JPS62167218A - Production of zirconium oxide powder obtained from rare earth element formed solid solution - Google Patents

Abstract

PURPOSE:To produce zirconium oxide powder wherein homogeneous and fine rare earth element is formed solid solution by subjecting zirconium-rare earth element coprecipitation hydroxide to hydrothermal treatment and crystallizing it partially and lowering hydrothermal crystallization temp. CONSTITUTION:The following hydrated zirconium oxide powder is aged in the saturated steam atmosphere of 5-20kg/cm<2> in a hydrated state whose circumference is stuck with either zirconium-rare earth element coprecipitation hydroxide coprecipitated with rare earth element and zirconium or hydrated gelatinous unstable hydroxide of rare earth element. This aged material is roasted at 300-1,000 deg.C to produce zirconium oxide powder wherein rare earth element solid solution is formed.

Description

[Detailed Description of the Invention] Risen yo L Kuribu! The present invention relates to a new method for producing zirconium oxide containing a rare earth element as a solid solution, and uses a rare earth element that is homogeneous, fine, easy to sinter, and has physical properties suitable as a raw material for stabilized zirconia or partially stabilized zirconia. Solid-dissolved zirconium oxide powder! ! ! This is related to the delivery method.

Conventional technology Conventionally, zirconium oxide powder with a solid solution of rare earth elements used as a raw material for stabilized zirconia ceramics or partially stabilized zirconia ceramics is made by finely powdering rare earth raw materials such as zirconium oxide, hydrous acid oxides, or rare earth oxides. After mixing the powders, they are heated for a long time at a temperature of 1000℃ or higher in a high-temperature heating device such as an electric furnace or gas furnace, and the rare earth elements are diffused into the zirconia raw material powder through the contact surface of both raw material powders. It utilized a high-temperature diffusion reaction between solids and solids.

Rare earth element solid solution zirconium oxide powder obtained by such a solid + i reaction method not only takes time to manufacture, but also
During production, grain growth of zirconium oxide occurs, which increases the -order particle size and increases the aggregation between -order particles.
Therefore, in order to produce a sintered body using this, it is necessary to maintain the temperature several hundred degrees higher than when using the method of the present invention, and also, It had drawbacks such as low density and low strength.

In recent years, by adding a common precipitant to a mixed aqueous solution of a water-soluble zirconium salt and a water-soluble rare earth element salt, the zirconium compound and the rare earth element compound are simultaneously precipitated to create a fine powder mixture. Some coprecipitation methods have been put into practical use, in which the contact area between the zirconium oxide raw material powder and the rare earth oxide raw material powder is increased, and these are heated in a high-temperature heating device such as an electric furnace or a gas furnace.

Compared to the powder mixing method described above, this method requires a temperature several 100 degrees lower to dissolve rare earth elements into a solid solution, and can be said to be an excellent method. It still uses a heating diffusion reaction using a furnace, and as a result, the resulting powder has severe agglomeration between particles that occurs during heating, and this aggregation remains even if the powder is ground with a ball mill etc. Moreover, even if this powder was pressurized in a mold, it remained unbroken.

For this reason, the sintering temperature required to make a high-density sintered body using zirconium oxide powder containing a solid solution of rare earth elements produced by this method is such that the voids remaining inside the aggregated particles are removed from the outside of the sintered body. The temperature required to move it to , practically 140
This required a temperature of 0°C or higher.

Recently, as a method of reducing interparticle aggregation of zirconium oxide powder containing a rare earth element as a solid solution by the coprecipitation method, a mixed precipitate using yttrium as the rare earth element is heated to 230'C or higher in water and subjected to pressure heating treatment. things have been reported.

[Hydrothermal Chemical Laboratory Report VO1, 3, NO12, P5 (1
979)] The present inventors have been investigating the production of raw material powder for stabilized zirconia ceramics or partially stabilized zirconia ceramics on an industrial scale using the method reported herein, but this method has It was found that there were the following problems.

That is, what is obtained by pressurizing and heating a mixed precipitate of yttrium and zirconium at a temperature of 230° C. or higher and 300° C. or lower is a highly agglomerated lump that cannot be used as it is as a ceramic raw material powder. In other words, if the lumps are mechanically pulverized and used as ceramic raw material powder, they will easily break during sintering.

This is thought to be because the amorphous mixed precipitate was not completely crystallized as an oxide during the pressure and heat treatment, so some hydrous oxide remained in the product. In fact, when the resulting agglomerates are heated to 1300° C., a weight loss of 2 to 10 wlo is observed.

