JP2955748B2 - Composite ceramics and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a composite ceramic and a method for producing the same, and more particularly to a long fiber reinforced composite ceramic and a method for producing the same.

[0002]

2. Description of the Related Art Ceramics have high strength, high wear resistance,
It has advantages such as high melting point, chemical stability, high corrosion resistance, etc.
It also has the disadvantage of being brittle. In order to overcome this brittleness, various methods for producing a ceramic by compounding with a long fiber have been studied. For example, a method in which an inorganic long fiber such as silicon carbide is produced from an organometallic polymer compound such as polycarbosilane by heat treatment or the like, and a ceramic slurry is impregnated and sintered into a woven fabric using the inorganic long fiber. A method of embedding ceramics in a woven fabric composed of long fibers by a CVI (chemical weber infiltration) method or the like has been proposed (ceramic-based composite material, pp42-60; Agne Shofusha).

[0003]

An inorganic long fiber such as silicon carbide is hard to bend because of lack of flexibility like carbon fiber. For example, it is impossible to tie the inorganic long fiber. Therefore, it has a drawback that it is difficult to produce a woven fabric having a complicated shape. In addition, in the above-described method, since the organometallic polymer compound is made inorganic by heating at a high temperature, and the composite of the mineralized long fiber and the ceramic is taken, a step of heating again at a high temperature to sinter the ceramic is performed. It also has the disadvantage of high cost. Furthermore, when the ceramic molded body containing inorganic long fibers is heated and sintered, the molded body shrinks. At this time, the inorganic long fibers are stretched, so that a tensile stress is generated in the ceramic matrix and cracks are generated. doing.

An object of the present invention is to provide a composite ceramic which can be easily manufactured at a low cost even in a complicated shape, and a method of manufacturing the same.

[0005]

According to the composite ceramics of the present invention, an inorganic filament in which intersecting inorganic filaments are chemically bonded in a ceramic matrix and each inorganic filament has a radius of curvature of 0.5 mm or more. It has a fiber skeleton structure. FIG. 1 shows a schematic view of an example of the composite ceramic of the present invention. Inorganic long fibers 2 and 3 having a radius of curvature of 0.5 mm or more intersecting in the ceramic matrix 1 form a skeletal structure. The portion A where the inorganic long fibers 2 and 3 are in contact has a chemically bonded structure. In this way, since the inorganic long fibers are bonded to form a bridge, the shape becomes like a honeycomb structure by long fiber bundles, the overall toughness can be improved, and the radius of curvature of each inorganic long fiber is reduced to 0. Since it is 0.5 mm or more, it has flexibility, can be easily bent, and can be formed into a complicated shape.

[0006] The composite ceramics according to the present invention also includes:
The inorganic long fiber is made of silicon carbide, Si-CO, silicon nitride, S
i-NO, Si-Ti-CO, Si-Ti-N-
O, Si-Ti-N-CO, aluminum nitride, Al
-NO, Al-Ti-CO, Al-Ti-NO,
Al-Ti-NCO, Si-Al-O, Si-Al
-CO, Si-Al-NO, Si-Al-NC-
O, chromium nitride, Si-Cr-CO, Si-Cr-N
—O, Si—Cr—N—C—O, zirconium nitride, S
i-Zr-CO, Si-Zr-NO, Si-Zr-
It is composed of at least one of N—C—O. Since these inorganic long fibers are all formed with a radius of curvature of 0.5 mm or more, they have flexibility, can be easily bent, and can be manufactured in a complicated shape.

[0007] The composite ceramics according to the present invention further comprises:
Ceramic matrix is Si, Al, Cr, Ti,
It contains at least one of nitrides, carbides, oxides, oxynitrides, and carbonitrides of Zr, Hf, W, and Y. The raw materials for these matrices are nitriding gas,
By reacting with a carbonizing gas or oxidizing gas atmosphere, it is possible to fill the voids of the molded body without causing shrinkage. For sintering of these matrix materials,
Methods such as pressureless sintering, gas pressure sintering, hot press sintering, hot isostatic press sintering, spark plasma sintering, and microwave plasma sintering can be used.

The method for producing a composite ceramic of the present invention comprises:
A step of combining a long fiber of an organometallic polymer compound composed of at least one of one-dimensional orientation, two-dimensional orientation, three-dimensional orientation, and woven fabric with a raw material for forming a ceramic matrix to form a molded body; A step of irradiating the body with one or both of an electron beam and a gamma ray in an inert atmosphere to infusibilize the long fiber, and heating the formed body in an inert atmosphere to densify the ceramic matrix And a process. FIG. 2 shows a process chart of an example of the method for producing a composite ceramic of the present invention. First, one-dimensional orientation,
A long fiber of an organometallic polymer compound comprising at least one of two-dimensional orientation, three-dimensional orientation, and woven fabric is prepared (Step S).
1) From this, a preform molded article such as a three-dimensional woven fabric is produced (step S2), and the preform molded article is compounded with a raw material for forming a ceramic matrix by a method such as impregnation (step S3). Is obtained (step S4). The molded body is irradiated with one or both of an electron beam and a γ-ray in an inert atmosphere to make the long fibers infusible (step S5). After infusibilizing the long fibers, the organometallic polymer is mineralized (step S6), and the compact is heated in an inert atmosphere to densify the ceramic matrix (step S7). Alternatively, after the infusibilization treatment of the long fibers, the inorganic matrix treatment of the organometallic polymer and the heating of the molded body in an inert atmosphere are simultaneously performed to densify the ceramic matrix (step S8). Obtain composite ceramics. According to the method for producing a composite ceramic according to the present invention, it is possible to obtain a composite ceramic which can be easily manufactured at a low cost at a complicated shape.

