JPH06157037A - Manufacturing method of zirconium oxide powder - Google Patents

Abstract

PURPOSE:To provide highly pure zirconium oxide powder uniformly controlled in its composition and in its particle diameters and excellent in dispersibility. CONSTITUTION:The aqueous solution of a zirconium salt containing zirconium oxide hydrate, the aqueous solution of a stabilizer precursor, and an alkali aqueous solution are fed into a reaction tank, and brought into contact with each other, while maintaining the pH of the solution in the reaction tank at a substantially constant value. The produced precipitates are separated, dried and calcined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-purity zirconium oxide powder having a composition and a particle size which are uniformly controlled and excellent in dispersibility.

Zirconium oxide powder is used as a material for weak electricity, an optical lens, a sintered body for forming a thin film, a special refractory material, a toughness-reinforced material and the like.

The zirconium oxide powder used for these purposes has a uniform composition, a fine powder size, a uniform particle size, and good particle dispersibility. Various characteristics such as high purity are required.

[0004]

2. Description of the Related Art As a method for producing zirconium oxide powder having a relatively uniform particle size distribution, or as a method expected to be effective, a reaction tank provided with a liquid adjusted to a predetermined pH value. A zirconium salt and a mixed aqueous solution containing at least one of water-soluble salts of yttrium, calcium, and magnesium and an alkaline aqueous solution such as ammonia water are separately quantitatively sent to each other, and the pH in the reaction tank is kept within a certain range. And a reaction product solution containing the precipitate so that the amount of liquid in the reaction vessel is constant. It is proposed that the method is performed continuously while flowing out the water (Japanese Patent Publication No. 2-35694).

[0005]

However, the present inventors have made the composition and particle size distribution of the zirconium oxide powder uniform by only adjusting the pH of the liquid in the reaction tank and the flow rate of the liquid supplied. However, it has been found that there is room to further improve the purity of the powder.

The present invention solves the above problems,
That is, it is an object of the present invention to provide a method for obtaining a highly pure zirconium oxide powder having a composition and a particle size controlled more uniformly and excellent dispersibility.

[0007]

The present inventors have found that the above target fine powder can be obtained by carrying out the neutralization precipitation forming reaction in the presence of hydrated zirconium oxide while keeping the pH constant. The present invention has been completed.

That is, according to the present invention, an aqueous solution of a zirconium salt containing hydrated zirconium oxide, a stabilizer precursor aqueous solution and an alkaline aqueous solution are respectively supplied to a reaction vessel, and the pH of the solution in the reaction vessel is kept substantially constant. The gist of the present invention is a process for producing a zirconium oxide powder, which comprises contacting these while maintaining the values, separating the obtained precipitate, drying and firing.

In the present specification, the "stabilizer precursor" means a water-soluble salt which becomes a stabilizer of zirconium oxide by firing, and the "stabilizer precursor aqueous solution" means its aqueous solution.

The present invention will be described in more detail below.

As the stabilizer precursor, yttrium,
Examples thereof include rare earth elements such as cerium, lanthanum and ytterbium, and chlorides such as group IIa elements such as calcium and magnesium, and water-soluble salts such as sulfates and nitrates.

As the hydrated zirconium oxide, both amorphous hydrated zirconium oxide and crystalline hydrated zirconium oxide can be used. The crystalline hydrated zirconium oxide is preferably a highly pure and highly crystalline one obtained by a thermal hydrolysis method, for example, a ZrO ₂ concentration of 0.2 mol / mol.
It is obtained by boiling liter of zirconium oxychloride for 80 hours. Further, as the alkaline aqueous solution, an aqueous solution of ammonia, sodium hydroxide, potassium hydroxide or the like can be used.

The reaction according to the present invention can be carried out batchwise or continuously, but from the industrial and economical viewpoint, the continuous reaction is preferred. Also, there is no particular restriction on the type of reaction tank, but as the precipitate concentration increases, the viscosity of the reaction solution increases, so a reaction tank equipped with a stirrer can be used to keep the mixed state uniform. preferable.

