JP2003192452A - Zirconia powder and sintered compact thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide powder which has satisfactory compactibility, and gives a sintered compact having excellent sinterability and properties as those of a sintered compact, and to provide a sintered compact thereof. <P>SOLUTION: The zirconia powder contains Y<SB>2</SB>O<SB>3</SB>in the range of 0.1 to 6 wt.%, and Al<SB>2</SB>O<SB>3</SB>in the range of 0.1 to 1 wt.%, and has a sodium content of ≤0.01 wt.% expressed in terms of Na<SB>2</SB>O, an iron content of ≤0.001 wt.% expressed in terms of Fe<SB>2</SB>O<SB>3</SB>, and a titanium content of ≤0.05 wt.% expressed in terms of TiO<SB>2</SB>. The electrical conductivity of the zirconia powder when slurried in 30 wt.% with pure water is ≤300 μS/cm, and its pH lies within the range of 5 to 7. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to zirconia having excellent formability, sinterability, and mechanical properties used for structural materials such as precision machined parts, crusher members, crushing media, and optical member parts. The present invention relates to powder and its sintered body.

[0002]

2. Description of the Related Art High-strength zirconia is widely used as a constituent material for precision machined parts, parts for optical members, sliding parts of crushing balls and crushers, and blades by taking advantage of its high strength and high toughness. Has been done. Conventionally, as a zirconia powder used for these purposes and a method for producing the same, there are known methods such as a thermal decomposition method, a coprecipitation method, and a hydrolysis method (for example, Patent Document 1).

However, there is an increasing demand for higher performance, and in some cases, the method described in Patent Document 1 has insufficient characteristics. That is, in recent years, there has been an increasing demand for very small products such as optical fiber connector parts and products requiring high mechanical properties, and in the production of those products, the powder formability and sintered body properties described above are not sufficient. There have been cases where this is not always enough. There is a need for higher sinter properties, quality weatherability, and for powders from which such sinters can be obtained.

[0004]

[Patent Document 1] Japanese Patent Laid-Open No. 2001-089145

[0005]

Therefore, the present invention provides a zirconia powder and a zirconia powder which have good formability, excellent sinterability, mechanical properties, and excellent weather resistance. It is an issue.

[0006]

The present inventors have found that the moldability,
The present invention has been achieved as a result of extensive studies on zirconia powder and a sinter having good sinterability, which can provide a sinter having excellent mechanical properties and quality weather resistance. That is, the present invention has the following configuration. (1) The zirconia powder contains Y ₂ O ₃ in the range of 0.1 to 6% by weight and Al ₂ O ₃ in the range of 0.1 to 1% by weight, and the content of sodium element is 0.01 in terms of Na ₂ O. weight%
Hereinafter, the content of the iron element is 0.001% by weight or less in terms of Fe ₂ O ₃ , and the content of the titanium element is 0.0 in terms of TiO _2.
5 wt% or less, and the zirconia powder with pure water 3
Electric conductivity of 300 μS when slurried into 0 wt%
/ Cm or less, pH is the range of 5-7, The zirconia powder characterized by the above-mentioned. (2) BET specific surface area is 8 to 17 m ² / g, average particle diameter of primary particles is 0.04 to 0.08 μm, and average particle diameter of secondary agglomerated particles is 0.3 to 1.0 μm, and The zirconia powder according to claim 1, which has a monoclinic crystal ratio of 20 to 40%. (3) A powder containing zirconia as a main component, the powder being molded under the condition of 98 MPa (1 ton / cm ² ) to give 1
The relative density of the sintered body obtained by sintering at 350 ° C. for 3 hours is 9
8% or more, the change rate of the average crystal grain size of the sintered body at 1350 ° C. for 3 hours and 1450 ° C. for 3 hours is 50% or less, and the change rate of the relative density of the sintered body is 2% or less, and 13
A zirconia powder characterized in that the rate of change of the average crystal grain size of the sintered body at 75 ° C. for 2 hours and 1375 ° C. for 9 hours is 10% or less and the rate of change of the relative density of the sintered body is 1% or less. (4) A sintered body obtained by sintering the zirconia powder according to any one of (1) to (3). (5) A sintered body obtained by sintering a powder containing zirconia as a main component, wherein the relative density of the sintered body is 98% or more, the average crystal grain size is 0.4 μm or less, and the crystal grain is A sintered body having a standard deviation of diameter of 0.15 or less. (6) A sintered body obtained by sintering a powder containing zirconia as a main component, wherein the relative density of the sintered body is 98% or more, the average crystal grain size is 0.4 μm or less, and the crystal grain is A sintered body having a diameter variation coefficient of 60% or less. (7) Sintering according to any one of (4) to (6), wherein the chromaticity is such that Y is 50 to 70, and both δx and δy are more than 0.0000 and 0.0150 or less. body. Is.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below.

