Method for producing assembly, and assembly

Abstract

To realize a glass joint part excellent in collapse resistance in a high temperature environment.SOLUTION: A production method disclosed herein includes: an application process of applying a joint material including a glass powder to a joint part contacted with a plurality of inorganic components; and a calcination process of calcining the joint material at a calcination temperature of a temperature higher than a melt temperature of the glass powder. The glass powder substantially comprises 14 to 22 mol% of SiO2, 2 to 4 mol% of Al2O3, 12 to 22 mol% of B2O3, 51 to 60 mol% of RO (oxide of a group II element) and 5.5 to 7 mol% of ZnO. The production method further includes a preliminary heating process of heating the joint material at a preliminarily heating temperature of a crystallization temperature of the glass powder or higher and a melt temperature or lower before the calcination process. A glass joint part excellent in collapse resistance in a high temperature environment can be realized since an oxide crystal excellent in heat resistance is generated thereby in the glass joint part.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The technology disclosed herein relates to an assembly in which a plurality of inorganic components are bonded via a glass bonding portion, and a method for manufacturing the assembly. [Background technology]

[0002] Inorganic components such as metal and ceramic components are sometimes joined via glass joints (glass joints). For example, electrochemical cells such as SOECs and SOFCs are used in the form of electrochemical stacks, in which multiple components are joined to the cell. Specifically, in electrochemical stacks, the connection between the cell electrodes (fuel electrodes, air electrodes, etc.) and gas pipes is joined via dense glass joints. Glass joints are also formed between solid electrolyte layers and metal components (gas pipes, metal plates, etc.) and between multiple metal components. This prevents gas leakage from the joints between multiple inorganic components, which could lead to performance degradation. In this specification, a structure in which multiple inorganic components are joined via glass joints, such as this electrochemical stack, is referred to as an "assembly."

[0003] Glass joints are formed by firing a joining material containing glass powder. For example, Japanese Patent Application Laid-Open No. 2020-167093 discloses a sealing green sheet containing glass powder. Furthermore, Japanese Patent Application Laid-Open No. 2020-164377 discloses a paste containing glass powder. In these prior arts, a firing process is carried out after a joining material is applied (sticked or coated) to the joining portion between inorganic components. This melts the glass powder in the joining material and adheres to the joining object. Then, after the firing process, the molten glass solidifies, forming a joint at the connection portion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2020-167093 [Patent Document 2] Patent Publication No. 2020-164377 Summary of the Invention [Problem to be solved by the invention]

[0005] However, some assemblies are exposed to high-temperature environments again after the firing process to form the glass joint. For example, electrochemical stacks can reach temperatures of 750°C or higher during use. Furthermore, in the manufacture of electrochemical stacks, heat treatment of other components may be performed after the glass joint is formed. In this case, the glass joint may soften slightly due to exposure to a high-temperature environment. If external stress is applied to the softening glass joint, significant deformation (crushing) may occur.

[0006] The technology disclosed herein solves this problem and provides a technology for realizing a glass joint that has excellent crush resistance in a high-temperature environment. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, a method for manufacturing an assembly having the following configuration is provided.

[0008] The manufacturing method disclosed herein is a method for manufacturing an assembly in which multiple inorganic components are joined via a glass joint. This manufacturing method includes a step of applying a joining material containing glass powder to a joint portion where multiple inorganic components are in contact with each other, and a step of firing the joining material at a firing temperature equal to or higher than the melting temperature of the glass powder to form a glass joint between the multiple inorganic components. The glass powder in the joining material used in the manufacturing method disclosed herein has the following composition in molar ratios calculated as oxides: SiO2 14~22mol%; Al2O3 2~4mol%; B2O3 12~22mol%; RO 51-60 mol%; ZnO 5.5 to 7 mol% (where RO is an oxide of a Group 2 element.) Furthermore, in the manufacturing method disclosed herein, a preheating step is carried out before the firing step, in which the bonding material is heated at a preheating temperature that is equal to or higher than the crystallization temperature and equal to or lower than the melting temperature of the glass powder.

[0009] As a result of various experiments, the inventors discovered that the manufacturing method described above can form glass joints with significantly improved crush resistance in high-temperature environments. While not intending to limit the technology disclosed herein, it is believed that this improved crush resistance occurs through the following mechanism. First, in the manufacturing method disclosed herein, a preheating step is performed before the firing step in which the glass powder is melted. In this preheating step, the joining material is heated at a preheating temperature above the crystallization temperature but below the melting temperature. This produces a large amount of well-grown oxide crystals in the glass before melting. Furthermore, in the technology disclosed herein, borosilicate glass, which contains a large amount of oxides of Group 2 elements (RO) and has a B2O3 content limited to a certain level, is used as the glass powder in the joining material. The oxide crystals produced from the constituent elements of this borosilicate glass often have excellent heat resistance, such as BaMg2(SiO7) and CaB2O4. It is believed that the large amount of heat-resistant oxide crystals formed in the glass significantly improved the crush resistance of the glass joint after firing in a high-temperature environment.

[0010] According to another aspect of the present disclosure, there is provided an assembly in which a plurality of inorganic components are joined via a glass joint. The assembly includes a plurality of inorganic components that are in contact with each other at a joint portion, and a glass joint formed at the joint portion. The glass joint has the following composition in terms of oxide molar ratio: SiO2 14~22mol%; Al2O3 2~4mol%; B2O3 12~22mol%; RO 51-60 mol%; ZnO 5.5 to 7 mol% (where RO is an oxide of a Group 2 element.) and has a crystallinity of 30 or more as determined by X-ray diffraction.

