JP7016610B2 - Porous ceramics manufacturing method and porous ceramics - Google Patents

Description

The present invention relates to porous ceramics, particularly porous ceramics having pores.

Various ceramics have been manufactured conventionally, but ceramics having pores on the surface of the ceramics have been used for various purposes. The size of the pores and the degree of penetration vary depending on the application of the applied product, but it has been difficult to manufacture ceramics having submicron pores or nano-level diameter pores.

As a method for producing porous ceramics, a method in which a large amount of a pore-forming agent such as a deflocculant or a resin bead is added to the ceramic powder and oxidatively removed to make the porous ceramic powder is common. However, there is a problem that it is difficult to obtain continuous open pores because the pores exist in isolation even if the pores are removed. Further, a method of adhering ceramic slurry to a flexible polyurethane foam without a cell film and sintering it (Patent Document 1), a method of adding a ceramic raw material and a deflocculant as an aqueous solution, and then adding a foam material for sintering. A method for doing so (Patent Document 2) has also been proposed. However, these manufacturing methods have a problem that porous ceramics having submicron pores or nano-level diameter pores cannot be obtained.

JP-A-6-239673 JP-A-63-40782

An object of the present invention is to produce a product having pores having a diameter of about several tens of nanometers from a submicron diameter and having pores penetrating the inside of a ceramic block with good controllability.

In order to solve the above problems, as the first invention, there is an intermediate step between a preparation step of preparing a combustion vaporization material and a ceramic raw material and a kneading step of kneading the prepared combustion vaporization material and the ceramic raw material to obtain an intermediate. Provided is a method for producing a porous ceramic, comprising a firing step for calcining a body or / and an intermediate derivative to burn and vaporize the combustion vaporized material to obtain a ceramic having a large number of pores.

Further, in the first invention, the combustion vaporizing material provides a second invention in which the maximum diameter is submicron.

Further, in the first invention and the second invention, there is provided a third invention having a drug impregnation step of impregnating the porous ceramics obtained in the firing step with a drug.

Further, as a fourth invention, an intermediate for producing a porous ceramic in which a combustion vaporizing material is uniformly dispersed in a ceramic raw material is provided.

Further, as the fifth invention, the combustion vaporized material is uniformly contained in the ceramic raw material obtained by blocking the intermediate of the fourth invention, drying the blocked material, and crushing and grinding the dried material. Provided are intermediate derivatives for producing dispersed porous ceramics.

Further, as a sixth invention, there is provided a porous ceramic having pores in which the combustion vaporized material filled by firing can be discharged to the outside even when the pores are filled with the combustion vaporized material.

Further, in the sixth invention, the seventh invention provides the seventh invention in which the pores include pores having a submicron diameter.

It is possible to produce a product having pores having a diameter of about several tens of nanometers from a submicron diameter and having pores penetrating the inside of a ceramic block with good controllability.

The flow chart which shows the manufacturing method of the porous ceramics of Embodiment 1. The flow chart which shows the manufacturing method of the porous ceramics of Embodiment 1. Diagram explaining the maximum diameter The figure which shows the pore distribution, the physical property value and the microstructure of a porous ceramic The figure which shows the pore distribution, the physical property value and the microstructure of a porous ceramic The figure which shows the pore distribution, the physical property value and the microstructure of a porous ceramic The figure which shows the pore distribution, the physical property value and the microstructure of a porous ceramic The figure which shows the pore distribution, the physical property value and the microstructure of a porous ceramic

Hereinafter, embodiments for carrying out the invention will be described. The present invention should not be construed as being limited to the embodiments described below. The relationship between the embodiment and the claims is as follows. The first embodiment mainly relates to claims 1 to 5, and the like. The second embodiment mainly relates to claims 6 and 7.
<Embodiment 1>
<Overview>

This embodiment is a method for manufacturing porous ceramics, and its characteristic feature is that a combustion vaporized material is mixed with a ceramic raw material in advance and kneaded (also referred to as “kneading”; the same applies hereinafter) to manufacture ceramics. be.
<Structure>

FIG. 1 is a flow chart showing a method for producing porous ceramics according to this embodiment. The configuration of this embodiment includes a preparation step (S0101), a kneading step (S0102), and a firing step (S0103).