The zirconia powder of the present invention contains Y ₂ O in the raw material.
It is necessary to include ₃ in the range of 0.1 to 6% by weight.
In order for zirconia to exhibit the characteristics of high strength and toughness, by adding an appropriate amount of a stabilizer such as Y ₂ O ₃ , the crystal structure of zirconia, which is usually a monoclinic crystal at room temperature, has a large number of tetragonal crystals. The crystal structure can be occupied. When the content of Y ₂ O ₃ is less than 0.1% by weight, the tetragonal crystal in zirconia is not stabilized, and the proportion of monoclinic crystal present at room temperature tends to increase, so that high strength tends not to be obtained, which is not preferable.
On the other hand, if the content exceeds 6% by weight, on the contrary, the tetragonal crystal tends to be completely stabilized, stress-induced transformation does not easily occur at room temperature, and high strength tends not to be obtained, which is not preferable. The content of Y ₂ O ₃ is more preferably in the range of 2.5 to 5.5% by weight.

The zirconia powder of the present invention contains Al in the raw material.
_It is necessary to include ₂ O ₃ in the range of 0.1 to 1% by weight. The high strength of zirconia is due to the stress-induced transformation of tetragonal to monoclinic. By adding a small amount of Al ₂ O ₃ , compressive stress is applied to zirconia. In addition, Al ₂
O ₃ has a function of strengthening the grain boundary and can withstand even a strong stress against pulling, so that the strength becomes higher. Also,
By adding a small amount of Al ₂ O ₃ , it becomes a powder having excellent low-temperature sinterability. Further, since zirconia and alumina react only slightly, they have a function of suppressing the growth of crystal grains during high temperature sintering. The content of Al ₂ O ₃ is 0.
If it is less than 1% by weight, it is too small and the effect is small. On the contrary, if it exceeds 1% by weight, the toughness tends to decrease, which is not preferable. It is more preferable that the content of Al ₂ O ₃ is in the range of 0.2 to 0.5% by weight.

The zirconia powder of the present invention has a sodium element content of 0.01 wt% or less in terms of Na ₂ O, an iron element content of 0.001 wt% or less in terms of Fe ₂ O ₃ , and titanium element content. The content must be 0.05% by weight or less in terms of TiO ₂ . It is known that the presence of sodium element improves the strength of the sintered body. However, when sodium element is present in the powder manufacturing process, the powder particles are strongly bound to each other during the powder firing, and a hard aggregate is formed. Hard agglomerates do not completely unravel during the crushing process and form irregular shapes and coarse particles. Powder containing such irregular shape and coarse particles,
For example, during injection molding, there are problems such as poor fluidity and low sinterability with respect to sinterability. Therefore, it is necessary to control the amount of sodium element. In order to stably perform the sintering, it is desirable that the sodium element content is 0.005% by weight or less in terms of Na ₂ O.

When a large amount of iron element is present in the zirconia powder, the phase diagram is distorted, the stability of zirconia is changed, and the growth of crystal grains is accelerated. Then, giant particles are generated, and as a result, necessary characteristics of the sintered body cannot be obtained, which is not preferable. Preferably 0.002 in terms of Fe ₂ O ₃
It is preferably less than 05% by weight. Further, when the amount of iron increases, the color tone of the sintered body tends to be yellow, and the light reflectance tends to decrease.

When the titanium element is contained in the zirconia powder,
Titanium element has high activity, and further increases in activity when light, heat, etc. are applied, which may deteriorate zirconia.
Also, since it reacts with alumina to form needle-like crystals called alumina titanate, the desired sintered body properties may not be obtained. The content of titanium element is more preferably 0.005% by weight or less in terms of TiO ₂ .

