JP2019104672A - Glass - Google Patents

Abstract

To provide a glass containing not a large amount of ZnO and BO, suitable for sealing application as no inflection point (flexure) is seen in a thermal expansion curve of a burned body of a powder thereof, and adding high credibility to a resulting sealed article.SOLUTION: There is provided a glass containing practically no alkali metal oxide or BaO, and by mol% in terms of oxide, SiOof 40 to 44%, MgO of 15 to 23%, CaO of 28 to 36%, AlOof 5 to 10% with total content of these components of 97% or more and a molar ratio of contents of CaO and MgO represented by CaO/MgO of 1.2 to 2.3.SELECTED DRAWING: None

Description

The present invention is a glass paste suitable for sealing, bonding, etc. members selected from a group of members consisting of a SiO ₂ -MgO-CaO-Al ₂ O ₃ based glass, particularly a member containing metal or ceramic containing the glass, The present invention relates to a green sheet, a solid oxide fuel cell (hereinafter also referred to as SOFC), and a method for producing the same.

  In the production of a composite having a metal member or a ceramic member as a component, sealing glass is widely used as a bonding / sealing material for bonding / sealing these members into a composite. This sealing glass is typically used as a glass frit processed into powder, a glass paste obtained by pasting this glass frit, a green sheet (glass sheet) made from this glass frit into a sheet, and the like. That is, it is often used as a glass paste when bonding planar parts, or as a glass frit when bonding three-dimensional parts as a green sheet.

In recent years, a sealing glass that can be used to seal a member of SOFC having an operating temperature range of 700 to 1000 ° C. is required. As such SOFC sealing glass, for example, Patent Document 1 discloses B ₂ Glass which does not contain much O ₃ and which does not have an inflection point (flexure) in the thermal expansion curve of the sintered body of the powder, specifically 35 to 41.5 SiO _{2 in} mol% %, 8-25% MgO, more than 27% CaO, 35% or less, SrO 0-2%, BaO 0-4%, ZnO 5-15%, Al ₂ O ₃ 4.5-10% SiO ₂ -MgO-CaO-ZnO-Al of the composition such that the total content of these components is 97% or more, and the total content of these components is 2% or less when SrO and BaO are contained ₂ O ₃ based lead-free glass is disclosed .

Patent No. 5365517 gazette

  In Patent Document 1, the obtained lead-free glass powder is crystallized to become crystallized glass when fired, and no inflection point is found in the thermal expansion curve thereof, which is considered to be suitable as a SOFC sealing material. However, this lead-free glass contains 5% or more of ZnO. Since ZnO is prone to oxygen defects and crystal defects and the like due to oxygen defects, it has been a problem that a highly reliable seal can not be obtained when this lead-free glass is used as a seal material.

In Patent Document 1, when the content of ZnO is less than 5%, the glass becomes unstable and does not contain ZnO and B ₂ O ₃ , or the thermal expansion curve of the sintered body of the powder which is a glass not containing many. No sealing glass was obtained so that no inflection point (flexion) was seen in the

The present invention is a glass that does not contain ZnO and B ₂ O ₃ or does not contain many B ₂ O ₃ and is suitable for sealing applications in which no inflection point (flexure) is found in the thermal expansion curve of the sintered body of the powder. It is an object of the present invention to provide a glass which can impart high reliability to the obtained sealed product, a glass paste using the glass, a green sheet, a solid oxide fuel cell and a method for producing the same.

The present invention is substantially free of alkali metal oxides and BaO, and represents 40 to 44% of SiO ₂ , 15 to 23% of MgO, 28 to 36% of CaO, and Al on a mole% basis on oxide basis. the ₂ O ₃ containing 5-10%, and the total content of these components is 97% or more, the molar ratio of the content of CaO and MgO represented by CaO / MgO is in 1.2-2.3 Provided is a certain glass (hereinafter referred to as "first glass").

In addition, it contains substantially no alkali metal oxide and BaO, and represents 34 to 40% of SiO ₂ , 14 to 20% of MgO, 28 to 36% of CaO, and Al ₂ O in terms of mol% on an oxide basis. Glass containing 12 to 18% of ₃ and having a total content of these components of 97% or more and a molar ratio of the content of CaO to MgO represented by CaO / MgO of 1.5 to 2.5 (Hereafter, referred to as "second glass").

Moreover, it does not contain an alkali metal oxide and TiO ₂ substantially, and is 42 to 47% of SiO ₂ , 14 to 19% of MgO, 29 to 36% of CaO, Al ₂ in terms of mol% of oxide standard It contains ₃ to 7.5% of O ₃ , 0.3 to 5.5% of BaO, and 0 to 0.5% of SrO, and the total content of these components is 97% or more, CaO / MgO And a glass having a molar ratio of the content of CaO to MgO of 2.0 to 2.3 (hereinafter referred to as "third glass").

Furthermore, it contains substantially no alkali metal oxide and TiO ₂ , and represents 41 to 47% of SiO ₂ , 12.5 to 17.5% of MgO, and 26 to 36 of CaO in terms of mol% on an oxide basis. %, Al ₂ O ₃ more than 7.5% and 14% or less, BaO 0.3 to 4%, the total content of these components is 97% or more, and CaO and CaO represented by CaO / MgO Provided is a glass (hereinafter referred to as "fourth glass") in which the molar ratio of the content of MgO is 1.75 to 2.25.
There is also provided a glass paste containing a powder of a first, second, third or fourth glass.
Also provided is a green sheet containing a powder of the first, second, third or fourth glass.

