JP2002121070A - Sintered low temperature thermal deterioration resistant zirconia compact and method of manufacturing for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sintered zirconia compact having excellent mechanical strengths and thermal stability in combination. SOLUTION: The sintered low temperature thermal deterioration resistant zirconia compact is the sintered zirconia compact essentially consisting of ZrO2 and containing at least one kin of stabilizers Y2O3 and Sc2O3 and is characterized in that (1) the molar ratio of the stabilizers and the ZrO2 is 1.5:98.5 to 4:96, (2) the sintered compact contains at least one kind of rare earth aluminate consisting of LaAlO3, PrAlO3 and NdAlO3 and (3) the sintered compact consists of a mixed phase of at least one kind of a monoclinic crystal and a cubic crystal or a tetragonal single phase and the method of manufacturing for the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel zirconia sintered body and a method for producing the same.

[0002]

_2. Description of the Related Art In recent years, sintered zirconia (ZrO ₂ ) materials have various properties such as excellent strength, toughness, heat resistance and the like, and are widely used for applications corresponding to the respective properties. For example, ceramic scissors, medical materials, etc. that apply their high strength, high toughness, etc .; mold extrusion dies, etc., utilizing lubricity; for heat-insulating engines, which use the properties of heat insulation, thermal expansion, etc. Parts and the like; oxygen sensors, fuel cells, and the like utilizing oxygen ion conductivity have been put to practical use.

In particular, a zirconia sintered body to which Y ₂ O ₃ , Sc ₂ O ₃ or the like is added as a stabilizer has excellent mechanical properties as compared with other ceramics, and a product utilizing this property. Is also being actively developed. In recent years, it has also attracted attention as a pulverizing medium (media) used for mixing or pulverizing ceramic materials, metal powders, food products, and the like. In addition, this zirconia sintered body has a very small crystal grain size and a uniform microstructure, and it is easy to obtain a precisely polished surface. Therefore, an optical fiber requiring high dimensional accuracy of several μm or less is required. Applications as a connector ferrule material are also expanding rapidly. Further, the zirconia sintered body is excellent in oxygen ion conductivity, and it is expected that its use as a fuel cell material and the like will be further increased in the future.

[0004] Incidentally, the fracture strength of a zirconia sintered body using Y ₂ O ₃ , Sc ₂ O ₃ or the like as a stabilizing agent exhibits particularly excellent performance when its content is 4 mol% or less. Are known. On the other hand, this zirconia sintered body has a disadvantage that the strength is likely to deteriorate due to long-term aging in a low temperature region. The reason for this is that, at room temperature, the tetragonal phase, which is a metastable phase, undergoes a phase transition to the monoclinic phase, which is a stable phase, at room temperature, and the volume expansion accompanying this phase transition causes microcracks in the sintered body. In order to generate it.
This problem is particularly noticeable when aging in water at 100 to 300 ° C. or in steam. For this reason, even if the zirconia sintered body has a high strength, its use is limited due to poor thermal stability in a low temperature region.

As this type of zirconia sintered body, for example, a zirconia porcelain excellent in mechanical properties and oxide ion conductivity and a method for producing the same (Japanese Patent Publication No. 2-58232) are known. However, when this zirconia porcelain is left at around 100 to 300 ° C. for a long period of time, its strength is significantly deteriorated. In particular, the rate of deterioration is extremely high in an environment in water or in water vapor, so that it is difficult to use in such an environment.

[0006] A pulverizing member made of a zirconia sintered body of this type significantly deteriorates in strength when left at about 100 to 300 ° C for a long time. In particular,
In the environment of water or steam, the rate of strength deterioration is also very fast, so when using water as a solvent, for example, when using in a wet pulverization process, or after washing a pulverizing member with water or the like When drying is performed at a high temperature (around 200 ° C.), the strength is significantly deteriorated. Further, since an optical fiber connector ferrule material made of a zirconia sintered body of this kind can be used in any temperature and humidity environment, having a low-temperature thermal degradation phenomenon can be a fatal defect.