The zirconia powder of the present invention has an electric conductivity of 300 when the powder is slurried with pure water in an amount of 30% by weight.
It is necessary to be less than μS / cm. Generally, in powder, substances added at the time of synthesizing the powder and replication components generated at the time of synthesis remain, and when the powder is slurried,
Those residual components are eluted into the slurry and become ions. In the case of adding a synthetic resin or the like to the powder made into a slurry, the presence of extra ions may prevent adsorption of the synthetic resin added as a binder or a lubricant to the powder, or may cause excessive adsorption. The effect may not be fully exerted. Therefore, it is important to select a highly pure raw material that does not cause these phenomena. The electrical conductivity is preferably 100 μS / cm.

The pH of the slurry must be in the range of 5-7. The slurry having a pH value in the above range is weakly agglomerated while being dispersed, and the spray-dried granulated powder is a powder in which agglomeration of particles is weak. For example, when producing an injection compound, it is easy to knead with a binder and a uniform compound can be produced. If the pH of the slurry is less than 5 or more than 7, the spray-dried powder becomes a strongly agglomerated hard powder, which is not preferable. The strongly agglomerated powder may not be uniform because the agglomeration is not loosened when producing a compound for injection molding, for example. In addition, the fluidity may be poor and molding may not be possible.

The zirconia powder of the present invention preferably has a BET specific surface area of 8 to 17 m ² / g. The BET specific surface area in the present invention refers to a value measured by the BET one-point method according to the method for measuring the specific surface area according to JIS-R1626 "Fine ceramic powder gas adsorption BET method". If the BET specific surface area is less than 8 m ² / g, the sinterability tends to be low, and a dense and uniform sintered body tends not to be obtained. When the BET specific surface area exceeds 17 m ² / g, the particles are fine and the moldability tends to decrease. Furthermore, the crystal grains may grow too fast during sintering to cause aggregation, resulting in a non-uniform sintered body. BET specific surface area is 1
It is more preferably ^{2 to} 17 m ² / g.

The zirconia powder of the present invention preferably has an average primary particle size of 0.04 to 0.08 μm. The range where the average particle size of the primary particles is 0.04 to 0.08 μm is a region excellent in moldability and sinterability. If the average particle size exceeds 0.08 μm, the sinterability tends to decrease, and
If it is less than 04 μm, the moldability tends to be low and it becomes difficult to control the sinterability. Here, as the average particle diameter of the primary particles, a value measured by an electron microscope is used. Specifically, the average equivalent circle diameter of the primary particles of the photographed image is obtained using an image processing device, and the average equivalent circle diameter is taken as the average particle diameter of the primary particles.

The zirconia powder of the present invention preferably has an average particle size of secondary agglomerated particles of 0.3 to 1.0 μm.
Here, the secondary agglomerated particle size refers to the particle size of the volume-based distribution measured using a particle size distribution measuring device, and the average particle size refers to the so-called median size whose cumulative distribution corresponds to 50%. Say. If the average particle size is less than 0.3 μm, the particles are too small, resulting in poor moldability and difficulty in controlling sintering. On the other hand, when the average particle size exceeds 1.0 μm,
Sinterability tends to decrease, and it becomes difficult to obtain a dense and uniform sintered body.

The zirconia powder of the present invention has a monoclinic crystal ratio of 2
It is preferably 0 to 40%. The monoclinic crystal ratio in the present invention is a value obtained by an X-ray diffraction method. The powder having a monoclinic crystal ratio in the range of 20 to 40% has good moldability, and the sintered body has high bending strength. If the monoclinic crystal ratio exceeds 40%, the bending strength may decrease, and if it is less than 20%, the bulk density of the powder is low, and the shrinkage ratio may increase, possibly causing distortion.

