JP5481340B2 - Joining material for solid oxide fuel cell system and use thereof - Google Patents

Description

  The present invention relates to a bonding material for use in a power generation system (that is, a solid oxide fuel cell system) mainly composed of a solid oxide fuel cell, a method for producing the bonding material, and a solid having a bonding portion using the bonding material. The present invention relates to an oxide fuel cell system and a bonding method using the bonding material.

  A solid oxide fuel cell (SOFC) is a type of fuel cell that has a high power generation efficiency, a low environmental load, and can use various fuels. From this point, it is expected as a next-generation power generation device, and its development is in progress.

The basic structure (cell) of SOFC is that an air electrode (cathode) is formed on one surface of a dense solid electrolyte (eg, a dense membrane layer) made of an oxygen ion conductor, and a fuel electrode (anode) is formed on the other surface. It is configured by being. Both the air electrode and the fuel electrode have a porous structure with good gas diffusibility. Fuel gas (typically H ₂ (hydrogen) gas or fuel gas such as methane) is supplied to the fuel electrode side of the solid electrolyte, and O ₂ (oxygen) -containing gas (typically air) is supplied to the air electrode side. ) Is supplied.

In recent years, as SOFC has been put into practical use, there is an increasing demand for reducing gas leakage (gas leakage) in a fuel cell system (power generation system) including a plurality of SOFCs (fuel cell). The gas leak may be caused by a connection between cells when a power generation system (typically provided with a stack structure) prepared by connecting a plurality of the cells, or other connection member (for example, fuel gas) is provided. And gas pipes for supplying O ₂ -containing gas). The gas leak is a problem to be solved in order to improve the durability and reliability of the SOFC, because it causes a reduction in fuel gas utilization efficiency and local heat distribution unevenness. Therefore, excellent airtightness is required for the bonding material forming the bonding portion.

Here, an example of the joining portion (joining material) is described in Patent Document 1. The joint in this document is formed of a joint material in which leucite crystals are precipitated in a glass matrix. For this reason, the joining part described in the said literature does not flow easily in the temperature range of 800 degreeC or more (for example, 800-1000 degreeC), and there is no possibility that the glass which comprises a joining part may flow out. Thus, in order to realize the improvement of the mechanical strength of the joint including glass, it is effective to deposit a crystal structure in the glass matrix.
Moreover, the thing of patent documents 2-5 is mentioned as another example regarding the junction part of SOFC.

JP 2009-199970 A Japanese Patent Laid-Open No. 11-154525 JP 2004-039573 A Special table 2008-527680 Special table 2008-529256

  By the way, in the SOFC, the internal temperature may rise to 1100 ° C. or more in a rapid start-up, local gas leak, or an excessive temperature rise condition evaluation test assuming these situations. When exposed to such a high temperature environment, the glass constituting the joint may be softened or crystals may be dissolved in the glass matrix. In the softened glass, crystals flow, and the crystals aggregate or settle, so that partial unevenness can occur in the thermal expansion coefficient of the bonding material. In addition, when the crystal is dissolved in the glass matrix, the thermal expansion coefficient of the bonding material is lowered, which is not preferable. Since the joining material for SOFC is manufactured in consideration of the thermal expansion coefficient of the target member to be joined, cracks are likely to occur when the thermal expansion coefficient is reduced or uneven, and gas leakage may occur. Absent.

  The present invention has been made in view of the above-described problems, and is a joint that can constitute a SOFC joint that is less likely to cause a decrease in thermal expansion coefficient and unevenness even after being exposed to a high-temperature environment and that can prevent gas leakage. The purpose is to provide materials. Another object is to provide a fuel cell system including a SOFC (cell) or a SOFC in which a joining portion is formed using such a joining material.

In order to achieve the above object, a bonding material for a solid oxide fuel cell system provided by the present invention will be described. In the following description, “thermal expansion coefficient” is a value that can be measured using a thermomechanical analyzer (TMA), for example, in the range of room temperature (25 ° C.) to 500 ° C. (or 1000 ° C.). The average value when measured with can be used. The “average particle diameter” refers to D ₅₀ (median diameter) in the particle size distribution to be measured. Such D ₅₀ is, for example, can be easily measured by a conventionally known laser diffraction method, the particle size distribution measurement apparatus based on light scattering method or the like.

  In the present specification, the solid oxide fuel cell system (hereinafter referred to as “SOFC system”) refers to a structure (system) that generates power mainly by SOFC, and is a fuel cell (ie, a solid unit) that is a minimum unit. A stack comprising a plurality of components of a fuel cell having an electrolyte, a fuel electrode, and an air electrode) (ie, an assembly in which a plurality of cells are connected to each other), and an interconnector interposed between the cells when the stack is formed (Separator) is a term encompassing a structure including a gas pipe for supplying a fuel gas or an oxygen-containing gas to the cell or stack. Therefore, typical examples of the members constituting the SOFC system mentioned here include SOFC components (that is, solid electrolyte, fuel electrode, air electrode), gas pipes and interconnectors that can be connected to the SOFC. .

The joining material provided by the present invention is for joining members constituting the SOFC system, and is composed mainly of glass. One aspect of such a bonding material is characterized in that cristobalite crystals and / or leucite crystals are precipitated in the glass matrix, and the content of the above crystals is 0.5 to 5 vol% with the entire bonding material being 100 vol%. And Preferably, the thermal expansion coefficient is 9 × 10 ^{−6 to} 12 × 10 ⁻⁶ / K.

