JP6305315B2 - Heat-resistant glass sealing material and use thereof - Google Patents

Description

  The present invention relates to a heat resistant glass sealing material. In detail, it is related with the glass sealing material which does not contain an alkali metal component and a magnesium component.

Metal materials are widely used for various devices, equipment, and apparatuses in various industrial fields. For joining members (metal members) made of such metal materials, various joining materials are used depending on the use and joining conditions of the metal members.
For example, in an oxygen ion conduction module used in a high temperature range of about 600 ° C. to 900 ° C., a metal member (for example, a metal pipe) and a ceramic member (for example, an oxygen separation membrane or a solid electrolyte) constituting the oxygen ion conduction module, Must be hermetically sealed and joined. In such applications, bonding materials having the following characteristics are frequently used.
(1) Appropriate viscosity (meltability) at the sealing bonding temperature (softening point).
(2) The coefficient of thermal expansion is similar to or slightly lower than that of the member to be joined (metal member or ceramic member).
(3) Excellent heat resistance and durability in the operating temperature range (for example, 600 ° C to 900 ° C).
Patent documents 1-6 are mentioned as prior art literature relevant to this. For example, Patent Documents 1 to 3 disclose glass bonding materials containing an alkali metal component (for example, at least one of Li, Na, and K). Patent Document 4 discloses a glass bonding material in which MgO—SiO ₂ crystals are precipitated in a glass matrix.

JP 2010-184826 A JP 2009-199970 A JP 2003-238201 A JP, 2014-114168, A JP 2012-174664 A Special table 2010-524193 gazette

As described in the above-mentioned patent documents, glass meltability at the time of sealing and bonding can be improved by including an alkali metal component in the glass bonding material. Moreover, the thermal expansion coefficient of the sealing joint can be increased. However, according to the study by the present inventors, in applications where the operating temperature is in a high temperature range, the alkali metal element component diffuses into the metal member, and the heat resistance and durability of the sealed joint portion may decrease.
Further, the glass bonding material as described in Patent Document 6 is difficult to adjust the glass bonding material to an appropriate high-temperature viscosity, and in some cases, the glass meltability at the time of sealing bonding is lowered and the operation is difficult. In some cases, the shape of the sealed joint portion cannot be maintained well, and the hermeticity of the sealed joint portion may be lowered.
Under such circumstances, there is a demand for a glass sealing material that does not contain an alkali metal component and a magnesium component and has the above-described characteristics.

  This invention is made | formed in view of this situation, The objective is not including an alkali metal component and a magnesium component, and hold | maintains the sealing junction part of a metal member and a to-be-joined member airtightly also in a high temperature range. An object of the present invention is to provide a glass sealing material having high heat resistance and high heat resistance. Another object of the present invention is to provide a structure (for example, an oxygen ion conduction module) provided with a sealing joint using such a glass sealing material.

According to the present invention, crystallization in which at least one of BaO—Al ₂ O ₃ based crystal, BaO—ZnO—SiO ₂ based crystal, and BaO—Al ₂ O ₃ —SiO ₂ based crystal is precipitated in a glass matrix. A glass sealing material comprising glass is provided. The glass matrix does not contain alkali metal, Mg and Pb components, and when the entire glass matrix is 100 mol%, 95 mol% or more is a molar ratio in terms of oxide and the following composition: BaO 30 to 60 mol%; _{ZnO1~30mol%; SiO 2 1~30mol%;} Al 2 O 3 1~20mol%; B 2 O 3 10~30mol%; and a.

The glass sealing material disclosed herein has the following properties: (1) suitable high-temperature viscosity at the sealing bonding temperature; (2) relatively high thermal expansion coefficient; (3) heat resistance and durability at high temperatures; Is provided. Furthermore, the above-mentioned malfunction is prevented beforehand by not containing an alkali metal and Mg component. As a result, a member having a high thermal expansion coefficient (for example, a metal member) and the member to be joined can be sealed and joined in a highly airtight manner. Moreover, even in an environment exposed to a high temperature range, the high airtightness can be maintained over a long period of time.
In addition, in this specification, “BaO—Al ₂ O ₃ -based crystal” means that, in addition to crystals composed of a BaO component and an Al ₂ O ₃ component, for example, inevitable impurities other components are mixed in in minute amounts. Indicates that it can be tolerated. The same applies to BaO—ZnO—SiO ₂ based crystals and BaO—Al ₂ O ₃ —SiO ₂ based crystals.

In a preferred embodiment disclosed herein, the thermal expansion coefficient of the glass sealing material from 30 ° C. to 500 ° C. is 8 × 10 ⁻⁶ K ^{−1 to} 12 × 10 ⁻⁶ K ⁻¹ . Thereby, the consistency of the thermal expansion coefficient with a member having a high thermal expansion coefficient (for example, a metal member) can be stably improved, and the occurrence of defects such as cracks at the sealing joint is highly prevented. Can do.
In the present specification, “thermal expansion coefficient” is an average expansion coefficient (average linear expansion coefficient) measured using a thermomechanical analysis (TMA) in a temperature range from 30 ° C. to 500 ° C. The value obtained by dividing the amount of change in the sample length relative to the initial length of the sample by the temperature difference. The measurement of the thermal expansion coefficient can be performed according to JIS R 3102 (1995).

