JP4995411B2 - Ceramic joined body and solid oxide fuel cell using the same - Google Patents

Description

The present invention relates to a ceramic joined body and a solid oxide fuel cell using the same. More specifically, the present invention relates to a ceramic joined body that has good bonding properties between a ceramic substrate and a metal frame plate that holds the ceramic substrate, and gas hardly leaks from a bonded portion even after long-term use, and a solid oxide fuel cell using the same.
The ceramic joined body can be widely used in a solid electrolyte fuel cell that generates electric power using a ceramic solid electrolyte and a reaction separation membrane. The reaction separation membrane can be used in a hydrogen production apparatus, an oxygen concentrator, or the like.

In an electrolyte-supported solid electrolyte fuel cell using a thick electrolyte as a substrate, a compression seal (see Patent Document 1) and a seal with a sealing material (see Patent Document 2) are used so that fuel gas and air are not mixed. Various gas seal structures such as.) Are being studied.
However, the electrolyte support type has high resistance due to the thickness of the electrolyte and has poor power generation efficiency. For this reason, a structure in which the electrolyte is thinned using a porous electrode as a support has been studied. For example, a cell of a fuel electrode-supported fuel cell is a ceramic laminate that is relatively easy to warp because different materials are laminated and integrally sintered. However, since an electrolyte that has high electrical resistance is formed thinly, The resistance is reduced, and the operating temperature of the fixed electrolyte fuel cell can be lowered. For this reason, it becomes possible to reduce the heat-resistant limit of a junction part. However, fuel gas or combustion-supporting gas may leak from the porous electrode.
In addition, it is mentioned that a metal holding thin plate frame is bonded to a ceramic substrate (see Patent Document 3). As illustrated in FIGS. 10 and 11, the metal substrate is heated by heat treatment during bonding of the ceramic substrate. In some cases, wrinkles, undulations, etc. may occur at the joint of the holding thin plate frame.

JP-A-6-29034 JP 10-199555 A JP 2000-331692 A

Furthermore, when producing a large ceramic substrate, it is difficult to form a flat plate. In particular, when the fuel electrode and the electrolyte layer are integrally fired, such as a fuel electrode-supported fuel cell, the dissimilar materials are laminated, so the shrinkage behavior during firing is different, causing deformation such as warpage, undulation, and unevenness. It becomes. In addition, it is difficult to correct these deformations.
Furthermore, if there is such a deformation, a gap with the frame plate is likely to occur, and there may be a gap during production and use, resulting in a gas leak. It is required to be a seal.

  The present invention solves the above-mentioned problems, and even a ceramic substrate with warpage, undulation, and unevenness has good bondability with a metal frame plate to hold it, and it is a solid oxide fuel cell and reaction separation It is an object of the present invention to provide a ceramic joined body including a joined portion having gas sealability and heat resistance that can sufficiently withstand a long-term operation for a membrane and the like, and a solid electrolyte fuel cell using the same. In addition, there is a problem in that the bonding material is unevenly distributed in the bonding portion, and excess bonding material accumulates outside the bonding portion, causing defects, but the occurrence of the defect is suppressed, and the ceramic bonded body having a stable bonding portion It is another object of the present invention to provide a solid oxide fuel cell using the same.

The solid oxide fuel cell of the present invention is as follows.
1. A ceramic substrate and a metal frame plate bonded to a peripheral portion of the ceramic substrate, and a thickness of a bonding layer in the bonded portion of the ceramic substrate and the metal frame plate is 5 to 200 μm. The metal frame plate is joined by brazing ,
Ceramic bonding characterized in that the metal frame plate, the bonding material made of brazing, and the ceramic substrate are stacked in this order on a heat-resistant cushioning material, and further subjected to heat treatment in a state in which pressure is applied in the stacking direction. body.
2. The metal frame plate has a thickness of 0.02 to 0.5 mm. The ceramic joined body according to 1.
3 . The pressure is 500 Pa or more . Or 2. The ceramic joined body according to 1.
4 . The ceramic substrate is a laminate of a fuel electrode, a solid electrolyte layer, and an air electrode constituting a solid electrolyte fuel cell, and the metal frame plate is bonded to the solid electrolyte layer . To 3. The ceramic joined body according to any one of the above.
5 . The ceramic substrate is a reaction separation membrane. Thru 3 . The ceramic joined body according to any one of the above.
6 . Above 1. To 4 . A solid oxide fuel cell comprising the ceramic joined body according to any one of the above.

