JP5313717B2 - Oxygen ion conduction module and bonding material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxygen ion conduction module where various structural members are joined with air tightness held over a long period of time and where the joined part has high durability against reduction expansion, a joining material to be used for forming the joined part and a method of joining the structural members to each other using the joining material. <P>SOLUTION: The oxygen ion conduction module 10 includes an oxygen ion conductive ceramic material 12. The oxygen ion conduction ceramic material 12 is at least joined to one ceramic-made connection members 18A, B. The joined part 20 of the oxygen conduction ceramic material 12 to the joining members 18A, B is formed so as to mix two components of (a) glass in which a cristobalite crystal and/or leucite crystal is deposited in a glass matrix and (b) at least one perovskite type oxide. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an oxygen ion conduction module that selectively permeates oxygen ions, and a bonding material (sealing material) for forming a bonding portion in the module and having a low reduction expansion property.

A dense ceramic material made of oxygen ion conductor having oxygen ions (typically O ²⁻ ; also called oxide ions) is provided as a basic component of an oxygen ion conduction module (oxygen ion conduction device). Thus, oxygen can be selectively permeated and separated from the oxygen-containing gas (such as air) supplied to one surface to the other surface.

  A typical example of the oxygen ion conduction module is an oxygen separation device. Such an oxygen separation device includes an oxygen separation membrane element, and the oxygen separation membrane element is made of an oxygen separation membrane material formed by forming an oxygen ion conductor in a film shape (typically a porous substrate). ) Is provided. Such an oxygen separation device can be suitably used as an effective oxygen purification means replacing, for example, a cryogenic separation method or a PSA (Pressure Swing Adsorption) method. When constructing an oxygen separation device having such a configuration, the oxygen separation membrane element is joined to various members and includes a joint (seal) portion that can maintain high hermeticity even in a high temperature range (for example, 800 ° C. to 1000 ° C.). Need to be built with. As a joining (seal) material for forming such a highly airtight joint, for example, a glass material or a metal material has been studied.

Alternatively, as a typical example of the oxygen ion conduction module, there is a solid oxide fuel cell (hereinafter, also simply referred to as “SOFC”). As a basic structure (single cell), SOFC has a porous air electrode (cathode) formed on one side of a dense solid electrolyte (eg, a dense membrane layer) made of an oxygen ion conductor, and the other side. A porous fuel electrode (anode) is formed. Fuel gas (typically H ₂ (hydrogen)) is supplied to the surface of the solid electrolyte on the side where the fuel electrode is formed, and O ₂ (oxygen) is supplied to the surface of the solid electrolyte on the side where the air electrode is formed. A gas containing (typically air) is supplied.

  The SOFC is typically operated as a stack in which a plurality of single cells are stacked to obtain a high voltage. In an SOFC having such a stack structure, an interconnector is used to connect single cells. The interconnector serves as a separator that separates the oxidizing gas (oxygen-containing gas such as air) and reducing gas (fuel gas such as hydrogen) at the same time as connecting the single cells physically and electrically. Also bears. The interconnector and the surface of the solid electrolyte facing the interconnector need to be joined (sealed) so as to ensure high airtightness even when operated in a high temperature range (usually 800 ° C. to 1200 ° C.). There is.

By the way, as a solid electrolyte for SOFC, a solid electrolyte made of a zirconia-based material (typically yttria-stabilized zirconia; YSZ) is widely used due to high chemical stability and mechanical strength.
In addition, the interconnector as described above has high chemical durability and conductivity in an oxidation-reduction atmosphere at such a high temperature, considering that the SOFC operates in the high temperature range as described above, and is similar to a solid electrolyte material. It is preferably formed from a material having properties such as having a thermal expansion coefficient. As such an interconnector material, a metal material (for example, a heat-resistant alloy or an Ag (silver) composite) or a ceramic material has been proposed. As ceramic materials, as shown in Patent Documents 1 to 9, various perovskite oxide materials have been proposed. For _{example, La 1-p A p CrO} 3 ( where, A is at least one selected from the group consisting from Mg, Ca, Sr, Ba, a 0 ≦ p <1.) Such as lanthanum chromite (LaCrO ₃ ) Perovskite type oxides of the system, or perovskite type oxides whose B sites are partially substituted (doped) with other elements (for example, Si, Ti, Co, Ni or Zr), and further MTiO ₃ (where M is at least one selected from the group consisting of Li, Ca, Cu, Sr, Ba, La, Ce, Pb, and Bi.) And the like, and titanate-based perovskite oxides.
In addition, the joining material between the solid electrolyte and the interconnector has a thermal expansion coefficient similar to that of the solid electrolyte material and the interconnector material, and has a high hermeticity even at the SOFC operating temperature or higher (sealing). Materials that can be made are preferred. For example, as shown in Patent Documents 10 to 16, a mixture of stabilized zirconia and glass, a mixture of a solid electrolyte material and an interconnector material, and a mixture of glass and metal have been proposed.

JP-A-8-55629 JP-A-8-83620 JP-A-8-190922 JP-A-10-125340 Japanese Patent Laid-Open No. 11-3720 JP 2003-288919 A JP 2003-331874 A JP 2006-310090 A JP 2007-39279 A JP-A-5-330935 JP-A-8-134434 JP-A-9-129251 Japanese Patent Laid-Open No. 11-154525 JP 2004-39573 A Special table 2008-527680 Special table 2008-529256

  As described above, in the oxygen ion conduction module such as SOFC, the bonding material for bonding the members constituting the module to each other has a thermal expansion coefficient close to that of the material of the module component, A material that can be bonded (sealed) while maintaining high airtightness even at a temperature higher than the operating temperature of the module is preferable. However, since materials such as the above have poor heat resistance due to elution under the above operating temperature range and the conductivity is extremely low, the amount of bonding material made of such material and the place (area) to be applied There was a problem that was limited. In addition, since the reductive expansion coefficient of such a material is relatively high, when an oxygen ion conduction module is configured using such a material, there are a portion exposed to a reducing atmosphere and a portion exposed to an oxidizing atmosphere in the module. There is a possibility that the durability of the oxygen ion conduction module may be lowered, such as a difference in expansion degree (that is, a stress difference between the two increases and a crack). For example, when a stack composed of a single cell is formed using the above-described materials, a crack may occur in the interconnector due to a difference in expansion degree between the fuel electrode (reducing atmosphere) side and the air electrode (oxidizing atmosphere) side of the interconnector. .

  The present invention has been made in view of such a point, and its main purpose is that various components are bonded while maintaining high airtightness over a long period of time even under a high operating temperature range. To provide an oxygen ion conduction module having high durability against reductive expansion. It is another object of the present invention to provide a bonding material used for forming a bonding portion having such high airtightness, conductivity, and reduction expansion resistance. Furthermore, it is another object to provide a method for joining the constituent members of an oxygen ion conduction module using such a joining material.

In order to achieve the above object, an oxygen ion conductive module provided by the present invention includes a ceramic material having oxygen ion conductivity, and the oxygen ion conductive ceramic material is bonded to at least one ceramic connecting member. doing. Moreover, in the oxygen ion conduction module, the joint between the oxygen ion conductive ceramic material and the connection member has the following two components:
(A). A glass characterized in that cristobalite crystals and / or leucite crystals are precipitated in a glass matrix; and (b). At least one perovskite oxide;
Are formed together.