In a preferred embodiment disclosed herein, the viscosity (high temperature viscosity) log η at 850 ° C. is 3.5 Pa · s to 8.5 Pa · s. Thereby, at the time of sealing and joining the metal member and the member to be joined (at the time of glass melting), the glass sealing material can be provided with appropriate fluidity, and can be provided at a relatively low temperature (for example, 700 ° C to 900 ° C). ), The metal member and the member to be bonded can be sealed and bonded stably and highly confidentially. Moreover, even when exposed to a high temperature range, the shape of the sealing joint can be stably maintained, and more excellent heat resistance and durability can be realized.
In the present specification, “viscosity at 850 ° C.” refers to a viscosity log η calculated based on the Gent equation from the deformation rate measured using a glass parallel plate viscosity measuring apparatus.

In a preferred embodiment disclosed herein, the difference in thermal expansion coefficient before and after the thermal exposure when exposed to heat at 800 ° C. for 100 hours in an air atmosphere is ± 1.0 × 10 ⁻⁶ K ^−1. It is as follows. In other words, even when exposed to a high temperature range of 800 ° C., the change in thermal expansion coefficient is small. Therefore, it is possible to realize a sealed joint having excellent high-temperature durability that can maintain high airtightness over a long period of time.

In a preferred embodiment disclosed herein, the glass matrix further contains at least one of CaO and SrO in a molar ratio of less than 5 mol% in terms of oxide.
Thereby, the physical stability of the junction part in a high temperature range can be improved more, and the effect of this invention can be exhibited stably at a still higher level.

The glass sealing material disclosed here can seal-join a member (for example, metal member) with a high thermal expansion coefficient and a member to be joined in a highly airtight manner. Moreover, even when exposed to a high temperature region, the high airtightness can be maintained over a long period of time. Therefore, taking advantage of this feature, it can be suitably used in an oxygen ion conduction module. In other words, as another aspect disclosed herein, there is provided an oxygen ion conduction module provided with a sealed joint formed by firing the glass sealing material.
As a specific example, a solid oxide fuel cell (SOFC) including a solid electrolyte made of a ceramic having oxide ion conductivity, a metal member, the solid oxide fuel cell, and the metal A solid oxide fuel cell system including a sealing joint that seals and joins a member. Such a sealing joint is configured by firing the above-described glass sealing material.

It is a disassembled perspective view which shows typically one form of SOFC system provided with SOFC (single cell) and the metal interconnector joined to this single cell.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than the matters specifically mentioned in the present specification and necessary for carrying out the present invention (for example, a method for forming a joining member that does not characterize the present invention, a general manufacturing process of SOFC, etc.) ) Can be understood as a design matter of those skilled in the art based on the prior art in the field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

≪Glass sealing material≫
The glass sealing material disclosed here has, as an essential component, a BaO—Al ₂ O ₃ crystal, a BaO—ZnO—SiO ₂ crystal, and a BaO—Al ₂ O ₃ —SiO ₂ crystal in a glass matrix. It includes crystallized glass on which at least one of the crystals has been deposited. Typically, when the entire glass sealing material is 100% by mass, the crystallized glass component accounts for 50% by mass or more.
The crystal generally has a relatively high coefficient of thermal expansion of 9 × 10 ⁻⁶ K ⁻¹ or more. For example, BaAl ₂ O ₄ as a BaO—Al ₂ O ₃ based crystal has a thermal expansion coefficient (9.6 × 10 ⁻⁶ K ⁻¹ ) comparable to that of a metal. For this reason, it is effective for adjusting the thermal expansion coefficient to a relatively high value. Further, from the viewpoint of stably realizing a high thermal expansion coefficient, crystals having a low thermal expansion coefficient (for example, BaO—B ₂ O ₃ -based crystals, specifically BaB ₂ O ₄ etc.) are precipitated in the glass matrix. Preferably not.

  The amount of crystals deposited is not particularly limited. For example, when the total of the glass matrix component and the crystal component is 100% by mass, it is about 10% by mass (for example, 30% by mass or more) and 90% by mass. Or less (for example, 80% by mass or less). As a result, the effects of the present invention can be achieved more stably. The crystal precipitation amount can be measured by, for example, an internal standard method in powder X-ray crystal diffraction (XRD). Further, the amount of crystal precipitation can be adjusted, for example, by the composition ratio of the glass matrix described later and the conditions during crystallization treatment.

