JPH07157368A - Production of powdery ceramic stock - Google Patents

Abstract

PURPOSE:To uniformly form a layer of oxide of a metallic element added so as to modify or improve characteristics on the surface of powder of a ceramic basic compsn. CONSTITUTION:Powder of a ceramic basic compsn. insoluble in an org. solvent is mixed with the org. solvent and a metallic salt compd. of org. fatty acid contg. one or more kinds of added metallic elements to prepare a slurry, the compd. is carried and fixed on the powder by drying the slurry and then the powder is calcined or fired.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a ceramic raw material powder,
In particular, the present invention relates to a method for producing a ceramic raw material powder which is useful as a material for ceramic electronic parts.

[0002]

2. Description of the Related Art Generally, when manufacturing a ceramic electronic component, it is possible to add various elements to a basic ceramic composition, for example, a basic composition of a ceramic dielectric, to modify or improve its electrical characteristics. Has been done. As a method of adding this element, a method of coating the surface of each particle of the basic composition powder of the ceramic dielectric with a compound of the additive metal element is adopted. This specific coating method is shown below.

(1) A method of adding a carbonate or oxide of an element to be added to the powder of the basic composition of the ceramic dielectric, or a mixture thereof, mixing and pulverizing, and then calcining.

(2) An aqueous solution containing the ions of the element to be added is added to the slurry of the basic composition powder of the ceramic dielectric, and a precipitant is added to this to form a precipitate of the ions of the element to be added. Then, this is filtered, dried, and calcined.

(3) A method in which a solution of an organic binder and a compound of an element to be added is added to the powder of the basic composition of the ceramic dielectric to make a slurry, which is spray-dried to be granulated and then calcined.

[0006]

[Problems to be Solved by the Invention] However, (1)
In the dry method of (1), it is impossible to uniformly disperse a plurality of carbonates or oxides of additional metal elements in the ceramic basic composition powder. Therefore, the compound of the additive metal element segregates in the ceramic basic composition powder, and the effect of element addition differs between individual particles of the ceramic basic composition powder, making it difficult to obtain the desired characteristics. Therefore, there is a problem in that the characteristics of the ceramic electronic component vary widely.

On the other hand, the wet method (2) improves the dispersibility of the added metal element as compared with the dry method, but it cannot be said to be sufficient.
Moreover, it may be difficult to coprecipitate the ions of a plurality of added metal elements with one type of precipitant. For example, S
Although r, Ca, Mg, etc. can be reacted with carbonate ion (CO ₃ ^-2 ) to precipitate as a complex carbonate,
It is impossible to precipitate Ti ^{4+ and the} like as carbonate with carbonate ion. Further, when an ammonium salt is used as a precipitant, elements such as Zn, Mn, Ni, and Co form an ammine complex and become soluble, so that there is a problem that a precipitate cannot be generated.

Further, the method (3) is a method of adhering the ions of the additive metal element to the surface of the particles when granulating the ceramic basic composition powder. Depending on the type of ions, there is a problem in that the slurry gels due to the interaction with the organic binder, and it becomes impossible to uniformly disperse and adhere the additive metal element.

Therefore, an object of the present invention is to uniformly form an oxide layer of a metal element added for the purpose of modifying or improving the characteristics on the surface of each powder of the ceramic basic composition.

[0010]

In order to achieve the above object, the method for producing a ceramic raw material powder according to the present invention is a method for producing a ceramic basic composition powder which is insoluble in an organic solvent by using an organic solvent and at least one or more kinds. It is mixed with an organic fatty acid metal salt compound containing an added metal element to form a slurry, and the slurry is dried to support and fix the organic fatty acid metal salt compound containing the added metal element on the surface of the ceramic basic composition powder. After that, the ceramic base composition powder is calcined or fired.

The organic fatty acid metal salt compound is soluble in an organic solvent and has the general formula (C _n H _{2n + 1} COO) _m M
is selected from the group of saturated fatty acid metal salt compounds in which n is 5 to 20 or fatty acid metal salt compounds having a cyclo structure (wherein Me represents the added metal element, m represents the valence of the added metal element). It is characterized by comprising at least one kind. Specific examples of the organic fatty acid metal salt compound include a caprylic acid metal salt compound, a capric acid metal salt compound, a myristic acid metal salt compound, a palmitic acid metal salt compound, a stearic acid metal salt compound, and a naphthenic acid metal salt compound. However, it is not limited thereto.