The obtained inorganic long fiber reinforced composite ceramics has a structure as shown in FIG.
The ceramic matrix compact before densification has a structure as schematically shown in FIG. That is, a preform 8 such as a woven fabric made of metal organic polymer long fibers is compounded in the ceramic matrix raw material powder 7.

The long fiber bundle used in the present invention, in which 500 long fibers composed of a precursor organometallic polymer before being mineralized, are bundled, has a flexibility of a radius of curvature of 0.1 mm or less, and is complicated. It is possible to make a three-dimensional woven fabric of various shapes. The long fiber made of the precursor organometallic polymer may be in the form of a fiber bundle, or may be in the form of a woven fabric such as plain weave, satin weave, mosaic weave, twill weave, woven weave, spiral weave, or three-dimensional weave. And a non-woven fabric.

The method for producing a composite ceramic according to the present invention comprises:
A step of combining a long fiber of an organometallic polymer compound comprising at least one of one-dimensional orientation, two-dimensional orientation, three-dimensional orientation, and woven fabric with a raw material for forming a ceramic matrix to form a molded body; An electron beam and γ
A step of irradiating one or both of the wires while heating in an inert atmosphere to infusibilize the long fibers and at the same time densify the ceramic matrix. As a result, it is possible to obtain a composite ceramic which can be easily formed into a complicated shape at a low cost in a small number of steps as described above.

Further, the method for producing a composite ceramic according to the present invention is a method for forming a long matrix of an organometallic polymer compound comprising at least one of one-dimensional orientation, two-dimensional orientation, three-dimensional orientation and woven fabric, and a ceramic matrix. A step of compounding the raw materials to form a molded body, and applying an electron beam and γ
Irradiating one or both of the wires in an inert atmosphere to infusibilize the long fibers, and subjecting the compact to an atmosphere containing at least one of a nitriding gas, a carbonizing gas, and a silicifying gas. Heating to precipitate the ceramic matrix from the raw material to densify the ceramic matrix. By heating the molded body in an atmosphere containing at least one of a nitriding gas, a carbonizing gas, and a silicidizing gas, the space of the molded body can be filled without shrinkage, and a complicated shape can be obtained without deformation. A composite ceramic having a shape can be obtained.

Further, the method for producing a composite ceramic according to the present invention is a method for forming a long matrix of an organometallic polymer compound comprising at least one of one-dimensional orientation, two-dimensional orientation, three-dimensional orientation, and woven fabric, and a ceramic matrix. A step of compounding the raw materials to form a molded body, and applying an electron beam and γ
One or both of the wires are irradiated while heating in an atmosphere containing at least one of a nitriding gas, a carbonizing gas, and a silicifying gas to infusibilize the long fibers and simultaneously precipitate a ceramic matrix from the raw material. And densifying the ceramic matrix by using this method. Thereby, a composite ceramic having a complicated shape can be obtained in a small number of steps without causing shrinkage.

In the method for producing a composite ceramic according to the present invention, at least one of silicon, titanium, zirconium, chromium and aluminum is used as the organometallic polymer compound. In addition, as the precursor organometallic polymer, various polysiloxane compounds, various polysilane compounds, various polysilazane compounds, various polycarbosilane compounds, various polycarbosilazane compounds, and the like can be used.

Further, in the method for producing a composite ceramic according to the present invention, the organometallic polymer compound comprises boron, beryllium, scandium, vanadium, iron, selenium, strontium, which are sintering aid components of the ceramic matrix.
It further contains at least one of hafnium, molybdenum, tungsten, yttrium, niobium, tantalum, and a rare earth element. By including these, sintering of the ceramic matrix can be promoted.

Further, in the method for producing a composite ceramic according to the present invention, the long fibers obtained after heating may be made of silicon carbide, Si—C
-O, silicon nitride, Si-NO, Si-Ti-CO,
Si-Ti-NO, Si-Ti-NCO, aluminum nitride, Al-NO, Al-Ti-CO, Al
-Ti-NO, Al-Ti-NCO, Si-Al
-O, Si-Al-CO, Si-Al-NO, Si
-Al-N-C-O, chromium nitride, Si-Cr-C-
O, Si-Cr-NO, Si-Cr-NCO, zirconium nitride, Si-Zr-CO, Si-Zr-N
—O, Si—Zr—N—CO—at least one of them. In the portions where these long fibers intersect with each other, there are many portions that are mutually reacted and bonded.

Further, the method for producing a composite ceramic according to the present invention is characterized in that the ratio of long fibers to the ceramic matrix in the composite ceramic obtained after heating is 20:80 to 80: 20% by volume. It is.
Thereby, a composite ceramic having high toughness is obtained.