The glass matrix (glass composition) constituting the crystallized glass includes an alkali metal (for example, Li, Na, K, Rb, Cs, Fr. In particular, Li, Na, K.) component and a magnesium (Mg) component. And the lead (Pb) component, typically further does not contain an arsenic (As) component, and 95 mol% or more of the entire glass matrix has the following composition in the molar ratio in terms of oxide:
BaO 30-60 mol%;
ZnO 1-30 mol%;
SiO ₂ 1 to 30 mol% (e.g. 10 to 30 mol%);
Al ₂ O ₃ 1~20mol% (e.g. 10 to 20%);
B ₂ O ₃ 10~30mol% (e.g. 10 to 25 mol%);
It is composed of

Of the above-described constituent components, the barium component (barium oxide (BaO)) is a component for adjusting the thermal expansion coefficient of the glass sealing material and improving the thermal stability. It is also a constituent of BaO—Al ₂ O ₃ -based crystals, BaO—ZnO—SiO ₂ -based crystals, and BaO—Al ₂ O ₃ —SiO ₂ -based crystals precipitated in the glass matrix.
The proportion of BaO in the entire glass matrix is 30 mol% or more (for example, 33 mol% or more) in terms of oxide, and is 60 mol% or less (typically 55 mol% or less, for example, 52 mol% or less). Good. Thereby, the thermal expansion coefficient of the glass sealing material can be effectively increased. Furthermore, a suitable amount of the crystal can be precipitated in the glass matrix, and higher heat resistance and high temperature durability can be realized.

A zinc component (zinc oxide (ZnO)) is a component for adjusting the high temperature viscosity of the glass sealing material and improving the airtightness and stability (shape maintaining property) of the sealing joint. It is also a constituent component of BaO—ZnO—SiO ₂ -based crystals deposited in the glass matrix. Furthermore, the effect of suppressing the precipitation of SiO ₂ crystals (cristobalite crystals) is also a high component.
The proportion of ZnO in the entire glass matrix is preferably 1 mol% or more (for example, 4 mol% or more) and 30 mol% or less (for example, 28 mol% or less) in terms of a molar ratio in terms of oxide. Thereby, the high temperature viscosity of a glass sealing material can be adjusted to a suitable range. As a result, at the time of sealing joining (at the time of glass melting), the glass sealing material can be given appropriate fluidity. Moreover, even when exposed to a high temperature range, the shape of the sealing joint can be stably maintained. Furthermore, suitable types and amounts of crystals can be deposited in the glass matrix, and high heat resistance and high temperature durability can be imparted to the sealed joint. In addition, at least one of water resistance, thermal shock resistance, and durability of the sealed joint portion can be improved.

The silicon component (silicon oxide (SiO ₂ )) is a component (glass network former) constituting the skeleton of glass. Further, it is also a constituent component of a BaO—ZnO—SiO ₂ crystal or a BaO—Al ₂ O ₃ —SiO ₂ crystal.
The proportion of SiO _{2 in} the entire glass matrix is 1 mol% or more (for example, 2 mol% or more, preferably 10 mol% or more, more preferably 15 mol% or more) in terms of oxide, and 30 mol% or less (typically Specifically, it is preferably 25 mol% or less, for example, 20 mol% or less. Thereby, the high temperature viscosity of a glass sealing material can be adjusted to a suitable range. Further, a suitable amount of crystals can be precipitated in the glass matrix, and higher heat resistance and high temperature durability can be realized. Furthermore, at least one of water resistance, chemical resistance, and thermal shock resistance of the sealing joint can be improved. In particular, by setting the ratio of SiO ₂ to 10 mol% or more in terms of oxide, the shape of the sealed joint can be more stably maintained even when exposed to a high temperature range. .

The aluminum component (aluminum oxide (Al ₂ O ₃ )) is a component for improving the adhesion stability by controlling the fluidity during glass melting. It is also a constituent of BaO—Al ₂ O ₃ -based crystals and BaO—Al ₂ O ₃ —SiO ₂ -based crystals precipitated in the glass matrix.
The ratio of Al ₂ O ₃ occupying the entire glass matrix is 1 mol% or more (for example, 10 mol% or more) and preferably 20 mol% or less (for example, 18 mol% or less) as a molar ratio in terms of oxide. Thereby, a metal member and a member to be joined can be sealed and joined more stably (homogeneously). Further, a suitable amount of crystals can be precipitated in the glass matrix, and higher heat resistance and high temperature durability can be realized. Furthermore, the chemical resistance of the sealing joint can be improved.

The boron component (boron oxide (B ₂ O ₃ )) is a component that improves the fluidity at the time of melting the glass (lowers the softening point of the glass frit). It is also a component for adjusting the thermal expansion coefficient of the glass sealing material.
The ratio of B ₂ O _{3 in} the entire glass matrix is 10 mol% or more and 30 mol% or less (typically 25 mol% or less, for example, 20 mol% or less) in terms of a molar ratio in terms of oxide. Thereby, the thermal expansion coefficient of the glass sealing material can be adjusted to a relatively high value. Moreover, the high temperature viscosity of a glass sealing material can be adjusted to a suitable range.