Here, the “oxygen ion conduction module” is a module (component, device) provided with a ceramic material having oxygen ion conductivity (oxygen ion conductor) as a basic constituent member, on one surface of the ceramic material. A module (configuration in which oxygen is selectively separated from the oxygen-containing gas in the process of supplying oxygen-containing gas (air, etc.) and permeating through the ceramic material, and only oxygen is permeated to the other surface of the ceramic material. Device).
In the oxygen ion conductive module according to the present invention, the joint between the oxygen ion conductive ceramic material and the connecting member is (a) a cristobalite crystal (SiO ₂ ) and / or a leucite crystal (KAlSi ₂ O ₆ ) in a glass matrix. Are deposited by mixing two components of glass (hereinafter referred to as “crystal-containing glass”) and (b) at least one perovskite oxide. Such a joint includes the above-mentioned component (a) (for example, the cristobalite and / or leucite fine crystals are precipitated in a dispersed state in the glass matrix), so that a temperature range of 800 ° C. or higher, for example, 800 ° C. to It is difficult to flow in a temperature range of 1000 ° C. Therefore, according to the oxygen ion conduction module, even when the operating temperature of the module reaches the above temperature range, there is no possibility that the joint portion between the oxygen ion conductive ceramic material and the connection member is eluted, and the mechanical strength is improved. Can be realized.

Further, since the joint portion contains the component (b) (e.g., precipitated and dispersed in a glass matrix in a conductive state), the reduction expansion coefficient is lowered, and therefore, in a reducing atmosphere (e.g., Even when exposed to a reducing atmosphere containing 5 vol% hydrogen (H ₂ ) and 95 vol% nitrogen (N ₂ ), expansion of the joint is suppressed and high stability (low reductive expansion) is exhibited.
Here, conventionally, since there is a side (part) exposed to the oxygen atmosphere and a side (part) exposed to the reducing atmosphere at the joint between the oxygen ion conductive ceramic material and the connecting member, oxygen ions are present. When the conduction module is operated, there is a possibility that the degree of expansion in the two parts is different and a crack is generated in the joint portion, thereby reducing the durability of the oxygen ion conduction module. However, according to the oxygen ion conduction module according to the present invention, the expansion on the reducing atmosphere side is greatly reduced in the above-mentioned joint portion, and the occurrence of cracks and the like is prevented, so that the durability (reduction expansion resistance) is improved. Can be realized.
Furthermore, it is preferable to use a perovskite oxide containing a highly conductive metal element as the component (b). Thereby, the conductivity under the above temperature range can be imparted to the joint. Therefore, according to the oxygen ion conduction module of the present invention, it is possible to realize a joint that can function as an electron conduction path.

Further, the cristobalite crystalline and / or leucite crystal is included in a number and a rate of less than 50 wt% than 3 wt% of the total the glass matrix.
When the content of the cristobalite crystal and / or the leucite crystal in the entire crystal-containing glass is within the above range, both the heat resistance and the air tightness at the joint can be achieved at a higher level.
And in one desirable mode of an oxygen ion conduction module indicated here, the glass mixed in the above-mentioned joined part is the following composition by mass ratio of oxide conversion:
SiO ₂ 60 to 75 wt%;
Al ₂ O ₃ 10-20% by mass;
Na ₂ O 3-10% by mass;
K ₂ O 5-15% by mass;
MgO 0 to 3% by mass;
CaO 0 to 3% by mass;
Is substantially composed of.
The joint where the crystal-containing glass having such a composition coexists has a thermal expansion coefficient that approximates the thermal expansion coefficient (thermal expansion coefficient) of the oxygen ion conductive ceramic material to be joined and the connection member. For this reason, the oxygen ion conduction module having the above-described configuration disclosed herein is repeatedly used in a high temperature range (for example, 800 ° C. to 1000 ° C.), and the temperature rises between the use temperature range and a temperature when not in use (room temperature). Even if the temperature and the temperature decrease are repeated, the leakage of gas from the joined portion (seal portion) between the oxygen ion conductive ceramic material and the connecting member can be prevented, and high airtightness can be maintained for a long time. Therefore, the oxygen ion conduction module having such a configuration can realize excellent heat resistance and airtightness (durability).

Further , the perovskite oxide has a general formula:
La _1-x A _x MO _3-δ (1)
(However, A is one or more elements selected from the group consisting of Sr, Ba, and Ca, and M is one or more metal elements that can form a perovskite structure. 0 ≦ x ≦ 1, and δ is a value determined so as to satisfy the charge neutrality condition.
More preferably, the perovskite oxide includes at least Fe as a metal element that can form a perovskite structure.
_{La 1-x A x M y} Fe 1-y O 3-δ (2)
(However, A is one or more elements selected from the group consisting of Sr, Ba, and Ca, and M is one or more metal elements that can form a perovskite structure. 0 ≦ x ≦ 1, 0.2 ≦ y <1, and δ is a value determined so as to satisfy the charge neutrality condition.
In the oxygen ion conduction module having such a configuration, since the perovskite oxide having the above composition is mixed in the joint portion, even if at least a part of the perovskite oxide is exposed to a reducing atmosphere in the joint portion, Expansion is effectively suppressed. Therefore, according to such an oxygen ion conduction module, excellent reduction expansion resistance, heat resistance, and long-term airtightness are realized. In addition, by using a perovskite oxide that includes Fe (iron) as M (a metal element that can form a perovskite structure) in the general formula (1) and is represented by the general formula (2), Since conductivity can be imparted, it is even more preferable. Examples of the perovskite oxide represented by the general formulas (1) and (2) include a perovskite oxide (LSZF) represented by the general formula: La _1-x Sr _x Zr _1-y Fe _y O ₃ -δ Oxides) and perovskite oxides (LSTF oxides) represented by La _1-x SrxTi _1-y Fe _y O _{3 -δ} .

In addition, any one of the oxygen ion conduction modules disclosed herein suitably functions as a solid oxide fuel cell (SOFC).
That is, in the oxygen ion conductive module that functions as an SOFC, the oxygen ion conductive ceramic material is a zirconia-based (eg, yttria stabilized zirconia (YSZ)) solid electrolyte. The ceramic connecting member is made of an perovskite oxide (for example, lanthanum (La) or lanthanum chromite oxide in which a part of chromium (Cr) is substituted or not substituted with an alkaline earth metal). It is a connector. Furthermore, the bonding material for bonding the oxygen ion conductive ceramic material and the connecting member acts as the interconnector.
In the oxygen ion conductive module having such a function, the oxygen ion conductive ceramic material as a solid electrolyte in a high temperature range of 800 ° C. to 1200 ° C. (preferably 800 ° C. to 1000 ° C.), which is a preferable use temperature range of the SOFC. And a connecting member as an interconnector have heat resistance and reduction expansion resistance as described above, and act as (a part of) the interconnector. Therefore, according to such an oxygen ion conduction module, there is a difference in the degree of expansion between the fuel electrode (reducing atmosphere) side and the air electrode (oxidizing atmosphere) side of the interconnector at the joint portion in the module, and the interconnector cracks. The above-mentioned joining portion can be formed without causing a suitable SOFC that is excellent in heat resistance, reduction expansion resistance, and airtightness and that does not deteriorate battery performance.