[0007]

On the other hand, in order to improve the thermal stability, boron compounds (for example, B ₂ O ₃ )
And Al ₂ O ₃ and / or zirconia sintered body containing a SiO ₂ has been proposed (JP-A-6-239662, etc.).

However, in this sintered body, since the additive is present as a glass component, not only the elastic modulus and strength are reduced at 600 ° C. or more, but also when the sintered body is used as a pulverizing part, the wear resistance is reduced. Problems such as a decrease in

On the other hand, a stabilizer mainly composed of Y ₂ O ₃ is used.
5-5 60-99 wt% of ZrO ₂ containing mol% mullite Al ₆ Si ₂ O ₁₃ or pyrochlore La ₂ Zr ₂ O ₇ 1
A zirconia-based sintered body comprising up to 40% by weight is known (JP-A-61-26562). In addition, Dy ₂
A zirconia sintered body is known in which O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Yb ₂ O ₃ or the like is used as a main stabilizer and an oxide such as La, Pr or Nd is added as a property improver. (Japanese Unexamined Patent Publication No.
No. 329468).

[0010] However, in the case of the zirconia sintered body disclosed in JP-A-61-26562, although the thermal stability can be improved by the presence of the pyrochlore phase, the absolute mechanical strength is low. In JP-A-6-329468, the mechanical strength at room temperature is somewhat improved, but the thermal stability is still insufficient, and there is room for further improvement in this respect.

Accordingly, a main object of the present invention is to provide a zirconia sintered body having both excellent mechanical strength and thermal stability.

[0012]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the problems of the prior art, and as a result, have found that a zirconia sintered body having a specific composition can achieve the above object, and completed the present invention. I came to.

That is, the present invention relates to the following zirconia sintered body having low temperature resistance to heat degradation and a method for producing the same.

1. ZrO ₂ as the main component, Y ₂ O ₃ and S
A zirconia sintered body containing at least one stabilizer of c ₂ O ₃ , wherein (1) the molar ratio of the stabilizer to ZrO ₂ is 1.5: 98.5 to 4:96, (2) LaAlO
₃ , containing at least one rare earth aluminate composed of PrAlO ₃ and NdAlO ₃ , and (3) a mixed phase of at least one of monoclinic crystals and cubic crystals and a tetragonal crystal or a tetragonal single phase. A zirconia sintered body that is resistant to low-temperature heat degradation.

2. 2. The method for producing a low-temperature thermally degradable zirconia sintered body according to the above item 1, wherein (1) at least one of an yttrium compound and a scandium compound,
Preparing a raw material mixture containing at least one rare earth aluminate composed of LaAlO ₃ , PrAlO ₃ and NdAlO ₃ and a zirconium compound; (2) calcining the raw material mixture at 500 to 1200 ° C.
(3) a step of pulverizing and molding the calcined body, and (4)
A manufacturing method, comprising a step of sintering the molded body at 1300 to 1650 ° C.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION1. Low temperature heat-resistant zirconia
Sintered body The low-temperature heat-degradable zirconia sintered body of the present invention is made of ZrO.
_Two, And Y_TwoO _ThreeAnd Sc_TwoO_ThreeAt least one of
Zirconia sintered body containing a stabilizer of (1)
Stabilizer and ZrO_TwoIs 1.5: 98.5 to 4:
96 and (2) LaAlO_Three, PrAlO_ThreeAnd Nd
AlO_ThreeAt least one rare earth aluminate consisting of
And (3) at least one of a monoclinic crystal and a cubic crystal.
It consists of a mixed phase with tetragonal or a single phase of tetragonal
And

Y ₂ O ₃ and / or Sc ₂ as stabilizers
The content of O ₃ is usually about 1.5 to 4 mol%,
Preferably it is 2-3 mol%. If the Y ₂ O ₃ content is too small, the desired effect of adding Y ₂ O ₃ cannot be obtained. On the other hand, if the Y ₂ O ₃ content is too large, the proportion of cubic crystals increases, and the desired mechanical strength cannot be obtained.