FIG. 2 is another flow chart showing a method for producing the porous ceramics of the present embodiment. In this embodiment, based on FIG. 1, the porous ceramics obtained by the preparation step (S0201), the kneading step (S0202) and the firing step (S0203) are impregnated with a chemical (S0204: chemical impregnation step), and the chemical is applied. This is a method for producing porous ceramics, which obtains ceramics having a large number of impregnated pores. Each configuration and examples will be described in detail below.
<Preparation step>

The preparation step is a step of preparing the combustion vaporization material and the ceramic raw material. The combustion vaporization material corresponds to cellulose, carbon material, and organic compound, but it is a material and refers to a solid material. Therefore, liquid and gel-like materials are not included in the combustion vaporization material. However, the material that looks macroscopically liquid or gel-like when the solid material is mixed with the liquid is the solid combustion vaporization material according to the present invention.

The essential feature of the embodiment having pores having a diameter of about several tens of nanometers from the submicron diameter, which is the subject of the present invention, and the pores penetrating the inside of the ceramic block depends on the shape and size of the combustion vaporizing material. The point is to obtain the porosity finally formed in the ceramic material. That is, the holes provided on the surface or inner surface of the ceramic material are controlled by the shape and size of the combustion vaporized material. Therefore, in the preparation step, preparation is performed assuming the size of the pores to be provided in the target porous ceramics, the amount of the pores, the density of the pores, and the like.

In addition, the shape of the ceramic raw material must be designed in advance in order to control the properties of the final porous ceramics. The design depends on the particle size, particle size distribution, and type of raw material.

Further, in the preparation stage, there may be a step of mixing the ceramic raw material and the combustion vaporization material and then further miniaturizing them with a ball mill or the like. This is preferable in that the particles of the ceramic raw material and the combustion vaporizing material are mixed while being miniaturized, and both are uniformly dispersed in the next kneading step.
<Kneading step>

In the kneading step, the prepared combustion vaporization material and the prepared ceramic raw material are kneaded. For example, the kneading may be carried out by adding a liquid, but if necessary, the pH of the liquid may be adjusted to be alkaline or acidic. This is adjusted according to the types of ceramic raw materials and combustion vaporization materials. In addition, it is necessary for the combustion vaporization material to play a role of a link so that the fine ceramic particles, which are ceramic raw materials, do not collapse. From this point as well, it is important to select the combustion vaporized material in the preparation step.

As the liquid, an organic liquid such as water or alcohol may be used for kneading. Further, water and an organic liquid such as alcohol may be used in combination for kneading. After kneading, liquids such as water and alcohol and the components used for kneading are excluded by drying. Drying rate is a controlled parameter. This is because the pressure and amount of gas generated from the combustion vaporized material at the time of firing or the pre-ceramic block after kneading and drying change depending on the degree of drying. The pressure of this gas and the amount of gas affect the size of the pores of the finally obtained porous ceramics, the amount of the pores, the density of the pores, and the degree of penetration of the pores.

When the size of the grains or the combustion vaporizing material, which are ceramic materials, is nano-sized (in this specification, a value of about 10 nanometers to 300 nanometers is referred to as nano-sized), it is difficult to disperse in the liquid, so that the surfactant is used. May be shared. However, it should be noted that the surfactant is also a factor that affects the firing. Preheating substeps may be employed as well as drying to eliminate the surfactant.

The kneading step may be performed using a tool such as a normal mixer, a propeller stirrer, a kneader, or the like, but when the material becomes a small size, it becomes difficult to knead sufficiently. Therefore, it is conceivable to apply ultrasonic waves or high-frequency electromagnetic fields to the kneading container. The high-frequency electromagnetic field can polarize the fine particles of the ceramic raw material depending on the controlled state, and is easily mixed with water. In addition, the same effect may be produced for the combustion vaporized material.

