JPH06199578A - Ceramic-base composite material, its production and ceramic fiber for composite material - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a dense ceramic matrix composite material which can be formed into a complicated shape and has greatly improved fracture toughness and strength, and a method for producing the same. [Structure] A ceramic sintered body in which short fibers 9 or particles are dispersed and strengthened is filled and arranged in an internal space of a three-dimensional woven fabric 5 formed by weaving continuous fibers 1 in three dimensions, and the three-dimensional woven fabric 5 and the ceramic sinter are fired. A ceramics-based composite material characterized by being integrated with a tie, wherein continuous fibers 1 are three-dimensionally woven to form a three-dimensional woven fabric 5 having a predetermined shape.
Short fibers 10 to 30% by weight based on ceramic powder 9
Alternatively, the raw material mixture slurry 7 or the kneaded material is prepared by adding and mixing particles, an additive such as a sintering aid and a binder, and a dispersion medium, and using the cast molding method or the injection molding method, the above three-dimensional shape is obtained. The raw material mixture slurry 7 or the kneaded material is filled in the internal space of the woven fabric 5 to form a shaped body having a predetermined shape, the obtained shaped body is degreased, and further, atmospheric pressure sintering method and atmospheric pressure sintering are performed. It is manufactured by sintering by a hot pressing method, a hot pressing method or a reactive sintering method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic-based composite material, a method for producing the same, and a ceramic fiber for a composite material, and particularly to a ceramic-based composite material excellent in toughness and reliability, a method for producing the same, and a composite excellent in properties. TECHNICAL FIELD The present invention relates to a ceramic fiber for composite material capable of forming a material.

[0002]

2. Description of the Related Art Ceramic raw material powders such as AlN, SiC, Si ₃ N ₄ nitrides, carbides, borides, silicides, etc. are molded into a predetermined shape, and then the obtained ceramic molded body is formed. Sintered ceramics sintered bodies are generally superior in properties such as hardness, electrical insulation, abrasion resistance, heat resistance, and corrosion resistance to conventional metal materials, so that heavy electrical equipment parts, It is used in a wide range of fields as electronic materials and structural materials such as aircraft parts, automobile parts, electronic devices, precision machine parts, and semiconductor device materials.

In addition, as a ceramic structural component which requires high reliability in addition to heat resistance and high temperature strength, such as a ceramic structural component used for gas turbine components, aircraft components, nuclear components, space equipment components and automobile components, inorganic materials are inorganic. A long fiber-reinforced ceramic matrix composite material having a high fracture toughness value, a fracture energy value and the like has been used by reinforcing it with a reinforcing continuous fiber made of a substance or a metal.

Conventionally, the above long fiber reinforced ceramic matrix composite material has been used for hot pressing, organic synthesis, CVI, atmospheric pressure sintering, atmospheric pressure sintering, reaction sintering, capsule HI.
It is manufactured according to various manufacturing methods such as the P method.

[0005]

However, the long-fiber-reinforced ceramic matrix composite material is still an unfinished material because its stable manufacturing technique has not been established. Also, as long fibers that are reinforced materials, the diameter is 10 to 150μ.
Since a continuous fiber having a large size of m is used, it is possible to improve the macro fracture energy, but it cannot be expected to improve the micro fracture toughness value. That is, 0.1μ
There is a drawback in that the toughening function that prevents the generation and development of minute cracks of about m to several μm cannot be expected. Therefore, there was a fear that the initiation of destruction would occur.

Further, the volume ratio of the continuous fiber which can be compounded to obtain high toughness is limited to a considerably low value at the current manufacturing technology level. On the other hand, since the continuous fiber to be composited generally impedes the densification during sintering and may deteriorate the strength of the entire composite, it is only sintered by the atmospheric pressure sintering method or the atmospheric pressure sintering method. It has been difficult to manufacture a composite material that is dense, has high strength, and has high toughness. Therefore, in order to form a dense composite material that satisfies both of the above properties, a method has been adopted in which an external force is applied in a uniaxial direction of the molded body by a hot pressing method to promote the densification and to increase the strength.

However, since the hot pressing method is a method of sintering while pressing a molded body in a uniaxial direction, the shape of a sample that can be sintered is limited to a relatively simple shape such as a flat plate shape. However, it cannot be applied to large products such as turbine rotor blades, vanes, combustors, etc. having different cross-sectional shapes in the pressurizing direction, and there is a problem that the degree of freedom in shape is small.

