JP2001240480A - Porous ceramic structural body, its manufacturing method and fluid permeable member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a porous ceramic structural body and a fluid permeable member which are excellent in isotropic strength and fluid permeation characteristics. SOLUTION: This porous ceramic structural body 1 is obtained in such a way that between skeleton parts 2 of dense ceramics, pores 3 are made exist whose mean diameter is 0.01-10 mm, and 90% of pore diameters are included within the range of ±30% of the mean pore diameter, and adjacent pores 3, 3 are communicating through communicating pores 5, and the mean diameter of the communicating pores is >=1/4 of the mean diameter of the pores 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous ceramic structure in which a substance enters and exits through pores of a structure such as a fluid permeable member such as a filter or a catalyst carrier or a living body substitute member, and a method of manufacturing the same. .

[0002]

2. Description of the Related Art Conventionally, a porous ceramic structure has excellent stability and corrosion resistance at a high temperature, so that a heat-insulating material, a refractory, a fluid-permeable member such as a filter for fluid filtration, a catalyst carrier, and an artificial living body. The application as a member etc. is expected.

[0003] As a method for producing such a porous ceramic structure, for example, Japanese Patent Publication No. 63-63249 discloses a method in which a cylindrical tube such as a honeycomb is filled with a slurry containing a ceramic raw material to which a foaming agent generating carbon dioxide gas is added. It is described that an exhaust gas purifying structure in which a cylindrical pipe is filled with porous ceramics can be produced by foaming and firing the same.

In Japanese Patent Application Laid-Open No. 10-130002, a sol containing a metal, which is a ceramic raw material, is applied with pressure and extruded from a nozzle into a fibrous form, which is deposited on a sheet to form a three-dimensional network-like structure. Production is described.

Further, in Japanese Patent Application Laid-Open No. Hei 5-3094091, a synthetic resin foam such as urethane foam is immersed in a slurry containing a ceramic raw material powder to form a film on the foam surface, which is then hot-statically treated. Hydraulic press (H
It is described that a high-strength porous ceramic structure composed of a ceramic coating can be produced by burning out a synthetic resin foam by IP) baking.

[0006]

However, in the structure of Japanese Patent Publication No. 63-63249 in which a porous ceramic is filled in a cylindrical tube, the structure such as strength is anisotropic, so that the structure is only used for a simple shape. There is a problem that it cannot be used, and it is difficult to control the pore diameter of the structure, and it is not possible to optimize the mechanical strength and the high porosity of the structure. It is difficult to control the communication between them, and the fluid permeability of the fluid permeable member such as a filter or a catalyst carrier and the permeability with the bone formation property in the artificial biological member are reduced, and sufficient characteristics are obtained. There was a problem that can not be.

Further, in the porous body in which ceramic fibers are deposited as disclosed in Japanese Patent Application Laid-Open No. Hei 10-130002, the strength of the structure itself is weak due to the weak bonding force of the contact portion between the fibers, and the pore diameter is controlled. There was a problem that it was not possible.

Furthermore, in the porous structure using urethane foam disclosed in Japanese Patent Application Laid-Open No. 5-3094091, the mechanical strength is insufficient because the ceramic coating serving as a skeleton becomes a hollow body due to the burning out of the urethane foam. There was a problem that is.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide isotropic and high mechanical strength and porosity, and to enhance communication between pores to achieve high permeability. To manufacture a porous ceramic structure having the same.

[0010]

The present inventors have studied the skeletal structure and pore structure of the porous ceramic structure, and found that the spheroid for forming pores burned out in the slurry or sol for forming the skeleton by firing. After the body is added and poured into the mold, the spheres for forming pores are deformed so as to come into contact with each other at a predetermined ratio, and are baked to obtain a solid skeleton and a uniform size. It has been found that a porous ceramic structure having the above pores can be produced and the continuity between the pores can be enhanced.

That is, in the porous ceramic structure of the present invention, pores are present between the skeleton portions made of dense ceramics, the average pore diameter is 0.01 to 10 mm, and the diameter of the pores is the average pore diameter. The ratio is within ± 30% with respect to 90% or more, and the adjacent pores are communicated by the communication holes, and the average diameter of the communication holes is 1/4 or more of the average pore diameter. Is what you do.

The pores may be filled with a porous ceramic having a relative density of 60% or less, and the porous ceramic is selected from the group consisting of silicon nitride, alumina, aluminate, aluminum borate and mullite. It is preferable to contain needle-like or plate-like particles having an aspect ratio of 3 or more made of at least one type of ceramics.

