KR101457614B1 - Glass composition for solid oxide fuel cell sealant, sealant and the manufacturing method using the same - Google Patents

Abstract

The present invention relates to a glass composition for a solid oxide fuel cell sealant which comprises 55-62 mole% of SiO_2, 0-7 mole% of B_2O_3, 5-30 mole% of BaO+SrO, 1-15 mole% of ZnO and 1-3 mole% of Al_2O_3. In the glass composition, SiO_2/RO (R=Ba, Sr or Zn) is 1.5-2.0. (BaO+SrO)/ZnO is 2.0-3.0, wherein 5-30 mole% of BaO, 0-23 mole% of SrO and 0-20 mole% of ZnO are contained. The present invention relates to a solid oxide fuel cell sealant additionally comprising 40 wt% or less of ceramic or glass ceramic with a high temperature expansion coefficient of 120x10^-7/°C or more. The present invention is able to secure stability even in being used for long periods of time since the sealant and a solid oxide fuel cell stack have excellent glass stability, mobility and sealing adhesion at high temperatures when a sealant is manufactured by using the glass composition for the solid oxide fuel cell sealant.

Description

TECHNICAL FIELD The present invention relates to a glass composition for a solid oxide fuel cell sealing material, a sealing material using the glass composition, and a method for manufacturing the same. BACKGROUND ART [0002]

The present invention relates to a glass composition for a sealing material for a solid oxide fuel cell and a sealing material using the glass composition. More particularly, the present invention relates to a sealing composition comprising 55 to 62 mol% of SiO ₂ , 0 to 7 mol% of B ₂ O ₃ , (BaO + SrO) (R = Ba, Sr or Zn) of 1.5 to 2.0, (BaO + SrO) ₂ , and more preferably 1 to 30 mol% of ZnO, 1 to 15 mol% of ZnO and 1 to 3 mol% of Al ₂ O ₃ , / ZnO in the range of 2.0 to 3.0, 5 to 30 mol% of BaO, 0 to 23 mol% of SrO and 0 to 20 mol% of ZnO.

The solid oxide fuel cell stack is generally divided into a single cell composed of an electrolyte, a cathode and an anode, a connecting material connecting the unit cell and the unit cell, and a sealing material sealing the connecting material and the unit cell. In the case of the planar stack, unlike the cylindrical stack, the gas flow between the anode and the cathode or between the anode and the cathode during operation of the fuel cell differs slightly depending on the structure of the cell. It is essential to develop a sealing glass as a sealing material for bonding the constituent layers and supporting the entire stack. Since the sealing material must support the entire stack, it must not be deformed under high temperature and pressure, and should have both high temperature fluidity and high temperature strength so as to alleviate the thermal stress due to the difference in thermal expansion coefficient. In addition, in order to minimize the thermal stress generated during operation of the battery, the thermal expansion coefficient should be matched with the constituent layers of the battery, and the airtightness due to excellent bonding property and the chemical stability against the oxidizing and reducing atmosphere gas are required. (2 ㏀ · cm 2 or more), and it is possible to make contact with an electrode having a porous microstructure. Therefore, physical properties should be controlled so as to prevent penetration into micropores due to capillary phenomenon during contact. That is, the milk engraved upon confidential adhesive sealing material and the target bonding material shall be greater than 90 °, the viscosity of the sealing material is manufactured temperature (850 ~ 1000 ℃) 10 at ⁵ Pa · s, 10 ⁹ Pa at the operating temperature (650 ~ 850 ℃) · S or less.

The solid oxide fuel cell, a high temperature glass sealing material is _{SrO-La 2 O 3 -Al 2} O 3 -B 2 O 3 -SiO 2 and _{BaO-Al 2 O 3 -B 2} O 3 -As 2 O 3 and CaO in the glass composition, etc. -Al ₂ O ₃ -SiO ₂ has already been known, but it lacks structural stability such as cracking, surface desorption, pore formation, and interlayer formation during long-term use, and has a problem of surface reaction, vaporization, separation, Chemical stability is also known to be problematic.

In addition, a sealing material for a conventional solid oxide fuel cell is rapidly crystallized during sealing and causes cracks and leaks. In order to prevent this, a sealing material having an excellent glass stability is required because crystallization is suppressed to the maximum at a high temperature sealing temperature .

