JP2013209238A - Method for manufacturing ceramic sheet, and laminated structure used for manufacturing ceramic sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a ceramic sheet at excellent yield, especially an electrolyte sheet for a solid oxide-type fuel cell.SOLUTION: A method for manufacturing a ceramic sheet includes (I) a step of manufacturing a laminated structure including a setter 1 and a sheet laminate 2 by placing the sheet laminate 2 including a ceramic green sheet on the setter 1, and (II) a step of firing the ceramic green sheet in the state of the laminated structure. The setter 1 includes a rectangular placing region 16 where the sheet laminate 2 can be placed. In the laminated structure, a visible outline A appearing when the sheet laminate 2 is projected on a virtual plane vertical to the stacking direction of setter 1 and sheet laminate 2 is positioned on the furthermore inside than a visible outline B appearing when a placing region 12 of the setter 1 is projected on the virtual plane, and the shortest distance d from each side forming the visible outline B to the visible outline A is ≤3.0 mm, respectively.

Description

  The present invention relates to a method for producing a ceramic sheet and a laminated structure used for producing a ceramic sheet.

  Ceramic sheets have excellent mechanical strength, electrical insulation, toughness, wear resistance, chemical resistance, corrosion resistance, etc., so they are used for various electronic materials, various structural materials, blades, firing setters, etc. Has been. Among them, ceramic sheets mainly composed of alumina have excellent electrical insulation, so that ceramic sheets mainly composed of aluminum nitride have excellent thermal conductivity and insulation as thick film printed boards and thin film circuit boards. Therefore, the ceramic sheet mainly composed of zirconia is utilized as an electrolyte membrane of a fuel cell because it has high oxygen ion conductivity.

  When a ceramic sheet is used as an electronic substrate, a conductor circuit is formed on the substrate or an electronic element is mounted. Therefore, the ceramic sheet serving as the substrate is warped or undulated, and has surface defects such as scratches. As a result, it becomes difficult to mount a conductor circuit or an electronic element.

  In recent years, fuel cells have attracted attention as clean energy sources. Among fuel cells, a solid oxide fuel cell (hereinafter referred to as SOFC) that uses a solid ceramic as an electrolyte can use exhaust heat because of its high operating temperature, and obtains electric power with higher efficiency. It is expected to be used in a wide range of fields from household power sources to large-scale power generation.

  The SOFC cell has a basic structure in which an electrolyte made of ceramic is disposed between a cathode (air electrode) and an anode (fuel electrode). For example, a flat SOFC has a single cell in which a cathode, an electrolyte sheet, and an anode are stacked. High output can be obtained by stacking a plurality of the single cells with the interconnector interposed therebetween. Such an electrolyte sheet is required to have high dimensional accuracy, high flatness (suppression of warpage and undulation), and the like. Therefore, establishment of a manufacturing method capable of realizing high dimensional stability, suppressing the occurrence of warpage and waviness, and suppressing the occurrence of cracks and chipping, in order to reduce the production cost of the electrolyte sheet and improve the productivity. Is required.

  For the SOFC electrolyte, zirconia-based, ceria-based, and lanthanum gallate-based ceramic materials are preferably used. Examples of the zirconia ceramic material include yttria stabilized zirconia (YSZ) and scandia stabilized zirconia (ScSZ). Examples of the ceria-based ceramic material include ceria doped with yttria, samaria and / or gadria. As lanthanum gallate ceramic materials, lanthanum gallate and a part of lanthanum gallium and / or gallium are replaced with strontium, calcium, barium, magnesium, aluminum, indium, cobalt, iron, nickel, and / or copper, etc. Can be mentioned. Therefore, a sheet made of these ceramic electrolyte materials can be manufactured with a high yield by a method that can realize high dimensional stability, suppress the occurrence of warpage and waviness, and suppress the occurrence of cracks and chips. Desired.

  A ceramic sheet is usually formed into a tape shape by a slurry obtained by mixing and pulverizing ceramic raw material powder, a binder, a solvent and the like into a tape shape by a doctor blade method or the like, and the green tape is cut into a predetermined shape. It can be produced by firing a punched green sheet. Normally, when firing green sheets, ceramic porous spacers and green sheets are alternately stacked on the ceramic setter for the purpose of increasing productivity and achieving high flatness of the sheet. A green sheet is fired in the state of the sheet laminate (see, for example, Patent Document 1).

