JP2007161569A - Glass composition for sealing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a powdery composition which is substantially free of alkali metals and useful for forming highly thermally expansible crystallized glass, and can join a metal and a ceramic by firing at a temperature of ≤900°C. <P>SOLUTION: The powdery composition useful for forming the crystallized glass for sealing comprises a glass powder substantially free of alkali metals and containing, by mass in terms of oxide, 10-30% SiO<SB>2</SB>, 20-30% B<SB>2</SB>O<SB>3</SB>, 10-40% CaO, 15-40% MgO, 0-10% of BaO+SrO+ZnO, 0-5% La<SB>2</SB>O<SB>3</SB>, 0-5% Al<SB>2</SB>O<SB>3</SB>, and 0-3% RO<SB>2</SB>(wherein, R represents Zr, Ti or Sn). The crystallized glass, formed by firing the powdery composition at 900±50°C, has a coefficient of thermal expansion at 50-550°C of 90-120×10<SP>-7</SP>/°C. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a glass composition used for sealing metal and ceramic, metal and metal, ceramic and ceramic, and more specifically, a seal portion of a solid oxide fuel cell (SOFC), for example, a SOFC cell. It is related with the glass composition for sealing used as a sealing material in the seal part between this and the fuel manifold which attaches this.

  As a sealing material for a solid oxide fuel cell (SOFC), a mixed powder of amorphous glass powder and high expansion ceramic powder has been used (see Patent Document 1). However, SOFC has a very high operating temperature of 700 to 1000 ° C., and the high temperature viscosity of amorphous glass is lowered, so that the sealing material is easily deformed and difficult to support itself. There is a problem that application is limited only to a structural portion that is stably supported in advance so that the sealing material itself does not need to support (including its own weight).

Further, crystallized glass mainly depositing lithium disilicate or SiO ₂ —Al ₂ O ₃ —ZnO—K ₂ O—Na ₂ O-based amorphous glass has been proposed (respectively, Patent Document 2 and 3). However, since these sealing materials contain a large amount of alkali metal in the crystal phase precipitated from the original glass or the remaining glass phase, there is a problem in durability of insulation and sealing properties, and SOFC has been used for a long time. If used, the insulation and seal are expected to break easily under the influence of hot and humid conditions in which it operates.

JP-A-8-134434 JP 2003-238201 A Japanese Patent Application Laid-Open No. 2004-123496

  In the above background, the present invention provides a glass composition capable of sealing a metal and a ceramic by firing at 900 ° C. or less for forming a highly expandable crystallized glass substantially free of alkali metal. The purpose is to provide.

As a result of repeated studies to solve the above problems, the present inventors have found that when the SiO ₂ —B ₂ O ₃ —CaO—MgO-based glass composition is in a specific component range, this glass composition It is found that a crystallized glass having a thermal expansion coefficient of 90 to 120 × 10 ⁻⁷ / ° C. (50 to 550 ° C.) that is compatible with metals and ceramics can be formed by firing a glass powder made of Based on this knowledge, further studies have been made and the present invention has been completed.

That is, the present invention provides the following.
(1) Substantially free of alkali metals, in terms of oxides,
SiO ₂ ... 10 to 30% by mass,
B ₂ O ₃ 20-30% by mass,
CaO ... 10 to 40% by mass,
MgO 15 to 40% by mass,
BaO + SrO + ZnO ... 0-10 mass%,
La ₂ O ₃ ... 0 to 5% by mass,
Al ₂ O ₃ ... 0 to 5 mass%, and RO ₂ ... 0 to 3 mass% (here, R represents Zr, Ti, or Sn).
A crystallized glass formed by firing glass powder made of this glass composition at a temperature of 900 ± 50 ° C. has a thermal expansion coefficient at 50 to 550 ° C. of 90 to 120 ×. A glass composition for sealing, which is 10 ⁻⁷ / ° C.
(2) The glass composition according to 1 above, wherein the CaO content / MgO content is 0.4 to 2.0 in terms of mass ratio.
(3) The glass composition according to the above 1 or 2, wherein the SiO ₂ content / B ₂ O ₃ content is 0.33 to 1.33 by mass ratio.
(4) Any of 1 to 3 above, wherein the total content of SiO ₂ and B ₂ O ₃ is 30 to 50% by mass, and the total content of CaO and MgO is 44 to 65% by mass. Glass composition.
(5) A glass powder comprising the glass composition according to any one of 1 to 4 above, having an average particle diameter of 5 to 250 μm.
(6) A glass / ceramic powder comprising 100 parts by mass of the glass powder comprising the glass composition of any one of 1 to 4 and 0.01 to 20 parts by mass of zirconia powder.
(7) One or more ceramic powders selected from the group consisting of the glass powder of any one of 1 to 4 above and magnesia, forsterite, steatite, wollastonite, and precursors thereof; One or more ceramic powders selected from the group consisting of magnesia, forsterite, steatite, wollastonite and precursors thereof with respect to 100 parts by mass of the glass powder Glass / ceramic powder containing 0.01 to 5 parts by mass.
(8) The glass / ceramic powder according to the above 6 or 7, wherein the glass powder has an average particle size of 5 to 250 μm.

