JPH10330166A - Production of ceramic molding product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the ununiformity of component distribution caused by difference in density in producing a ceramic molding product by using silicon nitride (Si3 N4 ) as a ceramic material and adding alumina (Al2 O3 ) and yttria (Y2 O3 ) as a metal oxide-based sintering auxiliary to the silicon nitride. SOLUTION: A porous molding product F composed of silicon nitride, having a uniform component distribution is molded and aluminum nitrate (Al(NO3 )3 ) and yttrium nitrate (Y(NO3 )3 ) as alumina and yttria derivatives are penetrated into the voids of the molding product F in a state of a solution L dissolved in ethanol by vacuum. Then the molding product F is dried to precipitate each nitrate and then heated in an oxidizing atmosphere to form alumina and yttria composed of nitrates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic molded product, and more particularly to a method for dispersing and adding a metal oxide sintering aid to a ceramic material and its application.

[0002]

2. Description of the Related Art In general, a ceramic molded product is obtained by molding a powdery ceramic material into a porous molded body having a predetermined shape and sintering it.

By the way, as a method of forming the above-mentioned molded body, there is known a method of using a slurry in which the above-mentioned ceramic material is dispersed in a solution, such as a doctor blade method or a compression molding method. And so on. On the other hand, the inventor of the present invention has filed an earlier
No. 65505) proposes a new molding method called a high-speed centrifugal molding method.

That is, in the high-speed centrifugal molding method described above, a metal mold having a cavity of a predetermined shape is used, in which a storage portion capable of storing the slurry and communicating with the cavity is connected. Then, the mold is set in a centrifuge and rotated at a high speed so that centrifugal force of several tens to several hundred thousand times of gravity is applied, thereby centrifuging the slurry in the reservoir into a solid component and a liquid component. It is separated and only the solid component is filled into the cavity of the mold, while the liquid component remains in the reservoir. According to this, a compact having a high particle filling rate and high surface finish accuracy can be easily molded in a short time.

[0005]

However, in the above proposed example, the ceramic material is, for example, alumina (Al).
_In the case of silicon nitride which requires the addition of a metal oxide sintering aid such as ₂ O ₃ ) or yttria (Y ₂ O ₃ ), the sedimentation speed of these ceramic materials and sintering aids differs depending on the density. Therefore, there is a disadvantage that it is difficult to make the component distribution of the molded body uniform. Specifically, since molding starts at a portion far from the center of rotation of the centrifuge, a component having a high density is concentrated on a portion to be formed first, and a component having a low density is closer to the center of rotation. Increase.

[0006] The above-described density segregation occurs not only when a sintering aid is added but also when a plurality of types of ceramic materials having different densities are used in combination.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a powdery ceramic material, and a metal oxide-based sintering additive dispersed and added to the ceramic material. When manufacturing a ceramic molded article composed of a metal oxide such as the one described above, by devising the method of adding the metal oxide, it is possible to eliminate non-uniform component distribution due to a difference in density. It is in.

[0008]

In order to achieve the above-mentioned object, according to the present invention, a porous compact having no density segregation is formed by using only a ceramic material.
A solution in which nitrate as a derivative thereof was dissolved in a solvent was infiltrated into the voids of the molded article and added to the molded article.

Specifically, the invention of claim 1 presupposes a method of manufacturing a ceramic molded product comprising a powdery ceramic material and a metal oxide dispersed and added to the ceramic material. Then, first, a porous molded body is formed using the ceramic material. Thereafter, a solution in which nitrate as a derivative of the metal oxide is dissolved in a solvent is infiltrated into the voids of the molded body. Next, the nitrate is precipitated in the void by drying the compact. Thereafter, the metal oxide is generated from the nitrate in the void by heating the compact in an oxidizing atmosphere (for example, in the air). In the above configuration, a porous formed body is formed from the ceramic material, and then the solution penetrates into the voids of the formed body.
In this solution, nitrate as a metal oxide derivative to be added to the ceramic material is dissolved in a solvent,
When the solvent evaporates by drying the molded body, the nitrate precipitates in the voids of the molded body. At this time, as the solvent evaporates, the nitrate is uniformly diffused and precipitated due to the surface tension. Thereafter, when the molded body is heated in an oxidizing atmosphere, the nitrate is decomposed, the nitric acid component is removed, and the remaining metal is oxidized to generate the metal oxide. At that time, the nitrate
In general, it has the property of being very well soluble in solvents (water, alcohol, etc.), so that uniform deposition is properly performed in the voids of the molded body, and the above-mentioned production operation is repeated due to the large amount of metal oxide added. If it is necessary to perform this operation only a small number of repetitions is required.