  A method of manufacturing a solid oxide fuel cell, comprising the step of sealing members made of ceramics or metal to each other, wherein the members are made of the first, second, third or fourth glass powder. The present invention provides a method of manufacturing a solid oxide fuel cell sealed together.

  The solid oxide fuel cell according to the present invention is a solid oxide fuel cell having at least one sealing portion in which members made of ceramic or metal are sealed to each other, wherein at least one of the sealing portions is a first, a second and a third. Or a solid oxide fuel cell sealed with a fired body obtained by firing a powder of a fourth glass.

  In the present invention, “sealing members made of ceramics or metal to each other” includes the case where members made of ceramics and members made of metal are sealed to each other.

According to the present invention, a sintered body of a powder which does not contain ZnO or B ₂ O ₃ , or does not contain much, specifically does not contain more than 3 mol% in total of these. A glass is obtained in which no point of inflection is found in the thermal expansion curve of or substantially no point of inflection is found. The glass, glass paste and green sheet of the present invention are suitable for sealing application, particularly for sealing, joining, etc. of members selected from a group of members consisting of metal or ceramic, and the resulting sealed article has high reliability. It can be granted. According to the method for producing a solid oxide fuel cell of the present invention, it is possible to provide a highly reliable solid oxide fuel cell by using the glass.

  The present invention provides a first glass, a second glass, a third glass, and a fourth glass having the above-described compositions. As used herein, the "glass of the present invention" includes the first glass, the second glass, the third glass, and the fourth glass.

  The glass of the present invention is usually used in powder form. The glass of the present invention or its powder is typically used for sealing, in which case it is fired at, for example, 900-1100 ° C., typically 900-1000 ° C. to form a fired body, and the fired body is a crystallized glass is there.

Typical crystals precipitated in the crystallized glass, diopside _{(CaO-MgO-2SiO 2)} , akermanite _{(2CaO-MgO-2SiO 2)} , CaO-MgO-SiO 2 based crystal such melilite, forsterite, etc. High expansion crystals such as MgO-SiO ₂ -based crystals, CaO-SiO ₂ -based crystals, SiO ₂ -MgO-CaO-Al ₂ O ₃ -based crystals, and CaO-SiO ₂ -Al ₂ O ₃ -based crystals. Among them, the glass on which CaO-MgO-SiO ₂ system crystals such as diopsite, akermanite and melilite are precipitated at the time of firing has less transformation of the crystal phase at the time of firing and the strength of the bulk body (crystallized glass) after crystallization It tends to be stabilized and is preferred.

  Hereinafter, although the case where the glass of this invention is used for sealing of a SOFC structural member etc. is demonstrated to an example, the use of the glass of this invention is not limited to this. That is, the glass of the present invention is suitable for applications where it is required that no inflection point be observed or substantially no inflection point be observed in the thermal expansion curve of the sintered body of the powder.

The softening point (Ts) of the glass of the present invention is preferably 820 ° C. or more. If Ts is less than 820 ° C., the reaction with the member to be sealed may be too large, more preferably more than 820 ° C., typically 830 ° C. or more. Moreover, it is preferable that Ts is 920 degrees C or less. If Ts exceeds 920 ° C., the fluidity of the glass may be reduced.
The crystallization temperature (Tc) of the glass of the present invention is typically from 960 to 1050 ° C.

  Ts is subjected to differential thermal analysis to read a fourth inflection point, which is taken as Ts. Also, Tc is measured as follows. That is, a differential thermal analysis is performed to read the temperature of the exothermic peak that is found first (at the lowest temperature) on the high temperature side of Ts, and this is taken as Tc.

  (Tc-Ts) is preferably 110 ° C. or more. If (Tc-Ts) is less than 110 ° C., the fluidity at the time of firing may be insufficient, and a gap may be formed between the fired body (crystallized glass) and the object to be sealed, for example. is there. (Tc-Ts) is more preferably 120 ° C. or more, still more preferably 130 ° C. or more, particularly preferably 140 ° C. or more.

The average linear expansion coefficient (α) at 50 to 950 ° C. of the sintered body (crystallized glass) obtained by firing the powder of the glass of the present invention at 950 ° C. for 1 hour is 84 × 10 ^{−7 to} 105 × It is preferably 10 ⁻⁷ / ° C. If α is out of this range, the matching of the expansion coefficient with the sealed object may be insufficient.

  In the case of alpha measurement of the above-mentioned calcination object, the thermal expansion curve in 50-950 ° C of the calcination object is measured. The temperature rising rate in the α measurement is, for example, 10 ° C./min. The glass of the present invention preferably has a linear thermal expansion curve. The linear thermal expansion curve means that the differential peak in the differential curve of the thermal expansion curve determined by the following method is 0.01 μm / sec or less.

  First, differential curves (horizontal axis: temperature, vertical axis: change in length of sintered body per unit temperature) are created for the thermal expansion curve obtained above. If there is an inflection point in the thermal expansion curve, a peak or valley, usually a peak, will occur at the temperature corresponding to that inflection point of the derivative curve. If peaks or valleys exist in the derivative curve, the largest one of the height or the depth of the peaks is read. A differential peak of, for example, 1 μm / sec corresponds to a peak height or valley depth of 6 μm / ° C. In addition, when reading the height of a mountain or the depth of a valley, spike-like peaks or valleys caused by discontinuous movement of the sintered body during measurement are excluded. If the derivative peak of the derivative curve is 0.01 μm / sec or less, it may be said that no inflection point is substantially found in the thermal expansion curve of the sintered body of the powder of glass.

