JPH07223875A - Production of fiber-reinforced ceramic composite material - Google Patents

Abstract

PURPOSE:To provide a manufacturing method capable of producing a fiber- reinforced ceramic composite material without performing interfacial coating in a shorter time and obtaining it at a lower cost than by a conventional method. CONSTITUTION:Reinforcing fibers 10 are gathered to form fiber bundles. The bundles are woven to form a woven cloth-laminated article 12. The woven cloth-laminated article 12 is placed in a reduced pressure atmosphere and a gaseous raw material is supplied to this atmosphere. By the reaction of the gaseous raw material, a ceramic material for a matrix is accumulated on the surface of the reinforcing fibers to form an accumulation layer 18. Subsequently, the treated woven cloth-laminated article is impregnated into a polymer for ceramic production and consecutively sintered to form a sintered layer 22 on the periphery of the reinforcing fibers. Thus, a ceramic-based matrix 23 comprising the accumulation layer 18 and the sintered layer 22 is formed on the periphery of the reinforcing fibers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a ceramic composite material having a structure in which ceramics are reinforced with fibers.

[0002]

2. Description of the Related Art One of the major drawbacks of ceramics known to exhibit high strength at high temperatures is that they have lower toughness and lower fracture strain and fracture toughness than metal materials and the like. Therefore, for the purpose of improving the reliability of this type of ceramics in terms of structural materials, fiber reinforced ceramics (FRC = Fiber Reinfo) having whiskers or ceramic fibers mixed in a ceramic matrix to enhance toughness
rced Ceramics) is under development. FRC is generally classified into two types, short fiber reinforced type and continuous fiber reinforced type. As an example of a typical production method of continuous fiber reinforced FRC, CVI method (Chemical Vapor Infiltration:
A manufacturing method using a vapor phase growth method) is known.

According to this manufacturing method, a woven fabric (woven fabric laminated body) such as a two-dimensional woven fabric or a three-dimensional woven fabric is produced by weaving reinforcing fibers, and the woven fabric laminate formed body is placed in a reduced pressure atmosphere, and in a reduced pressure atmosphere. Raw material gas to heat the material at high temperature, or apply a charge to a heated and decompressed atmosphere to generate plasma to cause the reaction of the raw material gas, and the reaction product is vapor-deposited on the surface of the reinforcing fiber to be strengthened. This is a method of producing an FRC by forming a matrix by covering the outer periphery of the fiber with a vapor deposition deposit.

As another method for producing a continuous fiber type FRC, after manufacturing the woven fabric laminated compact, the woven fabric laminated compact is immersed in a polymer for producing ceramics,
A method for manufacturing an FRC by firing a woven fabric laminate molded body impregnated with a polymer to form a ceramic matrix outside the reinforcing fibers (PIC method: PolymerInf
iltration Conversion) is also carried out.

[0005]

However, in order to carry out the manufacturing method using the vapor phase growth method, it takes a long time to deposit reaction products in a reduced pressure atmosphere.
There is a problem that it takes a long period of 3 to 8 months to manufacture the C member. Furthermore, even if the matrix is deposited over such a long time, there is a problem that it is difficult to form the matrix in a completely dense state around the entire reinforcing fibers. Further, as the ceramic fiber used as the reinforcing fiber, a SiC fiber or the like is usually used,
Since this kind of reinforcing fiber itself is expensive, there is a problem that the conventional FRC becomes an extremely expensive material in combination with the prolongation of the manufacturing period.

[0006] In such a background, the present inventors have
As a result of earnest studies on each of the RC manufacturing method and the actually manufactured FRC, the following findings were obtained. First, in general, a woven laminated body has a structure as shown in FIG. This woven laminated body A is made of SiC.
A large number of fiber bundles 2 formed by bundling reinforcing fibers 1 such as
It is formed by being woven three-dimensionally or three-dimensionally. Therefore, in the inside of the woven laminated body A, the fine pores 4 existing between the bundled reinforcing fibers 1 ... and the textured portion existing between the woven fiber bundles 2 ... And a discontinuous gap 5 is formed. In the usual woven fabric laminated body A, the size of the pores 4 is about several μm to 10 μm, which is the same as the diameter of the reinforcing fibers 1, and the thickness of the gap 5 is the same as the thickness of one woven fabric. About several hundred to 500 μm, and the diameter of the gap 5 is about several mm to 3 m, which is about the same as the texture of the fiber bundle.
It is about m.

