JPS60103033A - Manufacture of zirconia-base hyperfine powder - Google Patents

Abstract

PURPOSE:To manufacture the titled hyperfine powder having high crystallizability at a relatively low temp. in a short time by adding a nitrogen compound which generates ammonia by decomposition to an aqueous soln. contg. a zirconium salt and by treating the soln. in an autoclave. CONSTITUTION:A compound which generates ammonia by decomposition such as urea or cyanate is added to an aqueous soln. of a zirconium salt such as zirconium oxychloride or an aqueous soln. contg. a zirconium salt and a salt of a desired metal such as Mg, Ca or Y which provides high toughness or stability, and the soln. is treated in an autoclave to manufacture the titled hyperfine powder having a uniform particle size and causing no coagulation. Since unlike a conventional slow reaction a rapid reaction is carried out by the autoclave treatment with the nitrogen compound which generates ammonia by decomposition, the titled hyperfine powder having high crystallizability can be synthesized at a relatively low temp. in a short time, thus, the manufacturing cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing ultrafine zirconia powder, which is attracting attention as a raw material for high-strength, high-toughness ceramics.

Zirconia has a high melting point and excellent corrosion resistance, so it has been widely used as a refractory material for steel manufacturing.
Furthermore, in recent years, high-strength, high-toughness zirconia with new properties has been developed, and it is expected to become one of the engineering ceramics that will continue to develop significantly in the future.

As is well known, in order to obtain high-strength, high-toughness zirconia, it is important to accurately control the fine NuI Mat structure of luconia ceramics. Ultrafine zirconia powder is considered to be safe.Therefore, in the production of ultrafine zirconia powder, many methods (tlf death) have been carried out, and by the time there was a method for completely mechanically refining zirconia powder - ，
Co-precipitation by adding ammonia etc. to a solution containing zirconium salt and metal fence τ? The method of completely calcining it is being debated.

I ran into a few problems.

Therefore, the inventors of the present invention conducted an F-research experiment on each building.

Aqueous zirconium salt solutions or zirconium salts and salts of desired metals, such as magnesium, calcium, yttrium, etc., exhibit high toughness.

In an aqueous solution containing a salt of fluorophore to stabilize it.

Unlike conventional methods, nitrogen generates ammonia when decomposed? By adding compounds (for example, urea, cyanate, etc.) and treating the entire product in an autoclave, we succeeded in producing Zirco-based ultrafine powder with a uniform particle size without agglomeration.

In this method, instead of 5 reactions τ as in the conventional method, which are heated slowly for 1 minute, a crab compound τ that produces % ammonia is used, and the reaction is performed at a breath rate by autoclaving, so it has good crystallinity. Zirconia fine powder can be synthesized at a relatively low temperature and in a short time, making it possible to reduce installation costs, and its industrial value is extremely great.

Examples of the present invention will be described below, but it goes without saying that the present invention is not limited to the examples illustrated here.

Example 1 Zirconium oxychloride 3 in 1.000 tnl of pure water
22 tons? Containing f is 5 by adding urea 702 to the solution and dissolving it.
A raw material solution for synthesis was prepared, and 750 liters of this raw material bath liquid for synthesis was subjected to autoclave treatment under the following conditions using an autoclave processing apparatus G (high temperature and high pressure vessel) having a volume of 1000 m#.

Autoclave processing conditions Filling rate: 75°C Temperature: 250°C Processing time: 12 hours The precipitate produced by Kamiguchi's treatment was repeatedly dehydrated and washed using a centrifugal separator and Super Shinba Dispersion MK, and then washed with water and ethanol. The mixture was replaced with 120° C. and dried for 12 hours to obtain zirconia fine powder 751.

According to X-Iwao diffraction, the powder thus obtained is square zirconia with very good crystallinity.

The average crystallite diameter measured by the Schucy method was 8nI11, which was extremely fine.

Furthermore, the particle size was uniform when observed using a transmission electron spectroscope.
It was also confirmed that there was little amount of X millet.

Example 2 Urea 7 (1') was added and dissolved in an aqueous solution containing 307 v of zirconium oxychloride and 189 yttrium chloride in 1,000 liters of pure water to create a synthetic solution, which was then autoclaved to perform the following reaction in AAIii. Autoclaved under the following conditions.

Autoclave treatment conditions Filling rate: 80% Temperature: 200'C Treatment time: 24 hours Precipitate formed by the above treatment) J! 73f of zirconia-based fine powder recovered in the same manner as in Example 1 and containing 1% of ittria k 3 mo as a solid solution. 11-'lυ. The obtained powder is cubic zirconia with good crystallinity.

The average crystallite diameter tilOn was very small, and the particle diameter was uniform and there was little aggregation.

This powder was subjected to -axis molding at a molding pressure of i t o n /crA and then sintered at 1500° C. for 2 hours, resulting in a dense sintered body, which was sintered to 98% of its theoretical density.

Also, from electron microscopy observation of the fractured surface of the sintered body.

The average particle size is 0.3 ttm, which is fine and has a uniform particle size, 4 x #3! The diffraction results confirmed that it was composed only of square solid baths.

As explained above, the zirconia fine powder t, i fine I411 according to the present invention has a uniform particle size without agglomeration, has good sinterability, and is considered to be widely applicable to high strength and high toughness raw material powder for steel.

It should be noted that the powder obtained in Example 1 of M11 was composed only of square-shaped objects, and in Example 2 (
The powder obtained in Example 1 is composed only of cubic-shaped powder, but by calcining the fine powder obtained by autoclaving using a known method, monoclinic-shaped powder can be obtained from the powder shown in Example 1. Also, from the material shown in Example 2, a square shaped material with a thin nose can be easily obtained.

This is the second invention.

Patent applicant: Chichibu Cement Co., Ltd. Agent: Osamu Hattori - Procedural amendment (voluntary) April 5, 1980 11'', 11゛ Commissioner of the Office of the Chief Justice Waka Iriwa Failure 1, Indication of the case 1982 Year 1 Samurai Juice F m m203722 No. 2,
Title of the invention 3, #1 iTE't'l-6 person'ru"=u"Relationship with 41 hazardous methods for producing yarn ultrafine powder 0 71. +-Permission P1+ person.

, jl + Kyoi,! Kanoyo [H Zai Marunouchi-chome 4-6
No.m Z (fsat) 1-"2f2p',=zi%'
! r, HIsI'E Chichibu Cement Co., Ltd. 4, Agent (1) I would like to correct the "square type" on page 4, line 19 of the specification to "F-type".

(2) On page 6 of the specification, lines 14 to 15, “To the main block
1. From now on, the solution is [King J, ll yarn) 1 (ll
I would like to correct it as “power/ra”.

Claims (2)

[Claims] (1) A zirconium salt aqueous solution or a water bath solution containing a zirconium salt and a desired metal salt is completely saturated with nitrogen compounds that generate ammonia when decomposed. A method for producing ultrafine zirconia powder, which is characterized by autoclave treatment. (2) Add a zirconium salt aqueous solution or an aqueous solution containing a zirconium salt and a desired metal salt to a nitrogen compound that completely generates ammonia when the mixture is allowed to cool, completely autoclave it, dehydrate and dry it, and calcinate it. A method for producing ultrafine zirconia powder that has all the following characteristics.