JP2003206137A - Partially stabilized or stabilized zirconia fine powder, precursor thereof and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide stabilized zirconia fine powder which has a reduced alkali metal content and a sulfuric acid radical content, and to provide a method for producing the same by which the amount of ammonia components included in industrial waste water to be exhausted can remarkably be reduced. <P>SOLUTION: The zirconia fine powder has a composition containing stabilizing elements selected from Y, Ca, Mg, Al and rare earth elements, and in which the content of the alkali metal is ≤100 ppm, and the content of sulfuric acid radicals is ≤250 ppm. The zirconia fine powder has a crystallite diameter of ≤50 nm, a bulk density of ≥0.80 g/cm<SP>3</SP>, a tap density of ≥1.30 g/cm<SP>3</SP>and a tetragonal ratio of ≥90%. The stabilized zirconia fine powder is obtained by increasing the temperature of an aqueous solution containing the stabilizing elements, sulfuric acid radicals and zirconium to ≥50°C to precipitate zirconium basic sulfate, and adding the hydroxide of the alkali metal to the slurry to control the pH therein to ≥8, and performing filtering to obtain a zirconium hydroxide aggregate with the stabilizing elements fixed, and roasting the aggregate. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to fine powder of zirconia, particularly fine powder of partially stabilized or stabilized zirconia and a method for producing the same.

[0002]

2. Description of the Related Art Zirconia powder has excellent heat resistance and corrosion resistance, and has a high melting point and the like, and is a material that has been regarded as important in the field of fine ceramics in recent years. Zirconia powder shows a monoclinic system at room temperature and becomes a tetragonal system by firing, but this phase transition is reversible, and when the powder particle size is large or zirconium oxide alone is used, The reverse transition occurs in the process of cooling the tetragonal zirconia powder to room temperature, and usually causes a volume expansion of 4 to 5%. The reverse transition in the sintered body is not preferable in terms of volume change as well as strength and toughness.
Therefore, conventionally, a partially stabilized zirconia powder containing a small amount of a yttrium compound, a calcium compound, a magnesium compound, an aluminum compound, a rare earth element compound or the like as a stabilizer or a stabilized zirconia containing a relatively large amount of this stabilizer. A powder (a partially stabilized zirconia powder and a stabilized zirconia powder are sometimes collectively referred to as a stabilized zirconia powder) is put to practical use. By adding an appropriate amount of the stabilizer in this way, the transition energy from the tetragonal system to the monoclinic system is stored inside, and it becomes possible to obtain a sintered body having high strength and high toughness. Here, in the case of producing a sintered body having no phase transition, it is necessary that the zirconia powder is sufficiently fine and that the stabilizer is uniformly dispersed as conditions. Further, a molded density as sintered body of at least 2.50 g / cm ³ or more, it is required sintering density is 6.05 g / cm ³ or more.

As a method for producing such a stabilized zirconia powder, conventionally, a solution in which a stabilizing element such as yttrium is dissolved in a zirconium aqueous solution is used as a starting material, and (1) ammonia water or the like is added to coprecipitate. Method (2) method of hydrolyzing and replacing the precipitate in an organic solvent (3) method of hydrolyzing under high temperature and high pressure (4) method of synthesizing alkoxide compound and hydrolyzing it .

However, in the case of the above method (1), the hydroxide obtained is hard and requires a considerable pulverization treatment to make it into fine powder, and in the case of the method (2), the hydrolysis rate. Is slow, requires several tens to hundreds of hours of treatment, requires organic solvent recovery equipment and explosion-proof equipment, and increases energy costs. In the case of method (3), an autoclave is required, There are various serious problems such as high equipment cost and energy cost, and in the case of the method (4), a chemical process is required because a step of synthesizing an organometallic compound is required.

With respect to such problems, firstly, by improving the method (1), an economical zirconia fine powder, particularly a partially stabilized or finely sinterable fine powder which can be easily sinterable without crushing is provided. A method for producing stabilized zirconia fine powder has been developed and disclosed in Japanese Patent Publication No. 2-38527. That is, the method is to dissolve a water-soluble compound of at least one stabilizing element selected from yttrium compounds, calcium compounds, magnesium compounds, aluminum compounds, or rare earth element compounds, and a water-soluble zirconium compound in water, and to add sulfuric acid. After containing roots, the temperature of this aqueous solution is raised to precipitate a zirconium basic sulfate salt from the aqueous solution, and then an alkaline substance is added to the obtained slurry to adjust the pH to 8 or more, and further, A solid substance is collected by subjecting the slurry to a solid-liquid separation treatment, and the solid substance is treated with or without alkali washing to obtain a fine powder in which the hydroxide of the stabilizing element is fixed to the hydroxide particles of zirconium. It is a method for producing fine zirconium powder, which comprises roasting this so as to obtain it.

