JP2016210659A - Ceramic plate-like body and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic plate-like body, upon heating and cooling, particularly, upon rapid heating and rapid cooling, in which a temperature difference is hard to occur between the central region and the peripheral region.SOLUTION: Provided is a ceramic-like body 10 having the part of a plate-like porous body composed of ceramic. The plate-like porous part has a first region 21 with the first pore size viewed from the plane and a second region 22 with a second pore size being the pore size smaller than a first pore size 21. The space between the first region 21 and the second region 22 is further provided with a pore size transition region 23 in which the pore size is reduced from the first region 21 over the second region 22. In the plane view, preferably, the central region and the peripheral region being the region including the peripheral edge of the plate-like body while surrounding the central region are provided, the central region is composed of one or a plurality of the first regions 21, and the peripheral region is composed of the second region 22.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a ceramic plate-like body suitably used as a setter for an object to be fired and a method for producing the same.

  When firing ceramic electronic parts or glass, firing is generally performed by placing an object to be fired on a setter called a shelf board or a floor board. In this case, when placing a to-be-fired object having a large size on the setter, or when placing many to-be-fired objects on the setter, it is necessary to enlarge the placement surface of the object to be fired in the setter. . However, when the size of the mounting surface is increased, a temperature difference is likely to occur between the central area and the peripheral area of the mounting surface. Since the occurrence of the temperature difference may affect the quality of the fired product, such as warping of the fired product, it is desired to prevent the temperature difference from occurring on the mounting surface.

For the purpose of performing uniform heating during firing, Patent Document 1 describes a porous ceramic setter having excellent air permeability and high thermal conductivity. In this setter, ceramic fibers or whiskers and ceramic particles selected from SiC, BN, AlN, BeO, MoSi ₂ , TiN, and ZrB ₂ having an average particle diameter of 5 to 100 μm are bonded with a heat-resistant inorganic binder. It has an entangled structure between fibers.

  As in Patent Document 1, for the purpose of performing uniform heating during firing, Patent Document 2 includes a raw material containing ceramic powder and an organic compound or clay for imparting shape retention to the powder. A molding step for forming a molded product, a drying / firing step for drying the molded product at a temperature of 1300 to 1800 ° C. after drying the molded product, and a flat plate having a uniform thickness. The manufacturing method of the ceramic board which has the cutting process cut | disconnected in a shape is described.

Japanese Patent Laid-Open No. 10-255101 JP 2005-29462 A

  However, even if the techniques described in Patent Documents 1 and 2 are adopted, it is not easy to reduce the temperature difference generated between the central area and the peripheral area of the setter placement surface to a satisfactory level. In particular, it is not easy to reduce the temperature difference during heating or cooling in the firing process, particularly during rapid heating or rapid cooling.

  An object of the present invention is to provide a ceramic plate-like body suitably used as a setter, which can eliminate the various disadvantages of the above-described conventional technology.

The present invention has a plate-like porous body portion made of ceramics,
The portion of the porous body has a first region having a first pore diameter and a second region having a second pore diameter smaller than the first pore diameter when viewed in plan. And
The present invention provides a ceramic plate-like body further having a pore diameter transition region in which the pore diameter decreases from the first region to the second region between the first region and the second region.

The present invention is also a method for producing the ceramic plate-like body,
Supply a chiller containing ceramic raw material powder and gelling agent into the casting mold,
Forming a molded body by gelling the thriller,
The bottom of the casting mold is cooled to freeze the molded body to obtain a frozen body in which ice crystals grow from the bottom to the top of the molded body,
Drying the frozen body, removing the frozen ice to obtain a dried body,
Next, subjecting the dried body to firing,
The bottom of the casting mold has two heat transfer sites with different heat transfer rates, and the size of ice crystals formed on the molded body according to the difference in heat transfer rate from the bottom to the molded body The present invention provides a method for producing a ceramic plate-like body with different valences.

  According to the present invention, since the plate-like body is made of ceramics, the plate-like body can be used in a harsh environment, and the pore diameter of a part of the plate-like body is compared with other portions. The advantage resulting from making it larger or smaller can be utilized in harsh environments. In particular, according to the present invention, there is provided a ceramic plate-like body that hardly causes a temperature difference between the central region and the peripheral region during heating and cooling, particularly during rapid heating and rapid cooling. When the plate-like body is made of a porous body having open pores, the air permeability in the central area and the peripheral area can be easily controlled.

FIG. 1 is a perspective view showing an embodiment of a ceramic plate-like body of the present invention. 2 is a cross-sectional view taken along line II-II in FIG. 3A to 3C are process diagrams showing a method for producing the ceramic plate-like body shown in FIG. 4A is a cross-sectional view of the state shown in FIG. 3C, and FIG. 4B shows the degree of heat transfer rate when cooling is performed from the state shown in FIG. 4A. FIG. FIG. 5A is a schematic diagram showing a dispersion state of ceramic raw material powder particles in a state before cooling, and FIG. 5B is a schematic diagram showing an array state of ceramic raw material powder particles in a state after cooling. FIG. FIG. 6 is a thermographic image when the ceramic plate obtained in Example 1 is rapidly cooled after being heated. FIG. 7 is a thermographic image when the ceramic plate obtained in Comparative Example 1 is heated and then rapidly cooled.