The sintered body of the present invention is made of LaAlO ₃ , PrA
containing at least one rare earth aluminate consisting of lO ₃ and NdAlO _3. These may be either rare earth aluminates added as a raw material or rare earth aluminates produced in the production stage.

The content of the rare earth aluminate can be appropriately set according to the kind of the rare earth aluminate to be used, the use of the final product, and the like. Usually, the total amount of the stabilizer and ZrO ₂ is 1%.
The amount may be about 0.1 to 5 parts by weight, preferably 0.3 to 2 parts by weight, per 100 parts by weight. By setting the content within such a range, more excellent low-temperature thermal degradation resistance can be obtained.

The crystal phase in the zirconia sintered body of the present invention comprises a mixed phase of at least one of monoclinic and cubic and a tetragonal or a tetragonal single phase. That is, both the case of a tetragonal system alone and the case of a mixed phase of a tetragonal system and at least one of monoclinic system and cubic system are included.

In addition, in the zirconia sintered body of the present invention, as long as its effect is not impaired, the main stabilizer Y
Part of ₂ O ₃ and / or Sc ₂ O ₃ is Sm, Eu, Gd, T
It may be substituted with one or more kinds of rare earth metal oxides such as b, Dy, Ho, Er, Tm, Yb, Lu and Sc.

The low-temperature heat-degradable zirconia sintered body of the present invention has a strength at room temperature, as well as in a low-temperature heat atmosphere at 300 ° C. or lower in the air, and further in water or steam at 300 ° C. or lower. Also excellent in later bending strength. In particular, 2
Flexural strength after exposure to 50 ° C hot water for 50 hours is 90
An excellent effect of 0 MPa or more (especially 1120 MPa or more) is exhibited.

The sintered body of the present invention is more preferably (1) a sintered body having an average crystal grain size of 2 μm or less, (2) a bulk density of 5.8 g / cm ³ or more, and (3) a three-point bending strength. 1000
(4) The three-point bending strength after standing in hot water at 250 ° C. for 50 hours is 900 MPa or more (particularly 1120 MPa
a). 2. Method for producing low-temperature heat-degradable zirconia sintered body The low-temperature heat-degradable zirconia sintered body of the present invention can be produced by, for example, (1) at least one of an yttrium compound and a scandium compound, LaAlO ₃ , PrAlO _3, and NdAl.
A step of preparing a raw material mixture containing at least one rare earth aluminate composed of O ₃ and a zirconium compound; (2) a step of calcining the raw material mixture at 500 to 1200 ° C .; and (3) pulverizing the calcined body. , Molding process,
And (4) a method including a step of sintering the molded body at 1300 to 1650 ° C.

The zirconium compound is not particularly restricted but includes, for example, zirconium oxide, zirconium hydroxide, inorganic acid salts of zirconium (zirconium nitrate, zirconium sulfate, zirconium chloride, etc.) and organic acid salts of zirconium (zirconium acetate, oxalate). Zirconium citrate, zirconium citrate, zirconium malonate, etc.)
Etc. can be used.

Examples of the yttrium compound include yttrium oxide, yttrium hydroxide, yttrium carbonate, and inorganic salts of yttrium (yttrium nitrate,
Yttrium chloride, yttrium sulfate, etc.), organic acid salts of yttrium (yttrium acetate, yttrium oxalate, yttrium citrate, yttrium malonate, etc.)
Can be used.

Examples of the scandium compound include scandium oxide, scandium hydroxide, scandium carbonate, inorganic salts of scandium (such as scandium nitrate, scandium chloride, and scandium sulfate), and organic salts of scandium (such as scandium acetate, scandium oxalate, and the like).
Scandium citrate, scandium malonate, etc.) can be used.

