JPH013002A - Method for producing mixed metal oxide powder and mixed metal oxide powder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for producing mixed metal oxide powder.

[Conventional technology]

Mixed metal oxide powders can be used for co-hydrolysis of metal alcoholates (
cot+hydrolysis). For this purpose, dilute metal alcoholate alcohol solutions are generally prepared and these alcohol solutions are mixed with an alcohol solution of water. The reaction is generally carried out at ambient temperature under an inert nitrogen atmosphere. At the end of this process, the precipitated mixed metal oxide powder is collected [Petter Ceramics Through Chemistry Materials Research Society Symposia]
Proceedings (Better Ceramics)
Through Chemistry-Materi
als Research 5ociety Symp
osiaProcedinBs) -Vol, 32
1984-Elsevier Science Publishing
ing Co, Inc.) -Bruce Fuegre-
(Bruce Fegley et al., 'Synthesis, Characterization, and Processing of Single Particle Size Ceramic Powders (S
synthesis, characterization
n, and processing of monos
ized ceramic powders)', 1
Pages 87-197; U.S. Pat. No. A-4,543,341]. This known method is designed for the production of metal oxide powders of extremely high chemical purity intended for use in ceramic materials.

[Problem to be solved by the invention]

Generally, the performance of ceramic materials is related to the homogeneity of the mixed metal oxide powder used. For this purpose, this time,
It has been discovered that the morphology of the powder obtained by cohydrolysis of metal alcoholates, in particular its homogeneity, can be influenced by the conditions under which the cohydrolysis is carried out. It is therefore an object of the present invention to provide a method for producing mixed metal oxide powders which are in the form of uniform particles and exhibit high chemical homogeneity.

[Means to solve the problem]

The invention therefore relates to a process for the production of mixed metal oxide powders in which the cohydrolysis of metal alcoholates is carried out in the presence of acidic organic compounds containing more than 6 carbon atoms in the molecule.

Within the scope of the present invention, mixed metal oxide powder is understood to mean a powder containing oxides of at least two different metals. According to the invention, the powder can contain more than two different metal oxides.

In the process of the present invention, metal alcoholates are hydrocarbons such as aromatic groups or saturated or unsaturated, linear or cycloaliphatic groups, which are uncompatible or partially or completely substituted. at least one bonded to the group by an oxygen atom
All compounds containing metals. Metal alcoholates containing aliphatic groups are particularly preferred, for example metal alcoholates containing unsubstituted saturated aliphatic groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl groups.

In the process of the invention, the hydrocarbon groups of the metal alcoholates used can be the same or different.

Cohydrolysis consists in simultaneously decomposing a metal alcoholate with water to produce the corresponding hydrated metal oxide and an alcohol or alcohol mixture. It is immaterial whether the operation is carried out with an excess or shortage of water relative to the amount exactly required to decompose all the alcoholate.

The cohydrolysis is controlled in a manner known per se in such a way that the metal oxide precipitates in powder form without bulk gelation of the reaction mixture resulting from the hydrolysis.

According to the invention, the cohydrolysis is carried out in the presence of acidic organic compounds.

The acidic organic compound refers to an organic acid or a derivative of an 8!1 acid. Particular preference is given to saturated or unsaturated carboxylic acids and their derivatives. It is advisable to choose acids or acid derivatives containing more than 6 carbon atoms in the molecule. Carboxylic acids which have proven particularly advantageous are those containing at least 8 carbon atoms in the molecule, such as octanoic acid, lauric acid, palmitic acid, isopalmitic acid, oleic acid, stearic acid. Carboxylic acids containing more than 10 carbon atoms in the molecule are preferred.

Acidic organic compounds have been observed to influence the morphology of mixed metal oxide powders, particularly by inhibiting particle agglomeration and by imparting a spherical profile to the particles. As a general rule, acidic organic compounds should be used in sufficient quantities so that their effect on the powder form is obvious, but at the same time so that the effect on the quality of the powder does not exceed a dark value, beyond which it can become negative. Should. In practice, the optimum amount of acidic organic compound that it is advisable to use depends, in particular, on the acidic organic compound chosen (principally its carbon chain length),
Depending on a number of parameters, including the metal alcoholate used as well as the operating conditions, the optimum amount must be determined for each particular case as a function of the required quality of the powder form. In general, the molar ratio between the acidic organic compound and the metal alcoholate mixture (molar rel
ationship) is at least 10-3; in the case of carboxylic acids,
The preferred molar ratio is 0.005-3, and 0.015-3.
A molar ratio of 0.35 is suitable.

