JP6196748B2 - Setter for firing ceramic products - Google Patents

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,
A first region having a first porosity when viewed in plan, and a second region having a second porosity that is lower than the first porosity;
The first region and the second region provide a ceramic plate that is the same ceramic material.

The present invention also provides a method for producing the ceramic plate-like body as described above.
Placing the nesting member in the concave portion of the casting mold having a concave portion complementary to the target ceramic plate,
In the recess, a first slurry containing a ceramic raw material powder and a gelling agent is supplied and gelled to form a first molded body,
Supplying the second slurry containing the ceramic raw material powder and the gelling agent to the demolding space generated by demolding the nested member from the recess and then demolding the nested member;
Freezing the first molded body and the second slurry supplied to the demolding space of the first molded body to obtain a frozen body,
The frozen body is dried to obtain a dried body,
And then subjecting the dried body to firing,
The present invention provides a method for producing a ceramic plate-like body using the first and second slurries having different concentrations of the ceramic raw material powder contained therein.

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 preferred method for producing the ceramic plate-like body shown in FIG. 4 (a) to 4 (d) are process diagrams showing a preferred method for manufacturing the ceramic plate-like body shown in FIG. 1, following FIG. 3 (c). FIG. 5 is a scanning electron microscope image of the central region of the ceramic plate obtained in Example 1. 6 is a scanning electron microscope image of the peripheral area of the ceramic plate obtained in Example 1. FIG. FIG. 7 is a thermographic image when the ceramic plate obtained in Example 1 is heated and then rapidly cooled. FIG. 8 is a thermographic image when the ceramic plate obtained in Comparative Example 2 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. 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, and the main body 11 has two regions having different porosity. Specifically, the main body 11 has a first region 21 having a first porosity when viewed in plan and a second region having a second porosity that is lower than the first porosity. Area 22. When the first region 21 and the second region 22 are formed by a method described later, the porosity in the first region 21 and the porosity in the second region 22 change in a step shape. However, the boundary between the first region 21 and the second region 22 may not be clear, and the porosity may gradually decrease from the first region 21 to the second region 22. When the porosity gradually decreases from the first region 21 to the second region 22, the boundary between the two regions is a portion having an average value of the porosity of the first region 21 and the porosity of the second region. The first region 21 and the second region 22 are preferably integrally formed. “Integrally formed” means that the first region 21 and the second region 22 are not joined by any joining means, but the two regions 21 and 22 are continuous structures as ceramics. It means being. According to a preferred manufacturing method described later, the ceramic plate 10 in which the first region 21 and the second region 22 are integrally formed can be manufactured. However, when another manufacturing method is employed, In some cases, the ceramic plate 10 in which the regions 21 and 22 are not integrally formed may be obtained. When the first region 21 and the second region 22 are integrally formed, when the ceramic plate 10 is heated and / or cooled, the temperature difference between the central region and the peripheral region of the main body 10 is further increased. Since it can be made small, it is preferable.

The main body 11 has a central area in a plan view and a peripheral area that surrounds the central area and includes the peripheral edge of the main body 11, and the central area is from one first area 21. It has become. The peripheral area is composed of the second area 22. The first region 21 located in the central region has a rectangular shape that is substantially similar to the shape of the main body 11 in a plan view of the main body 11. 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 and the second region 22 is a ring having the same inner diameter as the circle, and the circle of the first region 21 and the ring of the second region 22 are concentric. It is preferable. 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.

  It is preferable that the 1st area | region 21 has a fixed porosity, ie, 1st porosity, in the whole area of the thickness direction and in-plane direction. On the other hand, it is preferable that the 2nd area | region 22 has a fixed porosity, ie, a 2nd porosity, throughout the thickness direction and the in-plane direction.

  The first region 21 and the second region 22 are made of the same ceramic material. Since both the regions 21 and 22 are made of the same ceramic material, the sense of unity between both the regions 21 and 22 is enhanced, which is advantageous in terms of maintaining strength and heat conduction. In particular, when both the regions 21 and 22 are integrally formed as described above, the sense of unity is further enhanced if both the regions 21 and 22 are made of the same ceramic material. 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 that the first region 21 that is a high porosity region has a smaller heat capacity than the second region 22 that is a low porosity region. By arranging the second region 22 having a large heat capacity in the peripheral region surrounding the central region, the central region which is difficult to be heated can be easily heated during heating, while the central region which is difficult to be cooled is easily heated during cooling. This is because the temperature difference between the central region and the peripheral region during heating and cooling can be reduced as a result.

  In particular, as illustrated in Examples 1 and 2 to be 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 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 70% or more and 90%. % Or less is more preferable. 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 0% or more and 70% or less, and more preferably 0% or more and 60% or less. More preferably, it is 0% or more and 50% or less.