The bonding material having the above-described configuration is prepared such that the crystal content relative to the entire bonding material is a relatively low content of 0.5 to 5 vol% as described above. By including such a crystal structure at a ratio of 0.5 vol% or more, high airtightness (sealing performance) and mechanical strength can be realized in a joint formed from the joining material, and a high-temperature environment (for example, 1100 to 1200). The ratio of crystals dissolved in the glass matrix is small even when exposed to (° C.), and the thermal expansion coefficient is hardly lowered by the dissolution of crystals. Therefore, according to the bonding material of this configuration, it is possible to form a bonded portion that maintains stable mechanical strength (bonding strength) even in a high-temperature environment (for example, 1100 to 1200 ° C.).
Moreover, the bonding material disclosed here is prepared so that the thermal expansion coefficient is 9 × 10 ^{−6 to} 12 × 10 ⁻⁶ / K. The coefficient of thermal expansion in this range is a so-called lanthanum chromite oxidation such as zirconia solid electrolytes such as zirconia (YSZ) stabilized with yttria (Y ₂ O ₃ ), LaCrO ₃ , La _0.8 Ca _0.2 CrO _3, etc. This approximates the coefficient of thermal expansion of the main components of the SOFC system, such as an interconnector made of metal such as SUS430. Therefore, it is particularly preferable for joining such materials.
As described above, the bonding material of the present invention has a thermal expansion coefficient suitable for the SOFC system, and the thermal expansion coefficient hardly changes even when exposed to a high temperature environment such as 1000 ° C. to 1200 ° C. have. Therefore, when the joining portion of the SOFC system is formed with the joining material of the present invention, gas leak can be suitably prevented even after the SOFC system is exposed to a high temperature environment.

Moreover, the bonding material according to a preferred embodiment disclosed herein has the following composition in mass ratio in terms of oxide:
SiO ₂ 55~75mass%;
Al ₂ O ₃ 10~20mass%;
Na ₂ O 3~15mass%;
K ₂ O 4~15mass%;
At least one of MgO, CaO, B ₂ O ₃ 0-5 mass%;
Is substantially composed of.
The joint formed by the joining material having such a composition can be closely approximated to a solid electrolyte, an interconnector, or the like having the above composition whose thermal expansion coefficient (coefficient of thermal expansion) is a joining target. Therefore, even if the joint part joined using the joining material of this structure is placed in a high temperature range that is typically in the range of 1000 to 1200 ° C., the joint part (for example, the solid electrolyte and the interconnector). The gas leakage from the sealing part) can be prevented, and high airtightness can be maintained.

Further, the bonding material according to a preferred aspect disclosed herein is a treatment in which the glass in a state where the cristobalite crystal and / or the leucite crystal is deposited is heated and a part of the crystal is re-dissolved in the glass matrix. As a result, the content of the crystal is adjusted.
Such a re-dissolution treatment is suitable for bringing the content of the crystal into a range of 0.5 to 5 vol%.
The crystals in the glass that has undergone the remelting process have a smaller particle size due to melting, so that the fine glass is not affected by the crystals that are present compared to the glass that has not been remelted. Powder can be easily formed (pulverized). Such a bonding material mainly composed of fine glass powder can be easily applied in a thin line shape to a bonding target, for example, and therefore, a bonding portion having a fine shape can be formed with high accuracy.

Moreover, this invention provides the manufacturing method of the said joining material as another side surface.
That is, the bonding material manufacturing method disclosed herein prepares a glass material containing cristobalite crystals and / or leucite crystals; the glass material is heated, and a part of the crystals is redissolved in the glass matrix. By adjusting the content of the crystal to 0.5 to 5 vol% when the entire bonding material is set to 100 vol%.
According to this manufacturing method, the glass material containing crystals is heated to re-dissolve a part of the crystals in the glass matrix, whereby the crystal content in the glass matrix is reduced to 0.5 to 5 vol. %. As a result, it is possible to suitably manufacture a bonding material for an SOFC system that has a thermal expansion coefficient that is unlikely to cause cracks and that can form a joint that is difficult to change even after being exposed to a high-temperature environment. be able to.
In a preferred embodiment, the glass material has the following composition in terms of mass ratio in terms of oxide:
SiO ₂ 55~75mass%;
Al ₂ O ₃ 10~20mass%;
Na ₂ O 3~15mass%;
K ₂ O 4~15mass%;
At least one of MgO, CaO, B ₂ O ₃ 0-5 mass%;
A glass material substantially composed of is prepared.
By using a glass material having such a composition, a joining material whose thermal expansion coefficient (thermal expansion coefficient) closely approximates that of the solid electrolyte or interconnector having the above composition to be joined can be preferably produced.

Moreover, this invention provides the SOFC system by which the junction part was formed using the said joining material as another side surface. That is, the SOFC system disclosed here is configured to include one or a plurality of fuel cells each including a fuel electrode, an air electrode, and a solid electrolyte, and is connected to each other or between the cells and the cells. The joint part with the connecting member is mainly composed of the above-mentioned joining material, that is, glass, cristobalite crystals and / or leucite crystals are precipitated in the glass matrix, and the entire joining material is 100 vol%. The content rate is 0.5 to 5 vol%, and the thermal expansion coefficient is 9 × 10 ^{−6 to} 12 × 10 ⁻⁶ / K. In addition, as above-mentioned as a typical example of a connection member, gas piping and an interconnector are mentioned.
In the SOFC system having such a configuration, since the joining portion is formed of the joining material, gas leakage from the joining portion can be prevented even when exposed to a high temperature range of 1100 ° C. to 1200 ° C., for example. For this reason, high heat resistance (seal performance) is realizable.
In a particularly preferred embodiment, the joint has the following composition in mass ratio in terms of oxide:
SiO ₂ 55~75mass%;
Al ₂ O ₃ 10~20mass%;
Na ₂ O 3~15mass%;
K ₂ O 4~15mass%;
At least one of MgO, CaO, B ₂ O ₃ 0-5 mass%;
Is substantially composed of.
Since the joint portion having such a composition closely approximates the solid electrolyte, interconnector, or the like having the thermal expansion coefficient (thermal expansion coefficient) to be joined, a particularly high mechanical strength (joining strength) must be realized. Can do.

Moreover, this invention provides the method of joining this cell which comprises the above-mentioned SOFC system as another aspect, or this cell, and the connection member connected to this cell.
That is, in such a joining method, any one of the joining materials disclosed herein is applied to the joint portions between the cells or between the cells and the connection member; the joining material flows out from the joint portions. Forming a bonding portion made of a bonding material at the bonding portion by firing in a temperature range that does not.