Also, most of the separators used in manufacturing solid oxide fuel cell stacks use metal with high thermal expansion coefficient. Therefore, the sealing material which must maintain airtightness between the separator plate and the unit cells must consider the stability of the stack in actual operation For this purpose, the thermal expansion coefficient of the solid oxide fuel cell should have a value of at least 100 × 10 ^-7 / ° C. so that it is necessary for airtight adhesion with electrodes and connecting members, and minimization of thermal stress due to temperature changes.

The research to manufacture the sealing glass conforming to these various conditions has continued to be active with the development of the SOFC. The airtight adhesive used in the SOFC must be airtightly bonded to the adherend primarily, and the above-mentioned properties such as thermal expansion coefficient and heat resistance must be satisfied.

In the early stage of solid oxide fuel cell development, soda-lime silicates, alkali silicates, alkaline-earth silicates, and alkali borosilicate glasses were used as sealants. However, these glasses react with the components of the battery or have a viscosity of less than 10 ³ Pa · s at 800-1000 ° C., which causes a problem of leakage of the tightly sealed adhesive. The borosilicate glass such as pyrex has a thermal expansion coefficient of 3.210 ^{- 6} / 캜, which is significantly smaller than that of the SOFC component, resulting in thermal stress.

In addition, most of the compositions developed have been used for a long time in the operating temperature and atmosphere of the solid oxide fuel cell, or as the cycle progresses, the crystallization progresses, resulting in structural stability such as cracking, surface desorption, pore formation, And the sealing efficiency can not exceed 80%.

Further, in order to have a high thermal expansion coefficient, some metals are mixed and sealed, but in this case, there is a problem that the metal expands, and it is difficult to maintain electrical insulation and is not stable in an actual working atmosphere.

In addition, there is a case where the metal separator is sealed between the metal separator and the unit cell in the form of a mica. However, in this case, leakage is easily generated due to difficulty in hermetic sealing and has a weak heat cycle.

SUMMARY OF THE INVENTION The present invention has been conceived to solve the above-mentioned problems, and an object of the present invention is to provide a sealing material which is excellent in sealing performance and is free from structural problems such as cracks, pores, A glass composition for a solid oxide fuel cell which maintains high reliability even when using SOFC for a long time, and a sealing material for a solid oxide fuel cell having a high thermal expansion coefficient produced by using the glass composition.

The present invention to achieve the above object, SiO ₂ 55 ~ 62 _{mol%, B 2 O 3 0 ~} 7 mol%, (BaO + SrO) 5 ~ 30 mol%, ZnO 1 ~ 15 mol%, Al ₂ O ₃ contains from 1 to 3 _{mol%, SiO 2 / RO (R} = Ba, Sr or Zn) is 1.5 ~ 2.0, and, (BaO + SrO) / ZnO is a 2.0 ~ 3.0 BaO 5 ~ 30 mol%, SrO 0 To 23 mol%, and ZnO in an amount of 0 to 20 mol% based on the total weight of the solid oxide fuel cell encapsulant.

When the sealing material is produced using the glass composition for a sealing material, it is preferable that the firing temperature does not exceed 1000 占 폚, and the operating temperature after applying the sealing material does not exceed 850 占 폚.

It is preferable that the glass composition further comprises any one selected from Y ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , WO ₃ , GeO ₂ , and La ₂ O ₃ , or a combination thereof.

It is preferable that any one or a combination thereof selected from the group consisting of Y ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , WO ₃ , GeO ₂ and La ₂ O ₃ is added in an amount of more than 0 to 10 wt% desirable.

It is preferable that the glass composition further includes a ceramic or glass ceramic exhibiting a thermal expansion coefficient of at least 120 x 10 < ^-7 > / DEG C or less.

The ceramic showing the thermal expansion coefficient of at least 120 × 10 ^-7 / ℃ or glass ceramic is MgO, SrO, KAlSiO _4, YSZ (Yittria stabilized Zirconia), cristobalite, SiO ₂ type glass, and comprising a ceramic, more than 0 to 40, based on the weight of the composition It is preferably added in the range of within the range of% by weight.

Also, the present invention provides a solid oxide fuel cell sealing material, which is produced using the above composition.

The sealing material is preferably produced by laminating a plurality of sheets.

Also, the present invention provides a paste for a solid oxide fuel cell sealing material, which is produced by adding a solvent to the composition.

The present invention also relates to a method for producing a glass composition, Milling the prepared glass and spray drying to produce granulated glass; And a step of preparing the granulated glass as a sealing material by using a mold. In the step of manufacturing the sealing material, the granulated glass is manufactured by heat treatment at a temperature higher than its softening point, A method of manufacturing a battery sealing material is provided.

