JP2005239471A - Manufacturing method for ceramic porous body, and ceramic porous body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a ceramic porous body, which has a small change rate of dimension to a forming die even when the body is oxidatively fired, and to provide a ceramic porous body. <P>SOLUTION: The manufacturing method for a ceramic porous body comprises the following steps: a bubble-containing slurry preparing step, wherein bubble-containing slurry is prepared using 65-85 wt% silicon carbide, an inorganic powder comprising an oxide ceramic material, water and/or an organic solvent, and a gelatinizer; a molding step, wherein the bubble-containing slurry is poured into a molding mold for molding; a drying step for drying the molded product; and a firing step for oxidatively firing the dried molded product. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a ceramic porous body and a ceramic porous body.

In general, when a ceramic fired body is manufactured by molding a ceramic material, drying the molded product, and sintering the dried product, there are dimensional changes in each step from the molding process to the drying process and from the drying process to the firing process. Arise. The change in dimensions generally appears as shrinkage behavior, and in particular, when the ceramic material is oxidized and fired, the rate of change in dimensions increases.
As a method for producing such a ceramic fired body, Japanese Patent Application Laid-Open No. 2000-261463 discloses that a gel-like porous molded body obtained by gelling a cell-containing ceramic slurry having a hardly-sinterable ceramic powder is dried. A method for producing a ceramic porous body by degreasing and firing to obtain a ceramic porous body has been described. In this method for producing a ceramic porous body, firing is performed in an air atmosphere. The shrinkage rate of the fired product is considered to be large.

Therefore, conventionally, in order to obtain a ceramic fired body having a desired product size, ceramic firing is performed using a molding die having dimensions determined by the statistically predetermined total shrinkage rate formulas (1) and (2). The body was manufactured.

Total shrinkage (%) = {(molding die size-ceramic sintered body size) / molding die size} × 100 (1)
Mold size for molding = product size / (1-total shrinkage) (2)

However, since the total shrinkage of the ceramic fired body slightly changes depending on the temperature distribution in the firing furnace and the fluctuation of the formed body density, it is difficult to accurately adjust the dimensions of the fired body.

Therefore, in order to manufacture a fired body product having a strict dimensional tolerance, a method of machining after producing a ceramic fired body is usually employed. However, when the fired body is machined, there is a problem that the ratio of the processing cost to the product cost increases.
Moreover, when producing a large shrinkage behavior when producing a ceramic fired body, complex stress distortion may occur inside the fired body, and cracks may occur in the fired body. Such cracks are particularly likely to occur in large products.

JP 2001-261463 A

  Therefore, the present invention solves the above-described problems, and provides a method for producing a ceramic porous body and a ceramic porous body that have a small dimensional change rate with respect to a mold even when oxidized and fired.

What solves the above object is as follows.
(1) A foam-containing slurry adjustment in which a foam-containing slurry is prepared using 65 wt% to 85 wt% silicon carbide, an inorganic powder made of an oxide ceramic material, water and / or an organic solvent, and a gelling agent. Porous ceramics comprising a step, a molding step for injecting a foam-containing slurry into a molding die, a drying step for drying the molded product, and a firing step for oxidizing and firing the dried molded product Body manufacturing method.
(2) The method for producing a porous ceramic body according to (1), wherein a dimensional change rate of the fired product after the firing step with respect to the mold is ± 3.0% or less.
(3) The ceramic porous body according to (1) or (2), wherein the oxide-based ceramic material has a mixed oxide or / and composite oxide of Al ₂ O ₃ and SiO ₂ as a main component. Manufacturing method.
(4) The method for producing a porous ceramic body according to any one of (1) to (3), wherein the oxide ceramic material is mainly composed of a mixture of alumina and clay.
(5) The bubble-containing slurry adjusting step uses the inorganic powder composed of 65 wt% to 85 wt% silicon carbide and 35 wt% to 15 wt% oxide ceramic material. 4) The manufacturing method of the ceramic porous body in any one of.

(6) The method for producing a ceramic porous body according to any one of (1) to (5), wherein the forming step is performed by a gel casting method.
(7) The bubble-containing slurry adjustment step includes a slurry adjustment step of adjusting the slurry using the inorganic powder, water and / or an organic solvent, and a gelling agent, adding a foaming agent to the slurry, and forming bubbles. The method for producing a ceramic porous body according to any one of the above (1) to (6), wherein the bubble introduction step to be introduced is performed.
(8) The bubble-containing slurry adjustment step includes a slurry adjustment step of adjusting a slurry using the inorganic powder, water and / or an organic solvent, a gelling agent, and a foaming agent, and bubble introduction for introducing bubbles into the slurry. The method for producing a ceramic porous body according to any one of (1) to (7), wherein the step is performed.
(9) The method for producing a ceramic porous body according to any one of (1) to (8), wherein the firing temperature is 1200 to 1400 ° C. in the firing step.
Moreover, what solves the said objective is as follows.
(10) A molded product made from a bubble-containing slurry prepared using 65 wt% to 85 wt% silicon carbide and an inorganic powder made of an oxide-based ceramic material is oxidized and fired, and contains the bubbles A porous ceramic body in which the dimensional change rate of the oxidized fired product is ± 3.0% or less with respect to a molding die for molding a molded product made from the slurry.