Further, the method for producing a porous ceramic according to the present invention comprises the steps of: preparing a slurry or sol containing a ceramic raw material forming a skeleton; and forming a slurry or sol having an average diameter of 0.01 to 10 mm in the slurry or sol. And a step of adding a pore-forming sphere having a ratio of within ± 30% to the average diameter of 90% or more, and after pouring the slurry or sol to which the sphere is added into a molding die, The method is characterized by comprising a step of deforming the spherical body so that the spherical bodies come into surface contact with each other, and a step of firing the remaining part after removing the spherical body to form pores.

Preferably, the pores are filled with a porous ceramic having a relative density of 60% or less.
In particular, the spheres for forming pores may be granules containing a ceramic raw material forming a porous ceramic and an organic substance. Further, it is desirable that the granules contain starch and burn out when the pores are formed.

The porous ceramic structure can be suitably used as one member of a fluid permeable member.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view showing an example of a porous ceramic structure of the present invention. According to FIG. 1, the porous ceramic structure 1 has pores 3 irregularly communicating between skeleton parts 2 made of dense ceramics having a relative density of 90% or more, particularly 92% or more, and more preferably 95% or more.
However, the porosity is desirably 60% or more, particularly 65% or more, and more preferably 70% or more. According to FIG. 1, the pores 3 are filled with porous ceramics 4.

According to the present invention, the skeleton 2 is a three-dimensional mesh-like ceramic and is a solid body, and the skeleton 2 defines the pores 3 so that the structure 1 is isotropic. It can be applied to members of any shape, from simple to complex, and has no anisotropy in mechanical and transmission characteristics, greatly improving the reliability of structures such as transmission members. Is done.

According to the present invention, the pores 3 have an average pore diameter of 0.01 to 10 mm and a uniform pore diameter of 90% or more with respect to the average pore diameter within ± 30%. It is a major feature that the mechanical strength of the structure 1 can be increased without stress concentration on the specific pores 3 having a large pore diameter. Therefore, the porosity of the structure 1 can be increased. As a result, filter performance and catalyst performance when the structure 1 is used as a fluid permeable member such as a filter or a catalyst carrier are improved.

Further, according to the present invention, the adjacent pores 3, among the pores 3, are communicated with each other by the communication hole 5, and the average diameter of the communication hole 5 is one of the average pore diameter of the pore 3.
A major characteristic is that the ratio is / 4 or more, whereby the material permeation characteristics of the structure 1 that allows the material to enter and exit from the outside such as a fluid permeable member can be improved.

The porosity and pore diameter in the present invention are values obtained by image analysis of pores measured by a fracture surface SEM photograph. Further, the average diameter of the communication holes 5 is also obtained by image analysis of the pores measured by the SEM photograph of the fracture surface.

The pores 3 have porous ceramics 4 therein.
In order to control the pore diameter of the porous ceramics 4 and increase the strength of the structure 1, it is desirable to fill the porous ceramics 4 with the porous ceramics 4. In order to increase the transmittance of the member, it is desirably 60% or less, particularly preferably 40% or less.

The skeleton 2 and the pores 3 are filled.
The porous ceramics 4 to be used _TwoO_Three, ZrO_Two,
Acids such as light, cordierite, and aluminum titanate
Compound, Si_ThreeN_Four, AlN, nitrides such as TiN, SiC,
Carbides such as TiC, TiB_Two, AlB_Two, ZrB_TwoE
Oxides, oxynitrides such as SiAlON, AlON, TiC
At least one selected from the group of carbonitrides such as N
Sintered or unsintered ceramics as the main crystal is suitable
Applicable.

Among the above-mentioned porous ceramics, it is desirable to use mainly an oxide having stable performance without reaction or the like even when used at a high temperature. In order to increase the porosity in the porous ceramics, The porous ceramic contains needle-like or plate-like particles having an aspect ratio of 3 or more, specifically, contains at least one selected from the group consisting of silicon nitride, alumina, aluminate, aluminum borate, and mullite. It is desirable. In addition,
The aspect ratio in the present invention is represented by (the particle size in the longitudinal direction / the thickness of the particles) of the acicular or plate-like crystal particles.

Further, in order to increase the aspect ratio of the needle-like or plate-like particles, silicon nitride should contain a rare earth oxide such as Y ₂ O ₃ as a sintering aid in an amount of 1.5% by weight or more. In addition, the addition amount of SiO ₂ including oxygen as an unavoidable impurity in the silicon nitride raw material is
It is desirable that the content be 1.5% by weight or more in terms of O ₂ , and alumina is TiO ₂ , Mg
It is desirable to include sintering aid components such as O, SiO ₂ , and CaO.