  The present invention will be described below based on preferred embodiments with reference to the drawings. FIG. 1 shows an embodiment of the ceramic plate-like body of the present invention. 2 is a cross-sectional view taken along line II-II in FIG. The ceramic plate-like body 10 shown in these drawings is used as a setter during firing of an object to be fired. The ceramic plate 10 has a plate-like main body 11. The main body 11 is made of a porous body made of ceramics. The main body 11 has a first surface 11a and a second surface 11b opposite to the first surface 11a. The main body 11 has a rectangular shape in plan view. However, the shape of the main body 11 in a plan view is not limited to a rectangle, and can take various shapes depending on the shape and number of objects to be fired. Whatever the shape of the main body 11 in plan view, the thickness of the main body 11 is preferably the same at an arbitrary position.

  The ceramic plate-like body 10 has leg portions 12 in addition to the main body portion 11. The legs 12 are provided at the corners of the main body 11. As described above, the main body portion 11 has a rectangular shape in plan view, and the leg portions 12 are located at the four corners of the main body portion 11. The leg portion 12 is suspended from the second surface 11b of the main body portion. The leg portion 12 is formed integrally with the main body portion 11. Further, the leg portion 12 is formed of the same ceramic material as that of the main body portion 11. However, it is not necessary that the leg portion 12 is a porous body.

  The first surface 11a of the main body 11 serves as a mounting surface for the fired product when the ceramic plate 10 is used, that is, when the fired product is fired. The first surface 11a is a flat surface. That is, the first surface 11a is a flat surface and not a curved surface. The first surface 11a is a smooth surface. That is, the first surface 11a is smooth, and there are no convex portions or concave portions. Since the first surface 11a is a flat and smooth surface as described above, the material to be fired can be stably placed on the first surface 11a when the material to be fired is fired. Calcination can be performed. Depending on the shape of the object to be fired, the first surface 11a may be a curved surface, or a convex portion or a concave portion may be formed on the first surface 11a. On the other hand, the surface shape of the second surface 11b is not particularly limited.

  As described above, the main body 11 is made of a porous body. The main body 11 has three regions having different pore diameters. Specifically, the main body 11 has a first region 21 having a first pore diameter when viewed in plan and a second region having a second pore diameter that is smaller than the first pore diameter. Region 22 and a pore diameter transition region 23 that is located between the first region and the second region and in which the pore diameter decreases from the first region to the second region. The first region 21, the second region 22, and the pore diameter transition region 23 are integrally formed. “Integrally formed” means that the first region 21, the second region 22, and the pore diameter transition region 23 are not joined by any joining means, but all the regions 21, 22, and 23 are made of ceramics. It means that it is a continuous structure. According to a preferred manufacturing method described later, the ceramic plate 10 in which the first region 21, the second region 22, and the pore diameter transition region 23 are integrally formed can be manufactured. If it is adopted, the ceramic plate-like body 10 in which these regions are not integrally formed may be obtained. When the regions 21, 22 and 23 are integrally formed, the temperature difference between the central region and the peripheral region of the main body 10 can be further reduced when the ceramic plate 10 is heated and / or cooled. This is preferable because it is possible.

The main body 11 has a central area and a peripheral area that surrounds the central area and includes the peripheral edge of the main body 11 in a plan view. Specifically, the central area is composed of one first area 21, and the peripheral area is composed of a second area 22. Furthermore, a pore diameter transition region 23 exists between the central region and the peripheral region. The first region 21 located in the central region can be formed to have a rectangular shape that is substantially similar to the shape of the main body 11 in the plan view of the main body 11, for example. However, the shape of the first region 21 in plan view does not need to be similar to the shape of the main body portion 11 in plan view. Further, the shape of the first region 21 in plan view need not be rectangular. For example, the shape of the first region 21 in plan view may be a circle or a polygon other than a rectangle. From the viewpoint of minimizing the temperature difference between the central region and the peripheral region, the normal line drawn at an arbitrary position on the periphery of the first region 21 in plan view intersects with the peripheral edge of the main body 11. The length is preferably the same at any position on the periphery. For example, the first region 21 is a circle, the second region 22 and the pore diameter transition region 23 are annulus, the circle of the first region 21, the ring of the second region 22, and the ring of the pore diameter transition region 23. And are preferably concentric. Moreover, the length until the normal drawn to an arbitrary position on the periphery of the first region 21 in a plan view intersects with the peripheral edge of the main body 11 differs at any two or more positions on the periphery. In this case, the value of L _max / L _min which is the ratio of the longest length L _max to the shortest length L _min is preferably 8 or less, particularly 4 or less.