On the other hand, as a conventional three-dimensional reinforced composite material, C
Those formed by the VI (Chemical Vapor Infiltra-tion) method have also been put to practical use. The CVI method is a method of sequentially precipitating and depositing ceramics to be a matrix in a bundle of fibers (monofilaments) or a gap between preforms to densify the ceramics. However, this CVI method cannot be applied to mass-produced products because a dense composite material cannot be obtained, and a large amount of time is required for the manufacturing process, resulting in high cost. There was a problem that it could not be done.

When a composite material is manufactured by a hot pressing method, a normal pressure sintering method, an atmosphere pressure sintering method, or a capsule HIP method, the matrix is likely to shrink during sintering and the sintering temperature is high. Since it is high and the temperature exceeds the heat resistant temperature of the ceramic fiber in many cases, the composite fiber is apt to be broken or damaged, and the reinforcing effect and toughness improving effect of the fiber are reduced. Further, the capsule HIP method has a drawback that it cannot sufficiently cope with a complicated shape as in the hot pressing method. Further, in the organic compound method, the high temperature strength of the composite material is lowered due to the oxygen component remaining in the matrix. There was a flaw.

On the other hand, the reaction sintering method has the advantage that the matrix does not shrink much during sintering, the deformation is small, and the sintering temperature is relatively low, so that the composite fibers are less damaged. On the other hand, since the free metal component remains, the high temperature strength of the composite material is liable to be lowered, and it is difficult to obtain a sufficiently dense material.

At present, the ceramic fibers constituting the composite material fibers are roughly classified into fibers having a diameter of 100 μm.
And 10 μm levels of fiber are commercially available. However, a large-diameter fiber of 100 μm level can be expected to have a large composite effect, but has a drawback that it is difficult to knit and weave, and there is a problem that it is difficult to design a structure for manufacturing a product-level complex three-dimensional shape product. .

On the other hand, a fine fiber having a level of 10 μm can be easily obtained as a knitted fabric such as a plain weave and a satin weave, and its application as a fiber for a composite material having various complicated shapes has been studied. That is, the above-mentioned 10 μm level thin fiber is
About 500 to 3000 pieces are bundled and fixed with a sizing agent such as epoxy resin or polyimide resin to make a large diameter fiber, and the large diameter fiber is woven into a three-dimensional shape to form a three-dimensional woven fabric of a predetermined shape. . Then, a fixing agent made of resin or the like is applied to the outer surface of the three-dimensional woven fabric to form a composite material fiber having a predetermined shape.

However, when the above-mentioned sizing agent and fixative are used, there is a problem that the step of removing them is indispensable and the manufacturing process of the composite material is complicated. On the other hand, if it is attempted to reduce the amount of the sizing agent or fixative used as much as possible to avoid the above problems, it becomes difficult to maintain a predetermined shape, and there is a problem that dimensional accuracy and product yield are reduced. .

The present invention has been made in order to solve the above-mentioned problems, and it can be formed into a complicated shape without using a hot press sintering method, and the fracture toughness value and the strength are greatly improved. It is an object of the present invention to provide a dense ceramic-based composite material, a method for producing the same, and a composite material fiber capable of forming a composite material having excellent characteristics.

[0015]

In order to achieve the above object, the present inventors have dispersed ceramic fibers or particles in order to further strengthen the matrix that constitutes the internal space of a three-dimensional fabric, while the above fibers or particles are dispersed. We investigated the molding method for effectively filling the ceramics by various experiments and compared the strength characteristics of the obtained ceramic matrix composites. As a result, the ceramic raw material mixture slurry or kneaded material containing the ceramic short fibers or particles of a predetermined shape is filled in the internal space of the three-dimensional fabric by a casting method, an injection molding method, etc. It was found that the matrix can be effectively filled.
Further, when the matrix was filled by the cast molding method, a molded body was obtained in which the ceramic fibers were oriented with respect to the water absorbing surface of the cast mold or the particles were uniformly dispersed in the matrix. By degreasing the molded body and further sintering by atmospheric pressure sintering method, atmospheric pressure sintering method, hot pressing method or reaction sintering method, the matrix part is strengthened compared to conventional materials and both toughness and strength are excellent. It was found that a densified ceramic matrix composite material can be obtained.

