JP2010222189A - Method for manufacturing ceramic powder having improved dispersibility and method for producing dispersion of ceramic powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide ceramic powder having excellent dispersibility which can be made dense, and a dispersion thereof. <P>SOLUTION: The ceramic powder having improved dispersibility is manufactured by charging raw material ceramic powder into a liquid medium (for example, dispersion medium) to produce radical species in the medium while fluidizing the medium into which the raw material ceramic powder is charged. The radical species is produced by generating plasma (submerged plasma) in the medium. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a ceramic powder with improved dispersibility and a method for producing a dispersion of ceramic powder.

  In many cases, a ceramic molded body is manufactured by the following steps: Dispersing ceramic powder in a predetermined medium, molding the obtained dispersion into an appropriate shape, and firing the molded body.

  By the way, in order to form this type of ceramic molded body uniformly and at a high density, it is necessary to improve the dispersibility of the ceramic powder in the dispersion (that is, to make the dispersion state uniform). In order to improve dispersibility, a dispersant is generally added to the medium.

  In order to further improve the dispersibility, an attempt may be made to increase the amount of the dispersant adsorbed on the surface of the ceramic particles. At this time, generally, for example, a relatively large amount of a low molecular weight dispersant is added, or a so-called high molecular dispersant is added. However, in this method, there is a concern that a relatively large amount of surplus dispersant (that is, a free dispersant not adsorbed on the surface of the ceramic particles) is generated in a relatively large amount, thereby reducing the density of the molded body.

上記式において、Ｍは材料粒子表面の分散剤の吸着サイト、Ｄは分散剤、Ｍ−Ｄは吸着サイトに分散剤が吸着したもの、Ｋは平衡定数を示す。上記式の通り、吸着サイトに分散剤が吸着したものＭ−Ｄと、吸着していないフリーの分散剤Ｄとは、平衡関係にある。吸着量を多くするためには分散剤を多く添加する必要がある一方、分散剤を多く添加すると、上述の平衡関係のため、同時にフリーの分散剤が増加してしまう。

In the above formula, M is the adsorption site of the dispersing agent on the surface of the material particles, D is the dispersing agent, M-D is the adsorption site of the dispersing agent, and K is the equilibrium constant. As shown in the above formula, the sample MD with the dispersant adsorbed on the adsorption site and the free dispersant D not adsorbed are in an equilibrium relationship. In order to increase the amount of adsorption, it is necessary to add a large amount of dispersant, but when a large amount of dispersant is added, the amount of free dispersant increases at the same time due to the above-described equilibrium relationship.

  The present invention has been made to address the above-described problems. That is, an object of the present invention is to provide a ceramic powder and a dispersion thereof having good dispersibility and capable of increasing the density of a molded body.

  In the above formula, the present inventor increases the adsorption site M on the left side to increase the right side MD and decreases the free dispersant D on the left side. Focusing on the fact that the density can be increased, the present invention has been achieved.

  A feature of the present invention is that raw material ceramic powder is put into a liquid medium (for example, dispersion medium) capable of generating radical species, and the medium in which the raw material ceramic powder is put is flowed in the medium. By generating the radical species, a ceramic powder with improved dispersibility and a dispersion thereof are produced.

  The radical species can be generated by applying a voltage (alternating current or pulsed) between a pair of electrodes immersed in the medium to generate plasma (liquid plasma) in the medium. When an aqueous solution is used as the medium, the radical species is typically OH · or H ·.

  When producing a ceramic powder with improved dispersibility, a drying step is finally performed (a washing step or the like is usually performed prior to the drying step, but this is not essential). In the drying step, any drying process such as hot air drying, spray drying, freeze drying, or the like can be used. Such a drying step is preferably performed at a low temperature (for example, 150 ° C. or lower).

  In the method of the present invention, the surface is modified by the reaction between the radical species generated in the medium and the surface of each particle of the raw ceramic powder. Specifically, a specific functional group (for example, a hydroxyl group) is imparted to the surface by this reaction. Thereby, the dispersibility of the ceramic powder is improved.

  That is, for example, the amount of the specific functional group for adsorbing the dispersant in the ceramic powder after the reaction with the radical species is increased as compared with the raw ceramic powder before the reaction. Then, when the raw ceramic powder is put into the dispersion medium and dispersed without performing the reaction with the radical species, the dispersant, which should be surplus, is increased by the reaction with the radical species. It can be adsorbed to the group. As a result, the amount of the dispersant adsorbed effectively increases, and the excess amount of the dispersant effectively decreases.