  The ceramic setter on which the sheet laminate is disposed includes a placement surface on which the sheet laminate is placed. For example, the setter may have a configuration in which support columns are provided in regions (for example, four corners) of the placement surface where the sheet stack is not disposed. With this support column, it is possible to stack a plurality of setters on which the sheet laminate is placed (for example, Patent Document 2).

JP 2007-302515 A JP 2011-116617 A

  However, the dimensional accuracy required for ceramic sheets, particularly electrolyte sheets for SOFC, is increasing. Therefore, in the conventional method, it has become difficult to produce a ceramic sheet satisfying such high requirements with a high yield.

  Then, an object of this invention is to provide the method which can manufacture a ceramic sheet, especially the electrolyte sheet for SOFC with a sufficient yield. Furthermore, this invention also aims at providing the laminated structure containing the ceramic green sheet used in the method.

  This inventor examined the lamination process and baking process of the green sheet for ceramic sheets, and discovered the relationship between the positional relationship between a setter and a sheet laminated body, and the yield of the ceramic sheet manufactured.

The method for producing the ceramic sheet of the present invention comprises:
(I) A step of placing a sheet laminate including a ceramic green sheet on a setter to produce a laminate structure including the setter and the sheet laminate;
(II) firing the ceramic green sheet in the state of the laminated structure;
Including
The setter includes a rectangular placement region on which the sheet laminate can be placed,
In the laminated structure, the outline A that appears when the sheet laminated body is projected onto a virtual plane perpendicular to the stacking direction of the setter and the sheet laminated body has the placement area of the setter on the virtual plane. The shortest distance from each side forming the outline B to the outline A is 3.0 mm or less, which is located inside the outline B that appears when projected.

The laminated structure of the present invention is
Setter,
A sheet laminate including a ceramic green sheet placed on the setter;
Including
The setter includes a rectangular placement region on which the sheet laminate can be placed,
The outline A that appears when the sheet laminate is projected onto a virtual plane perpendicular to the stacking direction of the setter and the sheet laminate, and the outline that appears when the placement area of the setter is projected onto the virtual plane The shortest distance from each side forming the outline B to the outline A is 3.0 mm or less.

  In the production method of the present invention, in the step of firing the ceramic green sheet, the positional relationship between the sheet laminate including the green sheet and the setter on which the sheet laminate is placed is within the specific range as described above. It is limited to. By satisfying such a positional relationship, the ceramic sheet can be manufactured with a high yield. Moreover, by using the laminated structure of the present invention, it becomes possible to produce a ceramic sheet with a high yield.

(A) is a top view of the setter used in process (I) of the manufacturing method of this invention, (b) is the II sectional view taken on the line of (a). It is a top view which shows the laminated structure comprised by the setter used in the process (I) of the manufacturing method of this invention, and the sheet | seat laminated body containing the ceramic green sheet mounted on the said setter. It is a top view which shows the laminated structure comprised by the setter used by the comparative example 1, and the sheet laminated body containing the ceramic green sheet mounted on the said setter.

  Hereinafter, embodiments of the present invention will be specifically described.

The method for producing the ceramic sheet of the present embodiment is as follows:
(I) A step of placing a sheet laminate including a ceramic green sheet on a setter to produce a laminate structure including the setter and the sheet laminate;
(II) firing the ceramic green sheet in the state of the laminated structure;
including.

  First, the ceramic green sheet used in step (I) will be described by taking as an example a green sheet for an electrolyte sheet for SOFC. The green sheet for the electrolyte sheet for SOFC used in the manufacturing method of the present embodiment includes, for example, a binder and a solvent added to the ceramic electrolyte raw material powder, and further, a dispersant, a plasticizer, and a lubricant as necessary. And an antifoaming agent or the like is added to prepare a slurry, and the green tape obtained by forming the slurry into a tape shape and drying it is cut and punched into a predetermined shape.

