JP2003246623A - Method for producing zirconia powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple method of producing fine zirconia powder. <P>SOLUTION: In the method of producing zirconia powder, a zirconium salt is fired in a hydrogen chloride-containing atmosphere. In the same method, the zirconium salt consists of zirconium oxychloride. The method of producing zirconia powder includes a stage 1 where a zirconium salt is calcined to obtain a calcined material; and a stage 2 where the calcined material is fired in a hydrogen chloride-containing atmosphere. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing zirconia powder.

[0002]

2. Description of the Related Art A zirconia sintered body obtained by sintering zirconia powder has excellent strength, toughness, rigidity and abrasion resistance, and is therefore used in various ceramics for structural materials. Recently, the zirconia sintered body has been used particularly for ferrules, which are parts of optical fiber connectors, because of its outstanding strength, rigidity, and wear resistance. Among the zirconia sintered bodies, since the zirconia sintered body composed of fine sintered particles has the above-mentioned physical properties,
There is a particular need for fine zirconia powder having a primary particle size of 0.1 μm or less.

As a method for producing fine zirconia powder,
For example, Japanese Patent Laid-Open No. 5-24841 discloses a manufacturing method including the following steps. (1) A step of dissolving zirconium oxychloride in water to obtain a solution. (2) A step of heating and hydrolyzing the solution to precipitate hydrated zirconia. (3) A step of drying the hydrated zirconia. (4) A step of firing the dried hydrated zirconia at 850 ° C. to obtain a zirconia powder having a primary particle size of 0.1 μm.

[0004]

However, the above production method has a problem that it takes as long as 80 hours to reach the hydrolysis rate of 84% because the hydrolysis rate in the step (2) is slow. . An object of the present invention is to provide a simple method for producing fine zirconia powder.

[0005]

Means for Solving the Problems As a result of earnest studies for achieving the above object, the present inventor has found that by firing a zirconium salt in an atmosphere containing hydrogen chloride, fine particles of fine particles can be obtained without hydrolysis. The inventors have found that zirconia powder can be obtained, and completed the present invention. That is, the present invention provides a method for producing zirconia powder, which comprises a step of firing a zirconium salt in an atmosphere containing hydrogen chloride. The present invention also provides a method for producing zirconia powder, which comprises the following steps. Step 1: A step of calcining a zirconium salt to obtain a calcined product. Step 2: A step of firing the calcined product in an atmosphere containing hydrogen chloride.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the zirconium salt used in the present invention include zirconium oxychloride, zirconium nitrate, zirconium chloride and zirconium sulfate. Of these, zirconium oxychloride is preferable. As the zirconium salt, it is possible to use hydrated zirconia obtained by dissolving zirconium oxychloride in water and hydrolyzing it under heating, but since the hydrolysis step takes time, it is not possible to use such hydrated zirconia. Not preferable. When it is necessary to produce a high-purity zirconia powder, a high-purity zirconium salt may be used.

By mixing the zirconium salt used in the present invention with a seed crystal having a primary particle size of about 0.1 μm or less, a zirconia powder having a small particle size can be obtained. The seed crystal is considered to act as a starting point in the formation of particles of zirconia powder having a small particle size. To obtain a zirconia powder having an average primary particle size of 0.1 μm or less,
A seed crystal having a primary particle size of about 0.1 μm or less may be used.

Examples of seed crystals include zirconia powder and zirconia gel. The amount of seed crystals used is usually 0.1 to 20% by weight, with the total weight of the amount of zirconium salt converted to zirconia and the amount of seed crystals being 100% by weight.
Is. As the amount of seed crystals used in this range increases, a zirconia powder having a smaller particle size tends to be obtained.

As a method of mixing the zirconium salt and the seed crystal, a ball mill, a dyno mill, a vibration mill, a vertical granulator and a Henschel mixer,
A method of mixing by a mixing device that is commonly used in industry can be exemplified. The mixing may be either a dry mixing method or a wet mixing method. The seed crystals are
It can also be mixed with the zirconium salt after calcination described later. The particle size of the zirconium salt after calcination can be controlled by the calcination temperature. The lower the calcination temperature, the smaller the particle size tends to be.