  Therefore, according to the present invention, it is possible to provide a ceramic powder and a dispersion thereof having good dispersibility and capable of increasing the density of a molded body.

  In the method of the present invention, the reaction between the surface of each particle of the raw material ceramic powder and the radical species is performed while flowing (stirring) the liquid medium in which the powder is charged. Therefore, unlike the dry process using an air plasma process or the like, the surface modification can be performed uniformly over almost the entire surface of the particles. Moreover, the occurrence of reaggregation of particles can be satisfactorily suppressed. Furthermore, continuous processing by a distribution system is possible.

  When the radical species are generated by submerged plasma, a shock wave acts in the vicinity of the plasma. Therefore, the modification can be performed while the weak aggregates are crushed by the shock wave.

  In the method of the present invention, the surface of each particle of the raw ceramic powder reacts with the radical species in the liquid to modify the surface. Therefore, unlike other methods using mechanochemical treatment or the like, the surface modification can be performed without inadvertently changing the crystal state or the particle size distribution.

  The method of the present invention can be suitably used when improving the dispersibility by introducing a hydroxyl group into the particle surface of the oxide ceramic powder. In particular, even when the particle diameter is small, it is possible to effectively suppress the occurrence of aggregation by increasing the amount of hydroxyl group on the particle surface and increasing the amount of adsorption of the dispersant.

  Furthermore, as described above, by performing the drying step at a low temperature, the elimination of functional groups (OH groups and the like) introduced to the particle surface by the reaction with the radical species can be satisfactorily suppressed.

It is the schematic which shows the principal part structure of an example of the apparatus for enforcing the manufacturing method of this invention. It is a FT-IR spectrum of an example and a comparative example. It is the schematic which shows the principal part structure of the other example of the apparatus for enforcing the manufacturing method of this invention. It is the schematic which shows the principal part structure of another example of the apparatus for enforcing the manufacturing method of this invention.

  Embodiments and representative examples of the present invention will be described below with reference to the drawings as appropriate. In addition, the description about the following embodiment is specific to the extent possible, merely an example of the embodiment of the present invention in order to satisfy the description requirement (description requirement / practicability requirement) of the specification required by law. It is only what is described in.

  Therefore, as will be described later, it is quite natural that the present invention is not limited to the specific configurations of the embodiments described below. Various modifications that can be made to the present embodiment are listed together at the end, as they would interfere with the understanding of the consistent description of the embodiment if inserted during the description of the embodiment. .

<Outline of apparatus configuration for carrying out manufacturing method of embodiment>
FIG. 1 is a schematic diagram showing the main configuration of an example of an apparatus for carrying out the manufacturing method of the present invention. The manufacturing apparatus 1 includes a storage tank 2, a stirrer 3, and an in-liquid plasma generator 4.

  A medium S that is an aqueous solution with adjusted conductivity is stored in the storage tank 2. The stirrer 3 causes the medium S to flow (stir) in the storage tank 2.

  The in-liquid plasma generator 4 includes a pair of electrodes 4a. The pair of electrodes 4 a is provided in the storage tank 2 so as to be immersed in the medium S stored in the storage tank 2. In addition, the pair of electrodes 4a is arranged so as to generate radical species by applying a voltage between the pair of electrodes 4a to generate plasma (in-liquid plasma) in the medium S.

  Specifically, the electrode 4a is fixed to the electrode holder 4b so that the tip is exposed. The pair of electrode holders 4b are supported by support means (not shown) so that the pair of electrodes 4a face each other with a predetermined gap therebetween. The pair of electrodes 4a is electrically connected to the power source 4c.

<Outline of Manufacturing Method of Embodiment>
The manufacturing method of this embodiment includes the following steps.
(1) Raw material ceramic powder is put into the medium S, which is an aqueous solution capable of generating OH · or H · as radical species.
(2) While the medium S in which the raw ceramic powder is charged is flowed (stirred) by the stirrer 3, a voltage is applied between the pair of electrodes 4 a to generate plasma (liquid plasma) in the medium S. Thus, OH · or H · is generated in the medium S.

  The OH · or H · generated in the medium S reacts with the surface of each particle of the raw ceramic powder to modify the surface. Specifically, this reaction gives a hydroxyl group to the surface.