Cohydrolysis can be carried out in ambient air.

However, in order to avoid the risk of uncontrolled decomposition of the metal alcoholate, according to a special embodiment of the process of the invention:
Preferably, the cohydrolysis is carried out in a moisture-free gas atmosphere. Dry, anhydrous air, nitrogen, argon are examples of atmospheres that can be used in this embodiment of the invention. In principle, temperature and pressure are not important. in general,
In most cases, it can be carried out at ambient temperature and atmospheric pressure.

In carrying out the process of the invention, it is preferred to form a homogeneous mixture of metal alcoholate, water and acidic organic compound as soon as possible before nucleation begins. For this reason, it is advantageous to use the alcoholate and water in the form of an organic solution. If appropriate, the organic solvent of the alcoholate is advantageously anhydrous. Furthermore, the absence of solid particles in the organic solution of alcoholate and water is advantageous.

Is it the same for each alcoholate and water? 8 solvents may be used or different organic solvents may be used. In the case of different organic solvents, it is generally advisable that they are miscible. Furthermore, it is also advisable to choose an organic solvent in which the metal oxide formed is insoluble. Alcohols and their derivatives are generally suitable, especially methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol.

The optimum dilution of the alcoholate and water in the respective organic solvents depends on various factors, in particular the alcoholate used, the amount and quality of the acidic organic compound chosen, the operating temperature, the degree of agitation of the reaction mixture and the concentration of the metal oxide powder. Depending on the desired degree of quality, these factors must be determined for each particular case in routine laboratory work. Generally, it is preferred that the organic solution of each alcoholate or mixture of alcoholates and the organic solution of water contain less than 2 moles of metal alcoholate per 11 and less than 5 moles of water per 11, respectively. Particularly advantageous concentrations are from 0.05 to 1 in the case of metal alcoholate solutions and from 0.1 to 3 in the case of aqueous organic solutions.

In the process of the invention, metal oxides are co-precipitated by co-hydrolysis of metal alcoholates in the presence of acidic organic compounds. Various operating methods can be used for this purpose.

According to a first method of operation, each metal alcoholate (for example in the form of an organic solution), water (preferably in the form dissolved in an organic solvent) and the acidic organic compound are introduced separately, but simultaneously, into the reaction chamber. . In an alternative to this method of operation of the invention,
A homogeneous mixture of metal alcoholates is first prepared, for example by dissolving the alcoholates in a common solvent, and then water and the organic compound are added thereto.

According to a second method of operation, a homogeneous mixture of the metal alcoholates is first created and, after addition of the acidic organic compound to this mixture or to the water, the water and the alcoholate mixture are mixed.

Each of these methods of operation is covered by a British patent application G.
It can be operated as described in B-A-2,168,334.

At the end of the cohydrolysis reaction, a finely divided powder consisting of an amorphous metal oxide mixture and more or less hydrated is collected. The powder essentially has a diameter of 5 pm
(microns) or less, it consists of generally spherical particles, usually 0.05 to 2 μm. The powder is generally combined with moisture and organic residues from the hydrolysis reaction, such as organic solvents and acidic organic compounds.

The powder can optionally be subjected to a drying operation and a heat treatment at a suitable temperature to remove the acidic organic compounds, water and organic solvents it contains. The heat treatment can be adjusted to control porosity or to avoid porosity altogether. The heat treatment can also be adjusted to initiate crystallization of the metal oxide.