Next, another zirconia powder of the present invention is a powder containing zirconia as a main component, and the powder is 98M.
1350 ° C after molding under the condition of Pa (1 ton / cm ² ).
The relative density of the sintered body obtained by sintering for 3 hours is 98% or more, the rate of change of the average crystal grain size of the sintered body at 1350 ° C. for 3 hours and 1450 ° C. for 3 hours is 50% or less, and Of the relative density of 2% or less, and 1375 ℃ 2
And the change rate of the average crystal grain size of the sintered body at 1375 ° C. for 9 hours is 10% or less, and the change rate of the relative density of the sintered body is 1 or less.
% Or less. A sintered body used for an optical member or the like needs to have excellent mechanical properties and quality weather resistance. A zirconia powder satisfying these requirements needs to have a highly controlled sinterability, as described herein.

Here, the components other than zirconia are not particularly limited, but the smaller the impurities, the better, and preferably the zirconia component is 90% by weight or more.

The sintered body of the present invention is obtained by sintering the above-mentioned zirconia powder. Preferably, the relative density of the sintered body is 98% or more, the average crystal grain size is 0.4 μm or less, and the standard deviation of the crystal grain size is 0.15 or less.
The sintered body of the present invention preferably has a relative density of 98% or more, an average crystal grain size of 0.4 μm or less, and a coefficient of variation of the average crystal grain size of 60% or less. It is a union. In order for the sintered body to achieve high strength, high toughness, wear resistance, and weather resistance, the relative density is 98.
% Or more is preferable. In particular, in order to have excellent weather resistance, it is preferable to reduce the average crystal grain size to 0.4 μm or less. Further, it is preferable that the standard deviation is 0.15 or less or the coefficient of variation is 60% or less as a condition that there are no giant particles or extremely small particles and the particles are aligned. The sintered body satisfying these conditions can be obtained by using the zirconia powder of the present invention and appropriately controlling the sintering conditions such as the sintering temperature and the sintering time.

The chromaticity of the sintered body of the present invention is such that Y is 50 to 7
0 and both δx and δy exceed 0.0000 and 0.01
It is preferably 50 or less. Chromaticity is generally Y,
It is represented by three values of x and y. Y represents lightness, and x and y represent color. A point having no color is called a W point (white point), and x = 0.3101 and y = 0.3161. High brightness gives white, low brightness gives black. δx and δy represent the difference from the white point, and the smaller this value, the whiter the image. Preferably both δx and δy are 0.010.
It is the following.

The chromaticity can also be an index of the content of impurities. That is, in order for the sintered body to have characteristics such as a high sintered density, a small crystal grain size, and a uniform size, it is important that the amount of impurities is small.
Absorption of light occurs when impurities are contained, Y is low,
The values of δx and δy increase. For example, if impurities that affect the properties of the sintered body are included, the Y value becomes less than 50, and both δx and δy may exceed 0.015.

The sintered body of the present invention is preferably used for optical members and optical applications. In these applications, it is desired that light is not attenuated so much, and the sintered body of the present invention absorbs light little and has high reflectance.

[0025]

EXAMPLES Examples will be described below.

The physical properties of the examples were measured and evaluated as follows.

(1) Y ₂ O ₃ , Al ₂ O ₃ , Fe ₂ O ₃ ,
Quantitative analysis powder of TiO ₂ About 0.1 g was weighed in a platinum crucible and melted with potassium hydrogen sulfate. ICP
Elements were quantified by optical emission spectroscopy. This quantitative value was converted into oxide. As the ICP emission spectrum analyzer, SPS1200VR type manufactured by Seiko Instruments Inc. was used.

(2) Quantitative analysis of elemental sodium About 0.1 g of powder was weighed in a platinum crucible and melted with potassium hydrogen sulfate. This was dissolved in dilute nitric acid to make a constant solution, and the element was quantified by atomic absorption spectrometry. This quantitative value was converted into oxide. As an atomic absorption spectrometer, Shimadzu AA-
600 was used.

(3) 210 g of pure water having an electric conductivity of 5 μS / cm and 90 g of zirconia powder were placed in a beaker having an electric conductivity of 300 cc, and after stirring well, a 30 wt% slurry was prepared in an ultrasonic generator for 10 minutes. did. The electric conductivity of this slurry was measured using an electric conductivity meter. As the electric conductivity meter, LAB conductivity meter DS-12 manufactured by HORIBA, Ltd. was used.

(4) pH The powder was made into a slurry having a concentration of 30 wt%, and the pH of the slurry was measured using a pH meter. The method for producing the slurry is the same as the content described in the method for measuring electrical conductivity. Horiba D-14 was used as the pH meter.

