JPH0733292B2 - Method for producing powder for ceramic raw material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a ceramic raw material powder used in electronic ceramics.

(Prior Art) As a method for obtaining a finely divided ceramic raw material powder by a wet synthesis method, the present inventors have proposed, for example, the one described in JP-A-59-128263.

The method for producing the ceramic raw material powder comprises the following steps.

That is, in the first tank, at least as a constituent element
To the aqueous solution of nitrate or chloride containing one of Ba, Sr, Ca and Mg, add carbon dioxide gas or soluble carbonate solution such as sodium carbonate and ammonium carbonate to adjust the pH to 7-10, After precipitation, in the second tank, at least Ti, Zr, S as constituent elements
The first step of adding a soluble hydroxide aqueous solution such as caustic soda or ammonium hydroxide to an aqueous solution of a nitrate or chloride containing one of n and Pb to adjust the pH value to 7 to 10 and precipitating it as a hydroxide And a second step of mixing the slurry containing each precipitate obtained by the first step, washing with water after passing, and drying, and a third step of calcining and crushing the obtained powder. It is a method consisting of.

In addition to these, JP-A-59-195574 and JP-A-59-195575.
Japanese Patent Laid-Open No. 59-195576 and the like propose a method for producing a ceramic raw material powder by a wet synthesis method.

Each of the above methods includes, for example, for Ba, a step of adding a solution containing a precipitant such as sodium carbonate to a solution of Ba chloride to adjust the PH value to 7 to 10 and precipitating as a carbonate. It is a thing.

(Problems to be Solved by the Invention) In the above-mentioned step, when the solution containing the precipitant is brought into contact with the solution containing the constituents of the ceramic material, the total volume of the solution containing the constituents of the ceramic material The ratio to Therefore, when contacted with the solution containing the precipitant, the pH value of the contact part of the solution containing the constituent components of the ceramic material became very high, and the pH value of the part not contacted was the same value. State,
There will be a large difference locally in the pH value. Further, as the solution containing the precipitating agent is added to the solution containing the constituents to be the ceramic material, the pH value in the reaction tank gradually changes. At the reaction stage, each product in time series,
That is, the precursor → intermediate compound → ceramic compound is produced, but it is not preferable because the powder properties of the product produced in the initial stage and the product produced in the latter stage are different. Furthermore, each product has a range of pH values in which the chemical species itself exists stably, and if it goes out of the pH value range, it will be redissolved or a chemical species with a different composition ratio will be generated. Become.

As described above, at the stage of adding the solution containing the precipitant to the solution containing the ceramic constituents, the pH values of the portions in contact with each other are significantly different. This will cause re-generation of the product with the deviation.

(Object of the Invention) The present invention provides a production method in which, when a ceramic raw material powder is produced, the product is not redissolved during the reaction process and a product having a different composition ratio is not regenerated. To aim.

(Structure of the Invention) That is, to summarize the present invention, when introducing a first solution containing at least one or more ceramic constituents and a second solution containing a precipitant into the reaction vessel, The first solution and the second solution are fed into the same reaction tank from different routes so that the pH value is suitable for the precipitation conditions of 1., and the first solution and the second solution are mixed. A method for producing a powder for a ceramic raw material, which comprises subjecting a ceramic precipitate to a catalytic reaction and stirring and mixing at a stage of being fed into the reaction tank.

An example of an apparatus for carrying out the method of the present invention will be described with reference to FIG.

In FIG. 1, 1 and 2 are storage tanks for storing a first solution containing at least one or more ceramic constituents and a solution containing a precipitating agent. , 4 are connected to each other, and the first solution and the second solution are connected from the coupling pipe 7 to the reaction tank 8 by the constant amount pumps 5 and 6.
, And contact is made at this stage. In the state shown in the drawing, the first part is formed in front of the reaction tank 8, that is, in the connecting pipe 7.
The solution of No. 2 and the second solution are brought into contact with each other, but it is clear that the variation in the pH value during the contact reaction does not matter because they are sent by the constant amount pumps 5 and 6. The first solution and the second solution sent to the reaction tank 8 are agitated and mixed by an agitating blade 9 connected to a motor 10. Microscopically, the stirring blade 9 provides a uniform mixing action, and if it is large, it provides convection circulation. The stirring blade 9 stirs and mixes at a flow rate of 17 l to 34 l per minute. The first solution and the second solution, which have been mixed by stirring, are precursors in time series →
While going through the steps of intermediate product → ceramic compound,
By the action of the stirring blade 9, it is sent in the direction of the arrow Y, further sent in the direction of the arrow X, and discharged from the sending pipe 11.
In the pipe 11, a slurry containing the produced precipitate is sent out.