In order to completely crystallize the oxide, if the treatment is carried out under high pressure and high temperature (300°C or higher), the weight loss due to heating will be less, but the degree of aggregation of the product will become stronger, and the ceramic raw material As a result, it is no longer practical as a powder.

Furthermore, the temperature required for the above pressure and heat treatment is 2.
It is reported that the temperature is 30°C or higher, and 300°C or higher for complete crystallization. Considering industrial production equipment under this condition, the use of an autoclave with a vapor pressure of 25kmcm2 or higher is considered, which reduces production equipment costs, This requires an extremely complex production system, including security equipment and management personnel for safe work.

Problems to be Solved by the Invention In order to solve the above-mentioned drawbacks of the prior art, the present invention involves hydrothermally treating a mixed precipitate to partially crystallize it, and lowering the hydrothermal crystallization temperature to overcome the conventional techniques. The present invention aims to provide a practical method for producing homogeneous, fine, and easily sintered zirconium oxide powder containing a rare earth element, which has never been seen before.

Means for Solving the Problems The structure of the present invention for solving the above problems is based on a zirconium-rare earth element co-precipitated hydroxide in which a rare earth element and zirconium are co-precipitated, or a hydrated gel-like amorphous form of a rare earth element. Hydrous zirconium oxide powder with hydroxide attached to the surrounding area is 5 kg/Cm2 or more and 20 kmMcm2 in a hydrated state.
The method is to produce zirconium oxide powder containing rare earth elements as a solid solution by curing in the following saturated steam atmosphere and then roasting the cured material.

The details of the present invention will be described below.

Rare earth elements that can be used in the present invention include lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium,
They are lutetium and yttrium.

Zirconium co-precipitated with rare earth elements and zirconium
Rare earth element hydroxide is an aqueous solution of water-soluble salts of one or more rare earth elements selected from the above rare earth elements, and a water-soluble salt of zirconium such as zirconium oxychloride and zirconium nitrate. It is obtained by mixing an aqueous solution and acting on the mixture with an alkali such as ammonia or caustic soda. The method of reacting a mixed aqueous solution of a rare earth element and a water-soluble salt of zirconium with an alkali is not particularly limited; Alternatively, a water-soluble salt of a rare earth element and zirconium may be added to an aqueous alkali solution.

Hydrous gel-like amorphous hydroxide of rare earth elements is a mixture of an aqueous solution of water-soluble salts of one or more rare earth elements selected from the rare earth elements listed above and an alkaline aqueous solution such as ammonia or caustic soda. It is an amorphous material that retains a large amount of water and has a translucent paste-like appearance, and its chemical structure has not been fully analyzed. When adding an alkaline aqueous solution to the aqueous solution of the water-soluble salt of the rare earth element mentioned above, if the addition rate is slowed down, the amorphous basic salt of the rare earth element (Ln (OH) y X-nHz 0SLn: rare earth element, X: raw material Although the anionic component of the salt is also produced at the same time, the effects of the present invention do not change even with such a mixture.

The hydrous zirconium oxide powder used in the present invention is generally represented by the chemical formula ZrO2・n)-12Q, and when X-ray diffraction is performed, it does not show a strong diffraction peak and is almost amorphous. However, when dispersed in water, it does not form an amorphous dispersion in the form of a paste, but instead forms a slurry-like dispersion that maintains the particle shape. This is a type of material that is used in large quantities as a raw material for lead. An aqueous solution of a water-soluble salt of zirconium and an alkaline aqueous solution such as ammonia or caustic soda were rapidly mixed into what was described as hydrous zirconium oxide to cause crystallization. Although there is a translucent glue-like amorphous material, this material cannot be used in the present invention.

In carrying out the present invention, the method for producing hydrous acid or zirconium powder having a hydrous gel-like amorphous hydroxide of a rare earth element attached to its surroundings is not particularly limited; The hydroxide and the hydrous zirconium oxide powder may be mechanically kneaded by adding water if necessary, or the hydrous zirconium oxide powder may be dispersed in water, and the rare earth element may be mixed in the form of a hydrous gel in the dispersion. After the amorphous hydroxide is dispersed and mixed, the solid matter may be filtered off. Ori disperses hydrous zirconium oxide powder in water in which a water-soluble salt of a rare earth element is dissolved, and then adds an alkaline aqueous solution such as aqueous ammonia or caustic soda water to the mixture to form a hydrous gel-like mixture containing a rare earth element. The mixture may be stirred while precipitating the regular hydroxide.