In particular, when the ceramics forming the skeleton 2 are mainly composed of Al ₂ O ₃ or mullite, fine particles such as TiO ₂ of 1 μm or less are precipitated and dispersed in the main crystal phase. The strength of the body 4 can be further increased.

Next, a method for producing the porous ceramic structure of the present invention will be described. First, an organic binder, a dispersing agent, a thickener, a plasticizer, a solvent, and the like are added to a ceramic raw material powder having an average particle size of 0.1 to 2 μm for forming a skeletal portion, thereby forming a slurry. Alternatively, an alkoxide solution of the metal oxide forming the skeleton is hydrolyzed, or a precursor sol for the skeleton is prepared using a colloid solution.

Next, a spherical body for forming pores having an average diameter, that is, an average diameter of 0.01 to 10 mm is added and mixed into the slurry or the precursor sol. Examples of the spherical body include those which are burned out or eluted by heating of acrylic resin, wax, rubber, etc., or Al, Si, Sn, Pb, I which are eluted or decomposed by heat or acid.
It is made of a metal such as n, Cu, Ag or the like, whereby pores can be formed in the skeleton of the structure.

According to the present invention, the size of the pores is made uniform to increase the mechanical strength of the skeleton, and the filling ratio of the spheres in the slurry described later is increased, so that the volume ratio of the pores and the space between the pores are increased. In order to increase the contact ratio, in the diameter distribution of the spherical body shown in FIG. 2, the diameter of the spherical body is D ₁ (D ₀ × 0.7) to D ₂ within ± 30% of the average diameter D ₀ .
It is important to homogenize so that the ratio of (D ₀ × 1.3) is 90% or more of the whole sphere, and for this purpose, two or more kinds of the sphere are contained within the above range. It is desirable to use a method such as sieving with a sieve. In addition,
As the spherical body, an ellipsoid or a polyhedron of octahedron or more can also be used.

Then, the slurry or sol to which the above-mentioned spheres are added and mixed is poured into a mold having a predetermined shape. According to the present invention, in order to increase the porosity of the structure, and to deform the spheres described later. In order to enhance the properties, it is desirable to adjust the ratio of the filler in the mold so that the spherical body protrudes from the slurry surface. In addition, after the pouring, the mold can be subjected to vibration to enhance the filling of the spherical body.

Further, a pressure is applied to the mold filled with the slurry from the surface with a plate-like body or the like, and the mold is deformed and molded so that the spherical bodies come into surface contact with each other. At the time of the molding, the molded body may be heated to a predetermined temperature, for example, 50 to 150 ° C. in order to enhance the deformability of the spherical body.

Next, after removing the solvent component in the molded body, the spherical body is removed to form pores, and firing is performed at a temperature at which the remaining skeleton is densified to a relative density of 90% or more. Thus, a porous ceramic structure can be manufactured.

In order to prepare a skeleton in which nano-sized fine particles such as TiO ₂ are dispersed in Al ₂ O ₃ or mullite crystal, the atmosphere is changed to an oxidizing atmosphere during firing and the temperature is reduced to 50%.
300 or ℃ by changing to a low reducing solid solution amount of the TiO ₂ in the main crystal phase, the non-oxidizing atmosphere atmosphere during firing by the addition of equimolar MgO and TiO _2, 50 to a temperature
Change to low temperature of 300 ° C to make TiO ₂ and MgO Al ₂ O ₃
What is necessary is just to reduce the amount of solid solution to the.

The specific method of removing the sphere is, for example, when the sphere is made of an organic substance, a method of heating and burning or losing the sphere, or an organic solvent in which only the sphere is eluted. In the case where the spherical body is made of a metal, a method of decomposing and eluting the spherical body with heat or acid or the like can be suitably used. In addition,
Of the spherical bodies, it is desirable to remove those spherical bodies that are elastically deformed under the above-mentioned pressurized state.

Further, if desired, porous ceramics may be filled in the pores of the structure formed of the compact or sintered body having pores produced by the above method.

The method for filling the porous ceramics includes, for example, 1) immersing the skeleton in a slurry containing a porous ceramic raw material powder or a sol capable of producing a porous ceramic, and filling the skeleton into the pores of the skeleton. A method in which the slurry or sol is impregnated, dried by heat drying, freeze drying, supercritical drying, etc., and fired if desired. 2) Reactive gas is permeated into pores by a gas phase reaction method such as CVD into the skeleton. And a method of precipitating a predetermined compound.