The reaction operation method may be any method as long as the pH of the reaction system is maintained at a substantially constant value, but the method described below facilitates the adjustment of the pH. . That is, first, before starting the reaction, water adjusted in advance to the same pH as the pH of the liquid after the reaction is prepared is prepared in the reaction tank. As this water, if a hydrated zirconium oxide suspension having a concentration within a range not exceeding the final ultimate concentration of a predetermined formed precipitate is prepared in the reaction tank in advance, the effect will be better exhibited as described below. It To the water thus prepared, a zirconium salt aqueous solution containing hydrated zirconium oxide, a stabilizer precursor aqueous solution and an alkaline aqueous solution are simultaneously supplied so that a predetermined pH and composition are maintained.
Although these can be supplied separately, a liquid consisting of the former two, that is, a hydrated zirconium oxide suspension and a liquid in which a zirconium salt and a stabilizer precursor are dissolved, and an alkaline aqueous solution are supplied. By adopting such a form, it is possible to mix more uniformly in the reaction tank. The pH and composition of the product liquid in the reaction tank can be maintained at constant values by supplying each of them at a constant concentration and a constant composition and at a constant flow rate ratio. In the continuous operation, the product liquid is continuously withdrawn by a metering pump, an overflow system or the like so that the liquid amount becomes constant in the reaction tank.
In the case of batch operation, the supply of the raw material liquid is stopped when the liquid in the reaction tank reaches a predetermined amount.

By separating the precipitate from the reaction solution thus obtained, washing, drying and baking, the composition and particle size distribution are uniformly controlled, and the cations and anions excellent in dispersibility are obtained. A high-concentration zirconium oxide powder containing no impurities is obtained. In addition, since the hydrated zirconium oxide is contained in the aqueous solution of the zirconium salt as a raw material in advance, the pH of the system fluctuates due to a slight imbalance in the flow rate which tends to occur immediately after the reaction starts (immediately after the solution addition starts). Alternatively, it plays a buffering role against the increase in viscosity in the reaction tank, the pH is maintained substantially constant from the start of the reaction, and a uniform mixed state is always maintained, whereby the composition and particle size become uniform. A high-purity fine zirconium oxide powder having a controlled and excellent dispersibility can be obtained. The particle size of this powder can be measured by a centrifugal sedimentation type particle size distribution measuring device or the like, and the dispersibility can be judged by observing an electron micrograph or the like. According to an example of the sample obtained according to the present invention, the one obtained by firing at 850 ° C. is 0.10
95% or more of particles having a particle size range of up to 1.00 μm
Also, the spherical particles are in a state of being dispersed almost one by one.

The precipitate in the product solution is filtered, washed with water, dehydrated and dried, and calcined at a temperature of 500 to 1300 ° C. to obtain a fine powder.

Further, a predetermined p prepared in advance in the reaction tank is used.
The amount of H water is not particularly limited as long as stirring is possible. The water having a predetermined pH prepared in advance in the reaction tank may be adjusted by adding an alkaline substance to the water to adjust the pH to that in the main operation. When hydrated zirconium oxide is also added to this water, the pH of the water to which the hydrated zirconium oxide is added may be too high. In such a case, it is necessary to adjust the pH with an acidic substance.

The hydrated zirconium oxide in the aqueous solution of zirconium salt (in the mixed aqueous solution of the zirconium salt and the stabilizer precursor, if included) is Z
It may be 1% or more in terms of r, and the upper limit may be determined in consideration of productivity. If the content is lower than 1%, the buffering effect is low, and therefore the pH uniformity of the reaction system is poor.
The resulting zirconium oxide powder tends to have low composition and particle size uniformity and purity.

The final concentration of the produced precipitate is not particularly limited, but in order to obtain a fine powder of high purity whose composition and particle size are uniformly controlled and which is excellent in dispersibility, it is 10 in terms of ZrO _2. The range of up to 300 g / liter is preferred. 10 g /
When the concentration is lower than 1 liter, it is difficult to remove water and the like in the dried precipitate, which is considered to be the cause. However, the powder after calcination has a non-uniform composition and particle size, and has poor dispersibility and purity. If it exceeds 300 g / liter, the resulting liquid has a high viscosity and poor fluidity, and it becomes difficult to obtain a powder having a uniform composition and particle size, good dispersibility, and high purity.

The pH is preferably selected from the range of 7 to 13 from the precipitation forming region of the target precipitation product. When the pH is lower than 7, the purpose, that is, the composition and the particle size are uniform,
It is difficult to obtain a powder having good dispersibility and high purity, and when it exceeds 13, it becomes difficult to remove water, impurities and the like from the precipitate, which is considered to be the cause, but the composition and particle size are uniform. However, it becomes difficult to obtain fine powder having good dispersibility and high purity.