The calcination temperature is the temperature at which the organic fatty acid metal salt compound containing the added metal element is oxidized to form an oxide, and the added metal element reacts in the surface layer of the ceramic basic composition powder to form a solid solution. And is at a temperature to form a core-shell structure.

Further, as the organic fatty acid metal salt compound, a compound that reacts with the surface portion of the ceramic basic composition powder by firing to form a two-layer structure having a core-shell structure, and a ceramic basic composition powder by calcination or firing A compound that reacts with to form a uniform solid solution or a compound that forms a glass component that serves as a sintering aid of the ceramic raw material by calcination or firing is preferable.

The organic solvent has a boiling point of 120.
Those having a temperature of not higher than ° C are suitable, and as the constituent solvent, an organic solvent having a hydrophilic functional group such as an alcohol represented by the general formula C _n H _{2n + 1} OH (provided that n = 2 to 6) can be contained. . That is, as the organic solvent, either a lipophilic organic solvent alone or a mixed system containing a hydrophilic organic solvent can be used. Specific examples of the lipophilic organic solvent include aromatic compounds such as benzene, toluene and xylene, and ketones such as methyl ethyl ketone, and examples of the hydrophilic organic solvent include ethanol, isopropanol and a mixture thereof. However, the present invention is not limited to these.

[0015]

The organic fatty acid metal salt compound is a compound composed of a fatty acid group and a metal ion, and acts as an anionic surfactant in a solvent. On the other hand, when the ceramic basic composition powder and the organic fatty acid metal salt compound are mixed and dispersed in an organic solvent, water is generally present in the form of a monolayer on the surface of the ceramic basic composition powder. Therefore, when mixed and dispersed, a micellar structure in which a fatty acid group site of the organic fatty acid metal salt compound is coordinated is formed on the hydrophilic surface of the ceramic basic composition powder, and the dispersion of the ceramic basic composition powder is improved. To do. The outer side of the micelle coordination structure is lipophilic, and the organic fatty acid metal salt compound is preferentially coordinate-adsorbed to the lipophilic base site. Therefore, the ceramic basic composition powder is dispersed in a form in which the organic fatty acid metal salt compound containing an additive metal element is coated on the surface of each powder, and the ceramic basic composition powder can be added without adding a new surfactant. It becomes possible to uniformly disperse the composition powder in the slurry.

When this slurry is dried by a method such as spray drying, a dry powder is obtained in which the particle surface of the ceramic basic composition powder is uniformly supported and fixed by the organic fatty acid metal salt compound containing the added metal element. Become. Next, when the dry powder is calcined or fired, the compound containing the added metal element becomes a metal oxide, and the ceramic raw material powder in a form in which the particle surface of the ceramic basic composition powder is covered with the metal oxide. Become a body.

[0017]

EXAMPLES Examples of the method for producing ceramic raw material powder of the present invention will be described below. (Example 1) 100 g of barium titanate powder, 100
g of toluene, 500 g of partially stabilized zirconia (PSZ) boulder having a diameter of 5 mm, 0.0193 mol of cerium naphthenate, and 0.0193 mol of titanium nonadecanoate were put in a polyethylene pot and pulverized and dispersed for 16 hours. A slurry was obtained. The obtained slurry was dried by a spray drying method to obtain a dry powder. Then, this dry powder is calcined at 1000 ° C. to obtain 4.5 mol% of Ce.
The added barium titanate powder was obtained.

Next, the distribution state of Ce on the powder surface was subjected to mapping analysis by an X-ray microanalyzer (XMA). As a result, no segregation of Ce was observed, and the powder was uniformly dispersed on the powder surface. Was confirmed.

(Example 2) 100 g of barium titanate powder, 100 g of toluene, 500 g of partially stabilized zirconia (PSZ) boulder having a diameter of 5 mm, cobalt oxide of 0.05 g of cobalt naphthenate, and of niobium oxide. 2.00 g of niobium octylate and 0.60 g of neodymium octylate in terms of neodymium oxide were placed in a polyethylene pot and pulverized and dispersed for 16 hours to obtain a slurry. The obtained slurry was dried by a spray dry method to obtain a dry powder. Then, this dry powder was calcined at 1000 ° C. It was confirmed that this calcined powder had a core-shell structure in which barium titanate particles were used as nuclei, and the periphery thereof was surrounded by layered oxides of Nb, Nd and Co.

