JPS638220A - Production of zirconium oxide powder - Google Patents

Abstract

PURPOSE:To readily and industrially obtain ZrO2 powder having a narrow viscosity distribution, by adding an alkali (carbonate) and Zr(OH)4 as a seed to a specific water-soluble metal salt, drying and firing the resultant deposit. CONSTITUTION:A water-soluble Zr compound alone or together with one or more rare earth elements selected Y, Ce, Pr, Nd, Sm, Eu, Dy and Yb and one or more alkaline earth metals selected from Mg, Ca and Sr are dissolved in water to give amounts of the rare earth elements and alkaline earth metals satisfying <=15mol% metal oxides based on ZrO2 expressed in terms of oxides of the composition after firing and give a metal salt solution. An alkali (carbonate) is then added to the resultant solution to provide a neutralized solution (A). Zr(OH)4 obtained from a solution of the same composition as the solution (A) as a seed in an amount of 1-10wt% based on the amount of deposit formed in the solution is added to the solution (A) to afford deposited precipitates (B) of the Zr(OH)4. The component (B) is then filtered, dried and fired.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for producing zirconium oxide powder, and more specifically, in precipitating zirconium hydroxide by a neutralization method, a small amount of f-molecules is The present invention relates to a method for producing zirconium oxide powder characterized by adding zirconium hydroxide.

<Prior art> In recent years, zirconium oxide powder has come to be used in a wide range of fields as high-strength, high-toughness partially stabilized zirconium oxide molded bodies and fully stabilized zirconia molded bodies as oxygen sensors, and therefore has been used in various production methods. Methods are being considered. The method for producing these zirconium oxide powders is as follows: 1. Add compounds such as yttrium, magnesium, cerium, and calcium as stabilizers to water-soluble zirconium hydrate, then neutralize with alkali, filter, and wash with water. There are two methods: drying and firing, and (2) adding a stabilizer to zirconium oxychloride or zirconium alkoxide and drying and firing a hydroxide obtained by hydrolyzing the mixture.

<Problems to be solved by the invention> Method (2) has the advantage that the raw materials are cheaper and can be produced on an industrial scale compared to the hydrolysis method (2), but the zirconium hydroxide does not contain a stabilizer. Gel mainly composed of zirconium hydroxide, which is a precipitate, probably because it is not homogeneously dispersed (
Even if zirconium hydroxide (hereinafter simply referred to as zirconium hydroxide) is dried and calcined, zirconium oxide powder having a homogeneous composition and particle size cannot be obtained.

Measures to Solve the Problems> Under these circumstances, the inventors of Yokigi conducted intensive studies to solve the above-mentioned drawbacks of the neutralization method, and found that the pH of the aqueous solution containing zirconium was approximately 4 to 5. The viscosity of the aqueous solution increases rapidly in the vicinity, making it difficult to stir the entire solution.
It has been found that when the pH exceeds about 5, a phenomenon occurs in which the solution viscosity decreases again. However, the temporary increase in the viscosity of the solution during the neutralization process prevents the homogeneous precipitation of zirconium hydroxide and furthermore the homogeneous precipitation of the stabilizer on the surface of the zirconium hydrate or near the particles, resulting in We presume that this is the reason why it is not possible to obtain zirconium oxide powder with a homogeneous composition and particle size, and we have found a method that minimizes viscosity increase during neutralization treatment and allows for uniform stirring of the precipitation reaction system. As a result of repeated research, we have found that if zirconium hydroxide, which precipitates into an aqueous solution, is added to the aqueous solution during the neutralization process, the neutralization process can be carried out without causing almost any increase in viscosity even at a pH of 4 to 5. The present inventors have discovered that the present invention can be obtained and completed the present invention.

That is, the present invention combines a water-soluble zirconium compound alone, or a water-soluble zirconium compound and at least one water-soluble metal salt of a rare earth or alkaline earth metal with an alkali or an alkali carbonate, and a mixture of about 1 to about 10% by weight based on the precipitate. zirconium hydroxide is added as a seed to form a precipitate, and the precipitate obtained is then filtered and washed with water.
The present invention provides a method for producing zirconium oxide powder, which is characterized by drying and firing.

The method of the present invention will be explained in more detail below.

The type of water-soluble zirconium compound used in carrying out the present invention is not particularly limited as long as it forms zirconium oxide after firing, but for example, zirconium oxychloride, zirconium sulfate, basic zirconium carbonate, or a mixture thereof. etc.

On the other hand, the rare earth and/or alkaline earth metals may be those that form oxides of the respective metals after firing, and specifically include yttrium, cerium, praseodymium,
Rare earths such as neodymium, samarium, europium, dysprosium, interbium, alkaline earth metals such as magnesium, calcium and strontium are chlorides, nitrates, sulfates or acetates and alkali metal salts,
Furthermore, they are used in the form of a mixture.

The mixing ratio of rare earth and alkaline earth metals to the water-soluble zirconium compound is not unambiguous as it varies depending on the metal to be applied and the purpose of the zirconium oxide powder to be produced, but it is , is used within 15 mol% as a metal oxide.

A predetermined amount of a water-soluble metal salt as a stabilizer is added to a water-soluble zirconium compound or a water-soluble zirconium compound, and the solution is thoroughly stirred and mixed. Next, sodium hydroxide, potassium hydroxide, and ammonium hydroxide are added to the water-soluble zirconium compound according to a known method. or an alkali carbonate such as sodium carbonate, sodium hydrogen carbonate, ammonium carbonate, etc., and zirconium hydroxide, which is expected to be precipitated as seeds, are added and stirred to gradually neutralize and precipitate.