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

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than the matters specifically mentioned in the present specification (for example, the structure of the bonding material and the manufacturing method of the bonding material) and the matters necessary for the implementation of the present invention (for example, the cells constituting the SOFC system, The detailed stack construction method and the like) can be grasped as a design matter of a person skilled in the art based on the prior art in the field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

The bonding material for SOFC system according to the present invention (hereinafter simply referred to as “bonding material”) is for bonding members constituting the SOFC system, and is mainly composed of glass. Also, cristobalite crystals and / or leucite crystals are precipitated in the glass matrix of the bonding material. And the crystal content rate of the said joining material exists in the range of 0.5-5 vol% when the whole joining material is 100 vol%. Furthermore, the thermal expansion coefficient of this bonding material is in the range of 9 × 10 ^{−6 to} 12 × 10 ⁻⁶ / K. The bonding material of the present invention has these characteristics, and the content and composition of other components can be determined in light of various standards.

  As the glass constituting the bonding material disclosed herein, it is possible to use a glass that softens at the operating temperature of the SOFC system. The operating temperature range of the SOFC system is, for example, about 600 ° C to 1200 ° C, typically about 700 ° C to 1000 ° C. On the other hand, the softening point of the glass is, for example, about 500 ° C to 1000 ° C, typically about 600 ° C to 900 ° C. The softening point of the glass can be adjusted by adding (or increasing) a component that increases the softening point.

The glass constituting the bonding material disclosed herein includes, for example, SiO ₂ , Al ₂ O ₃ , Na ₂ O, K ₂ O and optional additives (MgO, CaO, B ₂ O _3, etc.) as constituent components. It is good to be out. Proportion of the constituents, the mass ratio of the oxide _{equivalent, SiO 2: 55~75mass%, Al} 2 O 3: 10~20mass%, Na 2 O: 3~15mass%, K 2 O: 4~15mass% It is good to be. In addition, the optional additive may contain 0 to 5 mass% of at least one of MgO, CaO, and B ₂ O ₃ .

Of the above-described constituent components, SiO ₂ is a component constituting cristobalite crystal and leucite crystal, which will be described in detail later, and is the main component of glass constituting the skeleton of the glass matrix. If the SiO ₂ content is too high in the glass, the softening point of the glass becomes too high, which is not preferable. On the other hand, if the SiO ₂ content is too low, the amount of crystals deposited becomes too small, and the water resistance and chemical resistance decrease, which is not preferable. From this, the SiO ₂ content in the glass is preferably in the range of 55 to 75 mass% (preferably 58 to 72 mass%, typically 62 to 69 mass%) with respect to the entire glass.

Al ₂ O ₃ is a component constituting the leucite crystal, and is a component involved in adhesion stability by controlling the fluidity of the glass. If the Al ₂ O ₃ content is too low, the adhesion stability is lowered, so that formation of a glass layer (glass matrix) having a uniform thickness may be impaired, and the amount of crystal precipitation is reduced, 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. From this, the Al ₂ O ₃ content in the glass is preferably in the range of 10 to 20 mass% (preferably 10 to 15 mass%, typically 10 to 13 mass%) with respect to the entire glass.

K ₂ O is a component that constitutes the leucite crystal, and is a component that enhances the thermal expansion coefficient (thermal expansion coefficient) of glass together with other alkali metal oxides (typically Na ₂ O). When the K ₂ O content is too low, the amount of leucite crystal precipitation decreases. Further, there is a possibility that K 2 _O and Na 2 _O content is too low, the thermal expansion coefficient becomes too low. On the other hand, if the contents of K ₂ O and Na ₂ O are too high, the thermal expansion coefficient becomes excessively high, which is not preferable. From this, the Na ₂ O content in the glass is preferably in the range of 3 to 15 mass% (preferably 5 to 13 mass%, typically 9 to 12 mass%) with respect to the entire glass. The content of _{K 2} O in the glass, 4～15Mass% based on the entire glass (preferably 4～14Mass%, typically 6~12mass%) may it is. Furthermore, the total of K ₂ O and Na ₂ O is particularly preferably 8 to 25 mass% (preferably 10 to 20 mass%) with respect to the entire glass.

  Moreover, MgO, CaO, etc. which are alkaline-earth metal oxides can be arbitrarily added to the glass disclosed here. The thermal expansion coefficient can be adjusted by adding the optional additive into the glass. For example, MgO is a component capable of adjusting the viscosity at the time of glass melting, and CaO is a component capable of improving the wear resistance by increasing the hardness of the glass matrix. By incorporating these components, the glass matrix is composed of a multi-component system, so that the chemical resistance can be improved. The content of these oxides in the entire glass composition is in the range of 0 (no addition) to 5 mass% (preferably 1.0 to 4.5 mass%, typically 1.5 to 4 mass%), respectively. There should be.

Another optional additive component is B ₂ O ₃ . 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 glass composition is in the range of 0 (no addition) to 5 mass% (preferably 1.0 to 4.5 mass%, typically 1.5 to 3 mass%). Good.

In addition, the glass disclosed herein includes components other than those described above that are not essential in the practice of the present invention (eg, ZnO, Li ₂ O, Bi ₂ O ₃ , SrO, SnO, SnO ₂ , CuO, Cu ₂ O, TiO ₂ , ZrO ₂ , La ₂ O _3, etc.) may be included.

In the bonding material described herein, cristobalite crystals in the glass matrix (SiO ₂₎ and / or leucite crystal (KAlSi ₂ O ₆ or _{4SiO 2 · Al 2 O 3 ·} K 2 O) is precipitated. In the glass disclosed here, cristobalite crystals and / or leucite crystals may be precipitated in the glass matrix, and the presence or absence of other crystals does not matter.

  Here, the bonding material is characterized in that the crystal content is 0.5 to 5 vol%. The crystal content in the present specification refers to the ratio of crystals precipitated in the glass matrix with respect to the entire bonding material, and can be measured using a powder XRD method. The crystal content with respect to the bonding material is preferably about 0.5 to 4 vol%, more preferably about 0.5 to 3 vol%, typically about 1 to 3 vol%, for example, 2.5 ±. It is good that it is about 0.4 vol%. Thus, by including a crystal structure in a proportion within the above-described range, it is possible to achieve high airtightness (sealing performance) and mechanical strength in a joint formed from the joint material, and a high-temperature environment (for example, Even when exposed to 1100-1200 ° C., the proportion of crystals dissolved in the glass matrix is small, and the thermal expansion coefficient is hardly lowered due to dissolution of crystals.