[0010] According to a second aspect of the present invention, in the first aspect of the present invention, the molded body is molded by using a slurry in which a single type of ceramic material is dispersed in a solvent.
In the above configuration, when a molded body is formed by the slurry of the ceramic material, if the slurry contains materials having different densities, the sedimentation speed varies depending on the density. At this time, since the slurry is made of a single type of ceramic material, such a difference in sedimentation speed does not occur, and thus a molded body having a uniform component distribution can be obtained.

According to a third aspect of the present invention, in the second aspect of the present invention, the molded body is molded by a high-speed centrifugal molding method. In the above configuration, since the compact is formed by high-speed centrifugal molding using a slurry of ceramic material, a compact having a high particle filling rate and a high surface finish accuracy can be easily formed in a short time. . At this time, since the slurry is made of a single ceramic material, density segregation due to the difference in material density occurs despite the centrifugal force of several thousand to tens of thousands times the gravity applied to the slurry. Without this, a molded product having a uniform component distribution can be obtained.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the molded body is molded using a ceramic material to which a binder is added. In the above configuration,
Since the molded article is molded using the ceramic material to which the binder has been added, decomposition of the molded article in the solution is suppressed.

According to a fifth aspect of the present invention, in the first aspect of the invention, the molded body is obtained by forming a ceramic material into a predetermined shape and then calcining the molded body. In the above configuration, since the molded body is obtained by forming the ceramic material into a predetermined shape and then pre-firing, also in the present invention, the decomposition of the molded body in the solution can be suppressed.

According to a sixth aspect of the present invention, in the first aspect, a metal oxide-based sintering aid is added as the metal oxide. In the above configuration, since a metal oxide-based sintering aid (for example, alumina or yttria) is added to the ceramic material as a metal oxide, the sintering aid is uniformly dispersed in the voids of the compact. Will be done. Therefore, when a ceramic material requiring a sintering aid for sintering such as silicon nitride is used, a ceramic molded article without density segregation can be obtained properly.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, while silicon nitride is used as the ceramic material, alumina and yttria are added as metal oxide-based sintering aids. In the above configuration, while silicon nitride is used as the ceramic material, alumina and yttria are added as metal oxide-based sintering aids. Therefore, a ceramic molded product made of silicon nitride that requires alumina and yttria as a sintering additive and has no density segregation is specifically obtained.

According to an eighth aspect of the present invention, in the first aspect, a metal oxide-based ceramic material different from the ceramic material is added as the metal oxide. In the above configuration, since a metal oxide-based ceramic material of a different type from the ceramic material is added to the ceramic material as a metal oxide, another ceramic material is uniformly dispersed in the voids of the molded body. Will be done. Therefore, a ceramic molded article without density segregation can be obtained using a plurality of types of ceramic materials having different densities.

According to a ninth aspect of the present invention, in the eighth aspect of the present invention, alumina is used as the ceramic material, and zirconia is added as a metal oxide-based ceramic material different from the ceramic material. . In the above configuration, alumina is used as a ceramic material, and zirconia is added as a metal oxide-based ceramic material different from the ceramic material. Accordingly, a ceramic molded product made of an alumina-zirconia composite material without density segregation is specifically obtained.

According to a tenth aspect of the present invention, in the first aspect of the present invention, when the ceramic material is a metal oxide-based material, unlike the case of the eighth aspect of the present invention, the same type of Is added as a metal oxide. In the above configuration, the same type of ceramic material as the ceramic material is added to the metal oxide-based ceramic material as a metal oxide. The ceramic material will be evenly dispersed. Thereby, the packing density of the ceramic material can be increased irrespective of the firing temperature during sintering, so that the crystal grains can be reduced by lowering the firing temperature,
A high-strength ceramic molded product can be obtained.

In the eleventh aspect, in the tenth aspect, the metal oxide ceramic material is
Use alumina. In the above configuration, since alumina is used as the metal oxide-based ceramic material, a high-strength ceramic molded article made of alumina is specifically obtained.