The first glass is substantially free of alkali metal oxides and BaO, and is 40 to 44% of SiO ₂ , 15 to 23% of MgO, and 28 to 36% of CaO in terms of mol% on an oxide basis. And 5 to 10% of Al ₂ O _3, and the total content of these components is 97% or more, and the molar ratio of the content of CaO to MgO represented by CaO / MgO is 1.2 to 2. It is three. The first glass is suitable when it is desired to suppress the reaction between BaO and a member group made of metal or ceramic by substantially containing no BaO.

The second glass contains substantially no alkali metal oxide and BaO, and is 34.0 to 40.0% of SiO ₂ and 14.0 to 20.0 of MgO in terms of mol% based on the oxide. %, Containing 28.0 to 36.0% of CaO and 12.0-18.0% of Al ₂ O _3, and the total content of these components is 97% or more and is represented by CaO / MgO The molar ratio of the content of CaO to MgO is 1.5 to 2.5. The second glass is substantially free of BaO, and further contains less SiO ₂ than the first glass, and is heat resistant in an environment where H ₂ O cuts the SiO ₂ network. Is a good choice if you want to keep

The third glass contains substantially no alkali metal oxide and TiO ₂ , and is 42 to 47% of SiO ₂ , 14 to 19% of MgO, and 29 to 36 of CaO in terms of mol% on an oxide basis. %, Containing ₃ to 7.5% of Al ₂ O ₃ , 0.3 to 5.5% of BaO, and 0 to 0.5% of SrO, and the total content of these components is 97% or more The molar ratio of the content of CaO to MgO represented by CaO / MgO is 2.0 to 2.3. By containing BaO, the third glass can maintain a high thermal expansion coefficient of the remaining glass without crystallization after firing. This is suitable when the thermal expansion coefficient of the metal or ceramic member group is to be matched more.

The fourth glass contains substantially no alkali metal oxide and TiO ₂ , and is 41 to 47% of SiO ₂ , 12.5 to 17.5% of MgO, CaO in terms of mol% on an oxide basis. 26 to 36%, Al ₂ O ₃ more than 7.5% and 14% or less, BaO 0.3 to 4%, the total content of these components is 97% or more, and CaO / MgO The molar ratio of the content of CaO to MgO shown is 1.75 to 2.25. Similarly to the third glass, the fourth glass can maintain the high thermal expansion coefficient of the remaining glass without being crystallized after firing by containing BaO. This is preferable in the case where it is desired to further match the thermal expansion coefficient with the metal or ceramic member group, and in the case where the flowability at high temperature is to be further enhanced than in the third glass.

  In addition, in this specification, it does not contain actively, but not containing it substantially means that the contamination by an unavoidable impurity is accept | permitted. Moreover, in this specification, an upper and lower limit is included in "-" showing a numerical range.

Next, the composition of the glass of the present invention will be described by simply displaying mol% as%.
SiO ₂ is a component that forms a network of glass, and improves the stability of the glass during glass production to prevent crystallization and is essential. Further, diopside upon glass powder sintering _{(CaO-MgO-2SiO 2)} , akermanite _{(2CaO-MgO-2SiO 2)} , CaO-MgO-SiO 2 based crystal such melilite, MgO-SiO ₂ based crystal such as forsterite When SiO ₂ -containing high expansion crystals such as Ca, SiO ₂ -based crystals, etc. are formed, they become constituents of these crystals.

When the content of SiO ₂ exceeds 44.0% in the first glass, problems such as increase in Ts and early onset of crystallization and deterioration of fluidity occur. In addition, there is a problem that it becomes difficult to melt at the time of melting. If SiO ₂ is less than 40.0% in the first glass, the stability of the glass is lowered during the production of the glass and crystals are easily precipitated in the glass, and the powder of the glass on which such crystals are precipitated is a crystal at the time of firing Because the start of the transformation is premature and lack of fluidity, the desired sealing can not be performed. In addition, problems such as devitrification occur. The preferred range of SiO ₂ in the first glass is 41.0 to 43.0%, more preferably 41.5 to 42.5%.

If SiO ₂ is more than 40.0% in the second glass, problems such as a too low coefficient of thermal expansion occur. Also, by setting SiO ₂ to 40.0% or less, heat resistance is present in the environment where H ₂ O is present at high temperature such as SOFC and H ₂ O cuts the network of SiO ₂ . You can expect the effect of maintaining the If SiO ₂ is less than 34.0% in the second glass, the stability of the glass decreases during the production of the glass and crystals are easily precipitated in the glass, and the powder of the glass on which such crystals are precipitated is a crystal at the time of firing Because the start of the transformation is premature and lack of fluidity, the desired sealing can not be performed. In addition, problems such as devitrification occur. The preferable range of SiO ₂ in the second glass is 35.0 to 40.0%, more preferably 36.0 to 39.0%, and still more preferably 37.0 to 38.0%.

In the third glass, when SiO ₂ is more than 47.0%, Ts becomes high, or the onset of crystallization becomes fast, and problems such as deterioration of fluidity occur. In addition, there is a problem that it becomes difficult to melt at the time of melting. In the third glass, if SiO ₂ is less than 42.0%, the stability of the glass is lowered during the production of the glass and crystals are easily precipitated in the glass, and the powder of the glass on which such crystals are precipitated is a crystal at the time of firing Because the start of the transformation is premature and lack of fluidity, the desired sealing can not be performed. The preferable range of SiO ₂ in the third glass is 42.0 to 46.0%, more preferably 43.0 to 45.0%.

