JP2926468B2 - Silicon carbide ceramics and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon carbide ceramic, and more particularly to a silicon carbide ceramic having excellent strength and fracture toughness, and a method for producing the same.

[0002]

BACKGROUND ART SiC has to have oxidation resistance at high temperatures, high strength properties, excellent material characteristics such as wear resistance, Si ₃ N
₄ together with the attention as an important new ceramics material for the next generation, research and development have been actively conducted. These SiC sintered bodies are expected to be applied as so-called engineering ceramics utilizing their characteristics, such as high-temperature components such as gas turbine components, wear-resistant components in nuclear power plants, and plasma facing components for fusion reactors. Have been.

In order to be used as such engineering ceramics, it must be a highly reliable material having excellent strength and toughness. One of the methods for this is to strengthen the strength by hybridizing micro-composites such as dispersed particles, whiskers, short fiber reinforcement and long fiber reinforcement with nano-composites such as intragranular composite, grain boundary composite and nano-composite.・ There is a “nano-composite ceramic” that aims to achieve the goal for toughness. Regarding this “nanocomposite ceramics”, for example, the 13th of “Metal (April 1992)”
Page 18 to page 18.

[0004]

FIG. 6 is a schematic diagram showing the structure of an Al ₂ O ₃ / SiC-based material in which SiC is dispersed in an alumina matrix as a typical material structure of the conventional “nano-composite ceramics”. Show. As shown in FIG. 6, the structure is such that the nanoparticles 5 are dispersed in the ceramic crystal 1 as a matrix. The nanoparticles 5 deflect the cracks with respect to the introduced cracks, and aim at increasing the fracture toughness due to the increase in the fracture energy. In the Al ₂ O ₃ / SiC system, the toughness is 3.
It is shown to increase from 5 to 4.8 MPa√m.
However, considering the industrialization of ceramic materials,
Such an improvement in toughness is not sufficient, and a toughness of about 10 MPaMPm is required.

An object of the present invention is to provide a silicon carbide ceramic having particularly excellent fracture toughness and a method for producing the same.

[0006]

In order to achieve the above-mentioned object, the present invention provides a method for manufacturing a semiconductor device comprising the steps of:
Crystals of the compound of the -Si-O, compounds of Zr-Si-O crystal, also
Is Ln-Si-O (Ln is at least of Y, La, Ce, Sm, Ho, Er, Yb
Silicon carbide containing crystals of ( 1) compound
In the above, the silicon carbide crystal is made of silicon carbide as a raw material.
Has crystals of silicon carbide grown around the crystal
It has a multiple structure, and the crystal of the Al-Si-O compound is
Alumina in the center of
And the crystal of the Zr-Si-O compound is
Zirconia at the core and zirconia surrounding the zirconia
Wherein the crystal of the Ln-Si-O compound is
Yes and Ln ₂ O ₃ of eccentric part, and a Ln ₂ Si ₂ O ₇ surrounding the Ln ₂ O ₃
It is characterized by doing.

In addition, the above-mentioned silicon carbide ceramics
Carbon fiber, silicon carbide fiber, silicon carbide whisker,
Silicon carbide short fiber, silicon nitride whisker, or nitriding
It is characterized by containing silicon short fibers.

[0008]

[0009] silicon carbide ceramics of the present invention can be used gas turbine blade, nuclear power plants for the wear member, a nuclear fusion reactor for the plasma-facing member.

[0010] In the method of manufacturing silicon carbide ceramics according to the present invention, a carbon powder, a silicon carbide powder, Al
Mina, zirconia, or Ln ₂ O ₃ (Ln is Y, La, Ce, Sm, H
o, unoxidized Er, a mixing step of mixing a powder containing at least one) of Yb, a shaping step of shaping the green compact of a predetermined shape by applying pressure to the mixed powder, the powder compact a heat treatment step of heat treatment in an atmosphere and presintered body, the preliminary sintering
Body and metallic silicon above the temperature at which metallic silicon melts
An impregnating step of heating to impregnate silicon into the temporary sintered body .