In other words, the hydrated gel-like amorphous hydroxide of rare earth elements is a glue-like substance and has a strong adhesion force to other objects, so whether it is mechanical mixing or dispersion mixing in water, if stirring is sufficient, hydrated zirconium oxide powder It adheres evenly to the surface.

In the present invention, the water-containing state is a state in which structured water that constitutes the hydrothermally treated material and free water that does not participate in the structure are present in the hydrothermally treated material, and in practical terms, It may be a zirconium-rare earth element co-precipitated hydroxide, or a slurry as it is prepared as a precipitate of hydrous zirconium oxide to which a hydrogel amorphous hydroxide of a rare earth element is attached.

Further, it may be a cake obtained by filtering the precipitate using a conventional filtration operation such as a glass filter or a centor, or it may be a cake obtained by roughly washing the cake with water or the like.

The rare earth element oxide/zirconium oxide ratio of the rare earth element and zirconium oxide solid-dissolved with the rare earth element obtained in the present invention varies somewhat depending on the type of rare earth element used, but is approximately 25 to 30% at most in terms of oxide mole%. . The practical aim of the present invention is to obtain raw material powder for stabilized zirconia ceramic or partially stabilized zirconia ceramic,
In this sense, the above mole % may be blended at a maximum of about 12 to 15%.

The steam curing conditions necessary to carry out the present invention are 20 km
It is necessary to have a saturated steam atmosphere of less than cm2,
Particularly preferred is a water vapor pressure of 5 kg/Cm2 or more15
It is a saturated water vapor atmosphere of kmCm2. That is, when kept in a saturated steam atmosphere with a steam pressure of 20 k (1/Cm2 or more), the crystallization of zirconium oxide and the solid solution of rare earth elements in the zirconium oxide are complete, but the resulting product If the water vapor pressure is 25 ko/cm2 or more, it will not turn into powder unless it is strongly mechanically pulverized, and cannot be formed using normal ceramic forming methods, making it impractical. This is because the water vapor pressure is 5 km cm.
If the following saturated steam is used, the desired product can be produced, but the treatment requires a long time, specifically 40 hours or more, which is not a practical condition.

In the present invention, after the above-mentioned high-temperature and high-pressure steam curing, the cured material is roasted. This is done in order to completely crystallize the resulting cured product, since when high-temperature, high-pressure steam curing is performed under the above conditions, crystallization has not progressed sufficiently and some water content remains. . That is, a product cured in high-temperature, high-pressure steam under the conditions of the present invention and dried at 200°C for 20 hours is zirconium oxide in which rare earth elements are solidly dissolved according to analysis by X-ray diffraction;
Upon heat treatment at 0'C, a weight loss of 3-a wt% is observed. This is thought to be due to crystal water of unreacted hydrated zirconium oxide or structural water rather than water adsorbed on the solid surface.

As a means to completely crystallize this unreacted portion, increasing the saturated water vapor pressure used will increase the degree of aggregation of the curing agent.
The product becomes lumpy, making it impractical as a ceramic raw material powder. The present inventors added a roasting process using a heating furnace in order to completely crystallize this unreacted hydrous zirconium oxide.

As in the present invention, after high-temperature, high-pressure steam curing is performed to crystallize most of the crystallization, the remaining portion is crystallized by roasting, and the other is crystallized by only roasting. The state of agglomeration between secondary particles and secondary particles differs between the two, and when zirconium oxide powder containing a solid solution of rare earth elements produced by each method is pressed in a mold, a press-molded product is formed. have different densities. That is, the material of the present invention has a higher density. This is the eighth example described in the embodiment of the present invention.
As can be seen from the figures (a) and (b) and the void pattern diagram of the press-molded product in Fig. 10, the agglomeration of the powder produced by the method of the present invention is weak, making it difficult to apply mechanical pressure. This is because it has the property of easily deagglomerating and condensing.

When carrying out the present invention, the temperature at which the high-temperature, high-pressure steam cured product is roasted must be 300°C or higher, preferably 60°C or higher.
The temperature is preferably 0°C or higher and 1000°C or lower. 30
At temperatures below 0°C, crystallization does not occur; at temperatures below 600'C, it takes a long time, specifically 6 hours or more, for sufficient crystallization; and when roasted at temperatures above 1000°C, This is because some sintering between powders is observed during roasting, which is not a practical condition.

