JP2019034876A - Crystalline glass composition - Google Patents

Abstract

To provide a crystalline glass composition having high heat expansion coefficient after a heat treatment and even excellent in heat resistance after adhesion.SOLUTION: There is provided a crystalline glass composition depositing crystals of CaMgSiOand BaZnSiOby a heat treatment, in which an intensity ratio Y/X is over 0 to 1.6, where X is an X ray diffraction peak intensity of a (2 2 -1) crystal surface of the CaMgSiOand Y is the X ray diffraction peak intensity of a (2 1 1) crystal surface of the BaZnSiO.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a crystalline glass composition, and more specifically to a crystalline glass composition used for the purpose of bonding metals such as SUS and Fe, and high-expansion ceramics such as ferrite and 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 highest power generation efficiency among the fuel cells due to the low internal resistance of the cell, and 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 has been proposed in which an inorganic sheet-shaped gasket such as mica, vermiculite, or alumina is sandwiched and hermetically sealed, 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 1000 ° 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 an SOFC adhesive material, Patent Document 1 discloses a SiO ₂ —B ₂ O ₃ —SrO-based amorphous glass composition.

JP 2006-56769 A

  Since the amorphous glass composition disclosed in Patent Document 1 has a glass transition point of around 600 ° C., the bonded portion melts in a high-temperature operating environment such as about 600 to 1000 ° C., resulting in airtightness and adhesiveness. There is a problem that cannot be secured.

  In view of the above, an object of the present invention is to provide a crystalline glass composition having a high coefficient of thermal expansion 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-mentioned problems can be solved by a crystalline glass composition in which specific crystals are precipitated by heat treatment and the amount of crystals is strictly controlled. In the present invention, the “crystalline glass composition” refers to a glass composition having a property of precipitating crystals upon heat treatment. “Heat treatment” means heat treatment at a temperature of 800 ° C. or higher for 10 minutes or longer.

That is, the crystalline glass composition of the present invention is a crystalline glass composition in which CaMg ₂ Si ₂ O ₇ and BaZn ₂ Si ₂ O ₇ crystals are precipitated by heat treatment, and the CaMg ₂ Si ₂ O ₇ ( 2 2-1) When the X-ray diffraction peak intensity of the crystal plane is X and the X-ray diffraction peak intensity of the (2 1 1) crystal plane of BaZn ₂ Si ₂ O ₇ is Y, the intensity ratio Y / X is It is 0.1-1.6.

CaMg ₂ Si ₂ O ₇ and BaZn ₂ Si ₂ O ₇ is a high expansion crystal precipitated by heat treatment, _further, the _{CaMg 2 Si 2 O 7 (2} 2 -1) X -ray diffraction peak intensity X and BaZn crystal plane It was found that when the intensity ratio Y / X of the X-ray diffraction peak intensity Y of the (2 1 1) crystal plane of ₂ Si ₂ O ₇ is more than 0 to 1.6, it has a high thermal expansion coefficient. Further, since CaMg ₂ Si ₂ O ₇ and BaZn ₂ Si ₂ O ₇ have a high melting point, even when used at a high temperature for a long period of time, the bonded part is difficult to melt, and the air tightness and adhesiveness of the bonded part Can be suppressed.

  The reason why the intensity ratio Y / X is limited to more than 0 to 1.6 will be described below.

Since the thermal expansion coefficient of CaMg ₂ Si ₂ O ₇ is higher than the thermal expansion coefficient of BaZn ₂ Si ₂ O ₇ , if the amount of crystals of CaMg ₂ Si ₂ O ₇ is large, it is easy to obtain high expansion characteristics. The X-ray diffraction peak intensity X is proportional to the crystal amount of CaMg ₂ Si ₂ O ₇ , and the X-ray diffraction peak intensity Y is proportional to the crystal amount of BaZn ₂ Si ₂ O ₇ . That is, reducing the intensity ratio Y / X from over 0 to 1.6 leads to an increase in the amount of crystals of CaMg ₂ Si ₂ O ₇ , and as a result, high expansion characteristics can be achieved.

Crystallizable glass composition of the present invention, in _{mol%, SiO 2 35~70%, 4~20} % MgO, CaO 4~30%, BaO 4~20%, to contain 5 to 25% ZnO preferred .