The zirconium salt may be used in combination with a stabilizer or its precursor in order to improve the strength of the zirconia sintered body obtained by sintering the zirconia powder obtained by the production method of the present invention. As a stabilizer
Examples thereof include oxides of one or more elements selected from the group consisting of Y, Ce, Ca, Ti, and Mg, and compounds of the elements that are oxides of the elements upon firing. The amount of the stabilizer used is the sum of the amount of the stabilizer and the amount of zirconium salt converted to zirconia to be 1
As 00 mol%, it is usually 0.1 to 20 mol%.
When a zirconium salt is used in combination with a seed crystal, the above-mentioned “amount of zirconium salt converted to zirconia” means the sum of the amount of zirconium salt converted to zirconia and the amount of seed crystal converted to zirconia. .

In order to improve the density of the zirconia sintered body obtained by sintering the zirconia powder obtained by the production method of the present invention, the zirconia powder can be used in combination with a sintering aid or its precursor. . Alumina, such as transition alumina and α-alumina, as sintering aids,
And, such as aluminum hydroxide, aluminum nitrate, aluminum sulfate and aluminum oxalate,
An aluminum compound which becomes alumina by firing can be exemplified. When aluminum hydroxide, transition alumina or α-alumina is used, a powdery sintering aid having excellent dispersibility is preferable. The amount of the sintering aid used is usually 0.1 to 10% by weight, where the total amount of the amount of the sintering aid and the amount of zirconium salt converted to zirconia is 100% by weight. Where the zirconium salt is used in combination with a stabilizer, said 100% by weight also comprises the amount of stabilizer,
When a zirconium salt is used in combination with a seed crystal, the above-mentioned “amount of zirconium salt converted to zirconia” is
It means the sum of the amount of zirconium salt alone converted to zirconia and the amount of seed crystals converted to zirconia.

Prior to the firing step in the present invention, the zirconium salt can be dried in order to remove water present on the surface of the zirconium salt. Drying is usually performed in air, and the drying temperature is usually 50 ° C or higher and lower than 200 ° C.

Before the firing step in the present invention, the zirconium salt can be calcined in order to remove the water of crystallization in the zirconium salt. In this case, the method for producing zirconia powder includes the following steps. Step 1: A step of calcining a zirconium salt to obtain a calcined product. Step 2: A step of firing the calcined product in an atmosphere containing hydrogen chloride.

The calcination is usually carried out in air, and the preferable calcination temperature depends on the type of zirconium salt, but it is usually 2
The temperature is not lower than 00 ° C and lower than 700 ° C. For unknown reasons,
When the calcination temperature rises, the average primary particle size of the zirconia powder produced tends to increase. A crushing step of the zirconium salt may be provided before the firing step in the present invention.
The pulverization process may reduce the average primary particle size of the zirconia powder produced or narrow the particle size distribution. Grinding can be carried out by a grinder commonly used in industry such as a ball mill, a vibration mill, a dynamic mill and a fine mill.

The firing step in the present invention is performed in an atmosphere containing hydrogen chloride. Hydrogen chloride gas may be used in combination with inert gases such as nitrogen and argon, air and gases such as oxygen. The concentration of hydrogen chloride in the atmosphere containing hydrogen chloride is preferably 1% by volume or more, from the viewpoint of obtaining a zirconia powder having a uniform shape, and from the viewpoint of obtaining a zirconia powder giving a zirconia sintered body having a high density. It is more preferably 5 to 95% by volume. The concentration may be 100% by volume.

When zirconium oxychloride is used as the raw material, it is possible to control the hydrogen chloride concentration to the above value by holding the hydrogen chloride gas generated from its decomposition in the firing furnace.