[0011] The assembly having the above configuration is manufactured by the manufacturing method disclosed herein. As described above, a large amount of fully grown oxide crystals is generated inside the glass joint of this assembly. Therefore, the glass joint of the assembly disclosed herein has the characteristic of having a crystallinity of 30 or more as determined by X-ray diffraction. Furthermore, this glass joint has excellent crush resistance in high-temperature environments. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a flow chart illustrating one embodiment of a method for manufacturing an assembly disclosed herein. [Figure 2] FIG. 2 is a perspective view showing an example of the structure of an electrochemical stack. DETAILED DESCRIPTION OF THE INVENTION

[0013] Preferred embodiments of the technology disclosed herein are described below. It should be noted that matters other than those specifically mentioned in this specification that are necessary for implementing the technology disclosed herein (e.g., the type of assembly, detailed structure, etc.) can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and the common general technical knowledge in the relevant field. In the following description, "A to B (where A and B are any values)" includes the values ​​of A and B (upper and lower limits).

[0014] <Assembly manufacturing method> An embodiment of the manufacturing method disclosed herein will be described below: Figure 1 is a flowchart illustrating an embodiment of the manufacturing method of the assembly disclosed herein.

[0015] The manufacturing method according to this embodiment manufactures an assembly (e.g., an electrochemical stack) that is a structure in which multiple inorganic components are bonded via glass bonding parts. As shown in Fig. 1, this manufacturing method includes an application step S10, a preheating step S20, and a firing step S30. Each step will be described below.

[0016] 1. Applying step S10 In this process, a bonding material containing glass powder is applied to the joint where multiple inorganic parts are in contact. The term "inorganic parts" used here is not limited to parts made of a specific material, but rather broadly encompasses heat-resistant parts that can be bonded via a glass joint. Examples of inorganic parts include metal parts, ceramic parts, and carbon parts. An example of an inorganic part is an electrode and a pipe (such as a metal connection plate) of an electrochemical cell.

[0017] As described above, the manufacturing method according to this embodiment uses a bonding material containing glass powder. The bonding material is not limited to a specific form as long as it can form a glass bonding portion by melting the glass powder. For example, an example of the bonding material is a sheet-shaped molded body (sealing green sheet) containing glass powder. This sealing green sheet has the advantage of being easily applied to the connecting portion. Another example of the bonding material is a glass paste in which glass powder is dispersed in a dispersion medium. This glass paste has the advantage of being easily adjustable in the amount to be applied to the connecting portion.

[0018] As described above, the bonding material contains glass powder. The bonding material may also contain other optional components such as a resin material, a solvent, and an additive. The bonding material will be described below.

[0019] (1) Glass powder Glass powder is an essential component of the bonding material, which is the main component of the glass bonding portion. Specifically, in the manufacturing method disclosed herein, the glass powder is melted in a firing step S30, which will be described later. The melted glass then solidifies to form the glass bonding portion. Here, the glass powder in this embodiment is substantially composed of SiO2, Al2O3, B2O3, RO (an oxide of a Group 2 element), and ZnO. Here, "substantially composed" means that the total content ratio of SiO2, Al2O3, B2O3, RO, and ZnO is 90 mol% or more (preferably 92 mol% or more, more preferably 94 mol% or more, even more preferably 96 mol% or more, and particularly preferably 98 mol% or more). Note that the "content ratio" in this specification is expressed as mol% of oxide when the total moles of glass is 100 mol%.

[0020] Each component in the glass powder will be described below.

[0021] (1-1)SiO2 First, SiO2 is a component that constitutes the glass skeleton (glass matrix). Without a certain amount of SiO2, it is difficult to obtain a vitrified composite oxide. SiO2 also contributes to improving the durability (heat resistance, water resistance, chemical resistance, thermal shock resistance, etc.) of the glass joint. Therefore, the SiO2 content in the glass powder is set to 14 mol% or more. From the viewpoint of further improving the durability of the glass joint, the SiO2 content is preferably 14.2 mol% or more, more preferably 14.4 mol% or more, and particularly preferably 15 mol% or more. On the other hand, glass containing a large amount of SiO2 has a high melting temperature, making it difficult to melt it to a state with suitable fluidity. As a result, the bondability of the glass joint after firing may be reduced. From this viewpoint, the technology disclosed herein limits the SiO2 content to 22 mol% or less. From the viewpoint of further improving the bondability of the glass joint after firing, the upper limit of the SiO2 content is preferably 20 mol% or less, more preferably 19 mol% or less, even more preferably 18 mol% or less, and particularly preferably 17 mol% or less.

[0022] (1-2)Al2O3 Al2O3 is also a component constituting the glass skeleton. Because Al2O3 has the function of stabilizing the glass skeleton, it contributes to improving the durability (heat resistance, acid resistance, water resistance, etc.) of the glass joint after firing. For this reason, in the technology disclosed herein, the Al2O3 content in the glass particles is set to 2 mol% or more. From the viewpoint of further improving the durability of the glass joint, the Al2O3 content is preferably 2.2 mol% or more, more preferably 2.4 mol% or more, and particularly preferably 2.6 mol% or more. On the other hand, as with SiO2 described above, if the Al2O3 content is too high, the bondability of the glass joint may be reduced. From this viewpoint, in the technology disclosed herein, the Al2O3 content is limited to 4 mol% or less. From the viewpoint of further improving the bondability of the glass joint after firing, the upper limit of the Al2O3 content is preferably 3.8 mol% or less, more preferably 3.6 mol% or less, even more preferably 3.4 mol% or less, and particularly preferably 3.2 mol% or less.