  Therefore, for example, after the step (2), the ceramic powder is washed, filtered, and dried to obtain a powder having improved dispersibility, which is made of ceramic particles having a large amount of hydroxyl groups introduced to the surface. Such a powder can be well dispersed in water (in an aqueous solution) without using a dispersant depending on the particle size (for example, submicron level) and the amount of hydroxyl group introduced.

  Alternatively, by using a dispersion medium as the medium S and adding the dispersant after the step (2), the amount of the dispersant adsorbed on the ceramic particles is increased as compared with the conventional case. For this reason, the dispersion liquid of a favorable dispersion state can be obtained with a smaller amount of dispersant than before. Moreover, generation | occurrence | production of the excess dispersing agent in a dispersion liquid can be suppressed effectively. Therefore, a higher density ceramic molded body can be obtained by appropriately adjusting the viscosity and the like of this dispersion to form a slurry, which is molded and sintered.

  Hereinafter, specific process contents and evaluation results of an example of the manufacturing method of the present invention will be described in contrast to a comparative example.

<Example>
(A) By adding KCl to ion-exchanged water, a medium that is a KCl aqueous solution with conductivity adjusted to 1 mS / cm was prepared.
(B) To 100 ml of medium, 5 g of PZT (Pb (Zr _0.52 Ti _0.48 ) O ₃ ) powder is added, and dispersion treatment is performed for 2 minutes with a 300 W ultrasonic homogenizer (manufactured by Nippon Seiki Seisakusyo Co., Ltd .: product number US-300T). went.
(C) The above dispersion was put into a 200 ml beaker as the storage tank 2.
(D) In-liquid plasma was generated while stirring with a magnetic stirrer (5 minutes).
(E) After repeating the suction filtration and washing several times, the surface-modified ceramic powder was obtained by drying at 100 ° C.

  The submerged plasma generation conditions in the above step (D) are as follows: the electrode 4a is a tungsten electrode having a diameter of 1 mm (tip is cylindrical), the gap between the electrodes is 5 mm, and the voltage is a pulsed voltage of 0 V / 2 kV ( 20 kHz, pulse width 1.7 μsec, power output 200 W).

The PZT powder was synthesized as follows: PbO, ZrO ₂ , and TiO ₂ in powder form were weighed so as to have the above composition, and these were then calibrated in a polyethylene pot. Wet mixed using ₂ mm ZrO ₂ beads, dried and heat treated. As a result of observing the synthesized powder with a scanning electron microscope, the particle diameter of the powder was about 100 nm, and the isoelectric point was about pH = 6.0.

<Comparative Example 1>
(B ′) 5 g of PZT powder was added to 100 ml of a medium composed of ion-exchanged water, and a dispersion treatment was performed for 2 minutes with a 300 W ultrasonic homogenizer (same as above).
(E) After repeating the suction filtration and washing several times, the surface-modified ceramic powder was obtained by drying at 100 ° C.

<Comparative example 2>
(B ′) 5 g of PZT powder was added to 100 ml of a medium composed of ion-exchanged water, and a dispersion treatment was performed for 2 minutes with a 300 W ultrasonic homogenizer (same as above).
(C ′) The above dispersion was put into a 500 ml container made of Hastelloy (registered trademark) attached to an autoclave (manufactured by OM Lab Tech Co., Ltd .: product number MMJ-500).
(D ′) The container was set in an autoclave and hydrothermally treated at 150 ° C. for 4 hours while stirring with an attached stirrer.
(E) After repeating the suction filtration and washing several times, the surface-modified ceramic powder was obtained by drying at 100 ° C.

<Comparative Example 3>
(B ′) 5 g of PZT powder was added to 100 ml of a medium composed of ion-exchanged water, and a dispersion treatment was performed for 2 minutes with a 300 W ultrasonic homogenizer (same as above).
(C ′) The above dispersion was charged into an autoclave container (same as above) manufactured by Hastelloy (registered trademark).
(D ″) Hydrothermal treatment at 250 ° C. for 4 hours in an autoclave (same as above).
(E) After repeating the suction filtration and washing several times, the surface-modified ceramic powder was obtained by drying at 100 ° C.

<Evaluation result 1: Thermogravimetric analysis>
Table 1 shows the results obtained by analyzing the powders obtained in the above Examples and Comparative Examples 1 to 3 with a thermogravimetric analyzer (manufactured by Rigaku Corporation: product number TGA50). This analysis was performed under the following conditions: room temperature to 500 ° C. (temperature increase rate: 10 ° C./min) under air flow.