Example 1 0.2 each of zirconium oxychloride and zirconium nitrate
Mix 4.6 m of an aqueous solution with a concentration of M/Jj and 0.8 m of an aqueous solution of 1 to 3 m nitrate with a concentration of 0.1 M/m (in terms of yttrium oxide), stir for 30 minutes, and add 3 M to the mixed aqueous solution. 1.5 grams of ammonia water with a /R concentration was added at once, stirred roughly for 30 minutes, and then filtered through a G4 glass filter. also showed an amorphous diffraction pattern. Roughly each cake, 10! 1]/Cm2 for 4 hours. When the X-ray diffraction patterns of the obtained cakes were measured, they all had a cubic phase crystal structure. As an example of an X-ray diffraction pattern, FIG. 1 shows an X-ray diffraction chart when zirconium oxychloride is used as a raw material. Also, take a portion of each cake and heat it to 200℃.
After drying for 20 hours, the weight loss rates during roasting at 1300'C were measured and found to be 8% and 9%, respectively.

Furthermore, each cake cured in the above steam atmosphere was
It was roasted at 0°C for 2 hours.

The composition ratio of ittria and zirconia of each roasted product was determined by fluorescent X.
When measured using the line method, each Y 20 ] /
Expressed as the molar ratio of Z r O2, (0,08±0.0
01)/(0,92±0.002)
□It was.

In addition, when we measured the X-ray diffraction pattern of each roasted product,
All of them had a cubic-phase crystal structure, and there was no single peak of yttrium oxide that was not solidly dissolved in the zirconium oxide, indicating that a uniform solid solution had been achieved.

As an example, FIG. 2 shows an X-ray diffraction chart when zirconium oxychloride is used as a starting material.

Furthermore, when the weight loss rate of each roasted product was measured during roasting at 1300°C, it was 2% or less in all cases.

In addition, each of the above-mentioned roasted products was molded into pellets with a diameter of 20 mm and a thickness of 2 mm (-shaft, pressure 1.5 tbcm2) L/
When sintered in air at 1300° C. for 3 hours, all were densified to 95% or more of the theoretical density.

Example 2 0.2M/1 aqueous solution of zirconium oxychloride 4.6
and 0.0% each of yttrium acetate and iso1-lium chloride.
1M/exchange concentration (yttrium oxide equivalent) aqueous solution 0.8
After stirring for 30 minutes, a coprecipitate was prepared, cured in saturated steam, and roasted in the same manner as in Example 1. The powders obtained were equivalent to those obtained in Example 1 in terms of composition, structure, and sinterability.

Example 3 Solution of 3M 15I concentration of zirconium oxychloride 3.0
A 0.4M aqueous solution of yttrium nitrate with a concentration of 2M/9 (in terms of yttrium oxide) was mixed with the mixture, stirred for 30 minutes, and the mixed aqueous solution was dropped over 4 hours into 5 volumes of aqueous ammonia with a concentration of 3M and 15I. After the dropwise addition, stirring was continued for 30 minutes, and the mixture was filtered using a G4 glass filter.

The obtained precipitate was washed with water in an amount of 10 (8) of the precipitation volume.

The pH after washing with water was 9.3. The precipitate was cured in saturated steam and roasted in the same manner as in Example 1. The obtained powder was equivalent to that obtained in Example 1 in both its composition and structure. Further, when a sinterability test was conducted in the same manner as in Example 1, the material was densified to 97% of the theoretical density.

Example 4 Zirconium oxychloride 3M/9. Solution of concentration 3.0
67 ml and 0.4 ml of an aqueous solution of 2M/exchange concentration (in terms of yttrium oxide) of yttrium nitrate were mixed, stirred for 30 minutes, and the mixed aqueous solution was placed in a 6M/M concentration caustic soda solution 1052 kept at 90°C. The mixture was added dropwise over 4 hours. After the dropwise addition, stirring was continued for 30 minutes, and the mixture was filtered through a G4 glass filter. The obtained precipitate was washed with water 20 times the volume of the precipitate. The precipitate was cured in saturated steam and roasted in the same manner as in Example 1. The obtained powder was equivalent to that obtained in Example 1 in terms of composition, structure, and sinterability.

Example 5 The zirconium-yttrium co-washed product prepared in the same manner as in Example 3 was divided into 12 equal parts, and each part was cured in a saturated steam atmosphere under the following conditions.

b) Water vapor pressure 2kg/cm2.4 hours) rt 4kMccm2, 〃c) n
5kg/cm2, 〃2) 710kg70m2.2 hours e) Water vapor pressure 10kmcm2.4 hours) 〃 〃 , 8 hours g) tt 16kg/cm', 2 hours h)
〃 〃 , 4 hours wa) 〃 〃 , 8 hours nu) /l 20kmcm2.4 hours ru) /
I 25kMCm2, 〃wo) n 30k
g/cm2, II Take a certain amount of each cultured organism, and
After drying for Cl2O hours, the weight loss rate during roasting at 1300°C was measured.