In the fourth glass, if SiO ₂ is more than 47.0%, problems such as increase in Ts or early onset of crystallization and deterioration of fluidity occur. In addition, there is a problem that it becomes difficult to melt at the time of melting. In the fourth glass, if SiO ₂ is less than 41.0%, the stability of the glass is lowered during the production of the glass and crystals are easily precipitated in the glass, and the powder of the glass on which such crystals are precipitated is a crystal at the time of firing Because the start of the transformation is premature and lack of fluidity, the desired sealing can not be performed. The preferable range of SiO ₂ in the fourth glass is 42.0 to 46.0%, more preferably 42.0 to 45.0%.

MgO is a component of MgO-containing highly expandable crystals such as MgO-SiO ₂ -based crystals and CaO-MgO-SiO ₂ -based crystals, and is essential.

  If the content of MgO in the first glass exceeds 23.0%, the stability of the glass is likely to be reduced during glass production, or crystals are less likely to be precipitated during firing, and the crystallinity of the fired body is not increased. The residual ratio of the glass phase to the above increases and the heat resistance decreases. If the content of MgO in the first glass is less than 15.0%, devitrification occurs, or crystals are less likely to precipitate during firing, so that the degree of crystallization of the fired body does not increase, and the remaining ratio of the glass phase to the crystal phase increases. Heat resistance decreases. The preferable range of MgO in the first glass is 16.0 to 20.0%, more preferably 17.0 to 18.0%.

  If MgO is more than 20.0% in the second glass, the stability of the glass is likely to be reduced during glass production, or crystals are less likely to be precipitated during firing, and the crystallinity of the fired body is not increased. The residual ratio of the glass phase to the above increases and the heat resistance decreases. If the content of MgO in the second glass is less than 14.0%, devitrification occurs, or crystals are less likely to precipitate during firing, and the degree of crystallization of the fired body does not increase, and the remaining ratio of the glass phase to the crystal phase increases. Heat resistance decreases. The preferable range of MgO in the second glass is 14.0 to 17.0%, more preferably 15.0 to 16.5%, and still more preferably 15.5 to 16.0%.

  If MgO is more than 19.0% in the third glass, the stability of the glass tends to be lowered at the time of production of the glass, or the crystallization is rather difficult to be precipitated at the time of firing, and the crystallinity of the fired body is not increased. The residual ratio of the glass phase to the above increases and the heat resistance decreases. If the content of MgO in the third glass is less than 14.0%, devitrification occurs, or crystals are less likely to precipitate during firing, so that the degree of crystallization of the fired body does not increase, and the remaining ratio of the glass phase to the crystal phase increases. Heat resistance decreases. The preferable range of MgO in the third glass is 14.0 to 18.0%, more preferably 15.0 to 17.0%.

  In the fourth glass, if MgO is more than 17.5%, the stability of the glass tends to be lowered at the time of production of the glass, or the crystallization is rather difficult to be precipitated at the time of firing, and the crystallinity of the fired body is not increased. The residual ratio of the glass phase to the phase is increased to lower the heat resistance. If the content of MgO in the fourth glass is less than 12.5%, devitrification occurs, or crystals are less likely to precipitate during firing, so that the degree of crystallization of the fired body does not increase, and the remaining ratio of the glass phase to the crystal phase increases. Heat resistance decreases. The preferred range of MgO in the fourth glass is 14.5 to 17.5%, more preferably 15.0 to 17.0%.

CaO is a component of CaO-containing highly expandable crystals such as CaO-SiO ₂ -based crystals and CaO-MgO-SiO ₂ -based crystals, and is essential.

  If CaO is more than 36.0% in the first glass, the glass stability is likely to be reduced during glass production, or crystals are less likely to precipitate during firing, and the crystallinity of the fired body is not increased, and the crystalline phase is The residual ratio of the glass phase to the above increases and the heat resistance decreases. If CaO is less than 28.0% in the first glass, devitrification occurs, or crystals are less likely to precipitate during firing, and the degree of crystallization of the fired body does not increase, and the remaining ratio of the glass phase to the crystal phase increases Heat resistance decreases. The preferable range of CaO in the first glass is 30.0 to 35.0%, more preferably 32.0 to 34.0%.

  If CaO is more than 36.0% in the second glass, the glass stability is apt to be reduced at the time of glass production, or crystals are rather difficult to precipitate at the time of firing, and the crystallinity of the fired body is not increased. The residual ratio of the glass phase to the above increases and the heat resistance decreases. In the second glass, if CaO is less than 28.0%, devitrification occurs, or crystals are difficult to precipitate at the time of firing, and the degree of crystallization of the fired body does not increase, and the remaining ratio of the glass phase to the crystal phase increases. Heat resistance decreases. The preferable range of CaO in the second glass is 28.0 to 34.0%, more preferably 29.0 to 33.0%, and still more preferably 32.0 to 33.0%.

  If CaO is more than 36.0% in the third glass, the glass stability is apt to be reduced at the time of glass production, or crystals are rather difficult to precipitate at the time of firing, and the crystallinity of the fired body is not increased. The residual ratio of the glass phase to the above increases and the heat resistance decreases. If CaO is less than 29.0% in the third glass, devitrification occurs, or crystals are less likely to precipitate during firing, and the degree of crystallization of the fired body does not increase, and the remaining ratio of the glass phase to the crystal phase increases. Heat resistance decreases. The preferable range of CaO in the third glass is 32.0 to 35.0%, more preferably 33.0 to 35.0%.