[0023] (1-3)B2O3 Like SiO2, B2O3 is a component that can form the glass skeleton. The inclusion of B2O3 in part of the glass skeleton lowers the melting temperature, making it easier to melt the glass powder to a state with suitable fluidity. As a result, even when firing at low temperatures, the bondability to inorganic components can be improved. For this reason, the B2O3 content in the glass powder is set to 12 mol% or more. To further improve the bondability of the glass joint, the B2O3 content is preferably 13 mol% or more, more preferably 14 mol% or less, even more preferably 15 mol% or more, and particularly preferably 16 mol% or more. On the other hand, it has been confirmed that glass with an excessively high B2O3 content does not easily improve crush resistance in high-temperature environments, even when subjected to the preheating step S20 described below. This is thought to be due to the following phenomenon. As described above, B2O3 lowers the melting temperature of the glass powder. Therefore, glass powders containing a large amount of B2O3 have a crystallization temperature and a melting temperature that are close to each other. In this case, the glass begins to melt before oxide crystals are sufficiently formed. As a result, glass containing a large amount of B2O3 has difficulty in forming oxide crystals, which are a factor in improving crush resistance, and therefore does not easily improve crush resistance in high-temperature environments. From this perspective, the upper limit of the B2O3 content is set to 22 mol% or less. Note that, from the perspective of further improving crush resistance in high-temperature environments, the upper limit of the B2O3 content is preferably 21.5 mol% or less, more preferably 21 mol% or less, even more preferably 20.5 mol% or less, and particularly preferably 20 mol% or less.

[0024] (1-4)RO RO is an oxide of a Group 2 element (i.e., Mg, Ca, Ba, Sr, Be, and Ra). Oxides of Group 2 elements modify the glass skeleton and improve the fluidity of the glass after softening. Experiments have confirmed that RO-rich glass produces oxide crystals, such as BaMg2(SiO7) and CaB2O4, when heated at a temperature above the crystallization temperature and below the melting temperature. These oxide crystals have excellent heat resistance, significantly improving the crush resistance of glass joints in high-temperature environments. From this perspective, the technology disclosed herein sets the total RO content in the glass powder to 51 mol% or more. To further improve the crush resistance in high-temperature environments, the total RO content is preferably 52 mol% or more, more preferably 53 mol% or more, and particularly preferably 54 mol% or more. On the other hand, if the total RO content is too high, the components that constitute the glass skeleton (e.g., SiO2, BO3) will be insufficient, making it difficult to vitrify the complex oxide. For this reason, the total content of RO is limited to 60 mol% or less. From the viewpoint of ensuring a sufficient amount of components constituting the glass skeleton, the total content of RO is preferably 59.5 mol% or less, more preferably 59 mol% or less, even more preferably 58.5 mol% or less, and particularly preferably 58 mol% or less.

[0025] The thermal expansion coefficient of the glass can be controlled by adjusting the content ratio of each component (e.g., MgO, CaO, BaO) that constitutes the oxide RO of a Group 2 element. Specifically, oxides of Group 2 elements with a large atomic number have the effect of increasing the thermal expansion coefficient of the glass. Therefore, glass containing a large amount of CaO and BaO has a thermal expansion coefficient similar to that of common inorganic materials (e.g., SUS430) used in electrochemical cells, and therefore exhibits better durability. From this perspective, the CaO content in the glass powder is preferably 20 mol% or more, more preferably 21 mol% or more, and particularly preferably 22 mol% or more. The upper limit of the CaO content is not particularly limited and may be 30 mol% or less, 28 mol% or less, 26 mol% or less, or 24 mol% or less. On the other hand, the BaO content in the glass powder is preferably 20 mol% or more, more preferably 21 mol% or more, and particularly preferably 22 mol% or more. The upper limit of the BaO content is not particularly limited, and may be 30 mol % or less, 28 mol % or less, 26 mol % or less, or 24 mol % or less.

[0026] (1-5)ZnO Like RO, ZnO also modifies the glass skeleton. ZnO also enhances the fluidity of glass during melting. ZnO can also contribute to improving the durability (e.g., water resistance and thermal shock resistance) of glass joints after firing. ZnO also inhibits the formation of cristobalite crystals, which are SiO2-based crystals. This can prevent a decrease in the heat resistance of glass. To achieve these effects, the technology disclosed herein sets the ZnO content in glass particles to 5.5 mol% or more. To more effectively achieve the above-mentioned effects, the ZnO content is preferably 5.8 mol% or more, more preferably 6.0 mol% or more, even more preferably 6.2 mol% or more, and particularly preferably 6.4 mol% or more. To ensure sufficient content of other essential components (e.g., RO), the upper limit of the ZnO content is limited to 7 mol% or less (preferably 6.8 mol% or less, and more preferably 6.6 mol% or less).

[0027] (1-6) Other ingredients In addition to the essential components described above, the glass particles may contain optional components that can be contained in general glass. Examples of these optional components include Li2O, Na2O, K2O, TiO2, MnO, FeO, Fe2O3, Fe3O4, SnO, SnO2, V2O5, ZrO2, Nb2O5, CuO, Cu2O, La2O3, and CeO2. However, the total content of these optional components is preferably 5 mol% or less, more preferably 1 mol% or less, even more preferably 0.5 mol% or less, and particularly preferably 0.1 mol% or less. This ensures a sufficient content of the essential components, thereby more effectively demonstrating the effects of the technology disclosed herein (crush resistance in high-temperature environments).