[0006]

In the above method, ammonia water or ammonia gas has been exclusively used as the alkaline substance for coprecipitating the stabilizing element in the precipitation of the zirconium basic sulfate. As the alkaline substance, if, for example, sodium hydroxide or the like is used, the problem that the sodium content remains as an impurity in the zirconia fine powder finally obtained, and the stabilization because it is a strong alkali This is because there is a problem such that calcium and aluminum added as agents are eluted again. The above-mentioned conventional method does not require special equipment, is an economical method that can easily obtain a fine zirconia powder having a small average particle size and a stabilizer uniformly dispersed therein, and is extremely significant. However, due to the recent environmental problems in which the regulation of the nitrogen content contained in industrial wastewater has become more stringent, it is becoming extremely difficult to use a large amount of ammonia water or ammonia gas as an alkaline substance. Reduction is required.

In view of the above situation, the present invention can obtain easily sinterable fine powder without performing the strong pulverization treatment as in the conventional neutralization method, and the nitrogen load on the environment can be significantly increased. It is an object of the present invention to provide an environment-friendly and economical method for producing stabilized zirconia fine powder that can be reduced.

[0008]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the inventors of the present invention have as a result of earnest studies, and finally obtained a hydroxide of a strongly alkaline alkali metal as a neutralizing agent. The inventors have found a method of reducing the content of alkali metal remaining as an impurity in the zirconia fine powder to be 100 ppm or less, and further reducing the amount of ammonia content contained in industrial wastewater to about 1/14 of the conventional amount.

That is, the present invention is, firstly, yttrium (Y), calcium (Ca), magnesium (M
g), aluminum (Al) and at least one stabilizing element selected from the group consisting of rare earth elements (R), having a crystallite diameter of 50 nm or less and a bulk density of 0.80 g /
cm ³ or more, tap density 1.30 g / cm ³ or more, tetragonal crystal ratio 90% or more, alkali metal content 100 pp
Secondly, at least one selected from the group consisting of yttrium, calcium, magnesium, aluminum and rare earth elements, partially stabilized or stabilized zirconia fine powder characterized by having a sulfate radical content of 250 ppm or less. Is a fine powder of zirconium hydroxide containing the stabilizing element of, having a bulk density of 0.40 g / c
m ³ or more, tap density is 0.60 g / cm ³ or more, alkali metal content is 100 ppm or less, and sulfate group content is 250 pp when zirconium oxide is used.
Thirdly, a precursor of a partially stabilized or stabilized fine zirconia powder characterized by having m or less is yttrium,
At least one stabilizing element selected from the group consisting of calcium, magnesium, aluminum and rare earth elements, sulfate and zirconium (Zr) are dissolved in the raw material aqueous solution by raising the temperature to 50 ° C. or higher to partially stabilize the element. The first step of obtaining a slurry in which a precipitate of zirconium basic sulfate having been adsorbed is deposited, and a hydroxide of an alkali metal is added to the slurry to adjust the pH to 8 or more to elute the sulfate group in the precipitate and A second step of coprecipitating the stabilizing element dissolved in the slurry as a hydroxide into the precipitate, and the slurry obtained in the second step is subjected to solid-liquid separation to contain the stabilizing element hydroxide. Partially stabilizing according to the first aspect, which comprises a third step of obtaining a fine powder of zirconium hydroxide, and then a fourth step of roasting the fine powder. The manufacturing method of Joka zirconia fine powder, the fourth, heating temperature of the raw material aqueous solution is 70 to 100
C., the alkali metal hydroxide is sodium hydroxide, and the pH value is 9 to 11, a fifth method for producing partially stabilized or stabilized zirconia fine powder, At least one stabilizing element selected from the group consisting of yttrium, calcium, magnesium, aluminum and rare earth elements, a raw material aqueous solution in which sulfate radicals and zirconium are dissolved are heated to 50 ° C. or higher to cause a part of the stabilizing elements. The first step of obtaining a slurry in which a precipitate of the adsorbed zirconium basic sulfate is deposited, in which the alkali metal hydroxide is added to the slurry to adjust the pH.
To 8 or more to elute the sulfate radicals in the precipitate and to coprecipitate the stabilizing element dissolved in the slurry as hydroxide in the precipitate, the slurry obtained in the second step Of the partially stabilized or stabilized zirconia fine powder according to the second aspect, which comprises a third step of solid-liquid separation to obtain a fine powder of zirconium hydroxide containing the hydroxide of the stabilizing element. A sixth method for producing a precursor is described.
The partial stabilization or stabilization according to the fifth aspect, wherein the temperature rise temperature of the raw material aqueous solution is 70 to 100 ° C., the alkali metal hydroxide is sodium hydroxide, and the pH value is 9 to 11. Provided is a method for producing a precursor of fine powdered zirconia powder.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for obtaining the stabilized zirconia powder of the present invention, first, a zirconium solution in which a water-soluble zirconium compound is dissolved, and a water-soluble compound of a stabilizing element for stabilizing the crystal of the product zirconia are used. A stabilizing element solution in which is dissolved and a sulfate group adjusting agent for sulfate group addition are mixed at a predetermined ratio to prepare a raw material aqueous solution (solution preparing step). The raw material aqueous solution is heated to a temperature of 50 ° C. or higher and held at a temperature of 50 ° C. or higher to complete the precipitation-forming reaction of the zirconium basic sulfate (temperature rising holding step: the first step up to here).