  The first region 21 preferably has a constant pore diameter, that is, the first pore diameter D1 over the entire region in the thickness direction and the in-plane direction. Similarly, it is preferable that the second region 22 also has a constant pore diameter, that is, a second pore diameter D2 over the entire region in the thickness direction and the in-plane direction. The pore diameters D1 and D2 have a relationship of D1> D2. The pore diameter transition region 23 has a pore diameter similar to the pore diameter D1 of the first region 21 at the boundary with the first region 21, and the second region 22 at the boundary with the second region 22. It has the same pore diameter as the pore diameter D2. In the pore diameter transition region 23, the pore diameter decreases from D1 to D2 from the boundary portion with the first region 21 to the boundary portion with the second region 22. For example, when the pore diameter of the pore diameter transition region 23 is focused on, the pore diameter is continuously increased from the position closer to the first area 21 toward the position closer to the second area 22. Are reduced. Alternatively, a mode in which the pore diameter monotonously decreases in a step shape can be mentioned. If the pore diameter is reduced, the degree of the reduction is not limited, and may be reduced linearly, quadraticly, or exponentially or logarithmically. May be. The pore diameter transition region 23 only needs to have at least a portion where the pore diameter decreases from a position closer to the first region 21 toward a position closer to the second region 22, and the effects of the present invention are exhibited. Within the range, although the pore diameter is changed in the pore diameter transition region 23, the change is not reduced, and it is not hindered that there is a site with increase / decrease in the pore diameter. However, in the pore diameter transition region 23, the pore diameter decreases continuously or stepwise from the position closer to the first area 21 toward the position closer to the second area 22, It is preferable because the temperature difference between the two regions 22 can be easily reduced.

  The first region 21, the second region 22, and the pore diameter transition region 23 are preferably made of the same ceramic material. The fact that each region 21, 22 and 23 is made of the same ceramic material increases the sense of unity in all regions, which is advantageous in maintaining strength and heat conduction. In particular, when each of the regions 21, 22 and 23 is made of the same ceramic material, the sense of unity is further enhanced. As a result, the temperature difference between the central region and the peripheral region of the main body 10 can be further reduced when the ceramic plate 10 is heated and / or cooled.

  When the ceramic plate-like body 10 of the present embodiment having the configuration as described above is used as a setter when firing an object to be fired, the central region of the main body 11 during heating and cooling in the firing process. And the temperature difference between the peripheral region and the conventional setter can be made smaller. The reason for this is as follows. The first region 21, which is a region having a large pore diameter, has high air permeability and a high effect of heat convection, so that an excellent heat exchange function can be expected. Therefore, the first region 21 having high air permeability is disposed in the central region, and the second region 22 having a small pore diameter is disposed in the peripheral region surrounding the central region, so that the central region that is difficult to be heated can be easily formed during heating. On the other hand, at the time of cooling, the central region that is difficult to be cooled can be easily cooled. As a result, the temperature difference between the central region and the peripheral region during heating and cooling can be reduced. It is. In addition, by providing the second region 22 having a small pore diameter in the peripheral region surrounding the central region, the ceramic plate-like body 10 can be given strength necessary for handling. In addition to this, if the pore diameter transition region 23 is located between the first region 21 and the second region, the temperature difference between the central region and the peripheral region can be easily controlled. In particular, when the main body 11 is made of a porous body having open pores, the air permeability in the central area and the peripheral area of the main body 11 can be easily controlled. This also makes it possible to reduce the temperature difference between the central area and the peripheral area. The ceramic plate-like body 10 having the main body 11 in such a state can be suitably manufactured by a method described later.

  In particular, as illustrated in Example 1 described later, it is preferable that the ceramic plate-like body 10 is cooled so that the temperature in the central region is lower than the temperature in the peripheral region. The reason for this is as follows. When the ceramic plate-like body 10 is used as a setter for an object to be fired, for example, the object to be fired is often placed in the center area of the setter. When firing is performed in such a mounted state and then cooling is performed, in the central area of the setter, the cooling proceeds with respect to the sum of the heat capacity of the central area and the heat capacity of the fired product. Therefore, if the cooling proceeds so that the temperature in the central region is lower than the temperature in the peripheral region, the heat capacity of the fired product can be offset by the heat capacity in the peripheral region of the setter, and the cooling is performed quickly. Can do.

  From the viewpoint of making the above advantageous effects more remarkable, the pore diameter D1 of the first region 21 is preferably 30 μm or more and 500 μm or less, more preferably 40 μm or more and 400 μm or less, and 50 μm or more and 300 μm or less. Is more preferable. The pore diameter D2 of the second region 22 is preferably 1 μm or more and 100 μm or less, more preferably 30 μm or more and 80 μm or less, provided that the pore diameter D2 of the first region 21 is smaller than the pore diameter D1. More preferably, it is as follows. The pore diameter of each region is obtained by observing the cross section of the main body 11 with a scanning electron microscope, taking a cross-sectional image, measuring the diameter of any 20 pores existing in the field of view, and calculating the average value thereof. Ask for it. When the pore is not circular, the diameter of the pore refers to the maximum transverse length of the pore of interest.