  The amount of weight reduction in Table 1 corresponds to the amount of hydroxyl group eliminated in thermogravimetric analysis. Therefore, as is apparent from the results in Table 1, the amount of hydroxyl group introduced into the ceramic particle surface by the plasma treatment in liquid in the examples (difference between the example and the comparative example 1) has been generally performed conventionally. The amount was much larger than the amount of hydroxyl groups introduced by hydrothermal treatment (difference between Comparative Example 2 or 3 and Comparative Example 1).

<Evaluation result 2: FT-IR analysis>
Samples prepared by diluting and blending the powders obtained in the above-mentioned Examples and Comparative Examples 1 to 3 with KBr powder to form tablets, FT-IR analyzer (manufactured by PerkinElmer Co., Ltd .: product name spectrum2000) FIG. 2 shows the result of analysis by the diffuse reflection method.

As shown in FIG. 2, in the example, the peak at 3280 cm ⁻¹ due to the OH stretching vibration was significantly increased as compared with Comparative Examples 1 to 3. It can be said that this FT-IR spectrum also supports the increase in the amount of hydroxyl groups introduced to the ceramic particle surfaces by the in-liquid plasma treatment in the examples.

<Evaluation result 3: wettability of powder to various solvents>
After adding the powder obtained by the above-mentioned Example and the comparative example 1 so that it might become 0.1 wt% with respect to butanol, ethanol, and water, after performing a dispersion process for 2 minutes with a homogenizer, laser diffraction type | mold Table 2 shows the results (median diameter) of the particle size analysis using a flow distribution measuring apparatus (manufactured by Horiba, Ltd .: product number LA920).

  When the wettability of the powder with respect to the solvent is poor, agglomeration occurs remarkably, and the particle size obtained as a result of the analysis becomes large. In this regard, as shown in Table 2, the powder obtained in Comparative Example 1 had the worst wettability with water and the best wettability with butanol. On the other hand, the powders obtained by the examples had the worst wettability to butanol and the best wettability to water. From this result, it can be said that the powder obtained by the Example was made more hydrophilic than the Comparative Example.

<Evaluation result 4: Dispersibility>
The powder and the dispersant are added to water so that the powder obtained in the above-mentioned Example and Comparative Example 1 is 5 wt%, and the hexanoic acid as the dispersant is 5 wt%, and the dispersion treatment is performed with a homogenizer for 2 minutes. Went. Thereafter, the powder was collected by suction filtration, and washing with butyl acetate and suction filtration were repeated three times for the collected powder.

The powder subjected to the above treatment was subjected to thermogravimetric analysis in the same manner as described above. Moreover, after adding this powder so that it might become 1 wt% with respect to toluene, after performing the dispersion process for 2 minutes with a homogenizer, the particle size analysis was carried out similarly to the above-mentioned. These results are shown in Table 3. The “adsorption amount” in the table is obtained by subtracting a portion corresponding to the desorption amount of a hydroxyl group (see Table 1) from the weight decrease amount in the present thermogravimetric analysis.

  As shown in Table 3, in the powder obtained by the example, compared with Comparative Example 1, the amount of hexanoic acid increased and dispersed in toluene in a state where hexanoic acid was adsorbed. Improved.

  By the way, the approach distance of the powder to the plasma generation part is an important parameter for effectively using radical reaction, thermal energy, and shock wave. Therefore, the relationship between the approach distance and the reaction state was evaluated by changing the stirring conditions.

  When the stirring is performed at 20 rpm, the powder is simply rotated around the bottom of the container 40 mm away from the plasma generation unit. In that state, the processing did not proceed at all, and the same result as in Comparative Example 2 was obtained. The stirring speed was gradually increased, and improvement in dispersibility was observed at about 40 rpm. The distance between the powder and the electrode at that time was close to about 20 mm.

  Further, when the stirring speed was increased to 1000 rpm, the powder was supplied to the vicinity of the plasma, specifically, less than 1 mm by the vortex. In that case, however, the powder turned black. The reason seems to be that the powder was pyrolyzed and carbonized due to excessive supply of thermal energy.

  From the above, the preferable condition is that the approach distance of the powder to the plasma generating portion is 1 mm or more and 20 mm or less. In addition, from this result, in the Example, stirring was implemented at 200 rpm.