[0028] (1-7) Particle size of glass powder In addition, the D of glass powder 50 The particle size is preferably 50 μm or less, more preferably 45 μm or less, even more preferably 40 μm or less, and particularly preferably 35 μm or less. 50 As the particle size becomes smaller, the fluidity of the glass increases during melting. This improves the density of the glass after firing, allowing for the formation of glass joints with excellent durability (heat resistance, chemical resistance, etc.). On the other hand, the D of glass powder 50 The lower limit of the particle size is preferably 0.2 μm or more, more preferably 1.0 μm or more, even more preferably 5.0 μm or more, and particularly preferably 10 μm or more. 50 As the particle size increases, the dispersibility of the glass powder becomes more stable, and the manufacturing stability of the glass bonding material (green sheet, paste, etc.) improves. 50 "Particle size" refers to the particle size corresponding to the cumulative 50% from the fine particle side in the volume-based particle size distribution measured by laser diffraction / light scattering method.

[0029] (1-8) Glass powder content Furthermore, when the total mass of the bonding material is taken as 100 wt%, the content of glass powder in the bonding material is preferably 45 wt% or more, more preferably 50 wt% or more, even more preferably 55 wt% or more, and particularly preferably 60 wt% or more. By using a bonding material containing a sufficient amount of glass powder, the bonding strength of the glass bonding portion after firing can be further improved. On the other hand, if the content of glass powder is reduced, the content of the resin material described below relatively increases. This can improve the fixation strength of the bonding material before firing. From this perspective, the content of glass powder is preferably 95 wt% or less, more preferably 94 wt% or less, even more preferably 92 wt% or less, and particularly preferably 90 wt% or less.

[0030] (2) Resin materials The resin material is used to improve the viscosity, fixability, formability, etc. of the bonding material. It is preferable that the resin material be burned in the preheating step S20 or the firing step S30 described below. This prevents impurities from being mixed into the glass bonding portion after firing. The specific resin material can be appropriately selected from conventionally known materials depending on the form of the bonding material, and does not limit the technology disclosed herein. For example, when a sheet-shaped bonding material (sealing green sheet) is used, a binder resin is used as the resin material, which maintains the shape of the bonding material by binding multiple glass powders. Examples of this binder resin include acrylic resin and polyether resin. On the other hand, when a paste-shaped bonding material (glass paste) is used, a thickener is used as the resin material, which dissolves in a solvent to adjust the viscosity of the paste. Examples of this thickener include cellulose-based polymers such as methyl cellulose, ethyl cellulose, and nitrocellulose. The content and molecular weight of the resin material are also adjusted appropriately depending on the form of the bonding material, and as they do not limit the technology disclosed herein, detailed description thereof will be omitted.

[0031] (3) Solvent The solvent is a liquid that can disperse the glass powder appropriately. The type and content of the solvent can be changed appropriately depending on the form of the bonding material. In consideration of safety, operating costs, environmental impact, etc., an aqueous solvent is preferable. Examples of the aqueous solvent include ion-exchanged water (deionized water), pure water, ultrapure water, and distilled water. The aqueous solvent may also contain a small amount of a non-aqueous solvent (such as a lower alcohol or a lower ketone) that can be uniformly mixed with water.

[0032] (4) Other additives The bonding material may also contain conventionally known additives, provided that they do not significantly impair the effects of the technology disclosed herein. Specific examples of such additives include plasticizers, sintering aids, antifoaming agents, antioxidants, preservatives, pH adjusters, colorants (pigments, dyes, etc.), and mold release agents.

[0033] 2. Preheating process S20 In the manufacturing method according to this embodiment, a preheating step S20 is performed before the firing step S30, which will be described later. The preheating step S20 heats the joining material at a preheating temperature that is equal to or higher than the crystallization temperature and lower than the melting temperature of the glass powder. Experiments have confirmed that the preheating step S20 significantly improves the crush resistance of the glass joining portion in a high-temperature environment. As described above, it is presumed that this improvement in crush resistance is due to the growth of oxide crystals containing Group 2 elements, which have excellent heat resistance, within the glass.

[0034] The heating temperature (preheating temperature) in this step is preferably 675°C or higher, more preferably 680°C or higher, even more preferably 685°C or higher, and particularly preferably 690°C or higher. This allows a large amount of well-grown oxide crystals to be produced inside the glass powder. On the other hand, if the preheating temperature is too high, the glass powder may melt, resulting in insufficient crystal growth. From this perspective, the upper limit of the preheating temperature is preferably 725°C or lower, more preferably 720°C or lower, even more preferably 715°C or lower, and particularly preferably 710°C or lower.

[0035] Furthermore, in the preheating step S20, the time for which the preheating temperature is maintained (preheating time) is preferably 0.5 hours or more (more preferably 1 hour or more, and particularly preferably 1.5 hours or more). This allows oxide crystals in the glass to grow more sufficiently. On the other hand, if the preheating step S20 is too long, abnormal precipitation of oxide crystals or deterioration of inorganic components may occur, which may result in a decrease in airtightness and bondability. From this perspective, the preheating time is preferably 4.5 hours or less, more preferably 4 hours or less, even more preferably 3.5 hours or less, and particularly preferably 3 hours or less. Furthermore, the preheating step S20 is preferably performed in an oxidizing atmosphere (oxygen concentration: 20% or more). This increases the diffusion coefficient of oxygen in the glass, thereby accelerating the growth of oxide crystals.

[0036] 3. Firing process S30 Next, in the firing step S30, the bonding material is fired at a firing temperature equal to or higher than the melting temperature of the glass powder. This melts the glass powder and penetrates into the gaps between the inorganic components. When the temperature is lowered and the molten glass solidifies in this state, a glass bonding joint is formed between the inorganic components. Here, the oxide crystals generated in the preheating step S20 do not melt during the firing step S30, but rather penetrate into the gaps between the inorganic components while dispersed in the molten glass.