  From the viewpoint of making the advantage of forming the first region 21, the second region 22, and the pore diameter transition region 23 in the main body 11 even more remarkable, the porosity of the second region 22 is higher than the porosity of the first region 21. Is preferably lower. In particular, the porosity of the first region 21 is preferably 50% or more and 99% or less, more preferably 60% or more and 90% or less, and still more preferably 70% or more and 90% or less. On the other hand, on the condition that the porosity of the second region 22 is lower than the porosity of the first region 21, it is preferably 50% or more and 99% or less, and more preferably 50% or more and 90% or less. More preferably, it is 50% or more and 85% or less. The porosity of the pore diameter transition region 23 is preferably lower than the porosity of the first region 21 and higher than the porosity of the second region 22. On condition that this condition is satisfied, for example, the porosity of the pore diameter transition region 23 is preferably 55% or more and 99% or less, more preferably 55% or more and 90% or less, and 55% or more and 85%. More preferably, it is as follows. The ceramic plate-like body 10 having the main body 11 in such a state can be suitably manufactured by a method described later.

  The porosity is a physical property value defined by the apparent porosity measured by the Archimedes method. The porosity of the first region 21, the second region 22, and the third region 23 of the main body 11 is measured by the following method. The main body 11 is processed with a cutter, and the first region 21, the second region 22, and the pore diameter transition region 23 are separately taken out, and the apparent porosity is measured according to JIS R1634 (vacuum method). In the ceramic plate 10 manufactured according to the manufacturing method described later, since almost all of the pores are open pores, the open porosity becomes the value of the porosity as it is.

The temperature difference between the central region and the peripheral region during heating and during cooling from the viewpoint of further reducing the proportion of the sum S1 of the area of the first region 21 in plan view, with respect to the area S _T of the main body portion 11 in a plan view It is preferably 1% or more and 80% or less, more preferably 1% or more and 60% or less, and even more preferably 3% or more and 50% or less. From the same viewpoint, the proportion of the second total area of the region 22 S2 in plan view is preferably 80% or more and 10% or less of the area _{S T} of the main body portion 11 in a plan view, at least 20% 75 % Or less, more preferably 25% or more and 75% or less. From the same viewpoint, the proportion of the third total area of the region 23 S3 in plan view is preferably 80% or less than 5% relative to the area S _T of the main body portion 11 in a plan view, at least 10% 70 % Or less, more preferably 20% or more and 60% or less.

  In the ceramic plate 10 of the embodiment shown in FIG. 1, only one first region 21 is formed in the central region of the main body 11, but instead of this, two or more first regions 21 are formed in the main body. You may form in the 11 central area. In this case, two or more first regions 21 are surrounded by the pore diameter transition region 23.

  Various materials can be used as the ceramic material constituting the ceramic plate 10. Examples thereof include alumina, silicon carbide, silicon nitride, zirconia, mullite, magnesia, and titanium diboride.

  Next, a preferred method for manufacturing the ceramic plate 10 shown in FIGS. 1 and 2 will be described with reference to FIGS. 3, 4 and 5. First, as shown in FIG. 3A, a casting mold 30 is prepared. The casting mold 30 has a substantially rectangular bottom surface 31 in plan view and four side surfaces 32 rising from the periphery of the bottom surface 31, and the top surface is open. The bottom surface 31 and the side surface 32 define a recess S that opens upward. The recess S has a shape complementary to the target ceramic plate 10. For the purpose of forming the first region 21, the second region 22 and the pore diameter transition region 23 in the main body 11 of the ceramic plate-like body 10, the bottom central region 31a of the bottom surface 31 is formed of a material having a relatively low heat transfer rate. In addition, it is advantageous to form the bottom peripheral region 31b surrounding the bottom central region 31a with a material having a relatively high heat transfer rate.

  Examples of the material used to form the bottom central region 31a include various polymer materials, glass, and SUS, which is a metal having a relatively low thermal conductivity. Polymer materials include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, polyamide resins, acrylic resins such as polyacrylic acid and methyl methacrylate, and vinyl resins such as polyvinyl chloride and polystyrene. Etc. On the other hand, examples of the material used for forming the bottom peripheral region 31b include various metals (those having a higher thermal conductivity than SUS), carbon, and high thermal conductive ceramics such as SiC and AlN.

The heat transfer rate Q (J / s) described above is a physical quantity represented by Q = kA (T ₁ −T ₂ ) / d. In the formula, k represents the thermal conductivity, A represents the area of the bottom central region 31a or the bottom peripheral region 31b, d represents the thickness of the bottom central region 31a or the bottom peripheral region 31b, and T ₁ and T ₂ represent the bottoms. The temperature in each surface of the center area 31a or the bottom peripheral area 31b is represented. In the present embodiment, as described above, the heat transfer rate Q is set by making the constituent materials different between the bottom central region 31a and the bottom peripheral region 31b, thereby making the thermal conductivity represented by the constant k different. It is different.