According to the ceramic joined body of the present invention, the thickness of the joining layer of the joined portion of the ceramic substrate and the metal frame plate is set within a predetermined range, so that the joining property between the two is improved, and the solid oxide fuel cell and reaction In the case of using the present ceramic joined body for the separation membrane, it can sufficiently withstand long-term use.
Moreover, the ceramic base and the metal frame plate so brazed prevents gas leakage from the joint portion, it is possible to obtain a gas seal which can withstand a long time at 500 ° C. or higher environment.
Furthermore, when the thickness of the metal frame is 0.5 mm or less, the metal frame plate can be deformed in accordance with the surface shape on the end side of the ceramic substrate and can be provided with a tightly joined portion.
Further, stacking a metal frame body or the like on the heat-resistant cushioning material, since further bonded by heat treatment in a condition of a pressure, the metal frame plate is adhered to the ceramic base, it is provided with a joint gas leakage it can.
Furthermore, by setting the pressure to 500 Pa or more, it is possible to provide a joint portion in which the metal frame plate is in close contact with the ceramic substrate.
When used in a solid oxide fuel cell using such a ceramic joined body, it is possible to prevent gas leakage from the joined portion and withstand long-time operation in an environment of 500 ° C. or higher.
When such a ceramic joined body is used for the reaction separation membrane, it is possible to prevent gas leakage from the joined portion and endure long-time operation.
A solid oxide fuel cell using such a ceramic joined body can prevent gas leakage from the joined portion and can withstand a long time in an environment of 500 ° C. or higher.

Hereinafter, the ceramic joined body of the present invention will be described in detail with reference to FIGS.
1. Configuration of Ceramic Bonded Body This ceramic bonded body includes a flat ceramic substrate and a metal frame plate provided on the peripheral edge of the ceramic substrate.
The material of the “ceramic base” is not particularly limited, and examples thereof include oxide ceramics, nitride ceramics, carbide ceramics, and silicide ceramics. Examples of oxide ceramics include zirconia, magnesia, spinel, alumina, and titania. Moreover, the ceramic which consists of complex oxide containing 2 or more types of elements is mentioned. Examples of nitride ceramics include silicon nitride, titanium nitride, boron nitride and the like. Examples of the carbide ceramics include silicon carbide and tungsten carbide. Examples of silicide ceramics include molybdenum silicide. These ceramics can be selected according to the application of the ceramic joined body.

For example, the material of the ceramic base to be used in the solid electrolyte layer and electrode, and the like constituting the solid electrolyte fuel _{cell, NiO, YSZ, La 1-} x Sr x MnO 3 composite oxide, BaCeO ₃ based oxide and LaGaO ₃ A system oxide or the like can be used. The ceramic substrate may be formed from a single layer of ceramic sintered body, or may be formed from a plurality of layers of ceramic sintered body. For example, a ceramic substrate in which three layers of a solid electrolyte and an air electrode are stacked on a fuel electrode that is the main component of the substrate and has the largest thickness can be given. Furthermore, when it consists of multiple layers, an arbitrary layer and a metal frame can be joined. For example, in the above-described three-layer ceramic substrate, any one of the fuel electrode, the solid electrolyte, and the air electrode can be bonded to the metal frame.

The ceramic substrate used for the reaction separation membrane is composed of oxygen-conducting ceramics such as YSZ and LaGaO ₃ -based oxides, proton-conducting ceramics such as BaCeO ₃ -based oxides that transmit only specific gases such as oxygen, and hydrogen permeability. A ceramic support such as alumina for holding metallic palladium can be used.
Further, the shape of the ceramic substrate is not particularly limited, and examples thereof include a quadrangular shape (a square shape, a rectangular shape, a trapezoidal shape and the like can be exemplified), a round shape (a perfect circle shape, an elliptical shape, a track shape and the like can be exemplified), and the like. be able to.
The ceramic substrate is preferably flat with few irregularities on the joint surface with the metal frame. Further, the height difference D (for example, see FIG. 7) that appears due to the unevenness is preferably 1.0 mm (particularly preferably 0.9 mm or less, more preferably 0.8 mm or less). If the height difference D is too large, wrinkles and undulations are likely to occur at the joint of the metal frame during joining, and sufficient joining strength cannot be obtained. Moreover, it is because a clearance gap arises in a junction part and it causes a gas leak.

The “metal frame plate” is used as a separator when the ceramic joined body is used for a solid oxide fuel cell or a reaction separation membrane, and any metal can be selected according to the application. For example, when used as an isolation separator for a solid oxide fuel cell, the fuel gas and the combustion-supporting gas may be isolated so as not to be mixed without deteriorating in the range of 500 ° C. to 900 ° C., which is the temperature during use. Possible metals can be selected. Examples of such metals include stainless steel, nickel-based alloys, and chromium-based alloys.
Examples of the stainless steel include ferritic stainless steel, martensitic stainless steel, and austenitic stainless steel. Examples of ferritic stainless steel include SUS434 and SUS405 in addition to SUS430. Examples of martensitic stainless steel include SUS403, SUS410, and SUS431. Examples of austenitic stainless steel include SUS201, SUS301, and SUS305. Further, examples of the nickel-based alloy include Inconel 600, Inconel 718, Incoloy 802, and the like. Examples of the chromium-based alloy include Ducrloy CRF (94Cr5Fe1Y ₂ O ₃ ). These various heat-resistant alloys can be selected according to the use of the solid oxide fuel cell, respectively.