Next, a pH adjusting agent in which an alkali metal hydroxide is dissolved is added to this slurry containing the precipitate,
The neutralization reaction is completed by maintaining the pH at 8 or higher. That is, the sulfate group is eluted from the zirconium basic sulfate salt in the slurry to be removed and replaced with hydroxide ion, and the stabilizing element dissolved in the slurry is coprecipitated in the precipitate as hydroxide (neutralization step: 2 steps). The obtained slurry containing a precipitate of hydroxide is filtered and washed to obtain a solid substance, that is, a filter cake (filter washing step: third step).

The resulting filter cake is dried by heating to obtain zirconium hydroxide as a zirconia precursor (drying step). By baking the dried zirconium hydroxide, a stabilized zirconia or partially stabilized zirconia fine powder can be obtained as a product (roasting step: fourth step).

As the water-soluble zirconium compound for preparing the zirconium solution, zirconium oxychloride,
Zirconium oxynitrate or the like can be used. However, when zirconium oxynitrate is used, the effect of reducing the nitrogen load in industrial wastewater becomes small. As the water-soluble compound of the stabilizing element, an yttrium compound, a calcium compound, a magnesium compound, an aluminum compound, a rare earth element compound or the like is used. As the sulfate group adjusting agent, sodium sulfate, magnesium sulfate,
Aluminum sulfate or the like is used. As the alkali metal hydroxide as the pH adjuster, sodium hydroxide, potassium hydroxide or the like can be used.

The zirconium concentration in the raw material aqueous solution is ZrO 2.
_{2 as a} concentration of 50 to 300 g / L, preferably 80 to 1
It is 50 g / L. This liquid adjustment is performed at 30 ° C. or lower. The zirconium basic sulfate (ZrO ₂ ) _n (SO ₄ ) _m · xH ₂ O is produced by setting the sulfate concentration in the raw material aqueous solution to 0.3 to 0.8 mol with respect to 1 mol of zirconium. A preferred sulfate group concentration ratio is 0.4 to 0.6. The sulfate group concentration was 0.
When it is less than 3 mol, zirconium oxychloride is produced, and when it is more than 0.8 mol, zirconium oxysulfate or zirconium sulfate is produced and no precipitation of zirconium basic sulfate is produced.

The liquid temperature in maintaining the temperature of the raw material aqueous solution is 5
By setting the temperature to 0 ° C. or higher, preferably 70 to 100 ° C. (boiling point), and more preferably 70 to 90 ° C., the zirconium basic sulfate salt can be precipitated. In addition,
It is possible to change the aggregate particle size by changing the heating pattern. The holding time is 10 to 60 minutes.
In the neutralization by the addition of the pH adjusting agent using the alkali metal hydroxide, the pH is 8 or more, and preferably 9 to 11
Is. When the pH is 8 or more, preferably 9 or more, the residual amount of sulfate group in the precipitate obtained by the neutralization decreases, but when the pH exceeds 11, the residual amount of alkali metal in the precipitate increases. This means that the zirconium basic sulfate has the property of adsorbing ions. The neutralization retention time is 10 to 60 minutes.