When the CVI method is applied to the woven laminated body A having such a structure, the reaction conditions in the woven laminated body are uniform over a certain portion, and the surface of the reinforcing fiber 1 is Considering that the ceramics precipitate from the portion at a constant rate, the fine pores 4 inside the fiber bundle can be filled with the matrix, but the large voids 5 outside the portion cannot be filled with the matrix by the CVI method. Considered difficult. On the other hand, as an application of the CVI method, a temperature gradient CVI method in which a temperature distribution is applied to a woven laminated laminate and precipitation is performed while changing the temperature distribution state has been carried out. The fiber reinforced ceramic composite produced by this method is used. Also in the material, there were a part with a high density of the matrix and a part with a low density.

Further, when manufacturing this type of FRC by the CVI method, in order to prevent the reaction between the reinforcing fiber and the ceramic material deposited around it, it is necessary to coat the outer periphery of the reinforcing fiber in advance. ing. Further, even when the FRC is manufactured by the PIC method, the outer periphery of the reinforcing fiber may be previously coated. However, since the coating process for the reinforcing fibers is performed by using a method such as CVD (Chemical Vapor Deposition), it takes a long time to perform the coating itself.
It has also been a factor in further increasing the RC manufacturing time.

The present invention has been made in view of the above circumstances, and it is possible to omit the interfacial coating and to manufacture a fiber-reinforced ceramic composite material in a shorter period of time than before,
It is an object of the present invention to provide a manufacturing method capable of obtaining a fiber-reinforced ceramic composite material at a lower cost than ever before.

[0010]

In order to solve the above-mentioned problems, the invention of claim 1 forms a fiber bundle by assembling reinforcing fibers, and weaves the fiber bundle to form a woven laminated laminate. This woven laminated body is placed in a reduced pressure atmosphere, and a ceramic material serving as a matrix is deposited on the surface of the reinforcing fibers by the reaction of the raw material gas supplied in the reduced pressure atmosphere to form a deposition layer, and then the woven fabric is formed. A laminated molded body is impregnated with a ceramics-forming polymer, and subsequently fired to form a fired layer around the reinforcing fibers, and a ceramic matrix composed of the deposited layer and the fired layer is formed around the reinforcing fibers. .

In order to solve the above-mentioned problems, the invention according to claim 2 forms a fiber bundle by assembling reinforcing fibers, and weaving the fiber bundle to form a woven fabric laminated body. A method for producing a fiber-reinforced ceramic composite material, in which a body is placed in a reduced-pressure atmosphere, and a ceramic material serving as a matrix is deposited on the surface of a reinforcing fiber by the reaction of a raw-material gas supplied in the reduced-pressure atmosphere, the method comprising: The ceramic material is deposited on the surface of the reinforcing fiber to generate a matrix of the ceramic material in the fine pores between the reinforcing fibers in the fiber bundle in the woven laminated body, and thereafter,
The woven laminated laminate is impregnated with the polymer, the gap between the fiber bundles in the woven laminated laminate is filled with the polymer, and then the mixture is fired to form the impregnated polymer into a matrix.

In order to solve the above-mentioned problems, the invention according to claim 3 is to deposit a ceramic material on the fine pores between the reinforcing fibers in the fiber bundle by the vapor phase growth method according to claim 1 or 2. The ceramic material is deposited until the weight of the woven laminated laminate is increased by 50% or more, and then the woven laminated laminate is impregnated with a polymer.

[0013]

[Function] The reinforcing fibers are formed from the ceramic material by depositing the ceramic material by the reaction of the raw material gas on the woven laminated body formed by weaving the fiber bundle of the reinforcing fibers, impregnating the ceramic forming polymer, and then firing the polymer. A fiber-reinforced ceramic composite material having a structure covered with a matrix is obtained. In this method, the micropores between the reinforcing fibers in the fiber bundle are filled with a considerable amount of ceramic material by the deposition due to the reaction of the raw material gas, and the remaining micropores and the space between the fiber bundles around them are impregnated by the polymer impregnation and firing. The gap is filled with a ceramic material. Therefore, the pores and gaps of the entire woven laminated body are completely filled with the ceramic material, and a strong product can be obtained.

