Ceramic porous body and method for producing the same

Abstract

To provide a ceramic porous body having a high porosity while exhibiting a small linear shrinkage ratio during firing and a small linear shrinkage ratio caused by heating.SOLUTION: A ceramic porous body is formed of ceramics and contains a large number of spherical pores partitioned by partition walls. The pores include: communicating pores in which through-holes are formed in the partition walls; and independent pores in which no through-holes are formed in the partition walls. The communicating pores adjacent to each other are connected through the through-holes to form a continuous cell structure. The independent pores have a median diameter (D50) of 0.1 to 1.3 mm, the proportion of the independent pores on a cut surface is 10 to 30 area%, and the porosity is 50 to 99%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a ceramic porous body and a method for producing the same. [Background technology]

[0002] Various porous ceramic bodies usable under high-temperature conditions and methods for manufacturing them have been proposed. For example, a method has been proposed for manufacturing a porous ceramic body by freezing a slurry prepared by dispersing ceramic raw material powder in water, causing ice to grow in one direction, and then freeze-drying the slurry to sublimate the ice (Patent Document 1). Furthermore, a method has been proposed for manufacturing a porous ceramic body with high handling strength and formed with interconnected pores by gelling a slurry of ceramic raw material powder to which a gelling agent has been added, followed by freezing, drying, and firing (Patent Document 2).

[0003] In addition, a method has been disclosed for producing a ceramic porous body with high thermal insulation properties, in which a partition structure is formed inside the body and the body has partially blocked interconnecting pores, using as a raw material a slurry of ceramic raw material powder to which a gelling agent and a water-soluble polymer have been added (Patent Document 3).

[0004] However, the porous ceramic bodies produced by the methods proposed in Patent Documents 1 and 2 are structurally characterized by the formation of macroporous interconnected pores, which allow heat and gas to easily pass through, making them difficult to use as thermal insulators, a type of porous ceramic body that can be used under high-temperature conditions. On the other hand, the porous ceramic body produced by the method proposed in Patent Document 3 has interconnected pores that are partially blocked by a partition structure formed inside, making it promising for use as a thermal insulator. However, as mentioned above, the porous ceramic bodies proposed in Patent Documents 1 to 3 have issues as structural materials, such as significant differences in mechanical properties depending on the direction, and the tendency for coarse ice crystals that cause coarse defects to form during freezing, making it difficult to produce large sizes.

[0005] In contrast, a ceramic porous body has been proposed that is manufactured using a slurry to which bubbles prepared using surfactants or the like have been added. This porous body has little difference in physical properties depending on the direction, and the presence of bubbles can suppress the formation of coarse ice crystals during freezing, making it strong enough to be used as a structural material (Patent Document 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-192280 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-201636 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-195437 [Patent Document 4] Japanese Patent Application Laid-Open No. 2018-140905 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the ceramic porous body proposed in Patent Document 4 is prone to linear shrinkage during firing and also tends to linear shrink when exposed to high temperature conditions. That is, while the conventional ceramic porous body proposed in Patent Document 4 has a high porosity, the linear shrinkage during firing and the linear shrinkage caused by heating are relatively large, leaving room for further improvement.

[0008] The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide a ceramic porous body that has a high porosity but has a small linear shrinkage during firing and a small linear shrinkage caused by heating. Another object of the present invention is to provide a manufacturing method that can easily manufacture this ceramic porous body. [Means for solving the problem]

[0009] That is, according to the present invention, the following ceramic porous body is provided. [1] A ceramic material containing a large number of spherical pores separated by partition walls, the pores including interconnected pores in which through-holes are formed in the partition walls and isolated pores in which no through-holes are substantially formed in the partition walls, the interconnected pores communicating with each other via the through-holes form an open-cell structure, and the median diameter (D 50 ) is 0.1 to 1.3 mm, the proportion of the closed pores in a cut surface is 10 to 30 area %, and the porosity is 50 to 99%. [2] The ceramic porous body according to [1], wherein the ceramic is at least one selected from the group consisting of mullite, alumina, zirconia, silica, silicon carbide, silicon nitride, boron nitride, cordierite, and carbon. [3] The ceramic porous body according to [1] or [2], wherein the residual linear shrinkage at a temperature that is 80% of the melting point of the ceramic is 1% or less.

