JPH05246760A - Zirconia-based composite ceramic sintered compact and its production - Google Patents

Abstract

PURPOSE:To enhance the strength and toughness of a zirconia-based ceramic sintered compact. CONSTITUTION:This composite ceramic sintered compact is composed of partially stabilized zirconia matrix grains contg. 5-30mol% CeO2 and a dispersed phase of fine particles of one or more among Al2O3, SiC, Si3N4 and B4C or one or more of the carbides nitrides or borides of the groups IVa, Va and VIa elements of the periodic table. The fine particles have a higher m.p. than the sintering temp. of the zirconia matrix and the dispersed phase has been dispersed as a second phase in the matrix grains. When this sintered compact is produced, a powdery mixture contg. partially stabilized zirconia powder contg. 5-30mol% CeO2 and the above-mentioned fine particles having <=1mum average particle diameter is sintered at a temp. below the m.p. of the fine particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zirconia-based composite ceramic sintered body suitable for, for example, structural materials and a method for producing the same.

[0002]

2. Description of the Related Art Polycrystalline ceramic sintered bodies have excellent heat resistance, wear resistance, and corrosion resistance, so that turbocharger rotors for automobile engines, various blades, cutting tools, mechanical seals, sports leisure goods, etc. Is being used in a wide range of applications. However, ceramics are originally strong in covalent bond and ionic bond and do not show transition or plastic deformation like metal materials, so stress concentration at the tip of crack cannot be relaxed, and minute defects and surface scratches in the material cannot be relaxed. Fractures easily starting from. Since ceramic has low toughness and is extremely brittle in this way, it is not suitable as a constituent material for large parts or parts having a complicated shape, and the shape and size of the molded product are naturally limited.

Therefore, in order to improve the brittleness of the ceramic, it has been attempted to improve the toughness and strength by dispersing particles, whiskers and the like in the matrix of the ceramic sintered body so as to prevent the progress of cracks. Has been done. Ceramic compounding, which has been sought as an effective means for improving the toughness, is performed from particle dispersion to whisker dispersion and fiber reinforcement, and from microcomposite that combines grain boundaries of polycrystalline ceramics to It is shifting to composite nanocomposites. Among them, it has been reported that the nanocomposite material in which the crystal grains themselves, which are the minimum structural units of ceramics, are compounded has a remarkable effect in increasing the strength and improving the strength in the high temperature region.

For example, in a system using an oxide ceramic as a matrix, in JP-A-64-87552, an alumina sintered body obtained by compounding the inside of α-alumina matrix with SiC fine particles has high strength and high temperature range. Is said to be effective in improving the strength of. In addition to this, it is known that Al ₂ O ₃ / Si ₃ N ₄ and MgO / SiC nanocomposite materials exhibit high strength by the same method. Furthermore, one example of a system using a non-oxide ceramic as a matrix is "Powder and powder metallurgy, Vol.36, p236-p243.
(1989) ”, [Si (CH) ₃ ] ₂ NH was added to amorphous Si- by CVD method in an atmosphere of ammonia and hydrogen.
It was reported that a C—N composite powder was obtained, and a Si ₃ N ₄ / SiC nanocomposite material in which SiC particles were dispersed in Si ₃ N ₄ matrix particles using this composite powder as a starting material had high strength. Has been done.

Among these composite ceramic sintered bodies, the microcomposite material has a fracture toughness value of about 10 MPam ^1/2 in a system composed of ZrO ₂ particles and whiskers, and also has a long fracture length such as SiC. Fiber-composite systems achieve high fracture toughness values up to 20-30 MPam ^1/2 . However, the strength is only about 50 to 60% that of the polycrystalline ceramic matrix alone, and further improvement in strength is desired.

On the other hand, in the nanocomposite material, although the improvement in strength is recognized in the high temperature range, the improvement in toughness is improved by about 30 to 40% of the polycrystalline ceramic matrix.
No significant contribution to the improvement of toughness as in the microcomposite material is recognized.

As described above, further improvement in strength and toughness is expected in the polycrystalline ceramic composite material, and the strength and toughness are also improved in the partially stabilized zirconia sintered body to which CeO ₂ is added as a stabilizer. There is a demand for sintered bodies.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a zirconia-based composite ceramic sintered body having high strength and high toughness and a method for producing the same.