Further, when the ceramic material is deposited on the reinforcing fiber, the deposited layer prevents the reinforcing fiber from reacting with the fired layer obtained by impregnating and firing the polymer around the deposit layer. Therefore, a fiber-reinforced ceramic composite material having high strength can be obtained. Therefore, it is possible to omit the coating treatment which is conventionally required for the reinforcing fibers.

On the other hand, it takes a considerably long time to fill a large number of fine pores and a large number of voids in the entire woven laminated body only by the deposition action of the ceramic material due to the reaction of the raw material gas. If a method of forming a ceramic material deposition layer in the pores by reactive deposition of the raw material gas and then filling the surroundings with a polymer and firing to form a fired layer of the ceramic material is much shorter than before. A matrix of ceramic material can be created.
Therefore, the manufacturing time is shortened. Further, if the polymer impregnation is performed after forming the deposited layer of 50% or more of the woven laminated laminate of the reinforcing fiber, a sufficient amount of the deposited layer can be formed around the reinforcing fiber. Since the firing layer is bonded to the fiber, a fiber-reinforced ceramic composite material having sufficient strength can be obtained.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a process chart of an example of the method of the present invention. In order to manufacture a fiber-reinforced ceramic composite material according to the process of this example, first, long-fiber reinforcing fibers are prepared in step 1 and the reinforcing fibers are prepared. In step 2, two-dimensional or three-dimensional weaving is performed to prepare a woven laminated body, and then the woven laminated body is subjected to the CVI method in step 3, and then in step 4, the woven laminated body is impregnated with a polymer. By firing, and then machining in step 5 to form a desired shape,
A fiber-reinforced ceramic composite material (product) 6 can be obtained.

First, the reinforcing fibers prepared in the step 1 should be the same as the reinforcing fibers used in the production of ordinary fiber-reinforced ceramics, such as SiC fibers, alumina fibers, and silicon nitride fibers. it can.
Further, as in this example, as shown in FIG. 2A, the reinforcing fiber 10 may be wound around the bobbin 11 so that it is easy to use. Then, in step 2, a two-dimensional weaving process or a three-dimensional weaving process is performed by a weaving machine to manufacture a woven fabric laminated body 12 having a desired size and shape, for example, shown in FIG. In this example, the reinforcing fiber 10 is used to form a fiber bundle, and the fiber bundle is further woven to form the woven fabric laminated body 12. Therefore, the cross-sectional structure of the woven fabric laminated body 12 is the same as that of the conventional woven fabric shown in FIG. It has the same structure as the fabric laminated body A, and has a structure in which fine pores of several μm unit are formed inside the fiber bundle and gaps of several mm unit are formed between adjacent fiber bundles.

Next, in step 3, the woven laminated body 12 is coated with a ceramic matrix around the reinforcing fibers 10 by using a CVI device 15 as shown in FIG. 2C. It is generated until it increases by about 50%. The CVI device 15 shown in FIG. 2C includes a decompression container 16 and a high-frequency heating coil 1 provided on the outer periphery thereof.
7, the decompression container 16 is connected to a decompression device such as a vacuum pump so that the internal pressure can be adjusted, and further, a gas supply pipe or the like is connected so that the source gas can be supplied inside. Has been done. The high-frequency heating coil 17 is connected to a high-frequency power source and is capable of generating plasma inside the decompression container 16 to thermally decompose the raw material gas supplied into the decompression container 16 to cause a reaction.

In step 3, the woven laminated body 12 is housed inside the decompression container 16 and the inside pressure is reduced to a predetermined pressure by a vacuum pump or the like. Gas supply, high frequency heating coil 17
Is activated and further heated to about 1000 ° C. to form a deposition layer 18 composed of reaction deposits of the source gas on the outer peripheral portion of each of the reinforcing fibers 10 of the woven laminated body 12 (see FIG. 3).
Can be generated. Here, a mixed raw material gas of SiH ₄ gas and CH ₄ gas, or methyltrichlorosilane (MTS), dimethyldichlorosilane, Si
A source gas such as a mixed gas of Cl ₄ and CH ₄ can be used.