Further, according to the method for producing a composite ceramic of the present invention, the raw material of the ceramic matrix is Si, Al,
At least one ceramic powder of nitride, carbide, oxide, oxynitride, carbonitride of Cr, Ti, Zr, Hf, W, Y or at least one metal of Si, Al, Cr, Ti, Zr It contains powder. By forming a ceramic matrix from these and reacting with a nitriding gas, a carbonizing gas, or a silicidizing gas atmosphere, it is possible to fill the voids of the compact without shrinkage.

Further, in the method for producing a composite ceramic according to the present invention, the ceramic matrix of the composite ceramic may be:
It is characterized by containing at least one kind of nitride, carbide, oxide, oxynitride and carbonitride of Si, Al, Cr, Ti, Zr, Hf, W and Y. By reacting them with a nitriding gas, a carbonizing gas, or a silicidizing gas atmosphere, it is possible to fill the voids of the compact without causing shrinkage.

Further, in the method for producing a composite ceramic according to the present invention, the precipitate generated during heating may be formed of Si, Al, Cr,
At least one nitride of Ti, Zr, Hf, W, Y;
It is made of carbide, oxide, oxynitride or carbonitride and has a whisker shape or a particle shape with a diameter of 5 nm to 5 μm.

Further, according to the method for producing a composite ceramic of the present invention, the precipitate generated during heating is formed of Si, Al, Cr,
At least one nitride of Ti, Zr, Hf, W, Y;
It is made of carbide, oxide, oxynitride, and carbonitride, and is dispersed in the form of particles in the grains and the grain boundaries of the ceramic matrix. As shown in FIG. 1, these particles 5 and whiskers 6 are dispersed in the ceramic matrix 1. When these particles and whiskers are dispersed in the ceramic matrix while heating, they can be dispersed uniformly, and the toughness of the sintered ceramic can be further increased.

In the method for producing a composite ceramic according to the present invention, when an electron beam is used for infusibilizing the precursor organometallic polymer long fiber, the electron beam acceleration voltage is in the range of 20 kV to 100 MV in an inert gas or vacuum. It is desirable to perform in. If the accelerating voltage is too small, infusibilization is insufficient, and if it is too large, activation may occur. The dose rate is desirably in the range of 1 to 10 ⁵ Gy / s. If the dose rate is too low, it takes a long time for infusibility, and if the dose rate is too high, the precursor is melted and the shape cannot be maintained. As the electron beam irradiation, light in a short wavelength region of 200 nm or less, such as excimer laser light or ultraviolet light, can be used.

Γ is used to make the precursor organometallic polymer long fiber infusible.
When using wires, in an inert gas or vacuum
For example, ⁶⁰ Co can be used as the radiation source. The dose rate is desirably in the range of 1 to 10 ⁵ Gy / s. If the dose rate is too low, it takes a long time for infusibility, and if the dose rate is too high, the precursor is melted and the shape cannot be maintained.

According to the composite ceramics and the method of manufacturing the same according to the present invention, a long fiber reinforced composite ceramic having a complicated shape can be obtained at an unprecedented cost. Composite ceramics can be used for blades, vanes, combustors or shrouds, and nuclear components.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below.

[0026]

Example 1 As an organometallic polymer compound, a diameter of 15 μm was used.
The yarn obtained by bundling 500 m long polycarbosilane long fibers was three-dimensionally woven into a cubic shape having a size of 4 × 4 × 4 cm.
The porosity of the preform is 45%. Next, as a raw material of the ceramic matrix, a silicon powder having a particle size of 0.5 μm and an aqueous solvent were mixed to form a slurry, which was poured into the voids of the preform to produce a molded body. An acceleration voltage of 2 MV, a dose rate of 1 kGy / s and a dose of 20 MGy
The polycarbosilane long fiber in the molded article was made infusible by irradiating an electron beam until the temperature became. Then, after heating to 1300 ° C in an argon atmosphere, 1000 ° C in a nitrogen atmosphere.
To 1400 ° C. at a heating rate of 1 ° C./min to nitride the silicon powder to obtain a silicon nitride ceramic matrix. The shrinkage due to sintering was less than 1%.
As a result, a silicon nitride composite ceramics (porosity: 12 vol%) reinforced with three-dimensional woven Si-CO long fibers was obtained. The ratio of long fiber / silicon nitride matrix is 70 /
30 vol%. At the portions where the three-dimensional woven Si-CO long fibers intersect, they are chemically bonded to form a three-dimensional skeleton. The strength of the obtained composite ceramics is 4
It was 74 MPa, and this strength was maintained from room temperature to 1500 ° C. This composite ceramic has a large destructive work and exhibits a destructive form that does not cause catastrophic destruction.

When polysiloxane long fibers, polysilane long fibers, polysilazane long fibers, or polycarbosilazane long fibers are used in place of the above-mentioned polycarbosilane long fibers, nitriding reinforced by three-dimensional woven ceramic long fibers is similarly used. Silicon composite ceramics (porosity 12 vol%) was obtained.