  Further, the thickness of the metal frame plate is preferably 0.02 to 0.5 mm (preferably 0.03 to 0.4 mm, more preferably 0.03 to 0.3 mm). This is because if the thickness exceeds 0.5 mm, the amount of deformation of the metal frame plate becomes small during bonding with the ceramic substrate, and deformation along the planar shape of the ceramic substrate cannot be expected. That is, since the thin metal frame plate is more easily deformed, it is suitable for obtaining a good joint.

  The ceramic bonded body preferably includes a bonded portion in which the metal frame is in close contact with the shape of the peripheral edge of the ceramic substrate. As illustrated in FIG. 6, the “peripheral portion” is a surface on the peripheral side of the ceramic substrate 100, and is a portion having a width necessary for joining with the metal frame. In addition, this “along the shape of the ceramic sintered body” means that the joint portion of the metal frame plate with the ceramic substrate is deformed in accordance with the surface shape of the peripheral portion of the ceramic substrate. This indicates that the thickness of the bonding layer is recognized to be uniform. The thickness S (see, for example, FIG. 6) is preferably 5 to 200 μm (particularly preferably 10 to 180 μm, more preferably 10 to 170 μm).

Method of joining ceramics base and the metal frame plate, the air-tightness Chi retention, heat resistance good bonding method serving brazing is used.
The brazing material used for brazing is not particularly limited, and examples thereof include silver containing palladium (for example, 2 to 30% by mass, preferably 3 to 10% by mass).

Further, as illustrated in FIGS. 8 and 9, the method of joining the ceramic substrate and the metal frame plate is performed on the heat-resistant buffer material (setter) 95 on the metal plate 23 for the metal frame plate and the bonding material (not shown). ), Stacking ceramics 100 as a ceramic substrate in this order, and adopting a method of performing heat treatment in a state where pressure is applied using a weight 96 or the like .
The pressure is preferably 500 Pa (about 5 g / cm ² , particularly preferably 550 Pa, more preferably 600 Pa) or more.

Examples of the “heat-resistant buffer material” include heat-resistant materials such as ceramics, metal, and glass. Moreover, felt, a nonwoven fabric, a woven fabric, etc. can be mentioned as a form of the heat resistant buffer material using ceramics and glass. Furthermore, examples of the form of the heat-resistant cushioning material using metal include foams, porous bodies, felts, nonwoven fabrics, and woven fabrics. By laying such a heat-resistant cushioning material and performing a heat treatment for bonding, a good bonded portion can be obtained along the metal frame plate smoothly along the peripheral edge of the ceramic substrate.
Examples of the ceramic include alumina, magnesia, zirconia, and the like, and examples of the metal include stainless steel, nickel, copper, and the like.

2. Structure of Solid Electrolyte Fuel Cell A fuel electrode support type solid oxide fuel cell 1 using such a ceramic joined body is illustrated in FIG. The solid electrolyte fuel cell 1 may have any structure as long as the fuel electrode 12, the solid electrolyte layer 11, and the air electrode 13 are laminated in this order, and the separation between the fuel electrode 12 and the air electrode 13 is separated by an isolation separator 23. Any of the fuel electrode 12, the solid electrolyte layer 11, and the air electrode 13 can be used as a substrate.

The solid oxide fuel cell 1 has various structures, and a plurality of power generation layers 10 are formed by being stacked via metal inter-cell separators 21. In the fuel cell 1, each power generation layer 10 includes a single cell 100, and each single cell 100 is provided with a solid electrolyte layer 11, a fuel electrode 12 provided on one surface of the solid electrolyte layer 11, and another surface. The air electrode 13 is provided. Further, the single cell 100 corresponds to a ceramic substrate, and the isolation separator 23 corresponds to a metal frame plate.
Furthermore, the fuel electrode 12 and air electrode 13 of each single cell 100 and the inter-cell separator 21 can be electrically connected by a fuel electrode side current collector 41 and an air electrode side current collector 42, respectively. Each power generation layer 10 includes an isolation separator 23 for isolating the flow path of the fuel gas from the flow path of the air that is the combustion-supporting gas. Furthermore, in order to electrically insulate between the respective power generation layers 10, an insulating plate 7 made of an insulator such as ceramic may be disposed at a predetermined portion in the stacking direction.

The solid electrolyte layer 11 is preferably made of at least one of ZrO ₂ , BaCeO ₃ -based oxide, and LaGaO ₃ -based oxide. Of these, a solid electrolyte using a ZrO ₂ oxide is particularly preferable.
The solid electrolyte layer 11 moves at least a part of one of the fuel gas introduced into the fuel electrode 12 and the combustion-supporting gas introduced into the air electrode 13 as ions when the solid electrolyte fuel cell 1 is operated. It has ionic conductivity. Although what kind of ion can be conducted is not particularly limited, examples of the ion include oxygen ion and hydrogen ion.
The thickness of the solid electrolyte layer 11 can be set to 5 to 100 μm, particularly 5 to 50 μm, and further 5 to 30 μm in consideration of electric resistance and strength.