The precipitate obtained in the neutralization step can be washed with pure water only, but the residual amount of alkali metal due to the hydroxide of the used alkali metal and the content of sulfate can be adjusted to the target level. A large amount of pure water is required for cleaning and reduction. However, by performing cleaning with diluted ammonia water before cleaning with pure water, the amount of pure water required for cleaning can be reduced to about 1/10. This is because the washing with a washing liquid containing an electrolyte has a higher washing efficiency than the washing with pure water in washing the basic salt. In this cleaning step, dilute ammonia water is used, but since the concentration and quantity are small, the nitrogen load per 1 kg of ZrO ₂ can be about 1/14 of that of the conventional technique.

The fine powder obtained here serves as a stabilizer.
Zirconium hydroxide ZrO (OH)
Hydroxide Y (OH)₃ , Calcium hydroxide Ca
(OH)₂ , Magnesium hydroxide Mg (OH)₂ ,
Aluminum hydroxide Al (OH)₃ , Of rare earth elements
Hydroxide is fixed. This hydroxide is
Although it is a precursor of luconia,
Alkali metal water without monia water or ammonia gas
By using an oxide such as sodium hydroxide
In the neutralization step, the pH is set within the specified range,
Easily elute sulfate radicals while suppressing the amount of alkali metal adsorption
So, when using zirconium oxide, alkali metal content
The amount (according to atomic absorption method; the same applies below) is 100 ppm or less.
Below, the sulfate content (by ICP. The same applies hereinafter) is 25.
It can be set to 0 ppm or less, and at the same time, it has a bulk density (bulk density).
Depends on the meter. same as below. ) Is 0.40 g / cm ^Threethat's all,
Tap density (By tapping 1000 times.
Same. ) Is 0.60 g / cm^ThreeZirconium water
This hydroxide allows you to obtain aggregated particles of oxide
After the drying step,
It is possible to increase the processing amount of
It is possible to improve productivity and reduce production costs.

The hydroxide as a precursor has a temperature of 900 ° C. or higher.
Above all, it is preferably roasted at 1000 to 1200 ° C. this
Zirconia powder obtained by roasting is also the hydroxide of
It has excellent characteristics according to the characteristics. This Jill
Konia powder has a large aggregate center diameter of 3 to 30 μm,
Easy to make fine powder of 1μm or less by simple crushing operation
be able to. In addition, this zirconia powder is
Metal content is 100ppm or less, sulfate content is 250
ppm or less, crystallite diameter (according to X-ray diffraction method.
the same. ) Is 50 nm or less, and the bulk density is 0.80 g / cm.
^ThreeAbove, tap density is 1.30g / cm^ThreeHigher than that,
The BET specific surface area (based on the BET one-point method.
Same. ) Is 10 m²/ G or less, tetragonal crystal ratio (X-ray diffraction
By law. ) Is 90% or more, and the stabilization rate is high. further,
Molding density is the target value of 2.50 g / cm ^ThreeWith the above, sintering dense
Degree is 6.05g / cm^ThreeClear each target value
Also, the bending strength of the sintered body is equal to or higher than that of conventional products.
Is.

[0019]

EXAMPLES Examples for the preparation of partially stabilized zirconia are described. Zirconium oxychloride (ZrOCl ₂ · 8H ₂ 0) was dissolved in pure water as a zirconium solution to obtain ZrO ₂
An aqueous solution having a concentration of 300 g / L was dissolved in yttrium oxide (Y ₂ O ₃ 99%) as a stabilizer solution with hydrochloric acid to a Y ₂ O ₃ concentration of 180 g / L.
Anhydrous sodium sulfate powder (Na ₂ S
O ₄ 99.5%) was prepared.

The zirconium aqueous solution was a ZrO ₂ concentration of 1333 ml of an aqueous solution corresponding to 100 g / L, and the stabilizer was Y ₂ O ₃ / PSZ (PSZ is a partially stabilized zirconia) at 2.75 mol%. 115m which is considerable
l of the aqueous solution and mixed with a sulfate group adjusting agent
0.6 mol in sulfate radical (SO ₄ ) per rO ₂ -mol
An amount of 279.5 g corresponding to 1 was added, and a further 255
4000 ml of raw material aqueous solution prepared by adding 1.5 g of pure water was prepared. The obtained raw material aqueous solution was colorless and transparent, and the liquid temperature was 25 ° C.