According to a twelfth aspect of the present invention, in the first aspect of the present invention, the molded body is sealed in a state of being immersed in a solution, and the gas in the void of the molded body is discharged by evacuation to form a gas in the void. Soak the above solution. In the above configuration, when the molded body is sealed and evacuated in a state of being immersed in the solution, the gas in the void of the molded body is discharged to the outside through the solution. The solution will penetrate into the void. Therefore, the solution enters the gap properly.

According to a thirteenth aspect of the present invention, in the first aspect of the present invention, a centrifugal force is applied to the molded body and the solution so that the solution passes through the cavity of the molded body, and gas in the cavity is combined with the solution. To be replaced. In the above configuration, the gas in the voids of the molded body is replaced with the solution by applying centrifugal force to the molded body and the solution. Therefore, also in the present invention, the solution is properly penetrated into the voids. .

In a fourteenth aspect of the present invention, in the first aspect of the present invention, the solution is pressurized and penetrates into the voids of the molded body. In the above configuration, the infiltration of the solution into the void of the molded body is performed by applying pressure. At this time, the gas in the gap hinders the infiltration of the solution, but the solution that has entered the gap adheres to the surface of the gap, so that the solution penetrates into the gap by an amount corresponding to the attached amount. Therefore, also in the present invention, the infiltration of the solution into the gap is properly performed.

In the method of manufacturing a ceramic according to a fifteenth aspect of the present invention, first, a formed body is formed by using a metal oxide-based ceramic material, pre-fired, and post-processed on the formed body. Thereafter, a solution in which a nitrate as a derivative of the ceramic material is dissolved in a solvent is infiltrated into a defective concave portion formed in the molded body due to the post-processing. Next, the formed body is dried to precipitate a nitrate in the defective recess. Thereafter, by heating the molded body in an oxidizing atmosphere, the ceramic material is generated from nitrate in the depressed concave portions to fill the depressed concave portions. In the above configuration, when a post-processing such as a cutting process is performed on a formed body formed of a metal oxide-based ceramic material, a minute defective concave portion is generated in the formed body with the subsequent processing.
Then, the solution infiltrates into the above-mentioned defective concave portion. In this solution, nitrate as a derivative of the ceramic material is dissolved in a solvent, and when the solvent is evaporated by drying the molded body, the nitrate precipitates in the voids of the molded body. . At this time, as the solvent evaporates, the nitrate is uniformly diffused and precipitated due to the surface tension. Thereafter, when the molded body is heated, the nitrate is decomposed and its nitric acid component is removed, and the remaining metal is oxidized to form the ceramic material. It will be filled with the same ceramic material.

According to a sixteenth aspect of the present invention, in the fifteenth aspect, the metal oxide ceramic material is
Use alumina. In the above configuration, since alumina is used as the metal oxide-based ceramic material, an alumina ceramic molded product having few defective concave portions due to post-processing after molding is specifically obtained.

According to a seventeenth aspect of the present invention, in accordance with the fifteenth aspect, the molded body is sealed in a state of being immersed in a solution, and the gas in the recessed portion of the molded body is discharged by vacuum evacuation. The solution is allowed to enter the recess. In the above configuration, when the molded body is sealed and evacuated while being immersed in the solution, the gas in the defective recess of the molded body is discharged to the outside through the solution, and accordingly, The solution penetrates into the defective recess.
Therefore, as in the case of the twelfth aspect of the invention, the infiltration of the solution into the defective recess is properly performed.

According to an eighteenth aspect of the present invention, in the above-mentioned fifteenth aspect, the solution is pressurized and penetrates into the defective concave portion of the molded body. In the above configuration, the infiltration of the solution into the defective concave portion of the molded body is performed by applying pressure. Therefore, as in the case of the fourteenth aspect of the present invention, the solution can be properly penetrated into the defective concave portion.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) A method of manufacturing a ceramic ball according to Embodiment 1 of the present invention will be described. In this embodiment,
Using silicon nitride (Si ₃ N ₄ ) as ceramic material,
By adding 2 wt% and 5 wt% of alumina (Al ₂ O ₃ ) and yttria (Y ₂ O ₃ ), which are metal oxide-based sintering aids, to the silicon nitride, respectively, a ceramic made of silicon nitride is used. Manufacture balls.