Particularly when the reaction sintering method in which the sintering temperature is low and the matrix does not shrink during sintering is applied to combine the fibers, a sizing agent for the fibers and a fixing agent for imparting a three-dimensional shape are left. By using an organic compound having a charcoal ratio of 10% by weight or more and being easily carbonized as a carbon source for the reaction in the calcination step, it is possible to perform a defect in a simple step without providing a step of removing a sizing agent and a fixing agent. It is possible to manufacture a composite material with a small amount of water, and it is also possible to use a sufficient amount of a fixing agent and the like, and it is possible to support a composite material product having a more complicated shape. There was found. The present invention has been completed based on the above findings.

That is, the ceramic-based composite material according to the present invention is characterized in that the interstices of the composite ceramic three-dimensionally reinforced with continuous fibers are dispersed and reinforced with short fibers or particles.

The continuous fiber and the short fiber are carbon silicon fibers (SiC, SiC / C, Si-C-O, Si-Ti-).
C-O), alumina fibers (Al ₂ O _3), zirconia fiber (ZrO _2), selected from carbon fibers, boron fibers, silicon Motokei nitride fiber _{(Si 3 N 4, Si 3} N 4 / C) and mullite fibers Formed from at least one of the following:

The short fibers have a diameter of 1 μm or more and 100 μm.
It is preferable to use a ceramic fiber having a length of 50 m or less and a length of 50 μm or more and 20 mm or less.

Further, in the method for producing a ceramic-based composite material according to the present invention, continuous fibers are three-dimensionally woven to form a three-dimensional woven fabric having a predetermined shape, while 5 to 30% by weight of short fibers are contained in the ceramic powder. Or particles and a sintering aid,
An additive such as a binder and a dispersion medium are added and mixed to prepare a raw material mixture slurry or a kneaded product, and the raw material mixture slurry is added to the internal space of the three-dimensional fabric using a casting method or an injection molding method. To form a molded body of a predetermined shape, degrease the molded body, and sinter it by the well-known atmospheric pressure sintering method, atmospheric pressure sintering method, hot pressing method or reaction sintering method. It is characterized by doing.

Here, as the ceramic raw material powder forming the matrix of the compact and the ceramic sintered body, silicon carbide (SiC), aluminum nitride (Al
N), silicon nitride (Si ₃ N ₄ ), sialon, boron nitride (BN), and other non-oxide general-purpose ceramic materials, and oxides such as alumina, zirconia, titania, mullite, beryllia, cordierite, and zircon. The general-purpose ceramic raw materials of the system are used alone or in combination of two or more. Further, a known and commonly used sintering aid such as yttrium oxide, cerium oxide, magnesium carbonate, calcium carbonate or silicic acid is added to the ceramic raw material powder.

Next, the case where the sintering operation of the molded body is carried out by the reaction sintering method will be described. The reaction sintering method is, for example, a dense Si ₃ N ₄ or S matrix serving as a matrix matrix by a nitriding reaction of raw material Si components or a silicification reaction of carbon.
This is a method of forming iC. For example, when Si ₃ N ₄ is used as the matrix matrix, Si ₃ N ₄ powder and Si ₃
The molded body obtained by impregnating with powder was heated to 1250 to 1400 ° C. in an atmosphere of ammonia or N ₂ to perform nitriding treatment, and Si produced by the nitriding reaction of Si.
It is manufactured by filling the voids of the molded body with ₃ N ₄ .

When SiC is used as the matrix matrix, a woven fabric is impregnated with a mixture of SiC fine powder and C by a slip casting method or the like to obtain a molded body, and then 145
By infiltrating molten Si into the compact at a temperature of about 0 ° C., the infiltrated Si and C in the compact are reacted with each other,
The fiber-reinforced composite material is manufactured by filling the voids with the secondarily generated SiC.

According to the above reaction sintering method, since no sintering aid is used, deterioration of high temperature characteristics is effectively prevented.
Therefore, it is particularly effective as a sintering method for members such as turbine blades that require high-temperature strength.

Since Si ₃ N ₄ and SiC generated by this reaction sintering are generated in a form of filling the voids of the raw material Si particles and the raw material SiC particles, the dimensional change before and after the reaction of the composite material is very small. Also, the reaction temperature for matrix synthesis is low,
Moreover, since the matrix shrinks little, the fiber is less damaged and is effective as a method for producing a composite material having a complicated shape with high dimensional accuracy. In this case, if the fibers and the matrix are firmly bonded, the function of preventing the breakage and crack propagation of the fibers is deteriorated due to the difference in shrinkage, so that carbon, metal, B
It is preferable to form a sliding layer made of N or the like.