Moreover, what solves the said objective is as follows.
(11) A ceramic porous body formed by oxidizing and firing inorganic powder made of silicon carbide and an oxide-based ceramic material, wherein the porous body includes a ceramic matrix and a plurality of pores formed by the matrix. And the ceramic matrix is composed of the silicon carbide, the silicon oxide formed around the silicon carbide by the oxidation firing, and the ceramic material subjected to the oxidation firing.
(12) The ceramic porous body according to (10) or (11), wherein the ceramic porous body has an average pore diameter of 10 μm to 200 μm.
(13) The ceramic porous body according to any one of (10) to (12), wherein the ceramic porous body has fine pores formed between ceramic particles forming the ceramic matrix.
(14) The ceramic porous body according to any one of (10) to (13), wherein the oxide ceramic material is a mixed oxide or / and a composite oxide of Al ₂ O ₃ and SiO ₂ .
(15) The porous ceramic body according to any one of (10) to (14), wherein the silicon carbide content in the porous ceramic body is 65% by weight to 85% by weight.
(16) The ceramic porous body according to any one of (10) to (15), wherein the porosity of the ceramic porous body is 60 to 80%.

The method for producing a porous ceramic body according to the present invention includes a method of containing bubbles by using 65 wt% to 85 wt% silicon carbide, an inorganic powder made of an oxide ceramic material, water and / or an organic solvent, and a gelling agent. A foam-containing slurry adjustment process for adjusting the slurry, a molding process for injecting the foam-containing slurry into a molding die, a drying process for drying the molded article, and an oxidized firing of the dried molded article The firing step is performed.
For this reason, according to the present invention, it is possible to produce a porous ceramic body having a small dimensional change rate with respect to the molding die even by oxidation firing.

Moreover, the ceramic porous body of the present invention is obtained by oxidizing and firing a molded product made from a foam-containing slurry prepared by using 65 to 85% by weight of silicon carbide and an inorganic powder made of an oxide-based ceramic material. In addition, the dimensional change rate of the oxidized fired product with respect to the mold for molding the molded product made from the bubble-containing slurry is ± 3.0% or less.
For this reason, the ceramic porous body of the present invention has a small rate of dimensional change with respect to the mold even when oxidized and fired.
The ceramic porous body of the present invention is a ceramic porous body formed by oxidizing and firing inorganic powder made of silicon carbide and an oxide-based ceramic material, the porous body comprising a ceramic matrix and the matrix. The ceramic matrix has a plurality of formed pores, and the ceramic matrix is composed of the silicon carbide, silicon oxide formed around the silicon carbide by oxidation firing, and the ceramic material subjected to oxidation firing.
For this reason, the ceramic porous body of the present invention has a small rate of dimensional change with respect to the mold even when oxidized and fired.

The manufacturing method of the ceramic porous body which is an Example of this invention is demonstrated in detail using an accompanying drawing.
FIG. 1 is an explanatory view for explaining the structure of the ceramic porous body, and FIG. 2 is a partially enlarged view of the explanatory view shown in FIG.
The method for producing a porous ceramic body 1 according to the present invention is a method using 65 wt% to 85 wt% silicon carbide, an inorganic powder made of an oxide ceramic material, water and / or an organic solvent, and a gelling agent. A bubble-containing slurry adjustment step for adjusting the contained slurry, a molding step for injecting the bubble-containing slurry into a molding die, a drying step for drying the molded product, and an oxidized baking of the dried molded product The baking process for this is performed.

First, the bubble-containing slurry adjustment step will be described.
The bubble-containing slurry adjustment step of the embodiment of the present invention includes a slurry adjustment step of adjusting a slurry using an inorganic powder, water and / or an organic solvent, and a gelling agent, a foaming agent is added to the slurry, and bubbles are removed. The bubble introduction process to introduce is performed.
In the embodiment of the present invention, the slurry adjustment step is performed by mixing silicon carbide powder, an oxide ceramic material, water, and a gelling agent. The mixing is preferably performed while pulverizing silicon carbide powder or the like. Silicon carbide is mixed at 65 wt% to 85 wt% with respect to the inorganic powder. If the silicon carbide powder content is 65 wt% to 85 wt%, the expansion effect due to oxidation firing can be sufficiently obtained, and the dimensional change rate of the ceramic porous body with respect to the mold is sufficiently small. In other words, the dimensional accuracy of the ceramic porous body with respect to the mold is increased. On the other hand, when silicon carbide is less than 65% by weight, it is considered that the expansion effect due to oxidation firing cannot be sufficiently obtained and the dimensional change rate is not sufficiently reduced. Moreover, when silicon carbide exceeds 85 weight%, although the expansion effect by oxidation baking can fully be acquired, there exists a possibility that a baked product may crack.

As the oxide-based ceramic material, for example, alumina, silica stone, mullite, cordierite, clay mineral, zirconia, feldspar, porcelain stone, glass and the like are preferably used. The oxide ceramic material is preferably a mixed oxide or / and composite oxide of Al ₂ O ₃ and SiO ₂ as a main component. As oxide ceramic materials, alumina and clay minerals are particularly preferable. The clay mineral is preferably Kibushi clay. The oxide-based ceramic material is not limited to these, and any oxide material may be used as long as it has a property of being baked to each other with a shrinkage behavior under oxidation firing. In the embodiment of the present invention, it is preferable to use a mixture of alumina and Kibushi clay as the oxide forming material. It is preferable to mix 5 wt% to 20 wt% of alumina. Moreover, it is preferable to mix 5 to 20 weight% of clay minerals.