  Under the state shown in FIG. 3A, the slurry 41 is supplied into the recess S of the casting mold 30 as shown in FIG. 3B. The slurry 41 preferably contains ceramic raw material powder and a gelling agent as a medium. The slurry 41 preferably contains water or a water-soluble organic solvent as a medium.

The ceramic raw material powder contained in the slurry 41 is a raw material for the ceramic material constituting the target ceramic plate 10. The particle size of the ceramic raw material powder is preferably 0.01 μm or more and 100 μm or less, expressed as a volume cumulative particle size D ₅₀ at a cumulative volume of 50 vol% by a laser diffraction / scattering particle size distribution measurement method, and is 0.05 μm or more and 10 μm or less. More preferably, it is 0.1 μm or more and 5 μm or less.

  The concentration of the ceramic raw material powder contained in the slurry 41 determines the density of the molded body subjected to firing, and the sintering shrinkage rate for sufficiently increasing the strength of the sintered body obtained from the molded body. In consideration, it is preferably 4 to 30 parts by volume, more preferably 6 to 25 parts by volume, and more preferably 8 to 20 parts by volume with respect to 100 parts by volume of the medium. Is more preferable.

  The type and concentration of the gelling agent contained in the slurry 41 are related to the degree of gelation of the slurry 41. From this viewpoint, the concentration of the gelling agent contained in the slurry 41 is preferably 0.1 parts by mass or more and 10 parts by mass or less, and 0.5 parts by mass or more and 7 parts by mass or less with respect to 100 parts by mass of the medium. More preferably, it is more preferably 1 part by mass or more and 4 parts by mass or less.

  The gelling agent is used as a binder for binding particles of ceramic raw material powder in a dried product obtained by freeze drying described later. For this purpose, N-alkylamide polymers, N-isopropylacrylamide polymers, sulfomethylated acrylamide polymers, N-dimethylaminopropyl methacrylamide polymers, polyalkylacrylamide polymers are used as gelling agents. Molecule, alginic acid, sodium alginate, ammonium alginate, polyethyleneimine, cellulose derivative system, polyacrylate, polyethylene glycol, polyethylene oxide, polyvinyl alcohol, polyvinylpyrrolidone, carboxyvinyl polymer, starch, gelatin, agar, pectin, glucomannan, xanthan gum , Locust bean gum, carrageenan gum, guar gum, gellan gum, lignin sulfonate, polyacrylamide, polyvinyl ester, isobutylene - it can be used maleic acid anhydride copolymers, vinyl acetate, epoxy resin, phenol resin and urethane resin. These gelling agents can be used individually by 1 type or in combination of 2 or more types.

  The gelling agent preferably has a weight average molecular weight in the range of 500 to 2,000,000, more preferably 2,000 to 1,500,000, and even more preferably 4,000 to 1,000,000.

  In addition to the components described above, other components may be added to the slurry 41. For example, a dispersant for smoothly dispersing the ceramic raw material powder in the medium can be blended. As the dispersant, for example, polycarboxylic acid ammonium salt, polyacrylic acid ammonium salt, polyethyleneimine and the like can be used. It is preferable that the compounding quantity of a dispersing agent is 0.5 to 3 mass parts with respect to 100 mass parts of ceramic raw material powders.

  When the slurry 41 is supplied into the recess S of the casting mold 30, the slurry 41 is gelled. In order to gelate, for example, the slurry 41 may be cooled. The cooling temperature can be set to, for example, 1 ° C. or more and 12 ° C. or less. By the gelation of the slurry 41, the slurry 41 acquires shape retention, and a molded body 41a is obtained as shown in FIG.

  Next, the compact 41a shown in FIG. 4 (a) is subjected to a freezing step. The freezing step can be performed by bringing a cooling device 43 into contact with the outer surface of the bottom surface 31 of the casting mold 30 as shown in FIG. 4B, for example. By subjecting the molded body 41a to the freezing step, freezing proceeds in one direction, that is, the direction from the lower surface to the upper surface of the molded body 41a, so that ice crystals grow, and the oriented structure of the ceramic raw material powder in the molded body 41a is increased. It is formed. That is, rearrangement of the ceramic raw material powder particles occurs. This is shown in FIGS. 5 (a) and 5 (b). Fig.5 (a) is an enlarged view which shows typically the state of the slurry 41 before gelatinizing. As shown in the figure, in the slurry 41 in a state before gelation, the ceramic raw material powder particles 42 are randomly and uniformly dispersed in the slurry 41. This uniform dispersion state is maintained even in the state of the molded body 41a in which the slurry 41 is gelled. When the freezing process proceeds from the state shown in FIG. 5A, the water in the molded body 41a becomes ice. The generation of ice starts from the lower surface side of the molded body 41a, which is the portion closest to the cooling device 42, and proceeds toward the upper surface side of the molded body 41a. Since ice formation occurs in one direction, the ice crystals are columnar. As a result, the ceramic raw material powder particles 43 contained in the compact 41a are rearranged while being pushed away by the ice columnar crystals. In the rearranged state, the ceramic raw material powder particles 43 form a substantially honeycomb structure as shown in FIG. The pores of the honeycomb extend along the thickness direction of the formed body 41a, that is, the cooling direction of the formed body 41a.