This raw material aqueous solution was heated to 80 ° C. for 60 minutes, and then kept heated for 60 minutes to obtain a slurry in which a precipitate of zirconia basic sulfate was deposited (first step). 48% sodium hydroxide was added to the slurry as a pH adjuster to adjust the pH to 10 (at this time, the alkali equivalent was 1.05, and the added amount was 616 g).
A slurry containing a precipitate of zirconium basic sulfate in which the stabilizing element was coprecipitated as a hydroxide was obtained by holding for 2 minutes (second step).

The resulting slurry was filtered through a filter press, and 0.2 mol% ammonia water in an amount corresponding to precipitate ZrO ₂ -kg per 10L ZrO ₂ -kg per 9
After washing with pure water in an amount corresponding to 0 L, the product was held in a tray dryer at 150 ° C. in the atmosphere and dried to obtain a hydroxide as a precursor (third step). This hydroxide has an aggregate particle size of 5.0 μm as measured by the Microtrac method (D50 diameter) (hereinafter the same), a bulk density of 0.59 g / cm ^{3 as} measured by a bulk densitometer, and a tap by tapping 1000 times. BET-1 with a density of 0.74 g / cm ^3.
The specific surface area was 213 m ² / g as measured by the dot method.

Next, the hydroxide was roasted in an electric furnace at 1000 ° C. in the atmosphere. The obtained roasted product was partially stabilized zirconia, and the physical properties thereof are shown in Table 1. Furthermore, when the nitrogen load state of the treatment liquid was investigated, it was 0 mol per ZrO ₂ -kg in the neutralization treatment step (second step), and 2.0 mol per ZrO ₂ -kg in the filter washing step (third step). , ZrO ₂ -The total amount per kg is 2.0
It was mol.

Comparative Example A comparative example of the production of partially stabilized zirconia will be described. The same zirconium solution and stabilizer solution as those prepared in the examples were respectively added to 667 ml of an aqueous solution having a ZrO ₂ concentration of 50 g / L and Y ₂ O ₃ / PS.
58 ml of a 2.75 mol% equivalent aqueous solution was mixed with Z, and ammonium sulfate powder was added as a sulfate radical modifier to this mixture in an amount of 0.6 mol equivalent of 128.6 g of SO ₄ per ZrO ₂ -mol, Pure water 3275.8
g to make 4000 ml of raw material aqueous solution. This raw material aqueous solution was a colorless transparent liquid at 25 ° C. This raw material aqueous solution was heated to 80 ° C. for 60 minutes and kept at the same liquid temperature for 120 minutes as it was, and then 503 g of 1.05 equivalent of 25% ammonia water was added as a pH adjuster (at this time, p
H is 9.2. ) A slurry was obtained by holding for 10 minutes. Then, this slurry was filtered by a filter press, and the solid content was washed with 10 L of ZrO ₂ -kg equivalent to 0.2 mol% ammonia water.
After washing with 90 L of pure water equivalent to rO ₂ -kg, drying was performed at a temperature of 150 ° C. in the atmosphere by a tray dryer. The obtained hydroxide as a precursor was measured by the same measuring method as in the example, and had an aggregate particle size of 3.0 μm, a bulk density of 0.33 g / cm ³ , and a tap density of 0.49 g / cm.
³ , and the specific surface area was 198 m ² / g.

The obtained hydroxide was roasted in an electric furnace at a temperature of 1000 ° C. in the atmosphere to obtain partially stabilized zirconia. The characteristic values of this partially stabilized zirconia are also shown in Table 1. The nitrogen load in the neutralization step with aqueous ammonia was 26.8 mol per ZrO ₂ -kg,
Said nitrogen load in the filtration washing process with ZrO ₂ -kg per 2.0 mol, total nitrogen load per ZrO ₂ -kg was 28.8Mol.

[0026]

[Table 1]

From the comparison between the above examples and comparative examples, the zirconium hydroxide as the precursor of the present invention has a large bulk density and tap density, a small specific surface area and a high compactness, and the agglomerated particle size. Is large, and it can be expected that productivity will increase thereafter.
The partially stabilized zirconia obtained by roasting has a large aggregate particle size, high bulk density and tap density, and a low specific surface area, as in the case of the precursor hydroxide. Although the crystallite diameter is slightly large, there is no big difference, and the tetragonal crystal ratio is steadily showing 90% or more at the same level. There are few sulfate radicals, and Na from the raw material is sufficiently reduced by optimizing the pH range. Further, in the neutralization step, the use of a hydroxide of an alkali metal has a high pH and makes it possible to reduce SO ₄ . Furthermore, the molding density is the target of 2.50 g / c
m ³ or more and the sintered density of 6.05 g / cm ³ or more, which is the target, are cleared. Further, it is possible to sufficiently reduce the problem of nitrogen load in the wet reaction step and the filter cleaning step.