The method of the present invention can be applied to, for example, tantalum, niobium, barium,
All titanium oxide powders doped with metal oxides or metal oxide mixtures like oxides of copper, strontium, silicon oxide powders doped with boron oxide and zirconium oxide powders doped with aluminum oxides. It can be applied to the production of powdered oxides of known metals. Particularly suitable for the production of mixed metal oxide powders intended for use in ceramic materials, defined as non-metallic inorganic materials whose use starts with powders that require high-temperature treatments such as melting or sintering treatments. (P, William Lee) - “Ceraa+1cs” - 1961 - Reinhold Publishing Corporation (Reinhol
Kirk Othmer, Encyclopedia of Chemical Technology (Encyclopedia of Chemical Technology)
cyclopedia of Chemical Tec
hnology) - 3rd edition - Vol, 5 197ri
; John Wiley & Sons
ley&5ons), U, S, A, -234
-236 pages: 6 Ceramics, scope (Cerami
cs. ~95%) of zirconium oxide with good results.

The powders obtained using the method of the invention, most particularly the zirconia powders stabilized with at least one other metal oxide, exhibit remarkable chemical homogeneity not only on the whole powder scale but also on the particle scale. Features.

Furthermore, the resulting powder is almost free of agglomerates and has a relatively narrow particle size distribution.

Therefore, in the present invention, the average molar ratio (R1) of each metal oxide to the sum of metal oxides in the powder and the molar ratio (R2) of the metal oxide to the sum of metal oxides in the powder particles are It also relates to mixed metal oxide powders such as R3.

In particular, in the case of each particle of the powder and the case of each metal oxide constituting the particle, the above molar ratio (R2) and the ratio to the sum of the metal oxides at a given point in the particle are provided. The present invention relates to a mixed metal oxide powder in which the molar ratio (R3) of the metal oxides is as follows.

In the mixed metal oxide powder of the present invention, the molar ratios R1, R2, and R3 are H.

and (or) z It is a powder that looks like this.

The mixed metal oxide powder of the present invention generally has a diameter of 0.0
It consists of spherical particles having a size of 5 to 2 μm, preferably 0.2 to 0.7 μm.

Preferred powders of the invention are metal oxides in which the constituent metal oxides are selected from rare earths and metal oxides of groups II, III and IV of the Periodic Table of the Elements. These powders are advantageously applied in the use of ceramic materials. Examples of such powders include at least one other metal belonging to one of the above groups;
For example, zirconium oxide powder doped with an oxide of at least one of titanium, yttrium, calcium, magnesium, barium, neodymium and lanthanum.

Among these powders of the invention at least 50 mol%,
Powders containing preferably 75 to 98 mole % zirconium oxide are most advantageous.

The powder of the invention is the powder obtained using the method of the invention as defined above. The present invention particularly provides the above ratio IRI
It relates to mixed metal oxide powders in which R21:R1 is less than 0.25 and powders in which the above-mentioned ratio IR2R31:Rz is less than 0.20, in particular B1 and/or.

The following examples are provided to illustrate the invention. These embodiments will now be described with respect to the accompanying drawings.

FIG. 1 is a diagram for along-grain microanalysis in a microtome section of the powder of the invention.

Figures 2 to 7 are photographs at a magnification of 20,000x showing the grain structure of the doped zirconia powder of the present invention.

The following examples illustrate the following method of operation according to the invention:
This invention relates to the experimental production of another metal oxide doped zirconia powder.

Zirconium Alcoholate An organic solution of the alcoholate of one metal was introduced separately into a reaction chamber maintained under an atmosphere of anhydrous nitrogen.

After a few minutes of maturation time sufficient to produce a homogeneous solution,
A predetermined amount of carboxylic acid was added to this homogeneous solution and the resulting mixture was subjected to moderate stirring for several minutes.

Then, while continuing to stir the mixture vigorously, a specified amount of the organic solution of water was added in one portion to it. Agitation was adjusted to create a homogeneous reaction mixture before nucleation began. next,
The reaction mixture was aged for 2 hours with moderate stirring. After the aging was completed, the reaction mixture was centrifuged and the mixed metal oxides were collected, washed with absolute alcohol, and then dried with a stream of air at ambient temperature.

In the examples, the following relationship [G, 1lerdan - "Small particle statistics (
small particle 5 statistics
)”-2nd edition-1960-Heterworth (BuLte
The average particle diameter of the powder was calculated as defined by Σn, where n indicates the number of particles with diameter d1 in the above relationship.