The preferable temperature of the firing step in the present invention is 700 ° C. to 1100 ° C. from the viewpoint of obtaining a zirconia powder giving a zirconia sintered body having a high density. A preferable holding time in the temperature range in the firing step is 0.5 to
10 hours. Although details are unclear, it is considered that the stabilizer and the sintering aid are more uniformly dispersed in the zirconia particles in this firing step because the firing step is a reaction via a gas phase.

The zirconia powder obtained by the production method of the present invention is pulverized by a pulverizer which is commonly used in industry, such as a wet ball mill, a dry ball mill, a vibration mill, a dyno mill, a dynamic mill and a fine mill. As a result, it is possible to obtain a zirconia powder having finer particles and excellent dispersibility, which can produce a zirconia sintered body having a higher density. When pulverizing the zirconia powder in combination with a stabilizer or a sintering aid, the pulverized zirconia powder has excellent dispersibility, so that the zirconia powder may be mixed well with the stabilizer or the sintering aid. it can.

According to the production method of the present invention, a zirconia powder having a uniform particle shape can be produced directly from a zirconium salt, and the zirconia powder is shaped and sintered to obtain a highly dense sintered product. The body can be manufactured.

As a method for producing a zirconia sintered body from the zirconia powder obtained by the production method of the present invention,
Examples of methods A and B that are usually used industrially and include the following steps can be illustrated.

Method A (1) A step of dispersing a zirconia powder in water to obtain a dispersion liquid. (2) A step of adding a resin binder such as polyvinyl alcohol or an acrylic resin emulsion to the dispersion liquid to obtain a slurry. (3) A step of drying the slurry with a spray dryer to obtain granules. (4) A step of molding the granules by a molding method such as a uniaxial pressing method or a hydrostatic pressing method to obtain a molded body. (5) Molded product in air atmosphere at 1250 ° C to 1600 ° C
A step of obtaining a high-density zirconia sintered body by sintering in the temperature range of.

Method B (1) A step of kneading a mixture of zirconia powder and an organic compound such as a thermoplastic resin to obtain a kneaded product. (2) A step of molding the kneaded product by a molding method such as an injection molding method or an extrusion molding method to obtain a molded body. (3) A step of heating the molded body to burn the organic compound in the molded body to obtain a heat-treated product. (4) A step of sintering the heat-treated product to obtain a high-density zirconia sintered body.

When the zirconia powder obtained by the production method of the present invention is used in the above method B, step (1)
Since it is possible to increase the content of zirconia powder in the kneaded product obtained in step (3), it is possible to suppress the shrinkage rate of the molded body in step (3) and the shrinkage rate of the heat-treated product in step (4) to a low level, As a result, a zirconia sintered body with high dimensional accuracy and high density can be manufactured.

The particles in the zirconia powder obtained by the production method of the present invention have high crystallinity even though they are fine particles, and have a uniform primary particle size. Therefore, the zirconia powder is polished. It is excellent as a raw material for the production of abrasives, which is unlikely to cause polishing scratches on the surface of articles.

The zirconia powder obtained by the manufacturing method of the present invention is used as an abrasive for magnetic media for removing stains on a magnetic head, and as an abrasive added to a toner for removing stains on a drum of a copying machine. It is suitable. Since the magnetic substance used in the magnetic medium and the carbon powder used as the toner are fine particles, and the zirconia powder obtained by the production method of the present invention is also fine particles, both can be uniformly mixed.

Since the zirconia powder obtained by the production method of the present invention can be easily dispersed in a resin or a solvent (a solvent when a resin dispersed in a solvent is used), abrasion resistance of the resin It is suitable as a filler for improving performance such as rigidity and strength.

The zirconia powder obtained by the production method of the present invention is suitable for injection molding and slip casting. The sintered body obtained from the zirconia powder has high density, high strength, high rigidity and high wear resistance, and is therefore suitable for use as a sintered body, especially for ferrules and ground media.

Further, the zirconia powder obtained by the production method of the present invention is suitable for abrasives, resin fillers and magnetic media fillers.