The fuel electrode 12 can be formed of Ni, YSZ, or the like. The fuel electrode 12 is in contact with a fuel gas serving as a hydrogen source and functions as a negative electrode in the single cell 100.
Further, the material used for forming the fuel electrode 12 is not limited to Ni and YSZ, and can be appropriately selected depending on the use conditions of the solid electrolyte fuel cell 1 and the like. Examples of this material include metals such as Pt, Au, Ag, Cu, Pd, Ir, Ru, Rh, Ni, and Fe. These metals may be used alone or in an alloy of two or more metals. Further, a mixture (including cermet) of these metals and / or alloys and zirconia ceramics such as zirconia stabilized by at least one of Y and rare earth elements, ceria ceramics, and ceramics such as manganese oxide. ). Furthermore, the mixture etc. of the oxide of metals, such as Ni and Cu, and at least 1 sort (s) of the said ceramic are mentioned.
Further, the planar shape of the fuel electrode 12 is not particularly limited.

The air electrode 13 can be formed of, for example, La _1-x Sr _x MnO ₃ composite oxide. The air electrode 13 is in contact with a combustion-supporting gas serving as an oxygen source and functions as a positive electrode in the single cell 100.
The material used for forming the air electrode 13 is not limited to the La _1-x Sr _x MnO ₃ -based composite oxide, and can be appropriately selected depending on the use conditions of the solid oxide fuel cell 1. Examples of this material include metals such as Pt, Au, Ag, Pd, Ir, Ru, and Rh. These metals may be used alone or in an alloy of two or more metals. Further, oxides such as La, Sr, Ce, Co, and Mn (for example, La ₂ O ₃ , SrO, Ce ₂ O ₃ , Co ₂ O ₃ , MnO _2, and FeO) can be used. In addition, various composite oxides containing at least one of La, Sr, Ce, Co, Mn, and the like (for example, La _1-x Sr _x FeO ₃ composite oxide, La _1-x Sr _x Co _{1 -Y} Fe _y O ₃ -based composite oxide, Pr _1-x Ba _x Co _1-y Fe _y O ₃ -based composite oxide, Sm _1-x Sr _x Co _1-y Fe _y O ₃ -based composite oxide) Is mentioned.

The material of the fuel electrode side current collector 41 is preferably a metal, and can be formed of, for example, Ni or a Ni-based alloy. Examples of the form of the fuel electrode side current collector 41 include felts or meshes made of a porous body, a foam, and metal fibers.
As the material of the air electrode side current collector 42, a metal and a conductive ceramic can be used. As this metal, the same material as the fuel electrode side current collector 41 can be used, but an inelastic dense plate-like body may be used.

The air electrode side current collector 42 can be provided so as to be in contact with the air electrode 13 on one surface and in contact with the inter-cell separator 21 on the other surface. In addition, the air electrode side current collector 42 and the intercell separator 21 can be bonded to each other using a conductive bonding material such as a brazing material on at least a part of the surface in contact with the intercell separator 21. Such a bonding material is not particularly limited as long as the air electrode side current collector 42 and the inter-cell separator 21 are brought into close contact with each other and can be stably contacted to prevent an increase in contact resistance.
In the solid oxide fuel cell 1, there are many portions that need to be hermetically sealed with a bonding material or the like, such as between the air electrode current collector 42 and the inter-cell separator 21. Can be joined at the same time. Moreover, glass bonding may be used, and a compression seal may be used.
Furthermore, these current collectors 41 and 42 may be made of only one kind of material, or may be made of two or more kinds of materials. Moreover, the aggregate | assembly of the block which consists of a different material may be sufficient.

The material of the inter-cell separator 21 is formed of a metal, in particular, a heat-resistant alloy such as stainless steel, a nickel base alloy, or a chromium base alloy. When no other power generation layer is stacked on the upper surface of the inter-cell separator 21, the lid member 22 functions. When no other power generation layer is stacked on the lower surface of the inter-cell separator 21, the bottom member 26 functions. .
Furthermore, depending on the structure of the solid oxide fuel cell 1, an inter-cell separator 21 in which a flow path of fuel gas or combustion-supporting gas is formed can be used.

  Fuel gas is hydrogen, hydrocarbon as a hydrogen source, mixed gas of hydrogen and hydrocarbon, fuel gas obtained by passing these gases through water at a predetermined temperature and humidified, and fuel gas obtained by mixing these gases with water vapor Etc. The hydrocarbon is not particularly limited, and examples thereof include natural gas, naphtha, and coal gasification gas. Further, the main components are saturated hydrocarbons having 1 to 10, preferably 1 to 7, more preferably 1 to 4 carbon atoms such as methane, ethane, propane, butane and pentane, and unsaturated hydrocarbons such as ethylene and propylene. Those having a saturated hydrocarbon as a main component are more preferable. These fuel gas may use only 1 type and can also use 2 or more types together. Moreover, you may contain inert gas, such as nitrogen and argon of 50 volume% or less.