  The porosity is a physical property value defined by the apparent porosity measured by the Archimedes method. The porosity of the first region 21 and the second region 22 of the main body 11 is measured by the following method. The main body 11 is processed with a cutter, and only the first region 21 and the second region 22 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, the area S _T of the main body portion 11 in a plan view On the other hand, it is preferably 20% or more and 95% or less, more preferably 40% or more and 85% or less, and further preferably 50% or more and 70% or less. From the same viewpoint, the proportion of the area S2 of the second region 22 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, 60% less than 15% More preferably, it is 30% or more and 50% 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. You may form in the center area of the main-body part 11. FIG. In this case, two or more first regions 21 are partitioned by a third region (not shown). The third region has a lower porosity than the first region 21, but has a higher porosity than the second region 22. The third region may partition the first region 21 and the second region 22 in addition to partitioning between the adjacent first regions 21.

  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. First, as shown in FIG. 3A, a casting mold 30 is prepared. The casting mold 30 has a bottom surface 31 that is substantially rectangular in plan view, and four side surfaces 32 that stand up 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.

  A core member 33 is placed on the bottom surface 31 in the recess S of the casting mold 30 as shown in FIG. The core member 33 has a rectangular parallelepiped shape. The core member 33 has the same shape as that of the first region 21 in the target ceramic plate 10 in plan view. The mounting position of the core member 33 on the bottom surface 31 is made to coincide with the intended formation region of the first region 21 in the target ceramic plate 10.

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

The ceramic raw material powder contained in the first slurry 41 is a raw material for the ceramic material constituting the second region 22 in 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 first slurry 41 is related to the porosity of the second region 22 in the target ceramic plate 10. Specifically, the higher the concentration of the ceramic raw material powder contained in the first slurry, the lower the porosity of the second region 22. From this viewpoint, the concentration of the ceramic raw material powder contained in the first slurry 41 is preferably 17 parts by volume or more and 150 parts by volume or less, and 25 parts by volume or more and 150 parts by volume or less with respect to 100 parts by volume of the medium. More preferably, it is 33 volume parts or more and 150 volume parts or less.

  The type and concentration of the gelling agent contained in the first slurry 41 are related to the degree of gelation of the first slurry 41 described later. From this viewpoint, the concentration of the gelling agent contained in the first 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 with respect to 100 parts by mass of the medium. More preferably, it is 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 freeze-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.

  You may mix | blend another component with the 1st slurry in addition to the component mentioned above. 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 first slurry 41 is supplied into the recess S of the casting mold 30, the slurry is gelled. In order to gelate, for example, the slurry 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 first slurry, the slurry acquires shape retention and the first molded body 41a is obtained.

  Next, as shown in FIG. 4A, the core member 33 surrounded by the first molded body 41a is removed. Since the first molded body 41a has shape retention as described above, the shape of the first molded body 41a does not change even if the core member 33 is removed. As a result, a demolding space 43 is formed in the central region of the first molded body 41a by demolding. The demolding space 43 is a through hole, and the bottom surface 31 of the casting mold 30 is exposed at the bottom.

  As shown in FIG. 4B, the second slurry 42 is supplied to the demolding space 43 formed by demolding the core member 33. The second slurry 42 contains ceramic raw material powder and a gelling agent as a medium. The second slurry 42 contains water or a water-soluble organic solvent as a medium.

The ceramic raw material powder contained in the second slurry 42 is a raw material for the ceramic material constituting the first region 21 in the target ceramic plate 10. This ceramic raw material powder is the same type as the ceramic raw material powder contained in the first slurry 41. The particle diameter of the ceramic raw material powder contained in the second slurry 42 may be the same as or different from the particle diameter of the ceramic raw material powder contained in the first slurry 41. The particle diameter of the ceramic raw material powder contained in the second slurry 42 is 0.1 μm or more and 100 μm or less in terms of a volume cumulative particle diameter D ₅₀ at a cumulative volume of 50% by volume measured by a laser diffraction / scattering particle size distribution measurement method. Preferably, it is 0.05 μm or more and 10 μm or less, and more preferably 0.1 μm or more and 1 μm or less.

  The concentration of the ceramic raw material powder contained in the second slurry 42 is related to the porosity of the first region 21 in the target ceramic plate 10. Specifically, the porosity of the first region 21 increases as the concentration of the ceramic raw material powder contained in the second slurry 42 decreases. In the ceramic plate 10 that is the object of this manufacturing method, since the porosity is different between the first region 21 and the second region 22, the concentration of the ceramic raw material powder contained in the second slurry 42 and By making the concentration of the ceramic raw material powder contained in the first slurry 41 different from each other, the intended first region 21 and second region 22 can be successfully formed. From this point of view, 1 part by volume with respect to 100 parts by volume of the medium is provided on the condition that the concentration of the ceramic raw material powder contained in the second slurry 42 is lower than the concentration of the ceramic raw material powder contained in the first slurry 41. It is preferably 33 parts by volume or less, more preferably 1 part by volume or more and 25 parts by volume or less, and still more preferably 1 part by volume or more and 18 parts by volume or less.