Each culture was also roasted at 750'C for 2 hours.

After roasting, the products under conditions a) to n) became powders with weak aggregation, but the products under conditions a) and wo) became highly agglomerated lumps. Roughly, each roasted product was ground in a mortar for 30 minutes for those under the conditions [l) and [wo]], and then sintered in the same manner as in Example 1. Sintered body density and the above 200
Table 1 shows the weight loss rate when the powder was roasted at 1300'C after drying and roasting.

Table 1 Example 6 Solution of 3M/M concentration of zirconium oxychloride 3.06
79. and 0.4 R of each 2 M/1) aqueous solution of neodymium nitrate, dysprosium nitrate, and gadolinium nitrate, stirred for 30 minutes, and kept the mixed aqueous solution at 90'C. /U concentration of caustic soda solution 10
9. It was dripped into the inside over 4 hours. After the dropwise addition, stirring was continued for 30 minutes, and the mixture was filtered through a G4 glass filter.

After washing the obtained precipitate with water 10 times the volume of the precipitate,
Curing in saturated steam and roasting were performed in the same manner as in Example 1. The obtained powder was subjected to N
When the molar ratios of d2C)+/ZrO2, D'/20x/ZrO2, and Qd203/ZrO2 were measured, they were all (0,08±0.002)/(0,92
±0.002).

In addition, when we measured the X-ray diffraction pattern of each roasted product,
All exhibited a cubic-phase crystal structure. As an example, roasted product X made using dysprosium nitrate as a starting material
A line diffraction chart is shown in FIG.

In addition, each of the above-mentioned roasted products was molded in the same manner as in Example 1, and
When sintered at 0'C for 3 hours, both had a theoretical density of 9.
It was densified to 6% or more.

Example 8 A] Production of gel amorphous yttrium hydroxide.

Yttrium chloride, yttrium nitrate, yttrium acetate each 0.1M/9. Add 0.9 M of ammonia water with a concentration of 3 M/ml at once to 8 parts of aqueous solution with a concentration (in terms of yttrium oxide), stir at room temperature for 30 minutes, and filter each gel-like substance formed using a G3 glass filter. did. When a portion of each gel material was taken out, washed with water, and subjected to X-ray diffraction measurement, the results of each gel material were as shown in the chart shown in FIG. Further, a portion of each gel-like material was washed with water and then vacuum-dried at room temperature, and the infrared absorption spectra of each were measured, and the results were as shown in the chart shown in FIG. 5 for each gel-like material.

In addition, after washing a portion of each gel with water, it was dissolved in dilute sulfuric acid, and ammonia ions, chloride ions, nitrate ions, and acetate ions in the solution were determined by a conventional method. was not observed.

B] Adhesion of gelled ice yttrium hydroxide to the surface of hydrated zirconium oxide powder.

Each of the above-mentioned gel-like substances was added to four volumes of water and stirred to prepare a suspension of the gel-like substances. When stirring of the suspension was stopped and left for one day and night, each gel-like substance slightly settled,
The sedimentation volume was approximately 3.5 for each. 9. While stirring the mixture again, add the hydrous zirconium oxide powder to the mixture.
2 mol (3.12 kg>) was added, stirring was stopped after 10 minutes, and the mixture was allowed to stand for 2 hours. In both cases, solid matter settled at the bottom of the container, and the top was covered with a clear liquid. Solid matter settled at the bottom. The volume of both combined liquids was approximately 3 mon.

Solid matter was separated from the above mixture using a 04 glass filter.

C] Curing in a saturated steam atmosphere Each of the above cakes was cured for 4 hours in a saturated steam atmosphere of 10 kg/Cml. When the X-ray diffraction patterns of the resulting cakes were measured, they all had a cubic-phase crystal structure. After drying a portion of each cake at 200°C for 20 hours, we measured the weight loss rate when roasting at 1300°C.
All were in the range of 5-10%. As an example of an X-ray diffraction pattern, FIG. 6 shows an X-ray diffraction chart when yttrium nitrate is used as a raw material.

D] Roasting for crystallization Each cake cured in a saturated steam atmosphere was heated to 750
Roasted at 'C for 2 hours.

When the composition ratio of yttrium and zirconia of each roasted product was measured by fluorescent X-ray method, each of them was found to be Y 20 ] /
Expressed as molar ratio of Z r O2 (0,08±0.0
01)/(0,92±0.002).