The formed precipitate obtained is collected through a washing process. For such a produced precipitate, for example, as shown in FIG. 2, two kinds of produced precipitate A and produced precipitate B prepared by using the apparatus of FIG. 1 are prepared respectively. By mixing the respective precipitates A and B in a predetermined ratio and calcining them, a composite oxide ceramic can be obtained. Examples of the composite oxide ceramics obtained at this stage include various types such as barium titanate type, strontium titanate type, magnesium titanate type, lead zirconate titanate type. Therefore, it is only necessary to prepare the formed precipitate in conformity with the composite oxide ceramic to be obtained.

(Effect) According to the method of the present invention, the first solution containing at least one or more ceramic constituents and the second solution containing the precipitating agent are placed in a quantitative reaction tank so that the pH value is suitable for the precipitation conditions. Since the formed precipitates are obtained by the process of separately feeding and contacting and stirring and mixing at the same time, the generation reaction is carried out one after another in the contact stage in a constant flow, and the pH value shift occurs. There is no risk of re-dissolution of the product in the course of the reaction, and therefore, there is an effect that a product having a consistent composition ratio can be obtained.

(Examples) Hereinafter, the present invention will be described in detail with reference to Examples.

Example 1. First, a solution A in which 2.000 mol of a soluble barium salt such as barium chloride or barium nitrate was dissolved in 10 l of pure water was prepared.
A solution B was prepared by dissolving 7 mol of a precipitant consisting of ₂ CO ₃ or (NH ₄ ) ₂ CO _{3 in} 10 l of pure water.

Put each solution A and B in each storage tank, and send them separately to the reaction tank while controlling the pH value in the reaction tank to be in the range of 8.5 to 10.5 by using the constant volume pump. At the same time, B and B were contact-reacted, and at the same time, they were mixed by stirring in the reaction tank. At this stage, the solutions A and B reacted to produce a precipitate I containing barium.

On the other hand, 2.000 mol of a soluble titanium salt composed of TiCl ₄ and H ₂ O ₂
Make a solution C by dissolving 500 cc in 5 l of pure water, and use NaOH, NH ₄ OH, KO
A solution D was prepared by dissolving 10 mol of a precipitant such as H in 5 l of pure water.

Put each solution C and D in each storage tank, and send them separately to the reaction tank while controlling the pH value in the reaction tank to be in the range of 8.5 to 10.5 by using the constant volume pump. , D were contact-reacted, and simultaneously stirred and mixed in the reaction tank. At this stage, the solutions C and D reacted to form a precipitate II containing titanium.

Two kinds of precipitate I and precipitate thus obtained
Mixing II, Cl ^- washed until no residual was repeated dehydration. The powder obtained in this step was dried and calcined at 900 ° C. The calcined powder was pulverized to obtain barium titanate (BaTiO ₃ ) ceramic powder.

With respect to the obtained ceramic powder, 10 positions were appropriately selected with a spot diameter of 1 μm by a transmission analytical electron microscope, and the molar ratio at that point was analyzed. Table 1 shows the measurement results of the ratio.

As is clear from Table 1, according to this example, the ceramic raw material powder obtained has almost no difference in molar ratio.

Although barium titanate (BaTiO ₃ ) has been described in the above embodiments, it is possible to contain one or more of Sr, Ca, Mn and the like in addition to Ba. In addition to Ti, Zn, Sn, C
It is also possible to contain one kind or two or more kinds such as e, La, Nb and Mn. Note that Mn may be contained in either or both of the Ba side and the Ti side.

Example 2. First, a solution E prepared by dissolving 2.000 mol of a soluble barium salt such as barium chloride or barium nitrate in 10 l of pure water was prepared.
A solution F was prepared by dissolving 7 mol of a precipitant consisting of ₂ CO ₃ or (NH ₄ ) ₂ CO _{3 in} 10 l of pure water.