[0010] The present invention also provides the following method for producing a ceramic porous body. [4] A ceramic slurry containing ceramic raw material powder, a gelling agent, and water, and foams prepared using surfactants and water, and their median diameter (D 50 and ceramic hollow particles having a median diameter (D ) of 0.1 to 1.5 mm, and gelling the resulting raw material slurry to obtain a gel body; freezing the gel body to obtain a frozen body; and removing ice from the frozen body to obtain a dried body, which is then fired to obtain a ceramic hollow particle having a plurality of spherical pores defined by partition walls, the pores including interconnected pores having through-holes formed in the partition walls and closed pores having substantially no through-holes formed in the partition walls, and adjacent interconnected pores communicate with each other via the through-holes to form an open-cell structure, and the closed pores have a median diameter (D ) of 0.1 to 1.5 mm. 50 and obtaining a porous ceramic body having a diameter of 0.3 to 1.3 mm, a proportion of the closed pores in a cut surface of 10 to 30 area %, and a porosity of 50 to 99%. [5] The method for producing a ceramic porous body according to [4], wherein the content of the ceramic hollow particles in the raw material slurry is 10 to 30 parts by volume per 100 parts by volume of the total of components other than the ceramic hollow particles. [6] The method for producing a ceramic porous body according to [4] or [5], wherein the ceramic is at least one selected from the group consisting of mullite, alumina, zirconia, silica, silicon carbide, silicon nitride, boron nitride, cordierite, and carbon. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a ceramic porous body that has high porosity but small linear shrinkage during firing and linear shrinkage caused by heating, and also to provide a manufacturing method that can easily manufacture this ceramic porous body. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an SEM photograph of a cross section of the ceramic porous body obtained in Example 1. [Figure 2] 1 is an SEM photograph of a cut surface of a test piece for observation formed by embedding a cross section of the ceramic porous body obtained in Example 1 in resin. [Figure 3] 1 is an SEM photograph of a cross section of the ceramic porous body obtained in Comparative Example 1. [Figure 4] 1 is an SEM photograph of a cut surface of a test piece for observation formed by embedding a cross section of the ceramic porous body obtained in Comparative Example 1 in resin. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Porous ceramics> Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. One embodiment of the ceramic porous body of the present invention is a porous body formed of a ceramic such as mullite, alumina, zirconia, silica, silicon carbide, silicon nitride, boron nitride, cordierite, or carbon, containing a large number of spherical pores separated by partition walls. The large number of pores include interconnected pores with through-holes formed in the partition walls and closed pores with substantially no through-holes formed in the partition walls, and adjacent interconnected pores communicate with each other via the through-holes to form an open-cell structure. The ceramic porous body of this embodiment, which has such a unique open-pore structure, has substantially no directional dependency.

[0014] The median diameter of the isolated pores (D 50 ) is 0.1 to 1.3 mm, preferably 0.3 to 1.2 mm, and more preferably 0.8 to 1.2 mm. By including closed pores with such a diameter, it is possible to reduce the linear shrinkage during firing and the linear shrinkage caused by heating, while maintaining a high porosity. The median diameter (D 50 ) can be measured and calculated by image analysis of a cross-sectional specimen prepared by filling any cut surface of a porous ceramic body with resin and polishing it using a scanning electron microscope (SEM).

[0015] The proportion of closed pores in the cut surface of the ceramic porous body is 10 to 30 area %, preferably 15 to 30 area %, and more preferably 20 to 30 area %. By keeping the proportion of closed pores within the above range, it is possible to reduce the linear shrinkage during firing and the linear shrinkage caused by heating. The proportion of closed pores in the cut surface of the ceramic porous body can be measured and calculated by observing the cut surface of the above-mentioned test piece for cross-section observation with a scanning electron microscope (SEM) and analyzing the images.

[0016] The porosity of the ceramic porous body is 50 to 99%, preferably 60 to 95%, and more preferably 70 to 90%. The porosity of the ceramic porous body can be calculated by subtracting the relative density calculated by calculating the density from the dimensions and mass of the ceramic porous body and dividing it by the density of the ceramic from 100.

