WO2017169308A1 - Crystalline glass composition - Google Patents

Abstract

Provided is a crystalline glass composition which has a fluidity that is suitable for adhesion, has a high coefficient of thermal expansion after thermal treatment, and has excellent heat resistance after adhesion. The crystalline glass composition is characterized by including, in mol%, greater than 57 to 80% of SiO₂+CaO, greater than 0 to 40% of MgO+BaO, greater than 10 to 40% of ZnO, and greater than 0 to 15% of La₂O₃.

Description

Crystalline glass composition

The present invention relates to a crystalline glass composition, and more specifically to a crystalline glass composition used for the purpose of bonding a metal such as SUS or Fe, or a high expansion ceramic such as ferrite or zirconia.

In recent years, a fuel cell has been attracting attention as an effective technology that has high energy efficiency and can greatly reduce CO ₂ emissions. The type of fuel cell is classified according to the electrolyte used. For example, as used in industrial applications, phosphoric acid type (PAFC), molten carbonate type (MCFC), solid oxide type (SOFC), solid polymer type (PEFC) There are four types. Among them, the solid oxide fuel cell (SOFC) has the characteristics that the power generation efficiency is the highest among the fuel cells because the internal resistance of the cell is small, and the production cost can be reduced because it is not necessary to use a precious metal for the catalyst. Have. Therefore, it is a system that can be widely applied from a small-scale use such as home use to a large-scale use such as a power plant.

The structure of a general flat plate type SOFC is shown in FIG. As shown in FIG. 1, a general plate-type SOFC is composed of an electrolyte 1 made of a ceramic material such as yttria stabilized zirconia (YSZ), an anode 2 made of Ni / YSZ, and (La, Ca) CrO ₃ or the like. The cathode 3 has a cell in which the layers are integrated. Further, a passage for fuel gas (fuel channel 4a) is formed, and a first support substrate 4 in contact with the anode 2 and a second support substrate 5 in which an air passage (air channel 5a) is formed and in contact with the cathode 3 are formed. Fixed to the top and bottom of the cell. The first support substrate 4 and the second support substrate 5 are made of metal such as SUS, and are fixed to the cells so that the gas passages are orthogonal to each other.

In the flat plate type SOFC having the above-described structure, various gases such as hydrogen (H ₂ ), city gas, natural gas, biogas, and liquid fuel flow through the fuel channel 4a, and at the same time, air or oxygen (O ₂ ) flows through the air channel 5a. Shed. At this time, a reaction of 1 / 2O ₂ + 2e ⁻ → O ²⁻ occurs at the cathode, and a reaction of H ₂ + O ²⁻ → H ₂ O + 2e ⁻ occurs at the anode. By this electrochemical reaction, chemical energy is directly converted into electric energy and can be generated. In order to obtain a high output, an actual flat plate type SOFC has a number of layers of the structure shown in FIG.

In manufacturing the structure, it is necessary to hermetically seal each component so that the gas flowing to the anode side and the cathode side does not mix. For this purpose, a method of hermetically sealing by sandwiching an inorganic sheet-shaped gasket such as mica, vermiculite, alumina, etc. has been proposed, but this method is likely to cause a small amount of gas leak, resulting in a decrease in fuel use efficiency. It has become. In order to solve the problem, a method of melting and bonding constituent members using an adhesive material made of glass has been studied.

Since a high expansion material such as metal or ceramic is used as a constituent member of the structure, the adhesive material to be used needs to have a thermal expansion coefficient compatible with these high expansion materials. The SOFC has a high temperature range (operation temperature range) where an electrochemical reaction occurs (600 to 950 ° C.), and is operated for a long time in the temperature range. Therefore, the adhesive material is required to have high heat resistance so that even if it is exposed to a high temperature for a long period of time, the hermeticity or adhesion deterioration due to melting of the bonded portion does not occur.

As a high expansion adhesive material made of glass, Patent Document 1 discloses a crystalline glass composition exhibiting high expansion characteristics by precipitating CaO—MgO—SiO ₂ -based crystals upon heat treatment. Patent Document 2 discloses a SiO ₂ —B ₂ O ₃ —SrO-based amorphous glass composition capable of obtaining stable gas seal characteristics.

International Publication No. 2009/0117173 JP 2006-56769 A

Since the crystalline glass composition described in Patent Document 1 has a high temperature viscosity, it is difficult to soften and flow during heat treatment, and it is difficult to obtain a dense sintered body. As a result, there is a problem that it is difficult to obtain a stable sealing property. In addition, since the amorphous glass composition disclosed in Patent Document 2 has a glass transition point of around 600 ° C., the bonded portion melts under a high-temperature operating environment of about 600 to 800 ° C. There is a problem that adhesiveness cannot be secured.