Put each solution E and F in each storage tank, and send them separately to the reaction tank while controlling the pH value in the reaction tank to be in the range of 8.5 to 10.5 by using the constant volume pump. , F were reacted with each other at the same time with stirring and mixing in the reactor. At this stage, the solutions E and F reacted to generate a precipitate III containing barium.

On the other hand, the total amount of the salts of TiCl ₄ , ZrOCl ₂ · 8H ₂ O, SnCl ₄ , and Bi (NO ₃ ) ₂ · 5H ₂ O (2.004 mol) and H ₂ O ₂ 500cc were dissolved in 10 l of pure water to prepare a solution G, 10 mol of NH ₄ OH, KOH and other precipitants were added to 5 l of pure water.
A solution H dissolved in

Put each solution G and H in each storage tank and send them separately to the reaction tank while controlling the pH value in the reaction tank to be in the range of 8.5 to 10.5 by using the constant volume pump. , H were brought into contact with each other, and at the same time, they were mixed by stirring in the reaction tank. At this stage, the solutions G and H reacted and a precipitate IV containing Ti, Zr, Sn and Bi was produced.

In addition, 0.016 mol of soluble lead salts such as nitrates and acetates and H
Make a solution I of ₂ O ₂ 5 cc dissolved in pure water 1 and add NaOH, NH ₄ O
Solution J prepared by dissolving 1 mol of H, KOH or other precipitating agent in 1 pure water
Made.

Put each solution I and J in each storage tank, and send them separately to the reaction tank while controlling the pH value in the reaction tank to be in the range of 8.5 to 10.5 by using the constant volume pump. , J were brought into contact with each other, and at the same time, they were stirred and mixed in the reaction tank. At this stage, the solutions I and J reacted to generate a precipitate V containing Pb.

Thus three precipitate III was obtained, IV, and V were mixed, Cl ^- washed until no residual was repeated dehydration. The powder obtained through this step was dried and calcined at 900 ° C. The calcined powder was pulverized to obtain barium titanate (BaTiO ₃ ) ceramic powder containing Zr, Sn, Bi and Pb.

With respect to the obtained ceramic powder, 10 positions were appropriately selected with a spot diameter of 1 μm by a transmission analytical electron microscope, and the molar ratio at that point was analyzed. Table 2 shows the measurement results of the molar ratio.

As is clear from Table 2, according to this example, the powder for ceramic raw material obtained has almost no difference in molar ratio.

In the above examples, the three types of precipitates were mixed and calcined to prepare the ceramic raw material powder.
It is also possible to produce three or more kinds of precipitates, mix these, and calcinate them to obtain a powder for a ceramic raw material.

Example 3 First, a soluble salt composed of TiCl ₄ which is a chloride of titanium
A solution K was prepared by dissolving 2.000 mol and 500 cc of H ₂ O _{2 in} 5 l of pure water, and a solution L was prepared by dissolving 10 mol of a precipitating agent such as NaOH, KOH, NH ₄ OH in 5 l of pure water.

Put each solution K, L in each storage tank and send them separately to the reaction tank while controlling the pH value in the reaction tank to be in the range of 8.5 to 10.5 by using the constant volume pump. , L were brought into contact with each other, and at the same time, they were stirred and mixed in the reaction vessel. At this stage, the solutions K and L caused a precipitation reaction to generate a precipitate VI containing titanium.

On the other hand, a solution M in which 2.000 mol of a soluble barium salt such as barium chloride or barium nitrate is dissolved in 10 l of pure water is prepared.
A solution N was prepared by dissolving 7 mol of a precipitant consisting of ₂ CO ₃ or (NH ₄ ) ₂ CO _{3 in} 10 l of pure water.

Put each solution M, N in each storage tank, and send them separately to the reaction tank while controlling the pH value in the reaction tank to be in the range of 8.5 to 10.5 by using a constant volume pump. The slurry of the precipitate VI containing titanium produced in 1 above is fed into the reaction tank using a constant-volume feed pump. At this time, the solution M and the solution N are brought into contact with each other in the reaction tank and simultaneously stirred and mixed in the reaction tank, while the slurry of the precipitate VI containing titanium is also simultaneously sent into the reaction tank and stirred and mixed. The slurry of the precipitate VI containing titanium is sent to the reaction tank so that the supply is completed at the same time as the completion of the precipitation reaction of the solutions M and N. Precipitate containing barium and titanium at this stage
VII is generated.