First, using a slurry S obtained by dispersing silicon nitride in ethanol as a solvent, a porous material having a uniform component distribution (for example, a particle filling rate of about 60% and a remaining
% Is a void). In particular,
As shown in FIG. 1, it has a cylindrical shape and has a slurry S at one end.
Is provided, and a dividable mold 1 having a cavity 3 on the other end side is used.
The storage chamber 2 is provided with a supply port 4 for supplying the slurry S into the storage chamber 2, and the supply port 4 is opened and closed by an opening / closing lid (not shown). Further, the storage chamber 2 is provided between the storage chamber 2 and the cavity 3.
Is provided with a small-diameter passage 5 which communicates with the first passage. Then, the mold 1 is accommodated in the centrifuge 6 and rotated at a high speed in a horizontal plane, whereby the slurry S in the storage chamber 2 is centrifuged into a solid component and a liquid component, and only the solid component is placed in the cavity 3. The molded body F is obtained by allowing the liquid component to remain in the storage chamber 2 while being filled. At this time, since the sintering aid is not added to the slurry S, a compact F having a uniform component distribution is obtained.

Next, aluminum nitrate (Al (NO
₃ ) A solution L in which these nitrates are dissolved in ethanol as a solvent is prepared using ₃ ) and yttrium nitrate (Y (NO ₃ ) ₃ ). Then, as shown in FIG. 2, the solution L is put in a desiccator 7, and the molded body F is preliminarily calcined (for example, 800 to 1000 ° C.), and then sealed while being immersed in the solution L in the desiccator 7. Then, vacuum evacuation (for example, about 1 Torr) is performed by the vacuum pump 8. At this time, since the molded body F has been calcined, it does not decompose in the solution L. Then, the compact F
The air in the gap is discharged, whereby the solution L enters the gap.

Next, the inside of the desiccator 7 is returned to the atmospheric pressure, the molded body F is taken out, dried, and the ethanol in the solution L is evaporated. Thereby, aluminum nitrate and yttrium nitrate are precipitated in the voids of the molded body F, respectively. At this time, as the ethanol evaporates, aluminum nitrate and yttrium nitrate are uniformly diffused and precipitated by the surface tension of the ethanol, so that they are uniformly dispersed in the compact F.

Thereafter, the compact F is heated in an oxidizing atmosphere (for example, in the air). As a result, aluminum nitrate and yttrium nitrate are decomposed to remove the respective nitric acid components, and the remaining aluminum and yttrium are oxidized to form alumina and yttria as metal oxides in the voids. The concentration of the solution L is
When alumina and yttria are produced, the production amount, that is, the addition amount is adjusted to be 2 wt% and 5 wt%, respectively. At this time, since aluminum nitrate and yttrium nitrate are very well dissolved in ethanol, when the amount of added alumina and yttria is large and it is necessary to repeat the infiltration and heating of the solution L, the predetermined amount can be reduced with a small number of repetitions. Alumina and yttria are added. Thereafter, by firing the compact F, silicon nitride as a ceramic material is appropriately sintered, and a ceramic ball is obtained.

Therefore, according to this embodiment, when a ceramic ball is manufactured by using silicon nitride as a ceramic material and adding alumina and yttria which are sintering aids of a metal oxide to this silicon nitride, After forming a porous molded body F having a uniform component distribution using the above-mentioned silicon nitride slurry S, a solution L of aluminum nitrate and yttrium nitrate is introduced into the voids of the molded body F, and then molded. The body F is dried to precipitate each nitrate in the void,
Thereafter, alumina and yttria were formed from the nitrates, respectively, so that the alumina and yttria could be uniformly dispersed in the molded body F,
Thus, the compact F made of silicon nitride can be appropriately sintered.

At this time, since the compact F is formed by the high-speed centrifugal molding method, the compact F having a high particle filling rate and high surface finish accuracy can be formed.

Further, since the molded body F is preliminarily calcined and then immersed in the solution L, the molded body F is immersed in the solution L.
Can be prevented from decomposing.

Further, the molded body F is sealed in a state of being immersed in the solution L, and the gas in the voids of the molded body F is exhausted by evacuation to thereby allow the solution L to enter the voids. Therefore, it is possible to properly infiltrate the solution L into the gap.

In the first embodiment, silicon nitride is used as the ceramic material. However, other ceramic materials such as silicon carbide (SiC) may be used.

In the first embodiment, alumina and yttria are added as sintering aids, but the sintering aid can be appropriately set according to the ceramic material used for the molded body.