Example 1 This example relates to the production of zirconia powder doped with yttrium oxide. This example is characterized by the following operating conditions.

Organic solution of metal alcoholate: 100++ Il of 0.2 M ethanol solution of zirconium n-butoxide.

Organic solution of 3 ml of 0.4 M isopropanol solution of yttrium isopropoxide, 1.6 x 10-" moles of carboxylic nioleic acid, water: 100 Il of 0.7 M ethanolic solution of water
, Implementation temperature = 25°C.

The resulting powder is shown in Figure 2 and has an average particle diameter of 0.87 μm.

Furthermore, the molar ratio Y2O3 moles + moles of ZrO is measured (a) for the entire powder sample, (b) for five randomly taken particles from the powder, and (C) for the diameter of one particle of the powder. along, thickness approx.
．． The tests were carried out on different areas of a 1 μm microtome thin section.

The measurement ta+ was performed using chemical analysis.

Measurements (bl) were carried out by X-ray microanalysis using a Scanning Electron Microscope Series 2000 supplied by Cambridge, fitted with an Emerging Energy Diffraction X-ray Microanalyzer supplied by Tracor. .

Measurements fc) were carried out by X-ray microanalysis with a Siemens model 102i3 microscope equipped with an energy diffraction X-ray microanalyzer supplied by Kevex.

The results of the measurements (al and fb) are shown in the table below.

The results of measurement (C) are reproduced in the diagram of FIG. 1 showing the distribution of radiation intensity for the detection of yttrium. The horizontal axis of the diagram illustrates the scan line of the analyzer;
The vertical axis indicates the molar concentration of yttrium oxide (molar ratio Ra defined above).

Examining the above table and diagram, we reach the following conclusions:

In the case of a sample of 5 particles, tl.

along the diameter of the particle This example differs from the example in the following operating conditions.

Organic solution of metal alcoholate: 100 ml of 0.2 M propazine solution of zirconium n-propoxide, 3 liters of 0.4 M isopropanol solution of yttrium isopropoxide, 4.8 x 10-3 mol of carboxylic acid nioleic acid in water. Organic solution: 100mf of 1.25 Li propatool solution in water
, and implementation temperature: 25°C.

The obtained powder is shown in FIG. The powder has an average particle diameter of 0.32 μm.

Example 3 In this example, a titanium dioxide doped zirconia powder was prepared. The preparation was carried out under the following operating conditions.

Organic solution of metal alcoholate: 100 mN of 0.2M propatool solution of zirconium n-propoxide, 4 mN of 0.5M propatool solution of titanium n-propoxide! , carboxylic acid nioleic acid 3.2 X L O-' molar organic solution in water: 0.7 M n-propertool solution in water 1
00m1. , and operating temperature: 25° C. FIG. 4 shows a sample of the powder obtained. The powder consists of spherical particles of zirconia and titanium dioxide, the average diameter of which is 0.88 μm.

Example 4 In this example, zirconia and calcium oxide powders were prepared. For this purpose, the following operating conditions were used.

Organic solutions of metal alcoholates: 30 mf of a 0.2 M n-propertool solution of zirconium n-propoxide, zirconium n-butoxide and n-propoxide (0
, 46M) and calcium ethoxide (0,08M) in a mixture of n-propatool and impropatool 30-, carboxylic acid nioleic acid 4.8X10-3 mol water and organic solution: water 0.7 M n-propertool solution 1.0O
mjl! , and operating temperature = 70°C.

In carrying out this example, two metal alcoholate solutions were first mixed, then the resulting mixture was diluted with 20 bottles of impropat tool, and then heoleic acid was introduced therein. In this case, the subsequent operations were as described above in Examples 1-3.

A sample of the obtained powder is shown in FIG. This powder is in the form of spherical particles with an average diameter of 1.2 μm.

Example 5 In this example, zirconium oxide and magnesium oxide powders were produced. The procedure was the same as in Example 1, and the following reactants were used.