In view of the above, an object of the present invention is to provide a crystalline glass composition having fluidity suitable for bonding, a high thermal expansion coefficient after heat treatment, and excellent heat resistance after bonding. .

As a result of various experiments conducted by the present inventor, it has been found that the above problem can be solved by a glass composition having a specific composition.

That is, the crystalline glass composition of the present invention contains, in mol%, SiO ₂ + CaO 57 to 80%, MgO + BaO 0 to 40%, ZnO 10 to 40%, La ₂ O ₃ 0 to 15%. It is characterized by doing. Here, “SiO ₂ + CaO” means the total amount of each content of SiO ₂ and CaO, and “MgO + BaO” means the total amount of each content of MgO and BaO.

In the crystalline glass composition of the present invention, SiO ₂ and CaO are components that improve fluidity, and by defining the total amount thereof as described above, fluidity suitable for adhesion (sealing) is obtained. Can do. In addition, by regulating the content of MgO, BaO, ZnO and La ₂ O ₃ which are high-expansion crystal components that precipitate during heat treatment as described above, the adhesion location after heat treatment has a high coefficient of thermal expansion, The property is also good. Therefore, even if it is used at a high temperature for a long period of time, the bonded portion is difficult to melt, and the deterioration of the airtightness and adhesiveness of the bonded portion can be suppressed.

“Crystallinity” means the property of precipitating crystals from the glass matrix upon heat treatment. “Heat treatment” means heat treatment at a temperature of 800 ° C. or higher for 10 minutes or longer.

The crystalline glass composition of the present invention preferably contains substantially no R ₂ O (R represents an alkali metal) and P ₂ O ₅ . R ₂ O and P ₂ O ₅ are liable to volatilize by heat treatment and may adversely affect the power generation characteristics such as lowering the electrical insulation of the SOFC component. Therefore, by not containing these components substantially, it can suppress that an electric power generation characteristic falls unjustly. “Substantially not contained” means not intentionally contained, and does not exclude inevitable contamination. Specifically, it means that the content of the corresponding component is less than 0.1 mol%.

The crystallizable glass composition of the present invention to deposit at least one crystal selected from _{MgO · SiO 2, BaO · 2MgO} · 2SiO 2, 2SiO 2 · 2ZnO · BaO and _{La 2 O} 3 · 2SiO 2 by heat treatment Is preferred. With this configuration, it is possible to increase the bonding location and improve the heat resistance, and it is suitable for use in bonding or coating high expansion materials such as metals and ceramics.

The crystalline glass composition of the present invention preferably has a thermal expansion coefficient of 85 × 10 ⁻⁷ / ° C. or higher in a temperature range of 30 to 950 ° C.

結晶 The crystalline glass composition of the present invention preferably has a difference between the softening point and the crystallization temperature of 85 ° C or higher. If the difference between the softening point and the crystallization temperature is large, crystallization is difficult to start before flowing, so that fluidity suitable for adhesion can be easily obtained.

The crystalline glass composition of the present invention comprises, in mol%, SiO ₂ 40-70%, MgO 5-40%, BaO 5-40%, ZnO over 10-40%, CaO 3-30%, La ₂ O ₃ It is preferable to contain more than 0 to 15%.

The crystalline glass composition of the present invention is suitable for bonding.

The crystalline glass composition of the present invention has fluidity suitable for adhesion, has a high thermal expansion coefficient after heat treatment, and is excellent in heat resistance after adhesion. Therefore, even if it is used at a high temperature for a long period of time, the bonded portion is difficult to melt, and the deterioration of the airtightness and adhesiveness of the bonded portion can be suppressed.

It is a typical perspective view which shows the basic structure of SOFC.

The crystalline glass composition of the present invention contains, in mol%, SiO ₂ + CaO 57 to 80%, MgO + BaO 0 to 40%, ZnO 10 to 40%, La ₂ O ₃ 0 to 15%. The reason for limiting the glass composition as described above is shown below. In the following description regarding the content of each component, “%” means “mol%” unless otherwise specified.

SiO ₂ and CaO are components for improving fluidity. The content of SiO ₂ + CaO is more than 57 to 80%, preferably 57.1 to 78%, particularly preferably 57.2 to 76%. When the content of SiO ₂ + CaO is too small, fluidity suitable for bonding becomes difficult to obtain. On the other hand, if the content of SiO ₂ + CaO is too large, it is difficult for high expansion crystals to precipitate during heat treatment, the melting temperature becomes high and melting becomes difficult, or defects such as devitrification easily occur during melting. Become.