Incidentally, as described above, the bottom surface 31 of the casting mold 30 in which the molded body 41a is accommodated has a bottom center region 31a and a bottom peripheral region 31b having different heat transfer rates. The bottom center region 31a is a first heat transfer region having a first heat transfer rate, and the bottom peripheral region 31b is a second heat transfer region having a heat transfer rate higher than the first heat transfer rate. The first heat transfer area is located in the central area of the bottom 31, and the second heat transfer area is located in the peripheral area that surrounds the central area and includes the peripheral edge of the bottom 31. Accordingly, the bottom center region 31a, which is the first heat transfer region, and the bottom peripheral region 31b, which is the second heat transfer region, differ in how heat is transmitted. Specifically, in the molded body 41a, the cooling proceeds relatively quickly in a portion corresponding to the bottom peripheral area 31b having a high heat transfer rate. In contrast, in the molded body 41a, the cooling proceeds relatively slowly in a portion corresponding to the bottom central region 31a having a high heat transfer rate. The arrows shown in FIG. 4B indicate the heat transfer rate, the large arrows mean the high heat transfer rate, and the small arrows mean the low heat transfer rate. Generally, when the liquid is solidified by cooling, it is known that if the cooling rate is high, the size of the crystal generated by the solidification becomes small, and conversely, if the cooling rate is low, a large crystal is formed. This phenomenon is the same in the present manufacturing method. In the portion indicated by the large arrow in FIG. 4B, cooling rapidly proceeds to produce small ice crystals, while in the portion indicated by the small arrow in FIG. Proceeds slowly, producing large ice crystals. As a result, returning to FIG. 5B, the size of the pores in the substantially honeycomb-like structure is caused by the formation of small ice crystals in the portion of the molded body 41a corresponding to the bottom peripheral region 31b. is _{D b} is relatively small. On the other hand, of the molded body 41a, the size D _a of the holes in the substantially honeycomb structure due to generation crystals of large ice in portions corresponding to the bottom center region 31a is relatively large. And out of the molded body 41a, the portions corresponding to the boundary and its vicinity of the bottom peripheral region 31b and the bottom central region 31a, progressively decreases the size of the pores from large pores D _b to the small holes D _a As such, ice crystals form. As described above, in this manufacturing method, the bottom 31 of the casting mold 30 has the bottom central region 31a and the bottom peripheral region 31b, which are two heat transfer sites having different heat transfer speeds, from the bottom 31 to the molded body 41a. The size of ice crystals formed on the compact 41a is varied according to the difference in heat transfer speed.

  A known cooling device can be used for freezing. Specifically, a method of bringing the outer surface of the bottom surface 31 of the casting mold 30 into contact with a solid such as a cooled metal plate, a method of bringing the bottom surface 31 of the casting mold 30 into contact with a cooled liquid, or the like can be used. . In addition, for example, by circulating ethanol cooled to a predetermined temperature from one side to the other side so that it flows without stagnation or undulations near the liquid level of ethanol, the temperature near the liquid level can be reduced. You may use the ethanol cooling device hold | maintained uniformly. By applying the ethanol cooling device having such a configuration, the bottom surface of the casting mold 30 is held in contact with the cooled ethanol liquid surface, and freezing can be performed in one direction upward from the bottom. Thereby, the ceramic plate-like body 10 with less variation in pore diameter can be produced.

  The freezing temperature in the freezing step is not limited as long as the water in the gel or slurry can be frozen to produce ice. In addition, depending on the kind of gelling agent, it may not freeze at -10 degreeC or more due to interaction with water, Therefore The freezing temperature of -10 degreeC or less is preferable. For example, it is preferable to immerse the casting mold 30 in ethanol cooled to −15 ° C. using the ethanol cooling device described above and freeze in one direction from the bottom.