Furthermore, the manufacturing method of silicon carbide ceramics according to the present invention, a carbon powder, a silicon carbide powder, A
Lumina, zirconia, Ln ₂ O ₃ (Ln is Y, La, Ce, Sm, Ho, Er, Y
b) mixing the powder with carbon fiber, silicon carbide fiber, silicon carbide whisker, silicon carbide short fiber, silicon nitride whisker, or nitriding. a filling step of filling the fibrous structure containing silicon Mototan fibers, a heat treatment step of the mixed powder and heat treated presintered body in a non-oxidizing atmosphere the fiber structure filled, the preliminary sintering Body and metal silicon, metal silicon
Is heated to a temperature higher than the temperature at which
And an impregnating step of impregnating the element .

[0012]

The present inventors have conducted various studies and found that in order to enhance the fracture toughness of silicon carbide ceramics, "the silicon carbide as the matrix is made of polycrystalline material and the grain boundaries are made of Al-Si. -O compound, Zr-Si-O compound, Ln-Si-
It has been found that it is effective to include at least one oxide of a compound of O "and to" include carbon fibers and silicon carbide fibers "in order to further improve the fracture toughness. Here, Ln represents a lanthanum series element and an actinium series element and Y.

FIG. 1 shows a typical material structure of the present invention.
Reference numeral 1 denotes a matrix SiC. The SiC crystal 3 grown during the sintering process under the influence of the crystal orientation of the crystal 1 is indicated by 3. The crystals 1 and 3 have the same orientation when grown epitaxially, but the crystal orientations of 1 and 3 do not always match. The grain boundaries of this SiC matrix are Al-Si
-O, a compound of Zr-Si-O and a compound of Ln-Si-O, including at least one composite oxide 4, and a single oxide represented by 2, alumina, zirconia, Ln ₂ O ₃ Coexist.

The volume ratio of a single oxide and its composite oxide, ie, alumina / (alumina + mullite), zirconia / (zircon + zirconia), Ln ₂ O ₃ / (Ln-Si-O +
The volume ratio of Ln ₂ O ₃ ) is 10% or more and 90% or less,
Further, mullite and alumina, zircon and zirconia, the volume ratio of Ln-Si-O and Ln ₂ O ₃ occupies the entire sintered body is not more than 40% more than 2%. Below this range, the effect on toughness improvement is small, and above this range, the proportion of the compound in the grain boundary part with respect to the SiC matrix increases, and the strength characteristics inherent to SiC are exhibited to the maximum. Can not.

The most suitable method for producing the silicon carbide ceramics according to the present invention is a reaction sintering method. In the reaction sintering method, the SiC-C compact is pre-sintered at a temperature of about 700 to 900 ° C, and then heated to a temperature higher than the temperature at which silicon metal melts, and the molten silicon contacts the pre-sintered body. This is a method in which Si is impregnated by capillary action utilizing pores in the temporarily sintered body.

Hereinafter, the compound of Al-Si-O will be described in detail. Silicon carbide powder, carbon black, and alumina are mixed, a phenol resin is added as a binder, and the mixed powder is mixed by ball milling in an ethanol solvent. The mixed powder is subjected to CI at a pressure of about 1 ton / cm ^2.
After P molding, heat treatment is performed at 800 to 1700 ° C. for several hours in a vacuum of about 10 to ² Torr or in an inert gas atmosphere to obtain a temporary sintered body. The mixing and molding are not limited to the ball mill and the CIP.

Next, about twice the weight of silicon metal is placed on the pre-sintered body and placed in a vacuum of 3 to 10 to ² Torr and 1500
Heat treatment is performed at 1700 ° C. for 0.5 to several tens of hours to impregnate the metal silicon. Thus, a material in which alumina / mullite is dispersed and precipitated in the SiC matrix can be obtained.

The material thus obtained has a four-point bending strength of about 1000 MPa, and a Vickers indenter is pressed against the mirror-polished surface of the test piece. Further, cracks are generated on the diagonal extension from the four corners of the indentation, and According to the IF (Indentation Fracture) method of evaluating toughness by measuring the diagonal length, a fracture toughness value of several tens MPa · MPam is obtained.

As described above, according to the present invention, it is possible to improve the toughness incomparably with 3 to 5 MPa√m of the conventional SiC ceramics. In order to facilitate the formation, it is necessary to form a composite with a long fiber. Suitable long fibers are long fibers mainly composed of carbon fiber and silicon carbide, and the volume ratio of these long fibers in the sintered body is 60%.
% Or less. If the fiber volume ratio is higher than this, Si
This is because the heat and oxidation resistance properties of the C matrix are not sufficiently exhibited.