[0037] The firing temperature in this step is preferably 725°C or higher, more preferably 735°C or higher, even more preferably 745°C or higher, and particularly preferably 750°C or higher. This allows the glass powder to be sufficiently melted to form a glass bonded body with excellent bondability. On the other hand, if the firing temperature is too high, the fluidity of the glass may be excessively improved. Furthermore, if the firing temperature is too high, the oxide crystals formed in the preheating step S20 may disappear. These phenomena may cause a decrease in the crush resistance of the glass bonded portion in a high-temperature environment. From this perspective, the upper limit of the preheating temperature is preferably 825°C or lower, more preferably 800°C or lower, even more preferably 790°C or lower, and particularly preferably 785°C or lower.

[0038] Furthermore, in the firing step S30, the time for maintaining the firing temperature (firing time) is preferably 0.5 hours or more (more preferably 1 hour or more, particularly preferably 1.5 hours or more). This allows the glass powder to melt more appropriately. Furthermore, by ensuring a firing time of at least a certain length, the fluidity of the glass can be maintained at a moderately high level, thereby achieving both good bondability and crush resistance. On the other hand, the firing time is preferably 4.5 hours or less, more preferably 4 hours or less, even more preferably 3.5 hours or less, and particularly preferably 3 hours or less. This prevents the fluidity of the glass from being excessively improved. Furthermore, the firing step S30 is preferably performed in an oxidizing atmosphere. This stabilizes the crystalline state and prevents deformation of the assembly during operation.

[0039] As described above, the manufacturing method according to this embodiment uses a joining material containing a borosilicate glass powder that is rich in RO and has a B2O3 content limited to a certain level. Then, by subjecting this glass powder to a preheating step S20, oxide crystals are grown within the glass. These oxide crystals have excellent heat resistance. This allows for the realization of a glass joining joint that has excellent crush resistance even in high-temperature environments.

[0040] The manufacturing method disclosed herein is not limited to the above-described embodiment, and various configurations can be appropriately modified as needed. For example, in the above-described embodiment, the preheating step S20 is performed after the application step S10. However, the preheating step need only be performed before the firing step, and is not limited to being performed after the application step. For example, a bonding material (sealing green sheet, glass paste, etc.) may be prepared using glass powder that has already been subjected to the preheating step. Then, by performing a firing process on this bonding material, a glass bonding portion with excellent crush resistance in a high-temperature environment can be formed.

[0041] ≪Assembly≫ Next, an electrochemical stack will be described as an example of an assembly manufactured by the manufacturing method disclosed herein. FIG. 2 is a perspective view showing an example of the structure of an electrochemical stack. This electrochemical stack 100 is formed by joining a plurality of electrochemical cells 1 via a metal connection plate 110. In this electrochemical stack 100, a glass joint is formed at the connection portion between a part of the electrochemical cell 1 (fuel electrode 20, air electrode 40) and the metal connection plate 110. A specific description will be given below.

[0042] 1. Electrochemical Cell In the electrochemical cell 1 (hereinafter also simply referred to as "cell") shown in FIG. 2, a fuel electrode 20, a solid electrolyte layer 30, and an air electrode 40 are stacked in this order.

[0043] The fuel electrode (anode) 20 is formed on the upper surface of the metal connection plate 110. When the electrochemical cell 1 is used as an SOFC, the fuel electrode 20 oxidizes hydrogen gas (H) to produce electrons (e - ) is generated. On the other hand, when the electrochemical cell 1 is used as an SOEC, the anode 20 functions as a layer that decomposes water (HO) to generate hydrogen gas (H). The anode 20 is, for example, a porous body containing a conductive material (a material having catalytic activity). The anode 20 preferably has a large number of pores, which can improve the breathability of the anode 20. Furthermore, the material of the anode 20 can be any conventional material that can be used for the anode of an electrochemical cell, without any particular restrictions. One example of a material for the anode 20 is a cermet of nickel (Ni) and yttria-stabilized zirconia (YSZ).

[0044] The solid electrolyte layer 30 is formed on the upper surface of the anode 20. The solid electrolyte layer 30 is a dense layer containing a solid electrolyte having oxygen ion conductivity. For this solid electrolyte, any conventionally known material that can be used for the solid electrolyte layer of an electrochemical cell can be used without particular limitation. Examples of solid electrolytes include yttria-stabilized zirconia (YSZ), gadolinia-doped ceria (GDC), calcia-stabilized zirconia (CSZ), scandia-stabilized zirconia (ScSZ), and lanthanum gallate (LaGaO).

[0045] The air electrode 40 is formed on the upper surface of the solid electrolyte layer 30. For this air electrode 40, any conventionally known material that can be used for the air electrode of an electrochemical cell can be used without any particular limitation. An example of the material for the air electrode 40 is lanthanum strontium cobalt composite oxide (LSC, for example, La 0.6 Sr 0.4 CoO3) and lanthanum strontium cobalt iron composite oxides (LSCF, e.g., La 0.6 Sr 0.4 Co 0.2 Fe 0.8 Examples include perovskite oxides containing La, Sr, and Co, such as LSCF and LSSC. The substitution ratios of the A and B sites of these LSC and LSCF can be varied, and an appropriate substitution ratio can be used depending on the desired ionic conductivity, reduction expansion coefficient, etc.