[0017] The ceramic porous body of this embodiment has the unique pore structure described above, and therefore has high porosity (lightweight) and high air permeability, as well as a small linear shrinkage caused by heating and excellent thermal shock resistance, making it usable under high-temperature conditions. More specifically, the residual linear shrinkage of the ceramic porous body of this embodiment at a temperature that is 80% of the melting point of the ceramic is preferably 1% or less, and more preferably 0.5% or less. There are no particular restrictions on the lower limit of the residual linear shrinkage, and it is generally 0.1% or more. Note that the "temperature that is 80% of the melting point of the ceramic" is, for example, approximately 1,660°C when the ceramic is alumina (melting point: approximately 2,070°C).

[0018] The ceramic porous body of this embodiment contains many spherical pores, and therefore the difference in physical properties depending on the orientation (direction) is small. Therefore, the ceramic porous body of this embodiment is suitable as a structural material for various filters, heat insulating materials, automobile filters that require excellent thermal shock resistance, and kiln packing tools (setters, sheaths, etc.) used in firing electronic components, etc.

[0019] <Method for manufacturing porous ceramics> Next, a method for producing a ceramic porous body of the present invention will be described. One embodiment of the method for producing a ceramic porous body of the present invention is suitable for producing the above-mentioned ceramic porous body. That is, the method for producing a ceramic porous body of this embodiment includes the steps of: gelling the raw material slurry obtained by mixing a ceramic slurry containing a ceramic raw material powder, a gelling agent, and water, foam prepared using a surfactant and water, and ceramic hollow particles to obtain a gel; freezing the gel to obtain a frozen body; and removing ice from the frozen body and firing the resulting dried body to obtain the above-mentioned ceramic porous body. Note that the technical details of each method can basically be those described in JP 2008-201636 A (Patent Document 2) and JP 2018-140905 A (Patent Document 4).

[0020] In the gelation process, first, a ceramic slurry containing ceramic raw material powder, a gelling agent, and water is prepared. The amount of raw material powder in the ceramic slurry is typically 1 to 30% by volume. The raw material powder may be any ceramic powder (including carbon powder) that disperses in water. One of the features of the manufacturing method of this embodiment is that it is not dependent on the type of raw material. Therefore, the type of ceramic that constitutes the raw material powder can be appropriately selected taking into consideration factors such as cost and the strength of the final product. Specific examples of ceramics that constitute the raw material powder include mullite, alumina, zirconia, silica, silicon carbide, silicon nitride, boron nitride, cordierite, and carbon. These ceramics can be used alone or in combination. A trace amount of a sintering aid can be added to the ceramic slurry.

[0021] One of the features of the manufacturing method of this embodiment is that it can produce a highly porosity ceramic porous body having a unique pore structure regardless of the type of starting material. Therefore, the shape and size of the raw material powder are not particularly limited. However, the particle size (diameter) of the raw material powder is preferably 0.01 to 100 μm, and more preferably 0.01 to 5 μm. By using raw material powder with a particle size within this range, the raw material powder can be easily crushed and more uniformly dispersed in the ceramic slurry or raw material slurry being prepared. However, if the particle size of the raw material powder is too large, it will be prone to settling, which may make it difficult to prepare a homogeneous gel body.

[0022] The ceramic slurry may contain a dispersant to disperse the ceramic powder. Examples of dispersants include polyethyleneimine, polyvinylamine, polyallylamine, ammonium polyacrylate, ammonium polycarboxylate, nonionic surfactants, cationic surfactants, and polyhydric alcohol esters. The content of the dispersant in the ceramic slurry is usually about 0.1 to 2 mass%.

[0023] The gelling agent may be a water-soluble polymer compound capable of preparing a gel, such as N-alkylacrylamide polymers, N-isopropylacrylamide polymers, sulfomethylated acrylamide polymers, N-dimethylaminopropylmethacrylamide polymers, polyalkylacrylamide polymers, alginic acid, polyethyleneimine, starch, carboxymethylcellulose, gelatin, hydroxymethylcellulose, sodium polyacrylate, polyvinyl alcohol, polyethylene glycol, agar, and polyethylene oxide.

[0024] In the gelation step, a foam (mousse-like foam) is prepared using a surfactant and water. The method for preparing the foam is not particularly limited. For example, an aqueous solution containing a surfactant (foam raw material) may be foamed using an ultra-fine bubble generator or the like. When preparing the foam, it is preferable to use a foam raw material (aqueous solution) containing 5 to 10 mass % of a surfactant.