[0009]

The invention relating to a zirconia-based composite ceramic sintered body is 5 to 30 mol% of CeO _2.
Second, in the partially stabilized zirconia matrix particles containing
The phase has a melting point higher than the sintering temperature of the zirconia matrix, and is Al ₂ O ₃ , SiC, Si ₃ N
₄ or B ₄ C or having a dispersed phase of fine particles of at least one selected from carbides, nitrides and borides of elements belonging to IVa, Va and VIa groups of the periodic table The invention relating to the method for producing the zirconia-based composite ceramic sintered body is CeO.
Partially stabilized zirconia powder containing 5 to 30 mol% of ₂ ,
An average of at least one selected from Al ₂ O ₃ , SiC, Si ₃ N ₄ or B ₄ C or carbides, nitrides or borides of elements belonging to groups IVa, Va and VIa of the periodic table. It is characterized in that a mixed powder containing fine particles having a particle diameter of 1 μm or less is sintered at a temperature lower than the melting point of the fine particles having an average particle diameter of 1 μm or less.

The present invention will be described in detail below. It is important that the partially stabilized zirconia constituting the ceramic matrix in the present invention contains 5 to 30 mol% of CeO ₂ . Within this range, zirconia is mainly tetragonal, or a mixed phase of tetragonal and cubic,
CeO ₂ is preferably 5 mol% because high strength can be obtained.
When the amount is less than the above, tetragonal crystallization which is a metastable phase becomes insufficient, and when it exceeds 30 mol%, the amount of cubic crystals increases, and as a result, sufficient strength cannot be obtained, which is not preferable.

Further, as a method for obtaining a powder of partially stabilized zirconia using CeO ₂ as a stabilizer, a method of mixing a stabilizer and a powder of zirconia, a wet synthesis using an aqueous solution containing Ce and Zr. There is a method of obtaining powder by the method. The partially stabilized zirconia powder of the present invention is pressure-sintered,
In order to be densified by pressure sintering or the like and most of the dispersed phase be incorporated in the particles of the matrix during the sintering process, the particles must grow during the sintering. On the other hand, since the fine particles dispersed in this matrix are dispersed as fine particles after sintering, they are limited to fine particles having a melting point higher than the sintering temperature of the matrix. Then, the present inventors have found that there are various metals as the fine particles having such a high melting point, and therefore, the 1991 patent application No. 23544.
The patent application was already filed as No. 6, but in addition to the fine particles of metal, Al ₂ O ₃ , SiC, Si ₃ N ₄ or B ₄
It has been found that fine particles of at least one selected from the group consisting of carbides, nitrides or borides of C or elements belonging to groups IVa, Va and VIa of the periodic table have the same effect as the fine particles of the metal. It is an invention.

The fine particles must be fine in order to be incorporated into the matrix particles during the sintering process, and the average particle size is preferably 1 μm or less. It is desirable that all of them are dispersed inside, but it may be partly at the grain boundaries of the matrix. The amount of the dispersed phase of the above-mentioned fine particles added to the partially stabilized zirconia constituting the ceramic matrix in the present invention is 0.5 to the total amount after addition.
50% by volume is desirable, more preferably 2.5-30
Volume%. That is, when the dispersed phase is 2.5% by volume or less, the effect of improving the strength is small, and when the dispersed phase is 30% by volume or more, the densification becomes gradually difficult and the strength gradually decreases. Further, if it exceeds 50% by volume, the relative density of the composite sintered body becomes 95% or less, and it becomes difficult to obtain a dense sintered body, and as a result, the strength is remarkably deteriorated.

When the combination of the matrix and the disperse phase is referred to in terms of the coefficient of thermal expansion, if the disperse phase having a smaller coefficient of thermal expansion than the matrix is dispersed, it contributes effectively to further improving the toughness of the matrix. This is preferable, but the present invention is not necessarily limited to this. The partially stabilized zirconia using CeO ₂ as a matrix stabilizer of the present invention usually has a large coefficient of thermal expansion, and the dispersed phase shown above also satisfies the point that it has a coefficient of thermal expansion smaller than that of the matrix. ..