[0029]

EXAMPLES The present invention will now be described with reference to examples, but the present invention is not limited thereto. 1. Observation of particle shape The shape of the primary particles was determined by observing the powdery sample with a scanning electron microscope of the model T-300 manufactured by JEOL Ltd. 2. Measurement of BET Specific Surface Area The BET specific surface area was measured by a BET specific surface area measuring device manufactured by Shimadzu Corporation under the trade name of Flowsorb 2300II.

Example 1 Zirconium oxychloride (special grade reagent) 10 manufactured by Wako Pure Chemical Industries, Ltd.
0 g was dried in air at 130 ° C. for 5 hours. To this, as a seed crystal, zirconia powder (trade name: TZ0Y) having a primary particle size of 0.1 μm manufactured by Tosoh was added, and mixed by a ball mill for 6 hours to obtain a mixture. The amount of seed crystals added was 10% by weight, with the total amount of the amount of zirconium oxychloride converted to zirconia and the amount of seed crystals being 100% by weight. 90% by volume of hydrogen chloride and 10% by volume of air
And hold at 830 ° C for 1 hour in an atmosphere consisting of
Zirconia powder was obtained. The primary particle diameter of the zirconia powder is 0.1 μm, and the BET specific surface area is 15.4 m ² / g.
And the particles had a uniform polyhedral shape.

Yttrium oxide having a primary particle size of 0.4 μm made by Japan Yttrium was added to the zirconia powder, and the total amount of the zirconia powder and the yttrium oxide was 100 mol%.
As an amount of 3 mol% (amount of Y ₂ O ₃ × 100 / (amount of ZrO ₂ + amount of Y ₂ O ₃ ) = 3), pulverized with a wet ball mill for 12 hours and dried to obtain a dry powder. Obtained. The dry powder was molded into pellets by a uniaxial press, and the obtained molded body was sintered at 1350 ° C. to have a density of 6.00 g / cm 3.
³ to obtain a sintered body of, also, the obtained compact was sintered at 1400 ° C. to obtain a sintered body density of 6.02 g / cm ³ in.

Example 2 Zirconium oxychloride (special grade reagent) 10 manufactured by Wako Pure Chemical Industries, Ltd.
0 g was dried in air at 130 ° C. for 5 hours. To this, as a seed crystal, zirconia powder with a primary particle size of 0.1 μm (trade name: TZ0Y) manufactured by Tosoh and yttrium oxide with a primary particle size of 0.4 μm manufactured by Japan Yttrium were added and mixed by a ball mill for 6 hours. did. The amount of seed crystals added was 3% by weight, with the total amount of zirconium oxychloride converted to zirconia and the amount of seed crystals being 100% by weight,
The amount of yttrium oxide added was 3 mol% based on the total amount of zirconium oxychloride converted to zirconia, the amount of seed crystals, and the amount of yttrium oxide as 100% by weight. The mixture was baked by holding it at 950 ° C. for 1 hour in an atmosphere consisting of 90% by volume of hydrogen chloride and 10% by volume of air to obtain a powder. The powder was pulverized with a wet ball mill for 12 hours to obtain zirconia powder. The primary particle diameter of the zirconia powder is 0.1 μm, and the BET specific surface area is 18.0 m.
² / g, and the particles had a uniform polyhedral shape.

The zirconia powder was shaped into pellets by a uniaxial press, the obtained shaped body was sintered at 1350 ° C. to obtain a sintered body having a density of 6.02 g / cm ³ , and the obtained shaped body was obtained. Sintered at 1400 ° C to give a density of 6.04 g / c
A sintered body of m ³ was obtained.

Example 3 Zirconium oxychloride (special grade reagent) 10 manufactured by Wako Pure Chemical Industries, Ltd.
0 g was dried in air at 130 ° C. for 5 hours. 1 in an atmosphere consisting of 30% by volume hydrogen chloride and 70% by volume air
The powder was obtained by holding at 000 ° C. for 1 hour and firing. Total firing time (temperature increase from room temperature to 1000 ° C + 1000
The firing time (1 hour) at 1000C + the cooling time from 1000 ° C to room temperature) was about 6 hours. The primary particle size of the powder was 0.2 μm, the BET specific surface area was 7.8 m ² / g, and the particles had a uniform polyhedral shape.

