JP5290088B2 - Joining material for solid oxide fuel cell and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bonding material for a solid-oxide fuel cell used for forming a bonding part which has a high heat resistance and which is airtightly bonded in a high-temperature region (for example, 1,200&deg;C to 1,300&deg;C) of which temperature is higher than an operation temperature of the solid-oxide fuel cell; and to provide a method of manufacturing the same. <P>SOLUTION: The bonding material 40 is used for the solid-oxide fuel cell having glass as a main component. In the glass to constitute this bonding material, at least forsterite crystal is precipitated in a glass matrix, or magnesium oxide crystal and at least one selected from cristobalite crystal, leucite crystal, and the forsterite crystal are precipitated in the glass matrix. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a bonding material for a solid oxide fuel cell (SOFC) and a method for manufacturing the same.

  A solid oxide fuel cell (hereinafter sometimes referred to simply as “SOFC”) is also called a third generation fuel cell, and has the following advantages over other fuel cells. There is. For example, in SOFC, since the operating temperature can be increased, a reaction accelerator (catalyst) is unnecessary, and the running cost is reduced. Further, by reusing the high-temperature exhaust gas (exhaust heat), the overall efficiency (total efficiency) can be increased. Furthermore, since the SOFC has a high output density, it can be miniaturized. From these facts, it is expected as a distributed power generation apparatus that replaces an internal combustion engine such as a steam turbine or a gas turbine.

As a basic structure (single cell), SOFC has a porous structure on one surface of a dense solid electrolyte (for example, a dense membrane layer) made of an oxygen ion conductor (typically an oxygen ion conductive ceramic body). An air electrode (cathode) is formed, and a fuel electrode (anode) having a porous structure is formed (for example, laminated) on the other surface. 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. Further, in order to supply such a gas to both electrodes of the SOFC, a gas pipe that connects the gas source and the SOFC and distributes the respective gases is connected to the SOFC.

  As a solid electrolyte for SOFC, a solid electrolyte made of a zirconia-based material (for example, yttria stabilized zirconia: YSZ) is widely used because of its high chemical stability and mechanical strength. As the solid electrolyte (layer) becomes thinner, the ion permeation rate increases and the battery performance such as charge / discharge characteristics is improved. As a result, in recent years, an anode-supported SOFC in which a solid electrolyte is formed in the form of a thin film on the surface of a porous substrate that functions as a fuel electrode for the purpose of thinning the solid electrolyte to improve the battery performance of the SOFC. Development is underway.

For example, a cermet of NiO and zirconia is often used as the fuel electrode, and an oxide having a perovskite structure such as LaCoO ₃ or LaMnO ₃ is often used as the air electrode. These SOFC constituent materials such as electrolyte materials and electrode materials take into consideration the temperature characteristics that the SOFC normally operates in a high temperature range of about 800 ° C. to 1200 ° C., and also provide chemical durability in an oxidizing / reducing atmosphere at high temperatures. Improvement and development of a more preferable SOFC component material are being promoted for the purpose of improving battery performance, with high electrical conductivity selected and also close thermal expansion coefficients.

  In recent years, SOFC has been put into practical use, and as a result of the improvement in SOFC battery performance (power generation performance) with the thinning of the solid electrolyte and the improvement of the SOFC constituent materials as described above, there has been no problem in the past. Has come to influence the operating characteristics of SOFC. The main element is a gas leak in SOFC (for example, a joint between a single cell and a gas pipe, a joint between single cells, or a joint between an interconnector (also referred to as a separator) disposed between single cells and a single cell). This may be caused by gas leakage at the part. For example, the fuel gas utilization efficiency is reduced due to such a gas leak, and local heat distribution unevenness occurs. An SOFC having such a structure that may cause a poor airtightness is not preferable for practical long-term use, and it is a major problem to prevent the occurrence of gas leakage and improve the airtightness (sealability) of the joint in the SOFC. It has become.

Here, various bonding materials that can be adapted to the objects to be bonded have been proposed as bonding materials for bonding portions in SOFC. For example, Patent Document 1 describes a bonding material made of a mixture of stabilized zirconia and glass. Patent Document 2 describes a bonding material obtained by mixing a solid electrolyte constituent material and a separator constituent material. Patent Document 3 describes a sealing liquid mainly composed of ultrafine oxide having a melting point higher than the operating temperature of the solid oxide fuel cell. Patent Document 4 includes a sealing material for a fuel cell that can be used at a service temperature of 1000 ° C. or less, and includes a filler material such as MgO—MgAl ₂ O ₄ or stabilized zirconia dispersed in a glass matrix. Sealing materials have been proposed. Patent Document 5 proposes a solid oxide fuel cell sealing material comprising a mixed powder obtained by mixing glass powder containing silicon as a constituent element, magnesium oxide powder, and magnesium silicate powder.

JP-A-5-330935 JP-A-9-129251 Japanese Patent Laid-Open No. 11-154525 JP 2000-235862 A JP 2007-149430 A

In the junction in the conventional single cell, for example, about 7 × 10 ⁻⁶ K ⁻¹ to 15 × 10 ⁻⁶ K ⁻¹ (typically 9 × 10 ⁻⁶ K ^{−1 to} 14 × 10 ⁻⁶ K ^−1). ) Having a thermal expansion coefficient comparable to that of the cell constituent member (including members such as gas pipes that can be joined to a single cell made of such a cell constituent member). A joining material capable of forming a joint that can be used has been used.
In recent years, various cell constituent materials have been used for the purpose of improving SOFC performance, and are higher than the operating temperature of the SOFC (typically 800 ° C. to 1200 ° C.) (1200 ° C. or higher, for example, 1200 ° C.). It has become necessary to join the cell constituent materials by heat treatment at a temperature of ˜1300 ° C.). From this, for example, the strength (heat resistance) and airtightness (heat resistance) that can sufficiently withstand the heat treatment, which is a joint that can have a thermal expansion coefficient comparable to that of the cell component even under high temperature conditions such as 1200 ° C. or higher It has been desired to form a joint that can realize a high level of sealing performance.
However, conventional bonding materials as described in the above-mentioned patent documents are still not sufficient in terms of achieving both high heat resistance and high airtightness.

  This invention is made | formed in view of this point, The main objective has high heat resistance in the high temperature more than the operating temperature (for example, 800 to 1200 degreeC) of a solid oxide fuel cell. It is an object of the present invention to provide a bonding material for a solid oxide fuel cell used for forming an airtightly bonded joint. Another object is to provide a method for producing such a bonding material.

In order to achieve the above object, the bonding material of one aspect provided by the present invention is a bonding material for a solid oxide fuel cell mainly composed of glass. The glass is a glass in which at least forsterite crystals are precipitated in a glass matrix. The glass contains the following six constituent elements (essential constituent elements Si, Al, Na, K and optional constituent elements Ca, B), and 100 masses of the total of the six constituent elements in terms of oxides. The following mass composition as%:
SiO ₂ 60 to 78 wt%;
Al ₂ O ₃ 10~22% by weight;
Na ₂ O 3-16% by mass;
K ₂ O 5-16% by mass;
CaO 0 to 4% by mass;
B ₂ O _{30 to} 4% by mass;
Have. Here, the glass further includes Mg as a constituent element, and the mass composition of MgO is 3% by mass or more and less than 13% by mass in terms of oxide (MgO conversion) with the entire glass being 100% by mass, At least half of this amount is present as a constituent of crystals precipitated in the glass matrix.
In the description of the technical scope of the present invention, the numerical range using “to” is a range including the left and right numerical values of “to” (that is, the numerical range “A to B” is not less than A and not more than B). ).

Such an SOFC bonding material is a glass in which at least forsterite crystals (Mg ₂ SiO ₄ ) are precipitated in a glass matrix (for example, glass in which fine crystals of forsterite are precipitated in a dispersed state in a glass matrix, or a glass composition) It is a glass bonding material mainly composed of a material. As described above, in the crystal-containing glass constituting such a bonding material, magnesium (Mg) contained in the glass is 3% by mass to 13% by mass of the whole glass containing MgO in terms of oxide (in terms of MgO). It is contained in less than the mass composition, and at least half of this constitutes forsterite crystals and precipitates. Such a SOFC bonding material is composed of the above composition and contains at least forsterite crystals as a crystal component, so that the bonding material can be used in the SOFC operating temperature range (for example, 800 ° C. to 1200 ° C.) or higher. Even when exposed to a high temperature range (1200 ° C. or higher, for example, 1200 ° C. to 1300 ° C., preferably 1200 ° C. to 1400 ° C.), dissolution of crystals precipitated in the bonding material is preferably prevented and hardly flows. . In addition, forsterite crystals precipitated in the glass matrix, or crystals that can be precipitated in the glass matrix together with the forsterite crystals, such as cristobalite (SiO ₂ ) crystals, leucite (KAlSi ₂ O ₆ ) crystals, etc. In addition, since it is an insulator having neither ionic conductivity nor conductivity, the preferred embodiment as the crystal-containing glass may have complete insulation.
Therefore, according to the present invention, even when the temperature reaches the above high temperature range (particularly 1200 ° C. or more, for example, 1200 ° C. to 1300 ° C., preferably 1200 ° C. to 1400 ° C.), the junction (for example, the SOFC cell and the cell) There is no risk of elution from the junction with the interconnector to be electrically connected, or the junction between the SOFC (single) cell and the gas pipe that supplies the gas to the cell, and the heat resistance of the junction is improved. It is possible to provide a bonding material having the above-described configuration. In addition, it is possible to form a bonding portion having insulating properties by preferably bonding the portion where it is desired to avoid ionic conduction or electronic conduction by using such a bonding material.
Further, the bonding material according to this aspect has flexibility even in the above temperature range. Therefore, according to such a bonding material, even if a stress is generated in a bonded portion formed using the bonding material, the stress can be relaxed to suppress the occurrence of cracks, peeling, and the like. An improvement in the mechanical strength of the joint can be realized.
Here, “fuel cell (specifically, SOFC)” is a term including a single cell having a fuel electrode, an air electrode, and a solid electrolyte as constituent elements, and a so-called stack including a plurality of such single cells.