Next, the mechanism of the effect of improving the toughness of the zirconia-based composite ceramic sintered body according to the present invention will be considered.

The fine particles dispersed in the grains of CeO ₂ type partially stabilized zirconia ceramic constituting the matrix or partially in the grain boundaries have the effect of suppressing abnormal growth of the ceramic grains during the sintering process. However, as a result, the matrix is composed of a fine structure, which reduces the size of the fracture source and significantly increases the strength. In addition, due to the fine particles dispersed in the ceramic matrix, the tip of the crack is curved (bowing) or deflected (deflection) in the course of crack development, thereby improving the toughness of the sintered body.

Further, CeO ₂ which constitutes the matrix
In a system in which fine particles dispersed in the grains of the partially stabilized zirconia ceramic or in some grain boundaries have a smaller thermal expansion coefficient than the ceramic constituting the matrix, the dispersed fine particles are more effective in improving strength and toughness. To work. If the coefficient of thermal expansion of the ceramic and that of the fine particles do not match, a residual stress field is formed in the matrix and around the fine particles during the cooling process after sintering, and this residual stress field affects the crack propagation path. give. That is, when the thermal expansion coefficient of the fine particles is smaller than that of the ceramic, tensile stress is generated around the fine particles in the cooling process after sintering, and a residual tensile stress field is formed around the fine particles, so cracks are generated in the fine particles. It develops to be attracted, which induces intragranular fracture of the ceramic. in this way,
Since the probability that the crack will collide with the fine particles will increase, the progress of the crack will be effectively prevented. At the same time, a residual compressive stress is generated in the axial direction of the fine particles dispersed in the matrix during the cooling process after sintering, and the crystal grains themselves of the ceramic are greatly strengthened by this, further improving the strength. It will be achieved.

As a manufacturing method for obtaining the above-mentioned zirconia-based composite ceramic sintered body according to the present invention, 5% of CeO ₂ is used.
Partially stabilized zirconia powder containing ~ 30 mol% and Al ₂
An average particle diameter of at least one selected from O ₃ , SiC, Si ₃ N ₄ or B ₄ C or carbides, nitrides or borides of elements belonging to the IVa, Va and VIa groups of the periodic table. Is characterized in that the mixed powder containing fine particles having a particle size of 1 μm or less is sintered at a temperature lower than the melting point of the particles having an average particle size of 1 μm or less. And this mixed powder is CeO which is a raw material powder.
It is obtained by a method in which a predetermined amount of ₂ type partially stabilized zirconia powder and fine particles having a mean particle size of 1 μm or less, which is a dispersed phase, are mixed in a wet ball mill using ethanol, acetone, toluene or the like as a solvent, and then dried.

In the present invention, the above-mentioned mixed powder is molded into a desired shape by a dry molding method or an injection molding method, which are commonly used molding methods, and further, normal pressure sintering, vacuum sintering, gas pressure sintering, hot molding. Press sintering or hot isostatic pressing (HI
P) or the like is sintered to obtain a densified sintered body. The molding and sintering may be performed separately or simultaneously, and there is no limitation.

Further, the sintering atmosphere is such that the partially stabilized zirconia raw material powder and Al ₂ O ₃ , SiC, Si ₃ N _{4 are used.}
In order to prevent the oxidation of B ₄ C and B ₄ C and carbides, nitrides and borides of elements belonging to groups IVa, Va and VIa of the periodic table, vacuum, an inert gas atmosphere such as nitrogen gas and argon gas is suitable. Further, in hot isostatic pressing, a pre-sintered body with few open pores is prepared beforehand by normal pressure sintering, hot pressing, etc., and hot isostatic pressing is performed on the pre-sintered body or the formed body is made of metal. Any of the methods of encapsulating by air-tightly sealing with glass or glass and subjecting this to hot isostatic pressing can be applied.

