JPH0651568B2 - Method for producing fine zirconium oxide powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention is to solid-dissolve zirconium oxide with at least one metal component selected from magnesium, calcium and metal elements having a valence of 3 or more. And a method for producing a zirconium oxide fine powder comprising

Zirconium fine oxide powder, as a solid electrolyte for oxygen sensor for automotive exhaust gas for and blast furnaces, or _{Al 2 O 3, Si 3 N} 4, SiC, MgO · Al 2 O 3 ( spinel), 3Al ₂
For example, high strength and high toughness dispersion strengthened ceramics or dispersion strengthened alloys made by dispersing fine tetragonal ZrO ₂ particles in a ceramic such as O ₃・ 2SiO ₂ (mullite) or a metal such as Co-Ni alloy Used as a ceramic raw material.

It is strongly desired that the zirconium oxide-based powder is an ultrafine crystal having a primary particle size of several hundred Å or less and that it does not form strong secondary agglomerated particles. Takes a lot of time to generate the ultrafine particles of
Since expensive raw materials or equipment have to be used, the production cost is high and the expansion of demand is hindered.

<Prior art and problems> A general method for producing a fine zirconium oxide powder is an aqueous solution of a water-soluble zirconium salt and a metal element having a valence of 3 or more such as Ca, Mg and Y (referred to as a stabilizer). A mixed solution with an aqueous solution in which at least one kind is added in the form of a soluble compound such as an oxide or a salt and dissolved is precipitated as a sparingly soluble hydroxide in an alkali such as ammonia water, and washed with water.
After drying, it undergoes calcination and thermal decomposition at several hundreds of degrees Celsius. However, in this method, the salt of the starting material remains, and only coarse secondary coagulated particles having a wide particle size distribution are obtained, mechanical grinding is essential, and it is difficult to maintain high purity.

In recent years, various methods have been proposed for avoiding coarsening of particles and formation of strong secondary agglomerated particles at the time of drying and at the time of calcination pyrolysis, which are disadvantages of the above-mentioned production method. For example,
A precipitation slurry obtained from a mixed aqueous solution of a zirconium salt and a stabilizer salt is boiled under reflux for about 100 hours to form a colloidal sol, and then an organic solvent such as benzene, cyclohexane, n-octyl alcohol is added, and the mixture is heated and distilled by heating. There is a method of dehydrating and drying, and thermally decomposing the obtained fine particles of zirconium hydroxide. (JP-A-56-145118). However, as is clear from the above description, this method requires a long time for production, and since the production cost is high because an organic solvent is used, its use is limited.

Further, there is a method of drying and calcination of an amorphous sol produced by hydrolysis of a mixed alkoxide solution of zirconium and a stabilizer, but some agglomeration of particles is unavoidable and the raw material cost is extremely high.

Furthermore, as a method of producing crystalline fine particles in a solution, there is a method of heat-treating a mixed aqueous solution of a zirconium salt and a stabilizer salt under atmospheric pressure or hydrothermal pressure. As the atmospheric pressure method, a mixed aqueous solution of zirconium salt and a stabilizer salt (pH <2.0 at which zirconium hydroxide precipitates are not formed)
Hydrogen peroxide solution is added to the temperature range of 80 to 300 ° C.
Method of heat-treating (JP-A-58-79818)
There is.

However, this method also requires several days to obtain a practical amount of ZrO ₂ particles. Further, the hydrothermal pressurization method is not a practical method because the equipment cost is high because a pressure vessel is used.

<Means for Solving Problems> The present applicant has conducted various studies in order to solve the drawbacks of the known method for producing a zirconium oxide-based powder, and as a result, zirconium hydroxide was found to be contained in an alkaline aqueous solution having a pH of 12 or more. When forming a complex with hydrogen peroxide and dissolving it, and heat-treating this alkaline aqueous solution, hydrogen peroxide of the ligand is gradually decomposed and desorbed, and the conventional method is used even if crystalline ZrO ₂ ultrafine crystal particles do not exist. Based on the finding that crystalline ZrO ₂ ultrafine particles are formed in a shorter time than the atmospheric pressure precipitation method of crystalline zirconium oxide, the method for producing crystalline zirconium oxide fine powder is already submitted in Japanese Patent Application No. 60-111179. However, the present invention intends to apply the technique to a method for producing a zirconium oxide-based powder containing a stabilizer.