Further, the bonding material for a solid oxide fuel cell according to another aspect provided by the present invention is a bonding material for a solid oxide fuel cell mainly composed of glass, and the glass is a glass matrix. A glass in which a crystal made of magnesium oxide (MgO) and at least one crystal selected from a cristobalite crystal, a leucite crystal and a forsterite crystal are precipitated. The glass is composed of the following six constituent elements (essential constituent elements Si, Al, Na, K and optional constituent elements Ca, B), and the total of the six constituent elements is 100 mass in terms of oxides. The following mass composition as%:
SiO ₂ 60 to 78 wt%;
Al ₂ O ₃ 10~22% by weight;
Na ₂ O 3-16% by mass;
K ₂ O 5-16% by mass;
CaO 0 to 4% by mass;
B ₂ O _{30 to} 4% by mass;
Have. Here, the glass further has Mg as a constituent element, and the total composition of the glass is 100% by mass in terms of oxide, and the mass composition of MgO is 13% by mass to 30% by mass. Half of the amount is present as a constituent of the crystals precipitated in the glass matrix.
The solid oxide fuel cell (SOFC) bonding material according to the present embodiment is a glass in which at least one of cristobalite crystal, leucite crystal, and forsterite crystal is precipitated in addition to crystals made of MgO in a glass matrix. It is a glass bonding material mainly composed of (glass composition). In such crystal-containing glass, Mg contained in the glass is contained in a mass composition of 13% by mass or more and 30% by mass or less of the entire glass containing MgO in terms of oxide, and at least half of this constitutes Mg. It can be precipitated as a constituent component of the element crystal (mainly MgO crystal and forsterite crystal). When such a bonding material is composed of the above composition and contains the crystal component, the bonding material can be used in a SOFC operating temperature range (for example, 800 ° C. to 1200 ° C.) and higher (for example, 1200 ° C. or higher, for example, Even when exposed to a high temperature range of 1200 ° C. to 1300 ° C. (preferably 1200 ° C. to 1400 ° C.), dissolution of crystals precipitated in the bonding material is preferably prevented and hardly flows. Moreover, since the said crystal | crystallization including MgO crystal | crystallization is an insulator which has neither ionic conductivity nor electroconductivity, the said crystal | crystallization containing glass has perfect insulation.
Therefore, according to the bonding material according to this aspect, even when the temperature reaches the above high temperature range (particularly 1200 ° C. or more, for example, 1200 ° C. to 1300 ° C., preferably 1200 ° C. to 1400 ° C.), the bonding material is used. While there is no possibility that the formed joint portion is eluted, since it has flexibility, it is possible to realize improvement in heat resistance and mechanical strength of the joint portion. Further, according to such a bonding material, it is possible to realize formation of a bonding portion having insulating properties.

In a more preferable aspect of the solid oxide fuel cell bonding material of each of the above aspects disclosed herein, the coefficient of thermal expansion is 9 × 10 ⁻⁶ K ⁻ even after being exposed to a temperature of at least 1200 ° C. It is prepared so as to maintain a ^{1 ~13} × ¹⁰ -6 ^{K -1.}
Such a coefficient of thermal expansion (typically an average value between room temperature (25 ° C.) and 500 ° C. based on a general differential expansion method (TMA)) is, for example, an electrode (for example, fuel electrode) material, a solid electrolyte material, or It approximates the thermal expansion coefficient of a zirconia-based oxide (zirconia-based material) such as YSZ that can be suitably used as a gas pipe material or a lanthanum chromite-based oxide that can be suitably used as an interconnector material. Further, such a thermal expansion coefficient can be approximated to the thermal expansion coefficient of the entire SOFC cell or the entire SOFC system including the SOFC cell and the gas pipe. As a result, the SOFC having a joint formed using such a joining material is heated and lowered between the above operating temperature range (for example, 800 ° C. to 1200 ° C.) and a temperature when not in use (room temperature). Even when used repeatedly or exposed to high temperatures above the above operating temperature range, gas leakage from the joint (seal part) is prevented, and high airtightness and machinery over the long term Strength can be maintained. Moreover, the battery performance of the SOFC can be improved by preventing gas leakage.
Therefore, by using the bonding material having such a configuration, the air-tightness and the mechanical strength having the thermal expansion coefficient are obtained even after being exposed to a high temperature range of at least 1200 ° C. (typically higher). A joint (seal) that can be maintained at a high dimension can be formed, and a high-performance SOFC (system) including such a joint can be provided.

Moreover, this invention provides a solid oxide fuel cell (SOFC) provided with the junction part formed using the above joining materials as another side surface. That is, an SOFC including a plurality of cells including a fuel electrode, an air electrode, and a solid electrolyte, and an interconnector disposed and joined between the cells to electrically connect the plurality of cells. The joint between the cell and the interconnector is formed of any of the joining materials disclosed herein.
In the SOFC according to the present invention, since the cell and the interconnector are bonded using the bonding material, the operating temperature range of the SOFC (for example, 800 ° C. to 1200 ° C.) and higher (for example, 1200 ° C. or higher, for example, 1200 ° C. to Even when exposed to a high temperature range of 1300 ° C. (preferably 1200 ° C. to 1400 ° C.), the joint between the cell and the interconnector can maintain high airtightness and mechanical strength. Therefore, according to the SOFC according to the present invention, a high-performance SOFC excellent in heat resistance and battery characteristics is realized.

The present invention also provides a solid oxide fuel cell (SOFC) system including a joint formed using any of the joint materials disclosed herein. That is, the SOFC system includes an SOFC including one or a plurality of cells including a fuel electrode, an air electrode, and a solid electrolyte, and a gas pipe that is joined to the SOFC and supplies gas to the SOFC. Thus, the joint portion between the SOFC and the gas pipe is formed of any of the joining materials disclosed herein.
In the SOFC system according to the present invention, since the SOFC and the gas pipe are bonded using the bonding material, the operating temperature range of the SOFC (for example, 800 ° C. to 1200 ° C.) or higher (1200 ° C. or higher, for example, 1200 ° C.). Even when exposed to a high temperature range of ˜1300 ° C., preferably 1200 ° C. to 1400 ° C., the joint between the SOFC and the interconnector can maintain high hermeticity and mechanical strength. Therefore, according to the SOFC system according to the present invention, a high-performance SOFC system excellent in heat resistance and battery characteristics is realized.

Moreover, this invention provides the method of manufacturing the joining material for solid oxide fuel cells (SOFC) as another side surface. One aspect of the method for producing a bonding material for SOFC disclosed herein includes the following steps. That is, this manufacturing method has 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 3-15% by mass;
K ₂ O 5-15% by mass;
CaO 0 to 3% by mass;
B ₂ O _{30 to} 3% by mass;
MgO 0 to 3% by mass;
A glass raw material powder prepared substantially from the above is prepared, the raw material powder is melted to prepare a glass, the prepared glass is pulverized, and then the MgO powder is added to 3 of the whole glass raw material powder. A mixed powder of the glass and the MgO is prepared by adding in an amount corresponding to not less than 10% by mass and less than 10% by mass, and a crystal component is incorporated into the glass matrix by crystallizing the mixed powder. Including precipitation of at least forsterite crystals.
In such a production method, before carrying out the crystallization treatment for precipitating a crystal component in the glass matrix, MgO powder (mainly as Mg capable of constituting a crystal) is used separately from MgO that can constitute the glass matrix in advance. By adding to glass, at least forsterite crystals can be precipitated from the mixed powder.
Further, the bonding material obtained by such a method is, for example, 1200 ° C. or higher (typically 1200 ° C. to 1300 ° C., preferably 1200 ° C.), compared to the bonding material obtained by adding MgO powder after the crystallization treatment. The thermal expansion coefficient can be maintained within the range of 9 × 10 ⁻⁶ K ^{−1 to} 13 × 10 ⁻⁶ K ⁻¹ even in a high temperature range of ˜1400 ° C. or higher), so the constituent material of SOFC, etc. The thermal expansion coefficient can be approximated, and can be preferably used as a bonding material for SOFC. Therefore, according to such a joining method, it is possible to provide a joining material suitable as a joining material for SOFC capable of forming a joined portion having high airtightness and mechanical strength even under a high temperature range and having an insulating property. Can do.

Moreover, in another preferable one aspect | mode of the manufacturing method of the joining material for SOFC disclosed here, the following processes are included. That is, this manufacturing method has 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 3-15% by mass;
K ₂ O 5-15% by mass;
CaO 0 to 3% by mass;
B ₂ O _{30 to} 3% by mass;
MgO 0 to 3% by mass;
A glass raw material powder prepared so as to be substantially constituted is prepared, and the raw material powder is melted to prepare a glass. After the prepared glass is pulverized, the MgO powder is added to 10% of the whole glass raw material powder. A mixed powder of the glass and MgO is prepared by adding in an amount corresponding to not less than 30% by weight and not more than 30% by weight, and a crystal component is incorporated into the glass matrix by crystallizing the mixed powder. And precipitating a crystal made of magnesium oxide (MgO) and at least one crystal selected from a cristobalite crystal, a leucite crystal and a forsterite crystal.
In such a production method, the crystals can be simultaneously precipitated in the glass matrix, and a bonding material made of such a crystal-containing glass can be suitably produced. Moreover, since the joining material obtained by this method can maintain the thermal expansion coefficient within a range of 9 × 10 ⁻⁶ K ^{−1 to} 13 × 10 ⁻⁶ K ⁻¹ even in a high temperature range of, for example, 1200 ° C. or higher. It can be approximated by the coefficient of thermal expansion of the constituent material of SOFC, and can be preferably used as a joining material for SOFC. Therefore, according to such a manufacturing method, it is possible to provide a bonding material suitable as a bonding material for SOFC capable of forming a bonding portion having high hermeticity and mechanical strength even under a high temperature range and capable of forming a bonding portion having an insulating property. Can do.