  Examples of the combustion-supporting gas include a mixed gas of oxygen and another gas. The mixed gas may contain 80% by volume or less of an inert gas such as nitrogen and argon. Among these combustion-supporting gases, air (containing about 80% by volume of nitrogen) is preferable because it is safe and inexpensive.

Will be specifically described below ceramic bonding article and a solid electrolyte fuel cell 1 using the same of the present invention by experiments Example (Experimental Examples 1,3,5,6,7 are examples, experimental example 2 4, 8, and 9 are reference examples) .
1. Solid electrolyte fuel cell of the solid electrolyte fuel cell 1 of the structure (1) unit cell 100 and the various separators such present experiment example 1, as shown in Figures 1-3, three power generation layer 10 (10a, 10b, 10c) is laminated. Further, the isolation separator 23 is arranged in a horizontal state without bending. In addition, the number of the power generation layers 10 is not limited to 3, and can be configured by an arbitrary number.
In the solid oxide fuel cell 1, three power generation layers 10 a to 10 c are stacked via an intercell separator 21. The single cell 100 provided in each power generation layer 10 has a fuel electrode 12 as a base, and a solid electrolyte layer 11 and an air electrode 13 are laminated thereon. The single cell 100 and the isolation separator 23 are a ceramic substrate and a metal frame constituting a ceramic joined body.
The solid electrolyte layer 11 is made of 8YSZ, has a square planar shape, and a thickness of 30 μm.
The fuel electrode 12 is made of Ni and 8YSZ, has the same shape and size in the planar direction as the solid electrolyte layer 11, and has a thickness of 2 mm.
The air electrode 13 is made of LSM (La _0.8 Sr _0.2 MnO ₃ ), has the same planar shape as the solid electrolyte layer 11, is smaller than the solid electrolyte layer 11, and has a thickness of 30 μm.

The upper power generation layer 10 a includes a fuel electrode side current collector 41 made of nickel felt disposed on the upper surface of the inter-cell separator 21, a single cell 100, an air electrode side current collector 42 made of Inconel fiber mesh, and a lid member 22. Are provided in this order. The air electrode side current collector 42 and the lid member 22 are brazed over the entire surface in contact with the air electrode side current collector 42 and the lid member 22, and the joint portion 6 is formed.
The upper power generation layer 10a has an insulating surface made of a MgO—MgAl ₂ O ₄ sintered body whose lower surface is bonded to the solid electrolyte layer 11 and the metal frame body 82 through the bonding portion 6 and whose upper surface is an insulating ceramic. It further has an isolation separator 23 joined to the lid member 22 via the plate 7 and the metal frame 81.

The intermediate power generation layer 10b includes a fuel electrode side current collector 41, a single cell 100, and an air electrode side current collector 42 arranged in this order on the upper surface of the inter-cell separator 21. The air electrode side current collector 42 is brazed in the same manner as in the case of the lower surface of the inter-cell separator 21 and the upper power generation layer 10a to form the joint 6.
Further, the intermediate power generation layer 10 b has a lower surface bonded to the solid electrolyte layer 11 and the metal frame 84 via the bonding portion 6, and an upper surface connected to the inter-cell separator 21 via the insulating plate 7 and the metal frame 83. And an isolating separator 23 joined to each other.

The lower power generation layer 10 c includes a fuel electrode side current collector 41, a single cell 100, and an air electrode side current collector 42 arranged in this order on the upper surface of the bottom member 26. The air electrode side current collector 42 is brazed in the same manner as in the case of the lower surface of the inter-cell separator 21 and the upper power generation layer 10a to form the joint 6.
The lower power generation layer 10c has a lower surface joined to the solid electrolyte layer 11 and the metal frame 86 via the joint 6 and an upper surface connected to the inter-cell separator 21 via the insulating plate 7 and the metal frame 85, respectively. It further has the isolation | separation separator 23 joined.

The inter-cell separator 21, the lid member 22, the isolation separator 23, the bottom member 26, and the metal frame bodies 81 to 86 are all formed of SUS430. This is because it is a heat-resistant alloy having substantially the same thermal expansion coefficient as the single cell. Furthermore, the thickness of the isolation separator 23 is 0.2 mm.
Further, the lid member 22 and the metal frame 81, the upper power generation layer isolation separator 23 and the metal frame 82, the metal frame 82 and the inter-cell separator 21, the inter-cell separator 21 and the metal frame 83, the intermediate power generation Layer separator 23 and metal frame 84, metal frame 84 and inter-cell separator 21, inter-cell separator 21 and metal frame 85, lower power generation layer separator 23 and metal frame 86, metal The frame body 86 and the bottom member 26 are each joined by a joining material, and the joining part 6 is formed. In addition, each metal frame and the insulating plate 7, the separator 23 and the insulating plate 7 are also bonded by a bonding material, and a bonded portion 6 is formed.