In a further preferred embodiment of the oxygen ion conduction module disclosed herein, the reduction expansion coefficient of the joint is 0.1% or less (typically 0.01% to 0.1%).
By providing a joint having such a reduction expansion coefficient, an oxygen ion conduction module that exhibits good reduction expansion resistance even when used in a reducing atmosphere can be provided. Here, the reduction expansion coefficient is the following equation (3), where E _R (%) is the thermal expansion coefficient under a reducing atmosphere (hydrogen gas), and E _A (%) is the thermal expansion coefficient under an air atmosphere. Given.
[{(1 + E _R / 100) − (1 + E _A / 100)} / (1 + E _A / 100)] × 100 (3)

In a further preferred embodiment of the oxygen ion-conducting device disclosed herein, wherein the thermal expansion coefficient of the bonding portion is ^{9 × 10 -6 / K~14 × 10} -6 / K.
Such a thermal expansion coefficient (average value between room temperature (25 ° C.) based on a general differential expansion method (TMA) and a temperature below the softening point of glass (for example, 450 ° C.)) is, for example, from zirconia-based materials such as YSZ. It approximates the thermal expansion coefficient of a connecting member made of an oxygen ion conductive ceramic material and a perovskite oxide (for example, lanthanum chromite oxide). Thereby, the oxygen ion conduction module which is excellent in the heat resistance and durability of a joint part (seal part), and also the reduction expansion resistance can be provided.

This invention provides the joining material which solves the said subject as another side surface. That is, the bonding material is a bonding material for bonding the oxygen ion conductive ceramic material constituting the oxygen ion conductive module and at least one ceramic connecting member. The bonding material disclosed herein is a glass containing SiO ₂ , Al ₂ O ₃ , Na ₂ O, and K ₂ O as essential constituents, and preferably containing at least one of MgO and CaO as additional constituents. In this case, cristobalite crystals and / or leucite crystals are precipitated in a glass matrix and a perovskite oxide is mixed. Particularly preferably,
(A) The following composition in mass ratio in terms of oxide:
SiO ₂ 60 to 75 wt%;
Al ₂ O ₃ 10-20% by mass;
Na ₂ O 3-10% by mass;
K ₂ O 5-15% by mass;
MgO 0 to 3% by mass;
CaO 0 to 3% by mass;
A glass substantially composed of: cristobalite crystals and / or leucite crystals precipitated in a matrix of the glass; and (b). At least one perovskite oxide is mixed.
More preferably, the cristobalite crystal and / or the leucite crystal is contained in a proportion of more than 3% by mass and less than 50% by mass of the entire glass matrix.
Here, in a preferred embodiment of such a bonding material, as a bonding material (seal material) in the form of a paste (also referred to as a slurry) containing as a main component a bonding material raw material containing the components (a) and (b). Provided.
By using the bonding material having such a configuration and bonding the oxygen ion conductive ceramic material and the connecting member, the bonding portion exhibits high stability (reduction expansion resistance) even in a reducing atmosphere, Excellent in mechanical strength and heat resistance. Therefore, according to such a bonding material, it is possible to provide a preferable oxygen ion conduction module having such a bonding portion.
Moreover, when the content of the cristobalite crystal and / or the leucite crystal in the entire component (a) (ie, the crystal-containing glass) is within the above range, the heat resistance and the air tightness at the joint are further increased. Both can be achieved at a high level.

The perovskite oxide is
General formula:
La _1-x A _x MO _3-δ (1)
(However, A is one or more elements selected from the group consisting of Sr, Ba, and Ca, and M is one or more metal elements that can form a perovskite structure. 0 ≦ x ≦ 1, and δ is a value determined to satisfy the charge neutrality condition.)
It is represented by
More preferably, the perovskite oxide includes at least Fe as a metal element that can form a perovskite structure.
General formula:
La _1-x A _x MyFe _1-y O _3-δ (2)
(However, A is one or more elements selected from the group consisting of Sr, Ba, and Ca, and M is one or more metal elements that can form a perovskite structure. 0 ≦ x ≦ 1, 0.2 ≦ y <1, and δ is a value determined so as to satisfy the charge neutrality condition.
In the bonding material having such a configuration, the perovskite oxide having the above composition is mixed in the crystal-containing glass (the above-described component (a)), so that the bonding material has excellent reduction expansion resistance. The formation of the joined portion is realized, and a suitable oxygen ion conduction module including such a joined portion is provided. Among such perovskite oxides, a bonding material in which a perovskite oxide containing Fe is mixed is even more preferable because it can further impart conductivity to the above-mentioned bonding portion.

The present invention also provides a method for joining an oxygen ion conductive ceramic material constituting an oxygen ion conductive module and at least one ceramic connecting member.
That is, the method provided by the present invention provides any bonding material disclosed herein, and applies the bonding material to the connection portion between the oxygen ion conductive ceramic material and the connection member; and The bonded portion that cuts off the gas flow of the bonding material at the connecting portion between the oxygen ion conductive ceramic material and the connecting member by firing the applied bonding material in a temperature range of 1000 ° C. or higher. Forming.
In the method having such a configuration, an oxygen ion conduction module having the above-described effects can be provided by firing the bonding material applied to the connection portion in a high temperature range of 1000 ° C. or higher.

  Therefore, according to another aspect of the present invention, an oxygen ion conductive ceramic material (for example, a zirconia-based material) and at least one ceramic (for example, a lanthanum chromite-based perovskite oxide) using the bonding material disclosed herein. Provided is a method for producing an oxygen ion conducting module, characterized in that a connecting member made of metal is joined by the joining method described above. Here, it is preferable that the firing temperature of the bonding material is equal to or higher than the operating temperature range (for example, 800 ° C. to 1000 ° C.) of the oxygen ion conduction module.

It is sectional drawing which shows typically flat type SOFC (single cell) as a typical example. It is the figure which showed typically the apparatus for exposing the sample of the samples (1)-(10) which concerns on the Example of this invention to an air atmosphere and a reducing atmosphere, and measuring leak generation | occurrence | production.

  Hereinafter, preferred embodiments of the present invention will be described. In addition, matters other than matters specifically mentioned in the present specification (for example, a method for preparing a glass component constituting a bonding material) and matters necessary for carrying out the present invention (mixing method of raw material powders and molding of ceramics) Method) can be understood as a design matter of those skilled in the art based on the prior art in the field. The present invention can be carried out on the basis of the contents first disclosed in the present invention and common technical knowledge in the field.

  In the oxygen ion conduction module of the present invention, the joint between the oxygen ion conductive ceramic material and the ceramic connecting member constituting the module is (a) cristobalite crystal and / or leucite crystal is precipitated in the glass matrix. It is characterized by being formed by a mixed material of the above-mentioned crystal-containing glass and (b) perovskite type oxide, and other components such as an oxygen ion conductive ceramic material and a ceramic connecting member The shape and composition of can be determined arbitrarily in light of various criteria. For example, in an oxygen separation device which is a typical example of such an oxygen ion conduction module, an oxygen ion conductive ceramic material which is a perovskite oxide is formed into a film shape and acts as an oxygen separation membrane material, and is similar to the membrane material. A porous connecting member mainly composed of magnesia, zirconia, silicon nitride, silicon carbide or the like is formed in a cylindrical shape and can act as a base material for the oxygen separation membrane material. Alternatively, in a fuel cell (typically SOFC) which is another typical example of the oxygen conduction module, an oxygen ion conductive ceramic material formed in a predetermined shape as a solid electrolyte is joined to a connecting member as an interconnector. By doing so, a stack can be configured.

The bonding material disclosed here is a bonding material for bonding the oxygen ion conductive ceramic material constituting the oxygen ion conductive module and at least one ceramic connecting member to each other as described above, and (a) and cristobalite (SiO ₂₎ crystals and / or leucite (KAlSi ₂ O ₆ or _{4SiO 2 · Al 2 O 3 ·} K 2 O) glass composition having a composition crystals can precipitate (crystal-containing glass) in a glass matrix, (B) A perovskite oxide is mixed and formed.

