mixed solution is put together with a carbon fiber reinforced carbon composite material (composite material) in a latex rubber bag 23 in a pressure vessel 22 containing water 21, and after vacuum degassing, the mouth of the bag 23 is closed. close. Subsequently, the cylinder 26 with the pipe 25 interposed with the valve 24 was moved in the direction of arrow X with the valve 24 closed, and pressure was applied isotropically to the mixed solution in the bag 23 to produce a composite. Here, the pressurizing condition is, for example, pressure: 1 to 2 t.
on / cm ² , time: 1 to 10 minutes (preferably 2 to 5 minutes)
Min).

As described above, according to Example 3, since calcium boride is formed on the surface of the carbon fiber reinforced carbon composite material by the CIP method, for example, even if the composite material has a complicated shape, The calcium boride can penetrate evenly and form calcium boride on the surface of the composite material.

In the third embodiment, the case where calcium boride, ethylene glycol and a composite material are contained in a bag of latex to produce a composite has been described. However, the present invention is not limited to this. Even if ethylene glycol and the composite material are directly charged, the production of the composite can be realized.

(Example 4) This Example 4 is similar to Example 3 except that a calcium boride composite sample obtained by adding a chromium compound to calcium boride was used instead of calcium boride. The composite sample was formed on the surface of the reinforced carbon composite material.

According to the fourth embodiment, similarly to the third embodiment, the composite sample can be uniformly formed on the surface of the composite material having a complicated shape.

[0045]

As described in detail above, according to the present invention,
By employing a structure in which calcium boride or a calcium boride composite sample is formed on the surface of a carbon fiber reinforced carbon composite material, a carbon fiber reinforced carbon reinforced carbon composite having excellent oxidation resistance and endurance can be provided.

Further, according to the present invention, by impregnating the surface of a carbon fiber reinforced carbon composite material with calcium boride or a calcium boride composite sample by the CIP method, it is excellent in oxidation resistance and endurance, and is complicated. It is possible to provide a method for producing a carbon fiber reinforced carbon reinforced carbon composite applicable to a shape material.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a carbon fiber reinforced carbon composite according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between temperature and time of the composite in an evaluation test of the oxidation resistance of the composite according to the present invention.

FIG. 3 is a graph showing a weight change characteristic with temperature of the carbon fiber reinforced carbon composite of FIG. 1 and a conventional composite.

FIG. 4 is a sectional view of a carbon fiber reinforced carbon composite according to a second embodiment of the present invention.

FIG. 5 is an explanatory view of a method for producing a carbon fiber-reinforced carbon-reinforced composite according to Example 3 of the present invention.

[Explanation of symbols]

 1, 11: carbon fiber reinforced carbon composite, 2, 12: carbon fiber reinforced carbon composite, 3: calcium boride, 13: calcium boride composite sample, 22: pressure vessel, 24: valve, 26: cylinder.

Claims (6)

[Claims] At least a surface of a carbon fiber reinforced carbon composite material is subjected to CaB ₄ O ₇ or CaB ₂ O during high-temperature oxidation.
_4. A carbon fiber reinforced carbon composite having a structure in which calcium boride for forming an oxidation-resistant film is formed. 2. A carbon fiber reinforced carbon composite material is immersed in a liquid in which calcium boride powder is dispersed in an organic solvent to be impregnated, and then degreased to form a borane on the surface of the carbon fiber reinforced carbon composite material. A method for producing a carbon fiber reinforced carbon composite, wherein calcium fluoride is formed. 3. A carbon fiber-reinforced carbon composite material is set in a container containing a liquid in which a calcium boride powder is dispersed in an organic solvent, and then a cold isostatic pressing method is applied to at least the surface of the composite material. A method for producing a carbon fiber reinforced carbon composite, wherein calcium fluoride is formed. 4. A carbon fiber reinforced carbon composite, wherein a calcium boride composite sample obtained by adding a chromium compound to calcium boride is formed on the surface of a carbon fiber reinforced carbon composite material. 5. The carbon fiber reinforced carbon composite material is immersed in a liquid obtained by dispersing a calcium boride composite sample powder in an organic solvent, impregnated, and then degreased to obtain a surface of the carbon fiber reinforced carbon composite material. A method for producing a carbon fiber reinforced carbon composite, comprising forming a calcium boride composite sample on a substrate. 6. A carbon fiber reinforced carbon composite material is set in a container containing a liquid in which a calcium boride composite sample powder obtained by adding a chromium compound to calcium boride is dispersed in an organic solvent, and then cooled in a cold state. A method for producing a carbon fiber reinforced carbon composite, comprising forming a calcium boride composite sample on at least the surface of the composite sample powder by a hydraulic molding method.