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 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 850 ° C.

  The crystalline glass composition of the present invention is preferably in a powder form.

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

  The crystalline glass composition of the present invention has a high coefficient of thermal expansion after heat treatment and is excellent in heat resistance after bonding. 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 precipitates CaMg ₂ Si ₂ O ₇ and BaZn ₂ Si ₂ O ₇ crystals by heat treatment. Since CaMg ₂ Si ₂ O ₇ and BaZn ₂ Si ₂ O ₇ have a high melting point and are difficult to flow even when heat-treated again, heat resistance can be maintained over a long period of time. Further, X is the X-ray diffraction peak intensity of the (2 2 -1) crystal plane of CaMg ₂ Si ₂ O ₇ , and Y is the X-ray diffraction peak intensity of the (2 1 1) crystal plane of BaZn ₂ Si ₂ O ₇ . In this case, the strength ratio Y / X is more than 0 to 1.6, preferably 0.2 to 1.4, 0.5 to 1.3, particularly preferably 0.6 to 1.2. When Y / X is too large, it is difficult to obtain high expansion characteristics. Note that MgSiO ₃ , BaMg ₂ Si ₂ O _7, La ₂ Si ₂ O _7, etc., which are highly expanded crystals, may be precipitated by heat treatment.

The thermal expansion coefficient in the temperature range of 30 to 850 ° C. of the crystalline glass composition after the heat treatment is 85 × 10 ⁻⁷ / ° C. or higher, 90 × 10 ⁻⁷ / ° C. or higher, particularly 95 × 10 ⁻⁷ / ° C. or higher. Preferably there is. The upper limit is not particularly limited, but is practically 150 × 10 ⁻⁷ / ° C. or lower. Incidentally, the crystalline glass composition of the present invention tends to have a high crystallinity after heat treatment.

  Next, the glass composition of the crystalline glass composition of the present invention will be described.

Crystallizable glass composition of the present invention, in _{mol%, SiO 2 35~70%, 4~20} % MgO, CaO 4~30%, BaO 4~20%, to contain 5 to 25% ZnO preferred . The reason for limiting the glass composition as described above will be described below. In the following description regarding the content of each component, “%” means “mol%” unless otherwise specified.

SiO ₂ is a constituent component of highly expanded crystals CaMg ₂ Si ₂ O ₇ and BaZn ₂ Si ₂ O ₇ that are precipitated by heat treatment, and has an effect of improving water resistance. The content of SiO ₂ is 35 to 70%, preferably 40 to 65%, more preferably 45 to 62%, and particularly preferably 49 to 60%. When the content of SiO ₂ is too small, it becomes difficult for the highly expanded crystals CaMg ₂ Si ₂ O ₇ and BaZn ₂ Si ₂ O ₇ to precipitate during the heat treatment, and the heat resistance tends to decrease. Moreover, water resistance tends to decrease. On the other hand, if the content of SiO ₂ is too large, high-expansion crystallized CaMg ₂ Si ₂ O ₇ and BaZn ₂ Si ₂ O ₇ is less likely to precipitate during the heat treatment. In addition, the melting temperature tends to be high and melting tends to be difficult.

MgO is a constituent component of the highly expanded crystal CaMg ₂ Si ₂ O ₇ that is precipitated by heat treatment. The content of MgO is 4 to 20%, preferably 5 to 18%, more preferably 6 to 15%. If the content of MgO is too small, the highly expanded crystal CaMg ₂ Si ₂ O ₇ is difficult to precipitate during the heat treatment, and the heat resistance tends to decrease. On the other hand, when there is too much content of MgO, there exists a tendency for the vitrification range to become narrow and it becomes easy to devitrify. Moreover, fluidity tends to be lowered.

CaO is a constituent component of the highly expanded crystal CaMg ₂ Si ₂ O ₇ precipitated by heat treatment, and has an effect of improving fluidity. The content of CaO is 4 to 30%, preferably 5 to 28%, more preferably 6 to 20%. When the content of CaO is too small, high-expansion crystallized CaMg ₂ Si ₂ O ₇ is less likely to precipitate during the heat treatment, the heat resistance tends to lower. Moreover, fluidity tends to be lowered. On the other hand, when there is too much content of CaO, there exists a tendency for the vitrification range to become narrow and it becomes easy to devitrify. Moreover, fluidity tends to be lowered.