First, the crystal-containing glass that is the component (a) will be described.
When an oxygen ion conduction module typified by an oxygen separator or SOFC is used in a relatively high temperature range, for example, 800 to 1200 ° C., preferably 800 to 1000 ° C. (for example, 900 to 1000 ° C.), the component (a) As such, a glass having a composition that hardly melts in the high temperature range is preferable. In this case, a desired high melting point (high softening point) can be realized by adding or increasing a component that increases the melting point (softening point) of the glass.
Such component (a) is preferably an oxide glass containing SiO ₂ , Al ₂ O ₃ , and K ₂ O as essential components. In addition to these essential components, various components (typically various oxide components) can be additionally contained depending on the purpose.
Moreover, the amount of cristobalite crystals and / or leucite crystals deposited can be appropriately adjusted depending on the content (composition ratio) of the essential constituents in the glass composition. Here, the cristobalite crystal and / or the leucite crystal is more than 3 mass% and less than 50 mass% (more preferably 5 mass% to 45 mass%, for example, 10 mass) of the whole glass component (crystal-containing glass). % To 40% by mass) is preferably adjusted so as to be contained (precipitated). When the content of the crystal is 3% by mass or less, the water resistance and chemical resistance of the joint can be lowered. Further, when the content is 50% by mass or more, the joint portion may not be completely sealed and airtightness may be lost.
Is not particularly limited, the mass ratio of the oxide basis the total glass components (including cristobalite crystalline and / or leucite crystalline _portion), SiO 2: 60 to 75 _{wt%, Al} 2 O 3: _10~20 wt%, Na ₂ O: 3 to 10% by mass, K ₂ O: 5 to 15% by mass, MgO: 0 to 3% by mass, and CaO: 0 to 3% by mass (preferably 0.1 to 3% by mass) Is preferred.

SiO ₂ is a component constituting a cristobalite crystal and a leucite crystal, and is a main component constituting the skeleton of the glass layer (glass matrix) of the joint. If the SiO ₂ content is too high, the melting point (softening point) becomes too high, which is not preferable. On the other hand, if the SiO ₂ content is too low, the amount of cristobalite crystals and / or leucite crystals deposited is not preferred. In addition, water resistance and chemical resistance are reduced. Preferably SiO ₂ content of from 60 to 75% by weight of the total glass composition, and particularly preferably about 65% to 75%.

Al ₂ O ₃ is a component constituting a leucite crystal, and is a component involved in adhesion stability by controlling the fluidity of glass. If the Al ₂ O ₃ content is too low, the adhesion stability is lowered, which may impair the formation of a glass layer (glass matrix) having a uniform thickness, and the amount of leucite crystal precipitation decreases, which is not preferable. On the other hand, if the Al ₂ O ₃ content is too high, the chemical resistance of the joint may be lowered. It is preferable al ₂ O ₃ content is 10 to 20% by weight of the total glass composition.

K ₂ O is a component constituting the leucite crystal, and is a component that increases the coefficient of thermal expansion (thermal expansion coefficient) together with other alkali metal oxides (typically Na ₂ O). If the K ₂ O content is too low, the amount of leucite crystal precipitation is reduced, which is not preferable. Further, if the K ₂ O content and the Na ₂ O content are too low, the thermal expansion coefficient (thermal expansion coefficient) may be too low. On the other hand, if the K ₂ O content and the Na ₂ O content are too high, the thermal expansion coefficient (thermal expansion coefficient) becomes excessively high, which is not preferable. The K ₂ O content is preferably 5 to 15% by mass of the entire glass composition, and particularly preferably about 7 to 10%. Further, it is preferable (typically Na 2 _O) other alkali metal oxides is 3-10 wt% content of the total glass composition. It is particularly preferable that the total of K ₂ O and Na ₂ O is 10 to 20% by mass of the entire glass composition.

  MgO and CaO, which are alkaline earth metal oxides, are optional additives that can adjust the thermal expansion coefficient. CaO is a component that can increase the hardness of the glass layer (glass flux) and improve the wear resistance, and MgO is also a component that can adjust the viscosity during glass melting. Moreover, since a glass matrix is comprised by a multicomponent system by adding these components, chemical resistance can improve. The content of these oxides in the entire glass composition is preferably zero (no addition) or 3% by mass or less. For example, the total amount of MgO and CaO is preferably 2% by mass or less of the entire glass composition.

In addition to the above-described oxide components, components that are not essential in the practice of the present invention (for example, B ₂ O ₃ , ZnO, Li ₂ O, Bi ₂ O ₃ , SrO, SnO, SnO ₂ , CuO, Cu ₂ O). , it can be added according to the _{TiO 2, ZrO 2, La 2} O 3) a variety of purposes.
Preferably, the thermal expansion coefficient of the glass constituting the joint between the oxygen ion conductive ceramic material and the connecting member in the oxygen ion conductive module approximates the thermal expansion coefficient of the oxygen ion conductive ceramic material and the connecting member. The above-mentioned components are mixed to prepare crystal-containing glass (component (a)). For example, when the oxygen ion conductive ceramic material is a zirconia material such as YSZ and the connecting member is a perovskite oxide such as a lanthanum chromite oxide, it is formed by approximating these thermal expansion coefficients. The thermal expansion coefficient of the joint (room temperature (25 ° C.) based on the differential expansion method (TMA) to (average value between temperatures below the softening point of the glass (for example, 450 ° C.)) is 9 × 10 ⁻⁶ / K to 14 What is necessary is just to prepare the said crystal | crystallization containing glass by adjusting a composition so that it may become ^x10 < ^-6 > / K.

Next, the component (b) constituting the bonding material will be described.
The perovskite oxide as the component (b) hardly reacts with the crystal-containing glass under the operating temperature range (800 ° C. to 1200 ° C.) of the oxygen ion conduction module, and may be mixed in the crystal-containing glass. Even if the coefficient of thermal expansion does not depart from the above range and is placed under a reducing atmosphere (for example, a reducing atmosphere containing 5 vol% hydrogen (H ₂ ) and 95 vol% nitrogen (N ₂ )), the reducing atmosphere It is preferable that the exposed portion is difficult to expand (that is, one having high reduction expansion resistance).
Such perovskite oxides have the general formula:
La _1-x A _x MO _3-δ (1)
A perovskite oxide represented by Here, A is one or more elements selected from the group consisting of Sr, Ba and Ca. Sr is preferable. Further, “x” in the general formula (1) is a value indicating a ratio of La replaced by A in the perovskite structure. The possible range of x is 0 ≦ x ≦ 1 (preferably 0 ≦ x <1, for example, 0.4 ≦ x ≦ 0.6). M is one or more metal elements that can form a perovskite structure.
Here, δ is a value determined so as to satisfy the charge neutrality condition. The number of oxygen atoms in the general formula (1) varies depending on the type of atom that substitutes a part of the perovskite structure, the substitution ratio, and other conditions, so that it is difficult to display accurately. Therefore, it is appropriate to adopt a positive number δ (0 <δ <1) that does not exceed 1 as a value that is determined so as to satisfy the charge neutrality condition, and to display the number of oxygen atoms as 3-δ. However, for the sake of convenience, 3 is displayed below. However, even if the number of oxygen atoms is represented as 3 for convenience, it does not represent a different compound.