Here, as described above, the woven laminated body 12
The reason why the CVI treatment is performed until the weight of the reinforcing fiber 10 increases by about 50% is that the pores in the fiber bundle of the reinforcing fiber 10 can be filled in a considerable amount by this amount of deposition, and the outer peripheral portion of the reinforcing fiber 10 is covered. This is because it takes a considerable amount of time to perform further deposition and the manufacturing time becomes long, and the deposition amount on the reinforcing fiber 10 may be too small if the deposition amount is smaller than this. In the actual manufacturing, for example, about 1/3 of the vapor deposition deposition period performed by the conventional CVI method is performed by the CVI method in the present invention, and the CVI method is stopped at this stage to perform the next step. To move to. Here, since about 40% of the weight of the fiber-reinforced ceramic composite material is usually the reinforcing fiber, it is necessary to treat about 50% of the weight of this kind of reinforcing fiber by the CVI method as described above. About 20% of the total weight of the material will be deposited by the CVI method. More specifically, 2 is added to the surface of the reinforcing fiber 10.
A ceramic material having a thickness of about 3 μm is deposited.

After step 3 is completed, in step 4, the woven laminated body 12 is dipped in a polymer. The dipping device used here is preferably, for example, a decompression container 21 connected to a decompression pump 20 as shown in FIG. The decompression container 21 is filled with the polymer solution 22, and the woven laminated laminate 12 is immersed in the decompressed container 21, and the inside pressure is reduced, so that the polymer solution is filled in the spaces between the fiber bundles inside the woven laminated laminate 12. It can be sufficiently impregnated. The polymer solution used here is a polytitanocarbosilane solution,
Examples thereof include polycarbosilane solution and polysilazane solution.

After this impregnation treatment has been carried out for a required time, the woven laminated laminate 12 is taken out from the decompression container 21 and fired at a desired temperature in a heating furnace or the like to prepare the polymer solution as shown in FIG.
The firing layer 22 is as shown in FIG. The firing temperature is appropriately set depending on the type of polymer used, but is usually 100
The temperature is around 0 ° C. Further, after the firing treatment performed here, the firing layer 22 may be further impregnated with a polymer solution, and further firing treatment may be repeated a necessary number of times.

After the firing work is completed, in the processing step 5, the fired product is machined into a desired shape by machining such as cutting or cutting to obtain the fiber-reinforced ceramic composite material 6. it can. The internal structure of the fiber-reinforced ceramic composite material 6 is as shown in FIG.
A deposition layer 18 made of a ceramic material around the reinforcing fiber 10.
Is formed, a firing layer 22 made of a ceramic material produced by polymer impregnation firing is further formed around the deposition layer 18 of each reinforcing fiber 10, and a matrix 23 composed of the deposition layer 18 and the firing layer 22 is formed. There is.

When the fiber-reinforced ceramic composite material 6 is manufactured by the method described above, the deposition layer 18 which is a part of the ceramic matrix 23 is manufactured by the CVI method, and the remaining part of the firing layer 22 is impregnated with the polymer. Since it is formed by firing, there is an effect that it can be manufactured in a much shorter period than the conventional method in which all the matrices are manufactured by the CVI method. Further, the deposited layer 18 formed by the CVI method prevents the reaction between the reinforcing fiber 10 and the fired layer 22 formed on the outside thereof, so that the strength of the fiber-reinforced ceramic composite material 6 as a whole becomes high. Also, high temperature strength can be obtained as compared with conventional materials. Therefore, the fiber-reinforced ceramics composite material 6 obtained in the present invention is used in applications requiring high strength at high temperatures, for example, aircraft parts such as flaps for aircraft engines and outer wall materials for space vehicles, or
In addition, it can be widely applied as a structural material or an exterior material that requires heat resistance.