The temperature higher than the softening point is preferably 5 to 40 ° C higher than the softening point.

The heat treatment time is preferably 0.5 to 4 hours.

According to the invention as described above, for a long time when used in SOFC the progress of the crystallization of the less tight adhesion is maintained, and an oxide ceramic or a glass ceramic with at least 120 × 10 ^-7 / ℃ high thermal expansion coefficient, such as cristobalite (cristobalite) It is expected that the effect of improving the durability and reliability of the unit cell stack by preventing the breakage phenomenon caused by the difference in the thermal expansion coefficient between the respective components of the conventional stack by adding the thermal expansion coefficient.

Further, by using insulation properties of a sealing sheet or a sealing paste made of glass or a glass ceramic material, it is possible to more widely select the material of the support, for example, by allowing the support to be made of metal by inducing insulating action between a connecting member, And the like.

In the present invention, a sealing material is prepared using a glass composition containing no alkali oxide. When a glass material containing alkali oxide is used, it is easy to manufacture and can easily produce glass, but resistance to high temperature and rapid temperature change is low. Therefore, it is advantageous not to include an alkali oxide when it is to be used at a high temperature such as a solid oxide fuel cell.

FIG. 1 and FIG. 2 are graphs showing the results of X-ray analysis of the glass composition according to an embodiment of the present invention at various holding times at 750.degree.
3 is a graph showing the thermal expansion of a glass composition prepared by mixing 15% by weight of cristobalite with 30% by weight of La ₂ O ₃ , B ₂ O ₃ and SrO in a glass composition according to an embodiment of the present invention. Fig.
4 is a schematic view showing an example in which a sealing material manufactured according to an embodiment of the present invention is applied between stainless steel and a negative electrode material, which is a metal separator.
FIG. 5 is a SEM photograph taken to maintain the sealing material applied by FIG. 4 at 750 ° C. for 100 hours and to observe the microstructure before and after the holding.
6 is a photograph showing a gasket of a sheet-like rectangular shape as a sealing material made of a glass composition according to an embodiment of the present invention.
7 is a photograph showing a sheet-like circular ring-shaped gasket as a sealing material made of a glass composition according to an embodiment of the present invention.
8 is a photograph showing a square gasket as a sealing material produced in a mass production system.
9 is a photograph showing a circular ring gasket as a sealing material produced in a mass production system.

Hereinafter, the present invention will be described in more detail based on the accompanying drawings and preferred embodiments.

The present invention is characterized in that the physical properties of the glass composition for a sealing material are improved, that the sealing material is improved by preparing the sealing material using such a composition, and that the high temperature strength of the support is reinforced.

The present invention includes 55 to 62 mol% of SiO ₂ , 0 to 7 mol% of B ₂ O ₃ , 5 to 30 mol% of (BaO + SrO), 1 to 15 mol% of ZnO and 1 to 3 mol% of Al ₂ O ₃ and, SiO ₂ / RO a (R = Ba, Sr or Zn) is 1.5 ~ 2.0, (BaO + SrO ) / ZnO is a 2.0 ~ 3.0 BaO 5-30% by mole, SrO 0-23% by mole, ZnO 0- 20 mol%, based on the total weight of the solid oxide fuel cell sealing material.

If the content of SiO ₂ is less than 55 mol%, glass formation is difficult and crystallization easily occurs. If the content of SiO ₂ is more than 62 mol%, the glass structure is strong and the flow does not easily occur at the sealing temperature. B ₂ O ₃ may or may not be contained, and it is preferably not more than 7 mol%. When it exceeds 7 mol%, the glass is phase-separated or crystallized. (BaO + SrO), if the content is less than 5 mol%, the flow easily occurs at a low temperature and is not usable at the operating temperature of the solid oxide fuel cell, and when it is more than 30 mol%, crystallization occurs. When the content of ZnO is less than 1 mol%, the flowability is insufficient. When the content of ZnO is more than 15 mol%, flow occurs easily at a low temperature. When the content of Al ₂ O ₃ is less than 1 mol%, the stability of the glass is deteriorated, and when it is more than 3 mol%, crystallization of the glass is caused. When SiO ₂ / RO is less than 1.5 in the above SiO ₂ / RO (R = Ba, Sr or Zn), the glass is not melted or crystallized easily. If the SiO ₂ / RO is 2.0 or more, no flow occurs or crystallization occurs at the sealing temperature . It is more preferably 2.0 to 2.5 in (BaO + SrO) / ZnO. When (BaO + SrO) / ZnO is 2.0 or less, the glass is not formed well, and when it is 3.0 or more, the flow does not occur easily.