In a further preferred aspect of the method for producing a SOFC bonding material of each aspect disclosed herein, as the crystallization treatment, the mixed powder is used in a temperature range (typically 1000 ° C. or lower, which can induce crystallization). For example, the heating may be performed at an appropriate predetermined time (for example, in the temperature range of 800 ° C. to 1000 ° C. for 30 minutes to 60 minutes) at 800 ° C. to 1000 ° C.
According to such a manufacturing method, by performing crystallization treatment under the above-described conditions, a bonding material made of crystal-containing glass in which various crystals are precipitated in a glass matrix, which is more suitable as a bonding material for SOFC, can be obtained. Can be realized.

  Moreover, the solid oxide fuel cell (SOFC) bonding material according to the present invention is preferably manufactured suitably by any of the manufacturing methods disclosed herein.

It is sectional drawing which shows typically one form of SOFC provided with the flat type cell and the interconnector joined to this cell. It is sectional drawing which shows typically one form of SOFC system provided with the anode support type solid oxide fuel cell and the gas pipe joined to this cell.

  Hereinafter, preferred embodiments of the present invention will be described. In addition, matters other than the matters specifically mentioned in the present specification (for example, the method for preparing the crystal-containing glass constituting the bonding material) and the matters necessary for carrying out the present invention (the raw material powder mixing method and the single cell) And a stack construction method) can be grasped as a design matter of a person skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

As described above, the bonding material of one aspect disclosed herein (hereinafter sometimes referred to as “first bonding material”) includes at least a forsterite crystal in the glass matrix. It is characterized by being precipitated glass (hereinafter sometimes referred to as “crystal-containing glass 1”). Further, in such the bonding material, the crystal-containing glass 1, Si, Al, Na, K, Ca, six of the constituent elements of B, SiO ₂ is the entire said six constituent element as 100 mass% in terms of oxide 60 to 78 wt%, _Al 2 _{O 3} is 10 to 22 wt%, Na ₂ O is 3 to 16 wt%, _{K 2} O is 5 to 16 wt%, CaO 0 to _4% by _weight, B 2 _{O 3} It has a mass composition of 0 to 4% by mass, the glass further has Mg as a constituent element, and the mass composition of MgO in terms of oxide is 3% by mass or more and 13% by mass with 100% by mass of the whole glass. In addition to being less than mass%, half of the amount is present as a constituent component of crystals precipitated in the glass matrix.

In another embodiment of the bonding material disclosed herein (hereinafter sometimes referred to as “second bonding material”), the glass constituting the bonding material is made of magnesium oxide (MgO) in a lath matrix. By being a glass in which at least one of a cristobalite crystal, a leucite crystal and a forsterite crystal is precipitated (hereinafter sometimes referred to as “crystal-containing glass 2”). It can be characterized. Further, in such the bonding material, the crystal-containing glass 2, Si, Al, Na, K, Ca, six of the constituent elements of B, SiO ₂ is the entire said six constituent element as 100 mass% in terms of oxide 60 to 78 wt%, _Al 2 _{O 3} is 10 to 22 wt%, Na ₂ O is 3 to 16 wt%, _{K 2} O is 5 to 16 wt%, CaO 0 to _4% by _weight, B 2 _{O 3} It has a mass composition of 0 to 4% by mass, the glass further has Mg as a constituent element, and the mass composition of MgO in terms of oxide is 13% by mass or more and 30% by mass with the total glass being 100% by mass. In addition to the mass% or less, at least half of the amount is present as a constituent component of crystals precipitated in the glass matrix.
Therefore, the content and composition of other components can be arbitrarily determined in light of various standards.

  The first and second bonding materials disclosed herein include, for example, a bonding material for bonding cells and interconnectors that constitute SOFC to each other, or a cell (or stack) and gas pipe that constitute an SOFC system. Is a bonding material that can be used to bond the two together.

The crystal-containing glasses 1 and 2 constituting the first and second bonding materials will be described. In the following description, the description that does not specify the crystal-containing glass 1 or the crystal-containing glass 2 is an explanation common to these crystal-containing glasses. The same applies to the case where the first or second bonding material is not specified.
The crystal-containing glass disclosed here is used in the SOFC operating temperature range (for example, 700 ° C. to 1200 ° C., preferably 700 ° C. to 1000 ° C., typically 800 ° C. to 1000 ° C.) and more (for example, 1200 ° C. or more). A glass having a composition that hardly melts in a high temperature range is preferred. 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 crystal-containing glass contains Si, Al, Na, and K as its essential constituent elements, and may contain Ca and B as optional (additional) constituent elements.
These constituent elements are converted into oxide forms of the elements (ie, silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), sodium oxide (Na ₂ O), potassium oxide (K ₂ O), and optionally calcium oxide (CaO ), And an oxide glass contained as boron oxide (B ₂ O ₃ )). In addition to these components, various components (typically, various oxide components) can be further included in addition to these components as long as they do not prevent the precipitation of crystals suitable for the practice of the present invention.
Among the crystal components of the crystal-containing glass, for example, for cristobalite crystals and / or leucite crystals, the amount of such crystals deposited is the content (mixing ratio) of the constituent elements (essential constituent elements) in the crystal-containing glass in terms of oxides. ) Can be adjusted as appropriate. The mass composition of the crystal-containing glass on which such crystals can be precipitated is the total of the six constituent elements (that is, SiO ₂ , Al ₂ O ₃ , Na ₂ O, K ₂ O, CaO, and B _{2 in} terms of oxide). O ₃₎ as 100 mass%, SiO ₂ is 60 to 78 wt%, _Al 2 _{O 3} is 10 to 22 wt%, Na ₂ O is 3 to 16 wt%, _{K 2} O is 5 to 16 wt%, CaO Is preferably 0 to 4% by mass, and B ₂ O ₃ is preferably 0 to 4% by mass.

SiO ₂ is a component mainly constituting cristobalite crystal, leucite crystal and forsterite crystal, and is a main component constituting the skeleton of the glass layer (glass matrix) at 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, when the SiO ₂ content is too low, the amount of cristobalite crystals and / or leucite crystals deposited decreases. In addition, water resistance and chemical resistance are reduced. It is preferred SiO ₂ content of from 60 to 75 wt% of the total crystal-containing glass.

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, and the formation of a glass matrix having a uniform thickness may be impaired, and the amount of leucite crystal precipitation decreases. 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 wt% of the total crystal-containing glass.

K ₂ O is a component that constitutes the leucite crystal and is a component that increases the thermal expansion coefficient (thermal expansion coefficient) together with Na ₂ O. When the K ₂ O content is too low, the amount of leucite crystal precipitation decreases. Further, if the K ₂ O content and the Na ₂ O content are too low, the 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 becomes excessively high, which is not preferable. It is preferred K ₂ O content is 5 to 15% by weight of the total glass composition. Further, it is preferable that Na ₂ O content is 3 to 15 wt% of the total crystal-containing glass. It is particularly preferable that the total of K ₂ O and Na ₂ O is 10 to 20% by mass of the entire crystal-containing glass.

  CaO, which is an alkaline earth metal oxide, is an optional additive component that can adjust the thermal expansion coefficient. CaO is a component that can increase the hardness of the glass matrix and improve the wear resistance. The content of CaO in the entire crystal-containing glass is preferably zero (no addition) or 3% by mass or less.

B ₂ O ₃ is also an optional additive component. B ₂ O ₃ is considered to exhibit the same action as Al ₂ O ₃ in glass, and can contribute to the multi-componentization of the glass matrix. Moreover, it is a component which contributes to the improvement of the meltability at the time of bonding material preparation. On the other hand, too much of this component is not preferable because it causes a decrease in acid resistance. The content of B ₂ O _{3 in} the entire crystal-containing glass is preferably zero (no addition) or about 3% by mass or less.
In addition to the oxide components described above, components that are not essential in the practice of the present invention (for example, ZnO, Li ₂ O, Bi ₂ O ₃ , SrO, SnO, SnO ₂ , CuO, Cu ₂ O, TiO ₂ , ZrO) ₂ , La ₂ O ₃ ) can be added according to various purposes.

  Moreover, the crystal-containing glass disclosed here includes Mg as an essential constituent element in addition to the constituent elements in both the crystal-containing glass 1 and the crystal-containing glass 2. In addition, such crystal-containing glass may contain at least half (half amount) of Mg as a constituent component of the crystal component, and it is arbitrary whether Mg is included or not included as a constituent component of the glass matrix. For example, when Mg (typically MgO) is contained as a constituent component of the glass matrix, it becomes a component capable of adjusting the coefficient of thermal expansion together with CaO of the alkaline earth metal oxide. In this case, the coefficient of thermal expansion can be adjusted by adjusting the viscosity at the time of melting the glass.