In the kneading step, intermediates can be obtained. The intermediate is in a state where the combustion vaporized material is uniformly dispersed in the ceramic raw material by the kneading step. The intermediate may be in the form of powder, liquid or slurry immediately after kneading, or may be in the form of a liquid or slurry and dried to form a block. The uniformly dispersed state is a state in which the combustion vaporization composition is inserted between the ceramic raw materials and the ceramic raw materials, and the amount and concentration of the combustion vaporization compositions existing around the ceramic raw materials are not biased. It is in a state.

The kneading step may include a sub-step in which a liquid or slurry is dried to form a block, which is then crushed again, and then kneaded again. In other words, another intermediate derived from this intermediate is obtained from the block of the intermediate produced by kneading. This other intermediate is referred to herein as an intermediate derivative.
<Baking step>

Baking is performed after the kneading step. The firing step has two meanings. One is that the fine particles of the ceramic raw material are locally melted and welded to each other to grow the ceramic particles, and that the pores that form the porous material are created. Therefore, in the firing step, the above two phenomena proceed at the same time. Normally, the combustion temperature of the combustion vaporized material is lower than the local melting temperature of the ceramics. Therefore, if the work (intermediate) is retained for a long time at a temperature at which the combustion vaporized material burns but the ceramic particles do not grow, the ceramic becomes non-porous.
<Drug impregnation step>

A chemical impregnation step can also be performed after the kneading step. The chemical impregnation step is a step of impregnating the porous ceramics obtained in the firing step with a chemical. The agent to be impregnated into the porous ceramics is not particularly limited, and examples thereof include catalysts, proteins, cells, and agents. The size of the holes, the amount of the holes, the density of the holes, and the degree of penetration of the holes are different depending on the chemical to be impregnated, but the present invention is a submicron finally formed on the ceramic material depending on the shape and size of the combustion vaporized material. Since the pores have a diameter of several tens of nanometers and the porosity of the pores penetrating the inside of the ceramic block can be controlled, the optimum porous ceramics can be produced according to the chemical to be impregnated. It becomes possible. The method of impregnating the chemical is not particularly limited, and examples thereof include an impregnation method, an ion exchange method, a vapor deposition method, and a spray drying method. If the pores are not sufficiently infiltrated with gas, liquid, etc. due to the surface tension of the liquid, etc. to be infiltrated, the high-pressure side and low-pressure side are made using the ceramics as a partition wall, and the gas, liquid, etc. are infiltrated using the pressure difference. ..
<Combustion vaporization material>

"Combustion vaporization material" is a material that is burnt and vaporized in the firing step. In the present invention, the combustion vaporizing material is not particularly limited, but is a material that is burnt vaporized in the firing step and disappears from the porous ceramics after firing.

FIG. 3 is a diagram illustrating a maximum diameter when the combustion vaporizing material is substantially columnar. In the case of an elongated shape such as a substantially cylinder, the maximum diameter is not the length in the longitudinal direction, but the maximum value (D1 in the figure) of the portion corresponding to the diameter of the cylinder is the maximum diameter. On the other hand, for example, if the combustion vaporizing material is substantially spherical, the maximum value of the portion corresponding to the diameter is the maximum diameter. It is desirable that the maximum diameter of the combustion vaporizing material of the present invention is submicron. The combustion vaporization material having a maximum diameter of submicron is not particularly limited, but for example, by using carbon fiber, crushed carbon fiber, or a material containing cellulose, the diameter is about submicron to several tens of nanometers. It is possible to obtain porous ceramics having the above pores and having pores penetrating the inside of the ceramic block.

The carbon fiber is a fiber composed of 90% or more of carbon by mass ratio, and is a fiber made by carbonizing polyacrylonitrile fiber or pitch fiber as a raw material at a high temperature. Carbon fiber is characterized by a low heat shrinkage rate, and when a material containing carbon fiber or carbon fiber crushed material is used as a combustion vaporization fine material. Since expansion and contraction of the combustion vaporized micromaterial in the firing step are unlikely to occur, cracks and cracks in the fired body are suppressed, and pores corresponding to the size of the carbon fiber or the carbon fiber crushed material are easily formed, which is preferable.