Further, as a method for incorporating the above-mentioned needle-like or plate-like particles into the porous ceramic, in addition to the above-mentioned method, after filling a slurry containing a granular ceramic raw material powder, the mixture is made into a needle-like shape by sintering. By promoting plate formation, a porous ceramic having a relative density of 60% or less and a high aspect ratio can be produced in the pores of the structure.

In order to increase the above aspect ratio, needle-like or plate-like seed crystal particles are added, a sintering aid for promoting grain growth is added, and calcination is carried out for a long period of time, particularly 5 hours or more. It is desirable.

In the present invention, granules containing a raw material for porous ceramics filled in the pores of the structure can be used as the spherical body. In this case, first, for a ceramic raw material powder having a mean particle size of 0.1 to 2 μm for forming a porous ceramic,
If desired, an organic binder, a dispersant, a solvent, etc. may be added to form a slurry, or an alkoxide solution containing a metal oxide for forming a porous ceramic may be hydrolyzed, or a porous solution may be formed using a colloid solution. A precursor sol for porous ceramics is prepared, and granules having an average pore diameter of 0.01 to 10 mm are prepared by a known granulation method such as spray drying.

At this time, the porosity of the porous ceramic can be increased by adding, to the slurry or sol, an organic substance such as starch which is burned off by heating.

Then, granules for porous ceramics are added to the above-mentioned slurry or sol for the skeleton portion, mixed and poured into the molding die as described above, and the granulated powder for porous ceramics faces each other. The molding die is deformed so as to be in contact with each other and press-molded.

Thereafter, if necessary, drying is performed, and the above-mentioned molded body is heated to burn off the skeleton portion and the organic components in the porous ceramic granulated powder, and then fired at a temperature at which the skeleton portion becomes dense. A porous ceramic structure can be produced.

Further, the porous ceramic structure of the present invention can be used as a filter for separating solids such as dust, liquids, gases, etc., a supporting member thereof, a catalyst carrier, a fluid permeable member such as a molten metal, or an artificial bone. It can be suitably used as a living body substitute such as an artificial joint.

In the above-mentioned applications, for example, when used as a fluid permeable member, it can be formed in a flat plate shape and can transmit a fluid from one surface to the other surface or from one surface to one side surface, Further, it may have a tubular shape and allow the fluid flowing on the inner surface side to pass to the outer surface or the fluid flowing on the outer surface side to the inner surface. According to the present invention, isotropic mechanical properties and fluid permeation In any case, the fluid permeable member has excellent mechanical properties and fluid permeable properties.

[0044]

EXAMPLES Example 1 Alumina powder having an average particle diameter of 0.7 μm, mullite raw material powder obtained by mixing alumina and silica having an average particle diameter of 0.3 μm in a weight ratio of 72/28, and an average particle diameter of 0.1 μm. 7 μm silicon nitride powder (oxygen content 0.9
wt%) and 5% by weight of yttria having an average particle size of 1 μm and 3% by weight of alumina having an average particle size of 0.7 μm as sintering aids, and an organic binder, a dispersant, and water were added. This was added to make a slurry.

On the other hand, in the analysis by the microtrack method, the average diameter shown in Table 1 and ± 30
% Of the acrylic balls having the values shown in Table 1 (described as distribution in Table 1) were prepared by sieving as desired.

Next, the acrylic ball is mixed with the slurry so as to protrude from the surface of the slurry, flows into a gypsum mold having a thickness of 60 mmφ × 20 mm, and is vibrated to improve the filling property of the acrylic ball. Enhanced.
At this time, the ball amount was adjusted in advance so that the acrylic ball protruded from the surface of the dried slurry. Then, the plate-shaped ceramic body is placed on the top surface of the gypsum mold, caulked by screwing to the pressure shown in Table 1, dehydrated and dried, and then heated to 500 ° C. to burn off the acrylic spherical body. did.

The compact was taken out of the mold, and alumina and mullite were fired at 1650 ° C. and 1600 ° C. in air, respectively, and silicon nitride was fired at 1750 ° C. in a nitrogen atmosphere for 5 hours.

As a result of measuring the density of the skeleton portion of the obtained sintered body by the Archimedes method, the relative density was 98% or more in all cases. In addition, the dimensional density of the sample was measured to determine the porosity of the structure. Further, the average diameter of pores in one visual field and the diameter of communication holes between adjacent pores, that is, the average value of the diameter of the neck portion were measured from a SEM photograph of a cross section or a fractured surface of the structure. Further, the three-point bending strength was measured based on JISR1601.