(5) BET Specific Surface Area The BET specific surface area was measured by the BET one-point method in accordance with JIS-R1626 "Method for measuring specific surface area of fine ceramic powder by gas adsorption BET method".

(6) The average particle size powder of the secondary agglomerated particles was made into a slurry having a concentration of 30 wt%. The method for producing the slurry is the same as the content described in the method for measuring electrical conductivity. The secondary particle size of the prepared slurry was measured using a particle size distribution meter, and the so-called median size corresponding to a cumulative distribution of 50% was taken as the average particle size. Nikkiso Microtrac Particle Size Analyzer 7995-10SRA
Was used.

(7) Average Particle Size of Primary Particles The powder was observed using a transmission electron microscope, and 100,000 times photographs were taken at five arbitrary points. The average equivalent circle diameter of the primary particles of the photographed photograph was determined using an image processing device. The average circle equivalent diameter was defined as the average particle diameter of the primary particles. A JEM2000EX manufactured by JEOL was used as the transmission electron microscope, and a TV image processor EXCEL manufactured by Nippon Avionics was used as the image processing device.

(8) The monoclinic crystal powder was subjected to X-ray diffraction, and its diffraction intensity (area of diffraction peak)
Was calculated from the following formula. However, the diffraction intensity used the value after correction by Lorentz factor.

[0035]

[Equation 1]

An X-ray diffractometer manufactured by Rigaku Denki Co., Ltd. was used.

(9) The chromaticity powder of the sintered body was 98 MPa (1 ton / cm) by using a CIP device.
Molded under the conditions of ² ), the molded body is φ25 × L25mm
And was sintered at a temperature of 1350 ° C. for 2 hours.
The flat surface portion of the sintered body was mirror-finished, and the chromaticity (Y, x, y) was measured using a color computer. The Y value represents lightness, and the x and y values represent color. For the chromaticity, the difference from the W point (white point) was calculated by the following formula. δx = │x-0.3101│ δy = │y-0.3161│ As a color computer, SM-4 manufactured by Suga Test Instruments Co., Ltd.
As the CIP device, a Mitsubishi cold isotropic pressure press made by Mitsubishi Heavy Industries was used.

(10) The relative density of the powder was 98 MPa (1 ton / cm) using a CIP device.
Molded under the conditions of ² ), the molded body is φ25 × L25mm
It was processed into a cylinder and sintered. The sintered density of the sintered body was measured by the Archimedes method. The value obtained by dividing the value obtained by dividing the sintered density by the theoretical density by 100 was taken as the relative density. here,
The theoretical density was 6.08 g / cm ³ .

(11) Relative Density Change Rate-1 The relative densities of the sintered product at 1350 ° C. for 3 hours and the sintered product at 1450 ° C. for 3 hours were measured by the same method as the method for measuring the relative density. The rate of change of relative density with respect to the sintering temperature was obtained from the following formula. Change rate of relative density with respect to temperature (%) = (B−A) / A
× 100 A: Relative density of sintered product at 1350 ° C. for 3 hours B: Relative density of sintered product at 1450 ° C. for 3 hours (12) Relative density change rate −2 (11)
The relative density of the sintered product at 75 ° C. for 2 hours and the sintered product at 1375 ° C. for 9 hours was measured. The change rate of the relative density with respect to the sintering time was obtained from the following formula. Change rate of relative density with respect to time (%) = (D−C) / C
× 100 C: Relative density of sintered product at 1375 ° C. for 2 hours D: Relative density of sintered product at 1375 ° C. for 9 hours (13) Average crystal particle size The powder was 98 MPa (1 ton / cm 2) using a CIP device.
Molded under the conditions of ² ), the molded body is φ25 × L25mm
It was processed into a cylinder and sintered. What is the sintering temperature and sintering time? The flat surface of the sintered body is mirror-finished and the temperature is 50 ° C from the sintering temperature.
Thermally etched at low temperature for 3 hours. The sample was observed using a scanning electron microscope, and a photograph of 30,000 times was taken at five arbitrary points. Using an image processing device, the average equivalent circle diameter of the crystal grains in the photographed photograph was determined.
The average equivalent circle diameter was defined as the average crystal grain size. In addition, the standard deviation was determined from the crystal grain size.