  The gelling agent contained in the second slurry 42 may be the same as or different from the gelling agent contained in the first slurry 41. The concentration of the gelling agent contained in the second slurry 42 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, the amount is 1 part by mass or more and 4 parts by mass or less.

  The amount of the second slurry 42 supplied into the demolding space 43 is preferably such that the liquid level of the second slurry 42 is at the same position as the upper surface of the first molded body 41a. By doing in this way, the 1st surface 11a of the main-body part 11 in the ceramic plate-like body 10 obtained can be made into a flat surface.

  These are subjected to a freezing step in a state in which the second slurry 42 is filled in the demolding space 43 of the first molded body 41a. Prior to this, the second slurry 42 may be gelled by cooling, or may be subjected to a lyophilization step without being gelled. By subjecting to the freezing step, freezing proceeds from one direction, ice crystals grow, and an oriented structure of the ceramic raw material powder in the first compact body 41a and the second slurry 42 is formed. That is, rearrangement of the ceramic raw material powder occurs. A known cooling device can be used for freezing. Specifically, a method of bringing the lower surface of the casting mold 30 into contact with a solid such as a cooled metal plate, a method of immersing the casting mold 30 together in 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 or immersed in 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. and freeze in one direction from the bottom using the ethanol type freezer described above.

  Next, the frozen body generated by freezing is taken out from the casting mold 30 and dried as shown in FIG. 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 44 generated 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 porosity of the central region of the plate-shaped main body 11 is set higher than the porosity of the peripheral region, but the first region 21 with a high porosity and the second region 22 with a low porosity 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 high porosity is arranged in the peripheral region of the plate-like body, and the second region 22 having a low porosity is arranged in the center of the plate-like body. It can also be placed in the area. Or the 1st area | region 21 with a high porosity and the 2nd area | region 22 with a low porosity may be arrange | positioned alternately at stripe form, or may be arrange | positioned at checkered pattern shape.

  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 from this, an aqueous solution in which gelatin as a gelling agent is dissolved in hot water is prepared, and both are mixed to form the first A slurry 41 was obtained. First slurry 41 obtained in this manner comprises alumina particles D ₅₀ is 0.5 [mu] m, a water slurry further containing gelatin and a dispersing agent. The composition of this slurry is shown in Table 1 below. The amount of alumina particles relative to 100 parts by volume of water in the slurry was 43 parts by volume.

On the other hand, 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. 2 slurry 42 was obtained. Second slurry 42 obtained in this manner comprises alumina particles D ₅₀ is 0.5 [mu] m, a water slurry further containing gelatin and a dispersing agent. The composition of this slurry is shown in Table 1 below. The amount of alumina particles relative to 100 parts by volume of water in the slurry was 11 parts by volume.

  A casting mold 30 having a square shape in plan view was used. The dimension of the casting mold 30 in plan view was 130 mm × 130 mm. A rectangular parallelepiped core member 33 is arranged in the central region of the concave portion S of the casting mold 30, and the first slurry 41 is supplied under this state. The core member 33 had a rectangular shape of 96.4 mm × 96.4 mm in plan view. The supply amount of the first 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 first slurry 41 was cooled and gelled to obtain a first molded body 41a.

  Next, the core member 33 was demolded, and the second slurry 42 was supplied into the demolding space 43 generated by the demolding. The supply amount of the second slurry 42 was set such that the upper surface of the first molded body 41a and the liquid surface of the second slurry 42 coincided. Under this condition, the casting mold 30 was frozen at −10 ° C. using ethanol. The obtained frozen body 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 Instrument Co., Ltd.).

The dried body thus obtained was calcined at 1600 ° C. for 7 hours in the air. 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. In the ceramic plate-like body 10, the porosity of the central region of the main body 11 was 80%, and the porosity of the peripheral region was 25%. The main body 11 was composed of a first region 21 and a second region 22. The proportion of the sum S1 of the area of the first region 21 to the area S _T of the main body portion 11 in plan view are as shown in Table 2. FIG. 5 shows a scanning electron micrograph of the central region of the ceramic plate of Example 1, and FIG. 6 shows a scanning electron micrograph of the peripheral region of the ceramic plate of Example 1. Comparison of these scanning electron micrographs also shows that the central region has more voids than the peripheral region, and has a higher porosity than the peripheral region.

[Example 2]
In Example 1, the core member 33 having a rectangular shape of 111.7 mm × 111.7 mm in plan view was used. Except for this, a ceramic plate 10 was obtained in the same manner as in Example 1. The main body 11 was composed of a first region 21 and a second region 22. The proportion of the sum S1 of the area of the first region 21 to the area S _T of the main body portion 11 in plan view are as shown in Table 2.