Further, the sample was processed to a thickness of 50 mmφ × 10 mm, placed in a cylindrical housing, and the pressure loss caused when air was allowed to flow through the structure by flowing air at a flow rate of 10 m / s from one surface side. It measured with the pressure difference meter. Table 1 shows the results
It was shown to.

(Example 2) Example 1 was the same as Example 1 except that 1% by weight of TiO ₂ was added to the sample No. 12 and the firing was performed at 1500 ° C. for 5 hours in a hydrogen atmosphere, followed by annealing at 1200 ° C. in the air for 10 hours.
A porous ceramic structure was prepared in the same manner as described above, and evaluated similarly (Sample No. 12). The results are shown in Table 1.

Comparative Example Sample No. 1 of Example 1 Urethane foam (pore diameter: 0.6) in the slurry for forming the skeleton portion 3
mm) was dipped, pulled up, and dried to form a film of the slurry on the foam surface, and then fired at 1500 ° C. to burn off the urethane foam to produce a porous ceramic structure. Evaluation was performed in the same manner as Sample No. 1 (Sample No. 13). The results are shown in Table 1.

[0052]

[Table 1]

As is clear from the results shown in Table 1, a spherical body having an average diameter smaller than 0.01 mm was used, and the pore size of the structure was smaller than 0.01 mm. In No. 1, the strength of the skeleton itself was reduced, the bending strength of the structure was reduced, and the pressure loss was increased. In addition, for sample No. In No. 7, the pressure loss increased. Further, a spherical body having an average diameter larger than 10 mm was used, and the pore size of the structure was larger than 10 mm. In No. 6, the bending strength of the structure decreased. Further, the ratio of the average diameter of the spherical body within ± 30% is smaller than 90%, that is, the sample No. having a wide particle size distribution. In No. 9, the communication between the pores was deteriorated, the pressure loss was high, and the bending strength was reduced due to the presence of a ball having a large diameter in part. Further, the sample N
o. As for 13, the strength was reduced.

On the other hand, the sample No. 2
５5,8,10-12, bending strength 20MP
a and excellent pressure loss of 2 kPa or less.

Example 3 Sample No. 1 of Example 1 was used. The structure of No. 3 was immersed in a slurry containing alumina powder having an average particle size of 0.7 μm, and the pores of the structure were filled with the slurry, dried by freeze-drying, and dried in air.
Baking at 500 ° C. A sample in which the pores of No. 3 were filled with porous ceramics was prepared.

When the porosity and the average pore diameter of the obtained structure were measured by a fracture surface SEM, the relative density of the filled porous body was 32%, and the average pore diameter by a mercury intrusion method was 0.022 mm. Further, as a result of measuring the bending strength and the pressure loss at a flow velocity of 10 m / s in the same manner as in Example 1,
The bending strength was 31 MPa and the pressure loss was 1.58 MPa.

Example 4 A slurry obtained by adding starch at a ratio of 85% by weight to the slurry for porous ceramics of Example 3 was granulated by spray drying, sieved, and had an average diameter of 1.0 mm and a diameter of 0 mm. The granules had a ratio of 92% within a range of 0.7 to 1.3 mm.

The granules were prepared in the same manner as in Example 1 Used in place of the acrylic ball of No. 3 and the caulking pressure of the mold was 0.1 MPa
As a result of producing a structure in the same manner as in Example 1 except that
The porosity of the skeleton portion, that is, the volume ratio of the porous ceramic is 81%, the average pore diameter is 0.8 mm, and the communication hole diameter is 0.23.
mm, the relative density of the porous ceramic was 78%, and the average pore diameter was 0.08 mm. Further, the bending strength and the pressure loss at a flow velocity of 10 m / s were measured in the same manner as in Example 1, and as a result, the bending strength was 30 MPa and the pressure loss was 1.35 MPa.

Example 5 A raw material powder having the composition shown in Table 2 (the remainder being silicon nitride and an oxygen content of 0.9 to 1.1% by weight) was mixed with a porous material containing an organic solvent in the same manner as in Example 3. A slurry for porous ceramics was prepared. After the porous ceramic structure of No. 11 was immersed and the pores of the structure were filled with the slurry, the slurry was freeze-dried and fired at 1800 ° C. for 5 hours in a nitrogen atmosphere.