(2) Gas introduction pipe, exhaust pipe, etc. As shown in FIG. 2 in the upper power generation layer 10a, the space formed between the isolation separator 23 and the inter-cell separator 21 of the upper power generation layer 10a includes the upper power generation layer 10a. A fuel gas introduction pipe 91 for introducing fuel gas into the fuel electrode 12 is opened. A fuel gas discharge pipe 92 for discharging fuel gas from the fuel electrode 12 of the upper power generation layer 10a is opened on the side of the space facing the opening of the fuel gas introduction pipe 91. Further, as shown in FIG. 3, in the space formed between the lid member 22 and the isolation separator 23, the combustion-supporting gas for introducing the combustion-supporting gas into the air electrode 13 of the upper power generation layer 10a is introduced. A tube 93 is open. In addition, a combustion-supporting gas discharge pipe 94 for discharging combustion-supporting gas from the air electrode 13 of the upper power generation layer 10a is opened on the side of the space facing the opening of the combustion-supporting gas introduction pipe 93. ing.

  Further, as shown in FIG. 2 in the intermediate power generation layer 10b, a fuel gas is introduced into the fuel electrode 12 of the intermediate power generation layer 10b in the space formed between the isolation separator 23 and the inter-cell separator 21. The fuel gas introduction pipe 91 is opened. Further, a fuel gas discharge pipe 92 for discharging the fuel gas from the fuel electrode 12 of the intermediate power generation layer 10b is opened on the side of the space facing the opening of the fuel gas introduction pipe 91. In addition, as shown in FIG. 3, in the space formed between the inter-cell separator 21 and the isolation separator 23, the combustion support property for introducing the support gas into the air electrode 13 of the intermediate power generation layer 10 b. A gas introduction pipe 93 is opened. Further, a combustion-supporting gas discharge pipe 94 for discharging combustion-supporting gas from the air electrode 13 of the intermediate power generation layer 10b is opened on the side of the space facing the opening of the combustion-supporting gas introduction pipe 93. is doing.

  Further, as shown in FIG. 2 in the lower power generation layer 10c, a fuel gas for introducing fuel gas into the fuel electrode 12 of the lower power generation layer 10c is formed in a space formed between the isolation separator 23 and the bottom member 26. The introduction pipe 91 is open. A fuel gas discharge pipe 92 for discharging the fuel gas from the fuel electrode 12 of the lower power generation layer 10c is opened on the side of the space facing the opening of the fuel gas introduction pipe 91. Further, as shown in FIG. 3, in the space formed between the inter-cell separator 21 and the isolation separator 23, a support gas is introduced to introduce a support gas into the air electrode 13 of the lower power generation layer. A tube 93 is open. Further, a combustion-supporting gas discharge pipe 94 for discharging combustion-supporting gas from the air electrode 13 of the lower power generation layer 10c opens on the side of the space facing the opening of the combustion-supporting gas introduction pipe 93. ing.

  In addition, each pipe for introducing or discharging fuel gas or combustion-supporting gas to each of the power generation layers 10a to 10c has a structure in which a side pipe is attached to the main pipe. Fuel gas and combustion-supporting gas are simultaneously introduced into and discharged from each single cell 10c. Further, in the case of the first embodiment, the fuel gas introduction pipe and the fuel gas discharge pipe, and the fuel support gas introduction pipe and the combustion support gas discharge pipe are respectively circulated in the opposing direction. It is attached to such a position. Thereby, each fuel electrode of each unit cell 100 of each electric power generation layer 10a-10c and fuel gas, and an air electrode and combustion-supporting gas can be made to contact each efficiently.

2. Case of generating electric power using a solid electrolyte fuel cell of the fuel gas and combustion-supporting gas Experiment Example 1, the fuel electrode side by introducing a fuel gas, the air electrode side introduces a combustion-supporting gas.

3. Power generation and extraction of power of the solid oxide fuel cell In this solid oxide fuel cell 1, the air electrode 13 of the upper power generation layer 10a is electrically connected to the lid member 22 via the air electrode side current collector 42. Yes. The fuel electrode 12 of the upper power generation layer 10 a is electrically connected to the inter-cell separator 21 via the fuel electrode side current collector 41. The inter-cell separator 21 is connected to the air electrode 13 of the intermediate power generation layer 10b through the air electrode side current collector 42. Further, the fuel electrode 12 of the intermediate power generation layer 10 b is electrically connected to the inter-cell separator 21 via the fuel electrode side current collector 41. The inter-cell separator 21 is electrically connected to the air electrode 13 of the lower power generation layer 10c through the air electrode side current collector 42. Further, the fuel electrode 12 of the lower power generation layer 10 c is electrically connected to the bottom member 26 through the fuel electrode side current collector 41. As described above, the power generation layers 10 a to 10 c are connected in series, and power can be taken out from the lid member 22 and the bottom member 26.
The solid electrolyte fuel cell 1 is heated to a predetermined operating temperature, a fuel gas such as hydrogen is introduced into the fuel gas introduction pipe 91 and brought into contact with the fuel electrode 12, and air is introduced into the combustion supporting gas introduction pipe 93. It is possible to function as a fuel cell by introducing a combustion-supporting gas such as the above and bringing it into contact with the air electrode 13.
In the solid electrolyte fuel cell 1, three single cells are each supported by a fuel electrode. In this structure, current can be taken out even at an operating temperature of about 600 ° C.