Examples of the ceramic electrolyte raw material powder include alkaline earth metal oxides such as MgO, CaO, SrO and BaO; Sc ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , CeO ₂ , Pr ₂ O ₃ , Nd ₂ O ₃ , rare earth element oxides such as Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ and Yb ₂ O ₃ ; Examples thereof include zirconia powder containing one or more selected from oxides such as Bi ₂ O ₃ and In ₂ O ₃ as a stabilizer. Further, as other additives, any oxide selected from SiO ₂ , Ge ₂ O ₃ , B ₂ O ₃ , SnO ₂ , Ta ₂ O ₅ and Nb ₂ O ₅ may be contained. Among these, in order to ensure a higher level of oxygen ion conductivity, strength and toughness, at least one selected from the group consisting of scandia, yttria, ceria and ytterbia is included as a stabilizer. , Stabilized zirconia. The content of the stabilizer in the entire stabilized zirconia is 4 to 12 mol% for scandia, 3 to 10 mol% for yttria, 0.5 to 2 mol% for ceria, and 4 to 15 mol% for ytterbia. The crystal system may be a tetragonal system or a cubic system, but in the case of zirconia containing scandia, if the scandia content increases, the crystal system may transition to rhombohedral crystals. In order to stabilize the crystal system into a cubic system, ceria and / or alumina may be added as a third component. Hereinafter, for example, zirconia stabilized with 4 mol% of scandia (meaning “zirconia containing 4 mol% of scandia as a stabilizer”. Hereinafter, the same expression is used in the same sense.) 4ScSZ, 10 Zirconia stabilized with mol% scandia and 1 mol% ceria is denoted as 10Sc1CeSZ, and zirconia stabilized with 8 mol% yttria is denoted as 8YSZ.

  As the ceramic electrolyte raw material powder, ceria-based ceramic material powder and lanthanum gallate-based ceramic material powder can also be used. Examples of the ceria-based ceramic material include ceria doped with yttria, samaria and / or gadria. As lanthanum gallate ceramic materials, lanthanum gallate and a part of lanthanum gallium and / or gallium are replaced with strontium, calcium, barium, magnesium, aluminum, indium, cobalt, iron, nickel, and / or copper, etc. Can be mentioned.

  The green sheet for the SOFC electrolyte sheet used in the present embodiment is produced using the ceramic electrolyte raw material powder as described above.

  The ceramic powder that is the main material of the ceramic sheet other than the electrolyte sheet for SOFC includes alumina powder, titania powder, magnesia powder, aluminum nitride powder, borosilicate glass powder, cordierite powder, mullite. And a composite powder composed of two or more of these. In addition, zirconia powder, ceria powder, and lanthanum gallate powder can be used as the ceramic powder.

An alumina-based powder is particularly desirable as a material for a ceramic sheet for an electronic substrate for forming a circuit or mounting an electronic element, and an aluminum nitride-based powder is particularly desirable as a heat dissipation / insulating substrate. Examples of the alumina-based powder include alumina alone, oxides of alkaline earth metals such as MgO, CaO, SrO and BaO, oxides of rare earth elements such as Y ₂ O ₃ , La ₂ O ₃ and CeO ₂ , Y ₂ Zirconia stabilized with oxides of rare earth elements such as O ₃ , La ₂ O ₃ and CeO ₂ , oxides such as SiO ₂ , K ₂ O and B ₂ O ₃ that easily form glass during sintering, Na Examples thereof include powders made of alumina ceramics containing one or more glass components such as ₂ O ₃ —SiO ₂ —MgO glass. Examples of the aluminum nitride powder include only aluminum nitride, oxides of alkaline earth metals such as MgO, CaO, SrO and BaO, oxides of rare earth elements such as Y ₂ O ₃ , La ₂ O ₃ and CeO ₂ May be a powder made of an aluminum nitride-based ceramic containing one kind or two or more kinds.

  There is no restriction | limiting in the kind of binder used for preparation of a green sheet, It can select suitably from the organic binders well-known with the manufacturing method of the conventional electrolyte sheet. Organic binders include ethylene copolymers, styrene copolymers, acrylate and methacrylate copolymers, vinyl acetate copolymers, maleic acid copolymers, vinyl acetal resins, vinyl formal resins, polyvinyl Examples include butyral resin, vinyl alcohol resin, celluloses such as ethyl cellulose, and waxes. Among these, green acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, cyclohexyl acrylate, 2-ethylhexyl from the viewpoint of green sheet moldability and strength, especially thermal decomposability when mass-baking for mass production. Alkyl acrylates having an alkyl group having 10 or less carbon atoms such as acrylates; 20 or less carbon atoms such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, lauryl methacrylate Alkyl methacrylates having various alkyl groups; hydroxyethyl acrylate, hydroxypropyl acetate Hydroxyalkyl acrylates or hydroxyalkyl methacrylates having a hydroxyalkyl group such as rate, hydroxyethyl methacrylate, hydroxypropyl methacrylate; aminoalkyl acrylates or aminoalkyl methacrylates such as dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate; (meth) acrylic acid A polymer obtained by polymerizing or copolymerizing at least one of monomers containing a carboxyl group such as maleic acid half ester such as maleic acid and monoisopropylmalate is preferably used.