[0046] 2. Metallic connecting plate Next, the metal connection plate 110 is a conductive member interposed between the multiple electrochemical cells 1. This metal connection plate 110 electrically connects each of the multiple electrochemical cells 1. The metal connection plate 110 also has a gas flow channel for supplying gas to the electrochemical cells 1. For example, a first gas flow channel 112 extending in the depth direction Y is formed on the lower surface of the metal connection plate 110 facing the air electrode 40 of the electrochemical cell 1. A plurality of first gas flow channels 112 are provided at predetermined intervals in the width direction X. The first gas flow channel 112 communicates with the air electrode 40 of the electrochemical cell 1. Meanwhile, a second gas flow channel 114 extending in the width direction X is formed on the upper surface of the metal connection plate 110 facing the fuel electrode 20. A plurality of second gas flow channels 114 are provided at predetermined intervals in the depth direction Y. The second gas flow channel 114 communicates with the fuel electrode 20.

[0047] 3. Restraining member Although not shown, the electrochemical stack 100 also includes a restraining member. This restraining member restrains the stack, which is made by stacking the electrochemical cells 1 and the metal connection plates 110, along the stacking direction of the stack (height direction Z in FIG. 2). This fixes the electrochemical cells 1 and the metal connection plates 110, and the electrochemical stack 100 is constructed. By restraining the stack in this manner, it is possible to prevent gaps from occurring at the interface between the cells 1 and the metal connection plates 110. As a result, it is possible to prevent gas leakage, poor contact, and the like from occurring at the interface between the cells 1 and the metal connection plates 110.

[0048] 4. Glass joint In the electrochemical stack 100 configured as described above, a glass joint is formed between the electrochemical cell 1 and the metal connection plate 110. Specifically, the upper surface of the air electrode 40 of the electrochemical cell 1 contacts the metal connection plate 110. The lower surface of the fuel electrode 20 also contacts the metal connection plate 110. In the electrochemical stack 100 shown in FIG. 2, these contact interfaces serve as the connection portions between the inorganic components. The glass joint in this embodiment is formed at these connection portions. This makes it possible to suppress gas leakage from the contact interfaces. Note that the glass joint may be formed at any connection portion between multiple inorganic components included in the electrochemical stack, and is not limited to the above configuration. For example, the glass joint may be formed between a solid electrolyte layer and a metal component (such as a gas pipe or a metal plate) or between multiple metal components.

[0049] In this electrochemical stack 100, a confining pressure is applied in the height direction Z by the confining member. As a result, a large external stress is constantly applied to the glass joint between the electrochemical cell 1 and the metal connection plate 110. At this time, the electrochemical stack 100 may be heated to 750°C or higher during operation. If this softens the glass joint, the confining pressure may cause the glass joint to collapse. In contrast, the glass joint in this embodiment contains oxide crystals grown in the preheating step S20. This prevents deformation (collapse) of the glass joint even when exposed to a high-temperature environment.

[0050] According to experiments conducted by the present inventors, borosilicate glass (glass joint after manufacture) in which oxide crystals have grown through the preheating step S20 has a crystallinity of 30 or more as determined by X-ray diffraction. This means that when preheating is performed on a joint material containing glass powder of a predetermined composition, many oxide crystals are generated in the glass joint after firing. It is believed that the generation of these oxide crystals improves the crush resistance of the glass joint in a high-temperature environment. To achieve better crush resistance, the crystallinity of the glass joint is preferably 35 or more, more preferably 40 or more, and even more preferably 45 or more.

[0051] In addition, the glass joint contains BaMg2(Si2O7), CaB2O4, Ca2B2O5, Ca3B2O6, BaAl2O4, Ba3Al2O6, Ba4Al2O7, BaMgSiO4, BaZnSiO4, Ba3(BO3)2, Al2Ca 0.5 SiO 11 Experiments have confirmed that oxide crystals such as these are formed. It is expected that these oxide crystals containing Group 2 elements contribute greatly to improving the crush resistance of glass joints. Furthermore, oxide crystals that do not contain Group 2 elements, such as SiO2 (coesite), SiO2 (quartz), and MgO, are sometimes found in glass joints after manufacture. These oxide crystals do not impair crush resistance in high-temperature environments, so they may be present in glass joints.

[0052] An example of an assembly manufactured by the manufacturing method disclosed herein has been described above. However, the target (assembly) to which the technology disclosed herein is applied is not limited to an electrochemical stack. The technology disclosed herein can be widely applied to structures in which external stress may be applied to glass joints when exposed to a high-temperature environment. Another example of such a structure is a pressure sensor used in a high-temperature environment. The technology disclosed herein can be used to join multiple components that make up this pressure sensor. The technology disclosed herein can also be used in exhaust gas purification systems, ceramic heater components, and the like. Because these devices are also exposed to a high-temperature environment and are subjected to external stress, the technology disclosed herein can be suitably applied to them.

[0053] [Test example] Below, several test examples relating to the technology disclosed herein will be described, but it is not intended that the technology disclosed herein be limited to those shown in these test examples.

[0054] 1. Test conditions In this test, 25 types of test examples (Examples 1 to 17 and Comparative Examples 1 to 8) were prepared, each with different compositions of the encapsulating green sheets, different conditions for the preheating step, and different conditions for the firing step. Detailed test conditions will be described below.

[0055] In this test, a slurry was prepared by mixing 33.0 wt% glass powder, 13.2 wt% binder (acrylic resin), 0.9 wt% release agent, 0.5 wt% plasticizer, 0.1 wt% antifoaming agent, and 52.3 wt% water. Next, a granulated powder with a particle size of approximately 50 to 100 μm was produced from this slurry using a spray-drying method. The granulated powder was then rolled using a roll molding machine to form a 0.7 mm thick green sheet for sealing. Seven types of glass (glasses A to G) with different compositions were used in this test. The compositions of each glass are shown in Tables 1 and 2.