Moreover, the bonding material disclosed here has a thermal expansion coefficient of 9 × 10 ^{−6 to} 12 × 10 ⁻⁶ / K. The thermal expansion coefficient is more preferably in the range of 9 × 10 ^{−6 to} 11 × 10 ⁻⁶ / K, and typically 9 × 10 ^{−6 to} 10.5 × 10 ⁻⁶ / K. It should be within the range. The thermal expansion coefficient in the above range approximates the thermal expansion coefficient of components for SOFC systems such as interconnectors made of zirconia-based solid electrolytes such as YSZ, lanthanum chromite oxides, and metals such as SUS430. It can be suitably used for SOFC systems.

Next, a method for manufacturing the bonding material will be described.
The manufacturing method of the bonding material disclosed herein includes (1) preparing a glass material containing cristobalite crystals and / or leucite crystals; (2) heating the glass material, Adjusting the crystal content to 0.5 to 5 vol% when the entire bonding material is 100 vol% by re-dissolving in the glass matrix. In addition, about the other process in this manufacturing method, the process similar to the manufacturing method of the conventional joining material for SOFC systems is applicable.
As described above, the bonding material obtained by the above manufacturing method has a thermal expansion coefficient that hardly causes cracks when used in an SOFC system, and the thermal expansion coefficient changes even after being exposed to a high temperature environment. It has the advantage of being difficult to do.

  Here, first, (1) a glass material containing cristobalite crystals and / or leucite crystals (hereinafter referred to as “crystal-containing glass material”) is prepared. In preparing the crystal-containing glass material, for example, a crystal-containing glass material may be prepared from a glass raw material, or a glass material on which crystals are preliminarily deposited may be purchased. Hereinafter, the case where a crystal containing glass material is created from a glass raw material is demonstrated.

  First, the glass raw material which comprises a joining material is prepared. Here, compounds for obtaining various oxide components constituting the bonding material (for example, industrial products, reagents, various mineral raw materials including oxides, carbonates, nitrates, complex oxides, etc., containing each component) If necessary, other additives are prepared as glass raw material powder. The average particle size of each powder to be prepared is preferably about 1 μm to 10 μm. Each of these compounds and additives are put into a mixer such as a dry or wet ball mill at a predetermined mixing ratio and mixed for several hours to several tens of hours. The admixture (powder) thus obtained is dried, placed in a refractory crucible, and heated and melted under suitable high temperature conditions (typically 1000 ° C. to 1500 ° C.). Thereby, glass is obtained from the glass raw material.

  Next, the obtained glass is pulverized to an appropriate size (particle size) to produce glass powder. The obtained glass powder is preferably subjected to classification treatment. The particle size (average particle size) of the glass powder is not particularly limited as long as the particle size 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.

And the crystallization process is performed with respect to the said glass powder. As this crystallization treatment, for example, the above mixed powder is heated from room temperature to about 100 ° C. at a rate of about 1 to 5 ° C./min and held at a temperature range of 800 ° C. to 1000 ° C. for about 30 minutes to 60 minutes. The process of doing is mentioned. By carrying out the crystallization treatment, crystals such as cristobalite crystals and leucite crystals are precipitated in the glass matrix, and a crystal-containing glass material is obtained.
The crystal-containing glass material thus obtained may be optionally shaped into a desired form. For example, a powdery crystal-containing glass material having a desired average particle diameter (for example, 0.1 μm to 10 μm) can be obtained by pulverizing with a ball mill or appropriately sieving (classifying).

Next, in the manufacturing method disclosed herein, (2) the glass material (crystal-containing glass material) is heated, and a part of the crystals is re-dissolved in the glass matrix (re-dissolution treatment is performed). As the said remelting process, it is good to implement by heating the said crystal | crystallization containing glass material at 900 to 1500 degreeC (preferably 1000 to 1300 degreeC, typically about 1100 degreeC), for example. The heating time at this time may be set to 20 minutes to 2 hours (preferably 30 minutes to 1 hour, typically about 45 minutes). When this re-dissolution treatment is carried out, the crystal precipitated in the crystal-containing glass material is dissolved again in the glass matrix, and the glass material (hereinafter, referred to as “crystal content” adjusted to a range of 0.5 to 5 vol%). (Referred to as “remelted glass material”). At this time, the crystal network formed in the crystal-containing glass material becomes pseudo-amorphous, but the ionic bondability remains between the atoms constituting the glass, so that the crystal content decreases. The thermal expansion coefficient is also maintained. For this reason, the coefficient of thermal expansion is adjusted to 9 × 10 ^{−6 to} 12 × 10 ⁻⁶ / by adjusting the crystal content of the crystal-containing glass material to be subjected to the remelting treatment, the heating temperature and the heating time in the remelting treatment. While maintaining K, the crystal content can be adjusted to 0.5 to 5 vol%.

  The remelted glass material obtained as described above is used as a bonding material for SOFC systems by being prepared by various methods. For example, the remelted glass material is pulverized and classified again to prepare a remelted glass material powder. In this case, it is good to grind | pulverize so that powder with an average particle diameter of about 0.1 micrometer-10 micrometers may be obtained. Then, an appropriate amount of water is added to the powder of the remelted glass material and mixed using a ball mill similar to the above, and then subjected to a drying process for a predetermined time, whereby a powdery bonding material is obtained.

The bonding material thus obtained can be used in the same manner as a conventional bonding material (typically prepared in a paste form (slurry) and applied to a connection portion (bonded portion) to be bonded. can do). For example, if a paste-like bonding material is to be adjusted, the above-mentioned remelted glass powder may be mixed with an appropriate binder or solvent. 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 joining material paste.

  Examples of the solvent that can be contained in the bonding material 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 joining material paste is preferable.