In the method for producing a zirconia-based composite ceramic sintered body, a molded body obtained by using the above-mentioned mixed powder is
Embedding in monoclinic zirconia powder for sintering is preferable because a denser sintered body can be obtained.
The method for obtaining the molded body in this case is not particularly limited, and it may be molded into a desired shape by a dry press, an injection molding method, or the like. Then, for the sintering in this case, in a state in which the obtained molded body is embedded in the monoclinic zirconia powder, inserted into a container that withstands the sintering conditions, then,
Sintering may be performed under a constant volume or a slight pressure condition. Monoclinic zirconia powder is about 1170 ℃
As described above, tetragonal zirconia powder which is a high temperature stable phase is obtained in the temperature range of 2370 ° C. or lower, and crystallized into monoclinic zirconia in the temperature range of about 1170 ° C. or lower, and exhibits a volume expansion of about 4% during this crystal transformation. It has the property. Therefore, if the sintering performed in the state where the compact is embedded in the monoclinic zirconia powder is performed at the crystal transformation temperature or higher, it means that the pseudo hot isostatic pressing (pseudo HIP sintering) is performed. The effect similar to that of hot isostatic pressing is achieved, and a denser sintered body can be obtained. further,
Conventionally, CeO ₂ which is a stabilizer is easily reduced to Ce ₂ O _{3 in} a reducing atmosphere such as a carbon atmosphere,
Therefore, when sintered in a reducing atmosphere, there are problems that the crystal phase after sintering is less likely to be tetragonal and that the sintered body is cracked. Therefore, sintering in a reducing atmosphere such as a carbon atmosphere occurs. generally it was difficult, when such sintered embed the shaped body to monoclinic zirconia powder, it is possible to cut off the carbon source and the sintered body such as a carbon heater during sintering of CeO ₂ There is also an effect that the reduction can be suppressed and the problems associated with the conventional reduction of CeO ₂ can be improved.

In the case of the alumina particle dispersion type composite ceramic sintered body, it is preferable to use γ-Al ₂ O ₃ powder as a raw material for the alumina particles as the dispersion species because the primary particle diameter is very small. On the other hand, since it has a large specific surface area and is bulky, there is a problem that it is difficult to give a desired shape by a usual molding method (dry pressing method, injection molding method, etc.). Therefore, such γ−
When a manufacturing method using Al ₂ O ₃ powder was examined, a mixed powder containing partially stabilized zirconia powder containing 5 to 30 mol% of CeO ₂ and γ-Al ₂ O ₃ powder was prepared.
If the calcined powder obtained by crushing after calcination at a temperature of 1000 ° C. or higher and the sintering temperature or lower is sintered, it is possible to give a desired shape by a conventional molding method, and it is possible to obtain a compact shape. It has been found that an excellent sintered body can be obtained. In this case, the calcination temperature is preferably γ-α transition temperature (about 1000 ° C.) or higher, and 1300 ° C. or lower from the viewpoint of facilitating pulverization after calcination.

[0022]

【Example】

Examples 1 to 6 and Comparative Examples 1 to ₂ Partially stabilized zirconia powder containing CeO ₂ in an amount of 5 to 35 mol% as shown in Table 1 was used, and β-SiC having an average particle size of 0.2 μm and a purity of 98% or more was used.
5% by volume of the fine particles of 1. was mixed in a wet ball mill for 24 hours using acetone as a solvent and a polyethylene-coated iron ball and a polyethylene container. The obtained powder was formed into a disk-shaped compact having a diameter of 60 mm and a thickness of 5 mm by isostatic pressing, and the sintering temperature was 1600 ° C. in an argon atmosphere.
Sintering was performed under the condition of holding time of 2 hours.

These sintered bodies are dense with a relative density of 99% or more and a porosity of 1% or less.
Also, it was confirmed by observation with a transmission electron microscope that the SiC fine particles were present in the partially stabilized zirconia grains.

Then, the disc-shaped sintered body is cut,
Grinding is performed to prepare a sample of 4 × 3 × 35 mm, and this sample is subjected to 3 at room temperature according to JISR1601.
The point bending strength was measured. Further, the surface of the sample was mirror-polished and the fracture toughness value was measured by the SEPB method according to JIS R1607. Table 1 shows the above measurement results.

Crystal phases were identified in the above sample by X-ray diffraction, and then the proportion of each phase was quantified. The results are shown in Table 1.
Is shown as a crystal phase of zirconia. However, regarding the symbol of the crystal phase of zirconia, T is tetragonal, C is cubic, and M is
Represents monoclinic crystals, respectively.