[0025] Examples of surfactants include fatty acid alkali salts, amine compounds, alkylbenzene sulfonates, higher alcohol sulfates, polyoxyethylene alkyl ether sulfates, sulfofatty acid esters, olefin sulfonates, alkyl phosphate esters, alkyltrimethylammonium salts, amine salts, alkylamino fatty acid salts, polyoxyethylene alkyl ethers, alkyl glycosides, sorbitan fatty acid esters, and fatty acid alkanolamides. These surfactants can be used alone or in combination of two or more.

[0026] In the gelation process, the prepared ceramic slurry, bubbles, and ceramic hollow particles (hereinafter simply referred to as "hollow particles") are mixed to obtain a raw slurry. The diameter of the bubbles (bubble diameter) in the obtained raw slurry is preferably 10 to 150 μm, and more preferably 20 to 100 μm. The bubble diameter of the bubbles can be measured by the following method. First, a portion of the bubble-containing raw slurry or a portion of the prepared bubbles is sampled, and an enlarged image is obtained using a microscope. Next, as in the case of measuring the pore diameter of a ceramic porous body, the obtained enlarged image is subjected to image analysis, and the bubble contours are extracted and converted into a histogram for measurement.

[0027] The median diameter of the hollow particles (D 50 ) is 0.1 to 1.5 mm, preferably 0.3 to 1.3 mm, and more preferably 1.0 to 1.3 mm. By using hollow particles of such a particle size, it is possible to reduce the linear shrinkage rate during firing, and to produce a ceramic porous body containing the above-mentioned preferable closed pores while suppressing the occurrence of warping and cracks. The median diameter (D50 If the median diameter (D ) of the hollow particles is less than 0.1 mm, it becomes difficult to sufficiently reduce the linear shrinkage at the temperatures during firing and use. 50 If the thickness exceeds 1.5 mm, hollow particles tend to segregate in the lower part of the resulting ceramic porous body, and warping and cracks tend to occur.

[0028] The ceramics constituting the hollow particles may be the same as those constituting the ceramic porous body to be produced, i.e., at least one selected from the group consisting of mullite, alumina, zirconia, silica, silicon carbide, silicon nitride, boron nitride, cordierite, and carbon.

[0029] The content of hollow particles in the raw slurry is preferably 10 to 30 parts by volume, and more preferably 15 to 30 parts by volume, per 100 parts by volume of the total of components other than the ceramic hollow particles. If the content of hollow particles in the raw slurry is less than 10 parts by volume, the linear shrinkage coefficient at the temperatures during firing and use may not be sufficiently reduced. On the other hand, if the content of hollow particles in the raw slurry is more than 30 parts by volume, the hollow particles may be more likely to segregate and warping or cracking may occur. Note that "components other than ceramic hollow particles" also includes "bubbles." Therefore, the volume of bubbles is also included in "100 parts by volume of the total of components other than ceramic hollow particles."

[0030] To achieve a porosity of 50 to 99% for the final ceramic porous body, it is preferable to set the content of each component in the raw material slurry within the following ranges. That is, the content of raw material powder in the raw material slurry is preferably 50% by volume or less. Furthermore, the content of water in the raw material slurry is preferably 48.9% by volume or less. Furthermore, the content of gelling agent in the raw material slurry is preferably 1 to 5% by volume. If the content of gelling agent in the raw material slurry is too low, gelation may not proceed easily. On the other hand, if the amount of gelling agent in the raw material slurry is too high, the gel strength of the resulting gel body tends to be excessively high, and water separation properties during freezing tend to be reduced.

[0031] The content of bubbles in the raw material slurry is preferably 30 to 90% by volume based on the total volume of the raw material slurry. By keeping the content of bubbles in the raw material slurry within this range, mechanical properties are maintained, and a ceramic porous body that is more useful as a structural material can be produced. If the content of bubbles in the raw material slurry is too high, handling may become difficult, and the high-temperature properties of the resulting ceramic porous body may be slightly reduced due to the influence of the surfactant.

[0032] The raw material slurry is poured into a mold of the desired shape and cooled as necessary to gel the raw material slurry and obtain a gel body. The resulting gel body is solidified while retaining water. Furthermore, the raw material powder made of ceramic is fixed in the gel body.