[0028]

Example 2 As an organometallic polymer compound, a diameter of 15 μm was used.
A preform was manufactured by three-dimensionally weaving a yarn in which 500 polysilazane long fibers were bundled into a moving blade shape of a gas turbine. Next, as a raw material of the ceramic matrix, a silicon powder having a particle diameter of 0.3 μm and an aqueous solvent were mixed to form a slurry, which was poured into the voids of the preform to produce a molded body. An acceleration voltage of 20 MV and a dose rate of 1 kG
irradiate an electron beam at a dose of 40 MGy at y / s,
The polysilazane long fibers in the molded article were made infusible. Then
Heating was performed at a heating rate of 1 ° C./min to 1400 ° C. in a nitrogen atmosphere to nitride the silicon powder to obtain a silicon nitride ceramic matrix. The shrinkage due to sintering was less than 1%. Thereby, silicon nitride composite ceramics (porosity 11v) reinforced with three-dimensional woven Si-NO long fibers
ol%) was obtained. The ratio of long fiber / silicon nitride matrix is 60/40 vol%. Three-dimensional woven Si-N-
At the portions where the O long fibers intersect, there were chemically bonded portions. The strength of the obtained composite ceramics is 5
22 MPa, and maintained this strength from room temperature to 1500 ° C. This composite ceramic has a large destructive work and exhibits a destructive form that does not cause catastrophic destruction. This composite ceramic was assembled in a 1300 ° C. class gas turbine facility and operated for 1000 hours. As a result, no damage was confirmed.

Instead of the above-mentioned polysilazane filaments,
Silicon nitride composite ceramics (porosity: 12 vol%) reinforced with three-dimensional woven ceramic long fibers can be obtained similarly using polysiloxane long fibers, polysilane long fibers, polycarbosilane long fibers, and polycarbosilazane long fibers. Was.

Similarly, in a 1300 ° C. class gas turbine test facility for rotating a turbine by combustion gas in a thermal power plant system, a lining of a combustor constituting a gas turbine, a transition piece for a combustor, a bypass valve,
A turbine rotor blade, a turbine vane, a turbine disk, a spindle bolt, a turbine casing, a shroud, a diffuser cone, a turbine exhaust casing, and an exhaust duct were manufactured by the method of this embodiment. As a result of a running test for 1,000 hours using this test facility, no abnormality was found.
By using the composite ceramics of this example, it was possible to reduce the amount of cooling air, and it was possible to improve the efficiency by 5% or more as compared with the case where metals were used. Also, a regenerative single-shaft gas turbine for cogeneration, a regenerative two-shaft gas turbine for cogeneration, a regenerative two-shaft gas turbine for portable power generation, a gas turbine for aircraft,
It has been confirmed that high efficiency can be achieved by providing the composite ceramics of the present invention in an automobile gas turbine or the like.

[0031]

Example 3 As an organometallic polymer compound, a diameter of 15 μm was used.
A preform was manufactured by three-dimensionally weaving a yarn in which 500 m of polysilazane long fibers were bundled into a stationary blade shape of a gas turbine. Next, as a raw material of the ceramic matrix, a silicon powder having a particle diameter of 0.3 μm and an aqueous solvent were mixed to form a slurry, which was poured into the voids of the preform to produce a molded body. An acceleration voltage of 20 MV and a dose rate of 1 kG
irradiate an electron beam at a dose of 40 MGy at y / s,
The polysilazane long fibers in the molded article were made infusible. Then
Heating at a heating rate of 1 ° C./min to 1400 ° C. in a nitrogen atmosphere by hot isostatic pressing (HIP) at 100 atm to mineralize the polysilazane filaments and nitridize silicon powder to silicon nitride A ceramic matrix was obtained. 1750 °
C was sintered for 5 hours to obtain a silicon nitride composite ceramic.
The shrinkage due to sintering was 12%. As a result, a silicon nitride composite ceramics (porosity 11 vol%) reinforced with three-dimensional woven Si-NO long fibers was obtained. The ratio of long fiber / silicon nitride matrix is 60/40 vol%. At the portions where the three-dimensional woven Si-NO long fibers intersect, there were chemically bonded bonding parts. The strength of the obtained composite ceramics was 748 MPa, and this strength was maintained from room temperature to 1500 ° C. This composite ceramic has a large destructive work and exhibits a destructive form that does not cause catastrophic destruction. This composite ceramic is installed in a 1500 ° C class gas turbine facility,
After operation for 000 hours, it was confirmed that no damage occurred.

[0032]

Example 4 As an organometallic polymer compound, a diameter of 15 μm was used.
The yarn obtained by bundling 500 m long polycarbosilane long fibers was three-dimensionally woven into a cubic shape having a size of 4 × 4 × 4 cm.
The porosity of the preform thus manufactured was 45%.
Met. Next, as a raw material of the ceramic matrix, a silicon powder having a particle size of 0.5 μm and an aqueous solvent were mixed to form a slurry, which was poured into the voids of the preform to produce a molded body. An acceleration voltage of 2 MV and a dose rate of 1
An electron beam was irradiated at a dose of 20 MGy at kGy / s to infusify the polycarbosilane long fibers in the molded product.
Then, after heating to 1300 ° C. in an argon atmosphere by hot isostatic pressing (HIP) at 100 atm, 1 ° C./mi from 1000 ° C. to 1400 ° C. in a nitrogen atmosphere.
Heated at a heating rate of n, the silicon powder was nitrided to obtain a silicon nitride ceramic matrix. This silicon nitride ceramic matrix was sintered at 1750 ° C. for 10 hours to obtain a silicon nitride composite ceramic. As a result, a silicon nitride composite ceramics (porosity 0.5 vol%) reinforced with three-dimensionally woven Si-CO long fibers was obtained. Long fiber /
The ratio of the silicon nitride matrix is 70/30 vol%. At the portions where the three-dimensional woven Si-CO long fibers intersect, there were chemically bonded bonding portions. The strength of the obtained composite ceramics was 674 MPa, and this strength was maintained from room temperature to 1500 ° C. This composite ceramic has a large destructive work and exhibits a destructive form that does not cause catastrophic destruction.