[0056] Next, the green sheet after molding was punched with a die to prepare a test piece with a diameter of 10 mm. Next, two sheets of metal foil made of SUS430 were prepared, and the test piece was placed between the metal foils. Then, a weight of 120 g / cm was placed on this laminate. 2 A heat treatment was performed in an air atmosphere while applying a load of 1000 kJ / cm2, thereby obtaining a laminate in which two metal foils were bonded via a glass bonding portion. Specifically, in Examples 1 to 17 and Comparative Examples 2 and 7, a preheating step at a relatively low temperature was performed, followed by a firing step at a relatively high temperature. On the other hand, in Comparative Examples 1, 3 to 6, and 8, only the firing step was performed without performing the preheating step. The specific heating conditions for each example are shown in Tables 1 and 2.

[0057] 2.Evaluation Test (1) Crush resistance evaluation In the above-mentioned heat treatment, the diameter D1 of the green sheet before the firing process and the diameter D2 of the glass joint after the firing process were measured. Then, the crushing ratio M for each example was calculated based on the following formula (1). The results are shown in Tables 1 and 2. M = 100 × [(D2 - D1) / D1] (1)

[0058] (2) Heat resistance evaluation The laminate was placed in a firing furnace equipped with a thickness displacement meter and heated to 230 g / cm 2 The temperature inside the furnace was raised while applying a load of 1000 kJ / cm. The temperature at which the thickness of the laminate began to decrease was measured, and this temperature was considered to be the "heat resistance temperature of the glass joint." The results are shown in Tables 1 and 2.

[0059] (3) Bondability evaluation In this bondability evaluation, the metal foil was first peeled off from only one side of the fired laminate. Then, the remaining metal foil was grasped, and the fired green sheet (glass bonded portion) was held facing downward in the direction of gravity for 3 minutes. If the glass bonded portion peeled off from the metal foil and fell freely, it was evaluated as "×", and if it did not fall freely, it was evaluated as "◎". The results are shown in Tables 1 and 2.

[0060] [Table 1]

[0061] [Table 2]

[0062] As shown in Table 1, in Examples 1 to 17, crush resistance, heat resistance, and bondability were all achieved at high levels. On the other hand, in Comparative Examples 3 to 5, despite using the same glasses A, B, and C as in the Examples, crush resistance and heat resistance were not sufficiently improved. This shows that in order to improve crush resistance in a high-temperature environment, it is necessary to carry out a preheating process before the firing process.

[0063] On the other hand, in Comparative Examples 2 and 7, despite the preheating process being performed under the same conditions as in Examples 1 to 17, any one of the crush resistance, heat resistance, and bondability was significantly reduced. This indicates that in order to appropriately improve these performances, it is necessary to adjust the composition of the glass powder to which preheating is applied. For example, in Comparative Example 2, the total RO content was less than 51 mol% and the B2O3 content was greater than 22 mol%, which is presumably why the crush resistance was reduced. This indicates that in order to improve the crush resistance in high-temperature environments, it is necessary to use borosilicate glass in which the RO and B2O3 contents are adjusted to an appropriate range. Furthermore, in Comparative Example 7, the SiO2 content was greater than 22 mol%, the Al2O3 content was greater than 4 mol%, and the B2O3 content was less than 12 mol%, which is presumably why the bondability was significantly reduced. This indicates that in order to form a glass joint with excellent bondability, it is necessary to adjust the content ratios of SiO2, Al2O3, and B2O3 within a certain range.

[0064] 3. Analysis of Glass Joints Next, the crystalline structure of the glass joints was analyzed for each of Examples 1, 4, 9, 12, 15, and Comparative Example 1. Specifically, the metal foil was peeled off from the fired laminate to recover the glass joints (fired green sheets). The glass joints were then pulverized into powder using a mortar and pestle. X-ray diffraction (XRD) measurements were then performed on the powdered glass joints to obtain XRD charts. The crystallinity of the glass joints was then examined based on the peaks on the XRD chart. Specifically, the oxide crystal peak area and the halo peak area were measured at 2θ = 25° to 35°, where the amorphous peak (halo peak) of the XRD chart of the glass joints is prominent. The crystallinity of the glass joints was then calculated using the following formula (2): Crystallinity (%) = {crystal oxide peak area / (crystal oxide peak area + halo peak area)} × 100 (2)

[0065] [Table 3]

[0066] As shown in Table 3, the crystallinity of the glass joints in Examples 1, 4, 9, 12, and 15 was 30 or higher. This indicates that when a joint material containing glass powder of a specified composition is preheated, many oxide crystals are generated in the glass joints after firing. It is presumed that the generation of these oxide crystals significantly affects the crush resistance of the glass joints in high-temperature environments. Furthermore, the crystal structure was identified based on the XRD chart, and it was found that the glass joints in Examples 1, 4, 9, 12, and 15 contained BaMg2(SiO7), CaB2O4, Ca2B2O5, Ca3B2O6, BaAl2O4, Ba3Al2O6, Ba4Al2O7, BaMgSiO4, BaZnSiO4, Ba3(BO3)2, Al2Ca 0.5 SiO 11 It was confirmed that SiO2 (coesite), SiO2 (quartz), and MgO were produced.

[0067] While specific examples of the technology disclosed herein have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above.