  Moreover, in the said crystal containing glass, the kind of crystal component which can precipitate in a glass matrix may differ with the content rate (mass composition) of Mg contained in this glass. That is, in such a crystal-containing glass, the mass composition of Mg is the entire crystal-containing glass in terms of oxide (all the above-described constituent elements including Mg, for example, Si, Al, Na, K, Ca, B, and Mg described above). Is a constituent element, and when it is 3% by mass or more and less than 13% by mass when the total amount of these elements in terms of oxide) is 100% by mass, at least forsterite crystals are precipitated in the glass matrix. A crystal-containing glass having a composition to be obtained (crystal-containing glass 1) is obtained. In addition, at least half (half amount) of MgO contained in the crystal-containing glass with the above-described mass composition (content ratio) is included as a constituent component of crystals (mainly forsterite crystals) that can be precipitated in the crystal-containing glass. The remaining Mg can be preferably contained as a glass component of the crystal-containing glass (a constituent component of the glass matrix). More preferably, about 50 mass% to 75 mass% of Mg contained in the crystal-containing glass can contribute as a constituent element (component) of the precipitated crystal. The crystal-containing glass 1 may include, for example, a cristobalite crystal, a leucite crystal, etc. as a crystal other than the forsterite crystal.

  On the other hand, when the mass composition of Mg is 13% by mass or more and 30% by mass or less when the total crystal-containing glass is 100% by mass in terms of oxide, the crystal-containing glass is contained in the glass matrix. A crystal-containing glass (crystal-containing glass 2) having a composition in which a crystal made of MgO and at least one of a cristobalite crystal, a leucite crystal, and a forsterite crystal can precipitate is obtained. Moreover, it is preferable that at least half of the MgO contained in the crystal-containing glass with the mass composition (content) as described above is contained as a constituent component of crystals (mainly MgO crystals) that can be precipitated in the crystal-containing glass. . More preferably, about 75% to 90% by mass of Mg in the crystal-containing glass can contribute as a constituent element (component) of the crystal. Furthermore, within the range of the mass composition (content rate) of Mg, as the content rate increases, the proportion of the MgO crystals in the precipitated crystals can be increased.

  As described above, among the plurality of crystals that can be precipitated in the glass matrix of the crystal-containing glass, the forsterite crystal, or the MgO crystal can be present together with other crystals, whereby the above-mentioned crystal-containing glass is formed. Even if the joint formed using the joining material is exposed to a high temperature of, for example, 1200 ° C. or higher, re-dissolution of each crystal (for example, cristobalite crystal or leucite crystal) precipitated in the glass matrix is prevented, Such a decrease in the thermal expansion coefficient of the joint can be suppressed. Therefore, a crystal-containing glass suitable as a bonding material for SOFC that achieves both high heat resistance and airtightness at a high level can be obtained. Here, as described above, the mass composition of Mg in the crystal-containing glass is 3% by mass or more and less than 13% by mass or 13% by mass or more and 30% by mass or less in terms of oxide. Preferably there is. If the mass composition is less than 3% by mass, there is a possibility that various crystals in the crystal-containing glass may be redissolved in the bonding material made of the crystal-containing glass. Moreover, the thermal expansion coefficient (average value between room temperature (25 ° C.) to 500 ° C. based on a general differential expansion method (TMA)) of the bonding material after being exposed to a temperature of at least 1200 ° C. is greatly increased. There is a risk that the difference between the coefficient of thermal expansion of the part to be joined widens and the joining part is peeled off, cracked, etc., and the mechanical strength of the joined part is lowered. On the other hand, if the mass composition is more than 30% by mass, the content of the crystal component (mainly MgO crystal) in the crystal-containing glass is too large, and the glass component is reduced, and MgO cannot be completely sintered. For this reason, there is a possibility that the denseness of the joint cannot be ensured and a joint having high airtightness cannot be formed.

Preparation of the crystal-containing glass containing the crystal component in the glass component (glass matrix) as described above is preferably performed when the bonding material has a coefficient of thermal expansion to be bonded (for example, SOFC cell and interconnector, or SOFC cell and gas pipe). The above components are mixed so as to approximate the thermal expansion coefficient of As an example, the solid electrolyte of the gas pipe and the cell is formed from a dense body of zirconia oxide such as YSZ, and the SOFC and the gas pipe are joined so as to block between the dense gas pipe and the solid electrolyte. In the case of (sealing), the composition is adjusted so that the thermal expansion coefficient is 9 × 10 ⁻⁶ K ^{−1 to} 13 × 10 ⁻⁶ K ⁻¹ by approximating the thermal expansion coefficient of the zirconia-based oxide. Then, the crystal-containing glass may be prepared.

Here, in a bonding material comprising a glass composition containing cristobalite crystals and / or leucite crystals in the glass matrix having the above composition but not containing forsterite crystals or MgO crystals, a typical operating temperature range of SOFC (800 ° C. Even when exposed to ˜1000 ° C., the crystalline component does not re-dissolve, and the thermal expansion coefficient of the constituent member of SOFC (for example, 9 × 10 ⁻⁶ K ^{−1 to} 13 × 10 ⁻⁶⁾ K ⁻¹ ). However, when exposed to a temperature range above the use temperature range, particularly 1200 ° C or higher (eg, 1200 ° C to 1300 ° C or higher temperature 1300 ° C to 1400 ° C), the crystal component can be dissolved again, Since the thermal expansion coefficient can be significantly reduced (for example, 6 × 10 ⁻⁶ K ^{−1 to} 9 × 10 ⁻⁶ K ⁻¹ ), the joint formed using such a bonding material has a temperature of 1200 ° C. or higher. It was difficult to achieve excellent heat resistance at high temperatures.

In contrast to such a forsterite crystal or MgO crystal-free bonding material, a bonding material composed of the crystal-containing glass disclosed herein (that is, a crystal-containing glass including forsterite crystal or MgO crystal) is 1200 ° C. Even when exposed to the above high temperature range, the crystal component does not re-dissolve including cristobalite crystal and leucite crystal, and the thermal expansion coefficient is the same as when exposed to the temperature range of 800 ° C. to 1000 ° C. Since 9 × 10 ⁻⁶ K ^{−1 to} 13 × 10 ⁻⁶ K ⁻¹ can be held, formation of a joint portion having excellent heat resistance is realized. Therefore, by using the bonding material made of the crystal-containing glass disclosed here, even when exposed to a high temperature range of 1200 ° C. or higher, it provides high airtightness and mechanical strength to the bonded portion, and gas leaks over a long period of time. Production of high performance SOFC (or SOFC system) that can be prevented at a high level can be realized.

Next, the manufacturing method of the bonding material disclosed here will be described.
It is preferable that the manufacturing method of the joining material disclosed here includes the following steps. That is, in this manufacturing method, first, glass raw material powder is prepared, and the raw material powder is melted to prepare glass. Next, after the prepared glass is pulverized, MgO powder is added, and Preparing a mixed powder with MgO and precipitating a crystal component in the glass matrix by crystallizing the mixed powder. Here, in this manufacturing method, as the glass raw material powder, the following composition in terms of oxide-converted mass ratio:
SiO ₂ 60 to 75 wt%;
Al ₂ O ₃ 10-20% by mass;
Na ₂ O 3-15% by mass;
K ₂ O 5-15% by mass;
CaO 0 to 3% by mass;
B ₂ O _{30 to} 3% by mass;
MgO 0 to 3% by mass;
Prepared from substantially the same. Here, in this manufacturing method, the amount of MgO powder added to the prepared glass (glassy intermediate) is an amount corresponding to 3% by mass or more and less than 10% by mass of the entire glass raw material powder. Thus, at least forsterite crystals are precipitated as crystal components in the glass matrix (that is, the above-mentioned crystal-containing glass 1 is prepared). Alternatively, in this manufacturing method, the amount of MgO powder added to the prepared glass (glassy intermediate) is an amount corresponding to 10% by mass or more and 30% by mass or less of the entire glass raw material powder. To precipitate a crystal made of magnesium oxide (MgO) as a crystal component and at least one crystal selected from cristobalite crystal, leucite crystal and forsterite crystal in the glass matrix (that is, the crystal-containing glass 2 described above) Is prepared).

  Furthermore, in this manufacturing method, in the step of adding the MgO powder, the MgO powder is added to the glass powder before the crystallization treatment, and the crystallization treatment is performed on the mixed powder after the addition of the MgO powder. It is preferable. In the bonding material obtained by crystallizing the mixed powder after the addition of MgO to precipitate the crystal component (typically, a plurality of crystal components are simultaneously precipitated), the glass component was previously precipitated by crystallizing the glass. Compared to a bonding material obtained by adding MgO to glass (typically heat treatment after the addition), the effect of suppressing a decrease in thermal expansion coefficient under a high temperature range of 1200 ° C. or higher can be improved. .

Hereinafter, a preferable example of the manufacturing method of the bonding material disclosed herein will be described.
First, a compound for obtaining various oxide components constituting the glass component (glass matrix) of the bonding material (crystal-containing glass) (for example, oxides, carbonates, nitrates, composite oxides and the like containing each component) An industrial product, a reagent, or various mineral raw materials) and other additives as necessary (typically an admixture obtained by mixing them) are prepared as glass raw material powders. Such glass material powder, SiO ₂ is 60 to 75 wt% in mass ratio of oxide equivalent, _Al 2 _{O 3} is 10 to 20 wt%, Na ₂ O 3 to 15 wt%, _{K 2} O 5-15 It is preferably prepared so as to be substantially composed of such a composition that the mass%, CaO is 0 to 3 mass%, B ₂ O ₃ is 0 to 3 mass%, and MgO is 0 to 3 mass%. . The average particle size of the compound (typically powder) for obtaining each of the oxide components is preferably about 1 μm to 10 μm. Each of these compounds and additives is put 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 admixture (glass raw material powder) thus obtained is dried, placed in a refractory crucible, and heated and melted under suitable high temperature (typically 1000 ° C. to 1500 ° C.) conditions. In this way, glass (glassy intermediate) having the above composition is prepared.