As the rare earth aluminate, LaAlO is used.
₃ , at least one of PrAlO ₃ and NdAlO ₃ can be used.

In this case, a part or all of the rare earth aluminate is a rare earth metal element composed of La, Pr and Nd and at least one of oxides, nitrides, carbides and aluminum compounds of the rare earth metal element, Al and It may be a mixture with at least one of the oxides, nitrides and carbides. That is, a part or all of the added rare earth aluminate can be replaced with the above mixture.

Examples of the rare earth metal element oxide include:
For example, La_TwoO_Three, Pr_TwoO_11/3, Nd_TwoO_ThreeEtc.
You. Examples of the rare earth metal nitride include La.
N, PrN, NdN and the like. Rare earth metal element
Examples of elementary carbides include La_TwoC_Three, LaC_Two, La_Two
C_Three, PrC_Two, Pr_TwoC_Three, NdC_Two, Nd_TwoC_ThreeEtc.
Can be The rare earth metal element aluminum compound
For example, LaAlO _Three, PrAlO_Three, NdAlO_Three
And the like. In addition, oxides, nitrides and carbides of Al
As an object, for example, Al_TwoO_Three, AlN, Al_FourC_ThreeEtc.
I can do it. All of these may use commercially available products.
it can.

The amount of the above mixture is determined by the amount of the stabilizer and Zr
Total 100 parts by weight of O ₂ to, rare earth aluminate 0.1-5 parts by weight (preferably 0.3 to 2 parts by weight) may be set so that.

As a method for preparing the raw material mixture, a known method can be employed as long as the composition of the sintered body of the present invention can be controlled. For example, it can be prepared by a chemical synthesis method such as a neutralization coprecipitation method, a hydrolysis method, an alkoxide method (sol-gel method), and an oxide mixing method.

For example, in the case of the neutralization coprecipitation method, a solution (aqueous solution) of salts or the like of each component (for example, zirconium oxynitrate, yttrium nitrate, scandium nitrate, etc.) is mixed so as to have a predetermined composition. The mixed solution is neutralized and co-precipitated with an alkali such as ammonia or sodium hydroxide, and further, a rare earth aluminate is added thereto, and after stirring, the obtained precursor (mainly hydroxide) is washed and filtered as necessary. Thus, a raw material mixture can be obtained.

Further, in the neutralization coprecipitation method, a precipitate containing zirconium and yttrium and / or scandium is formed by neutralization coprecipitation, and the above mixture is added thereto. The raw material mixture can be obtained in the same manner as in the method.

In the case of the oxide mixing method, zirconium oxide, yttrium oxide and / or
Alternatively, a raw material mixture can be obtained by blending scandium oxide, rare earth aluminate, and the like, followed by wet mixing with a ball mill or the like and drying.

In the oxide mixing method, zirconium oxide, yttrium oxide and / or scandium oxide and the above-mentioned mixture are mixed, and then a raw material mixture can be prepared in the same manner as described above.

In the present invention, if necessary, a known binder (for example, a polyvinyl alcohol-based binder, an acrylic-based binder, or the like) may be appropriately blended into the raw material mixture. Further, if necessary, about 0.05 to 0.5% by weight of SiO ₂ or the like can be added as a sintering aid.

Next, the obtained raw material mixture is calcined.
The calcination temperature is usually about 500 to 1200 ° C, preferably 800 to 1000 ° C. The calcining atmosphere may be air or an oxidizing atmosphere. In the calcination, the raw material composition is mainly homogenized by thermal diffusion.
The sintering in the firing step can be promoted by causing a part of rO ₂ to undergo a phase transition to tetragonal. Calcination temperature is 500
When the temperature is lower than 0 ° C, such an effect cannot be sufficiently obtained. On the other hand, when the calcination temperature exceeds 1200 ° C., aggregated particles remain even after pulverization, which becomes a large breaking point, and may cause a reduction in the strength of the zirconia-based sintered body.