Further, this sample was evaluated in the same manner as in Example 1, and the average value of the minor axis and major axis of the crystal of the porous ceramic was determined by Luzex image processing analysis using an SEM photograph of the fracture surface of the sample. The content ratio of particles having an aspect ratio of 3 or more was measured. The results are shown in Table 2.

[0061]

[Table 2]

(Example 6) An alumina raw material comprising 30% by weight of alumina having an aspect ratio of 3, powder having an average major axis of 10 µm and the remainder having an average particle size of 0.7 µm was prepared by using TiO as a sintering aid. ₂ and 1% by weight of Mg (OH) ₂
Was added to a raw material powder containing 0.5% by weight in terms of MgO and 0.3% by weight of SiO _2, and a slurry containing an organic solvent was prepared.
o. After the porous ceramic structure of No. 3 was immersed and the pores of the structure were filled with the slurry, the slurry was freeze-dried and fired at 1400 ° C. for 5 hours in the air. The obtained sample was evaluated in the same manner as in Example 1, and the average value of the minor axis and major axis of the crystal and the aspect ratio of the porous ceramic were determined by Luzex image processing analysis using an SEM photograph of the fracture surface of the sample. The content ratio of three or more particles was measured. The results are shown in Table 3.

(Example 7) A slurry containing an organic solvent was prepared with respect to the raw material powder having the composition shown in Table 3 (the remainder being alumina). After the porous ceramic structure of No. 3 was immersed and the pores of the structure were filled with the slurry, the slurry was freeze-dried and fired in air under the conditions shown in Table 3 for 5 hours. The obtained sample was evaluated in the same manner as in Example 1, and the average value of the minor axis and major axis of the crystal and the aspect ratio of the porous ceramic were determined by Luzex image processing analysis using an SEM photograph of the fracture surface of the sample. The content ratio of three or more particles was measured. Also, from the intensity ratio of the XRD measurement, Table 3 shows a crystal phase of 97% or more as a main crystal phase. The results are shown in Table 3.

[0064]

[Table 3]

As is evident from the results in Tables 2 and 3, it was found that both had high bending strength and high fluid permeability.

[0066]

As described in detail above, according to the porous ceramic structure of the present invention, it is possible to enhance the ingress and egress characteristics of substances such as isotropic high strength and fluid permeation characteristics.

[0067]

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a tissue structure of a porous ceramic structure of the present invention.

FIG. 2 is a diagram illustrating an example of a distribution of a spherical body diameter in the method for manufacturing a porous ceramic structure of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Porous ceramic structure 2 Skeleton 3 Pores 4 Porous ceramic 5 Communication hole

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Claims (9)

[Claims] 1. Pores are present between skeleton portions made of dense ceramics, and the average pore diameter of the pores is 0.01 to 10 mm.
And the diameter of the pores is ± 30 with respect to the average pore diameter.
% Is 90% or more, adjacent pores are communicated by communication holes, and the average diameter of the communication holes is 1/4 or more of the average pore diameter. body. 2. The method according to claim 1, wherein the pores are filled with a porous ceramic having a relative density of 60% or less.
The porous ceramic structure according to any one of the preceding claims. 3. The porous ceramic has an aspect ratio of 3
3. The porous ceramic structure according to claim 2, comprising the above-mentioned needle-like or plate-like particles. 4. The method according to claim 1, wherein the needle-like or plate-like particles are silicon nitride,
4. The porous ceramic structure according to claim 3, comprising a ceramic mainly composed of at least one selected from the group consisting of alumina, aluminate, aluminum borate, and mullite. 5. A step of preparing a slurry or sol containing a ceramic raw material for forming a skeleton portion, wherein said slurry or sol has an average diameter of 0.01 to 10 mm and within ± 30% of said average diameter. Adding a spherical body for forming pores having a ratio of 90% or more, and pouring a slurry or sol to which the spherical body is added into a molding die;
A porous ceramic structure, comprising: a step of deforming the spherical body so that the spherical bodies come into surface contact with each other; and a step of removing the spherical body to form pores and then firing the remaining part. How to make the body. 6. The method for producing a porous ceramic structure according to claim 5, wherein said pores are filled with a porous ceramic having a relative density of 60% or less. 7. The method for producing a porous ceramic structure according to claim 6, wherein the spherical body for forming pores is a granule containing a ceramic raw material forming a porous ceramic and an organic substance. 8. The method for producing a porous ceramic structure according to claim 7, wherein said granules contain starch and are burned out during said pore formation. 9. A fluid permeable member comprising the porous ceramic structure according to claim 1.