Particularly when the composite material is formed by using the reaction sintering method, a large diameter fiber formed by bundling a plurality of continuous fibers with a sizing agent as described in claim 3 is three-dimensionally formed. Three-dimensional woven fabric woven into a shape and this 3
A fiber for composite material, comprising a fixing agent applied to the surface of a woven fabric to maintain the shape of a dimensional woven fabric, wherein the sizing agent and the fixing agent are made of an organic compound having a residual carbon content of 10% by weight or more. It is preferable to use the fibers for composite materials. The organic compound that constitutes the sizing agent or the fixing agent is carbonized in the calcination step and becomes a carbon source for the sintering reaction, and this carbon source reacts with the molten Si component, etc., and SiC ceramics as a matrix is formed. It When the residual carbon content of the organic compound is less than 10% by weight, the carbon source for the sintering reaction becomes insufficient and the amount of reaction reaction of SiC filling the voids around the SiC powder as an aggregate decreases. , A dense composite material cannot be obtained. Therefore, an organic compound having a residual carbon rate of 10% by weight or more is used as a sizing agent and a fixing agent.

The above-mentioned three-dimensional woven fabric is formed to macroscopically reinforce the whole ceramic matrix composite material, and includes carbon silicon, alumina, zirconia, carbon, boron, Si-Ti-C-O, silicon nitride. As shown in FIG. 4, a continuous fiber 1 having a diameter of 3 μm or more and 100 μm or less, which is made of a raw material, mullite, or the like, is woven three-dimensionally in each of the x, y, and z directions to form a predetermined shape close to the final product shape. It That is, the three-dimensional woven fabric is produced in consideration of the array orientation of the fibers assuming a force acting on the composite material from an arbitrary three-dimensional direction.

Fibers or particles to be dispersed in a matrix composed of a ceramics sintered body are added to enhance the toughness of the matrix matrix and to micro-reinforce the whole composite material. Specific examples thereof include silicon carbon. Alumina, zirconia, carbon, boron, Si-Ti-C-
It is preferable to use ceramic short fibers or ceramic particles composed of at least one selected from O, Si ₃ N ₄ and mullite. The content of these ceramic short fibers or ceramic particles is preferably in the range of 5 to 30% by weight with respect to the ceramic raw material powder.

The volume ratio of the ceramic fibers, particles and the three-dimensional woven fabric in the whole composite material is set to 60% by volume or less. If the volume ratio exceeds 60% by volume, it becomes difficult to uniformly arrange the matrix matrix around the respective fibers, particles and the three-dimensional woven fabric, and the strength characteristics of the composite material suddenly deteriorate. The preferable addition amount is in the range of 20 to 50% by volume.

The diameter and the length of the ceramic fiber have a great influence on the dispersibility and orientation of the fiber in the molded body and the strength characteristics of the composite material. In the present invention, the diameter and the length are 1 to 100 μm and the length. Is 50 μm to 20 mm
Use short fibers in the range. When the diameter is less than 1 μm, the reinforcing effect of the matrix matrix is small, and the diameter is 1
With thick fibers exceeding 00 μm, stress due to the difference in thermal expansion easily occurs at the boundary interface between the fibers and the matrix matrix, and cracks and the like easily occur.

When the fiber length is less than 50 μm, the effect of suppressing the progress of cracks is small and the effect of improving the toughness is also small. On the other hand, when a long fiber having a length of more than 20 mm is used, it is difficult to uniformly disperse or orient the fibers in the matrix matrix, and the aggregation of the fibers, which is the starting point of the breakage, is easily formed. Absent.

[0032]

According to the ceramic matrix composite material having the above structure, in addition to the structure in which the entire ceramic matrix composite material is macro-reinforced by the three-dimensional woven fabric, the matrix matrix is further made up of short fibers or particles such as ceramic fibers or whiskers. Since it has a dispersion-strengthened structure, the macro toughening mechanism and the micro toughening mechanism synergistically increase the toughness and strength of the entire composite material.

Further, according to the method for producing a ceramics-based composite material according to the present invention, a raw material mixture slurry or a kneaded material prepared by adding short fibers or particles to a ceramics powder and mixing the mixture is subjected to a casting method or an injection method. It is molded into a predetermined shape by a molding method. Therefore, even when the obtained composite material molded body is degreased and thereafter sintered by the atmospheric pressure sintering method, the atmospheric pressure sintering method, the hot pressing method, or the reaction sintering method, the toughness is excellent and the density is high. A high-strength fiber-reinforced ceramic matrix composite material is obtained.