The glass matrix may be composed of the five main components described above, or any other component than the above is less than 5 mol% (typically, as long as the effects of the present invention are not significantly impaired). 4 mol% or less, for example, 2 mol% or less). Examples of such additional components include oxides such as CaO, SrO, Bi ₂ O ₃ , TiO ₂ , ZrO ₂ , V ₂ O ₅ , Nb ₂ O ₅ , FeO, Fe ₂ O ₃ , and Fe _3. Examples include O ₄ , CuO, Cu ₂ O, SnO, SnO ₂ , P ₂ O ₅ , La ₂ O ₃ , CeO _{2 and the} like.

In a preferred embodiment, the glass matrix contains at least one of CaO and SrO in a ratio of less than 5 mol% in terms of a molar ratio in terms of oxide. Thereby, the thermal stability of the glass sealing material can be further improved. Furthermore, when a calcium component (CaO) is included, there is also an effect of increasing the hardness of the sealing joint and improving the wear resistance.
The proportion of CaO and / or SrO in the entire glass matrix is less than 5 mol% in terms of oxide, for example 1 mol% or more and less than 5 mol%, preferably 2 mol% or more and less than 5 mol%.

  In another preferred embodiment, the glass matrix is composed of a multi-component system having 6 or more components (for example, 6 to 10 components). By including 6 or more components, the physical stability of the sealing joint is further improved. From the viewpoint of workability and cost, the glass matrix is preferably composed of 10 components or less.

  In addition, the glass matrix which comprises crystallized glass does not contain an alkali metal component, a magnesium component, and a lead component. Typically, it also does not contain an arsenic component. In other words, these components are not actively added to the glass matrix disclosed herein (it is allowed to be mixed as an inevitable impurity). As described above, alkali metal components (for example, potassium component and sodium component) are likely to diffuse (scatter) into the metal member in a high temperature environment, thereby changing the thermal expansion coefficient of the sealing joint or mechanical strength. It may be reduced. Moreover, when it contains a magnesium component, it is difficult to adjust to a suitable high temperature viscosity, for example, the joining temperature (temperature at the time of glass melting) may increase, or the shape maintainability may decrease in a high temperature range. . By not containing an alkali metal component and a magnesium component, the above-described problems can be prevented in advance. Furthermore, since an arsenic component and a lead component have a bad influence with respect to a human body and an environment, it is unpreferable from a viewpoint of environmental property, workability | operativity, and safety.

The crystallized glass disclosed herein has the following properties: (1) Viscosity log η at 850 ° C. is 3.5 Pa · s to 8.5 Pa · s (for example, 4.2 Pa · s to 6.7 Pa · s). (2) The coefficient of thermal expansion from 30 ° C. to 500 ° C. is 8 × 10 ⁻⁶ K ^{−1 to} 12 × 10 ⁻⁶ K ⁻¹ (for example, 9 × 10 ⁻⁶ K ^{−1 to} 10.5 × 10 ^−6). K ^-1) is; (3) 800 the difference in thermal expansion coefficients of the front and rear the heat exposure time of performing the thermal exposure of 100 hours at ℃ is ± 1.0 × ¹⁰ -6 ^{K -1} or less at the atmosphere At least one (preferably all). Thereby, the effect of the present invention can be stably exhibited at a higher level.

  In addition to the crystallized glass, the glass sealing material can appropriately contain various components known to be added to this type of glass sealing material. Examples of such additive components include organic binders and organic solvents. As the organic binder, various binders usually used in this kind of glass paste can be considered. For example, cellulose polymers such as methyl cellulose, ethyl cellulose, and nitro cellulose, acrylic resins, epoxy resins, amine resins, and the like can be exemplified. The same applies to the organic solvent, and various organic solvents usually used in this type of glass paste can be considered. For example, terpineol, ether solvents, ester solvents, various glycols and the like can be exemplified.

That is, the form of the glass sealing material disclosed here is not particularly limited, and can be arbitrarily adjusted according to the application. For example, it can take forms such as a cullet shape, a powder shape, a frit shape, a pellet shape, a plate shape, and a paste shape.
As an example, the paste-like glass sealing material can be applied to a member to be bonded (metal member or the like) by a technique such as coating or printing by adjusting to an appropriate viscosity. Therefore, a paste-like glass sealing material can be preferably used when performing sealing bonding between members having complicated shapes or sealing bonding in a complicated form. Thereby, sealing joining can be performed more simply.