  There is no restriction | limiting in the kind of solvent used for preparation of a green sheet, It can select suitably from the solvents well-known with the manufacturing method of the conventional electrolyte sheet. For example, alkyl alcohols having 2 to 4 carbon atoms such as ethanol, isopropanol and n-butanol; alcohols such as 1-hexanol; ketones such as acetone and 2-butanone; aliphatic hydrocarbons such as pentane, hexane and heptane Solvents appropriately selected from: aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene; acetic esters such as methyl acetate, ethyl acetate and butyl acetate can be used. These solvents may be used alone or in combination of two or more.

  Dispersants, plasticizers, lubricants and antifoaming agents used as necessary include known dispersants, plasticizers, lubricants and antifoaming agents used in the production of electrolyte sheets by conventional production methods. , Can be used respectively.

  A slurry prepared by mixing ceramic raw material powder, binder, solvent, etc., is formed into a tape shape by a usual method, for example, a doctor blade method, an extrusion molding method or a calender roll method, etc. The green sheet for ceramic sheets is producible by cut | disconnecting to the shape of this. In addition, the process of roughening the surface of a green sheet may be included as needed. The size and thickness of the green sheet are determined from the shape, size and thickness of the target ceramic sheet and the shrinkage rate due to firing.

In the case of an electrolyte sheet for SOFC, the green sheet used in the manufacturing method of the present embodiment is such that the finally obtained electrolyte sheet has an area of 50 to 1000 cm ² and 0.05 to 0.5 mm. It is desirable to have a size and thickness, such as having a thickness.

  The shape of the green sheet is not particularly limited because it may be appropriately determined according to the use, for example, in the case of an electrolyte sheet, according to the shape of the SOFC to which the electrolyte sheet is applied.

  A sheet laminate including a green sheet is disposed on the setter. The sheet laminate can be formed, for example, by superposing a plurality of green sheets on each other via a ceramic porous spacer. For example, a sheet laminate comprising a ceramic porous spacer and a green sheet, in which green sheets and ceramic porous spacers are alternately stacked so that ceramic porous spacers are disposed on the lowermost layer and the uppermost layer on the setter. Place.

  In the sheet laminate, the green sheet and the ceramic porous spacer may be arranged as follows when the ceramic porous spacer has a rectangular or circular shape, for example.

  First, an example of the positional relationship between the ceramic porous spacer and the green sheet will be described in the case where the ceramic porous spacer has a rectangular shape. Let X be the shortest distance from any point A on the outer edge of the ceramic porous spacer to the outer edge of the green sheet. When the point A is located on the long side of the ceramic porous spacer, the length of the short side is Y, and when the point A is located on the short side of the ceramic porous spacer, the length of the long side is Y. To do. At this time, the ceramic porous spacer and the green sheet may be arranged so that X and Y satisfy (X / Y) × 100 = 0.2 to 4.0. By setting the value of (X / Y) × 100 in such a range, the yield of the ceramic sheet can be improved. The ceramic porous spacer and the green sheet are desirably arranged so that X and Y satisfy (X / Y) × 100 = 0.3 to 3.5, and satisfy 0.4 to 3.0. It is more desirable to be arranged in

  An example of the positional relationship between the ceramic porous spacer and the green sheet will be described in the case where the ceramic porous spacer has a circular shape. Let X be the shortest distance from any point A on the outer edge of the ceramic porous spacer to the outer edge of the green sheet. Let Y be the diameter of the ceramic porous spacer. Also in this case, the ceramic porous spacer and the green sheet may be arranged so that X and Y satisfy (X / Y) × 100 = 0.2 to 4.0. By setting the value of (X / Y) × 100 in such a range, the yield of the ceramic sheet can be improved. The ceramic porous spacer and the green sheet are desirably arranged so that X and Y satisfy (X / Y) × 100 = 0.3 to 3.5, and satisfy 0.4 to 3.0. It is more desirable to be arranged in

  The number of green sheets to be stacked is, for example, 2 to 20 sheets, preferably 4 to 12 sheets, depending on the dimensions.