"Production Example" A rectangular parallelepiped woven cloth laminate having a width of 3 mm, a height of 100 mm and a length of 200 mm is formed by three-dimensionally weaving a fiber bundle having an outer diameter of 500 μm formed by bundling SiC fibers having a diameter of 8.5 μm. The woven fabric laminated compact is housed in a decompression container, decompressed to 5 Torr, and a source gas of methyltrichlorosilane (MTS) is supplied to the body to form a body.
A deposition process was performed by heating to 00 ° C. When the weight of the woven laminated body is increased by 50%, the woven laminated body is taken out of the decompression container, and then the woven laminated body is immersed in the polytitanosilane solution and baked at 1100 ° C.
Repeated times to obtain a SiC fiber reinforced silicon ceramics composite material. In this manufacturing example, the manufacturing period is 2.
It took 5 months.

Next, the same SiC fiber as described above is used, this SiC fiber is coated with carbon of 0.2 μm in thickness by the CVD method, and further the CVI method is carried out using the same mixed raw material gas as described above. A fiber reinforced ceramic composite sample was produced by producing the entire ceramic matrix. This manufacturing method required 6 months as a manufacturing period. Subsequently, a polymer equivalent to the polymer used in the above example was used to produce the entire ceramic matrix by the PIC method to manufacture a fiber-reinforced ceramic composite material sample. Further, a CVI method was carried out by using the SiC fiber not coated with the above to generate all of the ceramic matrix to manufacture a fiber-reinforced ceramic composite material sample.

FIG. 4 shows the results of comparing the bending strength values of the samples obtained by the above methods. In FIG.
CVI is C using coated SiC fiber
The characteristics of the sample manufactured by carrying out the VI method are shown, and CVI
Is CV using uncoated SiC fiber
The characteristic of the sample manufactured by implementing the method I is shown. As is clear from the results shown in FIG. 4, the sample manufactured by the method of the present invention showed the best bending strength. In particular, it has been revealed that an improvement effect of about 20% can be achieved in terms of fracture toughness, as compared with the high-strength one manufactured by the conventional method. 5 shows the relationship between bending strength and displacement at room temperature of the sample manufactured by the method of the present invention, and FIG.
The relationship between bending strength and displacement when exposed to 0 ° C. atmosphere for 100 hours is shown.

From these results, it is clear that the fiber-reinforced ceramic composite material produced by the method of the present invention exhibits sufficiently high flexural strength at room temperature and excellent strength even at a high temperature of 1300 ° C. It was Further, when the method of the above-mentioned production example is carried out and the deposition layer is deposited on the reinforced fiber by the CVI method, the woven fabric laminate is deposited until the weight thereof increases by 70%, and then the polymer-impregnated firing is performed to form the fiber. A reinforced ceramic composite material was manufactured, but a material having a strength similar to that shown in FIGS. 5 and 6 was obtained.

[0029]

As described above, according to the present invention, ceramics are formed after the deposition layer of the ceramic material is deposited by the reaction of the raw material gas on the woven fabric laminated compact formed by weaving the fiber bundle of the reinforcing fibers. Since the polymer is impregnated and fired to form a fired layer, a fiber-reinforced ceramic composite material having a structure in which reinforcing fibers are covered with a ceramic matrix composed of a deposited layer and a fired layer can be obtained. In addition, the deposited layer prevents the fired layer and the reinforcing fibers from reacting with each other,
As a result, it is possible to obtain a fiber-reinforced ceramic composite material having high strength not only at room temperature but also at high temperature.

Further, in the method of the present invention, by the deposition by the reaction of the raw material gas, it is possible to fill a considerable amount of fine pores between the reinforcing fibers in the fiber bundle with the ceramic material, and by impregnating and firing the polymer, the fibers around it can be filled. The gaps between the bundles can be filled with a matrix of ceramic material. Therefore, the pores and gaps of the entire woven laminated body can be sufficiently filled with the matrix of the ceramic material, so that a fiber-reinforced ceramic composite material having high strength can be obtained.