[0021]

In the conventional method in which the pH of the reaction solution and the supply flow rate of the raw material solution are constant, the reaction between the zirconium salt and the alkaline aqueous solution is locally carried out in the reaction tank when the precipitate concentration is low immediately after the start of the reaction. Not only the composition and particle size become non-uniform, but also the agglomeration becomes vigorous, and during the agglomeration, the impurity anions and cations in the liquid are taken into the agglomerate, and the resulting oxidation occurs. The purity of zirconium powder deteriorates.

In the present invention, since hydrated zirconium oxide is contained in the aqueous solution of zirconium salt, it is presumed that all the drawbacks of the above conventional method can be solved.

[0023]

As is apparent from the above description, according to the present invention, it is possible to obtain a high-purity zirconium oxide powder whose composition and particle size are uniformly controlled and which is excellent in particle dispersibility.

[0024]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 Into a reaction tank having a volume of 5 liters up to an overflow outflow pipe, 2 liters of water whose pH was adjusted to 9 with ammonia water was put and stirred. 42 ml / min of a mixed aqueous solution of 1.54 mol / liter of zirconium oxychloride containing 10% of the total Zr amount as crystalline hydrated zirconium oxide and 0.10 mol / liter of yttrium chloride was placed in the reaction tank under water stirring. At flow rate and concentration 9.1 wt
% Aqueous ammonia at a flow rate of 42 ml / min at the same time by a constant flow pump, and the reaction solution is flowed out from the overflow pipe at a flow rate of 84 ml / min in terms of the raw material solution to continuously produce a neutralized precipitate. The reaction was run for 2.6 hours. The liquid in the reaction tank was maintained at pH 9. Separate the precipitate in the overflow effluent,
Impurities were removed by washing with water. Immediately after the start of the reaction operation, immediately before the end of the reaction operation, and at equal intervals during the reaction operation time, a total of 5 samples of precipitates were sampled at 110 ° C. for 2 times each.
After drying for 4 hours, it is baked at 800 ° C. for 1 hour, and the average particle size is 0.53 to 0.6 by a centrifugal sedimentation type particle size distribution measuring device.
4 μm, particle size range of 0.10 to 1.00 μm, 90 to 94%, and particle size distribution width of 0.10 to 2.
00 μm, specific surface area is 21 m ² / g and Zr
The purity of O ₂ + Y ₂ O ₃ is 99.9 wt% or more, Y ₂
3 mol% of O ₃ / (ZrO ₂ + Y ₂ O ₃ ) yttria partially stabilized zirconium oxide fine powder was obtained.

Example 2 2 liters of water adjusted to pH 12 with aqueous ammonia was placed in a reaction tank and stirred. 42 ml / min of a mixed aqueous solution of 0.78 mol / liter of zirconium oxychloride containing 10% of the total Zr amount as crystalline hydrated zirconium oxide and 0.07 mol / liter of calcium chloride was placed in the reaction tank under water stirring. At flow rate and concentration 10.
At the same time, 2 wt% ammonia water was started to be supplied at a flow rate of 42 ml / min by a constant flow pump, and a neutralization precipitation forming reaction was carried out for 0.6 hours by a batch reaction system. The pH of the liquid in the reaction tank was maintained at 12. The formed precipitate was separated and washed with water to remove impurities. Immediately after the start of the reaction operation, immediately before the end of the reaction operation, and at equidistant intervals during the reaction operation time, the three samples of the precipitates in the reaction vessel at a total of 5 points were dried at 110 ° C. for 24 hours and then calcined at 700 ° C. for 1 hour. Then, the average particle size measured by the centrifugal sedimentation type particle size distribution measuring device is 0.
42 to 0.60 μm, particle size range 0.10 to 1.00 μm
In the range of 92 to 95%, the particle size distribution width is 0.10 to 2.00 μm, and the specific surface area is 27 m ² /
The purity of g and ZrO ₂ + CaO are both 99.9.
wt% or more, CaO / (ZrO ₂ + CaO) 8 mol%
A calcia partially stabilized zirconium oxide fine powder was obtained.