  The ceramic porous spacer used in the manufacturing method of the present embodiment is preferably made of a porous body containing at least one selected from the group consisting of alumina, zirconia, and mullite. This is because these are excellent in creep resistance and spalling resistance. Furthermore, since these have low reactivity with zirconia in a high temperature atmosphere, they are suitable as spacers when firing zirconia green sheets.

  The porosity of the ceramic porous spacer is preferably 30% or more and 70% or less. When the ceramic porous spacer has such a porosity, when the green sheet is fired in a state where the ceramic porous spacer and the green sheet are alternately stacked, the organic porous component such as a binder, a plasticizer, and a dispersing agent This is because the degreasing effect can be promoted by quickly releasing the gas component generated by the thermal decomposition to the outside. When a porous spacer having a porosity of less than 30% is used, combustion of organic components and release of organic component decomposition gas become insufficient due to a decrease in air permeability, and even if a weight is placed on the laminate, the electrolyte The height of waviness and warpage generated in the sheet is large and large, which causes cracks and cracks. On the other hand, when a porous spacer having a porosity of more than 70% is used, combustion of the organic component and efficient release of the organic component decomposition gas are performed to reduce the occurrence of swell and warp. Since the strength is insufficient, the handling property is remarkably lowered and it cannot be used multiple times, and the smoothness of the surface of the porous spacer is also deteriorated so that the electrolyte sheet is likely to be cracked or cracked. Arise. The more desirable porosity of the porous spacer is 35% or more and 65% or less, and the more desirable porosity is 40% or more and 60% or less.

In addition, the porosity here is the porosity calculated | required based on "The measuring method of the apparent porosity of a refractory brick" of JISR2205. The apparent porosity (P ₀ ) of the sample is expressed by the following formula (1) from the mass of the dry sample (W ₁ ), the mass of the saturated sample in water (W ₂ ), and the mass of the saturated sample (W ₃ ). Calculated.
P ₀ = {(W ₃ −W ₁ ) / (W ₃ −W ₂ )} × 100 (1)

  In addition, when the thickness of the porous spacer is less than 100 μm, the handling strength of the porous spacer itself is not sufficient even if the porosity is within the above desired range. On the other hand, when the thickness exceeds 500 μm, the handling strength is Although sufficient, the organic component decomposition gas from the green sheet is less likely to be efficiently diffused, and undulation and warpage tend to occur in the electrolyte sheet. A more desirable thickness of the porous spacer is 120 μm or more and 400 μm or less, and a more desirable thickness is 150 μm or more and 350 μm or less.

  The area and shape of the porous spacer are determined based on the area and shape of the green sheet specified from the area and shape of the target electrolyte sheet. Accordingly, the shape of the porous spacer is preferably similar to the shape of the green sheet to be fired, and may be any of a circular shape, an elliptical shape, a square shape, a square shape having R (R), and the like. It may have a hole such as a circle, an ellipse, a square, or a square having R (R).

  The setter used in the manufacturing method of the present embodiment is generally a ceramic firing jig mainly used for firing electronic parts and glass, and is also called a shelf board or a floor board. FIG. 1A shows a top view of an example of a setter. FIG.1 (b) shows the II sectional view taken on the line of Fig.1 (a). As shown in FIGS. 1A and 1B, the setter 1 has a placement surface 11 on which the sheet laminate is placed. A support column 12 is provided at the peripheral end of the mounting surface 11. The support column 12 is used to stack a plurality of setters 1 on each other. On the upper surface of the support column 12, there is a concave engaging portion 14 that mates with a convex engaging portion 13 formed on the back surface (surface opposite to the mounting surface 11) 15 of another setter 1 to be stacked. Is formed. A plurality of setters 1 can be stacked by fitting the engaging portion 13 of the setter 1 arranged in the upper stage to the engaging portion 14 of the setter 1 arranged in the lower stage. The placement surface 11 includes a rectangular placement region 16 on which the sheet laminate can be placed. In the case of the setter 1, a rectangular area that avoids the area where the support column 12 is disposed in the placement surface 11 is the placement area 16.