4). Test (1) Bondability evaluation In order to examine the performance of the ceramic bonded body used in such a solid oxide fuel cell, the following bondability evaluation was performed. This ceramic joined body is obtained by joining the ceramic substrate 100 and the metal frame 23 as shown in FIGS.
The used ceramic substrate 100 has a 200 mm square and a square shape. The ceramic substrate 100 is a fuel electrode layer made of Ni and 8YSZ having a thickness of 2 mm, and a solid electrolyte layer laminate made of 8YSZ having a thickness of 30 μm.
The metal frame 23 is a SUS430 having a 300 mm square and a thickness of 0.2 mm, and a square hole having a 180 mm square is provided at the center. For this reason, the width | variety of the joining margin of a ceramic base | substrate and a metal frame is 10 mm.
8 and 9, a ceramic substrate 100, a bonding material (not shown), and a metal frame 23 are laminated on a setter 95, and a 500 g weight 96 is placed on the ceramic substrate 100, 1050 ° C., 30 Bonding was performed by performing a heat treatment for a minute. The results are shown in Table 1.
As the setter, an alumina ceramic plate, a SUS430 metal plate, an alumina ceramic felt (thickness: 2 mm), and a SUS430 metal foam (thickness: 2 mm) were used.
As the bonding material, brazing or glass bonding was used. Further, brazing was performed with a brazing material in which 5% by mass of palladium was added to silver. For glass bonding, multi-component added silicate glass having a crystallization temperature of 900 ° C. was used.

For the ceramic joined body produced by combining the above conditions shown in Table 1, the height difference of the ceramic substrate, the joining condition, and the thickness of the joining layer were determined.
The height difference of the ceramic substrate was determined by measuring the surface shape using a surface roughness measuring instrument.
Further, in order to investigate the bonding state between the ceramic substrate and the metal frame 23 and the thickness of the bonding layer, the bonded body was embedded in resin and then cut so that the bonded portion was exposed. Thereafter, the cross-section of the joint part that had been mirror-polished was examined with an optical microscope, and the joining state was confirmed as to whether or not the brazing material and glass filled the gap between the ceramic substrate and the metal frame. Furthermore, the thickness of the bonding layer was measured using an eyepiece with a scale provided in the optical microscope.

As shown in Table 1, a heat-resistant cushioning material setter, experimental examples 1 to 4 using a ceramic felt or metal foam, be any bonding material, the metal frame to the surface shape of the ceramic base It joined in the state where the shape of the board followed, and the favorable junction part without a clearance gap in a junction part was obtained. Although experimental examples 2 and 4 there is a variation of 60μm in the bonding layer thickness, the thickness are within the range of 100~160μm and 110~170μm and 5 to 200 [mu] m, the junction of the metal plate body 23 No wrinkles or undulations were observed, and a good joint was obtained. The variation of the bonding layer thickness of Experiment Example 1 is 30 [mu] m, particularly good joint was obtained.
On the other hand, in Comparative Examples 1 to 4 using a non-buffering material using a ceramic flat plate and a metal plate, it was confirmed that a gap was generated regardless of the bonding material. Further, in any of the comparative examples, wrinkles and waviness as illustrated in FIGS. 10 and 11 are observed in the joint portion of the metal frame plate 23, and the thickness of the joint layer exceeds 200 μm, and the maximum is 600 μm (Comparative Example 1). Reached. Further, the thickness variation of the bonding layer was as large as 480 (Comparative Examples 2 and 4) to 580 (Comparative Example 1) μm. It was confirmed that there was a large gap that was not filled with the brazing material at the end of the ceramic substrate of these comparative examples. The maximum value of the bonding layer thickness in Table 1 is the distance between the ceramic substrate including this gap and the metal frame plate.

(2) Durability Evaluation In order to investigate whether or not the gas sealability is maintained over a long period of time, the following durability evaluation was performed. The ceramic substrate and the metal frame used for the durability evaluation have the same shape and configuration as those of (1) the bondability evaluation, and those produced by the combinations shown in Table 2 were used. After laminating these on the setter shown in Table 2, brazing or glass bonding was performed to obtain a ceramic bonded body.
The leak test used for durability evaluation is an aqueous solution colored with a red dye from the inner hole of the metal frame plate of the joint after heating the ceramic joined body at 700 ° C. for 500 hours, 1000 hours and 3000 hours. The red liquid is applied, and it is visually checked whether the red liquid permeates into the gap between the opposite ceramic substrate end and the metal frame, and when not colored red, × It was. The results are shown in Table 2.

