JPH0524843A - Production of hydrated zirconia sol and zirconia powder - Google Patents

Abstract

PURPOSE:To produce a hydrated zirconia sol-having large particle diameter and small crystal size and to produce zirconia powder having excellent moldability and highly compatible with a stabilizing agent such as yttria by using the hydrated zirconia sol. CONSTITUTION:Hydrated zirconia sol is produced by heat-treating a suspension containing zirconium hydroxide, hydrochloric acid and an inorganic chloride while controlling the hydrochloric acid concentration to 0.1-0.8mol/l and the chlorine ion concentration to >=1mol/l. Zirconia powder can be produced by calcining the hydrated zirconia sol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrated zirconia sol used as a raw material for producing a zirconia thin film, a zirconia-based ceramic raw material powder, and a method for producing a zirconia powder.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a hydrated zirconia sol, a method for obtaining a hydrated zirconia sol by hydrothermally treating an aqueous zirconium salt solution under pressure at 120 to 300 ° C. (US Pat. No. 2,984,628) Aqueous suspension containing zirconium oxide to pH 1
Method of heating in an acidic atmosphere of ˜5.5 (Japanese Patent Laid-Open No. 64-64-
After the hydrolysis treatment of the zirconium salt aqueous solution,
A method of separating particles having a thickness of 1 to 0.3 μm by a sedimentation method or the like (JP-A-58-217430) is known.

[0003]

According to the studies made by the present inventors, the smaller the crystallites of the hydrated zirconia sol, the more yttria, calcia, magnesia, which is commonly used in the production of the sol and zirconia-based ceramics, When a zirconia powder was obtained by mixing with a stabilizer such as ceria and calcining to obtain a zirconia powder, the solid solution reaction was accelerated, and in particular, it was obtained by heat treatment under the condition that the chloride ion concentration was 1 mol / l or more. The crystallites of the hydrated zirconia sol are 4 nm or less, and when the crystallites of the hydrated zirconia sol are 4 nm or less, the effect becomes remarkable. The hydrated zirconia sol preferably has an average particle size of 0.1 μm or more and a particle size range of 0.05 to 0.5 μm, and when the average particle size is smaller than 0.1 μm, the sol is formed. When the zirconia powder is calcined to obtain a zirconia powder, a strong agglomerate is formed, and a zirconia powder having poor formability and sintered body properties is obtained.

By the way, the hydrated zirconia sol obtained by the methods (1) and (2) has a particle size smaller than 0.05 μm, and as described above, strong agglomeration occurs during calcination, and the obtained zirconia powder is molded. Hard to do,
It is not suitable for ceramic raw material powder. Further, since it is a hydrothermal synthesis method, it is not suitable for industrial mass production and is not practical. The hydrated zirconia sol obtained by the method of 1 has a crystallite larger than 4 nm, and as described above,
It is considered that it is difficult to form a solid solution with the stabilizer. Furthermore, particles having a particle size of 0.1 to 0.3 μm must be centrifuged, and in any case industrialization is difficult and not a practical method.

The present invention is a method for producing a hydrated zirconia sol having a large particle size and a small crystallite, in which the drawbacks of the conventional method are eliminated, and the hydrated zirconia sol is used for molding. It is an object of the present invention to provide a method capable of producing a zirconia powder which has good properties and which is in solid solution with a stabilizer such as yttria by a simple process.

[0006]

According to the present invention, a hydrochloric acid concentration of a suspension containing zirconium hydroxide, hydrochloric acid and an inorganic chloride is 0.1 to 0.8 mol / l and a chloride ion concentration is 1 mol. The present invention is directed to a method for producing a hydrated zirconia sol, which is characterized in that heat treatment is performed at a controlled flow rate of 1 / l or more. The present invention will be described in more detail below.

The hydrated zirconia sol obtained by the present invention is
The average particle size is 0.1 μm or more and 4 nm or less, and the average particle size can be obtained by observing the particle size with an electron microscope or measuring the particle size with a particle size distribution measuring device, such as a photon correlation method.