<List of examples of modification>
Note that the above-described embodiments and examples are merely examples of typical implementations of the present invention that the applicant has considered to be the best at the time of filing of the present application, as described above. Therefore, the present invention is not limited to the above-described embodiments and examples. Therefore, it goes without saying that various modifications can be made to the above-described embodiments and examples without departing from the essential part of the present invention.

  Hereinafter, some typical modifications will be exemplified. However, it goes without saying that the modifications are not limited to those listed below. In addition, all or some of the plurality of modified examples can be combined with each other as appropriate within a technically consistent range.

  The present invention (especially those expressed functionally and functionally in the constituent elements constituting the means for solving the problems of the present invention) is based on the above-described embodiment and the description of the following modifications. Should not be interpreted as limited. Such a limited interpretation is unacceptable and improper for imitators, while improperly harming the applicant's interests (rushing to file under a prior application principle).

  There is no particular limitation on the type of powder. Further, the particle diameter may be smaller than the size that can be dispersed in the liquid.

  The present invention is not limited to the specific apparatus configuration shown in the above embodiment.

  For example, the material and shape of the electrode 4a, the gap width, the type and conductivity of the medium S, and the like are not particularly limited as long as plasma is generated.

  The medium S is heated by the generation of plasma in the liquid, and the radical addition reaction is promoted by this heat. At this time, it is preferable to control the temperature of the medium S to be substantially constant while suppressing the temperature of the medium S below the boiling point by a method such as cooling the storage tank 2 from the outside. As a result, the thermal energy of the plasma for promoting the addition reaction of radicals can be kept constant (if the thermal energy is low, the reaction does not proceed easily, and if the thermal energy is large, bubbles are generated and the radical cannot be used effectively).

The material for adjusting the conductivity is not particularly limited as long as it dissolves in water. For example, a water-soluble salt (H, K, Na, NH ₄ as a cation, Cl, NO ₃ , SO ₄ as an anion) , OH) or the like. Further, in the case of an ammonium salt, an NH ₂ group may be provided. In particular, the reactivity can be improved by adjusting the pH so that the surface charge of the powder is reduced. This is because the surface charge inhibits the access of radical species. Specifically, the isoelectric point is preferably −3 or more and +3 or less.

  As the applied voltage, an arbitrary voltage such as high frequency or microwave can be used. A waveform having a peak not only on the positive potential side but also on the negative potential side can be used.

  FIG. 3 is a schematic view showing the main configuration of another example of an apparatus for carrying out the manufacturing method of the present invention. As shown in FIG. 3, the manufacturing apparatus 1 may further include a medium circulator 5. The medium circulator 5 includes a medium circulation path 5a, a flow pump 5b, and a wet crushing / pulverizing machine 5c.

  An inlet 5 a 1 in the medium circulation path 5 a is provided so as to open at the bottom of the storage tank 2. Further, the outlet 5 a 2 in the medium circulation path 5 a is provided so as to open at the upper part of the storage tank 2. That is, the medium circulation path 5 a is provided so as to lead out the medium S from the bottom of the storage tank 2 and return the derived medium S to the upper part of the storage tank 2.

  The flow pump 5b is interposed in the medium circulation path 5a so as to send the medium S from the inlet 5a1 to the outlet 5a2 in the medium circulation path 5a. The wet crushing / pulverizing machine 5c is interposed in the medium circulation path 5a and crushes / crushes the ceramic powder aggregate in the medium S.

  In the manufacturing apparatus 1 having such a configuration, the medium S flows in the storage tank 2 by the operation of the flow pump 5b (therefore, the stirrer 3 can be omitted in the configuration shown in FIG. 3). At this time, the ceramic powder aggregate in the medium S is pulverized / pulverized by the wet pulverization / pulverization machine 5c.

  According to the flow-type apparatus configuration of this modification, crushing / pulverization and reforming can be performed simultaneously and continuously.

  FIG. 4 is a schematic view showing the main configuration of still another example of an apparatus for carrying out the manufacturing method of the present invention. As shown in FIG. 4, the in-liquid plasma generator 4 may be interposed in the medium circulation path 5a. That is, in this modification, the in-liquid plasma generation tank 4d is interposed in the medium circulation path 5a. A pair of electrode holders 4b holding the electrodes 4a are attached to the submerged plasma generation tank 4d.