≪ Example 1 >

In the present invention, 0 to 31 mol% of La ₂ O ₃ , B ₂ O ₃ and SrO are added to a SiO ₂ -BaO-ZnO-Al ₂ O ₃ system as a raw material composition in order to produce a high temperature glass sealing material for a solid oxide fuel cell A glass composition for a sealing material was prepared in the composition shown in Table 1. Here, a mixture of La ₂ O ₃ instead of _{Y 2 O 3, Ga 2 O} 3, In 2 O 3, WO 3, GeO 2, at least can also be further added to any one selected from the group consisting of and, in which La ₂ O ₃ It is an embodiment. On the other hand, any one selected from Y ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , WO ₃ , GeO ₂ , and La ₂ O ₃ or a combination thereof may be contained in an amount of 10 mol% These are included for the purpose of increasing the coefficient of thermal expansion of the glass. If it is added in an amount of more than 10 mol%, crystallization of the glass may be caused and the thermal expansion coefficient may be lowered.

However, La ₂ O ₃ and the like are optional elements, and the feature of the present invention is satisfied even if it is excluded.

Unit: mol% Sample number One 2 3 4 5 6 7 Furtherance SiO2 57 59 59 59 59 59 59 B2O3 7 5 0 5 0 0 0 BaO 23 23 28 5.5 10.5 5.5 13 ZnO 10 10 10 10 10 10 10 Al2O3 2 3 3 3 3 3 3 La2O3 0 0 0 0 0 0 2.5 SrO 0 0 0 17.5 17.5 22.5 12.5 Total 100 100 100 100 100 100 100 (BaO + SrO) / ZnO 2.3 2.3 2.8 2.3 2.8 2.8 2.0 SiO2 / RO 1.7 1.8 1.6 1.8 1.6 1.6 1.6 Thermal properties Tg () 664 665 716 668 714 716 712 CTE (x10 ^-7) 85.8 67.2 75.8 70.2 74.8 75.5 74.1

To prepare a glass composition for a sealing material, each element weighed to the first decimal point was placed in a Teflon pot, mixed with an alumina ball for 4 hours by dry method, and powder was placed in the mold to uniaxial pressurization . The molded mixed powder is melted in a platinum crucible at 1450 to 1500 ° C using a continuous melting furnace, and the melt is coarsely crushed together with glass, alumina balls and ethanol, and is jet-milled to a thickness of 2 to 5 μm By weight.

The prepared powder had a bulk density of 0.61 g / cc, a tap density of 1.19 g / cc, a flowability of 19, and a floodability of 23, It was confirmed that it was a powder suitable for use as a glass sealant and exhibited a thermal expansion coefficient of 70.2 to 85.8 × 10 ^-7 ppm / ° C. at 600 ° C. and a transition temperature of 664 to 716 ° C., a temperature suitable for use as a solid oxide fuel cell 600 ~ 1000 ℃. In addition, a high-temperature stable glass sealing material in which crystals are not generated in a practical application atmosphere and in a state where a high temperature is maintained for a long period of time can be produced.

At this time, a preferable firing temperature for producing the sealing material from the glass composition is not more than 1000 占 폚, and when the prepared sealing material is used, the operating temperature of the stack preferably does not exceed 850 占 폚.

When the firing temperature exceeds 1000 ° C., the sealing temperature should be higher than that in actual solid oxide fuel cells. Since the sealing temperature of 1000 ° C. or more is difficult to withstand other components of the solid oxide fuel cell, the firing temperature must not exceed 1000 ° C. Should not. In addition, when the operating temperature of the stack exceeds 850 ° C, the solid oxide sealing material, which must be used for several tens of thousands of hours, may not be softened or may have problems such as crystallization progression, so it should not exceed 850 ° C.

  FIG. 1 and FIG. 2 show X-ray analysis of each of the glass compositions after holding at different temperatures at 750 ° C. in the oxidation and reduction atmosphere using sample No. 1. As shown, no crystal phase was formed even after long-term maintenance.