Further, in the first embodiment, ethanol is used as the solvent for dissolving the nitrate, but water or other alcohol can be used as long as the nitrate can be dissolved.

(Embodiment 2) A method of manufacturing a ceramic ball according to Embodiment 2 of the present invention will be described. In the present embodiment, alumina is used as the ceramic material of the compact F, and zirconia (Z), which is a metal oxide-based ceramic material of a different type from that of the compact F, is used as the alumina.
rO ₂ ) by adding only 10 wt%, alumina
A ceramic ball made of a zirconia composite material is manufactured. In the description of the present embodiment, the first embodiment will be described.
The same parts as in the case of are denoted by the same reference numerals.

First, a binder is added to the alumina to form a slurry S, and a molded body F is formed from the slurry S by the same high-speed centrifugal molding method as in the first embodiment and dried. On the other hand, zirconium nitrate (Zr (NO ₃ ) ₄ ) as a derivative of zirconia is dissolved in ethanol to prepare a solution L, and the solution L is placed in the desiccator 7.
Then, the molded body F is immersed in the solution L in the desiccator 7, and the solution L is immersed in the gap of the molded body F by evacuating in a sealed state.

Next, the molded body F is taken out of the desiccator 7 and dried to evaporate ethanol in the solution L. As a result, zirconium nitrate precipitates in the voids of the compact F.

Thereafter, the compact F is heated in an oxidizing atmosphere (for example, in the air). Thereby, the nitric acid component of the zirconium nitrate is separated, and the remaining zirconium is oxidized to form zirconia. This allows
This means that zirconia was added to the voids of the compact F made of alumina. The amount (concentration) of zirconium nitrate in ethanol is set so that the amount of zirconia added to the molded body F is 10 wt%. When it is necessary to increase the amount of zirconia added (for example, several tens wt.
%), The steps from infiltration of the solution L to heating are repeated as many times as necessary. Thereafter, by firing the molded body F,
A ceramic ball made of an alumina-zirconia composite material is obtained.

Therefore, according to the present embodiment, when manufacturing a ceramic ball made of an alumina-zirconia composite material, first, a compact F is formed using alumina slurry S, and then the compact F is formed. The solution L of zirconium nitrate is infiltrated into the voids, and then the molded body F is dried to precipitate zirconium nitrate in the voids.
Since zirconia is generated from the zirconium nitrate, it is possible to obtain a ceramic ball without density segregation made of an alumina-zirconia composite material by uniformly adding zirconia to alumina. As compared with the case, the properties as a ceramic molded product can be improved.

In the second embodiment, the case where alumina and zirconia are combined is described, but other ceramic materials may be combined.

In the second embodiment, the case where two types of ceramic materials are combined has been described.
More than one type of ceramic material can be combined.

(Embodiment 3) A method of manufacturing a ceramic ball according to Embodiment 3 of the present invention will be described. In the present embodiment, alumina is used as a metal oxide-based ceramic material, and alumina is added again to the voids of the formed body F made of alumina, thereby producing a ball having a high packing density of alumina. In the description of the present embodiment, the same portions as those in the first embodiment are denoted by the same reference numerals.

First, a binder is added to alumina as the ceramic material to form a slurry S, and a compact F is obtained and dried by the same high-speed centrifugal molding method as in the first embodiment. On the other hand, aluminum nitrate as a derivative of alumina is dissolved in ethanol to prepare a solution L, and the solution L is put into the desiccator 7. Then, the molded body F is immersed in the solution L in the desiccator 7 and evacuated in a sealed state, whereby the solution L enters the gap of the molded body F.

Next, the compact F is taken out of the desiccator 7 and dried to evaporate the ethanol in the solution L. Thereby, aluminum nitrate precipitates in the voids of the molded body F.

Thereafter, by heating the compact F in an oxidizing atmosphere (for example, in the air), the aluminum nitrate is decomposed to remove the nitric acid component, and the remaining aluminum is oxidized. Small alumina particles are generated between the particles of alumina forming F. Thereby, the packing density of alumina becomes higher than in the conventional case. Thereafter, by firing the molded body F, a ceramic ball using alumina as a ceramic material is obtained.
At this time, since the packing density of alumina is high, conventionally, to obtain a high packing density, a high temperature (for example, 1230) is used.
C.), but it can be fired at a lower temperature (for example, 1150-1170 ° C.), so that the size of alumina crystal grains is about half that of the conventional case, and as a result, The strength is increased by about 50% as compared with the case of firing at 1230 ° C.