More preferably, the perovskite oxide represented by the general formula (1) as described above has conductivity (that is, can exist in a state having conductivity under the above temperature range). preferable. As such a perovskite oxide, a perovskite oxide containing Fe at the B site (that is, as an element constituting M in the general formula (1)) is preferable. This perovskite oxide has a general formula:
_{La 1-x A x M y} Fe 1-y O 3-δ (2)
It is represented by “Y” in the general formula (2) is a value indicating the ratio of M replaced by Fe at the B site of the perovskite structure. More preferably, the perovskite oxide represented by the general formula (2) further contains Zr (zirconium) and / or Ti (titanium) in addition to Fe at the B site. Examples of such an oxide include LSZF oxide and LSTF oxide. The inclusion of such Zr and / or Ti is preferable because the reduction expansion of the oxide can be suppressed and a low reduction expansion coefficient (high reduction expansion resistance) can be exhibited.
Fe and Zr are elements that can be included as a constituent material of a single cell in a general solid oxide fuel cell (SOFC) (for example, yttria-stabilized zirconia (YSZ) as an electrolyte material). For this reason, in the SOFC which is a typical example of the oxygen ion module according to the present invention, Fe and Fe are bonded to the joint between the zirconia solid electrolyte (oxygen ion conductive ceramic material) and the perovskite oxide (connection member). By applying a bonding material in which the perovskite oxide containing Zr is mixed as a constituent component (b), even if there is a possibility that such Fe and Zr may diffuse out of the bonded portion, the battery performance of the SOFC is deteriorated. Can be suppressed.

However, Zr and Ti provide reduction expansion resistance to the perovskite oxide, but may reduce conductivity. On the other hand, Fe provides conductivity to the perovskite oxide, but may increase the reduction expansion coefficient. Therefore, by changing the content of Fe and Zr (and / or Ti) at the B site, the reduction expansion resistance and conductivity of the bonding material containing the perovskite oxide represented by the general formula (2) can be improved. It is good to adjust with good balance.
As a result, in the perovskite oxide represented by the general formula (2) as a constituent (b) capable of providing both reduction expansion resistance and conductivity, the Zr of the B site in the general formula (2) If the molar ratio of (or Ti) and Fe is y: (1-y), the possible range of y is 0.2 ≦ y <1 (more preferably 0.2 ≦ y ≦ 0.5, for example, 0.2 ≦ y ≦ 0.4) is preferable.

  The content of the perovskite oxide (component (b)) is not particularly limited, but the bonding ability required for the bonding material (that is, depends on the content of the glass component), heat resistance, and reduction expansion resistance. In order to provide all of the properties (and also conductivity) at a high level, it is 40% by mass or more (more preferably 50% by mass or more, more preferably, based on the crystal-containing glass (component (a)). 50 wt% to 90 wt%, for example, 50 wt% to 80 wt%) is preferable.

The bonding material containing the crystal-containing glass and the perovskite oxide at such a content provides heat resistance (or durability against temperature change) to a bonding portion using the bonding material. Can do.
In addition, such a bonding material, the thermal expansion coefficient in air atmosphere (oxygen partial pressure of about 200 hPa (approximately 0.2 atm) and _{E A,} a reducing atmosphere (e.g., hydrogen _(H 2) 5 vol%, nitrogen _(N 2) the thermal expansion coefficient in a reducing atmosphere) containing 95 vol% as _{E R,} the following equation (3):
[{(1 + E _R / 100) − (1 + E _A / 100)} / (1 + E _A / 100)] × 100
It is possible to provide the joint with low reductive expansion (that is, high reductive expansion resistance) in which the reductive expansion coefficient given by (1) is 0.1% or less. Here, as the thermal expansion coefficients E _R and E _A , for example, values obtained by measuring an increase in volume between room temperature and 1000 ° C. can be used. A bonding material capable of giving such a reduction expansion coefficient to the joint can be realized by setting the values of x and y (especially the value of y) in the general formula (1) or (2) to the above-described preferable ranges. .

There is no particular limitation on the method for producing the bonding material having the above composition, and it is the same as that for producing a conventional crystal-containing glass (that is, a glass composition having a composition capable of depositing cristobalite crystals and / or leucite crystals). The method is used. Typically, compounds for obtaining various oxide components constituting the composition (for example, industrial products, reagents, various minerals containing oxides, carbonates, nitrates, complex oxides, etc., containing each component) Raw materials) and other additives as required are charged into a mixer such as a dry or wet ball mill at a predetermined blending ratio and mixed for several to several tens of hours.
The obtained admixture (powder) is dried, placed in a refractory crucible, and heated and melted under suitable high temperature (typically 1000 ° C. to 1500 ° C.) conditions.

Next, the obtained glass is crushed and subjected to crystallization heat treatment. For example, cristobalite is heated in the glass matrix by heating the glass powder from room temperature to about 100 ° C. at a heating rate of about 1 to 5 ° C./min and holding it in the temperature range of 800 to 1000 ° C. for about 30 to 60 minutes. Crystals and / or leucite crystals can be precipitated.
The leucite-containing glass thus obtained can be formed into a desired form by various methods. For example, a powdery glass composition (component (a)) having a desired average particle size (for example, 0.1 μm to 10 μm) can be obtained by pulverizing with a ball mill or appropriately sieving.

To the powdery glass composition thus obtained, the perovskite oxide as the component (b) is added at a blending ratio determined according to the desired reduction expansion coefficient, and then an appropriate amount of water is added. And using a ball mill similar to the above. Then, the powdery joining material which concerns on this invention can be obtained by implementing the drying process for predetermined time.
The powder-like bonding material thus obtained is typically prepared in a paste like the conventional bonding material, and is applied to the connecting portion between the oxygen ion conductive ceramic material and the connecting member. be able to. For example, a paste can be prepared by mixing an appropriate binder or solvent with the obtained bonding material. Note that the binder, solvent, and other components (for example, a dispersant) used in the paste are not particularly limited, and can be appropriately selected from conventionally known ones in paste production.
For example, a preferable example of the binder is cellulose or a derivative thereof. Specific examples include hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, carboxyethyl methyl cellulose, cellulose, ethyl cellulose, methyl cellulose, ethyl hydroxyethyl cellulose, and salts thereof. It is preferable that a binder is contained in 5-20 mass% of the whole paste.

  Examples of the solvent that can be contained in the paste include ether solvents, ester solvents, ketone solvents, and other organic solvents. Preferable examples include ethylene glycol and diethylene glycol derivatives, high-boiling organic solvents such as toluene, xylene and terpineol, or combinations of two or more thereof. Although the content rate of the solvent in a paste is not specifically limited, About 1-40 mass% of the whole paste is preferable.

  The bonding material disclosed here can be used in the same manner as a conventional bonding material of this type. Specifically, the oxygen ion conductive ceramic material to be bonded and the bonded portion of the connecting member are contacted and connected to each other, and a bonding material prepared in a paste form is applied to the connected portion. Then, the coated material made of the bonding material is dried at an appropriate temperature (typically 60 to 100 ° C.), and then the temperature range of 1000 ° C. or higher, preferably the operating temperature range of the oxygen ion conduction module (for example, 800 to 1000). When the temperature range where the glass does not flow out (for example, when the use temperature range is up to about 1000 ° C.) is typically higher than the temperature range, or higher than that, typically 800 ° C. to 1200 ° C. Baked at 1000 ° C. to 1200 ° C. and typically at 1200 ° C. to 1300 ° C. when the operating temperature range is approximately 1200 ° C. This forms a joint (seal part) that blocks gas flow (that is, there is no gas leak) at the connection part between the oxygen ion conductive ceramic material and the connection member. Even if such a joint is exposed to a reducing atmosphere in the above temperature range, the expansion of the exposed part is suppressed. Therefore, one of the causes of the occurrence of cracks in the joint between the oxygen ion conductive ceramic material and the connection member. The expansion difference between the reducing atmosphere side and the oxidizing atmosphere side is greatly reduced. That is, by using such a bonding material, the oxygen ion conductive ceramic material and the connecting member are bonded to each other, and an oxygen ion conductive module that realizes high durability over a long period of time by preventing the occurrence of cracks at the bonded portion is provided. can do.