[0033]

Embodiment 5 By the same manufacturing method as in Embodiment 1, SiC, AlN, TiN, BN,
Using a slurry containing 10 vol% of ZrN, Al ₂ O ₃ , and ZrO ₂ , a similar impregnation and heat treatment were performed to produce a long fiber reinforced composite ceramic. As a result, similarly to Example 1, a high-strength composite ceramic having a porosity of 12% or less and a strength at 1500 ° C. equal to or higher than room temperature was obtained. By adding the inorganic particles, the toughness of the ceramic matrix can be improved, and the wear resistance, conductivity, oxidation resistance, and the like can be improved.

[0034]

Embodiment 6 An inorganic compound whisker (diameter 10 μm, length 100 μm) was added to Si powder by the same manufacturing method as in Embodiment 1.
As SiC, AlN, TiN, BN, ZrN, Al ₂
The same impregnation and heat treatment were performed using a slurry containing 10 vol% of O ₃ and ZrO ₂ to produce a long fiber reinforced composite ceramic. As a result, the porosity was 1 as in Example 1.
High-strength composite ceramics having a strength at 1500 ° C. of 2% or less and equal to or higher than room temperature were obtained. By dispersing the whiskers in the ceramic matrix, the toughness of the ceramic matrix itself could be improved. Also, by combining the method of Example 5 and the method of Example 6, the inorganic compound particles and the inorganic compound whiskers could be dispersed in the ceramic matrix.

[0035]

Example 7 An example of producing a fiber-reinforced composite ceramic in which long fibers are oriented in two directions in a ceramic matrix will be described. Here, SiC is used in a silicon nitride matrix.
A method for producing a silicon nitride / SiC fiber reinforced composite ceramic in which fibers are oriented in two directions will be mainly described.

First, a green sheet composed of a reaction sintered silicon nitride matrix component Si powder + SiC powder is prepared. On the obtained green sheet, a bundle of 500 polycarbosilane fibers is oriented as uniformly as possible in one direction, and several layers of the polycarbosilane fibers are laminated so that the polycarbosilane fibers are alternately orthogonal to each other, and pressed at 98 MPa in the laminating direction. A molded article was obtained.
The molded article was irradiated with γ-rays at an acceleration voltage of 3 MV and a dose rate of 2 kGy / s until a dose of 30 MGy was obtained, so that the polycarbosilane long fibers in the molded article were made infusible. Then, after heating to 1300 ° C. in an argon atmosphere,
Heating was performed at a heating rate of 1 ° C./min from 000 ° C. to 1400 ° C. to nitride the silicon powder to obtain a silicon nitride ceramic matrix in which SiC long fibers and SiC particles were dispersed. The shrinkage due to sintering was less than 1%. In the production method according to the present invention, since the linear shrinkage ratio during sintering is small, almost no stress is generated between the fiber bundle and the ceramic matrix, and thereby a high-strength composite ceramic is obtained.

According to the same method, metal powder C other than Si
Using r, Ti, Zr, and Al, other matrix components such as Cr nitride, Ti nitride, Zr nitride, and Al nitride also
In the case of other organometallic precursors as well, a fiber-reinforced composite ceramic in which the fiber bundles are perpendicular to the ceramic matrix in two directions can be produced.

According to this embodiment, by using the reaction sintering method, a high-strength, high-toughness composite ceramic can be obtained without shrinkage. Therefore, two-dimensional fabrics other than three-dimensional fabrics, felts, papers, whiskers,
A dense, high-strength, high-toughness composite ceramic can be obtained without shrinking by using a preform molded body made of a nonwoven fabric or the like.

[0039]

[Embodiment 8] In the above-described embodiment, the nitrided sintering of Si is changed from a nitriding gas to a carbonizing gas atmosphere such as a CO gas atmosphere or a silicidizing gas atmosphere such as silane. Simple substances or composites of carbides, silicides, etc. other than those described above could be produced.

[0040]

Example 9 In Example 7, long fiber reinforced composite ceramics having different fiber contents were produced. As a result, it was found that when the fiber content was less than 20 vol%, the fracture toughness value was not significantly improved, and when the content exceeded 80 vol%, the bonding strength of the ceramic matrix was reduced. Therefore, the fiber content is 20 to 80 vol%,
In particular, 40 to 70 vol% is preferable in terms of achieving both the strength and toughness characteristics.

[0041]

Embodiment 10 An example of manufacturing a gas turbine rotor blade as a part to which the fiber bundle reinforced composite ceramics according to the present invention is applied will be described.