  FIG. 2 shows a top view of a state in which the sheet laminate 2 is arranged on the setter 1 (laminated structure). In the sheet laminate 2, the outline A that appears when the sheet laminate 2 is projected onto a virtual plane perpendicular to the stacking direction of the setter 1 and the sheet laminate 2 has the placement area 16 of the setter 1 on the virtual plane. It is located inside the outline B that appears when projected. Further, the shortest distance d from each side forming the outline B to the outline A is 3.0 mm or less. The top view shown in FIG. 2 has shown the state seen from the stacking direction of the setter 1 and the sheet | seat laminated body 2. FIG. That is, the relationship between the outline A of the sheet laminate 2 projected onto the virtual plane and the outline B of the placement area 16 of the setter 1 is such that the periphery of the sheet laminate 2 and the setter 1 shown in FIG. This is the same as the relationship with the periphery of the placement area 16. In the present embodiment, the shortest distance d from each side forming the outline B to the outline A is 3.0 mm or less, preferably 2.0 mm or less, more preferably 1.5 mm or less. . By firing the green sheet in a state where the sheet laminate 2 and the placement region 16 of the setter 1 satisfy such a relationship, the yield of the ceramic sheet to be manufactured is greatly improved. This is because the sheet laminate 1 and the placement region 16 of the setter 1 satisfy such a relationship, so that the deviation of the green sheet in the sheet laminate 2 during firing is effectively suppressed. It is thought that it is one. On the other hand, the distance d only needs to exceed 0, but in order to easily place the sheet laminate 2 on the setter 1 in an appropriate state, the distance d is preferably 1.5 mm or more, and more preferably 2.0 mm or more. . By making it easy to place the sheet laminate 2 on the setter 1 in an appropriate state, the yield of the produced ceramic sheets can be further improved.

  In the present embodiment, the setter 1 on which the sheet laminate 2 is placed can be stacked in a plurality of stages. When the setter 1 is stacked in a plurality of stages, the distance between the upper surface of the sheet laminate 2 placed on the lower setter 1 and the back surface 15 of the upper setter 1 is preferably in the range of 5.0 to 25.0 mm. A range of 10.0 to 20.0 mm is more desirable. By setting the distance between the upper surface of the sheet laminate 2 placed on the lower setter 1 and the back surface 15 of the upper setter 1 within such a range, it is generated by thermal decomposition of organic components. The gas component can be quickly released to the outside.

  The shape and size of the setter 1 may be appropriately set in consideration of the shape and size of the sheet laminate 1 so that the above relationship can be satisfied. The setter 1 is preferably made of a material containing an oxide such as alumina, silica, magnesia and zirconia and / or a composite oxide such as cordierite, zircon and mullite.

  Next, the green sheet contained in the sheet laminate 2 is fired in the state of the laminated structure (step (II)). Specific firing conditions are not particularly limited. Therefore, it is possible to use a normal method for firing the green sheet. For example, in order to remove organic components such as a binder and a plasticizer from the green sheet, the treatment is performed at 150 to 600 ° C., preferably 250 to 500 ° C. for about 5 to 80 hours. Next, an electrolyte sheet is obtained by firing at 1000 to 1800 ° C., preferably 1200 to 1600 ° C. for 2 to 10 hours in an oxidizing atmosphere or a non-oxidizing atmosphere.

  In this embodiment, the electrolyte sheet has been described as an example, but it goes without saying that the method described in this embodiment can also be applied to the manufacture of other ceramic sheets.

  The ceramic sheet obtained by the manufacturing method of the present embodiment is capable of suppressing warpage, undulation abnormality, and appearance abnormality (occurrence of scratches, cracks, and chips), and satisfies strict requirements as an electrolyte sheet for SOFC, for example. That is, the manufacturing method of the present embodiment is a method capable of manufacturing a ceramic sheet with a high yield.

  In the present embodiment, the manufacturing method of the present invention has been described by taking the case where the sheet laminate is rectangular as an example, but the shape of the sheet laminate is not limited to this. Even if the sheet laminate is, for example, circular or elliptical, the same effect can be obtained by satisfying the positional relationship between the setter and the sheet laminate satisfying the conditions specified in the present invention.