An oxygen ion conduction module having a joint formed by using the joining material as described above will be described in detail by taking as an example a case where the module functions as an SOFC.
In such SOFC, the joint (sealing part) between the zirconia solid electrolyte (oxygen ion conductive ceramic material) and the interconnector (connecting member) made of lanthanum chromite oxide is used for the crystal-containing glass and the conductive substance. It is characterized by being formed by mixing. The shape and composition of other components such as the fuel electrode (anode) and the air electrode (cathode) can be arbitrarily determined in light of various standards.

As a solid electrolyte for constructing the SOFC disclosed herein, a dense layer having high oxygen ion conductivity and no gas permeability can be formed in both an oxidizing (air) atmosphere and a reducing (fuel gas) atmosphere. Consists of materials. As this suitable material, a zirconia-based solid electrolyte is used. Typically, zirconia (YSZ) stabilized with yttria (Y ₂ O ₃ ) is used. Other suitable zirconia-based solid electrolytes include zirconia (CSZ) stabilized with calcia (CaO), zirconia (SSZ) stabilized with scandia (Sc ₂ O ₃ ), and the like.

As an interconnector (separator) for constructing the SOFC disclosed herein, an oxygen supply gas (for example, air) and a fuel gas (for example, hydrogen (H ₂ )) are physically cut off and have electronic conductivity. Lanthanum chromite perovskite oxide (lanthanum chromite oxide) is used.
Such a lanthanum chromite oxide has a general formula: La _1-x Max _x Cr _1-y Mb _y O ₃
In the formula, Ma and Mb are one or two or more alkaline earth metals that are the same or different from each other, and x and y are 0 ≦ x <1 and 0 ≦ y <1, respectively. That is, the lanthanum chromite oxide may be lanthanum or a lanthanum oxide in which a part of chromium is substituted with an alkaline earth metal. Preferable examples include LaCrO ₃ or an oxide (lanthanum calcia chromite) in which Ma or Mb is calcium (Ca), such as La _0.8 Ca _0.2 CrO ₃ .

The fuel electrode and air electrode provided in the SOFC disclosed here may be the same as those of the conventional SOFC, and are not particularly limited. For example, nickel (Ni) and YSZ cermets, ruthenium (Ru) and YSZ cermets, and the like are preferably used as the fuel electrode. As the air electrode, a lanthanum cobaltate (LaCoO ₃ ) -based or lanthanum manganate (LaMnO ₃ ) -based perovskite oxide is preferably employed. Porous bodies made of these materials are used as a fuel electrode and an air electrode, respectively.

As the fuel gas used in such SOFC, instead of hydrogen, methane (CH _4), propane may be used hydrocarbons such as butane as the reformed gas. In such a case, oxygen ions O ²⁻ from the air electrode move in the solid electrolyte and reach the fuel electrode. At the fuel electrode, the hydrocarbon is reformed (reacted with water) to carbon monoxide (CO) or hydrogen (H ₂ ), so that CO and H ₂ react with the O ^{2− at the} fuel electrode. To get power.
In order to use such a fuel gas, the bonding material disclosed herein is preferably used even when manufacturing (constructing) an SOFC including a solid electrolyte or an interconnector made of a material different from the above. Can be used.

The manufacturing of the SOFC single cell and the stack thereof may be in accordance with the manufacturing of the conventional SOFC single cell and stack, and no special processing is required to construct the SOFC of the present invention. A solid electrolyte, an air electrode, a fuel electrode, and an interconnector can be formed by various methods conventionally used.
For example, a YSZ molded body formed by extrusion molding or the like using a molding material made of a predetermined material (for example, a YSZ powder having an average particle diameter of about 0.1 to 10 μm, a binder such as methyl cellulose, a solvent such as water) It calcinates in a suitable temperature range (for example, 1300-1600 degreeC) below, and produces the solid electrolyte of a predetermined shape (for example, plate shape or tubular shape).
A slurry for forming an air electrode made of a predetermined material (for example, the perovskite oxide powder having an average particle size of about 0.1 μm to 10 μm, a binder such as methyl cellulose, a solvent such as water) is applied to one surface of the solid electrolyte. Then, a porous film-like air electrode is formed by firing in an appropriate temperature range (for example, 1300 to 1500 ° C.) under atmospheric conditions.
Next, a fuel electrode is formed on the other surface of the solid electrolyte (surface not forming the air electrode) by an appropriate method using an atmospheric pressure plasma spraying method, a low pressure plasma spraying method, or the like. For example, the porous membrane fuel electrode made of the cermet material is formed by spraying the raw material powder melted by the plasma onto the surface of the solid electrolyte.

  Further, an interconnector having a predetermined shape can be produced by the same method as that for the solid electrolyte. For example, a molded body formed by extrusion molding or the like using a molding material made of a predetermined material (for example, a lanthanum chromite oxide powder having an average particle size of about 0.1 μm to 10 μm, a binder such as methyl cellulose, a solvent such as water) Firing is performed in an appropriate temperature range (for example, 1300 to 1600 ° C.) under atmospheric conditions to produce an interconnector having a predetermined shape (for example, a plate shape or a tubular shape).

Then, by using the bonding material according to the present invention, the interconnector produced as described above is bonded to a solid electrolyte, thereby manufacturing a single cell and a stack of SOFC, which is a typical example of the oxygen ion conduction module according to the present invention. be able to. For example, as schematically shown in FIG. 1, as a typical example of SOFC, an air electrode 14 is provided on one surface of a plate-shaped solid electrolyte (that is, an oxygen ion conductive ceramic material) 12, and a fuel electrode 16 is provided on the other surface. Can be provided, and a fuel cell (SOFC) 10 including interconnectors (that is, connection members) 18A and 18B joined to the solid electrolyte 12 via a joint (joining material) 20 can be provided. An oxygen supply gas (typically air) flow path 2 is formed between the air electrode 14 and the air electrode side interconnector 18A, and a fuel is provided between the fuel electrode 16 and the fuel electrode side interconnector 18B. A gas (hydrogen supply gas or hydrocarbon gas) flow path 4 is formed.
Note that the SOFC disclosed here is a single cell constituting the SOFC (for example, a single cell constituting unit including an interconnector previously joined to a solid electrolyte) or a single cell constituting the SOFC (typically Can include a SOFC stack in which a plurality of interconnectors in a state of being joined to a solid electrolyte that constitutes the single cell are stacked.

  EXAMPLES Examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the following examples.

<Example 1: Production of crystal-containing glass as component (a) of bonding material>
SiO ₂ powder, Al ₂ O ₃ powder, Na ₂ CO ₃ powder, K ₂ CO ₃ powder, MgCO ₃ powder, and CaCO ₃ powder having an average particle diameter of about 1 to 10 μm are respectively mixed with the following blending ratios, that is, oxides. 60-75 _{wt%, Al 2 O 3;;} SiO 2 in terms of 10 to 20 _wt%, Na 2 O; _{3~10 wt%, K} 2 O 3; _5~15 wt%, MgO; 0 to 3 wt% ; CaO; mixed at 0 to 3% by mass to prepare a raw material powder of the crystal-containing glass of the component (a).
Next, the raw material powder was melted in a temperature range of 1000 to 1500 ° C. (here, 1450 ° C.) to form glass. Thereafter, the glass was pulverized and subjected to a crystallization heat treatment in a temperature range of 800 to 1000 ° C. (here, 850 ° C.) for 30 to 60 minutes. As a result, cristobalite crystals and / or leucite crystals were precipitated so as to be dispersed in the glass matrix. Thereafter, the obtained crystal-containing glass was pulverized and classified to obtain a powdery crystal-containing glass A having an average particle size of about 2 μm. The ratio (content ratio) of cristobalite crystals and / or leucite crystals in the entire crystal-containing glass A was 20% by mass.
Similarly to the crystal-containing glass A, a crystal-containing glass B and a crystal are obtained using SiO ₂ powder, Al ₂ O ₃ powder, Na ₂ CO ₃ powder, K ₂ CO ₃ powder, MgCO ₃ powder, and CaCO ₃ powder. Containing glass C was produced. The content of cristobalite crystal and leucite crystal in the entire crystal-containing glass B was 3%. The content of cristobalite crystals and / or leucite crystals in the entire crystal-containing glass C was 50% by mass.
Further, commercially available heat resistant glass (Corning Heat Resistant Glass (PYREX (registered trademark)), hereinafter referred to as “Pyrex (registered trademark) glass”) was prepared.