The bubble-containing slurry adjustment step preferably uses an inorganic powder composed of 65% to 85% by weight of silicon carbide and 35% to 15% by weight of an oxide ceramic material. If the slurry is adjusted at such a blending ratio, the expansion effect due to oxidation firing can be sufficiently obtained, and in particular, the dimensional change rate of the ceramic porous body with respect to the mold is reduced. In other words, the dimensional accuracy of the ceramic porous body with respect to the mold is increased.
As the silicon carbide powder used in the examples of the present invention, those having an average particle diameter of 0.1 to 10 μm, particularly 1 to 3 μm are preferably used. As the oxide ceramic material powder, it is preferable to use one having an average particle diameter of 1 to 5 μm. The pulverization is preferably performed until the average particle size of silicon carbide is about 1 to 20 μm. The pulverization is preferably performed by a pot mill, a ball mill or the like.

Water and / or an organic solvent is used as a medium for turbidizing the silicon carbide powder and the oxide ceramic material powder. Preferably, it is water. As the organic solvent, alcohols such as methanol and ethanol are preferably used. Further, a dispersing agent may be added to the ceramic slurry in order to uniformly contain the ceramic powder. As the dispersant, a known dispersant is used. For example, polycarboxylic acid-based dispersants, specifically, ammonium polycarboxylate and sodium polycarboxylate can be used.
The water and / or organic solvent is preferably added in an amount of 25 to 40 parts by weight, particularly 30 to 35 parts by weight, based on 100 parts by weight of the silicon carbide powder and the oxide ceramic material powder.

As the gelling agent, a synthetic resin or a natural polymer can be used.
As the synthetic resin, either a thermoplastic resin or a thermosetting resin can be used, and it is particularly preferable to use a thermosetting resin. As the thermosetting resin, it is preferable to use a polyurethane resin, an epoxy resin or the like, and it is particularly preferable to use methacrylamide (organic monomer) and methylene bisacrylamide (crosslinking agent). As the thermoplastic resin, vinyl resins, polyamide resins, acrylic resins and the like are preferable, and polyvinyl alcohol and the like are particularly preferable. Moreover, as natural polymers, natural polysaccharides such as cellulose, methylcellulose, egg protein, starch and agar are preferable, and methylcellulose is particularly preferable. Examples of gelling agents include radically polymerizable organic monomers (monofunctional monomers such as methacrylamide, acrylic acid, dimethylaminoethyl methacrylate, methoxypolymonomethacrylate, methacrylic acid, and n-vinylpyrrolidone, Difunctional monomers such as diamine, N, N′-methylenebisacrylamide, polydimethylacrylate, triallylamine) can be used. In particular, N, N′-methylenebisacrylamide is preferable. The gelling agent may be any gelling agent as long as it can be dispersed and gelated by silicon carbide powder and oxide ceramic material powder and decomposes and vaporizes in the firing step. The gelling agent is preferably added in an amount of 5 to 20 parts by weight, particularly 10 to 15 parts by weight, based on 100 parts by weight of the silicon carbide powder and the oxide ceramic material powder. In addition, a known lubricant and thickener may be added to the slurry.
Moreover, it is preferable to carry out vacuum degassing after the slurry adjustment or during the slurry adjustment step.

Next, a bubble introduction step for adding bubbles to the slurry and introducing bubbles will be described.
The bubble introduction step of the example is performed by adding a foaming agent to the slurry and stirring. The foaming agent is preferably a surfactant, a protein foaming agent or the like. As the surfactant, it is preferable to use an anionic surfactant such as alkylbenzene sulfonic acid or a cationic surfactant such as higher alkyl amino acid. Bubbles are formed in the slurry by adding a surfactant and stirring vigorously. Stirring is preferably performed in a nitrogen atmosphere. Specifically, the slurry is put into a beaker so that the final bubble introduction amount is 20 to 70%, and a predetermined amount of an initiator, a catalyst, and a surfactant are added. It is preferable to stir for ~ 5 minutes. Bubbles introduced into the slurry by the bubble introduction step become a plurality of pores 5 as shown in FIG. 1 after the molding step, the drying step, and the firing step.

In the embodiment of the present invention, a gelation accelerator is added in the bubble introduction step. Moreover, an initiator is added when an initiator is required for polymerization of an organic monomer or the like. As the gelation accelerator, it is preferable to use tetramethylethyldiamine, hydrogen peroxide compound, azo or diazo compound, particularly tetramethylethyldiamine. As the initiator, it is preferable to use sodium persulfate, ammonium persulfate, or the like, particularly ammonium persulfate. Although depending on the gelling agent, the gelation accelerator and the initiator are preferably added to the slurry when the surfactant is added.
The bubble introduction step is not limited to being performed by adding a surfactant to the slurry and stirring. For example, bubbles may be introduced into the slurry by feeding an inert gas such as nitrogen gas into the slurry.
The amount of bubbles introduced and the diameter of the bubbles formed in the slurry in the bubble introduction step can be adjusted by the amount of surfactant added, the viscosity of the slurry, the strength of stirring, and the like.