  Next, the present invention will be specifically described using examples. In addition, this invention is not limited at all by the Example shown below.

Example 1
In this example, a zirconia-based electrolyte sheet was manufactured as an SOFC electrolyte sheet.

(1) Production of zirconia-based green sheet As raw material powder, 8 parts by mass of yttrium oxide stabilized zirconia powder (manufactured by Daiichi Elemental Chemical Co., Ltd., trade name “8YSZ”, d ₅₀ (median diameter): 0.4 μm) 100 parts by mass On the other hand, a binder composed of a methacrylic copolymer (number average molecular weight: 100,000, glass transition temperature: −8 ° C., solid content concentration: 50%) is 18 parts by mass in terms of solid content, and fatty acid ester as a dispersant. 2 parts by weight of a surfactant, 3 parts by weight of dibutyl phthalate as a plasticizer, and 50 parts by weight of toluene as a solvent were placed in a nylon mill charged with zirconia balls and milled for 40 hours to prepare a slurry. The obtained slurry was transferred to a jacketed round bottom cylindrical vacuum degassing vessel equipped with a bowl-shaped stirrer and having an internal volume of 50 L. While rotating the stirrer at a speed of 30 rpm, the jacket temperature was reduced to 40 ° C. (about 4 ° C.). To 21 kPa), and the viscosity at 25 ° C. was adjusted to 3 Pa · s to obtain a coating slurry. The slurry for coating is continuously coated on a polyethylene terephthalate (PET) film by a doctor blade method, and then dried at 40 ° C., 80 ° C., and 110 ° C., thereby making untreated green for a long solid electrolyte. A body (green tape) was obtained. The green tape is peeled off from the PET film and 350 KN using a 1000 KN 4-column test press machine (manufactured by Osaka Jack Mfg. Co., Ltd.) equipped with a cardboard having an average surface roughness Ra of 3.5 μm and a thickness of 0.3 mm. For 2 seconds. Thereafter, this green tape was punched with a punching die to obtain a square green sheet having a side of 133 mm. The thickness of the obtained green sheet was 0.225 mm.

(2) Preparation of Ceramic Porous Spacer A square alumina spacer having a side of about 140 mm was used as the ceramic porous spacer. This alumina spacer had a thickness of 0.28 mm and a porosity of 45%.

(3) Preparation of setter An alumina setter having the same shape as the setter 1 shown in FIGS. 1 (a) and (b) was prepared. The horizontal length of the setter 1 was 142.5 mm (internal dimension), and the vertical length was 144 mm (internal dimension). That is, the shape of the placement area 16 of the setter 1 was a rectangle of 142.5 mm × 144 mm. Moreover, the height of the support | pillar 12 was 19.5 mm.

(4) Production of Sheet Laminate 10 sheets of zirconia green sheets manufactured as described above and 11 sheets of alumina spacers were prepared. Alumina spacers and zirconia green sheets were alternately stacked so that the alumina spacers were disposed in the lower layer and the uppermost layer.

(5) Firing A ceramic porous body (weight) having a thickness of 1.6 mm was separately placed on the sheet laminate. This was placed on the setter 1 prepared in the above (3) to produce a laminated structure as shown in FIG. An outline A that appears when the sheet laminate 2 is projected onto a virtual plane perpendicular to the stacking direction of the setter 1 and the sheet laminate 2 is an outline that appears when the placement area 16 of the setter 1 is projected onto the virtual plane. It was located inside the line B. Further, among the four sides forming the outline B, the shortest distance from the horizontal side of the setter 1 to the outline A is 2 mm, and the shortest distance from the vertical side to the outline A is 1.25 mm. Met. Moreover, the distance between the upper surface of the sheet | seat laminated body 2 mounted in the lower setter 1 and the back surface 15 of the upper setter 1 was 12.57 mm (19.5 mm (height of the support | pillar 12). -6.93 mm (the thickness of the sheet laminate 2 + the thickness of the weight)). Four stacked structures prepared in this way were arranged on the same plane, and 11 layers were stacked on each of the stacked structures to prepare a total of 44 stacked structures. These were fired in a continuous tunnel firing furnace having a continuous degreasing furnace (manufactured by Shiraishi Electric Industry Co., Ltd.) at a maximum temperature of 1400 ° C. for 3 hours.