The thus precipitate VII obtained Cl ^- washed until free and repeated dehydration. The powder obtained through this step was dried and calcined at 900 ° C. The calcined powder was pulverized to obtain barium titanate (BaTiO ₃ ) ceramic powder.

With respect to the obtained ceramic powder, 10 positions were appropriately selected with a spot diameter of 1 μm by a transmission analytical electron microscope, and the molar ratio at that point was analyzed. Table 3 shows the measurement results of the molar ratio.

As is clear from Table 3, according to this example, the powder for ceramic raw material obtained has almost no difference in molar ratio.

In this example, barium titanate (BaTiO ₃ ) was described, but in addition to Ba, one or more of Sr, Ca, Mn and the like may be contained, and Ti, Zn, Sn, Ce, La, Nb, Mn
Etc. may be contained.

In summary of this example, a first solution containing at least one or more ceramic constituents and a second solution containing a precipitating agent are provided so that the pH value is suitable for the precipitation conditions in the reaction vessel. Inject into the same reaction tank from different routes,
A step of preparing a ceramic precipitate by carrying out catalytic reaction and stirring and mixing in the step of sending the first solution and the second solution to a reaction tank is a first step, and then the first solution is added. A third solution containing at least one ceramic constituent different from the ceramic constituent contained therein and a fourth solution containing a precipitating agent are treated in the same manner as in the first step. The solution containing the precipitate of the ceramics obtained in the first step is fed into the reaction tank at the stage of feeding the solution of No. 4 into the reaction tank to carry out the catalytic reaction and stirring and mixing, and the third solution and the fourth solution are mixed. It comprises a step of feeding so that the supply is completed at the same time as the completion of the precipitation reaction.

Comparative Example First, in the first tank, the pH value was adjusted to 9-9.5 by dropwise addition of ammonium carbonate [(NH _{4) 2} CO _3] in an aqueous solution of BaCl _2, Ba
Precipitated as CO ₃ .

In the second tank, 15 ml of 30% hydrogen peroxide solution, which is a stabilizer, was added dropwise to an aqueous solution of TiCl ₄ , and ammonium hydroxide (NH ₄ OH) was added dropwise to adjust the pH to 9 to 9.5. A precipitate containing Ti was obtained.

The slurry of each precipitate was mixed, filtered, and washed with water.
Mix the raw materials for washing with a ball mill and continue to
It was dried and further calcined at a temperature of 900 ° C. for 1 hour to obtain a calcined powder of barium titanate (BaTiO ₃ ).

1 μm of this calcined powder was observed with a transmission type analytical electron microscope.
10 spots with a spot diameter of m were appropriately selected and the molar ratio at that point was analyzed. Table 4 shows the measurement results of the molar ratio.

From Table 4, according to this comparative example, the deviation of the molar ratio at each analysis point is large, and a ceramic powder close to the theoretical value is not obtained. It can be judged that this is because the pH values at the contact reaction stage are largely different locally.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of an apparatus for carrying out the method of the present invention. FIG. 2 is a process chart up to mixing and calcination using the formed precipitate containing the constituent components of the ceramic obtained by the method of the present invention. 1, 2 are storage tanks, 3 and 4 are pipes, 5 and 6 are metering pumps, 7
Is a connecting pipe, 8 is a reaction tank, 9 is a stirring blade, and 10 is a motor.

Claims (2)

[Claims] 1. When introducing a first solution containing at least one or more kinds of ceramic constituents and a second solution containing a precipitating agent into a reaction tank, a pH value suitable for precipitation conditions in the reaction tank. So that the first solution and the second solution are fed into the same reaction tank from different paths, respectively, and contact is made at the stage when the first solution and the second solution are fed into the reaction tank. A method for producing a powder for a ceramic raw material, which comprises reacting and stirring and mixing to obtain a ceramic precipitate. 2. The method according to claim 1, wherein two or more kinds of ceramic raw material powders obtained according to the step are prepared, and the respective ceramic raw material powders are mixed at a predetermined ratio and then calcined. A method for producing a powder for a ceramic raw material according to the item (1).