The bonding material can be used to form a bonded portion of the SOFC system. Such an SOFC system includes, for example, one or more fuel cells (hereinafter simply referred to as “cells”) each including a fuel electrode, an air electrode, and a solid electrolyte. The bonding material is a connection member connected between the cells or between the cells (for example, a gas pipe for supplying gas to the cells, or an interconnector interposed between the cells in a stack connecting the cells) Etc.) are used to form a joint.
Hereinafter, as an example of the use of the bonding material of the present invention, an SOFC system in which the cell and the gas pipe are bonded with the bonding material will be described with reference to FIG. FIG. 1 is a cross-sectional view of an SOFC system comprising an anode supported cell and a gas pipe joined to the cell. In the drawings, members / parts having the same action are denoted by the same reference numerals, but the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect actual dimensional relationships.

  The SOFC system 100 disclosed here has a cell 50 including a solid electrolyte 14, a fuel electrode 12, and an air electrode 16. The cell 50 may be prepared according to a conventional method of manufacturing a fuel cell, and does not require special processing. That is, the solid electrolyte 14, the fuel electrode 12, and the air electrode 16, which are constituent members of the cell 50 disclosed herein, can be formed by various conventionally used methods.

As the solid electrolyte 14, a zirconia solid electrolyte may be 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. A fuel electrode 12 and an air electrode 16 are formed on both surfaces of the solid electrolyte 14.

The fuel electrode 12 and the air electrode 16 may be the same as those used in conventional fuel cells and are not particularly limited. For example, as the fuel electrode 12, a cermet of nickel (Ni) and YSZ, a cermet of ruthenium (Ru) and YSZ, and the like are preferably employed. As the air electrode 16, a lanthanum cobaltate (LaCoO ₃ ) -based or lanthanum manganate (LaMnO ₃ ) -based perovskite oxide is preferably used. Porous bodies made of these materials can be used as the fuel electrode 12 and the air electrode 16, respectively.

The cell 50 provided with the said structure can be constructed | assembled as follows, for example.
First, the fuel electrode 12 is produced as a support base (support). Here, a slurry-like molding material for a fuel electrode comprising a predetermined cermet material (for example, a YSZ powder having an average particle size of about 0.1 μm to 10 μm, a NiO powder having an average particle size of about 1 μm to 10 μm, a binder, a dispersant, a solvent). To prepare. Next, using this molding material, a molded body of the fuel electrode 12 is produced by, for example, extrusion molding. Here, the shape of the molded body of the fuel electrode 12 may be a sheet shape (or a flat plate shape), a hollow box shape having a hollow portion (gas channel) for allowing fuel gas to flow into the fuel electrode, or Examples thereof include a hollow flat shape (flat tubular shape). In the cell 50 shown in FIG. 1, a sheet-like fuel electrode 12 is formed.

  Next, a material for the solid electrolyte 14 is prepared. That is, a predetermined material (for example, 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 the solid electrolyte 14 in a slurry (paste) form. The molding material for the solid electrolyte 14 is printed and formed on the fuel electrode 12 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). A solid electrolyte membrane 14 is formed. The solid electrolyte membrane 14 supported by the fuel electrode 12 is dried and then fired at a firing temperature of 1200 ° C. to 1400 ° C. in the atmosphere. As a result, a dense solid electrolyte membrane 14 is formed on the fuel electrode 12.

Next, a material for the air electrode 16 is prepared. That is, a molding material for the slurry-like air electrode 16 made of 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. The molding material for the air electrode 16 is printed and formed on the surface of the solid electrolyte 14 with 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 extreme layer (film) 16 is formed. After drying this, it is fired at a firing temperature of 1000 ° C. to 1200 ° C. in the air. In this way, the air electrode 16 is formed on the solid electrolyte membrane 14.
Through the above steps, the anode-supported cell 50 having a structure in which the fuel electrode 12, the solid electrolyte membrane 14, and the air electrode 16 are laminated in this order is manufactured.

  Next, the gas pipe 20 that supplies fuel gas to the cell 50 will be described. The gas pipe may be the same as a conventional gas pipe used for supplying gas to a cell (or a stack to which the cells are connected), and is not particularly limited. For example, a gas pipe made of a dense body of a zirconia-based oxide such as YSZ, which is the same material as the solid electrolyte, can easily be joined to the solid electrolyte and can be suitably used. The shape and size of the gas pipe are appropriately set according to the size of the cell (stack) to be connected and the size of the joined portion.

  The gas pipe 20 can be manufactured by the same method as the conventional manufacturing method, 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 is fired in an appropriate temperature range (for example, 1300 ° C. to 1600 ° C.) in the atmosphere, and the tubular gas pipe 20 can be manufactured. Moreover, you may use what is marketed for SOFC systems, such as SUS430 metal, for the gas pipe 20.

When the bonding material disclosed here is used, the SOFC system 100 can be constructed by bonding the cell 50 and the gas pipe 20 together.
As shown in FIG. 1, in a state where one connection surface 13 of the fuel electrode 12 in the cell 50 and the end surface 21 of the gas pipe 20 are in contact with each other, the bonding material is covered so as to cover the contact surface (bonding surface). 1 is given. Furthermore, here, the bonding material 1 is applied so as to extend beyond the contact surface to the end of the solid electrolyte membrane 14. At this time, the bonding material 1 closes the gap between the gas pipe 20 and the solid electrolyte membrane 14 and is exposed between the gas pipe 20 and the solid electrolyte membrane 14. It is preferable that it is provided so as to cover the end portion. The same applies to the other connection surface 15 of the fuel electrode 12 and the end surface 23 of the gas pipe 20. By providing the bonding material 1 in this manner, a gap (that is, a part of the porous fuel electrode 12 that can be exposed) that may occur at the bonding portion between the solid electrolyte membrane 14 and the gas pipe 20 is completely formed by the bonding material 1. It is blocked. In such a state, the bonded portion 1 is formed by firing in a temperature range (for example, about 800 ° C. to 900 ° C.) at which the bonding material 1 does not flow out of the bonded portion, and the gas pipe 20 and the cell 50 are bonded and connected. Can be made.
Since the joint 1 formed by such joining has a thermal expansion coefficient approximate to that of the joining target (here, the fuel electrode 12, the gas pipe 20, and the solid electrolyte membrane 14), the operation of the SOFC system 100 is performed. Therefore, high airtightness and strength can be maintained even if the temperature changes. Furthermore, the joint 1 disclosed here is formed of a joining material that can maintain high hermeticity and strength even after being exposed to a high temperature environment (eg, 1200 ° C. or higher), so that the SOFC system 100 is overheated. Even after this, gas leakage from the joint surface can be suitably prevented.