Here, S-510 manufactured by Hitachi was used as the scanning electron microscope, and TV image processor EXCEL manufactured by Nippon Avionics was used as the image processing apparatus.

(14) Coefficient of variation of crystal grain size The coefficient of variation was determined by the following formula using the average crystal grain size (x) determined in (13) and the standard deviation (σ).

Coefficient of variation (%) = σ / x × 100 (15) Rate of change of average crystal grain size with respect to sintering temperature By the same method as the method for measuring the average crystal grain size, 135
The average crystal grain diameters of the sintered product at 0 ° C. for 2 hours and the sintered product at 1450 ° C. for 2 hours were measured. The rate of change of the average crystal grain size with respect to the sintering temperature was obtained from the following formula. Average crystal grain diameter change rate (%) with respect to sintering temperature = (F-
E) / E × 100 E: Average crystal particle size of sintered product at 1350 ° C. for 3 hours F: Average crystal particle size of sintered product at 1450 ° C. for 3 hours (16) Rate of change of average crystal particle size with respect to sintering time Same as (15), 137 with sintered product at 1375 ° C for 2 hours
The average crystal grain size of the sintered product was measured at 5 ° C. for 9 hours. The rate of change of the average crystal grain size with respect to the sintering time was obtained from the following formula. Average crystal grain size change rate (%) = (H-
G) / G × 100 G: Relative density of average crystal grain size of sintered product at 1375 ° C. for 2 hours H: Average density of crystal grain size of sintered product at 1375 ° C. for 9 hours (17) Bending strength 98 MPa (1 ton / cm
^It was molded under the conditions of ² ) and the molded body was sintered at a temperature of 1350 ° C. for 2 hours. A sample piece of 3 × 4 × about 40 mm was cut out from the sintered body, and the three-point bending strength was measured according to JIS-R1601 “Bending strength test method for fine ceramics”.

(18) Hot water life evaluation powder is 98 MPa (1 ton / cm) by using a CIP device.
Molded under the conditions of ²⁾ , the molded body is φ25 × L25mm
It was processed into a cylinder and sintered. The monoclinic crystal ratio of the sintered body was measured in the same manner as the powder monoclinic ratio measurement, and after confirming that there was no monoclinic crystal, it was held in hot water at 140 ° C. for 24 hours using an autoclave. The monoclinic crystal ratio of the hydrothermally treated sintered body was measured again, and those in which monoclinic crystals were not confirmed were evaluated as ◯, and those in which monoclinic crystals were confirmed were evaluated as ×. ○ means pass.

Example 1 A ZrOCl ₂ solution having a Y ₂ O ₃ concentration of 5.0 to 5.4 was used.
A YCl ₃ solution was added so that the weight% became Al ₂ O ₃
AlCl so that the concentration becomes 0.2 to 0.4% by weight.
_After adding ₃ solutions, ammonia water was added to coprecipitate the hydroxide, and the coprecipitate was washed with water by a centrifuge and dried,
It was calcined at 0 to 1000 ° C. for 2 hours. The obtained calcined body is
After wet grinding with pure water for 6 hours using a medium stirring mill,
Fine particles and coarse particles were removed with a classifier and washed with water using an ultrafiltration device. The slurry after washing with water was spray-dried. Coarse particles were removed from the obtained powder with a classifier and deironed with an iron remover. The powder of No. 1 and 3 described in the example table was obtained. ZrOCl ₂ , YCl ₃ and AlCl ₃ used as raw materials
Selected the one with few impurities. About the obtained powder, sodium element, iron element, titanium element, Y ₂ O ₃ ,
The quantitative analysis of Al ₂ O ₃ , electrical conductivity, pH, BET specific surface area, average particle size of secondary agglomerated particles, average particle size of primary particles measured by an electron microscope, and monoclinic crystal ratio were measured. A molded body was produced from this powder, a sintered body was produced at various temperatures, and the relative density and crystal grain size of the sintered body were measured. From these, the rate of change of relative density with respect to sintering temperature, the rate of change of relative density with respect to sintering time, the rate of change of crystal particle diameter with respect to sintering temperature, and the rate of change of crystal particle diameter with respect to sintering time were obtained. The results are shown in Tables 1 to 3.