Subsequently, the obtained calcined body is pulverized and formed. The pulverizing method may be in accordance with a known method, for example, a ball mill, a crusher mill, a sand mill, a vibration mill, or the like. The calcined body can be obtained in the form of a powder, a lump, or the like. If necessary, any of the forms may be pulverized. The degree of pulverization can be appropriately set according to the use of the final product and the like, but usually, the average particle size may be about 0.5 to 1.5 μm. The molding method may be a known method. For example, a press molding method, an extrusion molding method, a casting molding method, a CIP method, a HIP method, or the like can be employed. In addition, in the production method of the present invention, prior to molding, kneading or granulation can be performed using a binder in advance. As described above, a known binder such as a polyvinyl alcohol-based binder or a commercially available binder can be used as the binder.

Finally, the compact is sintered. The firing temperature is usually about 1300-1650 ° C., preferably 13 ° C.
The temperature may be set to 50 to 1500 ° C. The firing atmosphere may be air or an oxidizing atmosphere. When the temperature is lower than 1300 ° C., only a sintered body having low mechanical properties can be obtained. Also,
If the temperature exceeds 1650 ° C., abnormal grain growth of crystal grains or the like occurs, so that desired strength cannot be obtained.

In the production method of the present invention, a zirconia sintered body having higher strength can be produced, particularly by pressure sintering. For example, in an example to be described later, a strength 1100 manufactured by firing after CIP molding.
Those having a MPa or more can be made into a high-strength sintered body of 1500 MPa or more by a HIP method.

[0041]

According to the present invention, not only the strength at room temperature but also a low temperature heat atmosphere of 300 ° C. or less in the air,
A zirconia sintered body excellent in bending strength after being exposed to water or steam at a temperature of 00 ° C. or lower can be provided.

The zirconia sintered body of the present invention is also excellent in conductivity. In particular, it has excellent conductivity after being exposed to water at 300 ° C. or lower or water vapor.

The zirconia sintered body of the present invention having such characteristics is expected to be applied to a wide variety of fields where the above-mentioned characteristics are required, including applications such as pulverizing members and optical fiber connector ferrule materials. You.

[0044]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples of the present invention and Comparative Examples. However, the present invention is not limited to the following examples.

Example 1 ZrO ₂ , Y ₂ O ₃ , Sc ₂ O ₃ , LaA with the composition shown in Table 1
A mixture of 10 ₃ , PrAlO ₃ and NdAlO ₃ was mixed with a resin ball mill (solvent: ion-exchanged water, ball: Zr
It was kneaded in O Ltd. _2), dried and calcined at 1000 ° C. in air. The obtained calcined powder is crushed by the above ball mill,
After spray granulation by adding a polyvinyl alcohol-based binder, the mixture was molded at 100 MPa. Next, each compact was fired in the air at a temperature shown in Table 2 for about 2 hours to obtain a zirconia sintered body.

For each of the obtained zirconia sintered bodies,
Crystal phase, crystal grain size (average crystal grain size), bulk density, three-point bending strength and three-point bending strength after autoclave test, conductivity at 600 ° C. and 600 after autoclave test
The conductivity in ° C. was measured. Table 2 shows the results.

[0047]

[Table 1]

[0048]

[Table 2]