  In the above, the SOFC system 100 which joined the junction part of the cell 50 and the gas pipe 20 using the joining material of this invention was demonstrated. However, the application of the bonding material in the SOFC system is not limited to this. For example, the bonding material disclosed herein can also be used when building a stack in which cells are bonded together. In this case, the bonding material is used, for example, to form a bonding portion between an interconnector (separator) and a cell that can be disposed between the cells when a stack is constructed.

The interconnector is a member that is disposed between a plurality of cells and electrically connects the cells. As the interconnector, a lanthanum chromite oxide that physically shuts off an oxygen supply gas (for example, air) and a fuel gas and has electronic conductivity is used.
As such a lanthanum chromite oxide, an oxide represented by the general formula: La _(1-x) Ma _(x) Cr _(1-y) Mb _(y) O ₃ can be used. Ma and Mb in the formula are the same or different one or more alkaline earth metals, and x and y are 0 ≦ x <1 and 0 ≦ y <1, respectively. Preferable examples include LaCrO ₃ or an oxide in which Ma or Mb is calcium (lanthanum calcia chromite), for example, 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, a heat resistant metal such as SUS430 can be used for the interconnector.

The junction between the interconnector and the cell will be described with reference to FIG.
As shown in FIG. 2, the interconnectors 18 </ b> A and 18 </ b> B are joined to the solid electrolyte 14 of the cell 50, and the joined portion 1 formed from the joining material is formed at the joined portion. An oxygen supply gas (typically air) flow path 2 is formed between the air electrode 16 and the interconnector 18A on the air electrode 16 side, and the fuel electrode 12 and the interconnector 18B on the fuel electrode 12 side are connected. A fuel gas (hydrogen supply gas) flow path 4 is formed therebetween. These gas flow paths 2 and 4 may be pipes (tubular or tubular members) formed from 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 described above, in the SOFC system 110 as shown in FIG. 2, the gap that may be generated between the solid electrolyte 14 and the interconnectors 18 </ b> A and 18 </ b> B is blocked by the joint portion 1 made of the joining material. For this reason, even after the SOFC system 110 is exposed to a high temperature environment, high airtightness and strength can be maintained in the joint 1, and gas leakage that may occur from a gap that may occur between the solid electrolyte 14 and the interconnectors 18 </ b> A and 18 </ b> B. This can be preferably prevented.

  EXAMPLES Next, examples relating to the present invention will be described, but the present invention is not intended to be limited to those shown in the following examples. In the following examples, bonding materials (samples 1 to 10) prepared by different processes were prepared, and the performance of each sample was evaluated.

<Sample 1>
Hereinafter, the process of creating Sample 1 will be described. 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 are respectively The mixing ratio, that is, in terms of oxide, SiO ₂ is 63.3 mass%, Al ₂ O ₃ is 11.4 mass%, Na ₂ O is 9.7 mass%, K ₂ O is 11.9 mass%, and MgO is The mixture was mixed at a blending ratio such that 0.1% by mass, CaO was 3.7% by mass, and B ₂ O ₃ was 0.1% by mass to obtain a glass raw material powder.
Next, the glass raw material powder was melted in a temperature range of 1400 ° C. to 1500 ° C. to form glass, and the glass was pulverized until the average particle size became about 3 μm to produce a glass powder. And the cristobalite crystal and / or the leucite crystal are precipitated in the glass matrix by heating the glass powder in a temperature range of 800 ° C. to 1000 ° C. for 30 minutes to 60 minutes and performing a crystallization treatment. A crystal-containing glass material was obtained.
Next, a remelting treatment (1100 ° C., 30 to 60 minutes) was performed on the powder obtained by pulverizing the crystal-containing glass material to obtain a remelted glass material. Then, the remelted glass material is pulverized and classified to obtain a powder having an average particle diameter of about 2 μm. The remelted glass material powder is kneaded with a binder, a dispersant, and a solvent, and bonded in a paste form. A material (Sample 1) was prepared.

<Sample 2>
Here, 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 are respectively mixed in the following compounding ratio, that is, oxide conversion SiO ₂ is 65.8 mass%, Al ₂ O ₃ is 11.9 mass%, Na ₂ O is 10.2 mass%, K ₂ O is 9.3 mass%, MgO is 0.5 mass%, CaO. Was mixed at a blending ratio so as to be 2.9% by mass to obtain a glass raw material powder. Here, B ₂ O ₃ was not added. And sample 2 was created by the process similar to the said sample 1 except the compounding ratio of the said component.

<Sample 3>
Here, in terms of oxide, SiO ₂ is 67.3 mass%, Al ₂ O ₃ is 12.3 mass%, Na ₂ O is 10.5 mass%, K ₂ O is 7.6 mass%, and CaO is 2 The mixture was mixed at a blending ratio of 4% by mass and 0.1% by mass of B ₂ O ₃ to obtain a glass raw material powder. Here, no MgO was added. And sample 3 was created in the same process as sample 1 except for the blending ratio of the components.

<Sample 4>
Here, in terms of oxide, SiO ₂ is 68.5% by mass, Al ₂ O ₃ is 12.5% by mass, Na ₂ O is 10.6% by mass, K ₂ O is 6.5% by mass, and MgO is 0%. 0.5% by mass, CaO was 2.0% by mass, and B ₂ O ₃ was mixed at a mixing ratio of 0.5% by mass to obtain a glass raw material powder. And sample 4 was created by the process similar to the said sample 1 except the compounding ratio of the said structural component.

<Sample 5>
Here, in terms of oxide, SiO ₂ is 58.5% by mass, Al ₂ O ₃ is 12.0% by mass, Na ₂ O is 11.5% by mass, K ₂ O is 13.5% by mass, and MgO is 0%. The glass raw material powder was obtained by mixing at a blending ratio of 0.5 mass%, CaO 4.5 mass%, and B ₂ O ₃ 0.5 mass%. And sample 5 was created by the process similar to the said sample 1 except the compounding ratio of the said component.