BaO is a constituent component of the highly expanded crystal BaZn ₂ Si ₂ O ₇ that is precipitated by heat treatment. The content of BaO is 4 to 20%, preferably 4 to 15%, more preferably 5 to 10%. When the content of BaO is too small, the highly expanded crystal BaZn ₂ Si ₂ O ₇ is difficult to precipitate during the heat treatment, and the heat resistance tends to decrease. On the other hand, when there is too much content of BaO, there exists a tendency for the vitrification range to become narrow and it becomes easy to devitrify. Moreover, fluidity tends to be lowered.

Incidentally, when the content of CaO is larger than the content of _BaO, easily achieving a high expansion characteristics increases the crystal volume of CaMg 2 _Si 2 _{O 7.}

ZnO is a constituent component of the highly expanded crystal BaZn ₂ Si ₂ O ₇ that is precipitated by heat treatment. The content of ZnO is 5 to 25%, preferably 7 to 20%, more preferably 8 to 18%, and particularly preferably 9 to 16%. When the content of ZnO is too small, it becomes difficult for the highly expanded crystal BaZn ₂ Si ₂ O ₇ to precipitate during heat treatment, and the heat resistance tends to be lowered. On the other hand, when there is too much content of ZnO, the vitrification range tends to become narrow, and devitrification tends to occur.

  In addition to the above components, the following various components can be contained.

TiO ₂ is a component that improves heat resistance. It is also a component that improves fluidity. The content of TiO ₂ is 0 to 5%, preferably 0.1 to 3%. It tends to be devitrified when melted and the content of TiO ₂ is too large. Moreover, fluidity tends to be lowered.

ZrO ₂ is a component that improves heat resistance. It is also a component that improves fluidity. The content of ZrO ₂ is 0 to 5%, preferably 0.1 to 3%, more preferably 1 to 2%. It tends to be devitrified when melted and the content of ZrO ₂ is too high. Moreover, fluidity tends to be lowered.

  SrO is a component that improves fluidity. The SrO content is 0 to 10%, preferably 0 to 5%. When there is too much content of SrO, there exists a tendency for the vitrification range to become narrow and it becomes easy to devitrify. Moreover, fluidity tends to be lowered.

B ₂ O ₃ is a component that improves fluidity. The content of B ₂ O ₃ is 0 to 5%, preferably 0 to 4%, more preferably 0 to 3%. If the B ₂ O ₃ content is too large, water resistance and heat resistance tends to decrease. Further, when used as an adhesive material for constituent members of a fuel cell, B ₂ O ₃ volatilizes when used at a high temperature, and the power generation characteristics tend to deteriorate.

Al ₂ O ₃ is a component that improves heat resistance. The content of Al ₂ O ₃ is 0 to 5%, preferably 0 to 3%. When the content of Al ₂ O ₃ is too large, heat treatment by 2SiO ₂ · _{Al 2 O} 3 · becomes low expansion crystal BaO or the like is likely to precipitate, hardly high expansion characteristics.

La ₂ O ₃ is a component for improving fluidity. Moreover, it is a component which expands the vitrification range and facilitates vitrification. The content of La ₂ O ₃ is 0 to 10%, preferably 1 to 8%, more preferably 2 to 7%, and particularly preferably 4 to 6%. When the content of La ₂ O ₃ is too large, easily devitrified when melted or during the heat treatment, the fluidity becomes difficult to obtain suitable adhesion.

The crystalline glass composition of the present invention contains 2% Y ₂ O ₃ , Gd ₂ O ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , SnO ₂ , WO ₃ , Bi ₂ O _3, etc. as components other than those described above. Can be contained. However, since R ₂ O (R represents an alkali metal) and P ₂ O ₅ are easily volatilized by heat treatment and may adversely affect the power generation characteristics such as reducing the electrical insulation properties of the SOFC component, It is preferable not to contain.