Example 3 Into a reaction tank having a volume of 5 liters up to an overflow outflow pipe, 2 waters adjusted to pH 11 with an aqueous NaOH solution were added.
1 liter was added and stirred. In this reaction tank under water stirring,
A mixed aqueous solution of 1.60 mol / liter of zirconium oxychloride containing 90% of the total Zr amount as crystalline hydrated zirconium oxide and 0.08 mol / liter of magnesium chloride at a flow rate of 42 ml / min and a concentration of 3.5 m.
At the same time, supply of ol / l NaOH aqueous solution at a flow rate of 42 ml / min was started by a constant flow pump, and the reaction liquid was supplied from the overflow pipe at 84 ml / min as a raw material solution conversion value.
The neutralization precipitation formation reaction was continuously carried out for 4.6 hours by an overflow method of flowing out at a ratio of. The pH of the liquid in the reaction tank was maintained at 11. The precipitate in the overflow effluent was separated and washed with water to remove impurities. Immediately after the start of the reaction operation, immediately before the end of the reaction operation, and at three points at equal intervals during the reaction operation time, a total of 5 samples of the precipitates were dried at 110 ° C. for 24 hours, then calcined at 850 ° C. for 1 hour, and centrifuged. Average particle size of 0.30 to 0.42 μm by sedimentation type particle size distribution measuring device, particle size range of 0.10 to 1.0
94 to 98% in the range of 0 μm, particle size distribution width of 0.10 to 2.00 μm, specific surface area of 32 m
The purity of ² / g and ZrO ₂ + MgO are both 9
9.9 wt% or more, MgO / (ZrO ₂ + MgO) is 5
A mol% magnesia partially stabilized zirconium oxide fine powder was obtained.

Example 4 2 liters of water adjusted to pH 9 with an aqueous NaOH solution was placed in a reaction vessel having a volume of 5 liters up to an overflow outflow tube and stirred. A crystalline hydrated zirconium oxide sol having a concentration of 0.8 mol / liter and a hydrolysis reaction rate of 96%, that is, 0.032 mol / l of zirconium oxychloride and a crystalline hydrated zirconium oxide sol in a concentration of 0.8 mol / liter was added to the reaction tank under water stirring. A mixed aqueous solution of 768 mol / liter and yttrium chloride 0.14 mol / liter was applied at a flow rate of 42 ml / min and a concentration of 1.9 mol.
/ Liter NaOH aqueous solution at a flow rate of 42 ml / min at the same time with a constant flow pump to start the supply, and the reaction solution is flown out at a rate of 84 ml / min in terms of raw material solution continuously by an overflow method for neutralization and precipitation. The production reaction was carried out for 2.6 hours. The liquid in the reaction tank is
The pH was maintained at 9. The precipitate in the overflow effluent was separated and washed with water to remove impurities. Immediately after the start of the reaction operation, immediately before the end of the reaction operation, and at three points at equal intervals during the reaction operation time, a total of 5 samples of the precipitates were dried at 110 ° C. for 24 hours, then calcined at 850 ° C. for 1 hour, and centrifuged. Average particle size measured by sedimentation type particle size distribution analyzer
60 to 0.92 μm, particle size range 0.10 to 1.00 μm
In the range of 80 to 84%, the particle size distribution width is 0.10 to 2.00 μm, and the specific surface area is 25 m ² /
and the purity of ZrO ₂ + Y ₂ O 3 is 99.
Yttria partially stabilized zirconium oxide fine powder containing 9 wt% or more of Y ₂ O ₃ / (ZrO ₂ + Y ₂ O ₃ ) of 8 mol% was obtained.

Example 5 Into a reaction tank having a volume of 5 liters up to an overflow outflow pipe, 2 waters adjusted to pH 12 with an aqueous NaOH solution were added.
1 liter was added and stirred. In this reaction tank under water stirring,
A mixed aqueous solution of 1.6 mol / liter of zirconium oxychloride containing 0.1% of total Zr amount as amorphous hydrated zirconium oxide and 0.14 mol / liter of calcium chloride at a flow rate of 42 ml / min and a concentration of 3.7 mol.
/ Liter NaOH aqueous solution at a flow rate of 42 ml / min at the same time with a constant flow pump to start the supply, and the reaction solution is flown out at a rate of 84 ml / min in terms of raw material solution continuously by an overflow method for neutralization and precipitation. The production reaction was carried out for 4.6 hours. The liquid in the reaction tank is
The pH was maintained at 12. The precipitate in the overflow effluent was separated and washed with water to remove impurities.
Immediately after the start of the reaction operation, immediately before the end of the reaction operation, and at equal intervals during the reaction operation time, a total of 5 samples of the precipitates were dried at 110 ° C. for 24 hours, then calcined at 900 ° C. for 1 hour, and centrifuged. Average particle size of 1.01 to 1.24 μm and particle size range of 0.10 to 2.00 measured by sedimentation type particle size distribution analyzer
88 to 91% in the range of μm, particle size distribution width of 0.10 to 3.00 μm, specific surface area of 15 m ²
/ G and the purity of ZrO ₂ + CaO are both 9
9.9 wt% or more, CaO / (ZrO ₂ + CaO) 8
A mol% calcia partially stabilized zirconium oxide fine powder was obtained.