<Sample 6>
Here, in terms of oxide, SiO ₂ is 71.0% by mass, Al ₂ O ₃ is 12.5% by mass, Na ₂ O is 10.6% by mass, K ₂ O is 4.5% by mass, and MgO is 1%. 0.02 mass%, CaO was 1.5 mass%, and B ₂ O ₃ was mixed at a blending ratio of 0.5 mass% to obtain a glass raw material powder. And sample 6 was created by the process similar to the said sample 1 except the compounding ratio of the said component.

<Sample 7>
Here, a sample 7 of the bonding material was prepared without performing the remelting treatment. Specifically, a glass powder made of a glass raw material having the same blending ratio as that of Sample 1 was prepared, and crystallization treatment was performed on the glass powder to obtain a crystal-containing glass material. Then, without dissolving the crystal-containing glass material again, the sample 7 was prepared by kneading with a binder, a dispersant, and a solvent.

<Sample 8>
Here, the glass powder which consists of a glass raw material of the same compounding ratio as the sample 4 was created, the crystallization process was implemented with respect to the said glass powder, and the crystal-containing glass material was obtained. And the sample 8 was prepared by knead | mixing with a binder, a dispersing agent, and a solvent, without implementing a remelting process to crystal-containing glass material.

<Sample 9>
Here, a glass powder made of a glass raw material having the same blending ratio as that of sample 1 is prepared, and the glass powder is kneaded with a binder, a dispersant, and a solvent without performing crystallization treatment and remelting treatment. 9 was prepared.

<Sample 10>
Here, a glass powder made of a glass raw material having the same blending ratio as sample 3 is prepared, and the glass powder is kneaded with a binder, a dispersant, and a solvent without performing crystallization treatment and remelting treatment. 10 was prepared.

<Measurement of crystal content>
With respect to the ten types of bonding materials (samples 1 to 10), the crystal content was measured when the bonding material was 100 vol%. Specifically, the crystal content of each sample was measured by a powder XRD method using vtrax 18-TTR3-300 manufactured by RIGAKU. The measured crystal content of each sample is shown in Table 1.

  As described in Table 1, in Samples 1 to 6 in which both the crystallization treatment and the remelting treatment were performed, the crystal content was 5.0 mass% or less. Moreover, in the samples 7 and 8 which performed only the crystallization process, the crystal content rate became 10 mass% or more. In addition, in Samples 9 and 10 where neither the crystallization treatment nor the remelting treatment was performed, there was no crystal structure.

  Next, the specimen 200 of the SOFC system was constructed using each of the bonding materials (samples 1 to 10), and the performance of the specimen 200 was evaluated.

<Construction of SOFC system>
8 mol% yttria-stabilized zirconia (YSZ) powder (average particle size: about 1 μm), nickel oxide (NiO) powder, binder (polyvinyl brachil: PVB) were added to a solvent (toluene) and kneaded to form a slurry (or A fuel electrode molded body precursor in the form of paste or ink was prepared. And the said fuel electrode molded object precursor was sheet-formed, and the disk-shaped fuel electrode molded object (diameter 20 mm x thickness about 1 mm) was shape | molded.

  On the other hand, 8 mol% YSZ powder (average particle diameter: about 1 μm) and a binder (PVB) were added to a solvent (toluene) and kneaded to prepare a slurry-like kneaded product. Next, the kneaded material (precursor of the solid electrolyte membrane) was printed on the fuel electrode molded body to form a disk-shaped solid electrolyte membrane (diameter 16 mm × thickness 10 μm to 30 μm). The unfired laminate comprising the fuel electrode compact and the solid electrolyte membrane was dried and fired (firing temperature: 1200 ° C. to 1400 ° C.) to form a fuel electrode (anode).

Next, La _0.6 Sr _0.4 CoO ₃ powder (average particle size: about 1 μm) and a binder (ethyl cellulose) were added to a solvent (terpineol) and kneaded. The kneaded product (precursor of paste-like air electrode) is printed on the solid electrolyte membrane in a disk shape having a diameter of 10 mm × thickness of 5 μm to 30 μm, and then fired (firing temperature: 1000 ° C. to 1200 ° C.). ) To form an air electrode (cathode). As a result, an anode-supported fuel cell 50 composed of the fuel electrode 12, the solid electrolyte membrane 14, and the air electrode 16 as shown in FIG.

  The same binder and solvent as in the case of the solid electrolyte membrane were added to 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 in the air (firing temperature: 1300 ° C. to 1600 ° C.) to produce two tubular gas tubes 22 and 24 (see FIG. 3).

  Next, the anode-supported SOFC cell 50 and the gas pipes 22 and 24 were joined using the joining material (samples 1 to 10), and a specimen 200 of the SOFC system was constructed. Specifically, as shown in FIG. 3, gas pipes 22 and 24 are arranged on both sides of the anode-supported SOFC cell 50, and the solid electrolyte membrane 14 in the cell 50 sandwiched between the gas pipes 22 and 24 The joining material (each sample 1-10) 1 was apply | coated so that the clearance gap between each with the gas pipes 22 and 24 might be plugged up. This was dried at 80 ° C. and then held (fired) at 850 ° C. for 1 hour in the air. Thereby, the gas pipes 22 and 24 and the cell 50 were joined to form the joint 1. In this way, the specimen 200 of the SOFC system was constructed.

<Evaluation of thermal expansion coefficient after high temperature treatment>
Next, with respect to the specimen 200 of the SOFC system in which the gas pipes 22 and 24 and the cell 50 are joined using the 10 types of samples (samples 1 to 10) constructed as described above, the temperature is 1100 ° C. for 10 hours. After the fuel gas and air were supplied (exposed to a high temperature environment), the thermal expansion coefficient of each joint 1 obtained using the paste-like joint material of Samples 1 to 10 was measured. Here, the said thermal expansion coefficient is measured based on the differential expansion method (TMA) in room temperature (25 degreeC)-500 degreeC. The results are shown in Table 1.
As shown in Table 1, Samples 1 to 6 whose crystal content was in the range of 0.5 vol% to 3 vol% had a thermal expansion coefficient of 8 × 10 ⁻⁶ / K even after being exposed to a high temperature environment. Exceeded. In particular, for samples 1-4 was in the range of either ^{9 × 10 -6 / K~12 × 10} -6 / K. On the other hand, the samples 7 to 10 all had a thermal expansion coefficient lower than 8 × 10 ⁻⁶ / K.
Thus, even when glass powder having the same blending ratio is used, the sample whose crystal content is in the range of 0.5 vol% to 3 vol% is high in thermal expansion even after being exposed to a high temperature environment. The coefficient was shown. For this reason, the bonding material having a crystal content of 0.5 vol% to 3 vol% through a process such as remelting treatment maintains a high thermal expansion coefficient even after being exposed to a high temperature environment such as 1100 ° C. It was confirmed that it was possible.