[0028]

As is apparent from the above description, according to the present invention, it is possible to provide a stabilized zirconia or partially stabilized zirconium fine powder having high molding density and sintering density and excellent characteristics. According to the method of the invention, it is possible to easily obtain the stabilized zirconia fine powder having the above-mentioned excellent properties without forming the hardly crushable aggregates found in the conventional neutralization method. Since agglomerated particles of zirconium hydroxide with a large bulk density can be obtained, the amount of charge in the post-process can be increased to improve the production efficiency, reduce the cost of the product, and significantly reduce the nitrogen load on the environment. That is the effect.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Katsuaki Okabe             1-8-2 Marunouchi, Chiyoda-ku, Tokyo             Within Wa Mining Co., Ltd. F-term (reference) 4G031 AA01 AA03 AA04 AA07 AA08                       AA12 AA29 GA01                 4G048 AA02 AA03 AB02 AB06 AB08                       AC08 AD03 AD06 AE05

Claims (6)

[Claims] 1. A tap containing at least one stabilizing element selected from the group consisting of yttrium, calcium, magnesium, aluminum and rare earth elements, having a crystallite diameter of 50 nm or less, a bulk density of 0.80 g / cm ³ or more, and a tap. A partially stabilized or stabilized zirconia fine powder having a density of 1.30 g / cm ³ or more, a tetragonal crystal ratio of 90% or more, an alkali metal content of 100 ppm or less, and a sulfate group content of 250 ppm or less. 2. A fine powder of zirconium hydroxide containing at least one stabilizing element selected from the group consisting of yttrium, calcium, magnesium, aluminum and rare earth elements, having a bulk density of 0.40 g / c.
m ³ or more, tap density is 0.60 g / cm ³ or more, alkali metal content is 100 ppm or less, and sulfate group content is 250 pp when zirconium oxide is used.
Precursor of partially stabilized or stabilized zirconia fine powder characterized by being m or less. 3. Stabilization by heating a raw material aqueous solution in which at least one stabilizing element selected from the group consisting of yttrium, calcium, magnesium, aluminum and rare earth elements, sulfate and zirconium is heated to 50 ° C. or higher. A first step of obtaining a slurry in which a precipitate of zirconium basic sulfate in which a part of elements is adsorbed is deposited, and a hydroxide of an alkali metal is added to the slurry to adjust the pH.
To 8 or more to elute the sulfate group in the precipitate and to coprecipitate the stabilizing element dissolved in the slurry as hydroxide in the precipitate, and the slurry obtained in the second step. Third, solid-liquid separation to obtain fine powder of zirconium hydroxide containing hydroxide of the stabilizing element
The method for producing a partially stabilized or stabilized zirconia fine powder according to claim 1, comprising a step, and then a fourth step of roasting the fine powder. 4. The rising temperature of the raw material aqueous solution is 70 to 10.
The temperature is 0 ° C., the alkali metal hydroxide is sodium hydroxide, and the pH value is 9 to 11.
A method for producing the partially stabilized or stabilized fine zirconia powder as described. 5. Stabilization by heating a raw material aqueous solution in which at least one stabilizing element selected from the group consisting of yttrium, calcium, magnesium, aluminum and rare earth elements, sulfate and zirconium is heated to 50 ° C. or higher. A first step of obtaining a slurry in which a precipitate of zirconium basic sulfate in which a part of elements is adsorbed is deposited, and a hydroxide of an alkali metal is added to the slurry to adjust the pH.
To 8 or more to elute the sulfate group in the precipitate and to coprecipitate the stabilizing element dissolved in the slurry as hydroxide in the precipitate, and the slurry obtained in the second step. Third, solid-liquid separation to obtain fine powder of zirconium hydroxide containing hydroxide of the stabilizing element
The method for producing a precursor of partially stabilized or stabilized zirconia fine powder according to claim 2, characterized by comprising the steps of: 6. The elevated temperature of the raw material aqueous solution is 70 to 10.
The temperature is 0 ° C., the hydroxide of the alkali metal is sodium hydroxide, and the pH value is 9 to 11.
A method for producing a precursor of the partially stabilized or stabilized fine zirconia powder as described.