Cellulose is the main component of plant fiber and is a water-insoluble polysaccharide. As the combustion vaporization material containing cellulose, it is particularly preferable to use a material containing cellulose nanofibers. Cellulose nanofibers are fine cellulose fibers obtained by defibrating pulp (pulp fiber), which is a plant raw material, and generally contain cellulose fine fibers having a fiber width of nano size (1 nm or more and 1000 nm or less). Refers to fiber.

The water retention of the cellulose nanofibers is preferably, for example, 250% or more and 500% or less. The water retention rate (%) of the cellulose nanofibers is as follows: JAPAN TAPPI No. Measured according to 26. Cellulose nanofibers preferably have only one peak in the pseudo-particle size distribution curve measured by laser diffraction in an aqueous dispersion. The particle size (mode) of the cellulose nanofibers having this peak is preferably, for example, 5 μm or more and 50 μm or less. The "pseudo particle size distribution curve" means a curve showing a volume-based particle size distribution measured by using a particle size distribution measuring device.

Since cellulose is derived from plants, the use of cellulose nanofibers as a combustion vaporization material leads to a low-carbon society compared to the use of chemically synthesized materials such as polyvinyl alcohol and ammonium polyacrylate. It has the advantage of being able to contribute. It also has the advantage of being an environmentally friendly material because it does not emit harmful substances such as nitrogen oxides even when it is vaporized by combustion. Further, cellulose is characterized by having a low heat shrinkage rate like carbon fiber, and is also excellent in that expansion and shrinkage of the combustion vaporized fine material in the firing step are unlikely to occur like carbon fiber.
(Ceramic raw material)

The "ceramic raw material" is not particularly limited, but is, for example, alumina, aluminum silicate, cordierite, silica, zirconia, silicon carbide, silicon nitride, mullite, magnesia, and nitride, which are known as porous ceramic materials. Examples include, but are not limited to, aluminum, boron nitride, calcium phosphate, and the like. These raw materials can be used alone, but can also be used by mixing two or more ceramic raw materials.

As the raw material for ceramics, it is preferable to use calcium phosphate such as β-tricalcium phosphate or hydroxyapatite. Porous ceramic materials such as β-tricalcium phosphate and hydroxyapatite are used as bone filling materials and artificial bone implants as granules and molded bodies, but cells, proteins, drugs, etc. should be immobilized before use. Attempts have been made to promote replacement with autologous bone and improve bioabsorbability of substitute bone. It is generally said that cells are micron-sized, proteins are submicron-sized, and drugs are easily immobilized in nano-sized pores. According to the present invention, pore size, pore volume, pore density, and pore penetration are suitable for the purpose. This is because it becomes possible to obtain porous ceramics having a controlled degree and to immobilize proteins and the like.

An example is shown below. In the examples, β-tricalcium phosphate, alumina, or hydroxyapatite was used as a raw material for ceramics. In the examples, cellulose was used as the combustion vaporization material. As a premise of implementation, β-tricalcium phosphate and cellulose were prepared as follows.
(1) β-Tricalcium Phosphate (Preparation of β-Tricalcium Phosphate)

As raw materials for β-tricalcium phosphate, 301.78 g of calcium carbonate and 266.79 g of ammonium dihydrogen phosphate were prepared, and 2 liters of ethanol was used as a solvent for crushing and mixing with a ball mill for 48 hours. Ethanol was separated from the liquid mixture using a filtration device and / and an evaporator to obtain a slurry. The slurry was divided into two alumina sheaths and calcined A was performed to obtain a calcined body A. The conditions for calcination were a heating rate of 3 ° C./min, a firing temperature of 900 ° C., a holding time of 12 hours, and a temperature lowering rate of 3 ° C./min to room temperature under the conditions of an atmospheric atmosphere. The crystal phase of the obtained calcination A was 95% or more having a β-tricalcium phosphate structure, but in order to more reliably form the crystal phase into a β-tricalcium phosphate structure, two more times. Temporary sintering was performed. Specifically, the calcined body A was pulverized with a ball mill for 4 hours, placed in an alumina sheath, and calcined B was performed under the same conditions as the calcined A to obtain a calcined body B. The temporary fired body B, which had returned to room temperature, was temporarily sintered C again under the same conditions as those of the temporary sintered bodies A and B to obtain a temporary fired body C.