Here, an example of manufacturing a long fiber composite material will be described.
The fibers were arranged one-dimensionally, two-dimensionally, and three-dimensionally using a continuous fiber of silicon carbide or carbon fibers having about 500 to 3,000 fiber bundles, and shaping was performed. In the one-dimensional arrangement, one-dimensional orientation of the fibers, in the two-dimensional arrangement, plain weave, satin weave, and entanglement weave, and in the three-dimensional arrangement, orthogonal tissue weave and entanglement weave are desirable. When whiskers or short fibers are used, it is desirable to use a mat-shaped nonwoven. The fiber content Vf at this time is 60% or less. This fiber structure is filled with the above-mentioned composition powder. As a filling method, a method of making a slurry and filling is simple, but not limited to this. That is, silicon carbide powder, carbon black, and alumina are mixed, a phenol resin is added as a binder, and a mixed powder slurry is obtained by ball mill mixing in an ethanol solvent. The slurry is impregnated with the slurry by pressure impregnation. This impregnated structure is subjected to a heat treatment at 800 to 1700 ° C. for several hours in a vacuum of about 10 to ² Torr or in an inert gas atmosphere to form a temporary sintered body. Do. In this way, it is possible to obtain a silicon carbide ceramic in which alumina / mullite is dispersed and precipitated in the SiC matrix and further reinforced by long fibers and whiskers.
The four-point bending strength is about the same at about 1000 MPa, which is about the same as that without the long fiber, but the fracture toughness value is several times larger and about 70 MPa · √m can be obtained.

The silicon carbide ceramic of the present invention can be applied to a part or the whole of a rotor blade, a stationary blade for a gas turbine, a wear-resistant member for a nuclear power plant, and a plasma facing member for a fusion reactor. When whiskers or short fibers are used, it is desirable that the direction of the main fiber axis is made to coincide with the direction of the main stress applied to the material during use.

Next, a mechanism for improving toughness will be described. The mechanism of toughness improvement is as follows: i) The resistance to crack initiation is
i) It can be classified into two types, one due to resistance to continued crack growth. The former includes internal stress (residual stress generated by the second phase having a different coefficient of thermal expansion), load transfer (load is applied to the second phase having a high elastic modulus), and the latter includes a closure stress (closure stress). ), A mechanism to reduce the strain by volume expansion, a mechanism to reduce the stress concentration of the main crack by the interaction between the microcrack and the main crack in the wake of the crack, Deflection, bending, branching, etc. are affecting.

The material of the present invention has a material structure in which, among these mechanisms for improving toughness, the above-mentioned and. That is, as shown in FIG.
There is a composite oxide with silicon having a larger coefficient of thermal expansion than SiC1, which is a matrix, and the inside thereof has a smaller coefficient of thermal expansion than that of the composite oxide.
Larger oxides are present. For this reason, residual compressive stress can be generated inside the SiC matrix by a mechanism, and some of these composite oxides have a higher elastic modulus than the matrix. In some cases, the load can be shared by the mechanism.

Further, SiC as a matrix is composed of S
iC1 and SiC crystal 3 grown under its crystallographic influence
The interface of 1 and 3, the interface of 3 and 4, the interface of 2 and 4, and the interface of 4 and 4 cause crack deflection, bending and branching of the mechanism. And when these materials are compounded with long fibers, whiskers, short fibers, etc., these are responsible for the strength and toughness, and furthermore, the relaxation energy at the matrix and long fibers, whiskers, short fiber interfaces occurs, Significant improvements in strength and toughness are possible.

FIG. 6 schematically shows the structure of a conventional nanocomposite, in which nanoparticles 5 are dispersed in a matrix 1. In this structure, an oxide having a large thermal expansion is applied to the nanoparticles 5. In the case of dispersing, it is conceivable to improve the mechanism and the toughness due to the deflection of cracks at the interface between 1 and 1. However, as is apparent from a comparison between FIG. 6 and FIG. 1, the interface according to the present invention has overwhelmingly many interfaces where crack deflection, bending and branching occur. For this reason, in the silicon carbide ceramic of the present invention, the release energy of cracks is extremely large as compared with the conventional example.

