JPS5969428A - Manufacture of ultrafine powder of zirconium oxide - Google Patents

Abstract

PURPOSE:To manufacture ultrafine powder of zirconium oxide in simple stages, by heating an alkaline aqueous soln. contg. zirconium carbonate under pressure, adding an org. solvent to the resulting zirconium oxide, removing water by distillation under heating, and carrying out drying. CONSTITUTION:An alkaline aqueous soln. contg. zirconium carbonate or a slightly acidic or alkaline soln. prepared by suspending or partially dissolving zirconium hydroxide in said aqueous soln. is reacted in an autoclave at >=130 deg.C, preferably about 170-220 deg.C under >=2kg/cm<2>, preferably about 5-40kg/cm<2> gauge pressure to form zirconium oxide. An org. solvent is added to the zirconium oxide, and water is removed by distillation under heating. The preferred org. solvent is xylene or the like having >=about 110 deg.C b.p. The solvent is separated after the distillation, and the residue is dried to obtain ultrafine powder of zirconium oxide having <=about 200Angstrom uniform particle size.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing ultrafine zirconium oxide powder, and TPY relates to a method for producing ultrafine zirconium oxide powder that can exhibit high strength after sintering into porcelain.

Zirconium oxide is being widely used in cutting tools, solid electrolytes, heat-resistant and wear-resistant parts, etc., and is also being used as a substitute for conventional materials in internal combustion engine mechanical parts, such as automobile engine head faces, piston caps, cylinder liners, etc. There is a lot of interest. If its properties as a porcelain material can be further improved, it is expected that even wider uses will be developed. Although it is desired to improve the properties of the conventionally used zirconium oxide porcelain in many respects, the most basic one is to improve the strength level after sintering.

The applicant has established a method for producing ultrafine zirconium oxide powder. This method can produce ultrafine orthorhombic-tetragonal mixed zirconium oxide powder having a very small particle size in the range of several + Therefore, there is great interest in MJJ as a method for producing zirconium oxide, which is suitable as a starting material for porcelain production. A dissolved slightly acidic or alkaline solution is used as the starting material, and this is heated to a temperature of 1
Zirconium oxide is directly produced by reacting at a temperature of 30°C or higher and a gauge pressure of 2kg/cm2 or higher. In this method, silconium oxide is produced through the following steps: neutralization of an acidic aqueous solution containing zirconium, precipitation of zirconium hydroxide, washing and filtration of the precipitate, drying of the resulting cake, and high-temperature roasting.
This method solves the problems that the number of steps is very large and the particle size of the obtained acid fE zirconium is coarse and the particle size distribution is wide.

Zirconium oxide obtained by the above method or Y
, 08, when mixed with stabilizers and other additives, higher levels of strength can be obtained than when using conventional coarse zirconium oxide powders.

Porcelain made of zirconium oxide powder is made by drying the powder,
It is produced via the steps of calcination, press forming and sintering at a temperature of 0-1000'C, and when additives such as Y2O3 are added, ball mill mixing is performed before calcination. As a result of a detailed study of these processes, it was found that strong clay could be obtained by adding an organic solvent to the ultrafine zirconium oxide powder obtained by the above method and dehydrating and drying it by heating distillation as a starting material. Served. , heating distillation using an organic solvent effectively suppresses the aggregation of primary particles of ultrafine zirconium oxide powder, and the fact that a thin film of organic solvent remains after heating distillation and the presence of decomposed carbon after sintering increases strength. It is assumed that they are connected.

Thus, the present invention provides the following steps: 1. After producing zirconium oxide according to the method described above, it is separated from the mother liquor. , provides a method for producing ultrafine zirconium oxide powder, which comprises adding an organic solvent and dehydrating and drying by heating distillation.

Zirconium carbonate (in a solution with pH 8-9), 5Zr
It exists in the form of O(Co8)i, which when heated under pressure directly produces zirconium oxide according to the following formula: HQZrO(Co,,) Q −) ZrO2+200
2 +l-120TIQZrO (COJs+ is unstable in the valve cylinder, so the above equation proceeds at a relatively low temperature, and the ZrO after decomposition
r0Q can uniformly have extremely small particle size. Based on the principle described above, we succeeded in directly producing zirconium oxide fine powder from zirconium carbonate.

The decomposition reaction proceeds even when zirconium hydroxide is mixed in an alkaline aqueous solution of zirconium carbonate. temperature is 1
The reaction will proceed at temperatures above 30°C, but generally at temperatures above 170°C.
A range of ˜220° C. is used. Pressure is gauge pressure 2k
g/c- or more, preferably 5-40! 7/cm2. The reaction is usually carried out for about 30 minutes to 3 hours while stirring is continued. pH and temperature of starting solution.