  In this way, a frozen body in which ice crystals grow from the bottom to the top of the compact is obtained. Next, the frozen body 44 is taken out from the casting mold 30 and dried as shown in FIG. 3C, and the ice in the frozen body 44 is removed. In the drying step, it is preferable to use a drying method that prevents cracks by gradually replacing ice with pores while suppressing a difference in drying speed between the inside and outside of the frozen body. Specifically, ice can be replaced with pores by freeze-drying the frozen body, or by immersing in a water-soluble organic solvent or a water-soluble organic solvent aqueous solution and air-drying. For example, when the frozen body is immersed in a water-soluble organic solvent or a water-soluble organic solvent aqueous solution, the ice in the frozen body is melted and mixed with the water-soluble organic solvent. By performing such an operation once or a plurality of times, first, the portion that was ice in the frozen body is replaced with a water-soluble organic solvent. Thereafter, when the frozen body in which the inside of the frozen body is replaced with a water-soluble organic solvent is dried in the atmosphere or under reduced pressure, the portion that was ice in the freezing step is replaced with pores.

  In the drying process using a water-soluble organic solvent, a water-soluble organic solvent that does not erode the gelling agent and has higher volatility than water is used. Specific examples include, but are not limited to, methanol, ethanol, isopropyl alcohol, acetone, and ethyl acetate. By performing drying using these water-soluble organic solvents alone or in combination with a plurality of types once or a plurality of times, pores are formed in the portion that was ice in the frozen body.

  Next, the dried body produced by drying is subjected to a firing step. The target ceramic plate 10 is obtained by this firing. Baking can generally be performed in air. The firing temperature may be selected appropriately depending on the type of ceramic raw material powder. The same applies to the firing temperature.

  By the above method, the target ceramic plate 10 is obtained. As described above, the ceramic plate-like body 10 can be suitably used as a setter for firing ceramic products such as a shelf board and a floor board, and can also be used as a kiln tool other than a setter, such as a firewood or a beam. Furthermore, it can also be used for applications other than kiln tools, such as various jigs and various structural materials.

  As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, in the embodiment, the pore diameter in the central region of the plate-shaped main body 11 is larger than the pore diameter in the peripheral region, but the first region 21 having a large pore diameter and the second region 22 having a small pore diameter The arrangement position is not limited to this. For example, depending on the specific application of the ceramic plate-like body of the present invention, the first region 21 having a large pore diameter is arranged in the peripheral region of the plate-like body, and the second region 22 having a small pore diameter is arranged at the center of the plate-like body. It can also be placed in the area.

  Further, in the bottom portion 31 of the casting mold 30 used in the method for manufacturing the ceramic plate-like body 10 described above, the constituent material is made different between the bottom central region 31a and the bottom peripheral region 31b, thereby being expressed by a constant k. By changing the thermal conductivity, the heat transfer rate Q was changed, but instead, the bottom central region 31a and the bottom peripheral region 31b are made of the same material, and the thicknesses of both the regions 31a and 31b are made different. The heat transfer rate Q may be varied by making it different.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, “part” means “part by mass”.

[Example 1]
A ceramic plate 10 shown in FIGS. 1 and 2 was manufactured according to the method shown in FIGS. Water, alumina particles, and a dispersing agent are mixed for 1 minute using a hybrid mixer. Separately, an aqueous solution in which gelatin as a gelling agent is dissolved in hot water is prepared, and both are mixed to prepare slurry 41. Obtained. The slurry 41 thus obtained comprises alumina particles D ₅₀ is 0.5 [mu] m, a water slurry further containing gelatin and a dispersing agent. The amount of alumina particles relative to 100 parts by volume of water in the slurry was 11 parts by volume. The concentration of gelatin was 3% by mass with respect to water. The concentration of the dispersant was 1.5% by mass with respect to the raw material.

  A casting mold 30 having a square shape in plan view was used. The dimension of the casting mold 30 in plan view was 135 mm × 135 mm. The bottom portion of the casting mold 30 was made of a square acrylic plate in plan view of the bottom central region 31a, and a bottom peripheral region 31b surrounding the acrylic plate was made of an aluminum plate. The dimension of the acrylic plate was 95 mm × 95 mm. The slurry 41 was supplied to the casting mold 30. The supply amount of the slurry 41 was set so that the depth in the recess S was 5 mm. The casting mold 30 was left in the refrigerator, and the slurry 41 was cooled and gelled to obtain a molded body 41a.

  Next, the casting mold 30 was frozen at −10 ° C. using ethanol. The obtained frozen body 44 was taken out from the casting mold 30 and dried for 24 hours with a vacuum freeze-drying apparatus (FDU-1100 manufactured by Tokyo Science Instruments Co., Ltd.).

The dried body thus obtained was calcined at 1600 ° C. for 3 hours in the atmosphere. The fired product was polished on both sides, and the thickness of the main body 11 was set to 2 mm. In this way, a target ceramic plate 10 was obtained. About the obtained ceramic plate-like body 10, the pore diameter and the porosity of the main-body part 11 were measured by the above-mentioned method. The pore diameter was measured at intervals of 5.0 mm at the position of a perpendicular line that was virtually drawn from the center of the main body 11 toward one side. When the increase in pore diameter ([d _i -d _{i + 1} ] / d _i × 100) at two measurement positions adjacent to the center from the periphery is 8% or less, the two places have the same pore diameter. It judges and makes it belong to the 1st field 21 or the 2nd field 22. When the increment exceeds 8%, the two locations belong to the pore diameter transition region 23. The results are shown in Table 1 below.