Next, a molding process in which the bubble-containing slurry is injected into a molding die and molded will be described. In the present invention, the molding step is performed by a gel casting method.
The bubble-containing slurry prepared in the bubble introduction step is poured into a molding die, and after a predetermined time has passed, the slurry is gelled (solidified), and then the gelled molded product is taken out from the molding die.
Next, a drying process for drying the molded product is performed. In the drying process, the size of the molded product shrinks from the size of the molded product before drying (the size of the molding die). The molded product taken out from the mold is preferably dried while adjusting the humidity. As a drying temperature, it is preferable that it is 15-50 degreeC, especially 25-40 degreeC. Moreover, as humidity of a drying process, it is 0-100%, It is especially preferable that it is 40-95%. The drying time is preferably 40 to 100 hours.
The shrinkage ratio (hereinafter referred to as dry shrinkage ratio) of the dried molded product with respect to the molding die is obtained by the following equation (3).

Drying shrinkage ratio (%) = {(molding mold dimension−dry molding dimension) / molding mold dimension} × 100 (3)

The drying shrinkage is preferably about 3 to 6%.

Next, a firing process for oxidizing and firing the dried molded product will be described.
In the embodiment of the present invention, it is preferable that the dried molded product is fired in an air atmosphere. The firing temperature is lower than the melting point of silicon carbide and oxide ceramic materials. Specifically, the firing temperature is preferably 1000 ° C to 1600 ° C, particularly 1200 ° C to 1400 ° C. The firing time is preferably 1.5 to 2.5 hr. By firing, the above-described gelling agent, gelation accelerator, catalyst, and water are decomposed or vaporized, and the ceramic porous body 1 shown in FIG. 1 is produced.
A ceramic porous body 1 shown in FIGS. 1 and 2 is a ceramic composed of silicon carbide 3, silicon oxide 7 formed around silicon carbide 3 by oxidation firing, and oxide-based ceramic material 4 subjected to oxidation firing. It has a matrix 2, a plurality of pores 5 formed by the matrix 2, fine pores 6 formed between ceramic matrix particles, and medium pores 8 formed at portions where the pores 5 are adjacent to each other.

  By the oxidation firing, the silicon carbide 3 particles are oxidized, and silicon oxide 7 is formed on the surface of the silicon carbide 3. Silicon carbide 3 and silicon oxide 7 are sintered using an oxide ceramic material as a sintering aid to constitute the ceramic matrix 2 described above. And since the silicon oxide 7 is produced | generated around the silicon carbide 3 particle | grains, the volume of the silicon carbide 3 part containing the silicon oxide 7 increases from the volume of the silicon carbide simple substance before baking, and the oxide system by which oxidation baking was carried out The volume of the ceramic material portion 4 is smaller than the volume of the oxide ceramic material before the oxidation firing. And in a baking process, the volume of the ceramic porous body 1 increases as a whole from the volume of the dried molded object.

The firing shrinkage {shrinkage of the fired body (ceramic porous body) with respect to the dried molded product, plus is shrinkage, minus is swelling)} can be calculated by the following equation (4).

Firing shrinkage ratio (%) = {(Dry molded product size−Baking product size) / Dry molded product size} × 100 (4)

The firing shrinkage is preferably about −6% to −3%. According to the production method of the present invention, since the dried molded article expands in the firing step, the dimensional change rate (total shrinkage) of the fired product with respect to the molding die is smaller than that produced by the conventional production method. .

The dimensional change rate (total shrinkage rate, plus is shrinkage, minus is swelling) of the fired product after the firing step for the molding die can be calculated by the following equation using the above-described dry shrinkage rate and firing shrinkage rate.

Dimensional change rate (%) = {1- (1-dry shrinkage rate / 100) × (1-fired shrinkage rate / 100)} × 100 (5)

The dimensional change rate is preferably ± 3.0% or less, and particularly preferably ± 1.0% or less. If the dimensional change rate is about this level, the change in the dimension with respect to the molding die is small, so that it is not necessary to process to a desired dimension after firing, or a desired dimension can be obtained with a little processing.

Moreover, the volume change rate (plus is shrinkage and minus is expansion) of the fired product after the firing step with respect to the mold can be calculated by the following equation using the above-described dimensional change rate.

Volume change rate (%) = {1− (1−dimensional change rate / 100) ³ } × 100 (6)

The volume change rate is preferably ± 9.0% or less, and particularly preferably ± 3.0% or less. If the volume change rate is about this level, the change in dimension relative to the molding die is small, so that it is not necessary to process to a desired dimension after firing, or a desired dimension can be achieved with a little processing.

  According to the method for producing a ceramic porous body of the present invention, when the raw material slurry of the ceramic porous body 1 is molded using a molding die and then dried, the molded product exhibits shrinkage behavior, and when the dried molded product is oxidized and fired, a fired body is obtained. (Ceramic porous body 1) exhibits expansion behavior with respect to the dried molded product. As a result, the shrinkage behavior in the drying step and the expansion behavior in the firing step cancel each other, and the dimensional change rate of the ceramic porous body 1 with respect to the molding die becomes small. As mentioned above, according to the manufacturing method of the ceramic porous body of this invention, the ceramic porous body with a small dimensional change rate with respect to a shaping | molding die can be manufactured.