A powder of β-tricalcium phosphate having an average particle diameter of about 3 μm, which was obtained by pulverizing the temporarily fired body C with a ball mill or mortar and then sieving, was used as a ceramic raw material.
(Preparation of β-tricalcium phosphate in which silicon, sodium and magnesium are dissolved)

As a raw material for ceramics, β-tricalcium phosphate in which silicon, sodium and magnasium are dissolved can also be used. Sodium carbonate, magnesium oxide, and silicon dioxide are added to the above-mentioned starting material of β-tricalcium phosphate to prepare a powder of β-tricalcium phosphate in which 2.0 mol% of silicic acid is solid-dissolved in the same manner. The resulting powder was used as a raw material for ceramics. Specifically, 464.34 g of calcium carbonate, 427.40 g of ammonium dihydrogen phosphate, 3.4722 g of sodium carbonate, 18.8463 g of magnesium oxide, and 3.9332 g of silicon dioxide were used as starting materials.
(2) Hydroxyapatite

As hydroxyapatite, high-purity calcium phosphate of Taihei Kagaku Sangyo Co., Ltd. with an average particle size of 15 to 20 μm, spherical HAP (3Ca ₃ (PO ₄ ) ₂ · Ca (OH) ₂ ) was used.
(3) Alumina

As the alumina, the easily sinterable alumina AL-45-A manufactured by Showa Denko KK, which has a central particle diameter of 0.79 μm, was used.
(Preparation of cellulose)

As the cellulose, a cellulose nanofiber aqueous solution having a particle size (mode) of 21 μm, a water retention degree of 389%, and a concentration of 1.7 wt% was used. The cellulose nanofiber aqueous solution used contains cellulose fine fibers having a diameter of several tens of nm. However, the water retention level (%) of cellulose is determined by JAPAN TAPPI No. Measured according to 26. The volume-based particle size distribution measured using a particle size distribution measuring device was measured, and the most frequent value of the obtained pseudo particle size distribution curve was taken as the particle size.
(Evaluation method for porous ceramics)

The evaluation method of the manufactured porous ceramics will be described first. The pore distribution was measured with a mercury porosimeter and the microstructure was observed with a scanning electron microscope (SEM). The open porosity and the closed porosity were calculated from the volume, the dry mass, the water absorption mass and the true specific gravity (literature values). The volume was calculated by measuring the length and diameter of the obtained sintered body. The water absorption mass was measured by immersing the test piece in boiling water for 2 hours, allowing it to cool in water, and then measuring the mass.

<Experiment 1>
(Preparation step)
50 g of an aqueous solution of cellulose nanofibers and 45 g of β-tricalcium phosphate in which 2 mol% of silicic acid was dissolved were prepared.
(Kneading step)
The mixture was stirred with a stirrer for 3 minutes, 20 g of ion-exchanged water was further added, kneaded with a stirrer for 3 minutes, and then transferred to a Teflon (registered trademark) container. The state after kneading was paste-like, and water did not separate to the surface layer. It was dried at 65 ° C. for 1 to 2 days to obtain an intermediate. The dried intermediate had a certain shape and strength, and did not collapse even when cut out with a diamond cutter. It was also possible to make holes with a drill. The dried intermediate taken out of the Teflon (registered trademark) container was cut with a diamond cutter to prepare a substantially cube of about 10 mm square.
(Baking step)
The molded body was fired to produce porous ceramics. The firing was carried out under the conditions of a temperature rising rate of 3 ° C./min, a firing temperature of 1130 ° C., a holding time of 24 hours, a temperature lowering rate of 3 ° C./min to room temperature, and an atmospheric atmosphere.