[0026]

[Table 1]

(Examples 7 to 19) 12 mol% CeO ₂
As shown in Tables 2 and 3, the partially stabilized zirconia powder containing 5% by volume of various fine particles having an average particle size of 1 μm or less was added.
The added product was mixed in a wet ball mill for 24 hours using acetone as a solvent, using a polyethylene-coated iron ball and a polyethylene container. However, in Table 3, two types of fine particles have 2.5% by volume of each type, and the total amount is 5% by volume.
It was adjusted so that The obtained powder was molded in a high purity alumina mold in an argon atmosphere at a sintering temperature shown in Tables 2 and 3 for a holding time of 2 hours and a pressing pressure of 30MP.
Sintering was carried out under the condition of a to obtain a disk-shaped compact having a diameter of 50 mm and a thickness of 4 mm.

These sintered bodies are dense with a relative density of 99% or more and a porosity of 1% or less.
And Tables 2 and 3 by observation with a transmission electron microscope.
It was confirmed that the various fine particles shown in (3) are present in the partially stabilized zirconia grains. The crystal phase of zirconia was all tetragonal.

Then, the disc-shaped sintered body is cut,
Grinding was performed to prepare a sample of 4 × 3 × 35 mm, and the 3-point bending strength at room temperature was measured according to JISR1601 for this sample. The surface of the sample was mirror-polished and the fracture toughness value was measured by the SEPB method according to JIS R1607. The above measurement results are shown in Tables 2 and 3.

[0030]

[Table 2]

[0031]

[Table 3]

Comparative Examples 3 to 15 12 mol% CeO ₂
As the fine particles to be added to the partially stabilized zirconia powder containing, as shown in Table 4 and Table 5, disk-shaped compacts were obtained in the same manner as in Examples 7 to 19 except that various fine particles having an average particle size of more than 1 μm were used. It was

Then, the disc-shaped sintered body is cut,
Grinding was performed to prepare a sample of 4 × 3 × 35 mm, and the 3-point bending strength at room temperature was measured according to JISR1601 for this sample. The surface of the sample was mirror-polished and the fracture toughness value was measured by the SEPB method according to JIS R1607. The above measurement results are shown in Tables 4 and 5.

[0034]

[Table 4]

[0035]

[Table 5]

(Examples 20 to 25 and Comparative Examples 16 to 1)
7) β-Si having an average particle size of 0.2 μm and a purity of 98% or more is added to partially stabilized zirconia powder containing 12 mol% CeO _2.
The fine particles of C added as shown in Table 6 in an amount of 0 to 60% by volume were mixed in a wet ball mill for 24 hours using a polyethylene-coated iron ball and a polyethylene container and acetone as a solvent. The obtained powder is sintered using a high-purity alumina mold in an argon atmosphere under the conditions of a sintering temperature of 1600 ° C., a holding time of 2 hours, and a pressing pressure of 30 MPa,
A disk-shaped sintered body with a diameter of 50 mm and a thickness of 4 mm was obtained.

Among these sintered bodies, the addition amount of SiC was 5
Those with 0% by volume or less have a relative density of 99% or more and a porosity of 1
%, And it was confirmed by observation with a scanning electron microscope and a transmission electron microscope that SiC fine particles were present in the partially stabilized zirconia grains. However, if the amount of SiC added exceeds 30% by volume, densification tends to gradually become difficult as the amount added increases,
At 60% by volume, the relative density was 95% or less.

Then, the disc-shaped sintered body was cut,
Grinding was performed to prepare a sample of 4 × 3 × 35 mm, and the 3-point bending strength at room temperature was measured according to JISR1601 for this sample. The surface of the sample was mirror-polished and the fracture toughness value was measured by the SEPB method according to JIS R1607. Table 6 shows the above measurement results.

Using the values shown in Table 6, the change in the three-point bending strength at room temperature with the change in the amount of SiC added is shown in FIG.
2 shows changes in the fracture toughness value with changes in the amount of SiC added, respectively. When the content of SiC (volume%) in the sintered body was examined, the content of SiC (volume%)
And the added amount of SiC (% by volume) were in good agreement. 1 and 2, the amount of SiC added (content) is 30% by volume.
Up to 3 points bending strength,
Both the fracture toughness values were improved, and at 30 to 50% by volume, the three-point bending strength and the fracture toughness values gradually decreased with the increase of the added amount (content). And the added amount (content) is 6
The three-point bending strength and fracture toughness value at 0% by volume were lower than the three-point bending strength and fracture toughness value of the partially stabilized zirconia alone.