That is, the present invention relates to magnesium, calcium and 3
An aqueous solution containing a salt of at least one metal selected from metal elements having a valence of at least one and a salt of zirconium
After reacting with hydrogen peroxide in an alkaline aqueous solution having a pH of 12 or more to form a water-soluble zirconium ion hydrogen peroxide complex, heat treatment is performed at a temperature of 80 to 200 ° C. It is a manufacturing method.

The present invention will be described in more detail below.

Examples of the salt of the starting material used in the present invention include hydrochloride, nitrate, sulfate, acetate and the like. As the metal element having a valence of 3 or more, yttrium,
Examples include cerium, ytterbium, and scandium. In addition, the amount of stabilizer is MgO and CaO with respect to ZrO ₂ .
About 3 to 15 mol% and Y ₂ O ₃ etc. about 2 to 15 mol%.
Is appropriate.

Next, an alkaline agent and hydrogen peroxide are added to a mixed aqueous solution containing a zirconium salt and a stabilizer salt, and the mixture is reacted with hydrogen peroxide in an alkaline aqueous solution having a pH of 12 or more to dissolve the water-soluble zirconium ion. Form a hydrogen oxide complex.
The alkaline agent and hydrogen peroxide may be added in any order such as divided addition. The reaction temperature is usually room temperature. The metal component concentration in the mixed aqueous solution is not particularly limited, but from a practical point of view, it is suitable to be about 0.1 to 1.0 mol / min.

As the alkaline agent, any of ammonia water, NaOH, KOH, etc. may be used, but it can easily achieve a hydrogen ion concentration of pH = 12 or more which starts to dissolve when it becomes a hydrogen peroxide complex of zirconium ion, and it is a zirconium oxide type. Since it is subjected to a heat treatment when producing a fine powder, it is desirable that it is not volatile. In this case, if the alkali concentration is increased to, for example, pH ≧ 13.5, the decomposition and desorption rate of the hydrogen peroxide complex of zirconium ion will be significantly slowed down, so that the zirconium oxide fine particles having excellent crystallinity and dispersibility will be obtained. A powder can be produced. Moreover, since the effect of increasing the molar boiling point by the solute can be taken large, the heat treatment temperature of the hydrogen peroxide complex which is the next treatment can be raised, and the crystallinity and dispersibility can be further improved. Therefore, in the present invention, it is preferable to increase the alkali concentration.

As the hydrogen peroxide, it is desirable to use hydrogen peroxide solution, and the addition amount thereof is preferably equal to or more than the equimolar amount of zirconium in the solution in order to form a hydrogen peroxide complex of water-soluble zirconium ions.

The hydrogen peroxide complex obtained as described above is then heat treated. The heat treatment temperature is 80 to 200 ° C, preferably 90 to 140 ° C. If the temperature is lower than 80 ° C, it takes a long time to deposit the powder and it is not economically practical. On the other hand, if the temperature exceeds 200 ° C, the reaction time is shortened, but not only the fixed equipment cost such as equipment is increased. The produced powder is coarse and the particle size is not uniform. It is desirable that the reaction tank is sufficiently agitated in order to enhance the homogeneity of the reaction and to homogenize the obtained powder. When manufacturing in a temperature range exceeding 100 ° C., a pressure vessel (autoclave or the like) capable of hydrothermal pressurization is used as described in the prior art. In the method of the present invention, it is possible to process at a temperature condition of 200 ° C. or less, and the cost is lower than that of the conventional one in terms of the material of the pressure vessel used when manufacturing under pressure conditions, the pressure resistance and the like. It can be manufactured with equipment.

<Examples> Hereinafter, examples and comparative examples will be further described.

Example 1 zirconium oxychloride _{(ZrOCl 2 · 8H 2 O)} 80g, chloride yttrium _{(YCl 3 · 6H 2 O)} 6g was dissolved in pure water 300 meters, this aqueous solution of sodium hydroxide (concentration: 0.5 mol / liters) In addition, 70 m of commercially available hydrogen peroxide solution having a hydrogen peroxide concentration of 31% by weight was added with stirring. Then, an aqueous solution of sodium hydroxide having a concentration of 8 mol / liter 2
When 00 m was added and stirred, a pale yellow liquid containing a water-soluble zirconium ion hydrogen peroxide complex was obtained. The pH of this liquid is measured by Horiba's pH meter (model:
As a result of measurement using F-8L), the pH was 12.8.

This was heated under reflux at a temperature of 95 ° C. for 3 hours to obtain an emulsion slurry. This was washed with pure water, filtered, and dried at a temperature of 100 ° C. for 5 hours. As a result of X-ray diffraction of the obtained dried product, it was found to be tetragonal zirconium oxide fine powder.