Further preferred range of the content of SiO ₂ and CaO are as follows.

SiO ₂ is a component for precipitating highly expanded crystals by heat treatment, and has the effect of improving water resistance and heat resistance in addition to improving fluidity. The SiO ₂ content is preferably 40 to 70%, 41 to 69%, particularly 41 to 65%. When the content of SiO ₂ is too small, fluidity suitable for bonding becomes difficult to obtain. On the other hand, when the content of SiO ₂ is too large, crystals are hardly precipitated even after heat treatment. In addition, the meltability tends to decrease.

The CaO content is preferably 3 to 30%, 3 to 29%, and particularly preferably 3 to 28%. When there is too little content of CaO, it will become difficult to obtain the fluidity | liquidity suitable for adhesion | attachment. On the other hand, when there is too much content of CaO, it will become easy to devitrify during melting.

MgO and BaO are components for precipitating highly expanded crystals by heat treatment. The content of MgO + BaO is more than 0 to 40%, preferably 1 to 39%, 2 to 38%, 3 to 37%, 5 to 37%, particularly preferably 7 to 37%. When there is too little content of MgO + BaO, it will become difficult to precipitate a highly expanded crystal | crystallization at the time of heat processing, and heat resistance will fall easily. On the other hand, when there is too much content of MgO + BaO, there exists a tendency for the vitrification range to become narrow and it becomes easy to devitrify. In addition, the difference between the softening point and the crystallization temperature becomes small, and the fluidity tends to decrease.

Note that the MgO content is preferably 5 to 40%, 5 to 39%, particularly 6 to 38%. The BaO content is preferably 5 to 40%, 5 to 39%, particularly 6 to 38%.

ZnO is a component for precipitating highly expanded crystals by heat treatment. The content of ZnO is more than 10 to 40%, preferably 10.2 to 38%, 10.5 to 36%, particularly preferably 10.5 to 34%. When the content of ZnO is too small, it becomes difficult for highly expanded crystals to precipitate during the heat treatment, and the heat resistance tends to decrease. On the other hand, when there is too much content of ZnO, there exists a tendency for the vitrification range to become narrow and it becomes easy to devitrify. In addition, the difference between the softening point and the crystallization temperature becomes small, and the fluidity tends to decrease.

La ₂ O ₃ is a component for precipitating highly expanded crystals by heat treatment. Moreover, it is a component which expands the vitrification range and facilitates vitrification. The content of La ₂ O ₃ is more than 0 to 15%, preferably 0.5 to 14%, particularly preferably 1 to 13%. When the content of La ₂ O ₃ is too small, the effect is difficult to obtain. On the other hand, when the content of La ₂ O ₃ is too large, it easily devitrified during or heat treatment in the melt flowability becomes difficult to obtain suitable adhesion.

In the crystalline glass composition of the present invention, TiO ₂ , ZrO ₂ , SnO ₂ , WO ₃ or the like may be added up to 2% as components other than those described above. However, since R ₂ O (R represents an alkali metal) and P ₂ O ₅ are liable to be volatilized by heat treatment and may adversely affect the power generation characteristics such as reducing the electrical insulation of the SOFC component, It is preferable not to contain it.

The crystalline glass composition of the present invention having the above composition precipitates highly expanded crystals by heat treatment. As the high expansion crystal _include at least one selected from _{MgO · SiO 2, BaO · 2MgO} · 2SiO 2, 2SiO 2 · 2ZnO · BaO and _{La 2 O} 3 · 2SiO 2. The thermal expansion coefficient of the crystalline glass composition after the heat treatment is 85 × 10 ⁻⁷ / ° C. or higher, 86 × 10 ⁻⁷ / ° C. or higher, 87 × 10 ⁻⁷ / ° C. or higher, particularly 88 × 10 ⁻⁷ / ° C. or higher. It is preferable that Note that the crystal glass of the present invention tends to have a high degree of crystallinity after heat treatment. In addition, precipitated crystals have a high melting point and are difficult to flow even when heat-treated again, so that heat resistance can be maintained over a long period of time.

In the crystalline glass composition of the present invention, the difference between the softening point and the crystallization temperature is preferably 85 ° C. or higher, more preferably 90 ° C. or higher, and further preferably 95 ° C. or higher. If the difference between the softening point and the crystallization temperature is small, crystallization starts before flowing, and fluidity decreases.