[0040]

[Table 6]

(Examples 26-34) Partially stabilized zirconia powder containing 12 mol% of CeO ₂ was added with 5% by volume of various fine particles having an average particle size of 1 μm or less as shown in Table 7, and was made of polyethylene-coated iron. Wet ball mill mixing was performed for 24 hours using acetone as a solvent using a ball and a polyethylene container. Φ60 of the obtained powder is obtained by isostatic pressing.
A disk-shaped molded body having a thickness of 5 mm and a thickness of 5 mm was obtained. The obtained molded body was embedded in a high-purity alumina mold having an inner diameter of 65 mm together with a monoclinic zirconia powder having an average particle diameter of 2 μm, and the sintering temperature shown in Table 7 was used in an argon atmosphere, and the holding time was 3 hours. Sintered under. In order to keep the container inside the alumina container (alumina mold) during sintering constant, sintering was performed under a condition where a slight load (about 0.1 MPa) was applied to the upper punch, and after cooling, monoclinic zirconia was used. The sintered body was taken out of the powder.

The sintered bodies obtained in Examples 26 to 34 were dense ones having a relative density of 99% or more and a porosity of 1% or less, and were observed by a scanning electron microscope and a transmission electron microscope. It was confirmed that various fine particles shown in 7 exist in the partially stabilized zirconia particles. The crystal phase of zirconia in the obtained sintered body was all tetragonal.

Then, the disc-shaped sintered body was cut,
Grinding was performed to prepare a sample of 4 × 3 × 35 mm, and the 3-point bending strength at room temperature was measured according to JISR1601 for this sample. The surface of the sample was mirror-polished and the fracture toughness value was measured by the SEPB method according to JIS R1607. Table 7 shows the above measurement results.

[0044]

[Table 7]

Example 35 A partially stabilized zirconia powder containing 12 mol% of CeO ₂ was added to a specific surface area of 300 g / m ^2.
5% by volume of the γ-Al ₂ O ₃ powder (fine particles) was mixed in a wet ball mill for 24 hours with acetone as a solvent using a polyethylene-coated iron ball and a polyethylene container. The obtained mixed powder was heated at 1200 ° C. in air for 3
After calcination for a period of time, dry pulverization was performed for 24 hours using a zirconia ball and a zirconia container. Using the calcined powder thus obtained, a hydrostatic pressure press was used to obtain a diameter of 60 mm and a thickness of 5
A disc-shaped molded body of mm was obtained. The obtained molded body was sintered in the atmosphere under the conditions of a sintering temperature of 1550 ° C. and a holding time of 3 hours. The obtained sintered body was a dense one having a relative density of 99% or more and a porosity of 1% or less, and by observation with a scanning electron microscope and a transmission electron microscope, Al ₂ O ₃ fine particles were partially stabilized zirconia. It was confirmed that they were present in the grains. The crystal phase of zirconia in the obtained sintered body was all tetragonal.

Then, the disc-shaped sintered body was cut,
Grinding was performed to prepare a sample of 4 × 3 × 35 mm, and the 3-point bending strength at room temperature was measured according to JISR1601 for this sample. The surface of the sample was mirror-polished and the fracture toughness value was measured by the SEPB method according to JIS R1607. Table 8 shows the above measurement results.

(Comparative Example 18) In Comparative Example 18, a sintered body was obtained in the same manner as in Example 35, except that the calcining treatment in Example 35 was not performed and sintering was immediately performed. ..

Γ-Al ₂ O having a specific surface area of 300 g / m ^{2 was} added to partially stabilized zirconia powder containing 12 mol% CeO _2.
Three powders (fine particles) added in an amount of 5% by volume were mixed in a wet ball mill for 24 hours using acetone as a solvent and a polyethylene-coated iron ball and a polyethylene container. The obtained mixed powder was immediately molded by a hydrostatic press without performing a calcination treatment to obtain a disk-shaped molded body having a diameter of 60 mm and a thickness of 5 mm. The obtained molded body is sintered in air at a sintering temperature of 15
Sintering was performed under the conditions of 50 ° C. and a holding time of 3 hours. The obtained sintered body had a relative density of 97% or less and was insufficiently densified.