1 g of this fine powder was added to 50 m of ethyl alcohol prepared by adding an appropriate amount of a phosphoric acid ester-based dispersant (trade name "Emphos PS-21A") and subjected to a dispersion treatment for 30 minutes by a commercially available ultrasonic cleaner. As a result of observing the dispersion state with a transmission electron microscope, the primary particles are ultrafine particles of about 200 Å, and most of the particles form aggregates of about 0.1 μm, which shows that they have very good dispersibility. It was

Comparative Example 1 When the reaction was carried out in the same manner as in Example 1 except that hydrogen peroxide solution was not added, viscous slurry containing precipitate particles was obtained. The pH of this liquid was measured by the same measuring method as in Example 1, and as a result, it was pH 12.6. Under reflux of the slurry,
Heat treatment was performed at a temperature of 95 ° C. for about 10 hours. The treated product was washed with pure water, filtered, and dried under hot air at a temperature of 100 ° C. for 5 hours.

As a result of X-ray diffraction of the obtained dried product, it was found to be an amorphous powder. When this powder was observed with a transmission electron microscope in the same manner as in Example 1, it was found to be aggregated particles of 1 to 10 μm.

Example 2 Using 80 g of zirconium oxychloride (ZrOCl ₂ .8H ₂ O) and 5 g of magnesium chloride (MgCl ₂ .6H ₂ O), the same procedure as in Example 1 was repeated to obtain a water-soluble zirconium ion hydrogen peroxide complex. A yellow liquid was obtained. The pH of this liquid was measured by the same measuring method as in Example 1, and as a result, it was pH 12.7. Fine powder was obtained by the same procedure as in Example 1 below. The powder properties obtained were good in dispersibility as in Example 1.

Example 3 80 g of zirconium oxychloride (ZrOCl ₂ .8H ₂ O) and 2 g of calcium carbonate were used to obtain a pale yellow liquid containing a water-soluble zirconium ion hydrogen peroxide complex by the same procedure as in Example 1. The pH of this liquid was measured by the same measuring method as in Example 1, and as a result, it was pH 12.8. Fine powder was obtained by the same procedure as in Example 1 below. The powder properties obtained were good in dispersibility as in Example 1.

Example 4 The pale yellow liquid containing the hydrogen peroxide complex of the water-soluble zirconium ion of Example 1 was subjected to heat treatment for 2 hours while being kept at 140 ° C. under stirring using an autoclave (manufactured by High Pressure Chemical Co., Ltd.) for oxidation. The zirconium formation reaction was advanced to obtain an emulsion slurry. After washing and filtering with pure water,
It was dried at 0 ° C. for 5 hours. The characteristics of the obtained powder are shown in Example 1.
Similar to the above, the dispersibility was good.

<Effects of the Invention> (1) By reacting hydrogen peroxide as in the present invention, a powder is produced in a shorter time (within 3 hours) as compared with the conventional heat treatment method under normal pressure or under hydrothermal pressure. can do.

(2) The production method of the present invention comprises an extremely simple unit operation, and since a high yield can be obtained in a short time, industrial mass production is possible, and its economic value is extremely high. That is, the raw material salt aqueous solution, the hydrogen peroxide solution, and the alkaline agent may be mixed and heat-treated. It is also possible to treat a concentrated solution of 1 mol / or more. Furthermore, it is sufficient to perform all operations in the same container, and a large amount of processing can be performed.

(3) The zirconium oxide-based fine powder obtained by the production method of the present invention has a uniform particle size and is composed of primary particles that do not substantially agglomerate even when dried by heating after washing / dehydrating, and have excellent dispersion. It has both sex and miscibility. Therefore, it is particularly useful as a raw material powder for dispersion strengthening ceramics and dispersion strengthening alloys, and further as a raw material powder for producing a high density sintered body.

Front page continuation (72) Inventor Shimada ▲ Sadayuki No. 2209 Aomi, Aomi-cho, Nishikubiki-gun, Niigata Prefecture Tokiko Nakata, Examiner, Aomi Plant, Denki Kagaku Kogyo Co., Ltd. (56) Reference JP-A-59-35029 A) JP-A-58-79818 (JP, A)

Claims (1)

[Claims] 1. An alkaline aqueous solution having a pH of 12 or more by adding hydrogen peroxide to an aqueous solution containing a salt of at least one metal selected from magnesium, calcium and a metal element having a valence of 3 or more and a zirconium salt. A method for producing a zirconium oxide-based fine powder, which comprises reacting in water to form a water-soluble zirconium ion hydrogen peroxide complex and then heat-treating at a temperature of 80 to 200 ° C.