<Example 2: Production of perovskite oxide as component (b) of bonding material>
Next, six types of perovskite oxides having different compositions were produced. (Oxides (1) to (6))
Commercially available lanthanum oxide (La ₂ O ₃ ) powder (average particle size about 2 μm), strontium carbonate (SrCO ₃ ) powder (average particle size about 2 μm), zirconium oxide (ZrO ₂ ) powder (average particle size about 1 μm) and oxidation Iron (Fe ₂ O ₃ ) powder (average particle size of about 2 μm) was mixed at a stoichiometric ratio of the composition of the fired body obtained after firing. In other words, La was 0.6, Sr was 0.4, Zr was 0.1, and Fe was 0.9 mol, and mixed using a ball mill. The mixed powder thus obtained was calcined at a firing temperature of 1200 ° C. for 6 hours. The calcined product thus obtained was pulverized by a wet ball mill to obtain a powdered oxide (1) (La _0.6 Sr _0.4 Zr _0.1 Fe _0.9 O ₃ ).
Other oxides (2) and (3) were obtained in the same manner as oxide (1).

As for the oxides (4) and (5), titanium oxide (TiO ₂ ) powder (average particle size of about 1 μm) is prepared instead of the zirconium oxide (ZrO ₂ ) powder, and is the same as the oxide (1). It was made.

As for the oxide (6), instead of the zirconium oxide (ZrO ₂ ) powder, chromium oxide (Cr ₂ O ₃ ) powder (average particle size of about 1 μm) is prepared, and the same as the oxide (1). Produced.
As described above, oxides (1) to (6) were obtained. Below, the composition of each oxide (1)-(6) is shown.
Oxide (1); La _0.6 Sr _0.4 Zr _0.1 Fe _0.9 O ₃
Oxide (2); La _0.6 Sr _0.4 Zr _0.2 Fe _0.8 O ₃
Oxide (3); La _0.6 Sr _0.4 Zr _0.3 Fe _0.7 O ₃
Oxide (4); La _0.6 Sr _0.4 Ti _0.1 Fe _0.9 O ₃
Oxide (5); La _0.6 Sr _0.4 Ti _0.3 Fe _0.7 O ₃
Oxide (6); La _0.6 Sr _0.4 Co _0.1 Fe _0.9 O ₃

Next, the crystal-containing glass A and the oxide (1) were mixed at a mass ratio of 1: 1 to prepare a sample (1).
Similarly, the crystal-containing glass A and the oxide (2) were mixed to prepare a sample (2). Thereafter, samples (3) to (6) were produced in the same manner.

Further, the Pyrex (registered trademark) glass and the oxide (2) were mixed at a mass ratio of 1: 1 to prepare a sample (7). Similarly, the Pyrex (registered trademark) glass and the oxide (5) were mixed to prepare a sample (8).
Further, the crystal-containing glass B and the oxide (5) were mixed at a mass ratio of 1: 1 to prepare a sample (9). The crystal-containing glass C and the oxide (5) were mixed at a mass ratio of 1: 1 to prepare a sample (10).

<Example 3: Preparation of a specimen having the same composition as the bonding material>
Next, 3 parts by mass of a general binder (here, ethyl cellulose was used) and 47 parts by mass of a solvent (here, terpineol was used) were mixed with 40 parts by mass of the sample (1). . This mixture was press-molded into a disk shape, dried at 80 ° C., and then fired in the air at a temperature range of 1000 to 1100 ° C. (here, 1050 ° C.) for 1 hour. In this way, three specimens of sample (1) were produced. Similarly, three samples (2) to (10) were prepared.
Here, for the samples (2), (3) and (5), the thermal expansion coefficient (however, an average value between room temperature (25 ° C.) and 450 ° C. based on the differential expansion method (TMA)). ) was in the range of either ^{9 × 10 -6 / K~14 × 10} -6 / K. Moreover, when the electrical conductivity under the temperature condition of 900 ° C. was determined by the DC four-terminal method for these three types of specimens, all were within the range of 0.01 S / cm to 10 S / cm.

<Example 4: Evaluation of reduction expansion coefficient>
Next, the reduction expansion coefficient was evaluated for each of the samples according to samples (1) to (10). In the sample according to sample (1), one of samples (1) was maintained from room temperature to 1000 ° C. in an air atmosphere (oxygen partial pressure of about 200 hPa (about 0.2 atm)). The increase in volume of the sample (1) in the temperature region was measured, and the increase was expressed as a percentage of the volume at room temperature. This was a thermal expansion coefficient E _A under an air atmosphere.
Similarly, a reducing atmosphere (hydrogen 5 vol%, containing 95 vol% of nitrogen) was determined thermal expansion coefficient _{E R} of the sample (1) under. These thermal expansion coefficients E _A and E _R was calculated reduction expansion of the sample (1) [%] by fitting to the equation (3).
For samples (2) to (10), the reduction expansion coefficient [%] was determined in the same manner as in the sample according to sample (1). These results are shown in Table 1. In addition, the "crystal content rate" described in Table 1 means the crystal component (that is, the crystal component glass A, B, or C as a constituent component of each of the samples (1) to (10) (that is, Cristobalite crystal and / or leucite crystal).
As a result, as shown in Table 1, the samples (2), (3), (5), and (7) to (10) have a high reduction resistance with a reduction expansion coefficient of 0.1% or less. Swellability was observed. On the other hand, in the samples (1) and (4), the reduction expansion coefficient exceeded 0.2%. In sample (6), cracks occurred immediately after measurement.

<Example 5: Evaluation of reduction durability>
Next, with respect to the specimens according to samples (1) to (10), air was exposed to one surface of each sample and methane (CH ₄ ) gas (fuel gas) was exposed to the other surface. By measuring whether or not it occurred, the durability (reduction durability) of each sample when exposed to a reducing atmosphere was evaluated. The evaluation method will be described with reference to FIG. FIG. 2 is a diagram schematically showing an apparatus for measuring the occurrence of leakage by exposing the specimens (1) to (10) formed in a disk shape to an air atmosphere and a reducing atmosphere. .
<Measurement device>
The measuring apparatus 100 includes a casing 30 that accommodates samples (1) to (10) (hereinafter also simply referred to as “sample 40”), and a heater 50 that maintains the sample 40 at a predetermined operating temperature. Is provided. The casing 30 includes an air electrode side outer tube 32 connected to one surface side of the sample 40, an air supply inner tube 34 inserted into the air electrode side outer tube 32, and the other surface side of the sample 40. It has a fuel electrode side outer tube 36 connected, and a fuel gas supply inner tube 38 inserted into the fuel electrode side outer tube 36. The inner pipes 34 and 38 and the outer pipes 32 and 36 are all formed of a dense ceramic (here, stabilized zirconia tube) such as alumina or mullite. A paste-like bonding material having the same composition as that of the sample 40 (that is, each of the paste-like samples (1) to (10)) is applied to the outer periphery of the sample 40, and one end of the outer tubes 32 and 36 and the sample 40 are connected to each other. Airtightly joined. On the one surface side of the sample 40, an air supply space 33 is defined by the sample 40 and the air electrode side outer tube 32. Further, a fuel gas supply space 37 is defined on the other surface side of the sample 40 by the sample 40 and the fuel electrode side outer tube 36.