Next, the ceramic porous body which is an Example of this invention is demonstrated using FIG. 1, FIG.
The porous ceramic body 1 of the present invention is obtained by oxidizing and firing a molded product made of a foam-containing slurry prepared by using 65 to 85% by weight of silicon carbide and an inorganic powder made of an oxide-based ceramic material. In addition, the dimensional change rate of the oxidized fired product with respect to the molding die produced from the bubble-containing slurry is ± 3.0% or less.
The ceramic porous body 1 of the present invention is a ceramic porous body 1 formed by oxidizing and firing inorganic powder made of silicon carbide 3 and an oxide-based ceramic material. The ceramic matrix 2 includes a plurality of pores 5 formed by the matrix 2, and the ceramic matrix 2 includes silicon carbide 3, silicon oxide 7 formed around the silicon carbide 3 by oxidation firing, and the ceramic material 4 subjected to oxidation firing. It is configured.

The ceramic porous body 1 of the present invention has fine pores 6 formed between ceramic particles forming the ceramic matrix 2. In addition, as shown in FIGS. 1 and 2, the ceramic matrix 2 has middle pores 8 formed at portions where the pores 5 are adjacent to each other.
As shown in FIGS. 1 and 2, the ceramic porous body 1 has a ceramic matrix 2, pores 5, fine pores 6, and medium pores 8.
As shown in FIGS. 1 and 2, the ceramic matrix 2 is composed of silicon carbide 3, silicon oxide 7 formed around the silicon carbide 3, and oxide-based ceramic material 4 that is oxidized and fired. In the embodiment of the present invention, the silicon carbide particles are formed via silicon oxide 7 formed around silicon carbide 3 by oxidation firing or oxide ceramic material 4 subjected to oxidation firing. The oxide ceramic material plays a role as a sintering aid. Further, the silicon carbide 3 particles may be directly bonded without using the silicon oxide 7 or the oxidized ceramic material 4 subjected to oxidation and firing.

  As described above, the ceramic porous body 1 is produced by oxidizing and firing a bubble-containing slurry prepared using an inorganic powder having a silicon carbide content of 65 wt% to 85 wt%. It is preferable that the oxidation firing of the molded product made from the bubble-containing slurry prepared using the inorganic powder made of silicon carbide and the oxide-based ceramic material is performed as in the manufacturing method described above. In the Example of this invention, adjustment of a bubble containing slurry is performed by adding a foaming agent and stirring to the slurry which mixed silicon carbide powder, oxide type ceramic material, water, and the gelatinizer. And this porous ceramic body 1 of this invention is manufactured by inject | pouring this bubble containing slurry into a shaping | molding die, shape | molding by the gel casting method, and passing through the drying process and the baking process by oxidation baking.

As shown in FIG. 2, the silicon oxide 7 is formed around the silicon carbide 3 by oxidizing and firing silicon carbide particles. Thus, when the silicon oxide 7 is formed on the surface of the silicon carbide 3, it is considered that the volume of the silicon carbide 3 including the silicon oxide 7 is larger than the volume of the silicon carbide alone before firing. Moreover, since the oxide-based ceramic material 4 that has been oxidized and fired serves as a sintering aid, the ceramic porous body 1 has practical properties while retaining the properties of the silicon carbide 3. As silicon carbide and oxide ceramic materials, it is preferable to use those described above. As described above, the oxide ceramic material is preferably a mixed oxide of Al ₂ O ₃ and SiO ₂ and / or a composite oxide. The oxide ceramic material is particularly preferably alumina and clay minerals, and the clay mineral is preferably kibushi clay. The oxide ceramic material becomes an oxide mainly composed of Al ₂ O ₃ and SiO ₂ by being oxidized.
In addition, as above-mentioned, the ceramic porous body may contain things other than the silicon carbide 3, the silicon oxide 7, and the oxide type ceramic material 4. FIG.

The silicon carbide content in the matrix porous body 1 is preferably 65 to 85% by weight. If the content of silicon carbide 3 in the matrix porous body after oxidation firing is about this level, a ceramic porous body having sufficient properties of silicon carbide 3 is obtained.
In the ceramic matrix 2, a plurality of interparticle holes are formed as shown in FIG. The fine pores 6 are pores formed between the silicon carbide 3, the silicon oxide 7, and the oxide ceramic material particles 4. The fine pores 6 are formed as pores 5 described later, open pores communicating with the outside, or isolated closed pores. The average pore diameter of the fine pores 6 is preferably 0.1 to 5 μm, particularly preferably 0.1 to 2 μm.
Specifically, the ceramic matrix 2 is mainly filled with silicon carbide particles 3 whose surfaces are oxidized and covered with a film of silicon oxide 7, and Al ₂ O ₃ particles and clay particles 4 are formed around the silicon carbide particles 3. Is distributed. Fine pores (voids) 6 described later exist between the particles.

The pores 5 are formed in the ceramic matrix as shown in FIGS. The pores 5 are formed as closed pores formed in the ceramic matrix that do not communicate with the outside, or open pores that communicate with the outside. The shape of the pores 5 is preferably a substantially spherical shape, a substantially elliptical spherical shape, or the like, and particularly preferably a substantially spherical shape.
As shown in FIG. 1 and FIG. 2, the middle pores 8 are opened in the inner wall of the matrix that constitutes the pores 5, and are formed as channels that connect adjacent pores. By forming the middle pores 8, a plurality of pores 5 communicate with each other.
The ceramic porous body preferably has a high porosity and a small pore diameter. The pore size distribution of the ceramic porous body is preferably narrow. A ceramic porous body has high bending strength due to its narrow pore size distribution. In addition, the ceramic porous body has high bending strength due to the small pores and the narrow pore size distribution.
The average pore diameter of the pores 5 is preferably 10 to 300 μm, particularly preferably several tens of μm to 200 μm. Moreover, the bending strength of the Example of this invention will be 5-15 Mpa. The pores 5 are preferably formed uniformly in the ceramic porous body 1. The pores 5 may be distributed so as to be inclined to a part of the ceramic porous body. The porosity of the ceramic porous body 5 is preferably 60 to 80%, particularly preferably 65 to 75%.