In particular, except for the hot pressing method, the fiber-reinforced ceramic matrix composite material, which has been difficult to be densified, can be manufactured by the atmospheric pressure sintering method or the atmospheric pressure sintering method.
It is possible to provide a high-density ceramic matrix composite material having a complicated shape with less restrictions on the product shape.

Further, in the case where the fibers are compounded by applying the reaction sintering method in which the sintering temperature is low and the matrix does not shrink during the sintering, as a sizing agent for the fibers and a fixing agent for imparting a three-dimensional shape, The residual coal rate is 10% by weight or more,
By using an organic compound that is carbonized as a carbon source for the reaction in the calcination process, it is possible to manufacture a composite material with few defects by a simple process without providing a removal process of the sizing agent and the fixing agent. Therefore, it becomes possible to use a sufficient amount of the fixing agent and the like, and it is possible to deal with a composite material product having a more complicated shape.

[0036]

EXAMPLES The present invention will be described more concretely based on the following examples.

Examples 1 to 3 Si—C—O continuous fibers (trade name: Nicalon) having a diameter of 15 μm were wound around the outer circumference of the core material 2 as shown in FIG. After forming and extracting the core material 2 from the cylindrical woven fabric 3, a three-dimensional woven fabric 5 having bulged portions 4 at both ends is formed as shown in FIG. The volume ratio of the three-dimensional woven fabric 5 to the entire composite material was 20% by volume. The three-dimensional fabric 5 is formed by weaving the continuous fibers 1 three-dimensionally in the x, y, and z directions as shown in FIG.

On the other hand, α-Si ₃ N having an average particle size of 0.7 μm
5 volume% (Example 1), 10 volume% (Example 2), and 15 volume% of SiC whiskers (trade name: Toka whiskers) having a diameter of 2.5 μm and a length of 50 μm were respectively added to ₄ raw material powders, as shown in Table 1. the volume% (example 3), and 5 wt% with respect to the average particle diameter 1.2μm yttria (Y ₂ 0 ₃₎ powder alpha-Si ₃ N ₄ raw material powder as a sintering aid, sintering 4% by weight of MgAl ₂ O ₄ having an average particle diameter of 1.0 μm as an agent and 5% by weight of a dispersant and a binder component were dispersed in water as a dispersion medium (solvent),
The mixture was mixed in a pot mixer for 15 hours to prepare a uniform aqueous slurry (slip, slurry).

Next, the three-dimensional fabric 5 is set in the cavities in the resin molds 6a and 6b for pressure casting as shown in FIG. 3, and then the water-based sludge 7 is pressed by the pressurizing mechanism 8 to perform the cast molding method. Based on the (slip casting method), each of the above water-based sludges 7 was poured into the resin molds 6a and 6b at a casting pressure of 20 kg / cm ² to prepare dumbbell-shaped molded bodies. Next, after each molded body was naturally dried, it was degreased at a temperature of 600 ° C. for 2 hours in an N ₂ gas atmosphere, and then 1 atm respectively.
Of 2 hours pressureless sintering at a temperature 1700 ° C. in an N ₂ gas atmosphere to prepare a Si ₃ N ₄ group composite material according to Examples 1-3.

Examples 4 to 6 As shown in Table 1, a SiC raw material powder having an average particle size of 0.6 μm was chopped Si-Ti-having a diameter of 10 μm and a length of 2 mm.
5% by volume (Example 4), 10% by volume (Example 5) and 15% by volume (Example 6) of C short fibers (trade name: Tyranno), respectively, and boron (B) as a sintering aid. A raw material mixture containing 1% by weight of SiC raw material powder, 2% by weight of carbon black (C) as a sintering aid, and 5% by weight of a dispersant and a binder was used as a dispersion medium (solvent). Examples 1 to 1 except that they were dispersed in water and mixed in a pot for 15 hours to prepare a uniform slurry (slip, slurry).
In the same manner as in No. 3, sludge was cast into the inner space of the three-dimensional woven fabric and molded to prepare a SiC compact of the same size. Next, this SiC
After the molded body is naturally dried, the temperature is 600 ° C in N ₂ gas atmosphere.
After degreasing for 2 hours at 3 atm (Example 4),
6 atm (Example 5) and 9 atm (Example 6) were subjected to atmospheric pressure sintering at a temperature of 1900 ° C. for 4 hours in an argon gas atmosphere to produce SiC fiber-reinforced SiC matrix composite materials according to Examples 4 to 6.