[Comparative Example 1]
In Example 1, the bottom 31 of the casting mold 30 was formed only from an aluminum plate. Except for this, a ceramic plate 10 was obtained in the same manner as in Example 1. The main body 11 in this ceramic plate has the same pore diameter (50 μm) at any position.

[Evaluation]
An alumina refractory (65 × 65 × 2 mmt) was placed on the ceramic plate-like bodies obtained in the examples and comparative examples, assuming a fired product, and heated. Heating was performed so that the temperature at the center of the plate-like body was 500 ° C. The ceramic plate-like body heated to this temperature was taken out of the heating furnace into the atmosphere and rapidly cooled. The time until the temperature of the central part of the plate-like body was cooled to about 400 ° C. was measured. Moreover, the minimum temperature in the peripheral part of this plate-shaped object when the temperature of the center part of a plate-shaped object became about 400 degreeC was measured. The measurement of temperature was performed using thermography (CPA-640A manufactured by Chino Co., Ltd.). The results are shown in Table 2 below. Moreover, what was image | photographed about Example 1 is shown in FIG. 6, and what was image | photographed about the comparative example 1 is shown in FIG. 7 as an external appearance photograph which colored the measured temperature distribution by thermography.

  As is clear from the results shown in Table 2, the ceramic plate-like body 10 obtained in Example 1 was different in pore diameter between the central area 21 and the peripheral area 22 and formed the pore diameter transition area 23. As a result, it can be seen that the temperature difference between the central region and the peripheral region is smaller than that of the ceramic plate-like body of Comparative Example 1. Moreover, it turns out that it cools in a short time. Further, as apparent from the comparison between FIG. 6 and FIG. 7, in Comparative Example 1 in FIG. 7, the temperature in the peripheral region is lower than that in the central region and the temperature difference is large, whereas in Example 1 in FIG. It can be seen that the temperature is slightly higher than the temperature in the central region and the temperature difference is small.

DESCRIPTION OF SYMBOLS 10 Ceramic plate-like body 11 Main body part 11a 1st surface 11b 2nd surface 12 Leg part 21 1st area | region 22 2nd area | region 23 Pore diameter transition area | region 30 Casting type | mold 31 Bottom surface 32 Side surface 41 Slurry 41a Molding body 42 Cooling device 44 Freezing body

Claims (10)

It has a plate-shaped porous body made of ceramics,
The portion of the porous body has a first region having a first pore diameter and a second region having a second pore diameter smaller than the first pore diameter when viewed in plan. And
A ceramic plate-like body further comprising a pore diameter transition region in which a pore diameter decreases from the first region to the second region between the first region and the second region.   The ceramic plate-like body according to claim 1, wherein the first region, the second region, and the pore diameter transition region are made of the same ceramic material.   The ceramic plate-like body according to claim 1 or 2, wherein the first region, the second region, and the pore diameter transition region are integrally formed. A central area in a plan view, and a peripheral area that surrounds the central area and includes a peripheral edge of the plate-like body;
The ceramic plate-like body according to any one of claims 1 to 3, wherein the central region includes one or a plurality of first regions, and the peripheral region includes a second region. The central area consists of one first area,
The ceramic plate-like body according to claim 4, wherein the first region is surrounded by the peripheral region composed of the second region. The pore diameter of the first region is 30 μm or more and 500 μm or less,
The ceramic plate-like body according to any one of claims 1 to 5, wherein the pore size of the second region is 1 µm or more and 100 µm, provided that the pore size of the second region is lower than the pore size of the first region.   The ceramic plate-like body according to any one of claims 1 to 6, wherein a portion of the porous body is composed of open pores.   The ceramic plate-like body according to any one of claims 1 to 7, which is used as a setter for firing ceramic products. It is a manufacturing method of the ceramic plate-like object according to claim 1,
Supplying slurry containing ceramic raw material powder and gelling agent into casting mold,
Gelating the slurry to form a molded body,
The bottom of the casting mold is cooled to freeze the molded body to obtain a frozen body in which ice crystals grow from the bottom to the top of the molded body,
Drying the frozen body, removing the ice in the frozen body to obtain a dried body,
Next, subjecting the dried body to firing,
The bottom of the casting mold has two heat transfer sites with different heat transfer rates, and the size of ice crystals formed on the molded body according to the difference in heat transfer rate from the bottom to the molded body The manufacturing method of the ceramic plate-shaped object which varied. The bottom of the casting mold has a first heat transfer region having a first heat transfer rate and a second heat transfer region having a heat transfer rate higher than the first heat transfer rate;
The first heat transfer region is located in a central region of the bottom portion, and the second heat transfer region is located in a peripheral region that surrounds the central region and includes a peripheral edge of the bottom portion. Item 10. The manufacturing method according to Item 9.