The feature of the method of the present invention is that during the neutralization treatment, 1 to 10% by weight of zirconium hydroxide is added to the precipitated amount as seeds, and this results in the presence of zirconium hydroxide in the amount of 1 to 10% by weight based on the amount of precipitated seeds. is a specific Op in the neutralization precipitation process.
Countless tiny zirconium hydroxide crystals are generated in the H region,
These crystals rapidly form a three-dimensional network structure, and when water is taken into the network, a significant increase in viscosity occurs, but if seeds are present, the seeds suppress the formation of minute crystals. Therefore, it is presumed that abnormal viscosity increase can be prevented.

The composition of the zirconium hydroxide added as seeds is not particularly limited as long as it has the same composition as the desired product, but it is preferably precipitated by a neutralization method from a solution with the same composition as the solution added as seeds. It is better to use zirconium hydroxide.

When carrying out the method of the present invention, zirconium hydroxide as seeds is added in an amount of about 1 to 10% by weight based on the expected amount of neutralized precipitation.

If the amount of seeds added is less than 1% by weight, the effect of suppressing the rapid increase in viscosity will be small, and if it exceeds 10% by weight, there will be no commensurate effect on the amount added, which is rather economically unfavorable.

When adding seed zirconium hydroxide during the neutralization process, there are two methods: by dispersing it in the solution for neutralization precipitation before the start of neutralization, or by dispersing it in advance in a solution such as an alkali for neutralization. However, any method may be applied, and it is of course possible to combine these methods.

The zirconium hydroxide thus obtained through neutralization and precipitation is filtered by a known method, separated from the solution, and then washed with water.
It is dried and then fired at a temperature of 600-1300°C.

If the firing temperature is lower than 600°C, zirconium hydroxide cannot be completely converted to zirconium oxide powder;
If the temperature exceeds 0°C, the particles of the zirconium oxide powder will become coarse, which is not preferable.

As described in detail above, the present invention causes an increase in viscosity by an extremely simple method of adding zirconium hydroxide as a seed to an aqueous solution to be subjected to the neutralization treatment when zirconium hydroxide is precipitated by a conventionally known neutralization method. This makes it possible to obtain zirconium hydroxide with a homogeneous particle size and a narrow particle size distribution without any process, and its industrial value is enormous.

<Example> The method of the present invention will be explained in more detail with reference to Examples below.
The present invention is not limited to these examples.

Example 1 After dissolving 500 g of zirconium oxychloride (in terms of Zr○2) and 50 g of yttrium chloride in 101 g of pure water in a 201 polyethylene container, an aqueous solution of zirconium oxychloride and yttrium chloride having the same composition as above was added to this. 10% ammonia water (31) in which 25 g of zirconium hydroxide obtained by the neutralization method was dispersed
It was added at a rate of cc/min. Figure 1 shows the change in viscosity of the aqueous solution during this neutralized coprecipitation.

Furthermore, for comparison, a neutralization treatment was carried out in exactly the same manner as in the above method except that zirconium hydroxide as seeds was not added to the ammonia water for neutralization.

FIG. 1 also shows the change in the viscosity of the water i8 liquid during this neutralization.

As is clear from No. 10 (it can be seen that the viscosity increase during the neutralization treatment is smaller in those neutralized with an alkaline solution containing zirconium hydroxide seeds than in those to which seeds are not added and dispersed.

In addition, zirconium hydroxide precipitated by the above method is filtered,
After washing with water, drying and baking at a temperature of 1000'c for 2 hours,
It was pulverized in a vibrating mill for 2 hours.

The zirconium oxide powder obtained in this way is used as a seed additive for particles with an average particle size of 0.6μ, +2μ or more.
% by weight, and the average particle size of the additive-free product is 0.7μ, +2
Particles larger than μ accounted for 20% by weight.

[Brief explanation of the drawing]

Figure 1 shows the i8i! zirconium hydroxide precipitation reaction system in which a stabilizer is dispersed during neutralization treatment. In the figure, O indicates the case where seed zirconium hydroxide is added, and * indicates the case where no seed zirconium hydroxide is added. Figure 1 0 0.20.40.60.8 10 Neutralized coprecipitation amount [Ratio]

Claims (1)

[Scope of Claims] 1) A water-soluble zirconium compound alone, or a water-soluble zirconium compound and at least one water-soluble metal salt of a rare earth metal or an alkaline earth metal, and an alkali or alkali carbonate, with a concentration of 1 to 10% based on the precipitate. 1. A method for producing zirconium oxide powder, which comprises adding parts by weight of zirconium hydroxide as seeds to form a precipitate, and then filtering the obtained precipitate, washing with water, drying, and calcining. 2) Rare earths are yttrium, cerium, praseodymium,
The method for producing zirconium oxide powder according to claim 1, wherein the powder is at least one selected from neodymium, samarium, europium, dysprosium, and ytterbium. 3) The method for producing zirconium oxide powder according to claim 1, wherein the alkaline earth metal is at least one selected from magnesium, calcium, and strontium. 4) The amount of at least one water-soluble metal salt of a rare earth or alkaline earth metal added to the water-soluble zirconium compound is within 15 mol% as a metal oxide based on the zirconium oxide in the composition after firing. A method for producing zirconium oxide powder according to claim 1, characterized in that: 5) The method for producing zirconium oxide powder according to claim 1, characterized in that the zirconium hydroxide used as the seeds is zirconium hydroxide precipitated from a solution having the same composition as the solution to which the seeds are added.