The crystalline glass composition of the present invention is made of magnesia (MgO), zinc white (ZnO), zirconia (ZrO ₂ ), titania (TiO ₂ ), alumina (Al ₂ O ₃ ), etc. for fluidity adjustment. You may add and use powder as a filler powder. The addition amount of the filler powder is preferably 0 to 10 parts by mass, 0.1 to 9 parts by mass, particularly 1 to 8 parts by mass with respect to 100 parts by mass of the crystalline glass composition. When there is too much addition amount of filler powder, fluidity | liquidity will fall easily. It is preferable to use a filler powder having a d50 particle size of about 0.2 to 20 μm.

Next, an example of a method for producing the crystalline glass composition of the present invention and a method of using the crystalline glass composition of the present invention as an adhesive material will be described.

First, the raw material powder prepared so as to have the above composition is melted at about 1400 to 1600 ° C. for about 0.5 to 2 hours until a homogeneous glass is obtained. Next, after the molten glass is formed into a film or the like, it is pulverized and classified to produce a glass powder made of the crystalline glass composition of the present invention. The particle size (d50) of the glass powder is preferably about 2 to 20 μm. Various filler powders are added to the glass powder as necessary.

Next, a glass paste is prepared by adding a vehicle to glass powder (or a mixed powder of glass powder and filler powder) and kneading. The vehicle contains, for example, a plasticizer, a dispersant and the like in addition to an organic solvent and a resin.

The organic solvent is a material for pasting glass powder, such as terpineol (Ter), diethylene glycol monobutyl ether (BC), diethylene glycol monobutyl ether acetate (BCA), 2,2,4-trimethyl-1,3-pentadiol. Monoisobutyrate, dihydroterpineol and the like can be used alone or in combination. The content is preferably 10 to 40% by mass.

Resin is a component that increases the film strength after drying and imparts flexibility, and its content is generally about 0.1 to 20% by mass. As the resin, a thermoplastic resin, specifically, polybutyl methacrylate, polyvinyl butyral, polymethyl methacrylate, polyethyl methacrylate, ethyl cellulose and the like can be used, and these are used alone or in combination.

The plasticizer is a component that controls the drying speed and imparts flexibility to the dried film, and the content thereof is generally about 0 to 10% by mass. As the plasticizer, butylbenzyl phthalate, dioctyl phthalate, diisooctyl phthalate, dicapryl phthalate, dibutyl phthalate and the like can be used, and these are used alone or in combination.

As the dispersant, an ionic or nonionic dispersant can be used. As the ionic type, a carboxylic acid, a dicarboxylic acid type polycarboxylic acid type, an amine type dispersant, and the nonionic type as a polyester condensation type. Alternatively, a polyhydric alcohol ether type dispersant can be used. The amount used is generally 0 to 5% by mass.

Next, the paste is applied to the bonding portion of the first member made of metal or ceramic and dried. Further, the second member made of metal or ceramic is fixed in a state where it is in contact with the dry paste film, and heat treated at 800 to 1050 ° C. By this heat treatment, the glass powder once softens and flows, and the first and second members are fixed, and crystals are precipitated. In this manner, a joined body can be obtained in which the first member and the second member are bonded by the sealing portion made of the crystalline glass composition of the present invention.

The crystalline glass composition of the present invention can be used for purposes such as coating and filling in addition to adhesion. Further, it can be used in a form other than paste, specifically in the form of powder, green sheet, tablet or the like. For example, the form which fills glass powder with a lead wire in the cylinder which consists of metal or ceramics, heat-processes, and performs airtight sealing is mentioned. Further, a green sheet molded preform, a tablet produced by powder press molding, or the like is placed on a member made of metal or ceramic, and can be coated by heat treatment and softening and flowing.

Hereinafter, although the crystalline glass composition of the present invention will be described based on examples, the present invention is not limited to these examples.

Tables 1 and 2 show Examples (Sample Nos. 1 to 9) and Comparative Examples (Sample Nos. 10 to 11) of the present invention.

Each sample was prepared as follows.

The raw materials prepared so as to have the respective compositions in the table were melted at 1400-1600 ° C. for about 1 hour, and then poured out between a pair of rollers to form a film. The obtained film-like molded product was pulverized with a ball mill and further classified to obtain a sample (crystalline glass composition powder) having a particle size (d50) of about 10 μm.

For the obtained samples, the thermal expansion coefficient, softening point, fluidity, precipitated crystals, crystallization temperature, and crystal melting point were measured or evaluated by the following methods. The results are shown in Tables 1 and 2.