In addition, when we measured the X-ray diffraction pattern of each roasted product,
It was found that all of them had a cubic-phase crystal structure, and a uniform solid solution was achieved. As an example of the X-ray diffraction pattern of a roasted product, when yttrium nitrate is used as a raw material,
A line diffraction chart is shown in FIG.

Furthermore, when the weight loss rate of each roasted product was measured during roasting at 1300'C, it was 2% or less in all cases.

In addition, when each of the above-mentioned roasted products was molded into pellets with a diameter of 20 mm and a thickness of 2 mm and sintered with a mold (-axis) at a pressure of 1.5 tb, each pellet was densified to 97% or more of the theoretical density.

Example 9 Aqueous solution of yttrium chloride in O, 7 M/U concentration 89. A gel-like material similar to that in Example 8 was prepared by adding 0.9 M of caustic soda water having a concentration of 3 M/R into the solution at once. The composition and structure of the gel-like material were measured in the same manner as in Example 8, and it was found that it was the same as the gel-like amorphous yttrium hydroxide produced in Example 8. Using this gel material, it was adhered to hydrous zirconium oxide in the same manner as in Example 8, cured in a saturated steam atmosphere (10 kg/cm'', 4 hours), and roasted (750° C., 12 hours). The resulting powder was equivalent to that produced in Example 8 in terms of composition, structure, and sinterability.

Example 10 9.2 moles of the same hydrated zirconium oxide powder used in Example 8 was added to 8 volumes of an aqueous solution of yttrium chloride with a concentration of 0.1 M 15I (in terms of yttrium oxide) (in terms of zirconium oxide, 3.12 kO of hydrated zirconium oxide). ) plus,
Stirring was performed to create a uniform suspension. In the suspension, 3
0.91 of M/1 concentration ammonia water was added at once, stirring was continued for 30 minutes, and then left for 2 hours.

A white solid was precipitated at the bottom of the container, and the settled volume was 3 mon. The upper part was a transparent liquid, and when the concentration of yttrium in the liquid was measured using a conventional method, no yttrium was detected.

The obtained precipitate was filtered through a No. 04 glass filter, and cured in saturated steam (10 kmM) in the same manner as in Example 8.
cm2.4 hours) and roasting (750°C, 2 hours). The obtained powder was equivalent to that made in Example 8 in terms of composition, structure, and sinterability.

Example 11 9 moles of ammonia water with a concentration of 0.3 M/liter and 9.2 moles (3 moles) of the same hydrous zirconium oxide powder used in Example 8.
, 12k(J) and 0.2M while stirring.
Add 4 liters of yttrium chloride aqueous solution at a concentration of 10
Stirring was stopped after a minute. After standing for 2 hours, the yttrium concentration in the supernatant was measured, and no yttrium was detected.

After filtering the solid content obtained above, curing in saturated steam (10 kmcm', 4 hours) in the same manner as in Example 1,
and roasting (750'C, 12 hours). The composition, structure, and sinterability of the obtained powder were measured in the same manner as in Example 8, and it was found to be equivalent to that produced in Example 1.

Example 12 In three portions of an aqueous solution of yttrium nitrate at a concentration of 0.1 M/1 (in terms of yttrium oxide), 9.7 moles of the same hydrous zirconium oxide as used in Example 8 (in terms of zirconium oxide, 3.30 kg of hydrous zirconium oxide) > was added and stirred to make a homogeneous suspension.Into the suspension, 3M1
0.451 ml of aqueous ammonia at 511 degrees Celsius was added at once, stirring was continued for 30 minutes, and the mixture was filtered using a G4 glass filter. The resulting cake was divided into 12 equal parts, each of which was cured in a saturated steam atmosphere under the following conditions.

A〉Water vapor pressure 2kMcm', 4 hours) rt 4kg/cm2,〃C) u
5kMccm', 〃 2) tt 10kMccm2.2 hours e) //
〃, to 4 hours) tt u, to 3 hours) tt
16kg/cm2.2 hours) II
II, 4 hours) rt rt
, 3 hours) tt 20kg/cm2.4 hours) tt 25kMccm2, //wo)
rt 30kg/cm2, ? ll Cultivation organism constant m
After drying at 200°C for 20 hours, the weight loss rate during roasting at 1300'C was measured.

Each culture was also roasted at 750″C for 2 hours.

After roasting or drying, the powders under conditions a) to n) became weakly agglomerated powders, but those under conditions a) and wo) became highly agglomerated lumps.

Roughly, after grinding each roasted product in a mortar for 30 minutes for those under the conditions [ru), wo)], diameter 20 mm, thickness 2
Mold molding into mm pellets (-axis, pressure 1.5t)
sintered in air for 1 h. Sintered body density and the above 20
After drying at 0°C, the roasted powder was roasted at 1300'C, and the weight loss rate was as shown in Table 2.