  If CaO is more than 36.0% in the fourth glass, the glass stability is apt to be reduced at the time of glass production, or crystals are rather difficult to precipitate at the time of firing, and the crystallinity of the fired body is not increased. The residual ratio of the glass phase to the above increases and the heat resistance decreases. In the fourth glass, if CaO is less than 26.0%, devitrification occurs, or crystals are less likely to precipitate during firing, and the crystallinity of the fired body does not increase, and the remaining ratio of the glass phase to the crystal phase increases. Heat resistance decreases. The preferable range of CaO in the fourth glass is 28.0 to 32.0%, more preferably 29.0 to 31.0%.

Al ₂ O ₃ is an essential component for improving the stability in glass production and serving to adjust Tc or maintain the adhesion with metals, and is essential.

When the content of Al ₂ O ₃ exceeds 10% in the first glass, problems such as high Ts and low thermal expansion coefficient occur. If the content of Al ₂ O ₃ in the first glass is less than 5%, the glass becomes unstable, causing problems such as devitrification. The preferred range of Al ₂ O ₃ in the first glass is 6.0 to 9.0%, more preferably 7.0 to 8.0%.

In the second glass, when the content of Al ₂ O ₃ exceeds 18.0%, problems such as Ts becoming too high, crystallization temperature becoming too high, and a thermal expansion coefficient becoming low occur. If the content of Al ₂ O ₃ in the second glass is less than 12.0%, the crystallization temperature is too low, which causes problems such as deterioration of fluidity and too high thermal expansion coefficient. The preferable range of Al ₂ O ₃ in the second glass is 13.0 to 17.0%, more preferably 14.0 to 16.0%.

In the third glass, when the content of Al ₂ O ₃ exceeds 7.5%, problems such as Ts becoming too high, crystallization temperature becoming too high, and a thermal expansion coefficient becoming low occur. If the content of Al ₂ O ₃ in the third glass is less than 3.0%, the crystallization temperature is too low, which causes problems such as deterioration of fluidity and an increase in thermal expansion coefficient. The content of Al ₂ O ₃ in the third glass is preferably 4.5 to 5.5%.

In the fourth glass, when the content of Al ₂ O ₃ exceeds 14.0%, problems such as Ts becoming too high, crystallization temperature becoming too high, and a thermal expansion coefficient becoming low occur. If the content of Al ₂ O ₃ in the fourth glass is 7.5% or less, the crystallization temperature becomes too low, which causes problems such as deterioration of fluidity and too high thermal expansion coefficient. The content of Al ₂ O _{3 in} the fourth glass is preferably 8.0 to 9.0%.

  BaO is a component for adjusting the degree of crystallinity or fluidity, improving the adhesion with a metal member, and the like. BaO is present in the remaining glass phase without crystallization after firing, and the thermal expansion coefficient of the remaining glass phase is maintained high to further match the thermal expansion coefficient with the metal or ceramic member group. . On the other hand, BaO may react with a member group made of metal or ceramic, so it is preferable not to contain BaO in the case where it is desired to suppress these.

  The first glass and the second glass, which are most suitable for suppressing the reaction between BaO and a member group made of metal or ceramic, do not substantially contain BaO.

On the other hand, in the third glass and the fourth glass, for which the thermal expansion coefficient of the metal or ceramic member group is to be matched more by maintaining the thermal expansion coefficient of the remaining glass without crystallization after firing high. Contains BaO. In the third glass and the fourth glass, the range of the content of Al ₂ O ₃ is different, so the range of the content of BaO is different.

In the case of the third glass, the content of Al ₂ O ₃ is ₃ to 7.5%, and the content of BaO is 0.3 to 5.5%. If the content of BaO exceeds 5.5%, the thermal expansion coefficient becomes too high, or the crystallization temperature becomes too high. If BaO is less than 0.3%, the effect of maintaining the thermal expansion coefficient of the remaining glass without crystallization is likely to be insufficient. The preferred range of BaO is 0.5 to 2%, more preferably 0.5 to 1.0%.

In the case of the fourth glass, the content of Al ₂ O ₃ is more than 7.5% and 14.0% or less, and the content of BaO is 0.3 to 4.0%. If the content of BaO exceeds 4.0%, the thermal expansion coefficient becomes too high, or the crystallization temperature becomes too high. If BaO is less than 0.3%, the effect of maintaining the thermal expansion coefficient of the remaining glass without crystallization is likely to be insufficient. The preferred range of BaO is 0.5 to 2%, more preferably 0.5 to 1.0%.

  In the first glass, the molar ratio CaO / MgO of CaO to MgO is 1.2 to 2.3. When CaO / MgO is less than 1.2 or more than 2.3, the crystallization starts too fast at the time of firing, and the fluidity is lowered, and desired sealing can not be performed. CaO / MgO is preferably 1.5 to 2.2, more preferably 1.7 to 2.1.

  In the second glass, the molar ratio CaO / MgO of CaO to MgO is 1.5 to 2.5. When CaO / MgO is less than 1.5 or more than 2.5, crystallization starts too quickly at the time of firing, and the flowability is reduced, and desired sealing can not be performed. CaO / MgO is preferably 1.5 to 2.0.

  In the third glass, the molar ratio CaO / MgO of CaO to MgO is 2.0 to 2.3. When CaO / MgO is less than 2.0 or more than 2.3, the onset of crystallization at the time of firing becomes too fast, and the flowability decreases to make it impossible to perform desired sealing and the like. CaO / MgO is preferably 2.0 to 2.1.