Organic solution of metal alcoholate: 50 ml of 0.2 μm-propanol solution of zirconium n-propoxide, 15 ml of n-propanol solution of zirconium n-propoxide (0.67M) and magnesium ethoxide (0.12M) carboxylic acid; Organic solution of oleic acid 3.2 x 10-3 molar water: 0.7 M n-propanol solution in water 100-
1 and implementation temperature: 50°C.

A sample of the powder obtained is reproduced in FIG.

This powder consists of spherical particles with an average diameter of 0.68 μm.

Example 6 This example relates to the production of zirconia powder doped with neodymium oxide.

The procedure was as described above in Example 1, using the following reactants.

Organic solutions of metal alcoholates: 50 ml of a 0.2 M n-propanol solution of zirconium n-propoxide, 40 ml of a 0.06-1 isopropanol solution of neodymium isopropoxide, 2.4 X 10-3 mol of carboxylic acid nioleic acid , organic solution of water: 1.25 μm-propertool solution of water 50 ml
1 liter, and operating temperature: 50°C.

Figure 7 shows a sample of the powder obtained. This powder consists of spherical particles of zirconium oxide and neodymium oxide with an average diameter of 0.3 μm.

[Brief explanation of drawings]

FIG. 1 is a diagram for along-grain microanalysis in a microtome section of the powder of the invention. Figures 2-7 are photographs at 20.000X magnification showing the grain structure of the doped zirconia powder of the present invention. Fig.2 Fig.3 Fig.4 Person Name (5995) Patent Attorney Minoru Nakamura U)
1 amount (same volume: 1 Komata history 7 pieces

Claims (1)

[Claims] (1) A mixture comprising co-hydrolyzing a metal alcoholate, characterized in that the co-hydrolyzing is carried out in the presence of an acidic organic compound containing more than 6 carbon atoms in the molecule. Method for producing metal oxide powder. 2. A method according to claim 1, characterized in that (2) the acidic organic compound is selected from carboxylic acids. (3) Add the acidic organic compound to 0 molar amount of the metal alcoholate.
．． Claim 1, characterized in that it is used in an amount of 005 to 3 times.
Or the method described in 2. (4) In order to carry out the cohydrolysis, the metal alcoholate, water and acidic organic compound are mixed to form a homogeneous mixture before nucleation begins.
The method according to any one of the above. (5) 0.0% alcoholate per liter of metal alcoholate.
used in the form of an alcoholic solution containing 0.5 to 1 mol;
5. Process according to claim 1, characterized in that the water and water are used in the form of an alcoholic solution of water containing 0.1 to 3 mol of water per liter. (6) Any one of claims 1 to 5, wherein the metal alcoholate is selected from alcoholates of rare earth metals and alcoholates of metals from groups II, III and IV of the periodic table of elements.
The method described in section. (7) The average molar ratio of each metal oxide to the sum of metal oxides in the powder (R_1) and the average molar ratio of the metal oxide to the sum of metal oxides in one particle of the powder (R_2) A mixed metal oxide powder in which |R_1-R_2|/R_1≦0.30. (8) For each particle of the powder and for each metal oxide constituting each particle, the molar ratio R_2 listed above and the molar ratio of the metal oxide to the sum of the metal oxide at any point in the particle. The ratio (R_3) is |R_2-R_3|/R_2
Powder according to claim 7, characterized in that ≦0.30. (9) The molar ratios R_1, R_2 and R_3 are as follows: 0.03≦|R_1-R_2|/R_1≦0.20 and/or 0.08≦|R_2-R_3|/R_2≦0.18 The powder according to claim 7 or 8, characterized by: (10) The powder according to any one of claims 7 to 9, characterized in that the powder consists of spherical particles having a diameter of 0.05 to 2 μm. (11) Metal oxides include rare earth metals and I of the periodic table of elements.
Powder according to any one of claims 7 to 10, characterized in that it is an oxide of a metal selected from metals of groups I, III and IV. (12) The powder according to claim 11, characterized in that the powder contains 75 to 98 mol % of zirconium oxide. (13) Any one of claims 7 to 12, which can be obtained by the method described in any one of claims 1 to 6.
Powder as described in Section.