Example 2 A ZrOCl ₂ solution having a Y ₂ O ₃ concentration of 5.0 to 5.2 was used.
YCl ₃ solution was added and mixed so as to be a weight% of the mixture, and aqueous ammonia was added to coprecipitate the hydroxide. The coprecipitate was washed with water by a centrifuge, dried and then at 800 to 1000 ° C. for 2 hours. It was calcined. Al ₂ O ₃ is added to the obtained calcined body in an amount of 0.2 to
0.4 wt% was added, and the mixture was wet pulverized with pure water for 6 hours using a medium stirring mill, then fine particles and coarse particles were removed with a classifier, and washed with water using an ultrafiltration device. The slurry after washing with water was spray-dried. Coarse particles were removed from the obtained powder with a classifier and deironed with an iron remover. No. described in the example table
Four and five powders were obtained. ZrOC used as the raw material
L ₂ , YCl ₃ , and Al ₂ O ₃ were selected to have few impurities. The obtained powder was evaluated in the same manner as in Example 1. The results are shown in Tables 1 to 3.

Example 3 To a ZrOCl ₂ solution, a YCl ₃ solution was added and mixed so that the Y ₂ O ₃ concentration was 5.4% by weight, and a sodium hydroxide solution was added to coprecipitate a hydroxide. The precipitate was washed with a centrifuge, dried, and then calcined at 800 to 1000 ° C. for 2 hours. Al ₂ O ₃ is added to the obtained calcined body in an amount of 0.2 to
0.4 wt% was added, and after wet pulverizing with pure water for 8 hours using a medium stirring mill, fine particles and coarse particles were removed with a classifier, and washed with water using an ultrafilter. The slurry after washing with water was spray-dried. Coarse particles were removed from the obtained powder with a classifier and deironed with an iron remover. No. 2 described in the example table
Of powder was obtained. ZrOCl ₂ and YC used as raw materials
l ₃ and Al ₂ O ₃ were selected to have few impurities, and the coprecipitation reaction was carried out at a concentration half that of Examples 1 and 2. The obtained powder was evaluated in the same manner as in Example 1. The results are shown in Tables 1 to 3.
Shown in.

Example 4 The powders Nos. 1 to 5 obtained in Examples 1, 2 and 3 were used.
Sintering was performed at 1350 ° C. for 2 hours to produce a sintered body, and the relative density, bending strength, average crystal particle diameter, standard deviation of crystal particle diameter, variation coefficient, Y, δx, δy, hot water treatment of the sintered body The subsequent monoclinic rate was measured. The results are shown in Tables 4-5.

Comparative Example 1 A ZrOCl ₂ solution having a Y ₂ O ₃ concentration of 5.0 to 5.7 was used.
A YCl ₃ solution was added and mixed so as to have a weight percentage, sodium hydroxide was added to coprecipitate a hydroxide, the coprecipitate was washed with water, dried, and then calcined at 700 to 1000 ° C. for 2 hours. . Al ₂ O ₃ was added to the obtained calcined body in an amount of 0 to 1.2% by weight, wet-milled for 10 hours using a medium stirring mill, and spray-dried to obtain a powder. Coarse particles were removed from the obtained powder with a classifier and deironed with an iron remover. No described in the comparative example
Powders 6 and 7 were obtained. Evaluation was performed in the same manner as in Example 1. The results are shown in Tables 6-8.

Comparative Example 2 A YCl ₃ solution was added to a ZrOCl ₂ solution so as to have a Y ₂ O ₃ concentration of 5.4% by weight and mixed, and sodium hydroxide was added to coprecipitate a hydroxide to coprecipitate. The product was washed with water, dried, and then calcined at 800 to 1000 ° C. for 2 hours. 0.3% by weight of Al ₂ O ₃ was added to the obtained calcined body, the mixture was wet-ground for 3 hours using a medium stirring mill, and spray-dried to obtain a powder. Coarse particles were removed from the obtained powder with a classifier and deironed with an iron remover. The powder of No8 described in the comparative example was obtained.
Evaluation was performed in the same manner as in Example 1. The results are shown in Tables 6-8.