[0026]

Embodiments of the present invention will be described below. (Example 1) α-type silicon carbide powder having an average particle diameter of 2 μm, carbon black having an average particle diameter of 0.01 μm, and alumina having an average particle diameter of 0.2 μm were mixed in the composition ratio of sample numbers 1 to 5 in Table 1. And a phenol resin as a binder
g and ethanol were added, and mixed with a ball mill using SiC balls to obtain a mixed powder. This mixed powder was molded at a pressure of 1000 kg / cm ² and then heat-treated at 1000 ° C. for 1 hour in a vacuum of 10 to ² Torr to obtain a calcined body. About twice the weight of metallic silicon was placed on this calcined body, and heat treatment was performed at 1600 ° C. for 1 hour in a vacuum of 10 to ² Torr to impregnate it.

Regarding the strength and fracture toughness values after the reaction sintering, a Vickers indenter was pressed against the surface of the test piece polished to a mirror surface according to JIS 4-point bending test, and cracks were formed on the diagonal extension from the four corners of the indentation. Then, the diagonal length of the indentation was measured and evaluated by the IF method. The results are shown in Table 1. As can be seen from Table 1, Sample Nos. 2 to 4 corresponding to the silicon carbide ceramics of the present invention (volume ratio of mullite and alumina in the entire sintered body was 2% In the above, the strength and the fracture toughness value were both satisfactory.

[0028]

[Table 1]

Example 2 For a sample having the composition of sample No. 3 of Example 1, powder mixing, molding,
After sintering, about twice the weight of metallic silicon is placed on the calcined body, the reaction time is set to 10 hours in a vacuum of 10 to ² Torr, and the sintering temperature is 1450 ° C. to 1800 ° C. ° C
And impregnation was performed.

The strength and fracture toughness after reaction sintering were evaluated in the same manner as in Example 1. Table 2 shows the results. As can be seen from Table 2, the sample Nos. 7 to 9 (mullite / (alumina + mullite) having a volume ratio of 10% or more corresponding to the silicon carbide ceramics of the present invention) were obtained. 90% or less), both the strength and the fracture toughness value were satisfactory.

[0031]

[Table 2]

Example 3 α-type silicon carbide powder having an average particle size of 2 μm, carbon black having an average particle size of 0.01 μm,
And ZrO ₂ having an average particle size of 0.3 μm
And 14 g of a phenol resin as a binder and 140 cc of ethanol were added thereto, and mixed with a ball mill using SiC balls to obtain a mixed powder. Then, a reaction sintered body was obtained from this mixed powder through exactly the same steps as in Example 1.

The strength and fracture toughness after reaction sintering were evaluated by the JIS four-point bending test method and the IF method. Table 3 shows the results. As can be seen from Table 3, Sample Nos. 12 and 13 (zircon and zirconia accounted for 2% by volume of the entire sintered body) corresponded to the silicon carbide ceramics of the present invention. In the above, the strength and the fracture toughness value were both satisfactory.

[0034]

[Table 3]

Example 4 A sample having the composition of sample No. 13 of Example 3 was mixed with powder, molded and pre-sintered in the same manner as in Example 1, and then the calcined body was placed on the calcined body. Double the weight of metallic silicon, set the reaction time in a vacuum of 10 to ² Torr for 10 hours, and raise the sintering temperature from 1450 ° C to 180
The impregnation was performed by changing the temperature to 0 ° C.

The strength and fracture toughness after reaction sintering were evaluated in the same manner as in Example 1. Table 4 shows the results. As can be seen from Table 4, Sample Nos. 16 and 17 corresponding to the silicon carbide ceramics of the present invention were used.
(The volume ratio of zircon / (zirconia + zircon) is 1
0% or more and 90% or less), both the strength and the fracture toughness value were satisfactory.

[0037]

[Table 4]

Example 5 α-type silicon carbide powder having an average particle size of 2 μm and carbon black having an average particle size of 0.01 μm;
And Y ₂ O ₃ having an average particle size of 0.3 μm
To 23, and 1 g of a phenol resin as a binder and 140 cc of ethanol were added thereto, and the mixture was mixed by a ball mill using SiC balls to obtain a mixed powder. A reaction sintered body was obtained from this mixed powder through exactly the same steps as in Example 1.

Regarding strength and fracture toughness after reaction sintering,
It was evaluated by the JIS four-point bending test method and the IF method. Table 5 shows the results, and as can be seen from Table 5, Sample Nos. 21 and 22 (Y ₂ Si ₂ O ₇ and Y ₂ O ₃ In the case where the volume ratio occupied in the whole is 2% or more and 40% or less), both the strength and the fracture toughness value were satisfactory.