Next, the obtained glass (glassy intermediate) is pulverized to an appropriate size (particle size) to produce a glass powder. It is preferable to carry out a classification treatment after the glass pulverization treatment. The particle size (average particle size) of the glass powder is not particularly limited as long as it is a particle size that can be easily and uniformly mixed with MgO powder added later, and is easy to handle, but for example, a range of 0.5 μm to 50 μm is appropriate. And preferably 1 μm to 10 μm.
MgO powder is added to the glass powder (glassy intermediate powder) obtained by this pulverization. The MgO powder added here can also contribute as a constituent component of the glass matrix in the crystal-containing glass 1 or the crystal-containing glass 2 finally obtained, but is a crystal mainly containing Mg that can be precipitated in the glass matrix as a constituent element. It can contribute to the formation of (mainly forsterite crystals and / or MgO crystals). Regarding the average particle diameter of the MgO powder, it is easy to form a mixed powder uniformly mixed with the glassy intermediate powder, and in the subsequent crystallization treatment, the Mg-containing crystal is combined with the cristobalite crystal and / or the leucite crystal. A size capable of being preferably deposited is preferred. Such an average particle size is preferably 0.1 μm to 10 μm, more preferably 0.5 μm to 5 μm.
As addition amount of MgO powder, it is preferable to add in the ratio of 3 mass% or more and 30 mass% or less with respect to the mass of the said whole glass raw material powder in conversion of an oxide. Here, when such addition amount is 3% by mass or more and less than 10% by mass, at least forsterite crystals can be precipitated as crystal components in the finally obtained crystal-containing glass (crystal-containing glass 1) (others) Crystal such as cristobalite crystal or leucite crystal may also be precipitated). Moreover, when the addition amount of the MgO powder is 10% by mass to 30% by mass of the whole glass raw material powder, the crystal-containing glass (crystal-containing glass 2) to be obtained contains MgO crystals as crystal components and the crystals. In addition, at least one of a cristobalite crystal, a leucite crystal, and a forsterite crystal may be precipitated.

Next, the added MgO powder and the glass powder (glassy intermediate powder) are mixed for several hours to several tens of hours using a mixer such as a dry or wet ball mill in the same manner as described above. In this way, a mixed powder in which MgO and glass are uniformly mixed is obtained. The average particle size of the mixed powder is preferably 0.5 μm to 10 μm, more preferably 1 μm to 5 μm.
Next, a crystallization process is performed on the mixed powder obtained as described above. In this crystallization treatment, the mixed powder is subjected to a temperature range in which crystallization can be induced, for example, a temperature range of 1000 ° C. or lower and a relatively high temperature range (for example, 600 ° C. to 1000 ° C., more preferably 800 ° C. to 1000 ° C. C.) for a predetermined time (typically 30 minutes or more, for example, 30 minutes to 60 minutes). As a preferred example, the mixed powder is heated from room temperature to about 100 ° C. at a temperature rising rate of about 1 to 5 ° C./min, from about 100 ° C. at a temperature rising rate of 1 to 10 ° C./min, After holding for about 30 minutes to 60 minutes in a temperature range of 800 ° C. to 1000 ° C., the above-mentioned various crystals can be simultaneously precipitated in the glass matrix by cooling to room temperature at a temperature drop rate of 1 to 5 ° C./min. it can. In this way, the crystal-containing glass 1 or 2 can be obtained.
The crystal-containing glass thus obtained can be formed into a desired form by various methods. For example, by pulverizing with a ball mill or appropriately sieving (classifying), a powdery crystal-containing glass (glass composition) having a desired average particle size (for example, 0.1 μm to 10 μm) can be obtained.
Further, an appropriate amount of water is added to the obtained powdery crystal-containing glass and mixed using a ball mill similar to the above. Then, the powdery bonding material 1 or 2 according to the present invention can be obtained by performing a drying process for a predetermined time.

The powdery bonding material obtained as described above is typically prepared in the form of a paste (slurry) like the conventional bonding material, and is applied to the connection portion (bonded portion) to be bonded. can do. For example, a paste can be prepared by mixing an appropriate binder or solvent with the obtained bonding material. In addition, the binder, solvent, and other components (for example, dispersant) used in the paste are not particularly limited, and can be appropriately selected from conventionally known ones in paste production.
For example, a suitable example of the binder includes 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 SOFC (for example, solid electrolyte and / or fuel electrode) to be joined and the joined part of the gas pipe (or interconnector) are contacted and connected to each other, and the connected part is prepared as a paste. Apply the bonding material. Then, the coated material is dried at an appropriate temperature (typically 60 ° C. to 100 ° C., for example, 80 ° C. ± 10 ° C.). Next, a temperature range that is preferably equal to or higher than the operating temperature range of SOFC (for example, 700 ° C. to 1000 ° C. or higher temperature range, for example, 800 ° C. to 1200 ° C.), and the glass does not flow out. (For example, when the use temperature range is 700 ° C. to 1000 ° C., typically, it is 800 ° C. to 1200 ° C., and when the use temperature range is approximately 1200 ° C., it is typically fired at 1200 ° C. to 1300 ° C.). As a result, a joint portion (seal portion) that shuts off gas flow (that is, has no gas leak) is formed at the connection (connection) portion between the SOFC and the gas pipe (or interconnector). For example, the SOFC and the gas pipe are joined by applying the joining material so that a gap that may be generated between the dense solid electrolyte and the gas pipe in the SOFC is closed. In the joint formed in this way, gas (for example, fuel gas) flowing through the gas pipe is supplied to the SOFC without leaking. Further, such a bonding material exhibits flexibility in the operating temperature range of the SOFC, so that, for example, even when stress can be generated in the bonded portion due to reduction expansion associated with the contact with the fuel gas, the air tightness and durability of the bonded portion. Sex can be kept high.

The SOFC to which the above-described bonding materials (first bonding material and second bonding material) can be preferably applied will be described.
Such a bonding material may be an SOFC having various structures (for example, a conventionally known flat plate type, cylindrical type, or a flat tubular type in which the peripheral side surface of the cylinder is vertically crushed). It can be preferably applied to the present invention and is not particularly limited to the shape or size of the SOFC.

Further, as a solid electrolyte included in the SOFC to which the bonding material disclosed herein can be applied, a dense electrolyte having high oxygen ion conductivity and no gas permeability in both an oxidizing (air) atmosphere and a reducing (fuel gas) atmosphere. In particular, a solid electrolyte made of a zirconia-based oxide is preferable. As such a zirconia-based oxide, zirconia (YSZ) stabilized with yttria (Y ₂ O ₃ ) is typically used. Other examples include zirconia (CSZ) stabilized with calcia (CaO) and zirconia (SSZ) stabilized with scandia (Sc ₂ O ₃ ).
Further, the fuel electrode and the air electrode provided in the SOFC 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. It is preferable to use a porous body made of these materials as a fuel electrode and an air electrode, respectively.

Moreover, it does not specifically limit as a member joined with SOFC provided with the above electrodes and solid electrolytes. SOFC (typically SOFC as a stack with a plurality of single cells), or SOFC to construct and use an SOFC system in which various system components (for example, gas pipes) are attached to the SOFC. If it is a member which needs to be connected, it will not restrict | limit especially as a joining object, It can join with the said SOFC with the said joining material. Even when the coefficients of thermal expansion of the joined parts have a relatively large difference (for example, about 1 × 10 ⁻⁶ K ⁻¹ ), the heat of the entire SOFC (or SOFC system) structure If the expansion coefficient is approximately the same as that of the bonding material, the bonded portions can be bonded to each other using the bonding material.

  As an example of a member that can be an SOFC joining target, an interconnector that can be disposed between the single cells in order to construct a stack by electrically connecting the single cells of the SOFC can be preferably exemplified. As a configuration of the SOFC including a joint portion in which an interconnector and a single cell are joined by the joining material, for example, a flat plate-type SOFC 10 as schematically shown in FIG. That is, as shown in FIG. 1, in the SOFC 10, the air electrode 14 is formed on one surface of the plate-shaped solid electrolyte 12, and the fuel electrode 16 is formed on the other surface. Material) interconnectors 18A and 18B joined via 20 are 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) flow path 4 is formed. These gas flow paths 2 and 4 may be pipes (tubular or tubular members) formed of the same material as the interconnector, for example, instead of the groove-shaped one as shown in FIG. Each gas to be flowed may flow in the pipe.

As the above-described interconnector, a lanthanum chromite-based perovskite oxide (lanthanum chromite-based oxide) that physically cuts off oxygen supply gas (for example, air) and fuel gas and has electronic conductivity is preferably used. Can be. Such a lanthanum chromite oxide is represented by a general formula: La _(1-x) Ma _(x) Cr _(1-y) Mb _(y) O ₃ , and Ma and Mb in the formula are the same or different from each other. 1 or 2 or more types of alkaline earth metals, 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 . In the above general formula, the number of oxygen atoms is shown to be 3, but in actuality, the number of oxygen atoms in the composition ratio may be 3 or less (typically less than 3).
Further, when a high thermal expansion material is used for the interconnector, as such a suitable material, for example, a lanthanum chromite oxide (La _0.7 Sr _0.3 CrO ₃ ) in which a part of La is substituted with Sr. Etc.