≪ Example 2 >

In the present invention, in order to produce a high-temperature glass sealing material for a solid oxide fuel cell, 0 to 31 mol% of La ₂ O ₃ , B ₂ O ₃ and SrO are added to the SiO ₂ -BaO-ZnO-Al ₂ O ₃ system as a raw material composition The resulting glass composition was mixed with 15 parts by weight of cristobalite to prepare a glass composition for a crystal phase oxide mixed sealing material.

The cristobalite may be mixed in an amount of preferably 0 to 40% by weight, more preferably 10 to 40% by weight. Here, when it is 40 wt% or more, it is impossible to produce a rigid gasket.

Examples of other high thermal expansion coefficient materials other than cristobalite include MgO, SrO, KAlSiO ₄ , YSZ (Yittria stabilized zirconia), and SiO ₂ -based glass ceramics. They can replace cristobalite and have a thermal expansion coefficient of at least 120 × 10 ^-7 / ° C.

Of the glass compositions thus prepared, 15% by weight of cristobalite and 30% by weight of La ₂ O ₃ , B ₂ O ₃ and SrO were added to the glass component and mixed with zirconia balls having a diameter of 10 mm for 2 hours The thermal expansion coefficient of the glass composition was measured and shown in FIG. As shown in the drawing, the sealing material was produced using the glass composition according to Example 2 of the present invention and showed a thermal expansion coefficient of 100 × 10 ^-7 / ° C or higher.

As shown in FIG. 4, the sealing material prepared according to the present invention was sealed between stainless steel, which is a metal separator, and an anode material, and was then held at 750 ° C. for 100 hours to observe structural changes before and after the holding 5, respectively. As shown in the figure, the interface between the sealing material and the electrode has the same structure as that at the time of bonding, so that no defect is generated.

≪ Example 3 >

In this embodiment, a gasket for a sheet-type solid oxide fuel cell is manufactured by applying a sealing material prepared using the glass composition of Examples 1 and 2. [

In order to produce a sheet-shaped rectangular gasket, the oxide mixed glass powder according to the present invention was mixed using a zirconia ball having a diameter of 10 mm. The mixed powders were mixed in a Teflon pot at a ratio of 0.67: 1 based on the weight ratio of vehicle and mixed powder, and mixed with zirconia balls for 24 hours to prepare a slurry. The prepared slurry was formed into a sheet using a doctor blade. The sheet having a thickness of 0.4 mm or more was laminated to a desired thickness using a laminator at 50 to 80 ° C for 5 to 30 minutes, A square gasket was made. The fabricated gasket is shown in Fig.

In addition, a sheet type circular ring gasket was produced by using a slurry such as a sheet type square gasket and a circular ring gasket suitable under the same conditions. The gasket thus manufactured is shown in Fig.

The gasket manufactured by such a process has a high sealing efficiency and can be accurately sized with a single cell and a separator plate, and can be easily manufactured in a desired shape suitable for a single cell. Further, it is possible to easily manufacture a gasket having a high dimensional accuracy, to solve problems such as mixing of fuel and air, leakage of fuel to the outside, and low output.

That is, as a result of multilayer lamination of sheets, excellent sealing gaskets free from twisting and warpage could be produced.

<Example 4>

Example 4 is intended to confirm whether the intended properties were manifested when the sealing gasket was actually applied to the SOFC.

A manufacturing method of the sealed square gasket according to this embodiment is as follows.

The method for producing a sealing material according to the present invention comprises the steps of melting a glass composition to prepare glass, grinding the glass thus produced, spray drying the granulated glass to form a granulated glass, As a sealing material.

At this time, in the step of making the sealing material, the granulated glass is preferably manufactured by heat treatment at a temperature higher than the softening point by 5 to 40 ° C.

When a molded body is formed by press molding using granulated powder and heat-treated, it is said that it is hard and strong in the same concept as a kind of sintering, and forms glass particles and particles without pores therein. In order to heat the glass in such a sintering state, the glass is heated to a temperature higher than the softening point, ie, about 5 to 40 ° C, so that the glass surface is softened to attach the particles and particles. When the temperature is higher than 40 ° C, the glass spreads and can not hold the sintered body having the shape and becomes a molten glass lump. If the temperature is lower than 5 ° C, the molding itself can not be performed.

Meanwhile, since the heat treatment time as well as the heat treatment temperature are important, the heat treatment time is preferably 0.5 to 4 hours. If the heat treatment time is shorter than 0.5 hour, a hard sintered body can not be formed. If the heat treatment time exceeds 4 hours, the sintered state can not be maintained and melted glass lumps are formed, so that the above time range has a critical significance.