Comparative Example 1 A slurry was obtained by casting sludge into the inner space of a three-dimensional woven fabric in the same manner as in Example 1 except that the matrix was formed of only Si ₃ N ₄ without adding short fibers of SiC whiskers. After the molded body is naturally dried, the temperature is 600 ° C in N ₂ gas atmosphere.
After degreasing for 2 hours at room temperature, sintering was carried out at a temperature of 1700 ° C. in a N ₂ gas atmosphere of 1 atm for 2 hours under normal pressure.
_{A 3} N ₄ matrix composite was produced.

Comparative Example 2 A sludge containing SiC whiskers was cast into a resin mold for pressure casting in the same manner as in Example 1 except that a three-dimensional woven fabric made of continuous SiC fiber was not used, and the obtained molded body was naturally formed. After drying, degreasing was performed in an N ₂ gas atmosphere at a temperature of 600 ° C. for 2 hours, and then in a 1 atm argon gas atmosphere at a temperature of 170.
By pressureless sintering at 0 ° C. for 2 hours, a Si ₃ N ₄ based composite material according to Comparative Example 2 was manufactured.

The density, the three-point bending strength and the fracture toughness value K _IC of each of the ceramic matrix composite materials according to Examples 1 to 6 and Comparative Examples 1 and 2 thus prepared were measured and shown in the right column of Table 1 below. The results shown were obtained.

[0044]

[Table 1]

As is clear from the results shown in Table 1, an embodiment having a structure in which a three-dimensional woven fabric formed by weaving continuous fibers in a three-dimensional manner is used to macroscopically reinforce it while a ceramic short fiber is used to microreinforce the matrix Examples 1-6
It was confirmed that the fiber-reinforced ceramic matrix composite material of No. 1 has extremely excellent characteristics in three-point bending strength and fracture toughness as compared with Comparative Examples 1 and 2.

On the other hand, as shown in Comparative Example 1, the ceramic-based composite material of Comparative Example 1 in which the matrix is not reinforced by the short fibers has no micro-reinforcing effect by the short fibers, so that the strength and fracture toughness values are relatively high. Fell to.

Further, as shown in Comparative Example 2, the ceramic matrix composite material of Comparative Example 2 which does not use the three-dimensional woven fabric has no macro reinforcing effect by the three-dimensional woven fabric, so that the strength and fracture toughness are further increased as compared with Comparative Example 1. The value has dropped.

Next, the fiber-reinforced ceramic matrix composite material produced by the reaction sintering method will be described with reference to Examples 7 to 8 and Comparative Examples 3 to 4.

Example 7 SiC powder as a matrix constituent and SiC /
A composite material according to Example 7, which was reinforced with a unidirectional laminated structure using C fiber, was manufactured by the following procedure.

That is, as a starting material for the matrix,
Carbon black as a carbon source and α- as an aggregate
A mixture of SiC powder and an organic binder which becomes a carbonization source by being carbonized at a high temperature was used. By uniformly wet mixing these raw materials in a solvent, a slurry (slurry) is obtained.
Was prepared.

On the other hand, with respect to the matrix raw material powder, 40
Vol% SiC / C fibers are arranged in one direction, and a fixing agent (polyimide resin: residual carbon content 15% by weight) is applied to the surface to form a sheet, and a laminate of this sheet is formed by a pressure casting machine. While being placed in the resin mold, the above slurry was held for 5 minutes at a molding pressure of about 30 kg / cm ² and filled to obtain a molded body. Further, after drying the molded body, it is baked (calcined) in vacuum at a temperature of about 1000 ° C. to cure the molded body, and at the same time, the sizing agent, the fixing agent and the organic binder applied to the fibers are carbonized to form a carbon source. By doing so, a carbide was formed.

Next, in the reaction sintering operation, the above-mentioned carbide was placed in contact with the above-mentioned carbide on an alumina board in which about 1.2 times the amount of Si powder necessary for silicidation was put in advance, and it was placed in a vacuum or argon. In a gas atmosphere, temperature 1400-
The raw material carbon black was silicified by heating at 1450 ° C. for 30 minutes to prepare a SiC / C fiber-reinforced SiC matrix composite material according to Example 7.

Example 8 SiC powder as a matrix constituent and a diameter of 10
A bundle of 500 μm Si—C—O continuous fibers bundled together and fixed with a sizing agent (polyimide resin: 15% by weight of residual carbon) to have a large diameter made of Si—C—O continuous fibers. Example 8 in which a three-dimensional laminated structure is reinforced by using
The composite material according to 1. was manufactured by the following procedure.