In the present invention, when a suspension containing zirconium hydroxide, hydrochloric acid and an inorganic chloride is heated, a hydrated zirconia sol is obtained. At this time, the concentration of hydrochloric acid in the suspension is 0.1 or more. It should be set to 8 mol / l or less, and the chlorine ion concentration should be set to 1 mol / l or more. Hydrochloric acid concentration is less than 0.1 mol / l or 0.8 m
When it is larger than ol / l, the average particle size of the obtained hydrated zirconia sol is smaller than 0.1 μm. Further, when the chloride ion concentration is lower than 1 mol / l, the crystallite diameter of the hydrated zirconia sol produced is larger than 4 nm. Further, the chlorine ion concentration is preferably 1 or more and 3 mol / l or less, and when the chlorine ion concentration is more than 3 mol / l, the reaction time becomes long and the production efficiency is lowered, which is not preferable. The slurry concentration of zirconium hydroxide is
Any concentration may be set as long as it is in a slurry state, but preferably 0.05 to 2.0 mol / l,
More preferable slurry concentration is 0.1 to 1.5 mo.
1 / l. If the slurry concentration is less than 0.05 mol / l, it is not suitable for industrial mass production, and 2.0 mol / l
If it is larger than 1, the viscosity of the slurry becomes high, and it becomes difficult to set reaction conditions.

Various methods can be selected as a method for producing zirconium hydroxide used in the present invention.
Zirconium hydroxide can be obtained by neutralizing a water-soluble aqueous zirconium salt solution with an alkali. As the water-soluble zirconium salt used here, zirconium oxychloride, zirconium nitrate, zirconium sulfate,
Examples of the alkali include zirconium chloride and the like, and examples of the alkali include ammonia, sodium hydroxide, potassium hydroxide and the like, but in addition to these, a compound such as urea which becomes basic when thermally decomposed may be used.

The inorganic chloride mixed in the present invention includes ammonium chloride, metal chlorides such as sodium chloride,
Examples thereof include chlorides of alkali metals and alkaline earth metals such as calcium chloride, aluminum chloride, zirconium oxychloride, zirconyl chloride, yttrium chloride, cerium chloride and the like.

The mixture slurry of zirconium hydroxide, hydrochloric acid and inorganic chloride prepared above is heated, and the heating temperature is preferably 80 ° C. or higher and 150 ° C. or lower, more preferably 90 ° C. or higher. It should be below the temperature. When the reaction temperature is higher than 150 ° C., the crystallites of hydrated zirconia are larger than 4 nm and the average particle size is smaller than 0.1 μm, the desired hydrated zirconia sol cannot be produced, and further hydrothermal Since it is a synthetic method, it becomes difficult to mass-produce industrially, which makes it impractical. When the reaction temperature is lower than 80 ° C., it takes a long time to complete the hydrolysis reaction, so that the production efficiency decreases. Also,
The reaction time is about 10 to 150 hours, depending on the reaction temperature.

In the present invention, the hydrated zirconia sol suspension obtained above is dried and then calcined to produce zirconia powder. At this time, in the case of producing a zirconia powder in which a stabilizer is in solid solution, a stabilizer, for example, a compound such as Y, Ca, Mg or Ce is added to a suspension of hydrated zirconia sol and dried. Alternatively, it may be added in advance when the hydrated zirconia sol is produced.

[0013]

[Function] It is not clear why the crystallites and the average particle size of the hydrated zirconia sol depend on the concentrations of hydrochloric acid and inorganic chloride in the suspension containing zirconium hydroxide, hydrochloric acid and inorganic chloride, but the obtained water Analyzing the structure of the zirconia sol, the primary particles with good crystallinity are composed of secondary particles, and the chlorine ions of the inorganic chloride in the suspension are
It is considered to be a factor that reduces the primary particles of hydrated zirconia formed during the reaction, and the concentration of hydrochloric acid affects the particle size of the secondary particles because it acts on the cohesive bonding reaction of the primary particles. It is presumed to be a thing.

[0014]

As described above, according to the present invention,
A hydrated zirconia sol having a large particle size and a small crystallite can be produced. Therefore, by using the hydrated zirconia sol, the moldability is good, and the zirconia powder is well in solid solution with a stabilizer such as yttria. Can be manufactured.

The hydrated zirconia sol of crystallites having an average particle size of 0.1 μm or more and 4 nm or less obtained by the present invention depends on zirconium hydroxide, hydrochloric acid and chloride ion concentration. The sol particle size and the crystallite can be controlled by appropriately setting so as to be controlled within the range limited by the present invention.

[0016]

EXAMPLES The present invention will be specifically described below with reference to examples. Example 1 Aqueous ammonia was added to 1 liter of 0.4 mol / l zirconium oxychloride to prepare zirconium hydroxide. After filtering and washing this zirconium hydroxide with water, 1
mol / l hydrochloric acid 0.5 liter, sodium chloride 35
g, and then distilled water to give a zirconium hydroxide slurry concentration of 0.4 mol / l and hydrochloric acid concentration of 0.5.
A mixture slurry of mol / l and sodium chloride 0.6 mol / l was prepared. While stirring this raw material liquid, the reaction was performed at the boiling temperature for 100 hours. The obtained hydrated zirconia sol had a crystallite size by powder X-ray diffraction of about 3.7 nm, and an average particle size by a photon correlation method of 0.23 μm.