Example 6 Into a reaction tank having a volume of 5 liters up to an overflow outflow pipe, 2 waters adjusted to pH 11 with an aqueous NaOH solution were added.
1 liter was added and stirred. In this reaction tank under water stirring,
A mixed aqueous solution of 2.4 mol / l of zirconium oxychloride containing 10% of the total Zr amount as non-hydrated zirconium oxide and 0.13 mol / l of magnesium chloride at a flow rate of 42 ml / min and a concentration of 5.3 m.
At the same time, supply of ol / l NaOH aqueous solution at a flow rate of 42 ml / min was started by a constant flow pump, and the reaction liquid was supplied from the overflow pipe at 84 ml / min as a raw material solution conversion value.
The neutralization precipitation formation reaction was continuously carried out for 2.6 hours by the overflow method of flowing out at a ratio of. The pH of the liquid in the reaction tank was maintained at 11. The precipitate in the overflow effluent was separated and washed with water to remove impurities. Immediately after the start of the reaction operation, immediately before the end of the reaction operation, and at three equally spaced points during the reaction operation time, a total of 5 samples of the precipitates were dried at 110 ° C. for 24 hours, and then calcined at 900 ° C. for 1 hour and centrifuged. Average particle size of 1.12 to 1.47 μm by sedimentation type particle size distribution measuring device, particle size range of 0.10 to 2.0
87-92% in the range of 0 μm, particle size distribution width of 0.10 to 3.00 μm, specific surface area of 17 m
² / g and ZrO ₂ + MgO purity are 99.
A magnesia partially stabilized zirconium oxide fine powder having a MgO / (ZrO ₂ + MgO) content of 9 mol% or more and 5 mol% was obtained.

Example 7 2 liters of water adjusted to pH 9 with aqueous ammonia was placed in a reaction vessel and stirred. 42 ml / min of a mixed aqueous solution of 1.54 mol / liter of zirconium oxychloride containing 1% of the total Zr amount as amorphous hydrated zirconium oxide and 0.10 mol / liter of yttrium chloride was placed in the reaction tank under water stirring. Flow rate and concentration 9.
At the same time, 1 wt% aqueous ammonia was supplied at a flow rate of 42 ml / min by a constant flow rate pump, and a neutralization precipitation forming reaction was carried out for 0.6 hours by a batch reaction system. The pH of the liquid in the reaction tank was maintained at 9. The formed precipitate was separated and washed with water to remove impurities. Immediately after the start of the reaction operation, immediately before the end of the reaction operation, and at equidistant intervals during the reaction operation time, three samples of the precipitates in each of the five reaction vessels were dried at 110 ° C. for 24 hours and then calcined at 900 ° C. for 1 hour. Then, the average particle size by the centrifugal sedimentation type particle size distribution measuring device 1.
09 to 1.28 μm, particle size range 0.10 to 2.00 μm
In the range of 79 to 81%, particle size distribution width of 0.10 to 3.00 μm, specific surface area of 16 m ² /
The purity of both g and ZrO ₂ + Y ₂ O ₃ is 99.9.
Yttria partially stabilized zirconium oxide fine powder having a Y ₂ O ₃ / (ZrO ₂ + Y ₂ O ₃ ) content of 3 mol% or more was obtained.