First, a preform molded article for a rotor blade is produced using polytitanocarbosilane long fibers. Si powder (0.3 μm) and titanium carbide powder (1 μm)
m) Impregnated with a slurry consisting of (Si / titanium carbide = 80/20 mass%) and an organic solvent. The molded body was irradiated with γ-rays at an acceleration voltage of 4 MV and a dose rate of 2 KGy / s until a dose of 30 MGy to infusify the polytitanocarbosilane long fibers in the molded body. Then, after heating to 1300 ° C. in an argon atmosphere, 1 hour in a nitrogen + CO atmosphere.
Heating from 000 ° C. to 1400 ° C. at a heating rate of 1 ° C./min to nitride the silicon powder and form Si—Ti—C
A composite ceramic (porosity: 8%) in which -N long fibers and TiN particles of 10 nm to 1 µm were dispersed in the silicon nitride ceramic matrix within the grains and at the grain boundaries was obtained. The shrinkage due to sintering was less than 1%. In the production method according to the present invention, since the linear shrinkage ratio during sintering is small, almost no stress is generated between the fiber bundle and the ceramic matrix, and thereby a high-strength composite ceramic is obtained.

The pores may be filled with silicon nitride by a CVI method or the like to further densify. For example, the above composite ceramics was heated to 1500 ° C., and SiCl and NH ₃ gas were flowed as CVI raw materials to generate Si ₃ N ₄ in pores. The porosity of the obtained long fiber reinforced composite ceramics was 2%. Most of the interfaces between fibers / particles and between particles / particles of the obtained composite ceramics were bonded without any inclusions. The method described above can be applied to the case of matrix components other than the present embodiment, and also to the case of using other fibers and media, and the shape is not limited to the moving blade of the turbine, but may be a stationary blade, a combustor, Various shapes that can be preform molded can be manufactured.

In the above-described process, an organometallic polymer containing Ti was used. Similarly, chromium, zirconium,
Inorganic long fiber reinforced composite ceramics could be obtained even when using organometallic polymer long fibers containing aluminum.

The inorganic filaments obtained in this example are:
Controllable by the starting organometallic polymer and heating atmosphere, silicon carbide, Si—CO, silicon nitride, Si—N
—O, Si—T—C—O, Si—Ti—N—O, Si—
Ti-NCO, aluminum nitride, Al-NO, Al-
Ti-CO, Al-Ti-NO, Al-Ti-N-
CO, Si-Al-O, Si-Al-CO, Si-
Al-NO, Si-Al-NCO, chromium nitride,
Si-Cr-CO, Si-Cr-NO, Si-Cr
—N—C—O, zirconium nitride, Si—Zr—C—
Inorganic long fibers such as O, Si-Zr-NO, and Si-Zr-NCO can be oriented in a ceramic matrix during sintering.

Instead of titanium carbide, Si, Al, C
By adding at least one kind of nitride, carbide, oxide, oxynitride, and carbonitride of r, Ti, Zr, Hf, W, and Y and reacting with the atmosphere during heating, Si, A during heating is added.
a precipitate composed of at least one of nitride, carbide, oxide, oxynitride and carbonitride of l, Cr, Ti, Zr, Hf, W and Y, and having a whisker shape or a particle shape having a diameter of 5 nm to 5 μm. Can be generated.

[0047]

Embodiment 11 Silicon nitride / Si—C obtained in Embodiment 1
-O long fiber composite ceramics was used as a bearing material for a pump. As a result of a sliding test at a speed of 10 m / s and a surface pressure of 50 kg / cm ² , it was found that the fiber provided a lubricating effect and exhibited excellent sliding characteristics. As described above, it was found that the composite ceramics according to the present invention had excellent sliding characteristics because the fibers were added.

[0048]

Example 12 As an organometallic polymer compound, a diameter of 20
A yarn obtained by bundling 500 long polycarbosilane fibers containing 5% yttrium in the side chain of μm was three-dimensionally woven into a cube having a size of 4 × 4 × 4 cm. Next, as a raw material of the ceramic matrix, a silicon powder having a particle size of 0.5 μm and an aqueous solvent were mixed to form a slurry, which was poured into the voids of the preform to produce a molded body. The molded article was irradiated with an electron beam at an acceleration voltage of 5 MV and a dose rate of 2 kGy / s until a dose of 50 MGy to infusify the polycarbosilane long fibers in the molded article. Then, in an argon atmosphere,
After heating to 300 ° C., heating was performed at a heating rate of 1 ° C./min from 1000 ° C. to 1400 ° C. in a nitrogen atmosphere, and the silicon powder was nitrided to obtain a silicon nitride ceramic matrix. This silicon nitride ceramic matrix was sintered at 1750 ° C. for 5 hours to obtain a composite ceramic. Yttrium in the side chain becomes a sintering aid for silicon nitride,
It could be densified. Thereby, three-dimensional woven Si
A silicon nitride composite ceramics (porosity 1.5 vol%) reinforced with -CO long fibers was obtained. The ratio of long fiber / silicon nitride matrix is 80/20 vol%. At the portions where the three-dimensional weave Si-CO long fibers intersect, they were chemically bonded. The strength of the obtained composite ceramics is 6
It was 20 MPa, and this strength was maintained from room temperature to 1500 ° C. This composite ceramic had a large destructive work and exhibited a fracture mode in which no catastrophic fracture occurred.