The dimensional change rate of the oxidized fired product with respect to the molding die for molding a molded product produced from the bubble-containing slurry is preferably ± 3.0% or less, and particularly preferably ± 1.0% or less. Is preferred. With such a dimensional change rate, there is no need to process to a desired dimension after firing, or a desired dimension can be achieved with a little processing.
Since the ceramic porous body 1 of the embodiment of the present invention has the above-described configuration, the dimensional change rate with respect to the mold is small. In the case of the ceramic porous body according to the embodiment of the present invention, since the dimensional change rate with respect to the mold is small, it is not necessary to process it into a desired shape after firing, or it is possible to obtain a desired dimension with a little processing. it can.

Next, the manufacturing method of the ceramic porous body of Example 1-6 of this invention is demonstrated.
(Example 1)
(Adjustment of bubble-containing slurry)
300 g of silicon carbide having an average particle size of 1.3 μm (GC8000F, manufactured by Fujimi Incorporated), 100 g of alumina having an average particle size of 3.5 μm (AM-21, manufactured by Sumitomo Chemical Co., Ltd.), Kibushi clay (Mizumoto Motoyama) Kibushi clay, Seto Ceramics Co., Ltd. (100 g), water (240 ml), methacrylamide (methacrylamide, Wako Pure Chemical Industries, Ltd.) 51.6 g as a gelling agent, methylenebisacrylamide (N, N ′) as a crosslinking agent -2.6 g of methylene bisacrylamide (manufactured by Wako Pure Chemical Industries, Ltd.) was charged into a polyethylene pot mill (1 liter of wide-mouth bottle, manufactured by ASONE Co., Ltd.), and mixed and ground at room temperature for 24 hr to prepare a slurry. The weight ratio of silicon carbide, alumina, and Kibushi clay is 60:20:20.
After the above-mentioned slurry was vacuum degassed for 5 to 10 minutes, 4.2 g of a foaming agent (K-204, manufactured by Nippon Oil & Fats Co., Ltd.) and methyl ethyl diamine as a gelation accelerator under normal pressure and nitrogen atmosphere (N, N, N ′, N′-tetramethylethyldiamine, Wako Pure Chemical Industries, Ltd.) 0.63 ml, ammonium persulfate (ammonium peroxodisulfate, manufactured by Wako Pure Chemical Industries, Ltd.) 0.48 g as an initiator was added Then, the mixture was stirred for 3 minutes using a stirrer (Pal Cooking, manufactured by Tescom Co., Ltd.) to prepare a bubble-containing slurry having bubbles in the slurry.

(Molding)
Next, under normal pressure and a nitrogen atmosphere, the bubble-containing slurry was poured into a non-permeable mold (acrylic, diameter 70 mm) and allowed to stand for 1 hr, and then the gelled molded product in the mold was taken out. The gelled molded product was dried for 51 hr at a humidity of 95 to 40% and a temperature of 25 to 40 ° C. The molded product gelled by drying contracted.
(Baking)
And the dried molding was baked using the electric furnace (fast heating furnace B-2 type, Kyowa High Heat Co., Ltd. product).
Firing was performed by raising the temperature from room temperature to the highest temperature (firing temperature) at 100 ° C./hr, firing at the highest temperature for firing (firing temperature) for 2 hr, and then stopping heating and cooling in the furnace. The firing temperature was about 1300 ° C. The molded product dried by oxidation firing expanded.

(Example 2)
Example 2 differs from Example 1 only in the weight ratio of silicon carbide, alumina, and kibushi clay used to prepare the bubble-containing slurry. Other steps are the same as those in the first embodiment.
In the preparation of the slurry of Example 2, 350 g of silicon carbide, 75 g of alumina, and 75 g of kibushi clay are mixed. The weight ratio of silicon carbide, alumina, and Kibushi clay is 70:15:15.

(Example 3)
Example 3 differs from Example 1 only in the weight ratio of silicon carbide, alumina, and kibushi clay used to prepare the bubble-containing slurry. Other steps are the same as those in the first embodiment.
In the preparation of the slurry of Example 3, 400 g of silicon carbide, 50 g of alumina, and 50 g of Kibushi clay are mixed. The weight ratio of silicon carbide, alumina, and Kibushi clay is 80:10:10.

Example 4
Example 4 differs from Example 1 only in the weight ratio of silicon carbide, alumina, and kibushi clay used to prepare the bubble-containing slurry. Other steps are the same as those in the first embodiment.
In the preparation of the slurry of Example 4, 400 g of silicon carbide, 22.2 g of alumina, and 22.2 g of kibushi clay are mixed. The weight ratio of silicon carbide, alumina, and Kibushi clay is 90: 5: 5.

(Example 5)
Example 5 is different from Example 3 only in the weight ratio of alumina and Kibushi clay used for preparation of the bubble-containing slurry. Other steps are the same as those in the first embodiment.
In the preparation of the slurry of Example 5, 400 g of silicon carbide, 75 g of alumina, and 25 g of kibushi clay are mixed. The weight ratio of silicon carbide, alumina, and Kibushi clay is 80: 15: 5.