Therefore, according to the present embodiment, when a ceramic ball using alumina as a ceramic material is manufactured, the compact F is formed using the slurry S of alumina, Aluminum nitrate solution L
Then, the molded body F is dried to precipitate aluminum nitrate in the voids. Thereafter, alumina is generated from the aluminum nitrate. Therefore, even if the firing temperature is low, the packing density of alumina is increased. As a result, it is possible to obtain a high-strength ceramic ball by firing at a lower temperature than in the conventional case.

Although the third embodiment has described the case where alumina is used as the metal oxide-based ceramic material, other ceramic materials can be used.

Embodiment 4 A method for manufacturing a ceramic ball according to Embodiment 4 of the present invention will be described. In the present embodiment, the compact F is formed of alumina, and the compact F is subjected to post-processing and then fired to form a ceramic ball. In the description of the present embodiment, the same portions as those in the first embodiment are denoted by the same reference numerals.

First, a slurry S of the above-mentioned alumina and the binder was prepared, and a compact F was obtained and dried by the same high-speed centrifugal molding method as in the first embodiment. The grinding process is performed.

On the other hand, aluminum nitrate as a derivative of alumina is dissolved in ethanol to prepare a solution L, and this solution L is placed in the desiccator 7. Then, the molded body F is immersed in the solution L in the desiccator 7 and evacuated in a sealed state. As a result, the solution L penetrates into the minute concave recesses formed on the surface of the molded body F due to the grinding.

Next, the molded body F is taken out of the desiccator 7 and dried to evaporate ethanol in the solution L. As a result, aluminum nitrate precipitates in the recessed portions of the molded body F.

Thereafter, by heating the compact F in an oxidizing atmosphere (for example, in the atmosphere), the aluminum nitrate is decomposed to separate the nitric acid component, and the remaining aluminum is oxidized to produce alumina. As a result, the defective concave portion is filled with alumina. afterwards,
By firing the formed body F, a ceramic ball which is subjected to grinding and has few concave portions due to the grinding can be obtained.

Therefore, according to the present embodiment, when the molded body F made of alumina is subjected to post-processing to produce a ceramic ball, aluminum nitrate is placed in the defective concave portion of the molded body F which has been subjected to the subsequent processing. The solution L was infiltrated, and then the molded body F was dried to precipitate aluminum nitrate in the defective concave portions. Thereafter, alumina was generated from the aluminum nitrate to fill the defective concave portions.
Despite the post-processing, it is possible to obtain a ceramic ball having a small number of concave portions caused by the subsequent processing.

In each of the above embodiments, the compact F is formed by the high-speed centrifugal molding method using the slurry S of the ceramic material, but may be formed by other known molding methods. Good.

Further, in each of the above-described embodiments, the solution L is evacuated to penetrate into the voids or the depressed concave portions of the molded body F. However, the vacuuming may be performed by other methods. For example, as shown in FIG. 3, an immersion chamber 11 for storing the solution L and accommodating the molded body F is provided at one end (upper end in FIG. 3), while the other end (lower end in FIG. 3) is provided. ), A drainage path 12 for communicating the bottom of the immersion chamber 11 to the outside.
A centrifugal force may be applied to the device with one end of the device facing the inner periphery and the other end facing the outer periphery. Further, as another example, as shown in FIG. 4, the solution L may be put in the container 21 and the molded body F may be immersed in the solution L and pressurized as shown by an arrow in the same figure.

Further, in each of the above embodiments, the case where a ceramic ball is manufactured has been described. However, it goes without saying that the present invention can be applied to the manufacture of other ceramic molded products.

[0061]

As described above, according to the first aspect of the present invention, there is provided a method for manufacturing a ceramic molded product comprising a powdery ceramic material and a metal oxide dispersed and added to the ceramic material. After forming a porous molded body with the ceramic material, a solution in which a nitrate as a derivative of the metal oxide is dissolved in a solvent is infiltrated into the voids of the molded body, and then the molded body is dried. Precipitating the nitrate in the voids, and then producing the metal oxide from the nitrate, it is possible to uniformly disperse the metal oxide in a molded body made of a ceramic material,
A ceramic molded article without density segregation can be obtained.