As shown in this example, it can be seen that the inclusion of the sintering aid component of the ceramic matrix in the organometallic polymer long fiber is effective in producing a dense body.

[0050]

Example 13 As an organometallic polymer compound, a diameter of 15
A yarn obtained by bundling 500 μm long polycarbosilane long fibers was three-dimensionally woven into a cubic shape having a size of 4 × 4 × 4 cm. The porosity of the preform was 55%. Next, as a raw material of the ceramic matrix, a silicon powder having a particle diameter of 0.5 μm and an aqueous solvent of C powder (1: 1 molar ratio) of 20 nm were mixed to form a slurry, which was then poured into the voids of the preform to produce a molded body. . An acceleration voltage of 2 M
V, an electron beam was irradiated at a dose rate of 1 kGy / s until a dose of 20 MGy to infusify the polycarbosilane long fibers in the molded body. Then, at 1450 ° C in an argon atmosphere
At a heating rate of 1 ° C./min to mineralize the polycarbosilane long fibers and obtain a silicon carbide ceramic matrix. The shrinkage due to sintering was less than 3%. Thereby, silicon carbide composite ceramics (porosity of 5 vol.) Reinforced with three-dimensional woven Si-CO long fibers
%)was gotten. The ratio of long fiber / silicon carbide matrix is 75/25 vol%. At the portions where the three-dimensional weave Si-CO long fibers intersect, they were chemically bonded. The strength of the obtained composite ceramics was 412 MPa, and this strength was maintained from room temperature to 1500 ° C.

[0051]

Example 14 As an organometallic polymer compound, a diameter of 25 was used.
A yarn obtained by bundling 500 μm long polycarbosilane long fibers was three-dimensionally woven into a cubic shape having a size of 4 × 4 × 4 cm. The porosity of the preform is 35%. Next, as a raw material for the ceramic matrix, yttrium oxide (3mas
s%), aluminum oxide (3 mass%) and an aqueous solvent were mixed to form a slurry, which was poured into the voids of the preform to produce a molded body. An acceleration voltage of 5 MV is applied to this compact.
An electron beam was irradiated at a dose rate of 4 kGy / s until a dose of 20 MGy to infusify the polycarbosilane long fibers in the molded body. Then, after heating to 1300 ° C. in an argon atmosphere, the mixture was maintained at 1750 ° C. for 5 hours in a nitrogen atmosphere.
A three-dimensional woven SiC long fiber reinforced silicon nitride composite ceramics was obtained. Long fiber / silicon nitride matrix ratio is 70/3
0 vol%. The strength of the obtained composite ceramics was 680 MPa, and this strength was maintained from room temperature to 1100 ° C. This composite ceramic has a large destructive work and exhibits a destructive form that does not cause catastrophic destruction.

[0052]

According to the present invention, a preform molded article having a complicated shape can be produced by using a flexible organometallic polymer fiber, and a raw material for forming a ceramic matrix is contained in the molded article. It is possible to simultaneously form the composite and inorganicize the organometallic polymer fiber to obtain an inorganic long fiber having a radius of curvature of 0.5 mm or more and sinter the ceramic matrix. As a result, a composite ceramic having excellent low-cost, high-temperature strength, and excellent reliability such as toughness, high thermal shock resistance, and foreign matter impact resistance can be obtained. The composite ceramics thus obtained can be used under severe conditions that could not be applied conventionally. For example, corrosion resistance for rotor blade parts for gas turbines, vane parts, combustor parts, shroud parts, nuclear parts, etc.
It can be applied as a part with high wear resistance.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a structure of an example of a composite ceramic of the present invention.

FIG. 2 is a process chart showing an example of a method for producing a composite ceramic of the present invention.

FIG. 3 is a schematic view showing an example of a formed body of the composite ceramics shown in FIG. 1 before sintering.

[Explanation of symbols]

 Reference Signs List 1 ceramic matrix 2, 3 inorganic long fiber 5 particle 6 whisker 7 raw material powder for ceramic matrix 8 preform

Continuing from the front page (72) Inventor Akio Chiba 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Tsuneyuki Kanai 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor Kunihiro Maeda 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Hitachi Research Laboratory (56) References JP-A-2-275758 (JP, A) ( 58) Field surveyed (Int.Cl. ⁶ , DB name) C04B 35/80

Claims (15)