(Example 6)
Example 6 is different from Example 3 only in the weight ratio of alumina and Kibushi clay used to prepare the bubble-containing slurry. Other steps are the same as those in the first embodiment.
In the preparation of the slurry of Example 6, 400 g of silicon carbide, 25 g of alumina, and 75 g of kibushi clay are mixed. The weight ratio of silicon carbide, alumina, and Kibushi clay is 80: 5: 15.

(Comparative Example 1)
Comparative Example 1 differs from Example 1 only in the preparation of the bubble-containing slurry. Other steps are the same as those in the first embodiment.
(Adjustment of bubble-containing slurry)
500 g of silicon carbide having an average particle size of 1.3 μm (GC8000F, manufactured by Fujimi Incorporated), 240 ml of water, 51.6 g of methacrylamide (manufactured by Wako Pure Chemical Industries, Ltd.) as a gelling agent, and methylene bisacrylamide (a crosslinking agent) N, N′-methylenebisacrylamide (manufactured by Wako Pure Chemical Industries, Ltd.) was put into a polyethylene pot mill (1 liter of wide-mouth bottle, manufactured by ASONE Co., Ltd.), and mixed and ground at room temperature for 24 hours to prepare a slurry.

(Comparative Example 2)
Comparative Example 2 is different from Example 1 only in that the adjustment of the bubble-containing slurry and the firing temperature are 1550 ° C. Other steps are the same as those in the first embodiment.
(Adjustment of bubble-containing slurry)
520 g of alumina having an average particle size of 0.4 μm and 5.0 μm (P172SB and AC44B5, manufactured by Pesine Japon Co., Ltd.), 114.4 ml of water, and methacrylamide as a gelling agent (methacrylamide, manufactured by Wako Pure Chemical Industries, Ltd.) 24 .3 g, methylene bisacrylamide (N, N′-methylene bisacrylamide, manufactured by Wako Pure Chemical Industries, Ltd.) as a cross-linking agent was charged into a polyethylene pot mill (1 liter of wide-mouth bottle, manufactured by AS ONE Co., Ltd.), and 24 hours at room temperature. The slurry was prepared by mixing and grinding.

(Comparative Example 3)
Comparative Example 3 differs from Example 1 only in that the adjustment of the bubble-containing slurry and the firing temperature are 1500 ° C. Other steps are the same as those in the first embodiment.
(Adjustment of bubble-containing slurry)
1000 g of zirconia having an average particle size of 3.3 μm (UZY-8H, manufactured by Daiichi Elemental Chemical Co., Ltd.), 155.5 ml of water, 33.8 g of methacrylamide (manufactured by Wako Pure Chemical Industries, Ltd.) as a gelling agent, and a crosslinking agent Methylene bisacrylamide (N, N'-methylene bisacrylamide, manufactured by Wako Pure Chemical Industries, Ltd.) is put into a polyethylene pot mill (1 liter of wide-mouth bottle, manufactured by AS ONE Co., Ltd.), mixed and ground at room temperature for 24 hours, and slurry Adjusted.

(Comparative Example 4)
Comparative Example 4 is different from Example 1 only in that the adjustment of the bubble-containing slurry and the firing temperature are 1300 ° C. Other steps are the same as those in the first embodiment.
(Adjustment of bubble-containing slurry)
Cordierite with an average particle size of 2.2 μm (SS-600, manufactured by Marusu Glaze Co., Ltd.) 420 g, water 157.3 ml, methacrylamide (manufactured by Wako Pure Chemical Industries, Ltd.) 33.5 g as a gelling agent, cross-linking agent Methylene bisacrylamide (N, N'-methylene bisacrylamide, manufactured by Wako Pure Chemical Industries, Ltd.) is put into a polyethylene pot mill (1 liter of wide-mouth bottle, manufactured by AS ONE Co., Ltd.), mixed and ground at room temperature for 24 hours, and slurry Adjusted.

The drying shrinkage rate was calculated by the above-described equation (3) using the diameter dimensions of the dried molded products of Examples 1 to 6 and Comparative Examples 1 to 4 and the diameter dimension of the molding die. The results shown in Table 1 and Table 2 shown in FIG.
Table 1 shows the calcining shrinkage rate calculated by the equation (4) using the diameter dimensions of the dried molded products and the diameter dimensions of the calcined bodies measured in Examples 1 to 6 and Comparative Examples 1 to 4. The results shown in Table 2 were obtained.
And when the dimensional change rate was calculated | required by Formula (5) using the drying shrinkage rate calculated by Formula (3) and the baking shrinkage rate calculated by Formula (4), the results as shown in Table 1 and Table 2 were obtained. became.

Also, as shown in Table 1, when alumina: kibushi clay = 1: 1 and the silicon carbide content is increased (in the case of Example 1, Example 2, Example 3, and Example 4), it is shown in FIG. As shown in graph 1, as silicon carbide increased, the drying shrinkage decreased, and the firing shrinkage increased in the negative direction (expansion increased).
Further, using the data in Table 1, when the silicon carbide content was 80% by weight and the mixing ratio of alumina / clay was changed, the change in the drying shrinkage rate was slow as shown in graph 2 in FIG. However, the firing shrinkage ratio changed greatly, and particularly the change in shrinkage ratio on the alumina-rich side was large.