That is, as the starting material of the matrix, a mixture of carbon black as a carbon source, α-SiC powder as an aggregate, and an organic binder which becomes a carbonization source by being carbonized at a high temperature was used. A slurry (slurry) was prepared by uniformly wet mixing these raw materials in a solvent.

On the other hand, with respect to the matrix raw material powder, 30
A volatilized Si-C-O fiber knitted fabric was wound, and a fixing agent (polyimide resin: 15% by weight of residual carbon) was applied to the surface of the woven fabric to retain its three-dimensional shape, thereby preparing a fiber for a composite material. Next, this composite material fiber was placed in a resin mold of a pressure casting molding machine, and the slurry was held at a molding pressure of about 30 kg / cm ² for 5 minutes to fill it to form a molded body. After drying this molded body, the temperature is about 100 in vacuum.
At the same time as baking (calcination) at 0 ° C. to cure the molded body,
A carbonized material was formed by carbonizing the sizing agent, the fixing agent and the organic binder to which the fibers were applied as a carbon source.

Next, in the reaction sintering operation, the above-mentioned carbide was placed on an alumina board in which about 1.2 times the Si amount necessary for silicidation was put in advance, and the carbide was placed in a vacuum or an argon gas atmosphere. Temperature 1400 to 1450 ℃ 3
The raw material carbon black was silicified by heating for 0 minutes to prepare a Si—C—O fiber reinforced SiC group composite material according to Example 8.

Comparative Example 3 The matrix is SiC and the ceramic fiber is S
A composite material according to Comparative Example 3 was prepared by performing the same procedure as in Example 7 except for the following points to obtain a composite material reinforced with a unidirectionally laminated structure using iC / C fibers.

That is, 40 vol% Si of the matrix
C / C fibers were arranged in one direction, a sheet was prepared using a sizing agent and a fixing agent, and the sheets were laminated to prepare a fiber for composite material. A commercially available epoxy resin (residual carbon ratio: 3% by weight) was used as the sizing agent and the fixing agent. Further, before molding the composite material fibers by a pressure casting machine, the fibers were held at a temperature of 700 ° C. for 1 hour in N ₂ gas to remove the sizing agent and the fixing agent of the fibers.

Comparative Example 4 The matrix is SiC and the ceramic fiber is S
In order to obtain a composite material in which a knitted fabric made of i-C-O continuous fibers is reinforced with a three-dimensional laminated structure using (plain weave),
A composite material according to Comparative Example 4 was prepared by the same procedure as in Example 8 except for the following points.

That is, Si of 30 vol% of the matrix
A -C-O fiber was wound and a three-dimensional shape was retained by using a sizing agent and a fixing agent to prepare a fiber for composite material. A commercially available epoxy resin (residual carbon ratio: 3% by weight) was used as the sizing agent and the fixing agent. In addition, before molding the above composite material fibers by a pressure casting machine, N ₂
Fiber sizing and fixatives were removed by holding in gas at a temperature of 700 ° C. for 1 hour.

The densities of the respective fiber-reinforced SiC-based composite materials according to Examples 7 to 8 and Comparative Examples 3 to 4 thus prepared were measured, and 3 × 4 × 40 mm test pieces were prepared from each composite material. Room temperature (RT) and 13 for test pieces
The three-point bending strength and the fracture toughness value K _IC at 00 ° C. were measured and the results shown in Table 2 below were obtained. The fracture toughness value was measured according to the SEPB method.

[0062]

[Table 2]

As is clear from the results shown in Table 2, according to the composite materials of Examples 7 to 8, the organic compounds having a high residual carbon rate were used as the sizing agent and the fixing agent, and were positively incorporated in the matrix. By forming a carbon source, Si produced by reaction around SiC particles as aggregate
It is formed so that C is filled. Therefore, it was found that a composite material having high strength and large fracture toughness value can be obtained even when a product having a complicated three-dimensional shape is manufactured.

On the other hand, in the composite materials of Comparative Examples 3 to 4, it was confirmed that the carbon source for the reaction sintering was insufficient, the voids were less filled, and the strength and toughness values were relatively lowered. Was done.