Example 3
In Example 1, the first and second slurries having the compositions shown in Table 1 below were used. Further, the core member 33 having a rectangular shape of 124.5 mm × 124.5 mm in plan view was used. Except for this, a ceramic plate 10 was obtained in the same manner as in Example 1. The main body 11 was composed of a first region 21 and a second region 22. The proportion of the sum S1 of the area of the first region 21 to the area S _T of the main body portion 11 in plan view are as shown in Table 2. The amount of alumina particles relative to 100 parts by volume of water in the first slurry was 25 parts by volume. The amount of alumina particles relative to 100 parts by volume of water in the second slurry was 11 parts by volume.

[Comparative Example 1]
In Example 1, only the second slurry 42 was used, and the core member 33 was not used. A ceramic plate was obtained in the same manner as in Example 1 except for this. The porosity of the main body 11 in this ceramic plate was 80%.

[Comparative Example 2]
A mixture was obtained by mixing 40 parts of electrofused alumina, 30 parts of electrofused mullite, 30 parts of calcined alumina, an appropriate amount of an organic binder, and a liquid binder. This mixture was kneaded, dried, and press molded to obtain a molded body. This molded body was fired in the atmosphere at 1750 ° C. to obtain a refractory plate-like body. The porosity of the main body 11 in this refractory plate was 17%. The thickness of the main body 11 was 5 mm.

[Evaluation]
The ceramic plate obtained in Examples and Comparative Examples was 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. 7, and what was image | photographed about the comparative example 2 is shown in FIG. 8 as an external appearance photograph which colored the measured temperature distribution by thermography.

  As is apparent from the results shown in Table 2, the ceramic plate 10 obtained in Example 1 was a ceramic plate of the comparative example because the porosity was different between the central region and the peripheral region. It can be seen that the temperature difference between the central region and the peripheral region is smaller than that in FIG. Moreover, it turns out that it cools in a short time. In particular, in Examples 1 and 2, the temperature in the central region is lower than that in the peripheral region, and when the object to be fired is placed in the central region and fired, the peripheral region and the central region It can be seen that the amount of heat is easily offset. Further, as apparent from the comparison between FIG. 7 and FIG. 8, in Comparative Example 2 in FIG. 8, 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.

  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 porosity of a part of the plate-like body is compared with other parts. The advantage resulting from the higher or lower height 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.

Claims (5)

It has a plate-shaped porous body made of ceramics,
The plate-like porous body has a first region having a first porosity when viewed in plan, and a second porosity having a second porosity that is lower than the first porosity. And having an area of
The first region and the second region are the same ceramic material,
The plate-like porous body portion has 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 porous body part.
The central area consists of one first area, the peripheral area consists of a second area,
The ratio of the total area of the first regions in plan view is 50 % or more and 95% or less with respect to the area of the plate-like porous body portion,
The ratio of the area of the second region in plan view state, and are 5% to 50% relative to the area of the portion of the plate-shaped porous body,
The porosity of the first region is 50% or more and 99% or less,
The porosity of the second region, a condition that is lower than the porosity of the first region, 40% to 70% der Ru firing setter for ceramic products. The setter for firing a ceramic product according to claim 1, wherein the first region and the second region are integrally formed. 3. The setter for firing a ceramic product according to claim 1, wherein the first region is substantially similar to the shape of the plate-like porous body portion in a plan view of the plate-like porous body portion. . Of the lengths until the normal line drawn at an arbitrary position on the peripheral edge of the first region in plan view intersects with the peripheral edge of the plate-like porous body portion, the longest with respect to the shortest length L _min The setter for firing a ceramic product according to any one of claims 1 to 3, wherein a value of L _max / L _min which is a ratio of the length L _max is 8 or less . It has a plate-shaped porous body made of ceramics,
A first region having a first porosity when viewed in plan, and a second region having a second porosity that is lower than the first porosity;
The first region and the second region are a method for producing a ceramic plate that is the same ceramic material,
Placing the nesting member in the concave portion of the casting mold having a concave portion complementary to the target ceramic plate,
In the recess, a first slurry containing a ceramic raw material powder and a gelling agent is supplied and gelled to form a first molded body,
Supplying the second slurry containing the ceramic raw material powder and the gelling agent to the demolding space generated by demolding the nested member from the recess and then demolding the nested member;
Freezing the first molded body and the second slurry supplied to the demolding space of the first molded body to obtain a frozen body,
The frozen body is dried to obtain a dried body,
And then subjecting the dried body to firing,
The manufacturing method of the ceramic plate-shaped object using what the density | concentrations of the said ceramic raw material powder contained in them differ from each other as 1st and 2nd slurry.