[0040]

[Table 5]

Example 6 A sample having the composition of sample No. 22 of Example 5 was mixed with powder, molded and pre-sintered in the same manner as in Example 1, and then the calcined body was placed on the calcined body. Double the weight of metallic silicon, set the reaction time in a vacuum of 10 to ² Torr for 10 hours, and raise the sintering temperature from 1450 ° C to 180
The impregnation was performed by changing the temperature to 0 ° C.

The strength and fracture toughness after reaction sintering were evaluated in the same manner as in Example 1. Table 6 shows the results, and as can be seen from Table 6, Sample Nos. 25 and 26 corresponding to the silicon carbide ceramics of the present invention.
In the case of (Y ₂ Si ₂ O ₇ / (Y ₂ O ₃ + Y ₂ Si ₂ O ₇ ) having a volume ratio of 10% or more and 90% or less), both the strength and the fracture toughness were satisfactory. .

[0043]

[Table 6]

Example 7 α-type silicon carbide powder having an average particle size of 2 μm, carbon black having an average particle size of 0.01 μm,
And La ₂ O ₃ , Ce ₂ O ₃ , Sm ₂ O ₃ , Ho ₂ O having an average particle size of 0.1 μm
₃ , Er ₂ O ₃ , and Yb ₂ O ₃ were mixed at the composition ratios of Sample Nos. 28 to 33 in Table 7, and 1 g of a phenol resin as a binder was added thereto.
140 cc of ethanol was added and mixed with a ball mill using SiC balls to obtain a mixed powder. This mixed powder was subjected to exactly the same steps as in Example 1 to obtain a reaction sintered body.

The strength and fracture toughness after the reaction sintering were evaluated by the JIS four-point bending test method and the IF method. Table 7 shows the results. As can be seen from Table 7, sample numbers 28 to 33 (La ₂ Si ₂ O ₇ and La ₂ O ₃ , Ce ₂ Si ₃₎ corresponding to the silicon carbide ceramics of the present invention were obtained.
₂ O ₇ and Ce ₂ O ₃ , Sm ₂ Si ₂ O ₇ and Sm ₂ O ₃ , Ho ₂ Si ₂ O ₇ and Ho ₂
O ₃ , Er ₂ Si ₂ O _7, Er ₂ O ₃ , Yb ₂ Si ₂ O _7, and Yb ₂ O ₃ having a volume ratio of 2% or more and 40% or less in the whole sintered body)
Were satisfactory results in both strength and fracture toughness.

[0046]

[Table 7]

Example 8 Using a continuous fiber of silicon carbide of 500 fiber bundles, a fibrous structure composed of three types of orthogonally-woven three-dimensional fabrics having different fiber filling rates was produced. The fibrous structure was filled with a slurry using exactly the same composition powder as that of Sample No. 4 of Example 1. That is, α-type silicon carbide powder having an average particle size of 2 μm and 0.01 μm
Was mixed with alumina having an average particle size of 0.2 μm, and phenol resin was added to the mixture as a binder.
g and ethanol were added and mixed with a ball mill using SiC balls to obtain a slurry of mixed powder. The fiber structure was filled with the slurry by pressure impregnation. After the impregnated body was dried, it was subjected to a heat treatment at 1000 ° C. for 1 hour in a vacuum of 10 to ² Torr to obtain a temporary sintered body. Further, about twice the weight of metallic silicon was placed on the calcined body, and a heat treatment was performed at 1600 ° C. for 1 hour in a vacuum of 10 to ² Torr to impregnate it.

Regarding the strength and fracture toughness value after reaction sintering, a Vickers indenter was pressed against the surface of a polished test piece according to JIS four-point bending test method, and a crack was formed on the diagonal line extending from the four corners of the indentation. The diagonal length was measured and evaluated by the IF method. Table 8 shows the results.
As can be seen from Table 8, Sample Nos. 34 and 35 corresponding to the silicon carbide ceramics of the present invention (having a fiber filling ratio of 60% or less by volume in the whole sintered body)
In the results, both the strength and the fracture toughness value were satisfactory.