≪Glass sealing material manufacturing method≫
Although the manufacturing method of such a glass sealing material is not particularly limited, for example, first, Ba, Zn, Si, Al, and B are substantially constituent components (for example, the above five components are oxide-converted molar ratios). The glass raw material powder occupying 95 mol% or more); next, the glass raw material powder is melted and then rapidly cooled to prepare a glass matrix (glassy intermediate); By crystallizing the matrix, at least one of a BaO—Al ₂ O ₃ crystal, a BaO—ZnO—SiO ₂ crystal, and a BaO—Al ₂ O ₃ —SiO ₂ crystal in the glass matrix. By precipitating one. Hereinafter, each step will be described in detail.

  In the preparation of the glass raw material powder, for example, industrial products, reagents, or various mineral raw materials including oxides, carbonates, nitrates, complex oxides, and the like containing the respective constituents described above are prepared, and these are desired. Mix so that the composition becomes. The raw material powder can be prepared, for example, by putting the raw material into a mixer such as a ball mill and mixing for several hours to several tens of hours.

  Next, after drying the obtained glass raw material powder, it is heated and melted under conditions of high temperature (typically 1000 ° C. to 1500 ° C.) to prepare glass (glassy intermediate) by cooling or quenching. can do. In a preferred embodiment, the obtained glass (glassy intermediate) is pulverized to an appropriate size (particle size) to produce glass (glassy intermediate) powder. The average particle diameter of the glassy intermediate is preferably, for example, 0.5 μm to 50 μm (typically 1 μm to 10 μm).

  Next, the glassy intermediate prepared above is crystallized (heat treatment). Thereby, the said crystal | crystallization can be deposited in a glass matrix and crystallized glass can be obtained. In the crystallization treatment, the glassy intermediate is allowed to stand for a predetermined time (typically 10 minutes or more, for example, 10 ° C., for example) in a temperature range where crystallization can be induced (for example, 800 ° C. to 1200 ° C., preferably 800 ° C. to 1000 ° C.). Minutes to 60 minutes). In a preferred embodiment, the obtained crystallized glass is prepared into a form such as a cullet or powder by pulverization or sieving (classification). As a result, it is possible to realize a sealed joint with higher airtightness and high quality. The average particle diameter of the crystallized glass may be, for example, about 0.1 μm to 10 μm, although it depends on the application.

  The obtained crystallized glass (pulverized cullet or powder) can be appropriately processed into a form suitable for the application. For example, after compression molding into an arbitrary shape, it can be calcined to such an extent that the glass particles are bonded to each other to form a pellet. Or you may mix with an organic binder, an organic solvent, etc., and may prepare in paste form. There are no particular restrictions on the paste dispersion and mixing method, and it can be carried out in the same manner as before.

≪Join method≫
The glass sealing material prepared as described above is characterized by a relatively high thermal expansion coefficient. For this reason, it can be widely used for joining members having a high thermal expansion coefficient, for example, joining between metal members (between similar members), joining between a metal member and a ceramic member (between different members), and the like.
In one specific embodiment of the bonding method, first, a glass sealing material is prepared in a desired form. Next, one metal member and a member to be joined are prepared. Next, it arrange | positions so that these members may mutually contact and connect, and the glass sealing materials, such as the said pellet form or a paste form, are provided (arrangement or application | coating) to the said connection part. And after drying this composite_body | complex, it bakes by the temperature range (typically 600 degreeC or more, for example, 700 to 900 degreeC) more than the softening point of this glass sealing material. According to the glass sealing material disclosed here, various members can be hermetically sealed and joined.

As an example of the metal member, one made of a metal material such as stainless steel, aluminum, chromium, iron, nickel, copper, silver, manganese, and alloys thereof can be considered. More specifically, ferritic or austenitic stainless steel, pure aluminum, aluminum alloys (duralumin, aluminum bronze, etc.), silver, silver alloys (Western silver, etc.), copper, copper alloys (phosphor bronze, etc.), etc. are exemplified. The The thermal expansion coefficient of these metal members is exemplified by the fact that the thermal expansion coefficient from 30 ° C. to 500 ° C. is about 10 × 10 ⁻⁶ K ⁻¹ to 15 × 10 ⁻⁶ K ⁻¹ as an approximate guide. .

Moreover, although it does not restrict | limit especially as a to-be-joined member, For example, the said metal member and a ceramic member are illustrated. As an example of the ceramic member, one made of a ceramic material such as alumina, forsterite, titania, yttria, zirconia, or partially stabilized zirconia can be considered. These may be a single element of any one kind of ceramic material, or are composed of a ceramic composite material (for example, mullite, steatite, alumina zirconia, etc.) in which two or more kinds of ceramic materials exemplified above are combined. It may be a thing. Among these, fine ceramic materials such as alumina having various excellent properties mechanically, thermally, electrically, magnetically, and chemically can be preferably used. The thermal expansion coefficient of these ceramic members is, as an approximate guide, the thermal expansion coefficient from 30 ° C. to 500 ° C. is about 6 × 10 ⁻⁶ K ⁻¹ to 8 × 10 ⁻⁶ K ^−1. .