In addition, curing in a saturated steam atmosphere under the conditions of 2) and e),
Materials roasted at 750℃ for 2 hours are molded into molds (-
The void pattern of the molded body was measured using a mercury intrusion porosimeter. The results are shown in FIGS. 8a) and b), respectively.

Table 2 Example 13 The same hydrous zirconium oxide used in Example 8 was added to 3 aqueous solutions of neodymium nitrate, diplodium nitrate, and gadolinium nitrate each at a concentration of 0.1 M/R (in oxide terms).
7 mol (calculated as zirconium oxide, 3.30 klll of hydrous zirconium oxide) was added and stirred to form a uniform suspension. To the suspension, 0.1H1 of 3MZxm degree ammonia water was added at once, stirring was continued for 30 minutes, and then filtered using a G4 glass filter. Each cake obtained was heated in a saturated steam atmosphere of 10 kMCm2,
It was cured for 4 hours. After roasting the obtained cured material at 750°C for 2 hours, Nd20x/ZrO2,
D'l/203/ZrO2, G d 20 :l/
When the molar ratio of Z r 02 was measured, all (0,0
3±0.001)/(0.97±0.002).

In addition, when we measured the X-ray diffraction pattern of each roasted product,
All exhibited a tetragonal-phase crystal structure. As an example, FIG. 9 shows an X-ray diffraction chart of a roasted product prepared using dysprosium nitrate as a starting material.

Roughly mold each roasted product in the same manner as in Example 8, and
When sintered at 0°C for 3 hours, the theoretical density was 97.
% or more.

Example 14 9.2 moles of the same hydrous zirconium oxide as used in Example 8 (in terms of zirconium oxide, 3.0 moles of hydrous zirconium oxide) was added to an aqueous solution of 0.1 M yttrium nitrate/concentration (in terms of yttrium oxide). 12 kg> was added and stirred to make a homogeneous suspension.To the suspension, 0.95.
After continuing for 0 minutes, it was filtered using a G4 glass filter. The resulting cake was cured for 4 hours in a saturated steam atmosphere of 10 kMCI2. The obtained cured product was divided into 8 parts and roasted under the following conditions.

a) 300℃, 4 hours) 500℃, C) , 6 hours 2〉, 10 hours e) 600℃, 2 hours) 800℃, g) 1ooo℃, 〃 H) 1100'C, 〃 The above-mentioned roasted product was roasted at 1300°C, the weight loss rate was measured, and molded in the same manner as in Example 8.
Time sintering was performed. Table 3 shows the weight reduction rate and the sintered body density. Regarding c), 4 out of 5 molded bodies were broken. It was attached to zirconium oxide powder in the same manner as in Example 1 so that the following composition ratio was achieved.

(a) Y203/ZrO2 (molar ratio) = 3/97 (b) = 16/84 (c) = 32/68 (d)
It = 40/60 Each sample was cured in a saturated steam atmosphere (10 kg/Cm 2.4 hours) and roasted (75
0°C for 2 hours).

When the obtained powders were subjected to X-ray diffraction, (a), (
In both cases (b) and (c), there was no undissolved yttrium oxide, and in (a) the crystal structure was a tetragonal phase (b), and in (c) the crystal structure was a cubic phase.

In the case of (d), a single peak of yttrium oxide, which was not dissolved in solid solution, was observed.

A certain amount of the roasted product of (d) was collected, a certain amount of bismuth oxide was added as an internal standard, and an X-ray diffraction chart of the mixed sample was created and the height of the diffraction peak of the (222) plane of yttrium oxide and bismuth oxide were obtained. The amount of undissolved yttrium oxide present in each sample was approximately measured by a method of measuring the height ratio of the diffraction peaks of the (121) plane, and the amount of undissolved yttrium oxide was 5 wt%.

Comparative Example 1 Zirconium oxychloride 0.2M/9. s degree aqueous solution and 0.1 M/cross concentration of yttrium nitrate (
1 yen! (in terms of yttrium dioxide) and stirred for 30 minutes. To the mixed aqueous solution, 1.5 grams of ammonia water with a concentration of 3M15I was added at once, and after roughly stirring for 30 minutes, a G4 glass filter was mixed. It was filtered. The resulting cake was translucent and glue-like, and no peaks were observed in the X-ray diffraction pattern. The above cake was divided into four parts and each part was cured in a saturated steam atmosphere under the following conditions.

b) Water vapor pressure 20kg/cm2.4 hours) n
30kg/cm2, 〃c) // 3
5kMCm2, 〃2) Water vapor pressure 40kMCm2.4
After curing for an hour, each cured product was dried at 200° C. for 20 hours. After drying, the nutrient solution formed into highly agglomerated lumps.