The following manufacturing process is one embodiment of the above process, and a sealed square gasket as shown in Fig. 6 as a sealing material for a solid oxide fuel cell is manufactured through the following process.

First, some La ₂ O ₃ , B ₂ O ₃ , and SrO were added to the CaO-Al ₂ O ₃ -B ₂ O ₃ -SiO ₂ system and the SiO ₂ -BaO-SrO-ZnO system, and at 1550 ° C., . Thereafter, the massive frit was wet pulverized to have a particle size of 5 to 10 mu m, and then dried. Cristobalite was added to the dried powder in a range of 0 to 31 wt%, and the mixture was mixed for 2 hours using a zirconia ball having a diameter of 10 mm while varying the addition amount. A binder, a dispersant, a plasticizer and the like were mixed with water and spray-dried to prepare a mixture of granules having a size of 80 to 120 탆.

When the spray dried spherical granules were vitrified, a 20% shrinkage occurred. Therefore, a mold for stacking was prepared. The mold was filled with granules, and in the case of a quadrangle, compression molding was performed at a pressure of 200 kg / cm 2 to form a quadrangular prism in a range of 80 to 200 mm. The molded article was held at a temperature 5 to 20 ° C higher than the softening point of the high-temperature glass sealant for 4 hours to produce a rectangular gasket.

Thereafter, the thus formed stacked square article of the stack was cut into a desired size of a rectangular gasket. The cut moldings were connected in the form of a rectangular gasket, and glass paste of the same composition was applied to each corner, heated to a temperature of 10 to 50 ° C higher than the sealing material, maintained for 4 hours, and then cooled to room temperature at a maximum holding temperature to produce a sealed square gasket . The gasket is shown in Fig.

As a result of long - term durability tests, the gaskets produced showed very high sealing efficiency of 90% without causing cracks or gas leakage. There was also a simple advantage in sealing the stack over existing sheets or pastes.

That is, in the case of existing sheets or pastes, it is necessary to add a binder burnout process, which is necessarily added in the sealing process when stacking the solid oxide fuel cell, or slow down the temperature raising rate. In the case of the sealed square gasket, The binder can be completely burnt out, so that the sealing process in the stacking of the solid oxide fuel cell can be carried out quickly and simply without burnout process.

&Lt; Example 5 >

A circular ring gasket for a solid oxide fuel cell as shown in Fig. 7 is used for hole sealing of a separator plate or the like. The production of the ring gasket is similar during the manufacture of the rectangular gasket and before the final heat treatment. Granular glass powder was prepared and a mold was made so that the final ring gasket had an outer diameter of 10 to 50 mm, an inner diameter of 4 to 46 mm and a thickness of 5 to 6 mm, granules were put in the mold, And then heat-treated at a temperature higher than the softening point of the high-temperature glass sealing material by 520 DEG C for 4 hours. Thereafter, the ring-shaped gasket was manufactured by cooling from the maximum holding temperature to room temperature. The produced ring gasket is shown in Fig.

As a result of the long-term durability test using the ring gasket, it was confirmed that no cracks or leakage of gas occurred.

Although specific embodiments of the invention have been described above, it will be obvious that the same may be varied in many ways by those skilled in the art. Such modified embodiments should not be understood individually from the technical idea or viewpoint of the present invention, and these modified embodiments should be included in the claims of the present invention.

Claims (12)

delete delete delete delete delete delete delete delete delete (1), wherein the composition contains 55 to 62 mol% of SiO ₂ , 0 to 7 mol% of B ₂ O ₃ , 12.5 to 30 mol% of (BaO + SrO), 1 to 15 mol% of ZnO and 1 to 3 mol% of Al ₂ O ₃ , based on the _{SiO 2 / RO (R = Ba} , Sr and Zn) is 1.5 ~ 2.0, and, (BaO + SrO) / ZnO is 2.0 to 3.0, the glass composition BaO 5-30 mol%, SrO 0-23% mol Melting glass to produce glass;
Milling the prepared glass and spray drying to produce granulated glass;
Preparing the granulated glass as a sealing material by using a mold;
, &Lt; / RTI &
Wherein the granulated glass is heat-treated at a temperature higher than its softening point in the step of producing the sealing material. 11. The method of claim 10,
Wherein the temperature higher than the softening point is a temperature higher by 5 to 40 ° C than the softening point. 11. The method of claim 10,
Wherein the heat treatment time is 0.5 to 4 hours. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt;

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