In the present invention, the crystal phase, crystal grain size and the like of the sintered body were observed and measured as follows. (1) Crystal phase The crystal phase in the sintered body is measured by grinding the surface of the sintered body with a # 600 diamond grindstone, finishing the mirror surface with diamond grains of 1 to 5 μm, and measuring the surface by powder X-ray diffraction. Identified. (2) Crystal grain size Measurement of the crystal grain size (average crystal grain size) was performed in the following procedure. First, after the surface of the above-mentioned mirror-finished sintered body is subjected to etching treatment with hydrofluoric acid, the diameter d of a circle equal to a certain area S including 50 or more particles in an electron micrograph is calculated by the formula d. = (4S / π) ^1/2 .
And d is calculated | required about three or more visual fields of the same sample, and let the average value be an average crystal grain size. The number n of particles is the sum of the number of particles completely included in the fixed area S and の of the number of particles cut by the boundary of the fixed area (Japanese Patent Publication No. Sho 61).
-21184). (3) Flexural strength and flexural strength after autoclave test Flexural strength test method for fine ceramics (JISR)
1601), the three-point bending strength was measured. The bending strength after the autoclave test was determined by placing the sintered body in an autoclave and performing an aging test in hot water at 250 ° C. for 50 hours, and then measuring the three-point bending strength of the sintered body by the above-described test method. (4) Conductivity at 600 ° C. and 6 after autoclave test
Conductivity at 00 ° C. The sintered body heated to 600 ° C. was measured by an AC two-terminal method and determined by a complex impedance analysis method. The conductivity after the autoclave test was measured by performing the same autoclave test as in (3) above, and then measuring the sintered body heated to 600 ° C. by the same AC two-terminal method as described above, and performing complex impedance analysis. I asked. (5) Confirmation of rare earth aluminate phase For the sintered body of the embodiment, the rare earth aluminate phase (LaAlO ₃ , PrA) was measured by a high-output type powder X-ray diffraction, electron beam microanalyzer and X-ray photoelectron analyzer.
The presence of (IO ₃ , NdAlO ₃ ) was confirmed, and the amount was determined by a fluorescent X-ray analyzer.

Example 2 ZrO ₂ , Y ₂ O ₃ , La ₂ O ₃ , Pr ₂ O with the composition shown in Table 3
_A sintered body was produced in the same manner as in Example 1 _except that _11/3 , Nd ₂ O ₃ and Al ₂ O ₃ were blended.

For each of the obtained zirconia sintered bodies,
In the same manner as in Example 1, the crystal phase, crystal grain size (average crystal grain size), bulk density, three-point bending strength and three-point bending strength after the autoclave test, and conductivity at 600 ° C and 600 ° C after the autoclave test were measured. The conductivity was measured. Table 4 shows the results.

In the sample No. The amounts of rare earth aluminates in the zirconia sintered bodies of Nos. 39 to 41 were 0.65% by weight (sample No. 39) and 1.3% by weight, respectively.
(Sample No. 40) and 2.6% by weight (Sample No. 4)
1). On the other hand, in the sintered body of the comparative example, the presence of rare earth aluminate was not recognized.

[0053]

[Table 3]

[0054]

[Table 4]

The sintered body of the present invention containing a predetermined amount of rare earth aluminate, especially after the autoclave test, has a capacity of 120%.
It can be seen that a high bending strength of 0 MPa or more is maintained.

Example 3 Zirconium oxynitrate (ZrO (NO ₃ ) ₃ ) and yttrium nitrate or scandium nitrate were mixed and dissolved to have the composition shown in Table 1 (remarks: Example), and ammonia water was added thereto. Thus, a hydroxide coprecipitated sol was obtained. The precipitate was dried at 120 ° C., calcined at 1000 ° C., added with a rare earth aluminate shown in Table 1 at the time of crushing, and fired in the same manner as in Example 1 to obtain a zirconia sintered body. The properties of the obtained zirconia sintered body were the same as those in Example 1.

Example 4 Sample No. 1 of Example 1 A sintered body was produced in the same manner as in Example 1 except that the composition was the same as that of Example 4, and the granulation was performed by a tumbling granulation method so that the sintered body had a diameter of 1 cm. However, the firing temperature was 1500 ° C.

Next, it is rarely performed at a site actually used as a crushing medium,
The thermal stability in a drying process at 200 ° C. after washing with water, which is assumed to be the most severe use condition that induces thermal degradation, was examined.