After pulverizing the dried material in a mortar for 30 minutes, the weight loss rate when roasted at 1300°C and the density when sintered at 1300''C were measured in the same manner as in Example 1, and the results were as shown in Table 4. .

In addition, as for the molded products (1), 4 out of 5 molded products were broken during sintering.

Table 4 Comparative Example 2 Aqueous solution of yttrium nitrate with 0.1M15I concentration (calculated as yttrium oxide) 39. 9.7 mol of hydrous zirconium oxide (3.30 klj of hydrous zirconium oxide, calculated as zirconium oxide), which was the same as that used in Example 8, was added thereto and stirred to form a uniform suspension. Into the suspension, add 0.41 ammonia water with a concentration of 3M/millimeter at a time,
After stirring for 30 minutes, the mixture was filtered using a G4 glass filter. The resulting cake was roasted at 750° C. for 2 hours, molded in the same manner as in Example 8, and the void pattern in the molded body was measured in the same manner as in Example 5. The results are shown in FIG. In addition, the molded body was heated at 1300'C and 1
After sintering at 400'C for 3 hours and measuring the density,
They were densified to 90% and 98% of their theoretical densities, respectively.

Comparative Example 3 In three portions of an aqueous solution of 0.1 M/exchange concentration (in terms of yttrium oxide) of yttrium nitrate, 9.7 moles of hydrous fermented zirconium (in terms of zirconium oxide), the same as that used in Example 8, was added (in terms of zirconium oxide). 30k (It) was added and stirred to make a homogeneous suspension.To the suspension, 0.4R of ammonia water with a concentration of 3M/R was added at once, and stirring was continued for 30 minutes. It was filtered using a G4 glass filter.The resulting cake was dried at 150'C for 14 hours, cured for 4 hours in a saturated steam atmosphere of 10 kg/am2, and then roasted at 750°C for 2 hours.

The roasted product was molded into pellets with a diameter of 20 mm and a thickness of 2 mm in the same manner as in Example 8, and sintered in air at 1300° C. for 3 hours. The density of the sintered body was 94% of the theoretical density.

[Brief explanation of drawings]

Figure 1 is the X-ray diffraction chart of the cured product in Example 1 when zirconium oxychloride was used as the raw material. Figure 2 is the X-ray diffraction chart of the cured product in Example 1 when zirconium oxychloride was used as the raw material Ray diffraction chart. Figure 3 is an X-ray diffraction chart of the product roasted at 750°C when dysprosium nitrate was used as a raw material in Example 6. Figure 4 is an X-ray diffraction chart of gelled amorphous yttrium hydroxide. Chart, Figure 5 is the infrared absorption spectrum of gel-like amorphous yttrium hydroxide after vacuum drying at room temperature, Figure 6 is the X-ray diffraction of the cured product in Example 8 when yttrium nitrate was used as the raw material. Chart, Figure 7 is an X-ray diffraction chart of the roasted product at 750°C when yttrium nitrate was used as the raw material in Example 8, Figure 8(a) is the powder prepared under the conditions of 2) in Example 12. Molding the body with a mold (-axis, 1.5 ton/cm2)
Figure 8(b) shows the void pattern of the molded body when L/L.
Figure 9 is an X-ray diffraction chart of the roasted product obtained by using dysprosium nitrate as the starting material in Example 13. This is the void pattern of the molded product when the pottery is molded with a mold (-axis, pressure 1.5 ton/cm') L/L. Patent Applicant Asahi Kasei Industries Co., Ltd. Agent Patent Attorney Hide Komatsu Agent Patent Attorney Hiroo Asahi 6 Figure 25 3D3540 45 (2θ) Off Figure 25 JOJS 40 45 (2θ) Worlds￥Ho Tense Rei F2g g g Sa 3 f- also seven tans

Claims (1)

[Claims] A zirconium-rare earth element co-precipitated hydroxide in which a rare earth element and zirconium are co-precipitated, or a hydrated zirconium oxide powder with a hydrous gel-like amorphous hydroxide of a rare earth element attached to its surroundings, in a hydrated state. ,5kg/cm^2
As described above, the method for producing zirconium oxide powder containing rare earth elements as a solid solution is characterized by curing in a saturated steam atmosphere of 20 kg/cm^2 or less, and then roasting the cured material.