  In the SOFC 10 having the above-described configuration, the bonding material 20 is applied so that a gap that may be generated between the dense solid electrolyte 12 and the interconnectors 18A and 18B is blocked by the bonding material 20. Interconnector 18A, 18B and SOFC10 (solid electrolyte 12) can be joined and connected. The joint 20 formed by such joining has high hermeticity and mechanical strength even when exposed to a high temperature range of, for example, 1200 ° C. or higher, and can have complete insulation. Therefore, the SOFC 10 can realize a high-performance SOFC excellent in heat resistance and battery characteristics by preventing gas leakage.

In addition, since the bonding material disclosed herein can be preferably bonded even to a bonding target that is difficult to be bonded by pressure sealing or diffusion bonding due to insufficient strength or the like, for example, the fuel electrode is used as a support base material on the fuel electrode. The present invention can also be suitably applied to an anode-supported SOFC having a configuration including a solid electrolyte formed in a thin film shape (for example, a film thickness of 100 μm or less). An example of the structure of such an anode-supported SOFC is SOFC 30 schematically shown in FIG. As shown in FIG. 2, the SOFC 30 includes a porous fuel electrode 36, a dense solid electrolyte membrane 32 laminated on one surface of the fuel electrode 36, and a porous membrane laminated on the solid electrolyte membrane 32. A high-quality air electrode 34 is provided. Further, the SOFC 30 is disposed on the fuel electrode 36 side and an air supply gas pipe 54 for supplying air disposed on the air electrode 34 side in order to supply air and fuel gas to the SOFC 30, respectively. The SOFC system 100 including the SOFC 30 and the gas pipes 54 and 56 may be constructed by joining the fuel gas supply gas pipe 56 for supplying the fuel gas. In the system 100, the SOFC 30 and the gas pipes 54 and 56 are preferably joined by the joining material 40 to form a joint (40).
By applying the bonding material 40, a gap that may be generated between the dense solid electrolyte membrane 32 and the gas pipes 54 and 56 is closed by the bonding material 40, and the porous fuel electrode 36 is completely covered. In this state, the gas pipes 54 and 56 and the SOFC 30 can be joined and connected. Since the joint 40 formed by such joining has high hermeticity and mechanical strength even if it is exposed to a high temperature range of, for example, 1200 ° C. or higher, the SOFC system 100 is preferably resistant to gas leaks. A high-performance SOFC system with excellent performance and battery characteristics can be realized.
The material of the gas pipes 54 and 56 is not particularly limited. For example, when the gas pipes 54 and 56 are formed of a dense body of zirconia-based oxide such as YSZ which is the same material as the solid electrolyte 32, the bonding material 40 is used to form a solid. It is easy to join with the electrolyte 32 and can be suitably used. The shape and size of the gas pipe can be appropriately set in accordance with the size of the SOFC 30 to be connected and the size of the joint portion.

  The SOFC 10 having the interconnector as described above or the anode-supported SOFC 30 as a suitable example may be manufactured in accordance with the conventional manufacturing of this type of SOFC, and specially constructed for constructing the SOFC of the present invention. Does not require any special processing. A solid electrolyte, a fuel electrode and an air electrode can be formed by various methods conventionally used. Although not intended to be particularly limited, when an anode-supported SOFC is constructed, for example, the following is performed. First, a fuel electrode that can function as a support base (support) is manufactured. First, a slurry-like molding material for a fuel electrode made of a predetermined cermet material (for example, a YSZ powder having an average particle diameter of about 0.1 μm to 10 μm, a NiO powder having an average particle diameter of about 1 μm to 10 μm, a binder, a dispersant, a solvent) Prepare. Next, using this molding material, a fuel electrode molded body is produced by, for example, extrusion molding. The shape of the fuel electrode molded body is not particularly limited as long as the fuel gas can permeate in the direction of the solid electrolyte 32 without stagnation. The sheet shape (or flat plate shape) shown in FIG. It is preferably a hollow box shape having a hollow portion (gas flow path) for allowing the fuel gas to flow into the fuel electrode, or a hollow flat shape (flat tubular shape).

  Next, a solid electrolyte membrane is produced. That is, a predetermined material (for example, a YSZ powder having an average particle size of about 0.1 μm to 10 μm, a binder, a dispersant, and a solvent) is mixed to prepare a molding material for a slurry (paste) solid electrolyte. The solid electrolyte molding material is printed and molded on the fuel electrode molded body at a film thickness of 100 μm or less (typically 1 μm to 100 μm, preferably 10 μm to 100 μm, for example 10 μm to 50 μm). An electrolyte membrane is formed. The solid electrolyte membrane supported by the fuel electrode molded body is dried and then fired in the air at a firing temperature of 1200 ° C. to 1400 ° C. As a result, a fired body in which a dense solid electrolyte membrane is formed on the porous fuel electrode is obtained.

Next, an air electrode is produced. That is, a slurry-like molding material for an air electrode comprising a predetermined material (for example, LaSrO ₃ powder having an average particle diameter of about 1 μm to 10 μm, a binder, a dispersant, and a solvent is prepared. An unfired air electrode layer (film) is formed by printing on the surface of the solid electrolyte membrane after firing at a thickness of 100 μm or less (typically 1 μm to 100 μm, preferably 10 μm to 100 μm, for example, 10 μm to 50 μm). This is dried and then fired in the air at a firing temperature of 1000 ° C. to 1200 ° C. In this way, a porous air electrode is formed on the solid electrolyte membrane, and the fuel electrode, the solid electrolyte membrane, and An anode-supported SOFC (single cell) having a laminated structure composed of air electrodes is manufactured.

The method for manufacturing the gas pipe may be the same as the method for manufacturing a conventional gas pipe for supplying gas to the SOFC, and is not particularly limited. For example, a slurry-like molding material for a gas pipe made of a predetermined material (for example, a YSZ powder having an average particle diameter of about 0.1 μm to 10 μm, a binder, a dispersant, and a solvent) is prepared. Then, using this molding material, it is molded into a tube of a predetermined size by, for example, extrusion molding. The obtained molded body can be fired in an appropriate temperature range (for example, 1200 ° C. to 1600 ° C.) in the atmosphere to produce a tubular gas tube. Further, a commercially available gas pipe for SOFC may be used.
The SOFC system can be constructed by preferably joining the gas pipes fired and completed as described above and the SOFC using the joining material. In addition, you may perform simultaneously baking of a gas pipe (unfired molded object), and formation of the junction part by a paste-form joining material.

  As described above, the preferred examples of the SOFC and the SOFC system including the joint portion formed by using the joining material according to the present invention have been described with reference to FIGS. 1 and 2, but the present invention is not limited thereto. For example, an SOFC system comprising a gas pipe for supplying gas to an SOFC (stack) 10 having interconnectors 18A and 18B as shown in FIG. 1, wherein the SOFC 10 and the gas pipe are disclosed herein. An SOFC system provided with a joined portion joined using a joining material. Further, the SOFC system including the anode-supported SOFC is not limited to the structure in which the gas pipe is connected to the SOFC 30 as shown in FIG. 2. For example, the fuel electrode has a hollow box shape (or a flat corner). SOFC system having an SOFC having a cylindrical shape), and a fuel gas supply gas pipe is connected (joined) to the fuel electrode so that fuel gas is supplied to the hollow portion of the fuel electrode. Even in the system, the fuel electrode and the gas pipe can be preferably bonded using the bonding material. Further, the bonding material can be preferably applied to an SOFC stack configured by bonding a plurality of single cells (for example, anode-supported SOFC cells) to each other without using an interconnector.

  Hereinafter, examples related to the present invention will be described with reference to FIG. 2, but the present invention is not intended to be limited to those shown in the following examples.

<Production of anode supported SOFC (single cell)>
3-8 mol% yttria stabilized zirconia (YSZ) powder (average particle size: about 1 μm) and nickel oxide (NiO) powder common binder (here, polyvinyl alcohol (PVA) was used), and solvent (here. Then, water was added and kneaded. Next, the kneaded product (slurry or paste-like fuel electrode molding material) was subjected to sheet molding to obtain a disk-shaped fuel electrode molded body having a diameter of about 20 mm and a thickness of about 1 mm.
Next, the same binder, dispersant and solvent as above were added to 3-8 mol% YSZ powder (average particle size: about 1 μm) and kneaded. Next, this kneaded product (a paste-form molding material for a solid electrolyte membrane) was printed and formed on the fuel electrode molded body into a disk shape having a diameter of 16 mm and a thickness of 10 μm to 30 μm. The unfired laminate comprising the fuel electrode compact and the solid electrolyte membrane supported on the compact was dried and then fired in the air at a firing temperature of 1200 ° C to 1400 ° C.
Next, a general binder (here, ethyl cellulose was used) and a solvent (here, terpineol was used) were added to and kneaded with LaSrO ₃ powder (average particle size: about 1 μm). Next, this kneaded product (a paste-like molding material for an air electrode) was printed and formed on the solid electrolyte membrane into a disk shape having a diameter of 13 mm and a thickness of 10 μm to 30 μm. Subsequently, it baked in air | atmosphere at the calcination temperature of 1000 to 1200 degreeC. In this manner, an anode supported SOFC 30 including the fuel electrode 36, the solid electrolyte membrane 32, and the air electrode 34 as shown in FIG.

<Production of gas pipe>
The same binder, dispersant, and solvent as above were added to 3-8 mol% YSZ powder (average particle size: about 1 μm) and kneaded to prepare a slurry or paste-like molding material for a gas pipe. Next, the molding material was molded into a tubular shape by extrusion molding or the like. The obtained molded body was fired at 1300 ° C. to 1600 ° C. in the atmosphere to produce two tubular gas pipes 54 and 56 (see FIG. 2).