4.85 g of yttrium chloride was added to the suspension of the hydrated zirconia sol obtained above, dried, and then calcined at each temperature. When Raman spectrum was measured to examine the solid solubility of the obtained zirconia powder,
Tetragonal crystals were observed at 500 ° C., and monoclinic crystals were slightly present.

Example 2 Example 1 was repeated except that 32 g of ammonium chloride was added. The obtained hydrated zirconia sol had a crystallite diameter measured by powder X-ray diffraction of about 3.7 nm, and an average particle diameter measured by a photon correlation method was 0.25 μm.

Example 3 Zirconium hydroxide was synthesized in the same manner as in Example 1,
Zirconium hydroxide slurry concentration 0.8 mol / l,
Hydrochloric acid concentration 0.7 mol / l, sodium chloride 0.5 mo
A 1 / l mixture slurry was prepared. While stirring this raw material liquid, a reaction was carried out at a boiling temperature for 130 hours. The obtained hydrated zirconia sol had a crystallite size by powder X-ray diffraction of about 3.2 nm, and an average particle size by a photon correlation method of 0.
It was 11 μm.

Example 4 Zirconium hydroxide was synthesized in the same manner as in Example 1,
Zirconium hydroxide slurry concentration 0.8 mol / l,
Hydrochloric acid concentration 0.7 mol / l, ammonium chloride 0.5 m
An ol / l mixture slurry was prepared. While stirring this raw material liquid, a reaction was carried out at a boiling temperature for 130 hours. The obtained hydrated zirconia sol had a crystallite size by powder X-ray diffraction of about 3.4 nm and an average particle size by photon correlation method of 0.12 μm.

Example 5 Zirconium hydroxide was synthesized in the same manner as in Example 1,
Zirconium hydroxide slurry concentration 0.2 mol / l,
Hydrochloric acid concentration 0.2 mol / l, sodium chloride 1.3 mo
A 1 / l mixture slurry was prepared. While stirring this raw material liquid, the reaction was performed at the boiling temperature for 100 hours.

The obtained hydrated zirconia sol had a crystallite size by powder X-ray diffraction of about 3.5 nm and an average particle size by photon correlation method of 0.13 μm.

Example 6 A slurry solution of zirconium hydroxide was prepared by adding 0.8 liter of 1 mol / l ammonia water to 1 liter of 0.4 mol / l zirconium oxychloride, and 1 mol / l hydrochloric acid was added to this slurry solution. 1 liter, 80 g of ammonium chloride was added. While stirring this raw material liquid,
The reaction was carried out at the boiling temperature for 100 hours. The crystallite diameter of the obtained hydrated zirconia sol was about 3.6 n as determined by powder X-ray diffraction.
m, and the average particle diameter by the photon correlation method was 0.21 μm.

Comparative Example 1 Zirconium hydroxide was synthesized in the same manner as in Example 1,
Zirconium hydroxide slurry concentration 0.4 mol / l,
A mixture slurry having a hydrochloric acid concentration of 0.02 mol / l was prepared. While stirring this raw material liquid, the reaction was performed at the boiling temperature for 100 hours.

The obtained hydrated zirconia sol had a crystallite diameter of 6.0 nm as determined by powder X-ray diffraction, and an average particle diameter of 0.03 μm as determined by the photon correlation method. To the suspension of hydrated zirconia sol obtained above, yttrium chloride 4.8
After adding 5 g and drying, it was calcined at each temperature. When Raman spectrum was measured to examine the solid solubility of the obtained zirconia powder, a few tetragonal crystals were observed at 600 ° C.

Comparative Example 2 Zirconium hydroxide was synthesized in the same manner as in Example 1,
Zirconium hydroxide slurry concentration 0.4 mol / l,
A mixture slurry having a hydrochloric acid concentration of 2.0 mol / l was prepared. While stirring this raw material liquid, the reaction was performed at the boiling temperature for 200 hours.

The average particle size of the obtained hydrated zirconia sol measured by the photon correlation method was 0.02 μm.

Claims (2)

[Claims] 1. A hydrochloric acid concentration of a suspension containing zirconium hydroxide, hydrochloric acid and an inorganic chloride is 0.1 or more and 0.8 mol / min.
A method for producing a hydrated zirconia sol, characterized in that the heat treatment is carried out at a concentration of 1 or less and a chlorine ion concentration of 1 mol / l or more. 2. A method for producing zirconia powder, which comprises drying a suspension of the hydrated zirconia sol according to claim 1 and then calcining the suspension.