(Example 3) 100 g of barium titanate powder, 100 g of xylene, 500 g of partially stabilized zirconia (PSZ) cobblestone having a diameter of 5 mm, and converted to lead oxide of 9.
575 g lead octylate, 1.710 in terms of titanium oxide
g of titanium nonadecanoate and 2.637 g of zirconium octylate in terms of zirconium oxide were put into a polyethylene pot and pulverized and dispersed for 16 hours to obtain a slurry. The obtained slurry was dried by a spray dry method to obtain a dry powder. Then, dry this powder to 700
It was calcined at ℃. It was confirmed that this calcined powder had a core-shell structure in which barium titanate was used as the nucleus and the lead zirconate titanate layer surrounded the barium titanate.

Next, with respect to the dry powder and the calcined powder, the distribution state of Pb, Ti and Zr on the particle surface was subjected to mapping analysis by an X-ray microanalyzer (XMA). Segregation of these elements was not observed in both the fired powder and it was confirmed that they were uniformly dispersed on the powder surface. In addition, when the X-ray diffraction (XRD) analysis was performed on the calcined powder, it was confirmed that the product was lead zirconate titanate.

[0022]

As is apparent from the above description, according to the method for producing a ceramic raw material powder of the present invention, an organic fatty acid metal salt compound containing an additive metal element on each powder surface of the ceramic basic composition Can be uniformly coated, so by calcining or baking it,
An oxide layer of an additive metal element can be uniformly formed on the surface of the ceramic basic composition powder.

By appropriately selecting the metal constituting the oxide, it is possible to easily form a uniform core-shell structure in each powder of the ceramic basic composition.

Claims (9)

[Claims] 1. A ceramic base composition powder insoluble in an organic solvent is mixed with an organic solvent and an organic fatty acid metal salt compound containing at least one or more kinds of additional metal elements to form a slurry, and the slurry is dried. After the organic fatty acid metal salt compound containing the additional metal element is supported and fixed on the surface of the ceramic basic composition powder, the ceramic basic composition powder is calcined or fired. Powder manufacturing method. 2. The organic fatty acid metal salt compound is soluble in an organic solvent and is represented by the general formula (C _n H _{2n + 1} COO) _m Me (where Me is an additive metal element and m is an additive metal element). 2. The ceramic according to claim 1, wherein n is 5 to 20 and at least one selected from the group consisting of saturated fatty acid metal salt compounds or fatty acid metal salt compounds having a cyclo structure. Method of manufacturing raw material powder. 3. The calcination temperature is a temperature at which an organic fatty acid metal salt compound containing an added metal element is oxidized to form an oxide, and the added metal element reacts in the surface layer of the ceramic base composition powder to form a solid solution. The method for producing a ceramic raw material powder according to claim 1, wherein the temperature is between the temperatures at which the core-shell structure is formed. 4. The organic fatty acid metal salt compound comprises a compound which reacts with the surface portion of the ceramic basic composition powder by firing to form a two-layer structure of a core-shell structure. 4. The method for producing a ceramic raw material powder according to any one of 3 above. 5. The organic fatty acid metal salt compound comprises a compound which reacts with the ceramic base composition powder upon calcination or firing to form a uniform solid solution. A method for producing a ceramic raw material powder according to claim 1. 6. The organic fatty acid metal salt compound comprises a compound that constitutes a glass component that serves as a sintering aid of the ceramic raw material by calcination or firing.
4. The method for producing a ceramic raw material powder as described in 2 or 3. 7. The ceramic raw material according to claim 1, 2 or 3, wherein the organic solvent has a boiling point of 120 ° C. or lower and is composed of at least one kind of organic solvent. Powder manufacturing method. 8. The method for producing a ceramic raw material powder according to claim 1, wherein the organic solvent contains an organic solvent having a hydrophilic functional group as its constituent solvent. 9. The ceramic according to claim 8, wherein the organic solvent having a hydrophilic functional group is an alcohol represented by the general formula C _n H _{2n + 1} OH (where n = 2 to 6). Method of manufacturing raw material powder.