Although it depends on the power, force, etc., it is generally 200X or less, preferably (mainly 10 to 100X) zirconium oxide powder can be obtained.

After the zirconium oxide powder thus produced is separated from the mother liquor, an organic solvent is added thereto.

41 The use of a solvent with a boiling point of 110°C or higher is
Preferred for complete dehydration. This is because complete dehydration cannot be achieved unless the organic solvent has a boiling point higher than the boiling point of water. For example, xylene (b, p, 144°C
),) Luey (b, p, 110”C), hepknol (b, p, 176°C), nonyl alcohol (b, p
, 213°C) etc. are used. After sufficiently heated distillation, the final ultrafine zirconium oxide powder is obtained by cooling, separating the organic solvent, and drying.

The resulting powder is used alone or with Y, 08 and other additives as a starting material for the production of porcelain. The zirconium oxide produced by this method is 2
Despite being an ultrafine powder with a particle size of less than 0.00 s, no agglomeration of secondary particles occurs during calcination. This is because water, which causes secondary particle aggregation, is completely eliminated.

The highly uniform ultrafine powder prepared by the above method is combined with the organic solvent treatment, and when this powder is molded into porcelain, the valve barrel exhibits 'Ptr °C strength. 2-3, 5 Mo#
When cold pressed and sintered with addition of % Y2O27. By adding an optimum strength of Oi<g/m2 or more and around 3 mol%, it is possible to develop a bending strength as high as 130 kg7m2.

The same powder treated with organic solvent is 2 times better than the one without organic solvent treatment.
Shows 0-30% higher strength level. Therefore, the zirconium oxide TG (TY powder) produced according to the present invention exhibits greater durability and stability in conventional cooling, and also opens the door to new cooling applications where zirconium oxide could not be used due to lack of strength. For example, R1 makes it possible to use zirconium oxide in internal combustion engine parts, high-performance cutting tools, etc. mentioned above.

Example 1 1 liter of a weakly alkaline aqueous solution containing 100/l of zirconium carbonate, 50 l/l of Glauber's salt and 5 q/l of sodium carbonate was prepared in an autoclave with a capacity of about 24 kg to about 30 kg.
Zirconium oxide was produced by reacting for 60 hours with stirring at 11 g/c+n2) and a temperature of 205°C. After separating the generated zirconium oxide from the mother liquor, nonyl alcohol was added and distilled. boiling point is 1
Distillation was stopped when the temperature reached 15°C, and the mixture was cooled. After cooling, the organic solvent was separated and dried at 95°C. The obtained zirconium oxide was an ultrafine powder with an average size of 100 s.

To see the strength of porcelain obtained using this powder,
Blend a mixed powder with 3 mol% Y and 108 added, SOO''
After calcining at C and crushing 5. The specimen was press-molded into a specimen of my+X5 dimensions x 60 bars, and then sintered for 2 hours, and the bending strength of the specimen was measured. For comparison purposes, we used commercially available coarse zirconium oxide with a particle size of 500λ (organic solvent treatment) and 100-year-old zirconium oxide prepared the day before [2], except that it was not treated with an organic solvent. A similar specimen was prepared using the same method. The results are shown in the table below.

Example 2 Aqueous solution 5e containing 509 g/l of zirconium carbonate, 25 g/e of mirabilite and 25 g/l of soda carbonate was added in a volume of 10 g/l.
The reaction was carried out in an autoclave at a pressure of about 25 kg 7 cm 2 and a temperature of 200°C for 60 minutes with stirring. The produced zirconium oxide was heated and distilled using a heptatool. When the bending strength of the obtained powder was measured in the same manner as in Example 1, it showed a value of 128 ky/2.

In this way, the combination of the 41-machine treatment and the ultrafine powder makes it possible to produce porcelain with a very high level of strength 1.

Claims (1)

[Claims] 1) Heat an alkaline aqueous solution containing zirconium carbonate or a slightly acidic or alkaline solution in which zirconium hydroxide is suspended or partially dissolved in a pressure-resistant container at a temperature of 130°C or higher and a gauge pressure of 2kg/cm2 or higher. A method for producing ultrafine zirconium oxide powder, which comprises producing zirconium oxide by reacting under the following conditions, and then adding an organic solvent to the produced zirconium oxide and dehydrating and drying it by heating distillation.