According to the second aspect of the present invention, the molded body is
Since the molding is performed using a single type of ceramic material slurry, density segregation due to a difference in sedimentation speed in the slurry can be avoided, and the effect of the invention of claim 1 described above is properly obtained. be able to.

According to the third aspect of the present invention, the molded body is
Since the molding is performed by the high-speed centrifugal molding method, it is possible to obtain a ceramic molded product having a high packing density and a high surface finish accuracy and a uniform component distribution.

According to the fourth aspect of the present invention, the molded body is
Since the molding is performed using the ceramic material to which the binder is added, the molded body can be prevented from being decomposed in the solution, and the solution can appropriately enter the voids of the molded body.

According to the invention of claim 5, the molded article is
Since the ceramic material is formed into a predetermined shape and then pre-fired, the present invention can also prevent the decomposition of the molded body in the solution and properly infiltrate the solution into the voids. it can.

According to the sixth aspect of the present invention, since a metal oxide-based sintering aid is added as the metal oxide, the sintering aid can be evenly dispersed in the compact. Thus, when a ceramic is produced using a ceramic material requiring a sintering aid, the compact can be properly sintered.

According to the seventh aspect of the present invention, while silicon nitride is used as the ceramic material, alumina and yttria are added as metal oxide-based sintering aids. No ceramic moldings can be specifically obtained.

According to the eighth aspect of the present invention, since a metal oxide-based ceramic material different from the ceramic material is added as the metal oxide, a ceramic molding made of a composite material without density segregation is added. Goods can be obtained.

According to the ninth aspect of the present invention, while alumina is used as the ceramic material, zirconia is added as a metal oxide-based ceramic material different from the ceramic material. A ceramic molded article made of a composite material without density segregation can be specifically obtained.

According to the tenth aspect, when the ceramic material is a metal oxide-based material, the same type of ceramic material as the ceramic material is added as a metal oxide. It is possible to increase the packing density of the ceramic material without increasing the temperature, and as a result, it is possible to obtain a high-strength ceramic molded product by firing at a lower temperature than in the conventional case to reduce crystal grains.

According to the eleventh aspect, since alumina is used as the metal oxide-based ceramic material, a high-strength ceramic molded article made of alumina can be specifically obtained.

According to the twelfth aspect of the present invention, the solution is immersed in the solution by evacuating the molded body while the molded body is immersed in the solution. It can be properly infiltrated.

According to the thirteenth aspect of the present invention, the solution is penetrated into the cavity by applying a centrifugal force to the molded body and the solution so that the solution passes through the cavity. According to the invention as well, the solution can be specifically and appropriately penetrated into the voids of the molded body.

According to the fourteenth aspect of the present invention, since the solution is pressurized and penetrates into the voids of the molded body, the present invention also specifically prevents the solution from entering the voids of the molded body. Can do it.

According to the method of manufacturing a ceramic according to the fifteenth aspect of the present invention, a formed body is formed from a metal oxide-based ceramic material, preliminarily fired, the formed body is subjected to post-processing, A solution in which nitrate as a derivative of the ceramic material is dissolved in a solvent is infiltrated into the recessed recesses formed in the molded body with the, and then the molded body is dried to precipitate nitrate in the recessed recesses. Since the above-mentioned ceramic material is generated from the nitrate to fill the defective concave portions, fine defective concave portions generated in the molded body due to post-processing such as cutting can be filled with the same type of ceramic material. It is possible to obtain a ceramic molded product having few defective concave portions due to post-processing.

According to the sixteenth aspect of the present invention, alumina is used as the metal oxide-based ceramic material, so that an alumina ceramic molded product having few defective concave portions due to post-processing after molding is specifically obtained. be able to.

According to the seventeenth aspect of the present invention, the solution is immersed in the concave recess by vacuuming while the molded body is immersed in the solution. In addition, the solution can specifically and appropriately penetrate into the defective concave portion of the molded body.

According to the eighteenth aspect of the present invention, the solution is pressurized and penetrates into the defective concave portion of the molded body. The infiltration of the solution into the liquid can be specifically performed.

According to the nineteenth aspect, a ceramic molded product manufactured by the method for manufacturing a ceramic molded product according to each of the above inventions can be specifically obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing an instrument and a centrifuge used for high-speed centrifugal molding in a method for manufacturing a ceramic ball according to a first embodiment of the present invention.

FIG. 2 is a schematic view showing a state in which a solution is infiltrated into a void of a molded body by evacuation.