[0049]

[Table 8]

Example 9 A three-dimensional orthogonally woven fabric having a fiber filling rate of 41% using 500 continuous carbon fibers in a fiber bundle and a mat of 200 g / m ² using short silicon carbide fibers were used. Manufactured. These fiber structures were slurried using the same composition powder as in Example 8, and each fiber structure was impregnated by pressure impregnation. After drying these impregnated bodies, 10
Heat treatment is performed at 1000 ° C. for 1 hour in a vacuum of ~ ² Torr to form a pre-sintered body, and about twice the weight of metallic silicon is placed on the pre-sintered body, and 1600 in a vacuum of 10 ~ ² Torr 1 in ° C
Heat treatment was carried out for a time to perform reaction sintering.

The strength and fracture toughness after reaction sintering were determined by JI
S: Vickers indenter was pressed against the surface of a test piece polished to a mirror surface, and a crack was formed on the diagonal extension from the four corners of the indentation. As a result, in the structure using the continuous carbon fiber, the bending strength was 890 MPa and the fracture toughness value was 78 MPa√m, and in the silicon carbide short fiber mat structure, the bending strength was 930 MPa and the fracture toughness value was 43 MPa√m. Obtained.

Example 10 A gas turbine moving blade shown in FIG. 2 and a gas turbine stationary blade shown in FIG. 3 were produced by using a continuous fiber of 500 carbon fiber bundles of silicon carbide and a three-dimensional woven fabric having an orthogonal structure. did. As shown in FIG. 2, the gas turbine moving blade 10 includes a blade portion 11 and a platform portion 12, and as shown in FIG.
6 is provided. In this example, the fiber filling rate was 45%. Then, the fibrous structure was filled as a slurry using the same composition powder as that of Sample No. 4 of Example 1. That is, α-type silicon carbide powder having an average particle diameter of 2 μm, carbon black having an average particle diameter of 0.01 μm, and alumina having an average particle diameter of 0.2 μm were mixed, and 1 g of a phenol resin as a binder and ethanol were added thereto. 140 cc was added and mixed with a ball mill using SiC balls to obtain a slurry of mixed powder. The slurry was impregnated with the slurry by pressure impregnation. The impregnated body was subjected to a heat treatment at 1000 ° C. for 1 hour in a vacuum of 10 to ² Torr to obtain a temporary sintered body. Further, about twice the weight of metallic silicon is placed on the calcined body, and placed in a vacuum of 10 to ² Torr at 1600 ° C. for 1 hour.
Heat treatment was carried out for a time to perform reaction sintering. The soundness of the ceramic rotor blades and stator blades manufactured in this manner was confirmed under the conditions of 1500 ° C. and a rated rotation speed of 11,000 rpm.

Example 11 In the same manner as in Sample No. 3 of Example 1, a guide roller and a pin for a control drive mechanism of a nuclear power plant were manufactured. FIG. 4 shows the configuration of the guide roller and the pins. As shown in the figure, in a control drive mechanism of a nuclear power plant, a guide roller 20 is rotatably fixed to a tip of a pin fixing portion 22 by a pin 21. Since the atmosphere in which the guide roller 20 and the pin 21 are placed is at a high temperature, the guide roller 20 and the pin 21 are required to have thermal shock resistance.

When a thermal shock resistance test was actually performed, Δ
T = 250 ° C, withstand 1000 times of evaluation, and 40kgf,
It withstood 1000 shocks. In addition, the sliding distance 200
m, load applied to the indenter 50 kg / cm ² , ambient temperature 300 ° C
As a result of a sliding test in high-temperature water,
It was 2 mg / cm ² or less, and exhibited properties exceeding those of the current Stellite # 3.

(Example 12) Using 500 continuous fiber bundles and carbon continuous fibers having a thermal conductivity of 600 W / mK, the fiber filling rate was 6
A 3% one-dimensionally oriented sample was produced in exactly the same manner as in Sample No. 4 of Example 1. Irradiation at a heat flow rate of 20 MW / m ² was sound and thermal conductivity exceeded 300 W / mK.

In a nuclear fusion reactor, as shown in FIG.
A plasma facing member 27 is attached to the inner surface of the vacuum vessel 25 via a cooling substrate panel 26. The silicon carbide ceramics of the present embodiment is suitable for such a plasma facing member for a nuclear fusion reactor.