FIG. 4 is a diagram showing the pore distribution, physical characteristic values, and fine structure of the obtained porous ceramics. The obtained porous ceramics was a dense body having a certain strength, the mode pore diameter was 2.79 μm, and pores were also observed in the vicinity of 90 to 110 nm. In addition, it was confirmed from the SEM photograph showing the fine structure that it was porous and that it was sintered.

<Experiment 2>
(Preparation step)
As in Experiment 1, 50 g of an aqueous solution of cellulose nanofibers and 45 g of β-tricalcium phosphate in which 2 mol% of silicic acid was dissolved were prepared.
(Kneading step)
The dried intermediate obtained in the kneading step of Experiment 1 was pulverized in an alumina mortar, and relatively large particles were removed using a sieve covered with a nylon mesh fiber to obtain an intermediate derivative. Obtained. The intermediate derivative was uniaxially pressure-molded at 32 MPa for 1 minute using a mold having a diameter of 20 mm to prepare a molded product.
(Baking step)
The obtained molded body was fired under the same conditions as in Experiment 1 to produce porous ceramics.

FIG. 5 is a diagram showing the pore distribution, physical characteristic values, and fine structure of the obtained porous ceramics. The obtained porous ceramics was a dense body having a certain strength, the mode pore diameter was 1.72 μm, and pores were also observed at 30 to 70 nm. In addition, it was confirmed from the SEM photograph showing the fine structure that it was porous and that it was sintered.

<Experiment 3>
(Preparation step)
As in Experiment 1, 50 g of an aqueous solution of cellulose nanofibers and 45 g of β-tricalcium phosphate in which 2 mol% of silicic acid was dissolved were prepared.
(Kneading step)
A molded body was prepared in the same manner as in Experiment 2 except that the uniaxial pressure molding was pressed at 98 MPa for 1 minute.
(Baking step)
The obtained molded body was fired under the same conditions as in Experiment 1 to produce porous ceramics.

FIG. 6 is a diagram showing the pore distribution, physical characteristic values, and fine structure of the obtained porous ceramics. The obtained porous ceramics was a dense body having a certain strength, the mode pore diameter was 1.03 μm, and pores were also observed at 20 to 60 nm. In addition, it was confirmed from the SEM photograph showing the fine structure that it was porous and that it was sintered.
<Experiment 4>
(Preparation step)
50 g of an aqueous solution of cellulose nanofibers and 45 g of hydroxyapatite were prepared.
(Kneading step)
The mixture was stirred with a stirrer for 3 minutes, 20 g of ion-exchanged water was further added, kneaded with a stirrer for 3 minutes, and then transferred to a Teflon (registered trademark) container. The state after kneading was paste-like, and water did not separate to the surface layer. It was dried at 65 ° C. for 1 to 2 days to obtain an intermediate. The dried intermediate had a certain shape and strength, and did not collapse even when cut out with a diamond cutter. It was also possible to make holes with a drill.
The obtained dried intermediate was pulverized in an alumina mortar, and relatively large particles were removed using a sieve covered with a nylon mesh fiber to obtain an intermediate derivative. The intermediate derivative was uniaxially pressure-molded at 98 MPa for 1 minute using a mold having a diameter of 20 mm to prepare a molded product.
(Baking step)
The obtained molded body was fired under the same conditions as in Experiment 1 to produce porous ceramics.

FIG. 7 is a diagram showing the pore distribution, physical characteristic values, and fine structure of the obtained porous ceramics. The obtained porous ceramics was a dense body having a certain strength, the mode pore diameter was 0.15 μm, and pores were also observed at 40 to 90 nm. In addition, it was confirmed from the SEM photograph showing the fine structure that it was porous and that it was sintered.
<Experiment 5>
(Preparation step)
50 g of an aqueous solution of cellulose nanofiber and 45 g of alumina were prepared.
(Kneading step)
The mixture was stirred with a stirrer for 3 minutes, 20 g of ion-exchanged water was further added, kneaded with a stirrer for 3 minutes, and then transferred to a Teflon (registered trademark) container. The state after kneading was paste-like, and water did not separate to the surface layer. It was dried at 65 ° C. for 1 to 2 days to obtain an intermediate. The dried intermediate had a certain shape and strength, and did not collapse even when cut out with a diamond cutter. It was also possible to make holes with a drill. The dried intermediate taken out of the Teflon (registered trademark) container was cut with a diamond cutter to prepare a substantially cube of about 10 mm square.
(Baking step)
The molded body was fired to produce porous ceramics. The firing was carried out under the conditions of a heating rate of 3 ° C./min, a firing temperature of 1600 ° C., a holding time of 24 hours, a temperature lowering rate of 3 ° C./min to room temperature, and an atmospheric atmosphere.