The measuring apparatus 100 is configured such that the air supply inner pipe 34 is connected to an air supply means (not shown), and the air is supplied to the air supply space 33 through the air supply inner pipe 34. The measuring apparatus 100 is configured such that the fuel gas supply inner pipe 38 is connected to a fuel gas supply means (not shown), and the fuel gas is supplied to the fuel gas supply space 37 through the fuel gas supply inner pipe 38. Has been.
By setting the sample 40 in the measuring apparatus 100 having such a configuration, one surface of the sample 40 comes into contact with the air supplied to the air supply space 33, and the other surface of the sample 40 is fuel gas. The fuel gas supplied to the supply space 37 can be contacted.

<Measurement method>
Next, a measurement method will be described.
The sample 40 was set in the measurement apparatus 100, and air (oxygen partial pressure of about 200 hPa (about 0.2 atm)) was supplied to the air supply space 33 at a predetermined flow rate. In addition, methane (CH ₄ ) gas was supplied to the fuel gas supply space 37 at a predetermined flow rate. In this state, the temperature of the measuring apparatus 100 (sample 40) is maintained at 900 ° C. for 10 hours, and then the composition of the gas discharged from the fuel gas supply space 37 is measured by a gas chromatograph. It was measured whether or not oxygen (O ₂ ) gas supplied as a component was contained (that is, whether or not O ₂ gas was leaking).
Measurement was performed for each of the samples (1) to (10) as described above. The results are shown in Table 1. Note that “leak generation” in Table 1 means that the measurement apparatus 100 is 1000 times the O ₂ gas content measured when air and fuel gas are supplied before the measurement apparatus 100 is heated. This refers to the case where the O ₂ gas content measured when maintained at ° C. has increased by 3% or more.

  As a result, as shown in Table 1, the occurrence of leakage was observed in the samples according to samples (1), (4), (6), (9) and (10).

<Example 6: Evaluation of durability at room temperature cooling>
Next, when the specimens (samples 40) according to the samples (1) to (10) were cooled at a temperature decrease rate of 100 ° C. per hour from a temperature of 900 ° C. in the measuring apparatus 100, gas leaks in the sample 40 A test for confirming the presence or absence of water was conducted to evaluate the durability during cooling. At this time, the presence or absence of elution of the sample 40 and the presence or absence of cracks were also visually observed. The results are shown in Table 1. Note that “leak generation” in Table 1 has the same definition as above.
As a result, the samples (2), (3) and (5) had no cracks and no elution. Moreover, no gas leak occurred. On the other hand, the samples (1), (4), and (6) had cracks and leaks. Sample elution of the samples (7) to (9) was also observed. For the sample (10), the joint between the specimen and the outer tubes 32 and 36 joined by the paste-like joining material according to the sample (10) cannot be joined (sealed) in an airtight manner. Gas leaked from the joint.

  As described above, by using the bonding material according to the present embodiment, the reduction expansion coefficient is low (that is, the reduction expansion resistance is high), the resistance to temperature change is high (heat resistance is high), and the conductivity is improved. Can also be formed. Therefore, according to such a bonding material, it is possible to provide an oxygen ion conduction module provided with a preferable bonding portion as described above.

2 Oxygen supply gas flow path 4 Fuel gas flow path 10 SOFC
12 Solid Electrolyte 14 Air Electrode 16 Fuel Electrode 18A, 18B Interconnector 20 Joint (Joint)
30 casing 32 air electrode side outer tube 33 air supply space 34 air supply inner tube 36 fuel electrode side outer tube 37 fuel gas supply space 38 fuel gas supply inner tube 40 sample 50 heater 100 measuring device

Claims (7)

An oxygen ion conduction module comprising a ceramic material having oxygen ion conductivity,
The oxygen ion conductive ceramic material is bonded to at least one ceramic connecting member,
The joint between the oxygen ion conductive ceramic material and the connecting member has the following two components: (a). A glass characterized in that cristobalite crystals and / or leucite crystals are precipitated in the glass matrix in a proportion of more than 3% by weight and less than 50% by weight of the whole glass matrix ; and (b). At least one perovskite oxide represented by the following general formula (2) :
_{La 1-x A x M y} Fe 1-y O 3-δ (2)
(However, A is one or more selected from the group consisting of Sr, Ba and Ca.
M is Zr and / or Ti, 0 ≦ x ≦ 1, 0.2 ≦ y <1, and δ is a value determined to satisfy the charge neutrality condition. )
Oxygen ion conduction module that is formed in a mixture. The glass mixed in the joint is
The following composition in mass ratio in terms of oxide:
SiO ₂ 60 to 75 wt%;
Al ₂ O ₃ 10-20% by mass;
Na ₂ O 3-10% by mass;
K ₂ O 5-15% by mass;
MgO 0 to 3% by mass;
CaO 0 to 3% by mass;
The oxygen ion conduction module according to claim 1, substantially consisting of: The oxygen ion conduction module according to claim 1 or 2 , wherein a reduction expansion coefficient of the joint is 0.1% or less. Thermal expansion coefficient of the joining portion is ^{9 × 10 -6 / K~14 × 10} -6 / K, the oxygen ion-conducting device according to any one of claims 1-3. A bonding material for bonding an oxygen ion conductive ceramic material constituting an oxygen ion conductive module and at least one ceramic connecting member, the following two components:
(A). The following composition in mass ratio in terms of oxide:
SiO ₂ 60 to 75 wt%;
Al ₂ O ₃ 10-20% by mass;
Na ₂ O 3-10% by mass;
K ₂ O 5-15% by mass;
MgO 0 to 3% by mass;
CaO 0 to 3% by mass;
Glass cristobalite crystals and / or leucite crystals precipitated in the glass matrix in a proportion of more than 3% by weight and less than 50% by weight of the whole glass matrix. Glass; and (b). At least one perovskite oxide represented by the following general formula (2) :
_{La 1-x A x M y} Fe 1-y O 3-δ (2)
(However, A is one or more elements selected from the group consisting of Sr, Ba and Ca, M is Zr and / or Ti, 0 ≦ x ≦ 1, (2 ≦ y <1, and δ is a value determined to satisfy the charge neutrality condition.)
A joint material that is formed in a mixture. A method of joining an oxygen ion conductive ceramic material constituting an oxygen ion conductive module and at least one ceramic connecting member,
Preparing the bonding material according to claim 5 , and applying the bonding material to a connection portion between the oxygen ion conductive ceramic material and the connection member;
By firing the applied bonding material in a temperature range of 1000 ° C. or higher, a bonding portion that blocks gas flow composed of the bonding material at the connection portion between the oxygen ion conductive ceramic material and the connection member is provided. Forming,
Including the method. An oxygen ion-conducting device according to any one of claims 1-4,
The oxygen ion conductive ceramic material is a zirconia solid electrolyte,
The ceramic connecting member is an interconnector made of a perovskite oxide,
The oxygen ion conductive module functioning as a solid oxide fuel cell, wherein a bonding material for bonding the oxygen ion conductive ceramic material and the connecting member acts as the interconnector.

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