  In the case of the fourth glass, the molar ratio CaO / MgO of CaO to MgO is 1.75 to 2.25. If the CaO / MgO content is less than 1.75 or more than 2.25, the onset of crystallization at the time of firing becomes too fast, and the flowability decreases to make it impossible to perform desired sealing and the like. CaO / MgO is preferably 1.75 to 2.1, more preferably 1.75 to 2.0.

  In the third glass, SrO may be contained in a range of 0.5% or less for the purpose of adjusting thermal expansion or flowability. In the third glass, when the content of SrO exceeds 0.5%, the onset of crystallization becomes too fast, and the fluidity decreases. In the third glass, it is desirable not to substantially contain SrO.

  The glass of the present invention is typically composed of the above components, and the total amount of the above components is 97% or more in each of the first glass, the second glass, the third glass, and the fourth glass. The total amount is preferably 98% or more, more preferably 99% or more. In other words, the glass of the present invention may contain other components without impairing the object of the present invention, in which case the total content of such components is 3% or less, 2% The following is preferable, and typically it is 1.0% or less.

Typically, B ₂ O ₃ is not contained in the glass of the present invention, and even if it is contained, its content is preferably 1% or less. If B ₂ O ₃ is more than 1%, the proportion of the glass phase remaining in the crystallized glass becomes high, causing an inflection point in the thermal expansion curve, and in the temperature range corresponding to the inflection point There is a possibility that a strong shear stress and strain may be generated at the interface between the object and the crystallized glass to cause cracks and peeling. In addition, B ₂ O ₃ may be volatilized during high temperature operation of the SOFC to contaminate the surroundings. The content of B ₂ O ₃ is more preferably 0.5% or less, and typically 0.2% or less. B ₂ O ₃ is a component that may be contained when it is desired to improve the flowability at the time of firing.

  In the glass of the present invention, ZnO is not contained or not contained for the following reasons. In the glass of the present invention, the content of ZnO is preferably 2.0% or less, more preferably 1.0% or less, and further preferably substantially free.

  ZnO is a component for lowering Ts, adjusting the degree of crystallinity, improving adhesion with a metal member, and the like, but it is known that oxygen defects occur at high temperatures of 400 ° C. or higher. If the content of ZnO is more than 2.0%, crystal defects such as intercrystalline zinc and oxygen vacancies may occur due to oxygen defects, and a highly reliable seal may not be obtained. If crystal defects occur, the characteristics of the crystals and residual glass in the crystallized glass may be changed by being exposed to high temperatures for a long time, resulting in a decrease in sealing strength and a change in expansion coefficient. As a result, strong shear stress and distortion may occur at the interface between the object to be sealed and the crystallized glass at the seal portion, which may cause cracks and peeling. A component such as ZnO is not preferable for SOFC members that are intended to be used for a long time at high temperatures exceeding 700 ° C.

The glass of the present invention is substantially free of alkali metal oxides, ie, Li ₂ O, Na ₂ O and K ₂ O. When the glass of the present invention is used to seal the constituent members of SOFC, the alkali metal ions that are easily thermally diffused may diffuse into the ceramic member or the metal member, and the characteristics of the SOFC may be significantly degraded.

The third and fourth glasses contain substantially no TiO ₂ . In the third glass and the fourth glass, when TiO ₂ is contained, the crystallization temperature and the thermal expansion coefficient become too low.

In the first glass and the second glass, TiO ₂ is a component that may be contained as a control component of the crystallinity degree and the thermal expansion coefficient. However, also in the first glass and the second glass, if the content of TiO ₂ exceeds 0.5%, the crystallization temperature and the thermal expansion coefficient become too low. Therefore, when TiO ₂ is contained in the first glass and the second glass, the content is preferably 0.5% or less, more preferably 0.1% or less.

  In the first glass, the second glass, and the fourth glass, SrO may be contained to adjust thermal expansion or flowability, etc., but if it exceeds 1.0%, the onset of crystallization becomes faster Too much, the liquidity decreases. Therefore, in the first glass, the second glass and the fourth glass, the content of SrO is preferably 1.0% or less, more preferably 0.5% or less, and substantially not containing desirable.

In the glass of the present invention, when the content of ZrO ₂ is adjusted to 0.2 to 2.0% as a component adjusting the crystallinity and the thermal expansion coefficient, the flowability at the time of firing is preferably improved and the thermal expansion coefficient is preferably increased. There is. If the content of ZrO ₂ is more than 2.0%, the crystallization temperature becomes too high, or the thermal expansion coefficient becomes too high. Therefore, when the glass of the present invention contains ZrO ₂ , its content is preferably 2.0% or less, more preferably 1.0 or less, and still more preferably 0.5% or less.

  In the glass of the present invention, in general, oxides such as rare earths such as La, Y, Sc, Ge, Gd, Fe, Cu, V, Cr, Mn, Co, Ni, Mo, transition metals, etc. change in valence. It is desirable not to contain easily because there is a possibility that a stable seal can not be obtained, for example, the crystal structure etc. is changed and crystals different from the desired crystal are precipitated.

However, for the purpose of improving the fluidity, 0.1 to 3% of a rare earth or transition metal oxide may be contained in a range in which a stable seal can be obtained. In particular, the addition of La ₂ O ₃ can greatly improve the flowability of the glass. In the glass of the present invention, the content of La ₂ O ₃ is preferably 0.1 to 3%, more preferably 0.3 to 2%, more preferably 0.5 to 1.5%.