≪Structure≫
In other words, according to the technology disclosed herein, a metal member, a member to be joined, and a sealing joint that seal-joins the metal member and the member to be joined are provided, and the sealing joint is described above. A structure obtained by firing the glass sealing material is provided. According to the glass sealing material disclosed here, a metal member having a high thermal expansion coefficient and a member to be bonded can be sealed and bonded in a highly airtight manner. Moreover, even when exposed to a high temperature region, the high airtightness can be maintained over a long period of time. That is, superior heat resistance and durability can be realized as compared with the case where a conventional glass sealing material is used.
Taking advantage of the above-described features, the glass sealing material disclosed herein can be suitably used, for example, in an oxygen ion conduction module. In other words, as another aspect disclosed herein, there is provided an oxygen ion conduction module provided with a sealed joint formed by firing the glass sealing material.

≪Solid oxide fuel cell (SOFC) system≫
As a preferred example of the oxygen ion conduction module, a solid oxide fuel cell (SOFC) system will be described as an example. Such an SOFC system includes at least a solid oxide fuel cell (single cell) and a metal member. And the sealing joining part formed by baking the glass sealing material disclosed here is formed between this single cell and the metal member. By using the glass sealing material as described above, for example, sealed bonding that can keep a metal member and a single cell hermetically sealed for a long time even when exposed to a high temperature range of about 600 ° C. to 900 ° C. Part can be realized. Therefore, a high-performance SOFC system with excellent heat resistance can be realized.

A single cell is constructed by forming a porous structure of an air electrode (cathode) on one side of a dense solid electrolyte made of an oxide ion conductor and a porous structure of a fuel electrode (anode) on the other side. Yes. Examples of the solid electrolyte include those made of yttria stabilized zirconia (YSZ) and gadolinia doped ceria (GDC). Examples of the air electrode include lanthanum cobaltate (LaCoO ₃ ) and lanthanum manganate (LaMnO ₃ ) perovskite oxides. Examples of the fuel electrode include those made of cermet of nickel (Ni) and YSZ.
The metal member may be a gas pipe for supplying a gas (for example, an oxygen-containing gas, typically air) to a single cell, or the unit for electrically connecting SOFC single cells to form a stack. Examples include an interconnector disposed between cells. Such metal members may be the same as those employed in conventional SOFC systems. Specifically, what consists of metal materials, such as aluminum, chromium, iron, nickel, copper, stainless steel, is illustrated.
The manufacturing method of the SOFC system may be in accordance with a conventionally known manufacturing method and does not require special processing, and thus detailed description is omitted.

  Hereinafter, a preferred embodiment of the present invention will be described with reference to FIG. In the following drawings, members / parts having the same action are described with the same reference numerals, and overlapping descriptions may be omitted or simplified. Further, the dimensional relationship (length, width, thickness, etc.) in each drawing does not necessarily reflect the actual dimensional relationship.

FIG. 1 is an exploded perspective view schematically showing one form of an SOFC system including an SOFC (single cell) and a metal interconnector joined to the single cell. The SOFC system 30 is configured as a stack in which SOFCs (single cells) 10 </ b> A and 10 </ b> B are stacked through a metal interconnector 20. The unit cells 10A and 10B have a sandwich structure in which both surfaces of a layered solid electrolyte 14 are sandwiched between a layered fuel electrode (anode) 12 and an air electrode (cathode) 16, respectively. The interconnector 20A disposed in the center of the drawing is sandwiched between two single cells 10A and 10B, one cell facing surface 22 faces (adjacent) the air electrode 16 of the cell 10A, and the other cell. The facing surface 26 faces (adjacent) the fuel electrode 12 of the cell 10B. The glass sealing material disclosed herein is applied between the cell facing surfaces 22 and 26 of the interconnector 20A and the facing surfaces of the corresponding fuel cell 12 or air electrode 16 on the corresponding single cell 10A or 10B side. A sealing joint (not shown) is formed. In addition, a plurality of grooves are formed in the cell facing surface 22 to constitute an air flow path 24 through which the supplied oxygen-containing gas (typically air) flows. Similarly, a plurality of grooves are also formed in the opposite cell facing surface 26 to constitute a fuel gas flow path 28 through which the supplied fuel gas (typically H ₂ gas) flows. In the interconnector 20 having such a configuration, the air flow path 24 and the fuel gas flow path 28 are typically formed so as to be orthogonal to each other.

  Hereinafter, some test examples relating to the present invention will be described, but the present invention is not intended to be limited to those shown in the test examples.

In this test, a total of 10 types of glass sealing material samples with different glass raw material compositions and heat treatment (crystallization treatment) conditions were produced. Specifically, first, glass raw material powder having the composition shown in Table 1 was melted at 1100 ° C. to 1300 ° C. and then rapidly cooled. Next, this was pulverized, and the crystallization treatment was performed on the samples whose crystallization treatment conditions are listed in Table 1. In addition, heat treatment was not performed on the samples having “-” in the column of crystallization treatment in Table 1. And about the sample which performed the crystallization process, it grind | pulverized again after the said crystallization process. In this way, 10 types of glass frit (S1 to 8) were produced.
As a comparative example, a commercially available heat-resistant glass (manufactured by Asahi Glass Co., Ltd.) having the composition shown in Table 1 was prepared.