Comparative Example 3 Comparative Examples 1 and 2 The powders Nos. 6 to 8 obtained were used, and 135
Sintering was performed at 0 ° C. for 2 hours to prepare a sintered body, and the relative density, bending strength, average crystal grain size, standard deviation of crystal grain size, Y, δx, δy, and the single body after hot water treatment of the sintered body were prepared. The crystallinity was measured. The results are shown in Tables 9-10.

Comparative Example 4 Comparative Examples 1 and 2 Using the obtained powders of Nos. 6-8, 150
Sintering is performed at 0 ° C. for 2 hours to produce a sintered body, and the relative density, bending strength, average crystal grain size, standard deviation of crystal grain size, variation coefficient, Y, δx, δy, hot water treatment of the sintered body The subsequent monoclinic rate was measured. The results are shown in Nos. 9 to 11 of Tables 9 to 10.

The evaluation results are shown in Tables 1-10. As is apparent from the table, the zirconia powders of Examples have mechanical properties,
It is possible to obtain a sintered body having excellent weather resistance. on the other hand,
In Comparative Examples outside the scope of the present invention, the sinterability of the powder was poor, and the sintered body was inferior in mechanical characteristics, quality characteristics, and other characteristics of the sintered body.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

[0056]

[Table 4]

[0057]

[Table 5]

[0058]

[Table 6]

[0059]

[Table 7]

[0060]

[Table 8]

[0061]

[Table 9]

[0062]

[Table 10]

[0063]

Industrial Applicability According to the present invention, it is possible to provide a powder and a sintered body thereof which have a good moldability and give a sintered body excellent in sinterability and sintered body characteristics.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4G030 AA03 AA12 AA16 AA27 AA36                       BA01 BA18 CA01 CA04 GA11                       GA27                 4G031 AA01 AA08 AA11 AA12 AA21                       AA29 BA01 BA18 CA04 GA01                       GA03 GA11                 4G048 AA02 AC08 AD03

Claims (7)

[Claims] 1. Zirconia powder contains Y ₂ O _{3 in an amount} of 0.1-6.
% By weight, containing Al ₂ O ₃ in the range of 0.1 to 1% by weight,
The content of sodium element is 0.01% by weight or less in terms of Na ₂ O, and the content of iron element is 0.001 in terms of Fe ₂ O _3.
Weight% or less, the content of titanium element in terms of TiO ₂ is 0.
It is not more than 05% by weight, and the electrical conductivity of the zirconia powder when slurried in pure water at 30% by weight is 300 μ.
A zirconia powder having an S / cm or lower and a pH in the range of 5 to 7. 2. The BET specific surface area is 8 to 17 m ² / g, the average particle diameter of the primary particles is 0.04 to 0.08 μm, and the average particle diameter of the secondary agglomerated particles is 0.3 to 1.0 μm, The monoclinic crystal ratio is 20 to 40%.
The zirconia powder according to. 3. A powder containing zirconia as a main component, which is molded at 1350 ° C. after molding under the condition of 98 MPa.
The relative density of the sintered body obtained by time sintering is 98% or more, the change rate of the average crystal grain size of the sintered body at 1350 ° C. for 3 hours and 1450 ° C. for 3 hours is 50% or less, and The change rate of the relative density is 2% or less, the change rate of the average crystal grain size of the sintered body at 1375 ° C. for 2 hours and 1375 ° C. for 9 hours is 10% or less, and the change rate of the relative density of the sintered body is 1%. %
The zirconia powder characterized by being the following. 4. A sintered body obtained by sintering the zirconia powder according to claim 1. 5. A sintered body obtained by sintering powder containing zirconia as a main component, wherein the relative density of the sintered body is 98% or more, and the average crystal particle size is 0.4 μm or less, and A sintered body having a standard deviation of crystal grain diameter of 0.15 or less. 6. A sintered body obtained by sintering a powder containing zirconia as a main component, wherein the relative density of the sintered body is 98% or more, and the average crystal grain size is 0.4 μm or less, and A sintered body having a variation coefficient of crystal particle diameter of 60% or less. 7. The chromaticity is such that Y is 50 to 70 and δx and δ
Both of y are more than 0.0000 and 0.0150 or less, The sintered compact according to any one of claims 4 to 6 characterized by things.