By cutting and grinding the obtained sintered body,
A sample of 4 × 3 × 35 mm was prepared, and J
Three-point bending strength at room temperature was measured by ISR1601. In addition, the surface of the sample is mirror-polished to JIS R1
The fracture toughness value was measured by the SEPB method according to 607.
Table 8 shows the above measurement results.

[0050]

[Table 8]

[0051]

As described above, in the zirconia-based composite ceramic sintered body according to the present invention, fine particles having a melting point higher than the sintering temperature of the matrix are dispersed in the partially stabilized zirconia matrix particles that have been sintered. Since it has been
Strength and toughness are improved.

Then, partially stabilized zirconia powder containing 5 to 30 mol% of CeO ₂ and Al ₂ O ₃ , SiC, Si
₃ N ₄ or B ₄ C or IVa, Va, VIa of the periodic table
Average particle size 1 consisting of at least one selected from carbides, nitrides or borides of elements belonging to the group
A zirconia-based composite ceramic sintered body having excellent performance can be produced by a method for producing a zirconia-based composite ceramic sintered body in which a mixed powder containing fine particles having a size of μm or less is sintered at a temperature lower than the melting point of the fine particles. it can.

[Brief description of drawings]

FIG. 1 is an example of the present invention 20-25 and comparative examples 16-1.
9 is a graph showing the relationship between the amount of SiC added and the three-point bending strength at room temperature for the composite ceramic sintered body according to No. 7.

[Fig. 2] Examples 20 to 25 of the present invention and Comparative examples 16 to 1
7 is a graph showing the relationship between the amount of SiC added and the fracture toughness value for the composite ceramic sintered body according to No. 7.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichi Niihara 9-7 Korikaoka, Hirakata-shi, Osaka 1142 Kori Camp, 1142 (72) Inventor Atsushi Nakahira 1-2-2 Aoyamadai, Suita, Osaka C33- No. 307 (72) Inventor Toru Sekeno 2-3-3341, Nishimidoka, Toyonaka City, Osaka Prefecture

Claims (6)

[Claims] 1. A partially stabilized zirconia matrix particle containing 5 to 30 mol% of CeO ₂ has a second phase having a melting point higher than the sintering temperature of the zirconia matrix, and Al ₂ O ₃ , SiC, Si ₃ N ₄ or B
₄ C or the Periodic Table of the IVa, Va, carbides of elements belonging to Group VIa, zirconia composite ceramic and having a nitride compound or boron dispersed phase of fine particles at least consisting of one or more selected from among fluoride Sintered body. 2. The zirconia-based composite ceramic sintered body according to claim 1, wherein the crystal phase of zirconia in the composite ceramic sintered body is mainly tetragonal or tetragonal and cubic. 3. The zirconia-based composite ceramic sintered body according to claim 2, wherein the content of the dispersed phase is 0.5 to 50% by volume. 4. A partially stabilized zirconia powder containing 5 to 30 mol% of CeO ₂ , and Al ₂ O ₃ , SiC, Si ₃ N ₄
Or B ₄ C or at least one selected from carbides, nitrides and borides of elements belonging to the IVa, Va and VIa groups of the Periodic Table, having an average particle size of 1 μm
A method for producing a zirconia-based composite ceramic sintered body, which comprises sintering a mixed powder containing the following fine particles at a temperature lower than the melting point of the fine particles having an average particle diameter of 1 μm or less. 5. The method for producing a zirconia-based composite ceramic sintered body according to claim 4, wherein the molded body obtained by using the mixed powder is embedded in monoclinic zirconia powder and sintered. 6. The partially stabilized zirconia powder, wherein the mixed powder contains 5 to 30 mol% of CeO ₂ , and γ-Al ₂ O ₃
And a mixed powder containing powder, and the mixed powder is
The calcined powder obtained by pulverizing after calcination at a temperature of 0 ° C. or higher and a sintering temperature or lower is sintered.
Alternatively, the method for producing the zirconia-based composite ceramic sintered body according to item 5.