The crystalline glass composition of the present invention is prepared by adjusting magnesia (MgO), zinc white (ZnO), zirconia (ZrO ₂ ), titania (TiO ₂ ), alumina (Al ₂ O) in order to adjust fluidity and thermal expansion coefficient. _You may add and use powders, such as ₃ ), 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. In addition, 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 materials prepared to have the above composition are melted at 1400 to 1600 ° C. for about 0.5 to 2 hours until a homogeneous glass is obtained. Next, the molten glass is formed into a film or the like, and then pulverized and classified to produce a glass powder made of the crystalline glass composition of the present invention. In addition, it is preferable that the particle size (d50) of glass powder is about 2-20 micrometers. 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.

  The resin is a component that increases the film strength after drying and imparts flexibility, and the 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 dry 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 location 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 to fix the first and second members, and crystals precipitate. 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.

  Below, although the crystalline glass composition of this invention is demonstrated based on an Example, this invention is not limited to these Examples.

Tables 1 and 2 show examples of the present invention (sample Nos. 1 to 9, 11, 12) and comparative examples (sample No. 10).

  Each sample was produced as follows.

  The raw materials prepared so as to have the respective compositions in the table were melted at 1400 to 1600 ° C. for about 2 hours, 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 classified to obtain a sample (crystalline glass composition powder) having a particle size (d50) of about 10 μm.

For each sample, the X-ray diffraction peak intensity X of the (2 2 -1) crystal plane of CaMg ₂ Si ₂ O ₇ and the X-ray diffraction peak intensity Y, Y of the (2 1 1) crystal plane of BaZn ₂ Si ₂ O ₇ / X, thermal expansion coefficient, softening point, crystallization temperature, crystal melting point were measured or evaluated. The results are shown in Tables 1 and 2.

As is apparent from the table, Examples No. Samples of 1～9,11,12 _{is, CaMg 2 Si 2 O 7,} BaZn 2 Si 2 O 7 is precipitated by heat treatment, and, for Y / X was 0.7 to 1.3, the thermal expansion coefficient Was as high as 86 to 102 × 10 ⁻⁷ / ° C. Furthermore, it was found that the melting point of the precipitated crystal was high and the heat resistance was excellent.

On the other hand, No. which is a comparative example. Ten samples had a large Y / X of 1.9 and a low coefficient of thermal expansion of 83 × 10 ⁻⁷ / ° C.

  In addition, measurement and evaluation of each characteristic were performed as follows.

  X-ray diffraction peak intensities X and Y were measured using XRD. Thereafter, Y / X was calculated.

  The coefficient of thermal expansion is determined by JIS using a measurement sample obtained by press-molding each glass powder sample, heat-treating it at 1000-1100 ° C. for 3 hours, and polishing it into a cylindrical shape having a diameter of 4 mm and a length of 20 mm. Based on R3102, a value in a temperature range of 30 to 850 ° C. was obtained.

  The softening point, crystallization temperature, and crystal melting point were measured using a macro 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. Note that the higher the crystal melting point or if the crystal melting point is not confirmed, it means that the crystal exists stably even at a high temperature, and it can be determined that the heat resistance is high.

  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 in 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.

DESCRIPTION OF SYMBOLS 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 in which crystals of CaMg ₂ Si ₂ O ₇ and BaZn ₂ Si ₂ O ₇ are precipitated by heat treatment, and an X-ray diffraction peak of a (2 2 -1) crystal plane of CaMg ₂ Si ₂ O ₇ When the intensity is X and the X-ray diffraction peak intensity of the (2 1 1) crystal plane of BaZn ₂ Si ₂ O ₇ is Y, the intensity ratio Y / X is more than 0 to 1.6. A crystalline glass composition. In _{mol%, SiO 2 35~70%, 4~20} % MgO, CaO 4~30%, BaO 4~20%, crystallinity of claim 1, characterized in that it contains 5 to 25% ZnO Glass composition.   The crystalline glass composition according to claim 1 or 2, wherein the content of CaO is larger than the content of BaO. The crystalline glass composition according to any one of claims 1 to 3, which does not substantially contain R ₂ O (R represents an alkali metal) and P ₂ O ₅ . The crystalline glass composition according to any one of claims 1 to 4, wherein a thermal expansion coefficient in a temperature range of 30 to 850 ° C is 85 × 10 ^-7 / ° C or more.   The crystalline glass composition according to any one of claims 1 to 5, which is in a powder form.   The crystalline glass composition according to claim 1, wherein the crystalline glass composition is for bonding.