<Preparation of paste-like bonding material by process A>
Here, according to the procedure of the process A shown below, paste-like bonding materials (samples 1 to 8) having different MgO addition amounts were produced.
First, SiO ₂ powder, Al ₂ O ₃ powder, Na ₂ CO ₃ powder, K ₂ CO ₃ powder, MgCO ₃ powder, CaCO ₃ powder and B ₂ O ₃ powder having an average particle diameter of about 1 μm to 10 μm, respectively, The following compounding ratio, that is, in terms of oxide, SiO ₂ is 67.0% by mass, Al ₂ O ₃ is 13.9% by mass, Na ₂ O is 8.5% by mass, K ₂ O is 9.1% by mass, Mixing was performed at such a mixing ratio that CaO was 0.8% by mass, B ₂ O ₃ was 0.1% by mass, and MgO was 0.6% by mass to obtain glass raw material powder.
Next, this glass raw material powder was melted in a temperature range of 1000 ° C. to 1500 ° C. (here, 1450 ° C.) to form glass (glassy intermediate).
The obtained glass was pulverized to an average particle diameter of about 2 μm to produce a glass (glassy intermediate) powder.
MgO powder (average particle size: about 1 μm) is prepared, and the addition amount is changed within the range of 0% by mass to 40% by mass with respect to the total mass of the glass raw material powder (total mass in terms of oxide), and MgO The powder was added to the glass (glassy intermediate) powder in each addition amount and mixed well. At this time, the average particle size of the mixed powder was about 1.5 μm. In this way, eight types of mixed powders having different compositions with different amounts of MgO powder were prepared.
The following treatment was performed as a crystallization treatment on the above eight kinds of mixed powders. First, the mixed powder is heated from room temperature to about 100 ° C. at a rate of about 1 to 5 ° C./min, and from about 100 ° C. at a rate of temperature increase of 1 to 10 ° C./min. After maintaining at a temperature range of 1000 ° C. (here, 850 ° C. ± 50 ° C.) for about 30 minutes to 60 minutes, it was cooled to room temperature at a temperature decrease rate of 1 to 5 ° C./min. In this way, a total of 8 types of crystal-containing glasses (samples 1 to 8) having different compositions were prepared. Table 1 shows the correlation between each sample 1 to 8 and the amount of MgO powder added to the glass powder.
Thereby, in Sample 1, cristobalite crystals and / or leucite crystals were mainly precipitated. In samples 2 to 4, forsterite crystals were precipitated so as to be dispersed in the glass matrix. As other crystals, cristobalite crystals and / or leucite crystals were precipitated. In Sample 5, MgO crystals were also observed along with the above crystals. In Samples 6 to 8, MgO crystals were precipitated so as to be dispersed in the glass matrix, and at least one of cristobalite crystals, leucite crystals, and forsterite crystals was precipitated. Moreover, it was recognized that the precipitation amount of the MgO crystal increases in the order of Sample 6, Sample 7, and Sample 8.
Next, the obtained crystal-containing glass (samples 1 to 8) was pulverized and classified to obtain a powdery crystal-containing glass (that is, a bonding material) having an average particle diameter of about 2 μm.

<Preparation of paste-like bonding material by process B>
Here, according to the procedure of the process B shown below, the paste-like joining materials (samples 11-18) from which the addition amount of MgO differs were produced.
First, SiO ₂ powder, Al ₂ O ₃ powder, Na ₂ CO ₃ powder, K ₂ CO ₃ powder, MgCO ₃ powder, CaCO ₃ powder and B ₂ O ₃ powder having an average particle diameter of about 1 μm to 10 μm, respectively, The following compounding ratio, that is, in terms of oxide, SiO ₂ is 67.0% by mass, Al ₂ O ₃ is 13.9% by mass, Na ₂ O is 8.5% by mass, K ₂ O is 9.1% by mass, Mixing was performed at such a mixing ratio that CaO was 0.8% by mass, B ₂ O ₃ was 0.1% by mass, and MgO was 0.6% by mass to obtain glass raw material powder.
Next, this glass raw material powder was melted in a temperature range of 1000 ° C. to 1500 ° C. (here, 1450 ° C.) to form glass (glassy intermediate).
The obtained glass was pulverized to an average particle diameter of about 2 μm to produce a glass (glassy intermediate) powder.
Next, the following treatment was performed as a crystallization treatment. First, the glass powder is heated from room temperature to about 100 ° C. at a rate of about 1 to 5 ° C./min, and from about 100 ° C. at a rate of 1 to 10 ° C./min. After maintaining at a temperature range of 1000 ° C. (here, 850 ° C. ± 50 ° C.) for about 30 minutes to 60 minutes, it was cooled to room temperature at a temperature decrease rate of 1 to 5 ° C./min. The glass composition obtained by the crystallization treatment was pulverized.
Next, an MgO powder (average particle size: about 1 μm) is prepared, and the MgO powder is crystallized at an addition amount in the range of 0% by mass to 40% by mass with respect to the total mass of the glass raw material powder. It added to the powder of the later glass composition, and mixed well. At this time, the average particle size of the mixed powder was about 1.5 μm. In this way, eight types of mixed powders having different compositions with different amounts of MgO powder were prepared.
The eight types of mixed powders were heat-treated at 800 ° C. to 1000 ° C. for 30 minutes to 60 minutes. As a result, eight types of crystal-containing glasses with different MgO addition amounts were obtained. Such eight types of crystal-containing glasses were designated as Samples 11-18. Table 1 shows the correlation between each sample 11 to 18 and the amount of MgO powder added to the glass composition powder after the crystallization treatment.
Next, the obtained crystal-containing glass (samples 11 to 18) was pulverized and classified to obtain a powdery crystal-containing glass (that is, a bonding material) having an average particle size of about 2 μm.

  For samples 1 to 8 and samples 11 to 18 having different processes as described above, 40 parts by mass of each sample, 3 parts by mass of a general binder (here, ethyl cellulose was used), and a solvent (here, terpineol were added) 47 parts by mass were mixed to prepare a total of 16 types of paste-like bonding materials corresponding to Samples 1 to 8 and Samples 11 to 18 in Table 1.

<Joint treatment>
The 16 types of pastes (Samples 1 to 8 and Samples 11 to 18) were each used as a bonding material to perform a bonding process. Specifically, as shown in FIG. 2, gas pipes 54 and 56 are arranged on both sides of the anode-supported SOFC 30, and the solid electrolyte membrane 32 and the gas pipe 54 in the SOFC 30 sandwiched between the gas pipes 54 and 56. , 56 was applied with bonding materials (samples 1 to 8 and samples 11 to 18) so as to close the gaps between them. After drying this at 80 degreeC, it hold | maintained (baking) for 1 hour in the temperature range of 800 to 1000 degreeC in air | atmosphere. As a result, the gas pipes 54 and 56 and the SOFC 30 were joined to form the joint 40. Thus, a specimen (100) of the SOFC system in which the gas pipes 54 and 56 and the SOFC 30 were joined was constructed using a total of 16 types (samples 1 to 8 and samples 11 to 18).

<Gas leak test>
Next, a leak test for confirming the presence or absence of a gas leak from the joint 40 is performed on the specimen (100) of the SOFC system in which the gas pipes 54 and 56 and the SOFC 30 are joined using a total of 16 kinds of samples constructed as described above. went. Specifically, first, with respect to a sample of the SOFC system provided with the sample 1, the sample is heated to 1200 ° C., and hydrogen is supplied from the fuel gas supply gas pipe 56 side toward the fuel electrode 36 under such temperature conditions. The fuel electrode 36 was reduced by supplying the containing gas (a mixed gas of 3% by volume of hydrogen (H ₂ ) gas and 97% by volume of nitrogen (N ₂ ) gas) for 1 hour. Next, while maintaining the temperature at 1200 ° C., air is supplied from the air supply gas pipe 54 side to the sample at a flow rate of 100 mL / min under a pressure of 0.2 Pa, and a fuel gas supply gas pipe Helium (He) gas as a fuel gas was supplied from the 56th side to the specimen for 2 hours at a flow rate of 100 mL / min under a pressure of 0.2 Pa. Gas chromatography to measure the composition of the He gas from the fuel electrode 36 side (i.e. gas pipe 56 side) from the amount of N ₂ gas contained in the He gas, N ₂ in the air from the joint 40 leaks Evaluated whether or not. The leak test was similarly performed for samples 2 to 8 and samples 11 to 18.
The evaluation results of gas leak are shown in Table 1. In Table 1, those having a leak rate of N ₂ gas (volume content of N ₂ gas contained in He exhaust gas) of 1% or less are indicated as “none” and have practical airtightness It was. As shown in Table 1, in Sample 1 and Sample 11 in which MgO added to the glass obtained from the glass raw material powder was not added, the joint 40 was cracked and gas leakage was observed. Therefore, it has been confirmed that the above-mentioned bonding material containing no MgO is unsuitable for use in a high temperature region such as 1200 ° C. In Samples 2 and 12 in which the amount of MgO added was 1% by mass, cracks occurred and gas leaks were observed. Further, in both sample 8 and sample 18, gas leak was recognized as a result of insufficient density of the joint 40 due to excessive addition of MgO. In the samples other than Samples 1, 2, 8, 11, 12, and 18, gas leakage at the joint 40 was preferably prevented, and it was found that the samples had excellent hermeticity and mechanical strength even at the high temperature.