Example 4 Zirconium oxychloride (special grade reagent) 10 manufactured by Wako Pure Chemical Industries, Ltd.
0 g was dried in air at 130 ° C. for 5 hours. In addition, the total amount of yttrium oxide having a primary particle size of 0.4 μm made in Japan and converted to zirconium oxychloride and the total amount of yttrium oxide was 100 mol%.
Was added in an amount of 3 mol% and mixed by a ball mill for 6 hours to obtain a mixture. The mixture was held in an atmosphere consisting of 90% by volume of hydrogen chloride and 10% by volume of air at 950 ° C. for 1 hour for firing to obtain a zirconia powder. The primary particle size of the zirconia powder is 0.1 μm,
The BET specific surface area was 15.0 m ² / g.

Example 5 Zirconium oxychloride (special grade reagent) 10 manufactured by Wako Pure Chemical Industries, Ltd.
0 g was dried in air at 130 ° C. for 5 hours. As a seed crystal, a zirconia gel manufactured by Nissan Chemical Co., Ltd. was added to this so that the total amount of zirconium oxychloride converted to zirconia and the amount of the seed crystal was 100% by weight, and the amount was 5% by weight. Then, the mixture was mixed by a ball mill for 6 hours to obtain a mixture. 90% by volume of hydrogen chloride and 10% by volume of air
In an atmosphere consisting of, was held at 800 ° C. for 1 hour and fired to obtain a zirconia powder. The primary particle diameter of the zirconia powder was 0.1 μm, and the BET specific surface area was 16.0 m ² / g.
Met.

Example 6 Zirconium oxychloride (special grade reagent) manufactured by Wako Pure Chemical Industries, Ltd. as a raw material was calcined in air at 600 ° C. for 3 hours to obtain a calcined product. The calcined product had an average particle size of 0.4
μm of Y ₂ O _{3 (} 5.25% by weight) was added (total amount of Y ₂ O ₃ and calcined product was 100% by weight), and the mixture was mixed by a ball mill for 6 hours to obtain a mixture. An atmosphere containing the mixture of 30% by volume of hydrogen chloride and 70% by volume of air in an atmosphere of 900
It was kept at ℃ for 1 hour and baked to obtain zirconia powder particles. The primary particle size of the zirconia powder was 10 to 50 nm, the BET specific surface area was 23.4 m ² / g, and the particles had a uniform polyhedral shape.

Example 7 Zirconia powder particles were obtained in the same manner as in Example 6 except that the calcination temperature of zirconium oxychloride was 650 ° C. The primary particle size of the zirconia powder was 30 to 80 nm, the BET specific surface area was 19.4 m ² / g, and the particles had a uniform polyhedral shape. In the present invention, since commercially available zirconium oxychloride can be used directly as a raw material, no step was required before the calcination step. The time required for producing each of the zirconia powder particles in Examples 6 and 7 was about 8 for the calcination step.
Time, 6 hours in total for the adding step and the mixing step, and about 6 hours for the firing step (heating time from room temperature to 900 ° C., and
(Including the time for cooling from 900 ° C. to room temperature).

Example 8 A zirconia powder was obtained in the same manner as in Example 6 except that a calcined product of zirconium oxychloride was fired at 1000 ° C. in an atmosphere composed of 5% by volume of hydrogen chloride and 95% by volume of air. . The primary particle size of the zirconia powder was 40 to 90 nm, the BET surface area was 17.3 m ² / g, and the particles had a uniform polyhedral shape.

Example 9 0.25% by weight of Y ₂ O _{3 having} an average particle size of 0.4 μm and AKP-30 (trade name of alumina, manufactured by Sumitomo Chemical Co., Ltd.) manufactured by Nippon Yttrium Co., Ltd. were used as a calcined product. 0.25% by weight (the total amount of Y ₂ O ₃ , alumina and the calcined product is 100% by weight) and mixed with the mixture at 1000 in an atmosphere consisting of 30% by volume of hydrogen chloride and 70% by volume of air. Zirconia powder was obtained in the same manner as in Example 6 except that the calcination was performed.