[0033] In the freezing step, the gel obtained in the gelling step is frozen to obtain a frozen body. Specifically, a frozen body in which ice crystals are formed within the gel body can be obtained by cooling a portion or the entire surface of the mold. The freezing method can be any known cooling method, such as a conventional freezer or freezing tank. The freezing temperature used to produce the frozen body may be any temperature at which the water retained in the gelling agent freezes. However, temperatures around -10°C accelerate the growth of ice crystals, making them prone to coarsening, and tend to make it difficult to maintain the structure containing numerous pores fixed in the gelling step (the same phenomenon that occurs when ice coarsens and destroys the tissue if food is not flash-frozen). For this reason, the freezing temperature is preferably -20°C or below, and more preferably -30 to -50°C.

[0034] In the firing process, the dried body obtained by removing the ice from the frozen body is fired. Firing the dried body allows for the production of a porous ceramic body with a specific pore structure. When removing the ice from the frozen body, it is preferable to remove only the ice so as not to destroy the structure of the raw material powder and ice crystals that make up the frozen body. In other words, it is preferable to adopt an ice removal method (drying method) that minimizes dimensional change and the risk of sample destruction. It is preferable to adopt the freeze-drying method as a drying method that minimizes dimensional change and the risk of sample destruction. The freeze-drying method is a method in which the ice in the frozen body is directly sublimated under reduced pressure and only the ice is removed. This method is preferable because the ice sublimes from the surface of the frozen body, minimizing dimensional change.

[0035] The firing temperature of the dried body can be set depending on the type of ceramics constituting the raw material powder used. Furthermore, the firing temperature can be set from the viewpoint of ensuring the strength of the resulting ceramic porous body. For example, firing is preferably performed at 1,500 to 1,700°C for mullite, 1,100 to 1,600°C for alumina, 1,200 to 1,600°C for zirconia, 1,000 to 1,300°C for silica, 1,500 to 2,300°C for silicon carbide and silicon nitride, 1,400 to 2,500°C for boron nitride, 1,300 to 1,500°C for cordierite, and 1,000 to 2,500°C for carbon. [Example]

[0036] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are by mass unless otherwise specified.

[0037] <Production of porous ceramics> Example 1 A ceramic slurry was prepared by mixing 6.4 parts by volume of alumina (trade name "AES-12", manufactured by Sumitomo Chemical Co., Ltd.), 27.8 parts by volume of distilled water, and 1.0 part by volume of a gelling agent (gelatin, manufactured by Wako Pure Chemical Industries, Ltd.). Meanwhile, a foam raw material was prepared by mixing 0.2 parts by volume of a surfactant (main component: trade name "Amilite GCK-11", manufactured by Ajinomoto Healthy Supply Co., Ltd.) and 4.6 parts by volume of distilled water. Gas was then blown into the foam raw material to prepare foam with an average diameter of 80 μm. The foam (60 parts by volume) was added to the ceramic slurry, and the median diameter (D 5024.9 parts by volume of 1.3 mm hollow alumina particles (hollow particles produced by electrofusion, trade name "Hollow Fused Alumina BL", manufactured by Pacific Random Corporation) were further added and mixed to prepare a raw material slurry. The prepared raw material slurry was cast into a mold and placed in a refrigerator to gel. The mold was placed on a shelf (cooling plate) in the freezing chamber and cooled to -40°C for 1 hour to obtain a frozen body. The resulting frozen body was removed from the mold and dried for 12 hours using a freeze-drying device to obtain a dried body, a rectangular parallelepiped measuring 100 × 100 × 20 mm. The dried body was placed in a firing furnace and fired at 1,600°C for 2 hours to obtain a porous ceramic body. Arbitrary cut surfaces of the resulting porous ceramic body were filled with resin and then polished to obtain test specimens for cross-sectional observation. An SEM photograph of the cross section of the resulting porous ceramic body is shown in Figure 1. Figure 2 shows an SEM photograph of the cross section of a test specimen for observation formed by filling the cross section of the porous ceramic body with resin. As shown in Figure 1, it can be seen that there are many nearly spherical pores separated by partition walls. It can also be seen that the pores include interconnected pores where through-holes are formed in the partition walls, and closed pores where no through-holes are formed in the partition walls. It can also be seen that adjacent interconnected pores communicate with each other via the through-holes, forming an open-cell structure.

[0038] (Examples 2 to 5, Comparative Example 2) The type of ceramics, the type of hollow particles, and the median diameter of the hollow particles (D 50 A ceramic porous body was produced in the same manner as in Example 1, except that the additives and amounts thereof were as shown in Table 1. In Table 1, the "mullite" used was a product called "KM-101" (manufactured by Kyoritsu Material Co., Ltd.). The ceramic porous body obtained in Comparative Example 2 had hollow particles segregated in the lower part, and had warpage and cracks.