  Also in the configuration of this modified example, as in the above modified example (see FIG. 3), crushing / pulverization and modification can be simultaneously and continuously processed. Furthermore, according to the configuration of the present modification, it is possible to uniformly and satisfactorily perform the reforming process on most particles in the medium S passing through the medium circulation path 5a by the operation of the medium circulator 5. .

  The raw material ceramic powder used in the present invention may be in the form of powder or slurry when it is put into the medium. In the latter case, since the ceramic powder is dispersed and put into the medium, the modification is performed more uniformly. As a dispersion method in this case, a general wet method such as wet pulverization using beads, a homogenizer using a jet mill or ultrasonic waves, or the like can be used. The dispersion medium for obtaining this slurry may be the same as or different from the medium at the time of modification, and a material having good compatibility with the powder to be used can be used as appropriate.

  The modified dispersion may be used as it is, or may be pulverized by drying, or may be made into a paste by concentration or the like.

  Other modifications not specifically mentioned are naturally included in the scope of the present invention as long as they do not change the essential part of the present invention. In addition, in each element constituting the means for solving the problems of the present invention, the elements expressed in terms of operation and function are the specific structures disclosed in the above-described embodiments and modifications, It includes any structure that can realize this action / function. Furthermore, the disclosure content (including the specification and drawings) of the prior applications and publications cited in this specification may be incorporated as a part of this specification.

DESCRIPTION OF SYMBOLS 1 ... Manufacturing apparatus 2 ... Reservoir 3 ... Stirrer 4 ... Submerged plasma generator 4a ... Electrode 4b ... Electrode holder 4c ... Power supply 4d ... Submerged plasma generator 5 ... Medium circulation machine 5a ... Medium circulation path 5a1 ... Inlet 5a2 ... Outlet 5b ... Fluid pump 5c ... Wet crusher S ... Medium

JP 2001-30227 A JP 2001-106578 A JP 2001-130968 A JP 2008-13810 A Japanese Patent No. 3925932

Claims (11)

A method for producing a ceramic powder with improved dispersibility, comprising:
Raw material ceramic powder is put into a liquid medium that can generate radical species,
Producing the radical species in the medium while flowing the medium in which the raw ceramic powder is charged;
A method for producing a ceramic powder with improved dispersibility, characterized by drying. A method for producing a ceramic powder with improved dispersibility according to claim 1,
The raw ceramic powder is preliminarily made into a slurry and then charged into the medium.
A method for producing ceramic powder with improved dispersibility. A method for producing a ceramic powder having improved dispersibility according to claim 1 or 2,
A voltage is applied between a pair of electrodes immersed in the medium to generate plasma in the medium, thereby generating the radical species,
The raw material ceramic powder is supplied from the plasma generation part to 1 mm or more and within 20 mm,
A method for producing ceramic powder with improved dispersibility. A method for producing a ceramic powder with improved dispersibility according to any one of claims 1 to 3,
The method for producing a ceramic powder with improved dispersibility, wherein the medium is an aqueous solution. A method for producing a ceramic powder with improved dispersibility according to claim 4,
The method for producing a ceramic powder having improved dispersibility, wherein the radical species is OH · and / or H ·. A method for producing a dispersion of ceramic powder,
Raw material ceramic powder is put into a liquid dispersion medium that can generate radical species,
A method for producing a dispersion of ceramic powder, wherein the radical species is generated in the dispersion medium while flowing the dispersion medium in which the raw ceramic powder is charged. A method for producing a dispersion of ceramic powder according to claim 6,
The raw ceramic powder is previously slurryed and then charged into the dispersion medium,
A method for producing a dispersion of ceramic powder. A method for producing a dispersion of ceramic powder according to claim 6 or 7,
By generating a plasma in the dispersion medium by applying a voltage between a pair of electrodes immersed in the dispersion medium, to generate the radical species,
A method for producing a dispersion of ceramic powder, characterized in that the raw material ceramic powder is supplied within a range of 1 mm to 20 mm from a plasma generating portion. A method for producing a dispersion of ceramic powder according to any one of claims 6 to 8,
The method for producing a dispersion of ceramic powder, wherein the dispersion medium is an aqueous solution. A method for producing a dispersion of ceramic powder according to claim 9,
The method for producing a dispersion of ceramic powder, wherein the radical species is OH · and / or H ·. A method for producing a dispersion of ceramic powder according to any one of claims 6 to 10,
A method for producing a dispersion of a ceramic powder, comprising adding a dispersant to the dispersion medium after applying a voltage between the pair of electrodes.

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