The resulting zirconia powder was pulverized with a wet ball mill for 12 hours and then dried to obtain a dry powder. Pellets were molded by the same method as in Example 1 and sintered at 1350 ° C. to obtain a sintered body having a density of 6.05 g / cm ³ .

Example 10 2 kg of zirconium oxychloride was placed in a quartz container having a volume of 50 liters and fired by a method of removing generated gas into the atmosphere. Hydrogen chloride gas generated during calcination is 20
Since it is 0 liters or more, the concentration of hydrogen chloride contained in the atmosphere is considered to be 10% or more. The zirconia powder has a primary particle size of 30 to 60 nm and a BET surface area of 2
It was 4.1 m ² / g, and the particles had a uniform polyhedral shape.

Comparative Example 1 A powder was obtained in the same manner as in Example 3 except that the powder was fired in an air atmosphere. The powder was strongly agglomerated and could not be ground with a wet ball mill and contained a solid mass with a particle size of about 0.1 mm. The particles had a non-uniform shape when observed with a scanning electron microscope.

[0044]

The zirconia powder produced by the production method of the present invention is suitable for injection molding and slip casting, and the obtained sintered body has high density, high strength, high rigidity and high wear resistance. Suitable for sinter applications, especially ferrules and crushed media. Furthermore, the zirconia powder produced by the production method of the present invention is suitable for abrasives, resin fillers, and magnetic media fillers. According to the production method of the present invention, fine zirconia powder suitable for such a wide range of applications can be easily produced in a short time, so the present invention is industrially very useful.

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Claims (15)

[Claims] 1. A method for producing zirconia powder, which comprises firing a zirconium salt in an atmosphere containing hydrogen chloride. 2. The method for producing a zirconia powder according to claim 1, wherein the zirconium salt is zirconium oxychloride. 3. The method for producing a zirconia powder according to claim 1, wherein the concentration of hydrogen chloride in the atmosphere containing hydrogen chloride is 1% by volume or more. 4. The method for producing a zirconia powder according to claim 1, wherein the firing temperature is in the range of 700 to 1100 ° C. 5. The zirconium salt contains seed crystals.
4. The method for producing a zirconia powder according to any one of 4 to 4. 6. The zirconium salt is Y, Ce, Ca, Ti.
The zirconia powder according to any one of claims 1 to 5, which is a compound of at least one element selected from the group consisting of and Mg, and which contains a compound that becomes an oxide of the element by firing, or an oxide of the element. Manufacturing method. 7. The method for producing a zirconia powder according to claim 1, wherein the zirconium salt contains an aluminum compound which becomes alumina by firing, or alumina. 8. A method for producing a zirconia powder, which comprises the following steps. Step 1: A step of calcining a zirconium salt to obtain a calcined product. Step 2: A step of firing the calcined product in an atmosphere containing hydrogen chloride. 9. The method for producing zirconia powder according to claim 8, wherein the calcination temperature is 400 to 700 ° C. 10. The method for producing a zirconia powder according to claim 8, wherein the zirconium salt is zirconium oxychloride. 11. The method for producing a zirconia powder according to claim 8, wherein the concentration of hydrogen chloride in the atmosphere containing hydrogen chloride is 1% by volume or more. 12. The method for producing a zirconia powder according to claim 8, wherein the firing temperature is in the range of 700 to 1100 ° C. 13. A calcined product containing seed crystals.
The method for producing a zirconia powder according to any one of 1. 14. The calcined product is (1) Y, Ce, Ca, Ti.
14. A compound of at least one element selected from the group consisting of: and Mg, which is a compound that becomes an oxide of the element by firing, or (2) contains an oxide of the element. The method for producing a zirconia powder according to any one of 1. 15. The method for producing zirconia powder according to claim 8, wherein the calcined product contains (1) an aluminum compound which becomes alumina by firing, or (2) alumina.