[0068] The technology disclosed herein includes the following items 1 to 10. The following items 1 to 10 are not limited to the above-described embodiment.

[0069] [Item 1] 1. A method for manufacturing an assembly in which a plurality of inorganic components are bonded via a glass bond, comprising: an application step of applying a bonding material containing glass powder to a connection portion where the plurality of inorganic components are in contact with each other; a firing step of firing the bonding material at a firing temperature equal to or higher than the melting temperature of the glass powder to form the glass bonding portions between the plurality of inorganic components; Equipped with The glass powder in the bonding material has the following composition in terms of oxide molar ratio: SiO2 14~22mol%; Al2O3 2~4mol%; B2O3 12~22mol%; RO 51-60 mol%; ZnO 5.5 to 7 mol% (where RO is an oxide of a Group 2 element.) consists essentially of a preheating step of heating the joining material at a preheating temperature that is equal to or higher than the crystallization temperature of the glass powder and equal to or lower than the melting temperature of the glass powder, before the firing step.

[0070] [Item 2] Item 2. The method according to item 1, wherein the firing temperature is 725°C or higher and 825°C or lower.

[0071] [Item 3] 3. The method according to claim 2, wherein the firing temperature is maintained for 0.5 hours or more in the firing step.

[0072] [Item 4] 4. The method according to item 2 or 3, wherein the preheating temperature is 675°C or higher and 725°C or lower.

[0073] [Item 5] 3. The method according to claim 2, wherein the preheating step maintains the preheating temperature for 0.5 hours or more.

[0074] [Item 6] 6. The manufacturing method according to any one of items 1 to 5, wherein the content of the glass powder is 45 wt% or more and 95 wt% or less when the total mass of the bonding material is 100 wt%.

[0075] [Item 7] 7. The method according to any one of items 1 to 6, wherein the inorganic parts are components of an electrochemical cell.

[0076] [Item 8] An assembly manufactured by the manufacturing method described in any one of items 1 to 7, a plurality of inorganic components that contact each other at connection portions; a glass joint formed at the connection portion; It is equipped with The glass joint has the following composition in terms of oxide molar ratio: SiO2 14~22mol%; Al2O3 2~4mol%; B2O3 12~22mol%; RO 51-60 mol%; ZnO 5.5 to 7 mol% (where RO is an oxide of a Group 2 element.) and having a crystallinity of 30 or more as determined by X-ray diffraction.

[0077] [Item 9] Item 9. The assembly of item 8, wherein the glass joint comprises at least an oxide crystal containing a Group 2 element.

[0078] [Item 10] The oxide crystals include BaMg2(Si2O7), CaB2O4, Ca2B2O5, Ca3B2O6, BaAl2O4, Ba3Al2O6, Ba4Al2O7, BaMgSiO4, BaZnSiO4, Ba3(BO3)2, Al2Ca 0.5 SiO 11 10. The assembly according to item 9, wherein the at least one selected from the group consisting of:

Claims

1. 1. A method for manufacturing an assembly in which a plurality of inorganic components are bonded via a glass bond, comprising: an application step of applying a bonding material containing glass powder to a connection portion where the plurality of inorganic components are in contact with each other; a firing step of firing the bonding material at a firing temperature equal to or higher than the melting temperature of the glass powder to form the glass bonding portions between the plurality of inorganic components; Equipped with The glass powder in the bonding material has the following composition in terms of oxide molar ratio: Yes ２ 14~22mmol%; Al ２ O ３ 2~4 mol%; B ２ O ３ 12~22 mol%; RO 51~60mol%; Zinc 5.5~7 mol% (wherein RO is an oxide of a Group 2 element.) consists essentially of a preheating step of heating the joining material at a preheating temperature that is equal to or higher than the crystallization temperature of the glass powder and equal to or lower than the melting temperature of the glass powder, before the firing step.

2. The method according to claim 1 , wherein the firing temperature is 725° C. or higher and 825° C. or lower.

3. The method according to claim 2 , wherein the firing step maintains the firing temperature for 0.5 hours or more.

4. The method according to claim 2 or 3, wherein the preheating temperature is 675°C or higher and 725°C or lower.

5. The method according to claim 2 , wherein the preheating step maintains the preheating temperature for 0.5 hours or more.

6. The manufacturing method according to claim 1 , wherein the content of the glass powder is 45 wt % or more and 95 wt % or less when the total mass of the bonding material is 100 wt %.

7. The method of claim 1 , wherein the inorganic components are components of an electrochemical cell.

8. An assembly manufactured by the manufacturing method of claim 1, a plurality of inorganic components that contact each other at connection portions; a glass joint formed at the connection portion; It is equipped with The glass bonding portion has the following composition in terms of oxide molar ratio: Yes ２ 14~22mmol%; Al ２ O ３ 2~4 mol%; B ２ O ３ 12~22 mol%; RO 51~60mol%; Zinc 5.5~7 mol% (wherein RO is an oxide of a Group 2 element.) and having a crystallinity of 30 or more as determined by X-ray diffraction.

9. The assembly of claim 8 , wherein the glass joint comprises at least an oxide crystal containing a Group 2 element.

10. The oxide crystal is BaMg ２ (Si ２ O ７ ), CaB ２ O ４ , Ca ２ B ２ O ５ , Ca ３ B ２ O ６ , BaAl ２ O ４ , Ba ３ Al ２ O ６ , Ba ４ Al ２ O ７ , BaMgSiO ４ , BaZnSiO ４ , Ba ３ (BO ３ ) ２ , Al ２ Ca ０．５ Si ３ O １１ The assembly according to claim 9, wherein the at least one selected from the group consisting of:

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