[Evaluation of thermal expansion coefficient]
The produced glass frit (S1-8) and commercially available heat-resistant glass were each press-formed into 50 mm × 7 mm × 7 mm rods and calcined at 700 ° C. for 10 minutes. After calcination, the specimen was cut into a cylindrical shape having a diameter of about 5 mm × 10 to 20 mm with a diamond cutter to obtain a test specimen for measurement. This test piece was evaluated using a thermomechanical analyzer (manufactured by Rigaku Corporation, TMA8310). Specifically, the thermal expansion coefficient was calculated from the average linear expansion amount between 30 ° C. and 500 ° C. when the temperature was increased from room temperature (25 ° C.) to 1000 ° C. at a constant rate of 10 ° C./min. The results are shown in the corresponding column of Table 2.
As shown in Table 2, Sample 1 had a low thermal expansion coefficient of 6.1 × 10 ⁻⁶ K ⁻¹ . Others had a relatively high thermal expansion coefficient of 8 × 10 ⁻⁶ K ⁻¹ or more.

[Evaluation of crystalline phase in glass]
About the produced glass frit (S1-8) and commercially available glass for heat resistance, the powder X-ray crystal diffraction (XRD) was performed, respectively, and the presence or absence of crystal precipitation was confirmed. The results are shown in the corresponding column of Table 2. In Table 2, the crystal phase is shown when crystal precipitation is confirmed, and “-” is shown when crystal precipitation is not confirmed.
As shown in Table 2, no crystal phase was observed in Sample 1 and Sample 4-1, and commercially available heat-resistant glass. In other samples, some crystal phase precipitation was observed.

[Evaluation of high temperature viscosity]
The produced glass frit (S1-8) and a commercially available heat-resistant glass were each press-formed into a cylindrical shape having a diameter of about 7 to 10 mm and a height of about 5 to 7 mm, and calcined at 700 ° C. for 10 minutes. After calcining, the prepared measurement sample was sandwiched between alumina plates, and the viscosity log η at 850 ° C. was determined. Specifically, the deformation amount in the height direction from room temperature (25 ° C.) to 850 ° C. was detected using a glass parallel plate viscometer. The viscosity log η at 850 ° C. was calculated from the deformation rate of the measurement sample based on the Gent equation.
Gent formula: η = 2πMgH ⁵ / 3V (−dH / dt) (2πH ³ + V)
(However, η: viscosity (Poise), M: load (g), H: height of sample (cm), g: acceleration of gravity (cm / s ² ), V: sample volume (cm ³ ), dH / dt : Sample deformation speed (cm / s).)
As shown in Table 2, the viscosity log η of Samples 1 to 8 was in the range of 2.9 to 8.9 Pa · s.

[Evaluation of bondability with SUS substrate]
The produced glass frit (S1 to 8) and a commercially available heat-resistant glass were each press-formed into a disk shape of Φ15 mm × 2.5 mm to produce pellets. This pellet is placed on a substrate made of ferritic stainless steel (SUS430, coefficient of thermal expansion: 10 × 10 ⁻⁶ K ^{−1 to} 13 × 10 ⁻⁶ K ⁻¹ ) and fired at 850 ° C. for 30 minutes in the air. Thus, the pellet and the substrate were joined. Then, the penetration inspection was performed about each laminated body, and the presence or absence of the crack was confirmed. The results are shown in the corresponding column of Table 2. In Table 2, “◯” indicates that no crack was confirmed, and “x” indicates that a crack was observed at the joint.
As shown in Table 2, cracks were observed in samples 1 and 8, but the pellets and the substrate were well bonded in the other samples. In sample 2, wetting and spreading were remarkable, and it was difficult to maintain the joint. In Sample 6, the glass spread slightly after firing.

[Diffusion evaluation to metal]
About the laminated body produced by the said bondability evaluation, it was confirmed whether the glass component was diffusing on the said board | substrate (SUS430). Specifically, the laminate is observed from above using a scanning electron microscope (SEM), and an observation image obtained by energy dispersive X-ray spectroscopy (EDX) analysis is made of glass. The presence of glass components on the substrate surface was confirmed by mapping with component elements of the matrix. The results are shown in the corresponding column of Table 2. In Table 2, “◯” indicates that the glass component was not observed, “×” indicates that the glass component was observed, and “−” indicates that the glass component was not measured.
As shown in Table 2, in the commercially available heat-resistant glass containing an alkali metal and an Mg component in the glass matrix, diffusion of the glass component (alkali metal element) was observed on the substrate. On the other hand, in samples 1 to 7, no diffusion of glass components was observed on the substrate.