(57) [Claims] 1. A composite ceramic having a skeleton structure of inorganic long fibers in which a crossing inorganic long fibers are chemically bonded in a ceramic matrix and each inorganic long fiber has a radius of curvature of 0.5 mm or more. 2. The method according to claim 1, wherein the inorganic long fibers are silicon carbide, Si—C
-O, silicon nitride, Si-NO, Si-Ti-CO,
Si-Ti-NO, Si-Ti-NCO, aluminum nitride, Al-NO, Al-Ti-CO, Al
-Ti-NO, Al-Ti-NCO, Si-Al
-O, Si-Al-CO, Si-Al-NO, Si
-Al-N-C-O, chromium nitride, Si-Cr-C-
O, Si-Cr-NO, Si-Cr-NCO, zirconium nitride, Si-Zr-CO, Si-Zr-N
2. The composite ceramic according to claim 1, comprising at least one of -O, Si-Zr-NCO. 3. The method according to claim 2, wherein the ceramic matrix is Si,
At least one of Al, Cr, Ti, Zr, Hf, W and Y
2. The composite ceramic according to claim 1, wherein the composite ceramic contains one of a kind of nitride, carbide, oxide, oxynitride, and carbonitride. 4. One-dimensional orientation, two-dimensional orientation, three-dimensional orientation,
A step of combining a long fiber of an organometallic polymer compound composed of at least one kind of woven fabric with a raw material for forming a ceramic matrix to form a molded body, and forming the molded body with one of an electron beam and a γ ray or A step of irradiating both in an inert atmosphere to infusibilize the long fibers, and a step of heating the molded body in an inert atmosphere to densify the ceramic matrix, Manufacturing method of composite ceramics. 5. One-dimensional orientation, two-dimensional orientation, three-dimensional orientation,
A step of combining a long fiber of an organometallic polymer compound composed of at least one kind of woven fabric with a raw material for forming a ceramic matrix to form a molded body, and forming the molded body with one of an electron beam and a γ ray or A step of irradiating both the fibers with heating in an inert atmosphere to infusibilize the long fibers and at the same time densify the ceramic matrix. 6. One-dimensional orientation, two-dimensional orientation, three-dimensional orientation,
A step of combining a long fiber of an organometallic polymer compound composed of at least one kind of woven fabric with a raw material for forming a ceramic matrix to form a molded body, and forming the molded body with one of an electron beam and a γ ray or Irradiating them both in an inert atmosphere to infusibilize the long fibers, and heating the molded body in an atmosphere containing at least one of a nitriding gas, a carbonizing gas, and a silicifying gas. Depositing a ceramic matrix from a raw material to densify the ceramic matrix. 7. One-dimensional orientation, two-dimensional orientation, three-dimensional orientation,
A step of combining a long fiber of an organometallic polymer compound composed of at least one kind of woven fabric with a raw material for forming a ceramic matrix to form a molded body, and forming the molded body with one of an electron beam and a γ ray or Both are irradiated while heating in an atmosphere containing at least one of a nitriding gas, a carbonizing gas, and a silicifying gas to infusibilize the long fibers and simultaneously precipitate a ceramic matrix from the raw material to form the ceramic matrix. And a step of densifying the composite. 8. The method according to claim 4, wherein the organometallic polymer compound contains at least one of silicon, titanium, zirconium, chromium, and aluminum. . 9. The method according to claim 9, wherein the organometallic polymer is boron, beryllium, scandium, vanadium, iron, selenium, strontium, hafnium, molybdenum, tungsten, which is a sintering aid component of a ceramic matrix.
The method according to claim 8, further comprising at least one of yttrium, niobium, tantalum, and a rare earth element. 10. The long fiber obtained after the heating,
Silicon carbide, Si-CO, silicon nitride, Si-NO, S
i-Ti-CO, Si-Ti-NO, Si-Ti-
N-C-O, aluminum nitride, Al-NO, Al-
Ti-CO, Al-Ti-NO, Al-Ti-N-
CO, Si-Al-O, Si-Al-CO, Si-
Al-NO, Si-Al-NCO, chromium nitride,
Si-Cr-CO, Si-Cr-NO, Si-Cr
—N—C—O, zirconium nitride, Si—Zr—C—
The method for producing a composite ceramic according to any one of claims 4 to 7, wherein the method is at least one of O, Si-Zr-NO, and Si-Zr-NCO. 11. The method according to claim 4, wherein the ratio of the long fibers to the ceramic matrix in the composite ceramic obtained after the heating is 20:80 to 80: 20% by volume. The method for producing a composite ceramic according to claim 1. 12. The ceramic powder according to claim 1, wherein said ceramic matrix is made of at least one of Si, Al, Cr, Ti, Zr, Hf, W and Y nitrides, carbides, oxides, oxynitrides and carbonitrides. Or Si, Al, Cr, Ti,
The method for producing a composite ceramic according to any one of claims 4 to 7, comprising at least one kind of metal powder of Zr. 13. The ceramic matrix of the composite ceramic, wherein Si, Al, Cr, Ti, Zr, Hf,
The method for producing a composite ceramic according to any one of claims 4 to 7, further comprising at least one of nitrides, carbides, oxides, oxynitrides, and carbonitrides of W and Y. 14. The method according to claim 1, wherein the precipitate formed during heating is S
It is made of at least one kind of nitride, carbide, oxide, oxynitride and carbonitride of i, Al, Cr, Ti, Zr, Hf, W and Y, and has a whisker shape or a particle shape having a diameter of 5 nm to 5 μm. The method for producing a composite ceramic according to claim 6, wherein: 15. A deposit generated during the heating is formed by S
i, Al, Cr, Ti, Zr, Hf, W, and at least one of nitrides, carbides, oxides, oxynitrides, and carbonitrides, in the form of particles, within the grains and at the grain boundaries of the ceramic matrix. The method for producing a composite ceramic according to claim 6, wherein the composite ceramics are dispersed.