(Experimental result)
As shown in Tables 1 and 2, the dimensional change rate of the fired bodies of Example 1 to Example 6 is sufficiently smaller than the dimensional change rate of Comparative Examples 1 to 4. Therefore, the fired body according to the example of the present invention has higher dimensional accuracy with respect to the molding die than the fired body according to the comparative example.
Further, from FIG. 5, it is considered that the content of silicon carbide 3 is particularly preferably 65 to 85% by weight. Further, it can be considered from FIG. 5 that when the silicon carbide content is in the vicinity of 80% by weight, the dimensional change rate becomes the smallest and has the highest dimensional accuracy.
Further, from FIG. 6, it is considered that when the silicon carbide content is fixed at 80% by weight, the dimensional change rate decreases from 1: 1 to the clay rich side in the alumina / clay mixing ratio.
Further, in the case of Comparative Example 1 in which the content of silicon carbide was 100% by weight, cracks frequently occurred in the firing step, which was not practical. This is considered to be because the expansion ratio at the time of firing is too large in addition to the fact that the effect as a sintering aid cannot be obtained.

FIG. 1 is an explanatory view for explaining the structure of a ceramic porous body according to the present invention. FIG. 2 is a partially enlarged view of the structure of the ceramic porous body shown in FIG. FIG. 3 is Table 1 showing experimental results of Examples 1 to 6. FIG. 4 is Table 2 showing experimental results of Comparative Examples 1 to 4. FIG. 5 is a graph 1 showing a dimensional change rate, a drying shrinkage rate, and a firing shrinkage rate when the silicon carbide content is increased with alumina / clay = 1: 1. FIG. 6 is a graph 2 showing the dimensional change rate, the drying shrinkage rate, and the firing shrinkage rate when the silicon carbide content is 80% by weight and the mixing ratio of alumina / clay is changed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic porous body 2 Ceramic matrix 3 Silicon carbide 4 Oxide type ceramic material 5 Pore 6 Fine pore 7 Silicon oxide

Claims (16)

A bubble-containing slurry adjustment step of adjusting bubble-containing slurry using 65 wt% to 85 wt% silicon carbide, an inorganic powder made of an oxide-based ceramic material, water and / or an organic solvent, and a gelling agent; A molding step of injecting a foam-containing slurry into a molding die and molding, a drying step for drying the molded product, and a firing step for oxidizing and firing the dried molded product are performed. A method for producing a ceramic porous body. The method for producing a porous ceramic body according to claim 1, wherein a dimensional change rate of the fired product after the firing step with respect to the molding die is ± 3.0% or less. _{3. The} method for producing a ceramic porous body according to claim 1, wherein the oxide-based ceramic material contains a mixed oxide or / and composite oxide of Al ₂ O ₃ and SiO ₂ as a main component. The method for producing a ceramic porous body according to any one of claims 1 to 3, wherein the oxide ceramic material is mainly composed of a mixture of alumina and clay. 5. The air bubble-containing slurry adjusting step uses an inorganic powder composed of 65 wt% to 85 wt% silicon carbide and 35 wt% to 15 wt% oxide ceramic material. The manufacturing method of the ceramic porous body as described in 2. The method for producing a porous ceramic body according to any one of claims 1 to 5, wherein the forming step is performed by a gel casting method. The bubble-containing slurry adjustment step includes a slurry adjustment step of adjusting a slurry using the inorganic powder, water and / or an organic solvent, and a gelling agent, and a bubble that introduces bubbles while adding a foaming agent to the slurry. The method for producing a ceramic porous body according to any one of claims 1 to 6, wherein the introduction step is performed. The bubble-containing slurry adjustment step includes a slurry adjustment step of adjusting a slurry using the inorganic powder, water and / or an organic solvent, a gelling agent, and a foaming agent, and a bubble introduction step of introducing bubbles into the slurry. The method for producing a ceramic porous body according to any one of claims 1 to 7, which is performed. The method for producing a ceramic porous body according to any one of claims 1 to 8, wherein in the firing step, a firing temperature is 1200 ° C to 1400 ° C. A molded product made from a bubble-containing slurry prepared using 65 wt% to 85 wt% silicon carbide and an inorganic powder made of an oxide ceramic material is oxidized and fired, and made from the bubble-containing slurry. A porous ceramic body, wherein a dimensional change rate of an oxidized fired product with respect to a forming die for forming the formed product is ± 3.0% or less. A porous ceramic body formed by oxidizing and firing inorganic powder made of silicon carbide and an oxide-based ceramic material, the porous body having a ceramic matrix and a plurality of pores formed by the matrix, Furthermore, the ceramic matrix is composed of the silicon carbide, silicon oxide formed around the silicon carbide by oxidation firing, and the ceramic material subjected to oxidation firing. The ceramic porous body according to claim 10 or 11, wherein an average pore diameter of the ceramic porous body is 10 µm to 200 µm. The ceramic porous body according to any one of claims 10 to 12, wherein the ceramic porous body has fine pores formed between ceramic particles forming the ceramic matrix. The ceramic porous body according to any one of claims 10 to 13, wherein the oxide-based ceramic material is a mixed oxide or / and composite oxide of Al ₂ O ₃ and SiO ₂ . The ceramic porous body according to any one of claims 10 to 14, wherein a content of silicon carbide in the ceramic porous body is 65 wt% to 85 wt%. The ceramic porous body according to any one of claims 10 to 15, wherein a porosity of the ceramic porous body is 60% to 80%.

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