In the glass of the present invention, low melting point components such as Bi ₂ O ₃ , Sb ₂ O ₃ , TeO ₂ , AgO, P ₂ O ₅ , WO, etc. diffuse into the ceramic member or metal member and the characteristics of SOFC are significantly deteriorated. It is desirable not to contain because there is a risk.

However, Bi ₂ O ₃ may be contained in the glass of the present invention in the range of 0.1 to 3.0% for the purpose of improving the fluidity of the glass, and the content thereof is 0.3 to 1. 5% is more preferable.

The glass of the present invention may contain SnO ₂ in a proportion of 0.1 to 3.0% for the purpose of improving the fluidity of the glass, and its content is more preferably 0.5 to 2.0%. .

  Also, the glass of the present invention preferably contains substantially no lead, that is, PbO, in order to reduce the load on the environment.

The glass of the present invention is a SiO ₂ -MgO-CaO-Al ₂ O ₃ based glass having the above composition, and contains no or a large amount of ZnO and B ₂ O ₃ in the fired body of the powder. It has a characteristic that it does not have an inflection point in the thermal expansion curve and can suppress the occurrence of crystal defects. Due to such characteristics, the glass of the present invention is suitably used for sealing, bonding, etc. of members selected from a group of members particularly made of metal or ceramic.

  The glass of the present invention may be in any form but is usually in the form of powder. The method for producing the glass of the present invention in powder form is not particularly limited. For example, in the obtained glass, the raw material mixture in which the type and ratio of the raw materials are appropriately adjusted so as to be in the above composition range can be manufactured by heating and melting and cooling, and then powdered.

  The glass paste of the present invention is produced by mixing the powder of the glass of the present invention with an organic vehicle or the like for imparting printability and the like. The organic vehicle is obtained by dissolving a binder such as ethyl cellulose in an organic solvent such as α-terpineol. The green sheet of the present invention is obtained by forming the powder of the glass of the present invention into, for example, a glass paste and forming it into a sheet.

  In the glass paste of the present invention, a ceramic filler may be mixed with the powder of the glass of the present invention in order to adjust the fluidity, the thermal expansion coefficient, and the reactivity with a member made of metal or ceramic. Examples of the ceramic filler include zirconium oxide, stabilized zirconium oxide containing Y, stabilized zirconium containing Ca, and the like.

  The mixing ratio of the ceramic filler is preferably 0.1 to 30% by volume, more preferably 0.3 to 20% by volume, still more preferably 0.5 to 10% by volume, based on the total volume of the glass powder and the ceramic filler It is. When the mixing ratio of the ceramic filler is too large, the flowability is deteriorated. If the mixing ratio of the ceramic filler is too small, the effect of adjusting the fluidity, the thermal expansion coefficient, and the reactivity with the member made of metal or ceramic can not be obtained.

  The particle size of the glass powder and the ceramic filler is preferably about 0.5 to 45 μm. If the particle size is fine, crystallization can be accelerated, but it may become too early to deteriorate the fluidity. Coarse particles can maintain flowability relatively, but may not be usable when the seal thickness is low due to the structure such as SOFC.

  In the present specification, the particle size indicates the volume-based 50% particle size in the cumulative particle size distribution, specifically, the cumulative particle size of the particle size distribution measured using a laser diffraction / scattering type particle size distribution measuring apparatus In the curve, the particle size is shown when the integrated amount occupies 50% by volume.

  The glass paste of the present invention is applied and fired on a portion to be sealed, such as the surface of a ceramic member and a metal member constituting a fuel manifold and cell of SOFC, for example, to form crystallized glass (sintered body). Do. Moreover, such a component may be sealed using the green sheet of the present invention.

  In addition, the method of manufacturing SOFC by sealing the ceramic member or metal member of SOFC with the glass paste of the present invention or the green sheet of the present invention in this way is a method of manufacturing the SOFC of the present invention. The produced SOFC is the SOFC of the present invention.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples.

[Manufacture of glass powder]
The raw materials are prepared and mixed so that the composition shown in the column of composition in Tables 1 to 7 is expressed by mol%, and they are melted for 1 hour using a platinum crucible in an electric furnace at 1450-1550 ° C. After molding, it was crushed by a ball mill and then coarse particles were removed by a sieve of 150 mesh to obtain a glass powder.

  Examples 1-1 to 1-12 and Examples 1-17 to 1-31 are examples of the first glass, and Examples 1-13 to 1-16 are comparative examples of the first glass. Examples 2-1 to 2-10 are examples of the second glass, and examples 2-11 to 2-18 are comparative examples of the second glass. Examples 3-1 to 3-8 are examples of the third glass, and examples 3-9 to 3-13 are comparative examples of the third glass. Examples 4-1 to 4-8 are examples of the fourth glass, and examples 4-9 to 4-10 are comparative examples of the fourth glass.

[Evaluation]
(Differential thermal analysis)
The Tg (unit: ° C), Ts (unit: ° C), and Tc (unit: ° C) of each glass powder were measured using a differential thermal analyzer. The obtained results are shown in the table. In addition, in addition, Tc-Ts is shown in the table.

(Measurement of thermal expansion curve)
After firing, each glass powder is sintered at 950 ° C. for 1 hour to obtain a sintered body, which is processed into a cylindrical shape with a diameter of 5 ± 0.5 mm and a length of 2 ± 0.05 cm. Thermal expansion curve at 50 to 950 ° C (horizontal axis: temperature, vertical axis: length of sintered body) is measured at a temperature rising rate of 10 ° C / min with a dilatometer Thermoplus 2 system TMA 8310, and the average linear thermal expansion coefficient α (unit: 10) ^-7 / ° C) was calculated. The obtained results are shown in the table.