<Gas leak test>
Next, for the specimen 200 of the SOFC system constructed using Samples 1 to 4 and Samples 7 and 8, a leak test was performed to confirm whether a gas leak occurred from the joint 1 after being exposed to a high temperature environment. Specifically, first, air is supplied from the air supply gas pipe 22 side at a pressure of 0.2 Pa and a flow rate of 100 mL / min to the specimen exposed to the high temperature environment, and a pressure of 0.2 Pa. Helium (He) gas as fuel gas was supplied from the fuel gas supply gas pipe 24 side at a lower flow rate of 100 mL / min. Then, the fuel electrode 12 side by gas chromatography (i.e. gas pipe 24 side) to measure the composition of He gas discharged from, N ₂ from the amount of N ₂ gas contained in the He gas, the air from the junction 1 It was evaluated whether or not there was a leak. In addition, this gas leak test was continuously performed for 300 minutes in the environment of 800 degreeC.

The evaluation results of gas leak are shown in Table 2. In Table 2, a case where the leak rate of N ₂ gas (the volume content of N ₂ gas contained in He gas) is 1% or less is indicated as “◯”, and the joint 1 is practically airtight. It was supposed to have. A leak rate of 1% or more was indicated as “x”, and it was determined that a gas leak occurred from the joint 1.

  As shown in Table 2, in Samples 1 to 4, gas leakage from the joint 1 was preferably prevented. That is, it has been found that when the SOFC system joint is formed using the joint material that has been subjected to remelting treatment, the occurrence of gas leakage from the joint is suitably suppressed even after exposure to a high temperature environment.

  According to this example, when the glass was remelted and the bonding material was adjusted using the glass, the crystal content in the bonding material was very small (for example, 0.5 to 5. 0%). Further, it was found that the joint formed by this joining material can secure sufficient airtightness and mechanical strength even after being exposed to a high temperature condition of at least 1200 ° C., and can suitably prevent gas leakage of the SOFC system. For this reason, this joining material can provide the SOFC system excellent in heat resistance.

1 Bonding material (bonding part)
2,4 Gas channel 12 Fuel electrode 14 Solid electrolyte (solid electrolyte membrane)
16 air electrode 18A, 18B interconnector 20 gas pipe 50 cell 100 for solid oxide fuel cell (SOFC) solid oxide fuel cell (SOFC) system

Claims (6)

A joining material mainly composed of glass for joining members constituting a solid oxide fuel cell system,
In the glass matrix, cristobalite crystals and / or leucite crystals are precipitated,
The total content of the bonding material is 100 vol%, and the content of the crystal is 0.5 to 5 vol%,
The thermal expansion coefficient is 9 × 10 ^{−6 to} 12 × 10 ⁻⁶ / K,
The following composition in mass ratio in terms of oxide:
SiO ₂ 55~75mass%;
Al ₂ O ₃ 10~20mass%;
Na ₂ O 3~15mass%;
K ₂ O 4~15mass%;
At least one of MgO, CaO, B ₂ O ₃ 0-5 mass%;
A bonding material characterized in that it is substantially composed of By heating the glass in a state where the cristobalite crystal and / or the leucite crystal is deposited, a part of the crystal is redissolved in a glass matrix, whereby the content of the crystal is reduced. The bonding material according to claim 1, wherein the bonding material is adjusted. A method for producing a glass-based joining material used for joining members constituting a solid oxide fuel cell system,
Preparing a glass material on which cristobalite crystals and / or leucite crystals are deposited;
By heating the glass material and re-dissolving a part of the crystal in the glass matrix, the content of the crystal is adjusted to 0.5 to 5 vol% when the entire glass material is 100 vol%. about;
The manufacturing method of the joining material including this. As the glass material, the following composition in mass ratio in terms of oxide:
SiO ₂ 55~75mass%;
Al ₂ O ₃ 10~20mass%;
Na ₂ O 3~15mass%;
K ₂ O 4~15mass%;
At least one of MgO, CaO, B ₂ O ₃ 0-5 mass%;
The manufacturing method according to claim 3 , wherein a glass material substantially constituted from the above is prepared. A solid oxide fuel cell system having one or a plurality of fuel cells each including a fuel electrode, an air electrode, and a solid electrolyte,
A junction between the cells or the connection member connected to the cell and the cell,
It is mainly made of glass.
In the glass matrix, cristobalite crystals and / or leucite crystals are precipitated,
The total content of the bonding material is 100 vol%, and the content of the crystal is 0.5 to 5 vol%,
The thermal expansion coefficient is 9 × 10 ^{−6 to} 12 × 10 ⁻⁶ / K,
The following composition in mass ratio in terms of oxide:
SiO ₂ 55~75mass%;
Al ₂ O ₃ 10~20mass%;
Na ₂ O 3~15mass%;
K ₂ O 4~15mass%;
At least one of MgO, CaO, B ₂ O ₃ 0-5 mass%;
A solid oxide fuel cell system, characterized in that the solid oxide fuel cell system is constituted by a bonding material substantially composed of The cells constituting a solid oxide fuel cell system having one or a plurality of fuel cells each having a fuel electrode, an air electrode, and a solid electrolyte are joined to each other or to the connection member connected to the cells. A way to
Applying the bonding material according to claim 1 or 2 to the bonding portions between the cells or between the cells and the connection member;
Firing the applied bonding material in a temperature range in which the bonding material does not flow out of the bonding portion, thereby forming a bonding portion made of the bonding material in the bonding portion;
Joining method.

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