As shown in Table 2, the experiment example 5 to 10, and joined in a state in which the shape along the metal frame plate to the surface shape of the ceramic base, the use for 3000 hours without penetration red liquid, the gas seal Durability was confirmed. On the other hand, in Comparative Examples 5 and 6, the penetration of the red liquid could not be confirmed when the time exceeded 500 hours. However, when the test was conducted for 1000 hours, it was found that the red liquid penetrated and leaked.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention depending on the purpose, application, and the like. For example, the stainless steel forming the lid member, each separator, and the bottom member includes ferritic stainless steel, martensitic stainless steel, and austenitic stainless steel. Examples of ferritic stainless steel include SUS434, SUS405, and the like in addition to SUS430. Examples of martensitic stainless steel include SUS403, SUS410, and SUS431. Examples of austenitic stainless steel include SUS201, SUS301, and SUS305. Further, examples of the nickel-based alloy include Inconel 600, Inconel 718, Incoloy 802, and the like. Examples of the chromium-based alloy include Ducrloy CRF (94Cr5Fe1Y ₂ O ₃ ). These various heat-resistant alloys can be selected depending on the use of the laminate.

  The planar shape of the unit cell or the like can be a rectangle, a circle, an ellipse, or the like, and a solid oxide fuel cell having a similar planar shape can be obtained. In a solid oxide fuel cell, metal molded bodies such as various separators can be joined by a method such as welding.

  The air electrode can also be formed as a substrate that supports the strength of the single cell. In the case of the air electrode support type, the thickness of the air electrode is preferably 20 times or more that of the solid electrolyte layer. The thickness of the air electrode is preferably 200 to 3000 μm, particularly 500 to 2000 μm. If it is less than 200 μm, it will not function effectively as a substrate, and if it exceeds 3000 μm, the power generation efficiency per volume tends to decrease. On the other hand, in the case of the fuel electrode support type, the thickness of the air electrode is preferably 10 to 100 μm, particularly 20 to 50 μm. When the thickness is less than 10 μm, the electrode may not function sufficiently, and when the thickness exceeds 100 μm, the solid electrolyte layer may be peeled off.

It is a model perspective view for demonstrating the structure of the solid electrolyte form fuel cell using this ceramic joined body. It is AA sectional drawing in FIG. 1 for demonstrating the structure of the solid oxide fuel cell using this ceramic joined body. It is BB sectional drawing in FIG. 1 for demonstrating the structure of the solid oxide fuel cell using this ceramic joined body. It is a model perspective view which shows the external appearance of a ceramic joined body. It is a model perspective view which shows the external appearance of a ceramic joined body. It is a schematic cross section of a ceramic joined body. It is a schematic cross section of a ceramic substrate. It is a model perspective view for demonstrating the stacking order when producing a ceramic joined body. It is a schematic cross section for demonstrating the stacking order when producing a ceramic joined body. It is a model perspective view for demonstrating the ceramic joined body which a clearance gap is made in a junction part and the wrinkles and the wave | undulation approached the metal frame board. It is a schematic cross section for explaining a ceramic joined body in which a gap is formed in a joined portion and a metal frame plate appears to have wrinkles and waviness.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1; Solid electrolyte fuel cell, 10; Electric power generation layer, 100; Single cell (ceramics base), 11; Solid electrolyte layer, 12; Fuel electrode, 13; Air electrode, 21; Intercell separator, 22; Intermediate separator), 23; isolation separator (metal frame), 26; bottom member (inter-cell separator), 31; fuel gas flow path, 32; combustion-supporting gas flow path, 41; fuel electrode side current collector 42; air electrode side current collector, 6; junction, 7; insulating plate, 81, 82, 83, 84, 85, 86; metal frame, 91; fuel gas introduction pipe, 92; 93; Supporting gas introduction pipe, 94; Supporting gas exhaust pipe, 95; Setter.

Claims (6)

A ceramic substrate and a metal frame plate joined to the peripheral edge of the ceramic substrate;
The thickness of the bonding layer at the bonded portion of the ceramic substrate and the metal frame plate is 5 to 200 μm,
The ceramic substrate and the metal frame plate are joined by brazing ,
Ceramic bonding characterized in that the metal frame plate, the bonding material made of brazing, and the ceramic substrate are stacked in this order on a heat-resistant cushioning material, and further subjected to heat treatment in a state in which pressure is applied in the stacking direction. body.   The ceramic joined body according to claim 1, wherein the metal frame plate has a thickness of 0.02 to 0.5 mm. The ceramic joined body according to claim 1 or 2 , wherein the pressure is 500 Pa or more. The ceramic base has a fuel electrode which constitutes the solid electrolyte fuel cell, a solid electrolyte layer and a laminate of an air electrode, any one of claims 1 to 3 the metal frame plate is bonded to the solid electrolyte layer The ceramic joined body according to item . The ceramic joined body according to any one of claims 1 to 3 , wherein the ceramic substrate is a reaction separation membrane. A solid oxide fuel cell comprising the ceramic joined body according to any one of claims 1 to 4 .

Images