Moreover, the derivative curve was created about the thermal expansion curve obtained above, and the derivative peak was calculated | required by said method. The glass obtained in each of the above examples has a differential peak of 0.01 μm / sec or less in each of the glass of the example and the glass of the comparative example, and the inflection point (bending) is a glance at the thermal expansion curve of the sintered body It was not done. As described in the comparative example of Japanese Patent No. 5365517, an inflection point is confirmed in any of the glasses containing B ₂ O ₃ .

(Liquidity)
The flowability of each glass powder was evaluated as follows. That is, 3 g of glass powder was press-formed to prepare a sample (flow button) having a diameter of 1/2 inch (= 12.7 mm), which was heated up to 950 ° C. to flow to evaluate fluidity . The diameter (unit; mm) of the sample after temperature rising was measured, and it showed as "FB diameter" in the table | surface.

From the obtained "FB diameter", the flowability was evaluated according to the following criteria. The results are shown in the table.
<Evaluation criteria for liquidity>
Less than 11.5 mm: x (A stable seal can not be made even under load.)
11.5 mm or more and less than 12 mm: Δ (A stable seal can be made when the load is sufficient.)
12 mm or more and less than 13 mm: ((A stable seal can be obtained without load.)
13 mm or more: ◎ (Can seal more stably.)

Further, Example 1-2, Example 3-1, the glass powder by calcining the obtained the sintered body diopside example _{4-1 (CaO-MgO-2SiO 2} ), akermanite (2CaO-MgO-2SiO ₂ ) Was precipitated. In Examples 1-16, 2-17, and 2-18, devitrification was confirmed. "-" In the table indicates that the data was not measured. In Example 2-15, since Tc was over 1050 ° C. and was over the measurement range, it could not be measured.

  The glass of the present invention can be used for the production of SOFC and the production of an oxygen generator.

Claims (16)

Substantially alkali metal oxide and BaO are not included, and 40 to 44% of SiO ₂ , 15 to 23% of MgO, 28 to 36% of CaO, Al ₂ O ₃ in terms of mol% on the basis of oxide 5 to 10%, the total content of these components is 97% or more, and the molar ratio of the content of CaO to MgO represented by CaO / MgO is 1.2 to 2.3. Glass to be. Substantially alkali metal oxide and BaO free, 34 to 40% of SiO ₂ , 14 to 20% of MgO, 28 to 36% of CaO, Al ₂ O ₃ in terms of mol% on an oxide basis 12 to 18% contained, the total content of these components is 97% or more, and the molar ratio of the content of CaO to MgO represented by CaO / MgO is 1.5 to 2.5. Glass to be. Substantially alkali metal oxide and TiO ₂ free, 42 to 47% of SiO ₂ , 14 to 19% of MgO, 29 to 36% of CaO, Al ₂ O _{3 in} terms of mol% on an oxide basis Containing 3 to 7.5% of BaO, 0.3 to 5.5% of BaO, and 0 to 0.5% of SrO, and the total content of these components is 97% or more, as indicated by CaO / MgO Glass characterized in that the molar ratio of the content of CaO and MgO is 2.0 to 2.3. Substantially alkali metal oxide and TiO ₂ free, 41 to 47% of SiO ₂ , 12.5 to 17.5% of MgO, 26 to 36% of CaO, in terms of mol% on an oxide basis More than 7.5% and 14% or less of Al ₂ O ₃ and 0.3 to 4% of BaO, the total content of these components is 97% or more, and CaO / MgO represented by CaO / MgO Glass characterized in that the molar ratio of the content is from 1.75 to 2.25.   The glass according to any one of claims 1 to 4, which contains substantially no oxide of La, Y, Sc, Ge, Gd, Fe, Cu, V, Cr, Mn, Co, Ni or Mo. Further, the glass according to any one of claims 1 to 4 containing _La 2 _{O 3} 0.1 to 3 mol%.   The glass according to any one of claims 1 to 6, wherein the softening point is above 820 ° C. The glass according to any one of claims 1 to 7, wherein the average linear expansion coefficient at 50 to 950 ° C of the fired body obtained by firing the powder at 950 ° C is 84 × 10 ^{-7 to} 105 × 10 ^-7. / ° C glass.   The glass according to any one of claims 1 to 8, which contains ZnO in a range of 2 mol% or less. The glass according to any one of claims 1 to 9, which contains B ₂ O ₃ in a range of 1 mol% or less.   The glass according to any one of claims 1 to 10 substantially free of lead. A glass according to any one of claims 1 to 11, and characterized in that CaO-MgO-SiO ₂ based crystal is deposited on the fired body obtained by firing the powder at 900 to 1100 ° C. Glass to be   The glass paste containing the powder of the glass in any one of Claims 1-12.   The green sheet containing the powder of the glass in any one of Claims 1-12.   It is a manufacturing method of a solid oxide fuel cell which has a process of sealing members which consist of ceramics or a metal mutually, and seals the above-mentioned members together using powder of the glass in any one of Claims 1-12. Of producing a solid oxide fuel cell.   It is a solid oxide fuel cell which has one or more sealing parts in which members which consist of ceramics or a metal are sealed mutually, and at least one of the sealing parts in any one of claims 1 to 12 A solid oxide fuel cell sealed with a fired body obtained by firing a glass powder of