[0057]

As described above, according to the present invention, silicon carbide ceramics having excellent strength and fracture toughness can be easily obtained, and the silicon carbide ceramic can be used as a moving blade or a stationary blade for a gas turbine. Wear-resistant parts for nuclear power plants,
By applying to plasma facing members for fusion reactors, etc.
There is a great effect in industrializing so-called engineering ceramics.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a typical material structure of a silicon carbide ceramic according to the present invention.

FIG. 2 is a perspective view of a moving blade for a gas turbine.

FIG. 3 is a perspective view of a vane for a gas turbine.

FIG. 4 is a view showing a guide rod and a pin for fuel rod control drive of a nuclear power plant.

FIG. 5 is a view showing a plasma facing member for a nuclear fusion reactor.

FIG. 6 is a schematic view of a typical material structure of a conventional “nanocomposite ceramic”.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Matrix 2 Single oxide 3 Crystal grown by receiving the crystal orientation of the matrix 4 Composite oxide 5 Nanoparticle 10 Moving blade for gas turbine 11 Blade part 12 Platform part 15 Static blade for gas turbine 16 Blade part 20 Guide Roller 21 Pin 22 Pin fixing part 25 Vacuum container 26 Cooling substrate panel 27 Plasma facing member

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C04B 35/56 101K (72) Inventor Yuichi Sawai 7-1-1, Omika-cho, Hitachi City, Ibaraki Pref. Hitachi, Ltd. Hitachi Research Laboratory (72) Invention Person Kunihiro Maeda 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (56) References JP-A-61-281071 (JP, A) (58) Fields investigated (Int. Cl. ⁶⁾ , DB name) C04B 35/565

Claims (7)

(57) [Claims] (1)At the grain boundaries of the polycrystalline silicon carbide,Al
-Si-O compoundCrystal, Zr-Si-O compoundsCrystal,Also
IsLn-Si-O(Ln is at least Y, La, Ce, Sm, Ho, Er, Yb
One)Compound ofSilicon carbide ceramics containing crystals of
And The silicon carbide crystal is obtained by recovering the raw material silicon carbide crystal.
Structure with silicon carbide crystals formed by growth
And The crystal of the Al-Si-O compound is made of aluminum at the center of the crystal.
And mullite surrounding the alumina, The crystal of the Zr-Si-O compound has a zirconium
And a zircon surrounding the zirconia, The crystal of the compound of Ln-Si-O is Ln at the center of the crystal. _Two O
_Three And the Ln _Two O _Three Ln surrounding _Two Si _Two O ₇ Having That
Characterized by silicon carbide ceramics. 2. Carbon fiber, silicon carbide fiber, silicon carbide
Whisker, silicon carbide short fiber, silicon nitride whisker,
Or comprising silicon nitride short fibers.
2. The silicon carbide ceramic according to 1. 3. A blade for a gas turbine , wherein the silicon carbide ceramic according to claim 1 is used . 4. A wear-resistant member for a nuclear power plant, wherein the silicon carbide ceramic according to claim 1 is used . 5. A plasma facing member for a nuclear fusion reactor, comprising the silicon carbide ceramic according to claim 1 . 6. A carbon powder, a silicon carbide powder, and aluminum
Na, zirconia, or Ln ₂ O ₃ (Ln is Y, La, Ce, Sm, Ho, E
r, a mixing step of mixing a powder containing at least one) of Yb, a shaping step of shaping the green compact of a predetermined shape by applying pressure to the mixed powder, the green compact in a non-oxidizing atmosphere A heat treatment step of heat-treating to form a pre-sintered body, and the pre-sintered body and metal silicon are melted.
A method of impregnating the temporary sintered body with silicon by heating to a temperature equal to or higher than a temperature . 7. A carbon powder, a silicon carbide powder, and aluminum
Na, zirconia, Ln ₂ O ₃ (Ln is Y, La, Ce, Sm, Ho, Er, Yb
A powder containing at least one of the following: mixing the mixed powder with carbon fiber, silicon carbide fiber, silicon carbide whisker, silicon carbide short fiber, silicon nitride whisker, or silicon nitride. A filling step of filling the fiber structure containing short fibers , a heat treatment step of heat treating the fiber structure filled with the mixed powder in a non-oxidizing atmosphere to form a temporary sintered body, With metallic silicon, metallic silicon melts
A method of impregnating the temporary sintered body with silicon by heating to a temperature equal to or higher than a temperature .