FIG. 8 is a diagram showing the pore distribution, physical property values, and fine structure of the obtained porous ceramics. The obtained porous ceramics was a dense body having a certain strength, the mode pore diameter was 0.42 μm, and pores were also observed at 90 to 200 nm. In addition, it was confirmed from the SEM photograph showing the fine structure that it was porous and that it was sintered.
<Effect>

As shown in FIGS. 4 to 8, the obtained porous ceramics had nano-sized pores in addition to the peak of the most frequent pore diameter.

Further, in the production of porous ceramics, a dispersant (dispersant), a binder, and a lubricant having a solid content of about 5 to 20 are often used for the ceramic raw material 100, but in the present embodiment, the ceramics are used. It is also excellent in that it exhibits the effects of the dispersant and the binder at a low concentration of about 2 in terms of solid content with respect to the raw material 100.
<Embodiment 2>

This embodiment is a porous ceramic, and its characteristic feature is that it has pores that can be discharged to the outside even when it is filled with the combustion vaporization material used in the production, and the pores are fine with a submicron diameter. It is at a point containing a hole. In this ceramic, the high pressure side and the low pressure side are formed by using the ceramic as a partition wall, and the combustion vaporization material is infiltrated by using the pressure difference. Then, by placing the infiltrated ceramics in the combustion atmosphere of the combustion vaporizing material, all the combustion vaporizing material infiltrated inside is removed. This makes it possible to support a combustion vaporizing material having a large surface area per unit volume. The ceramics can be manufactured by the embodiments already described. For example, it can be manufactured by a process such as Experiment 1 to Experiment 3.

That is, the porous ceramics of the present embodiment have pores in which the combustion vaporizing material filled by firing can be discharged to the outside even when the pores are filled with the combustion vaporizing material, and the pores have a submicron diameter. Contains pores. For example, carbon and cellulose nanofibers correspond to the combustion vaporization material.

Claims (3)

A preparatory step for preparing a fibrous combustion vaporizing material having a maximum diameter of submicron and a ceramic raw material (excluding alumina and a combination of alumina and other raw materials).
A kneading step in which a liquid or slurry obtained by kneading the prepared combustion vaporization material and ceramic raw material (excluding alumina and the combined use of alumina and other raw materials) is dried to obtain a block-shaped intermediate. ,
A crushing step in which the block-shaped intermediate is crushed and kneaded again is repeated.
A firing step for calcining an intermediate or / and an intermediate derivative to burn vaporize the combustion vaporized material to obtain a ceramic having a plurality of pores having openings on the surface penetrating the inside.
A method for manufacturing porous ceramics composed of. The method for producing a porous ceramic according to claim 1, further comprising a chemical impregnation step of impregnating the porous ceramic obtained in the firing step with a chemical. A fibrous combustion vaporized material having a maximum diameter of submicron is uniformly dispersed in a ceramic raw material (excluding alumina and a combination of alumina and other raw materials), and has an opening on the surface through the inside. Ceramics consisting of a blocking step for blocking an intermediate for producing a porous ceramic having a plurality of pores, a drying step for drying the block, and a crushing step for crushing the dried block to obtain a ground powder. A method for producing an intermediate derivative in which a fibrous combustion vaporizing material having a maximum diameter of submicron is more uniformly dispersed in a raw material (excluding alumina and a combination of alumina and other raw materials).

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