[Evaluation of heat resistance]
The prepared glass frit (S1 to 8) and a commercially available heat-resistant glass were exposed to heat at 800 ° C. for 100 hours in an air atmosphere to evaluate heat resistance. Specifically, first, the thermal expansion coefficient after heat exposure was measured in the same manner as described above. And the variation | change_quantity from the thermal expansion coefficient before heat exposure was calculated | required. The results are shown in the corresponding column of Table 2. In Table 2, “◯” indicates that the change in thermal expansion coefficient was ± 1.0 × 10 ⁻⁶ K ⁻¹ or less, and “×” indicates that the change in thermal expansion coefficient was greater than that. “-” Indicates that measurement has not been performed.
As shown in Table 2, Samples 3,4-2,5,6,7-2 had a small change in thermal expansion coefficient before and after thermal exposure and high heat resistance.

  In the column of comprehensive evaluation in Table 2, “x” is marked when there is “x” in any of the above evaluation items. In addition, although there is no item of “x”, “△” is marked when there is a special remark item as shown in the other column. When all the evaluation items are good, “◯” is marked.

From the above results, a crystal in which at least one of a BaO—Al ₂ O ₃ crystal, a BaO—ZnO—SiO ₂ crystal, and a BaO—Al ₂ O ₃ —SiO ₂ crystal is precipitated in the glass matrix. A glass sealing material containing a vitrified glass, wherein when the entire glass matrix is 100 mol%, 95 mol% or more is a molar ratio in terms of oxides: BaO 30 to 60 mol%; ZnO 1 to 30 mol%; SiO ₂ 1 to 30 mol% (particularly _{SiO 2 10~30mol%); Al 2} O 3 1~20mol%; B 2 O 3 10~30mol%; by using a glass sealing material which is composed of an alkali metal Even without Mg, Pb and As components, there is no crack with metal member (ferritic stainless steel) and high airtightness It was found to be formed a sealing joint.

It was also found that the glass sealing material preferably has the following properties.
(1) Viscosity log η at 850 ° C. is 3.5 Pa · s to 8.5 Pa · s.
(2) The thermal expansion coefficient from 30 ° C. to 500 ° C. is 8 × 10 ⁻⁶ K ^{−1 to} 12 × 10 ⁻⁶ K ⁻¹ .
(3) The difference in thermal expansion coefficient before and after the heat exposure when the heat exposure is performed at 800 ° C. for 100 hours in the air atmosphere is ± 1.0 × 10 ⁻⁶ K ⁻¹ or less.

  As mentioned above, although the specific example of this invention was demonstrated in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

10A, 10B SOFC (single cell)
12 Fuel electrode (anode)
14 Solid electrolyte layer 16 Air electrode (cathode)
20, 20A Interconnector 30 Solid oxide fuel cell system (SOFC system)

Claims (7)

In the glass matrix, at least one of (1) BaO—Al ₂ O ₃ based crystal, (2) BaO—ZnO—SiO ₂ based crystal, and (3) BaO—Al ₂ O ₃ —SiO ₂ based crystal. (However, the (1) BaO—Al ₂ O ₃ -based crystal is essential) is a glass sealing material containing crystallized glass on which is deposited,
The glass matrix does not contain alkali metal, Mg and Pb components, and when the entire glass matrix is 100 mol%, 95 mol% or more is the following composition in molar ratio in terms of oxide:
BaO 30-60 mol%;
ZnO 1-30 mol%;
SiO ₂ 1~30mol%;
Al ₂ O ₃ 1~20mol%;
B ₂ O ₃ 10~30mol%;
The glass sealing material comprised from these. Thermal expansion coefficient of from 30 ° C. to 500 ° C. is ^{8 × 10 -6 K -1 ~12 ×} 10 -6 K -1, the glass sealing material of claim 1. The glass sealing material according to claim 1, wherein a viscosity log η at 850 ° C. is 3.5 Pa · s to 8.5 Pa · s. Any of Claims 1-3 whose difference of the thermal expansion coefficient before and behind the said heat exposure at the time of performing heat exposure for 800 hours and 800 degreeC in air | atmosphere atmosphere is less than +/- 1.0 * 10 <^-6> K < ^-1 >. The glass sealing material of crab.   The glass sealing material in any one of Claims 1-4 in which the said glass matrix contains at least 1 sort (s) of CaO and SrO in the ratio below 5 mol% further by the molar ratio of oxide conversion. Al ₂ O ₃ The glass sealing material in any one of Claims 1-5 whose is 10 mol% or more. A solid oxide fuel cell including a member made of ceramic having oxide ion conductivity;
A metal member;
A sealing joint for sealingly joining the solid oxide fuel cell and the metal member;
A solid oxide fuel cell system comprising:
The sealing joint formed by firing a glass sealing material according to any one of claims 1 to 6 solid oxide fuel cell system.

Images