The coefficient of thermal expansion is based on JIS R3102 using a measurement sample obtained by press-molding each sample, heat-treating at 1000 ° C. for 3 hours, and polishing into a cylindrical shape having a diameter of 4 mm and a length of 20 mm. Values in a temperature range of 30 to 950 ° C. were obtained.

Softening point, crystallization temperature, and crystal melting point were measured using a macro-type differential thermal analyzer. Specifically, for each glass powder sample, in the chart obtained by measuring up to 1050 ° C. using a macro-type differential thermal analyzer, the fourth inflection point value is the softening point and the strong exothermic peak is crystallized. The endothermic peak obtained after temperature and crystallization was defined as the crystalline melting point. In addition, it means that it means that the crystal | crystallization exists stably also under high temperature, so that crystal | crystallization melting | fusing point is high, and it can be judged that heat resistance is high.

The fluidity was evaluated as follows. A glass powder sample having a specific gravity was put into a mold having a diameter of 20 mm, press-molded, and then fired on a SUS430 plate at 850 to 1050 ° C. for 15 minutes. Evaluations were made as “成形” when the flow diameter of the molded body after firing was 18 mm or more, “◯” when it was less than 16 to 18 mm, and “X” if it was less than 16 mm.

Precipitated crystals were identified by performing XRD (X-ray diffraction) measurement for each sample and comparing with JCPDS card. As the identified precipitated crystal seeds, MgO · SiO ₂ is “A”, BaO · 2MgO · 2SiO ₂ is “B”, 2SiO ₂ · 2ZnO · BaO is “C”, and La ₂ O ₃ · 2SiO ₂ is “D”. As shown in the table.

As is apparent from the table, No. 1 as an example of the present invention. Samples 1 to 9 had a large difference between the softening point and the crystallization temperature of 90 ° C. or more, and were excellent in fluidity during firing. Further, since the high expansion crystal was precipitated by the heat treatment, the thermal expansion coefficient was as high as 88 to 114 × 10 ⁻⁷ / ° C. Further, it can be seen that the melting point of the precipitated crystal is high and the heat resistance is also excellent. On the other hand, No. as a comparative example. Sample No. 10 had a small difference between the softening point and the crystallization temperature of 10 ° C., and was inferior in fluidity during firing. No. Since the sample No. 11 did not precipitate highly expanded crystals by heat treatment, the coefficient of thermal expansion is as low as 56 × 10 ⁻⁷ / ° C., and it is considered that the sample is inferior in heat resistance.

The crystalline glass composition of the present invention is suitable as an adhesive material for metals such as SUS and Fe, and high expansion ceramics such as ferrite and zirconia. In particular, it is suitable as an adhesive material for hermetically sealing a support substrate, an electrode member, and the like used when manufacturing an SOFC. Moreover, the crystalline glass composition of the present invention can be used for purposes such as coating and filling in addition to adhesive applications. Specifically, it can be used for applications such as thermistors and hybrid ICs.

1 Electrolyte 2 Anode 3 Cathode 4 First Support Substrate 4a Fuel Channel 4a
5 Second support substrate 5a Air channel 5a

Claims (7)

A crystalline glass composition comprising, in mol%, SiO ₂ + CaO 57 to 80%, MgO + BaO 0 to 40%, ZnO 10 to 40%, La ₂ O ₃ 0 to 15%. _2. The crystalline glass composition according to claim 1, which does not substantially contain R ₂ O (R represents an alkali metal) and P ₂ O ₅ . To claim 1 or 2, characterized in that to deposit at least one crystal selected from _{MgO · SiO 2, BaO · 2MgO} · 2SiO 2, 2SiO 2 · 2ZnO · BaO and _La 2 _O 3 · 2SiO ₂ by heat treatment The crystalline glass composition described. The crystalline glass composition according to any one of claims 1 to 3, wherein a thermal expansion coefficient in a temperature range of 30 to 950 ° C is 85 × 10 ^-7 / ° C or more. The crystalline glass composition according to any one of claims 1 to 4, wherein the difference between the softening point and the crystallization temperature is 85 ° C or more. 2. SiO ₂ 40 to 70%, MgO 5 to 40%, BaO 5 to 40%, ZnO 5 to 40%, CaO 3 to 30%, La ₂ O ₃ more than 0 to 15%, 6. The crystalline glass composition according to any one of items 5 to 5 . The crystalline glass composition according to any one of claims 1 to 6 , wherein the crystalline glass composition is used for adhesion.

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