Further, it takes a considerably long time to fill a large number of fine pores and a large number of voids in the entire woven fabric laminated body only by the deposition action of the ceramic material due to the reaction of the raw material gas, and it is completely filled. However, the matrix of the deposited layer of the ceramic material is formed in the fine pores in the fiber bundle by the reactive deposition of the raw material gas, and the polymer is filled in the gaps between the remaining fine pores and the fiber bundle and fired to make the ceramic material. If the method of forming the matrix of the firing layer is used, the matrix of the ceramic material can be formed in a much shorter time than the conventional method. Therefore, the manufacturing time can be significantly shortened, and the fiber-reinforced ceramics composite material can be provided at a lower cost than before.

Further, if the impregnation of the polymer is carried out after the deposition layer of 50% or more of the woven laminated laminate of the reinforcing fibers is formed by the reaction and deposition of the raw material gas, a sufficient amount of the deposition is provided around the reinforcing fibers. Since a layer can be generated and a fired layer can be formed on this deposited layer and the two can be joined together, a fiber-reinforced ceramic composite material having high strength can be obtained.

[Brief description of drawings]

FIG. 1 is a process drawing showing an example of the method of the present invention.

2A is a perspective view showing a state in which reinforcing fibers are wound around a bobbin, FIG. 2B is a perspective view of a woven laminated body, and FIG.
Is a block diagram showing an example of a CVI device, and (d) is a block diagram showing an example of a decompression container.

FIG. 3 is a partial cross-sectional view of a fiber-reinforced ceramic composite material obtained by the method of the present invention.

FIG. 4 is a diagram comparing bending strengths of a composite material obtained by the method of the present invention and a composite material obtained by a conventional method.

FIG. 5 is a diagram showing bending strength at room temperature of an example of the composite material obtained by the method of the present invention.

FIG. 6 is a diagram showing bending strength at high temperature of an example of a composite material obtained by the method of the present invention.

FIG. 7 is a view showing a cross-sectional structure of a woven fabric laminated body for general fiber reinforced ceramics.

[Explanation of symbols]

 6 ... Fiber reinforced ceramics composite material 10 ... Reinforcing fiber 12 ... Woven laminated molding 16 ... Decompression container 18 ... Deposit layer 22 ... Firing layer 23 ... Matrix

Claims (3)

[Claims] 1. A reinforcing fiber is collected to form a fiber bundle, and the fiber bundle is woven to form a woven fabric laminated molded body. The woven fabric laminated molded body is placed in a reduced pressure atmosphere and supplied into the reduced pressure atmosphere. The ceramic material serving as a matrix is deposited on the surface of the reinforcing fiber by the reaction of the raw material gas thus formed to form a deposited layer, and thereafter, the woven fabric laminated compact is impregnated with the ceramic-forming polymer, and subsequently fired to deposit the deposited layer. By forming a fired layer by polymer firing around the
A method for producing a fiber-reinforced ceramic composite material, comprising forming a ceramic matrix composed of the deposited layer and the fired layer around a reinforcing fiber. 2. Reinforcement fibers are collected to form a fiber bundle, the fiber bundle is woven to form a woven fabric laminated body, and the woven fabric laminated body is placed in a reduced pressure atmosphere and supplied into the reduced pressure atmosphere. A method for producing a fiber-reinforced ceramic composite material, which comprises depositing a ceramic material serving as a matrix on the surface of a reinforcing fiber by the reaction of the raw material gas, wherein the ceramic material is deposited on the surface of the reinforcing fiber by the reaction of the raw material gas. A deposition layer of a ceramic material is generated in the fine pores between the reinforcing fibers in the fiber bundle in the fabric laminated body, and thereafter, the woven fabric laminated body is impregnated with the polymer to fill the woven fabric laminated body with the polymer. After that, it is fired to form a fired layer made of the impregnated polymer,
A method for producing a fiber-reinforced ceramic composite material, which comprises forming a ceramic matrix with the deposited layer and the fired layer. 3. When the ceramic material is deposited on the outer periphery of the reinforcing fiber by the reaction of the raw material gas, the ceramic material is deposited until the weight of the woven fabric laminate is increased by 50% or more, and then the woven fabric laminate is formed. The method for producing a fiber-reinforced ceramic composite material according to claim 1, wherein the molded body is impregnated with a polymer.