  The number of ceramic sheets obtained after firing was 440 sheets. Various inspections were performed on all these sheets. In this example, as the jig inspection, a swell inspection using a CCD inspection apparatus and a warpage jig inspection using a warpage jig were performed. The results of the swell yield and the warp yield are as shown in Table 1. Visual inspection was further performed on the ceramic sheet that passed the jig inspection. In addition, as the appearance inspection, those in which cracks (cracks) and / or chips were confirmed were prohibited. The evaluation criteria for each item of appearance inspection are as follows.

  The ratio of the number of sheets that passed any of the inspections of swell, warpage, and appearance to the number of fired sheets was calculated, and the obtained value was taken as the overall yield. The overall yield is also shown in Table 1.

(Comparative Example 1)
A ceramic sheet was produced in the same manner as in Example 1 except that the setter used and the number of stacked setters during firing were different.

  As the setter, a conventional setter in which four sheet laminates are placed on one setter was used. FIG. 3 shows the setter 101 used in this comparative example and the sheet laminate 102 disposed thereon. The setter 101 was provided with a support column 103 at the peripheral end thereof in order to stack a plurality of setters 101. The setting area 104 of the setter 101 has a rectangular shape of 290 mm × 295 mm, and the sheet laminate 102 is arranged in the setting area 104 as shown in FIG. That is, in this comparative example, the sheet laminate is formed on the virtual plane from each side forming the outline B that appears when the placement area 104 is projected onto the virtual plane perpendicular to the stacking direction of the setter 101 and the sheet laminate. The shortest distance to the outline A that appears when 102 was projected was over 3.0 mm. The setter 101 is also provided with a support on the back surface, and in the stacked state, the support 103 provided on the mounting surface of the lower setter 101 and the support provided on the back of the upper setter 101. And a column is formed. In the setter 101, the height of the support in the stacked state was 20.5 mm.

  Eight stages of setters 101 each having four sheet laminates 102 arranged thereon were stacked, and a total of 320 green sheets were fired. The firing method was the same as in Example 1. Moreover, the distance between the upper surface of the sheet | seat laminated body 102 mounted in the lower setter 101, and the back surface of the upper setter 101 was 13.57 mm (20.5 mm (height of support | pillar) -6) .93 mm (the thickness of the sheet laminate 102 + the thickness of the weight)). The obtained ceramic sheet was subjected to jig inspection and appearance inspection in the same manner as in Example 1. These results are shown in Table 1.

  As shown in Table 1, the ceramic sheet manufactured by the method (Example 1) in which the positional relationship between the setter and the sheet laminate satisfies the conditions specified in the present invention does not satisfy this condition (Comparative Example 1). Compared with the ceramic sheet manufactured by, the swell yield increased by about 10% and the overall yield also increased by 13%.

  Since the method for producing a ceramic sheet of the present invention can produce a high-quality ceramic sheet with good yield, it can be suitably used for producing an electrolyte sheet made of a particularly expensive material such as an electrolyte sheet for SOFC.

DESCRIPTION OF SYMBOLS 1 Setter 2 Sheet laminated body 11 Mounting surface 12 Support | pillar 13,14 Engagement part 15 Back surface 16 Mounting area | region

Claims (2)

(I) A step of placing a sheet laminate including a ceramic green sheet on a setter to produce a laminate structure including the setter and the sheet laminate;
(II) firing the ceramic green sheet in the state of the laminated structure;
Including
The setter includes a rectangular placement region on which the sheet laminate can be placed,
In the laminated structure, the outline A that appears when the sheet laminated body is projected onto a virtual plane perpendicular to the stacking direction of the setter and the sheet laminated body has the placement area of the setter on the virtual plane. The shortest distance from each side forming the outline B to the outline A is 3.0 mm or less, located inside the outline B that appears when projected.
Manufacturing method of ceramic sheet. Setter,
A sheet laminate including a ceramic green sheet placed on the setter;
Including
The setter includes a rectangular placement region on which the sheet laminate can be placed,
The outline A that appears when the sheet laminate is projected onto a virtual plane perpendicular to the stacking direction of the setter and the sheet laminate, and the outline that appears when the placement area of the setter is projected onto the virtual plane The shortest distance from each side forming the outline B to the outline A is 3.0 mm or less, located on the inner side of the line B.
Laminated structure.

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