This was evaluated by performing an abrasion test using the obtained sintered body as a grinding medium. The wear test was performed using a planetary ball mill. 200 g of the media previously washed with water for each test batch was held in a drier at 200 ° C. for 50 hours, and allowed to cool to room temperature.
The medium was placed in a 500 ml resin pot together with 00 ml, and rotated at 500 rpm for 5 hours to determine the wear rate of the media before and after the test. Table 5 shows the results.

In Table 5, the test batch number indicates the number of times the above-mentioned wear test was performed. That is, test batch 1
Indicates that the above-mentioned abrasion test was performed once, test batch 2 was a single abrasion test for test batch 1, test batch 3 was a further abrasion test for test batch 2, and test batch 4 Indicates that the test batch 3 was further subjected to the abrasion test once.

Table 5 shows a sample N of Example 1 for comparison.
o. The results of the same test performed on the pulverizing media manufactured in the same manner as the above-mentioned media using the same composition as Comparative Example 1 are also shown.

[0062]

[Table 5]

As is clear from the results shown in Table 5, the pulverizing member using the zirconia sintered body of the present invention has a low wear rate and excellent thermal stability. It can be seen that excellent abrasion resistance can be exhibited even under various use conditions. Further, the abrasion resistance of the media using the zirconia sintered body of the present invention shown in Table 3 was almost the same as when the above-mentioned heat deterioration treatment (holding in a dryer at 200 ° C. for 50 hours) was not performed. .

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G031 AA07 AA08 AA09 AA12 AA29 BA01 BA18 BA20 BA21 CA01 CA04 GA01 GA02 GA11

Claims (8)

[Claims] 1. ZrO ₂ as a main component, Y ₂ O ₃ and Sc ₂ O
_3. A zirconia sintered body containing at least one stabilizer of (3), wherein (1) the molar ratio of the stabilizer to ZrO ₂ is 1.
5: 98.5 to 4:96, (2) LaAlO ₃ ,
It contains at least one kind of rare earth aluminate composed of PrAlO ₃ and NdAlO ₃ , and (3) consists of a mixed phase of at least one kind of monoclinic and cubic and a tetragonal or a tetragonal single phase. Zirconia sintered body resistant to low temperature heat deterioration. 2. The low-temperature heat-degradable zirconia-based sintered material according to claim 1, wherein the content of the rare earth aluminate is 0.1 to 5 parts by weight based on 100 parts by weight of the total of the stabilizer and ZrO _2. body. 3. The low-temperature heat-degradable zirconia sintered body according to claim 1, wherein the three-point bending strength after standing in hot water at 250 ° C. for 50 hours is 900 MPa or more. 4. The sintered body has an average crystal grain size of 2 μm or less, (2) a bulk density of 5.8 g / cm ³ or more, and (3) 3
The low-temperature heat-degradable zirconia sintered body according to claim 1 or 2, wherein the point bending strength is 1000 MPa or more, and (4) the three-point bending strength after standing in hot water at 250 ° C for 50 hours is 900 MPa or more. 5. The method for producing a zirconia-based sintered body having low temperature resistance to low-temperature heat deterioration according to claim 1, wherein (1)
Preparing a raw material mixture containing at least one of a yttrium compound and a scandium compound, at least one of rare earth aluminates composed of LaAlO ₃ , PrAlO ₃ and NdAlO _3, and a zirconium compound;
(2) a step of calcining the raw material mixture at 500 to 1200 ° C., (3) a step of pulverizing and molding the calcined body, and (4) a step of sintering the molded body at 1300 to 1650 ° C. A manufacturing method, comprising: 6. A method according to claim 1, wherein the rare earth aluminate comprises at least one selected from the group consisting of La, Pr, and Nd, and at least one of oxides, nitrides, carbides, and aluminum compounds of the rare earth metal elements. The method for producing a low-temperature heat-degradable zirconia sintered body according to claim 5, wherein a mixture with at least one of an oxide, a nitride, and a carbide is used. 7. A material for a pulverized member comprising the sintered body according to claim 1. 8. An optical fiber connector ferrule material comprising the sintered body according to claim 1.