In the above examples, Si ₃ N ₄ or SiC is used as the ceramic raw material for forming the matrix, and the SiC fiber (Si) is used as the ceramic fiber.
C whiskers, Si-C-O chops, Si-Ti-C
However, the present invention is not limited to the above raw materials. That is, the results shown in Table 1 are obtained even when Al ₂ O ₃ , AlN or the like is adopted as the ceramic raw material and alumina fiber, zirconia fiber, boron fiber, Si ₃ N ₄ fiber or mullite fiber is adopted as the ceramic fiber. It was confirmed by an experiment that the same densification effect and toughness effect as described in (4) above are exhibited.

With regard to the molding method, by adopting the casting molding method or the injection molding method, it is possible to mass-produce a so-called near net shape molded body having a complicated shape close to the final product shape. Even if there was, it was possible to efficiently produce a densified fiber-reinforced ceramic matrix composite material.

[0067]

As described above, according to the ceramic-based composite material and the method for producing the same according to the present invention, in addition to the structure in which the entire ceramic-based composite material is macro-reinforced by the three-dimensional woven fabric, a matrix matrix is further used as a ceramic material. Since it has a micro-dispersion-reinforced structure with short fibers or particles such as fibers and whiskers, the macro toughening mechanism and the micro toughening mechanism synergistically increase the toughness and strength of the entire composite material. Can be improved.

A raw material mixture slurry or kneaded material prepared by adding and mixing short fibers or particles to ceramic powder is molded into a predetermined shape by a casting method or an injection molding method. A material compact can be efficiently obtained. Therefore, the obtained composite material molded body is degreased, and thereafter, a normal pressure sintering method, an atmosphere pressure sintering method,
Even when sintered by a hot pressing method or a reaction sintering method, a dense and high-strength fiber-reinforced ceramic matrix composite material is obtained, which is excellent in toughness.

In particular, except for the hot pressing method, the fiber-reinforced ceramic matrix composite material, which has been difficult to be densified, can be manufactured by using the atmospheric pressure sintering method or the atmospheric pressure sintering method.
It is possible to provide a high-density ceramic matrix composite material having a complicated shape with less restrictions on the product shape.

By using the above molding method,
A so-called near net shape molded body having a shape close to the final product shape can be obtained, and the secondary processing of the composite material becomes extremely easy.

In particular, when the fibers are compounded by applying the reaction sintering method in which the sintering temperature is low and the matrix does not shrink during sintering, the fibers remain as a sizing agent and a fixing agent for imparting a three-dimensional shape. With a carbon content of 10% by weight or more, and by using an organic compound that is carbonized as a carbon source for the reaction in the calcination step, it is possible to eliminate defects by a simple step without providing a step of removing a sizing agent and a fixing agent. It becomes possible to manufacture a small amount of composite material, and it becomes possible to use a sufficient amount of a fixing agent and the like, and it becomes possible to cope with a composite material product having a more complicated shape.

[Brief description of drawings]

FIG. 1 is a perspective view showing a method for forming a three-dimensional fabric used in the present invention.

FIG. 2 is a perspective view showing a shape example of a three-dimensional fabric used in the present invention.

FIG. 3 is a cross-sectional view showing an example of a method for manufacturing a ceramics-based composite material according to the present invention.

FIG. 4 is a perspective view showing a structure of a three-dimensional fabric.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Continuous fiber 2 Core material 3 Cylindrical woven fabric 4 Bulging part 5 Three-dimensional woven fabric 6a, 6b Resin mold for pressure casting 7 Aqueous slurry (slurry of raw material mixture) 8 Pressurizing mechanism 9 Short fiber

Claims (3)

[Claims] 1. A ceramic-based composite material, characterized in that the interstices of a composite ceramic three-dimensionally reinforced with continuous fibers are dispersed and reinforced with short fibers or particles. 2. A raw material mixture slurry is prepared by weaving continuous fibers in a three-dimensional manner to form a three-dimensional woven fabric having a predetermined shape, and by adding and mixing 10 to 30% by weight of short fibers or particles to a ceramic powder. Prepared, to form a molded body of a predetermined shape by filling the internal space of the three-dimensional fabric with the raw material mixture slurry, the resulting molded body further normal pressure sintering method, atmosphere pressure sintering method, A method for producing a ceramic-based composite material, which comprises sintering by a hot pressing method or a reactive sintering method. 3. A fiber for a composite material, to which at least one of a sizing agent for bundling a plurality of monofilaments and a fixing agent necessary for imparting the shape of a two-dimensional three-dimensional woven fabric or a product is added, wherein the sizing agent and the fixing agent are fixed. A ceramic fiber for a composite material, wherein the agent comprises an organic compound having a residual carbon rate of 10% by weight or more.