<Evaluation of thermal expansion coefficient after high temperature treatment>
Next, regarding the specimen (100) of the SOFC system in which the gas pipes 54 and 56 and the SOFC 30 are joined using the 16 types of samples (samples 1 to 8 and 11 to 18) constructed as described above, After supplying fuel gas and air for 2 hours under temperature, the coefficient of thermal expansion (however, differential expansion) of each joint 40 obtained by using the paste-like joining materials of Samples 1-8 and 11-18 above The average value between room temperature (25 ° C.) and 500 ° C. based on the method (TMA) was measured. The results are shown in Table 1.
As shown in Table 1, Samples 1 and 11 had a coefficient of thermal expansion of less than 8 × 10 ⁻⁶ K ⁻¹ . Moreover, about the samples 2-8 produced by the process A, only the sample 2 exceeded 13 * 10 <^-6> K < ^{-1 >} . In other samples 3 to 8, all are within the range of 9 × 10 ⁻⁶ K ^{−1 to} 13 × 10 ⁻⁶ K ⁻¹ (strictly, 10.5 × 10 ⁻⁶ K ^{−1 to} 13 × 10 ^−6). K ⁻¹ ). On the other hand, about the samples 12-18 produced by the process B, the sample 12 exceeded 13 * 10 <^-6> K < ^{-1 >} . Also, the samples 13 to 18, all of which were within the range of ^{10 × 10 -6 K -1 ~12.5 ×} 10 -6 K -1. The thermal expansion coefficient of the YSZ solid electrolyte membrane 32 and the YSZ gas pipes 54 and 56 used here under the same conditions was 10.2 × 10 ⁻⁶ K ⁻¹ .
From the above results, comparing the samples (bonding materials) produced in Process A and B, the sample produced in Process A shows a higher thermal expansion coefficient even with the same MgO addition amount. As a result, the process of adding the MgO powder and then performing the crystallization treatment of the glass to simultaneously precipitate the crystal component is lower in the thermal expansion coefficient of the bonding material than the process of adding the MgO powder after the crystallization treatment. It has been found that a suppressive force can be applied. Therefore, in the SOFC or SOFC system, when joining (sealing) a portion having a relatively small change in thermal expansion coefficient even at a high temperature such as 1200 ° C., the joining material produced by the process A is used. It was confirmed that this was preferable.
Moreover, the electrical conductivity in each of the samples 1-8 and 11-18 was measured. That is, after applying a platinum paste serving as an electrode at a predetermined position of each sample, a platinum wire for connecting the current terminal and the voltage terminal to the electrode part is attached and baked at 850 ° C. to 1100 ° C. for 10 to 60 minutes, In a device that can be adjusted to an arbitrary temperature, the electrical conductivity (conductivity) at 1200 ° C. was measured using a DC four-terminal method. As a result, in all the above samples, the conductivity was an undetectable level of 10 ⁻⁷ S / cm or less. Thereby, the insulation of the sample was confirmed.

Moreover, in the preparation method of the said sample 5, it replaces with the MgO powder added to the glass powder comprised from the glass raw material powder, and is the same as the sample 5 except adding 3-8 mol% YSZ powder (average particle diameter: about 1 μm). Thus, Sample 19 was produced. The thermal expansion coefficient of Sample 19 was measured in the same manner as Sample 5, and was 11.1 × 10 ⁻⁶ K ⁻¹ . This was almost the same thermal expansion coefficient as that of Sample 5.
Moreover, when the electrical conductivity of this sample 19 was measured by the direct current four-terminal method (while adjusting the oxygen partial pressure in the apparatus) in the same manner as the sample 5, the ion conductivity of about 10 ⁻⁴ S / cm ( Oxygen ion conductivity) was observed, and a difference of 1000 times or more in electrical conductivity was observed compared to Sample 5.

  As described above, according to this example, the bonding material made of crystal-containing glass that can contain at least one of cristobalite crystal, leucite crystal, and forsterite crystal in the glass matrix, or MgO crystal in addition to the above crystal By joining and connecting the SOFC and the gas pipe so as to block between the zirconia-based solid electrolyte membrane and the gas pipe of the homogeneous material, using a bonding material made of crystal-containing glass containing at least, Even when exposed to a high temperature condition of 1200 ° C., it was possible to join with insulation (that is, form a joint) while ensuring sufficient airtightness and mechanical strength without causing gas leakage. For this reason, a suitable SOFC (single cell, stack) and SOFC system excellent in heat resistance can be provided.

10 Solid oxide fuel cell (SOFC)
12 Solid Electrolyte 14 Air Electrode 16 Fuel Electrode 18A, 18B Interconnector 20 Joint (Joint)
30 Solid oxide fuel cell (SOFC)
32 Solid Electrolyte Membrane 34 Air Electrode 36 Fuel Electrode 40 Joint (Joint)
54 Gas Pipe for Air Supply 56 Gas Pipe for Fuel Gas Supply 100 Solid Oxide Fuel Cell System (SOFC System)

Claims (8)

A joining material for a solid oxide fuel cell mainly composed of glass,
The glass is a glass in which at least forsterite crystals are precipitated in a glass matrix,
The glass is composed of the following six constituent elements, and the following mass composition:
SiO ₂ 60 to 78 wt%;
Al ₂ O ₃ 10~22% by weight;
Na ₂ O 3-16% by mass;
K ₂ O 5-16% by mass;
CaO 0 to 4% by mass;
B ₂ O _{30 to} 4% by mass;
And have
Here, the glass further contains Mg as a constituent element, and the mass composition of MgO is 3% by mass or more and less than 13% by mass with respect to 100% by mass of the whole glass in terms of oxide, and at least of these Half of the amount is present as a constituent of crystals precipitated in the glass matrix ,
A solid oxide fuel cell prepared so as to maintain a coefficient of thermal expansion of 9 × 10 ⁻⁶ K ^{−1 to} 13 × 10 ⁻⁶ K ⁻¹ even after being exposed to a temperature of at least 1200 ° C. Bonding material. A joining material for a solid oxide fuel cell mainly composed of glass,
The glass is a glass in which a crystal composed of magnesium oxide (MgO) and at least one crystal selected from cristobalite crystal, leucite crystal and forsterite crystal are precipitated in a glass matrix,
The glass is composed of the following six constituent elements, and the following mass composition:
SiO ₂ 60 to 78 wt%;
Al ₂ O ₃ 10~22% by weight;
Na ₂ O 3-16% by mass;
K ₂ O 5-16% by mass;
CaO 0 to 4% by mass;
B ₂ O _{30 to} 4% by mass;
And have
Here, the glass further contains Mg as a constituent element, and the mass composition of MgO is 13% by mass or more and 30% by mass or less with respect to 100% by mass of the whole glass in terms of oxide, and at least of these Half of the amount is present as a constituent of crystals precipitated in the glass matrix ,
A solid oxide fuel cell prepared so as to maintain a coefficient of thermal expansion of 9 × 10 ⁻⁶ K ^{−1 to} 13 × 10 ⁻⁶ K ⁻¹ even after being exposed to a temperature of at least 1200 ° C. Bonding material. A plurality of cells including a fuel electrode, an air electrode, and a solid electrolyte;
A solid oxide fuel cell comprising an interconnector disposed and joined between the cells to electrically connect the plurality of cells,
A solid oxide fuel cell, wherein a joint between the cell and the interconnector is formed by the joining material according to claim 1 or 2 . A solid oxide fuel cell comprising one or more cells each including a fuel electrode, an air electrode, and a solid electrolyte;
A gas pipe joined to the solid oxide fuel cell to supply gas to the solid oxide fuel cell;
A solid oxide fuel cell system comprising:
The solid oxide junction between fuel cell and the gas pipe is formed by bonding material according to claim 1 or 2, a solid oxide fuel cell system. A method for producing a solid oxide fuel cell bonding material comprising:
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 3-15% by mass;
K ₂ O 5-15% by mass;
CaO 0 to 3% by mass;
B ₂ O _{30 to} 3% by mass;
MgO 0 to 3% by mass;
Preparing a glass raw material powder prepared so as to be substantially composed of, and melting the raw material powder to prepare a glass;
After pulverizing the prepared glass, adding MgO powder in an amount corresponding to 3% by weight or more and less than 10% by weight of the whole glass raw material powder to prepare a mixed powder of the glass and the MgO; and
Wherein by mixing powders to crystallization treatment, said by precipitating at least a forsterite crystal as a crystal component in the matrix glass, the thermal expansion coefficient after exposure to a temperature of at least 1200 ° C. is 9 × 10 ^- It is prepared to maintain a ^{6 K -1 ~13 × 10 -6 K} -1;
Manufacturing method. A method for producing a solid oxide fuel cell bonding material comprising:
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 3-15% by mass;
K ₂ O 5-15% by mass;
CaO 0 to 3% by mass;
B ₂ O _{30 to} 3% by mass;
MgO 0 to 3% by mass;
Preparing a glass raw material powder prepared so as to be substantially composed of, and melting the raw material powder to prepare a glass;
Crushing the prepared glass, and adding MgO powder in an amount corresponding to 10% by mass or more and 30% by mass or less of the whole glass raw material powder to prepare a mixed powder of the glass and the MgO; and
By crystallizing the mixed powder, a crystal made of magnesium oxide (MgO) as a crystal component in the glass matrix and at least one crystal selected from cristobalite crystal, leucite crystal and forsterite crystal are obtained. Preparing by precipitation to maintain a coefficient of thermal expansion of 9 × 10 ⁻⁶ K ^{−1 to} 13 × 10 ⁻⁶ K ⁻¹ after exposure to a temperature of at least 1200 ° C . ;
Manufacturing method. The manufacturing method of Claim 5 or 6 which heats the said mixed powder for the predetermined time in the temperature range which can induce crystallization of 1000 degrees C or less as said crystallization process. Solid oxide fuel cell bonding material produced by the production method according to any one of claims 5-7.

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