Comparative Example 1 Zirconium oxychloride, 1.54 mol /
2.5 liters of a mixed aqueous solution of liter and 0.10 mol / l of yttrium chloride, 2.5 liters of ammonia water having a concentration of 9.1 wt% was added to the mixture with stirring to obtain a precipitate concentration of ZrO ₂ + Y ₂ O ₃ A suspension having a pH of 9 was obtained at a conversion of 100 g / liter (containing 3.0 mol% as Y ₂ O ₃ ). The formed precipitate was separated and washed with water to remove impurities. After being dried at 110 ° C for 24 hours and then calcined at 850 ° C for 1 hour, those having an average particle diameter of 5.06 µm and a particle diameter range of 4.00 to 6.00 µm by a centrifugal sedimentation type particle size distribution analyzer 38% and particle size distribution width 1.00 to 25.0 μm, specific surface area 9 m ² /
The purity of g and ZrO ₂ + Y ₂ O ₃ is 98.6w.
t%, random 5 points sampled result of the composition analysis of the _{powder, Y 2 O 3 / (ZrO} 2 + Y 2 O 3) ranges stabilized zirconium oxide fine yttria portion of from 2.7 to 3.4 mole percent of A powder was obtained.

Comparative Example 2 1 liter of water adjusted to pH 12 with aqueous ammonia was placed in a reaction vessel and stirred. In the reaction tank under stirring, a mixed aqueous solution of 0.78 mol / liter of zirconium oxychloride and 0.07 mol / liter of calcium chloride was added at a flow rate of 42 ml / min and ammonia water having a concentration of 10.2 wt% was added at 42 ml / min. The supply was started at the same time by a constant flow rate pump, and a neutralization precipitation forming reaction was carried out by a batch reaction system for 0.8 hours. The pH of the liquid in the reaction tank is 1
2 and the precipitate concentration at the end of the reaction was ZrO ₂ + C
40 g / liter in terms of aO (8.0 mol% as CaO
Was included). The formed precipitate was separated and washed with water to remove impurities. This was dried at 110 ° C. for 24 hours and then calcined at 850 ° C. for 1 hour to obtain an average particle size of 4.65 μm by a centrifugal sedimentation type particle size distribution analyzer.
And having a particle size range of 4.00 to 6.00 μm 4
6%, a particle size distribution width of 1.00 to 21.0 μm, a specific surface area of 11 m ² / g, and a ZrO ₂ + CaO purity of
98.9 wt%, 5 points were randomly sampled from the powder and the composition was analyzed, and CaO / (ZrO ₂ + CaO)
A calcia partially stabilized zirconium oxide fine powder having a range of 7.7 to 8.3 mol% was obtained.

Comparative Example 3 2 liters of water adjusted to pH 11 with ammonia water was placed in a reaction vessel having a volume of 5 liters up to the overflow outflow pipe and stirred. 42 m of a mixed aqueous solution of 1.60 mol / l of zirconium oxychloride and 0.08 mol / l of magnesium chloride was placed in the reaction tank under stirring.
At a flow rate of 1 / min and at a flow rate of 42 ml / min, ammonia water having a concentration of 9.8 wt% was simultaneously started to be supplied by a constant flow rate pump, and a part of the reaction solution was converted into a raw material solution at a flow rate of 84 ml / min. The neutralization precipitation formation reaction was continuously carried out for 4.6 hours by the overflow method of flowing out at a ratio. The pH of the liquid in the reaction tank was maintained at 11, and the precipitate concentration at the end of the reaction was 9 converted to ZrO ₂ + MgO.
7.5 g / liter (containing 5.0 mol% as MgO)
Met. Separate the precipitate in the overflow effluent,
Impurities were removed by washing with water. This is 110 ℃
After being dried at 850 ° C. for 24 hours, it is calcined at 850 ° C. for 1 hour to obtain 65% of an average particle size of 4.08 μm and a particle size range of 3.00 to 5.00 μm measured by a centrifugal sedimentation type particle size distribution analyzer and a particle size. Distribution width 1.00 to 18.0
μm, specific surface area 12 m ² / g and (ZrO ₂ + Mg
O) has a purity of 99.0 wt% and the powder was randomly sampled at 5 points and the composition was analyzed. As a result, MgO / ZrO ₂ + M
Yttria partially stabilized zirconium oxide fine powder having a gO range of 4.8 to 5.3 mol% was obtained.

Claims (1)

[Claims] 1. A zirconium salt aqueous solution containing hydrated zirconium oxide, a stabilizer precursor aqueous solution, and an alkaline aqueous solution are supplied to a reaction tank while maintaining the pH of the liquid in the reaction tank at a substantially constant value. A method for producing a zirconium oxide powder, which comprises bringing these into contact with each other, separating the obtained precipitate, drying and firing.