FIG. 3 is a cross-sectional view showing an instrument used when a solution is caused to enter a gap of a molded article by centrifugal force.

FIG. 4 is a schematic view showing another method for infiltrating a solution into a void of a molded body.

[Explanation of symbols]

 S Sludge F Molded L Solution

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C04B 38/04 C04B 35/58 102S

Claims (19)

[Claims] 1. A method for producing a ceramic molded article comprising a powdery ceramic material and a metal oxide dispersed and added to the ceramic material, wherein a porous molded body is formed using the ceramic material. After molding, a solution in which nitrate as a derivative of the metal oxide is dissolved in a solvent is infiltrated into the voids of the molded body, and then the nitrate is precipitated in the voids by drying the molded body. A method for producing a ceramic molded product, comprising heating the molded body in an oxidizing atmosphere to generate the metal oxide from the nitrate in the void. 2. The method for producing a ceramic molded product according to claim 1, wherein the molded product is molded using a slurry in which a single type of ceramic material is dispersed in a solvent. Manufacturing method. 3. The method for producing a ceramic molded product according to claim 2, wherein the molded product is molded by a high-speed centrifugal molding method. 4. The method for producing a ceramic molded product according to claim 1, wherein the molded product is molded using a ceramic material to which a binder has been added. Method. 5. The method for producing a ceramic molded product according to claim 1, wherein the molded product is obtained by forming a ceramic material into a predetermined shape and then pre-baking the molded product. 6. The method for producing a ceramic molded product according to claim 1, wherein a metal oxide-based sintering aid is added as the metal oxide. 7. The method of manufacturing a ceramic molded product according to claim 6, wherein silicon nitride is used as the ceramic material, and alumina and yttria are added as metal oxide sintering aids. Manufacturing method of molded article. 8. The method for producing a ceramic molded product according to claim 1, wherein a metal oxide-based ceramic material of a type different from the ceramic material is added as the metal oxide. Method. 9. The method for producing a ceramic molded product according to claim 8, wherein alumina is used as the ceramic material, and zirconia is added as a metal oxide-based ceramic material different from the ceramic material. Manufacturing method of a ceramic molded product. 10. The method for manufacturing a ceramic molded product according to claim 1, wherein a metal oxide-based ceramic material is used as the ceramic material, and a ceramic material of the same type as the ceramic material is added as the metal oxide. A method for producing a ceramic molded product, characterized by comprising: 11. The method for producing a ceramic molded product according to claim 10, wherein alumina is used as the metal oxide-based ceramic material. 12. The method for manufacturing a ceramic molded article according to claim 1, wherein the molded body is sealed in a state where the molded body is immersed in a solution, and the gas in the void of the molded body is discharged by vacuum evacuation. A method for producing a ceramic molded product, comprising infiltrating the above solution into a ceramic molded product. 13. The method for manufacturing a ceramic molded product according to claim 1, wherein a centrifugal force is applied to the molded body and the solution so that the solution passes through the cavity of the molded body, and the gas in the cavity is combined with the solution. A method for producing a ceramic molded product, wherein the method comprises substituting. 14. The method for producing a ceramic molded article according to claim 1, wherein the solution is pressurized and penetrated into the voids of the molded article. 15. A molded body is formed using a metal oxide-based ceramic material, preliminarily baked, post-processed on the formed body, and a depressed recess formed in the formed body with the post-processing. Within
A solution obtained by dissolving a nitrate as a derivative of the ceramic material in a solvent is infiltrated, and then, the molded body is dried to precipitate the nitrate in the defective concave portion. A method for producing a ceramic molded product, wherein the ceramic material is generated from the nitrate in the defective concave portion by heating in the defective concave portion to fill the defective concave portion. 16. The method for producing a ceramic molded product according to claim 15, wherein alumina is used as the metal oxide-based ceramic material. 17. The method for producing a ceramic molded article according to claim 15, wherein the molded article is sealed in a state of being immersed in a solution, and the gas is exhausted from the recessed portion of the molded article by vacuum evacuation. A method for producing a ceramic molded product, comprising infiltrating the solution into a concave portion. 18. The method for producing a ceramic molded product according to claim 15, wherein the solution is pressurized and penetrates into a concave recess of the molded product. 19. The method of claim 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15, 16,
19. A ceramic molded article produced by the method for producing a ceramic molded article according to 17 or 18.