[0039] (Comparative Example 1) A ceramic porous body was produced in the same manner as in Example 1, except that hollow particles were not used. An SEM photograph of the cross section of the obtained ceramic porous body is shown in Figure 3. Also, an SEM photograph of the cut surface of a test piece for observation formed by embedding the cross section of the ceramic porous body in resin is shown in Figure 4.

[0040] TIFF2025116918000001.tif81170

[0041] <Evaluation> (1) Porosity The density was calculated from the dimensions and mass of the ceramic porous body, and the relative density (%) was calculated by dividing it by the density of the ceramic. The porosity (%) was calculated as the value obtained by subtracting the relative density (%) from 100. The results are shown in Table 2.

[0042] (Firing linear shrinkage) The firing linear shrinkage was calculated from the dimensions of the dried body and the dimensions of the ceramic porous body. The results are shown in Table 2.

[0043] (Residual linear shrinkage) Of the obtained ceramic porous bodies, the porous bodies of Examples 1 to 4 and Comparative Example 1 were heated at 1,600°C (77% of the melting point), and the porous body of Example 5 was heated at 1,450°C (78% of the melting point) for 3 hours, and then allowed to cool. The residual linear shrinkage was calculated from the dimensions of the ceramic porous body before and after heating. The results are shown in Table 2.

[0044] (Median diameter and percentage of closed pores) The cross-section of the porous ceramic body was filled with resin and polished to prepare a specimen for cross-sectional observation. The median diameter of the isolated pores (D 50 The percentage of closed pores in the cut surface was calculated. The results are shown in Table 2.

[0045] TIFF2025116918000002.tif68170 [Industrial Applicability]

[0046] The ceramic porous body of the present invention is useful not only as a constituent material for various filters and as a heat insulating material, but also as a structural material for automobile filters that require excellent thermal shock resistance and kiln packing tools (setters, sheaths, etc.) used in firing electronic components, etc.

Claims

1. It is made of ceramics and contains many spherical pores separated by partition walls. the pores include connected pores in which a through-hole is formed in the partition wall, and isolated pores in which a through-hole is not substantially formed in the partition wall, adjacent communicating pores communicate with each other via through-holes to form an open-cell structure, The median diameter of the independent pores (D ５０ ) is 0.1 to 1.3 mm, The ratio of the closed pores in the cut surface is 10 to 30% by area, A ceramic porous body having a porosity of 50 to 99%.

2. 2. The ceramic porous body according to claim 1, wherein the ceramic is at least one selected from the group consisting of mullite, alumina, zirconia, silica, silicon carbide, silicon nitride, boron nitride, cordierite, and carbon.

3. 3. The ceramic porous body according to claim 1, wherein the residual linear shrinkage at a temperature that is 80% of the melting point of the ceramic is 1% or less.

4. A ceramic slurry containing ceramic raw material powder, a gelling agent, and water, a surfactant, and water were used to prepare bubbles, and the median diameter (D ５０ and a step of gelling the raw material slurry obtained by mixing the ceramic particles and the ceramic hollow particles having a size of 0.1 to 1.5 mm to obtain a gel body; a step of freezing the gel body to obtain a frozen body; A dried body obtained by removing ice from the frozen body is baked to contain a large number of spherical pores partitioned by partition walls, the pores including interconnected pores in which through-holes are formed in the partition walls and closed pores in which no through-holes are substantially formed in the partition walls, and adjacent interconnected pores communicate with each other via the through-holes to form an open-cell structure, and the median diameter (D ５０ ) is 0.1 to 1.3 mm, the proportion of the closed pores in the cut surface is 10 to 30 area %, and the porosity is 50 to 99%; A method for producing a ceramic porous body having the above structure.

5. 5. The method for producing a ceramic porous body according to claim 4, wherein the content of the ceramic hollow particles in the raw material slurry is 10 to 30 parts by volume per 100 parts by volume of the total of components other than the ceramic hollow particles.

6. 6. The method for producing a ceramic porous body according to claim 4, wherein the ceramic is at least one selected from the group consisting of mullite, alumina, zirconia, silica, silicon carbide, silicon nitride, boron nitride, cordierite, and carbon.

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