  According to the present invention having the above-described configurations, it is possible to provide a powder of a glass composition that crystallizes when fired to give a crystallized glass having a high thermal expansion coefficient in a form that is substantially free of alkali metals. Therefore, as a sealing material for parts that need to seal metal and ceramics, metal and metal, ceramics and ceramics used at high temperatures (for example, solid oxide fuel cells and exhaust gas sensor seals) Can be used. Even if it is exposed to a high temperature and high humidity of 700 to 1000 ° C. for a long period of time in a solid oxide fuel cell or the like, there is no risk of the insulation being impaired, and there is no risk of a decrease in viscosity at such a high temperature. If it is used as a sealing material for a sealing portion of a solid oxide fuel cell or the like, the insulation of the sealing portion and the durability of the sealing performance can be enhanced.

  In the sealing glass composition of the present invention, for example, the glass powder is formed into a paste form, filled into a portion to be sealed of the SOFC composed of the fuel manifold and the cell, and fired, whereby the fuel manifold and the cell are formed. Bonded with the surface of the ceramics and metals constituting it, it becomes crystallized glass and seals them. Firing may be performed at 900 ° C. or lower (eg, 900 ° C.).

  The glass powder comprising the glass composition for sealing of the present invention is a glass raw material (not crystallized) obtained by preparing a metal oxide as a raw material, mixing and melting (for example, at 1400 to 1500 ° C.) and then cooling. ) May be pulverized.

  In the present invention, “substantially does not contain an alkali metal” means that a raw material containing an alkali metal as a main component is not used at all, and is derived from the raw material of each component constituting the glass and impurities of the inorganic filler. The use of a mixture of a trace amount of alkali metal is not excluded. The alkali metal content of the glass composition for sealing of the present invention is preferably 100 ppm or less, more preferably 30 ppm or less, and particularly preferably 10 ppm or less.

  Moreover, since it is preferable that the glass composition for sealing of this invention is lead-free (lead is less than 1000 ppm) from a viewpoint on environmental protection, you should avoid adding the material containing lead.

In the glass composition for sealing of the present invention, SiO ₂ is a component that forms a glass network, in order to improve the stability of the glass and prevent crystallization during the production of the glass base for the production of glass powder. In addition, it is an essential component for generating CaO—MgO—SiO ₂ (diopside, etc.) and MgO—SiO ₂ (fortelite, etc.) high-expansion crystals in the calcination after pulverization. A glass composition that mainly precipitates CaO—MgO—SiO ₂ (diopside, etc.) crystals has little transformation of the crystal phase due to the firing temperature, and tends to stabilize the strength of the bulk body after crystallization.
On the other hand, if crystals are precipitated in the glass raw material, the glass powder obtained by crushing the glass will start crystallization earlier at the time of sealing firing, and therefore the flowability of the composition will be reduced early from the beginning of firing. Thus, the flow is hindered, and a problem that a gap is formed between the object to be sealed after firing is likely to occur, which is not preferable. If the content of SiO ₂ is less than 10% by mass, stability during production of the glass raw material is lowered, which is not preferable. Moreover, it is not preferable that the content of SiO ₂ exceeds 30% by mass. If it exceeds 30% by mass, the linearity of the thermal expansion curve of the crystallized glass obtained by firing decreases and an inflection point appears, but in the temperature region corresponding to the inflection point, the sealing portion is sealed. This is because a strong shear stress and strain are generated at the interface between the object to be deposited and the crystallized glass, causing cracks and peeling. Accordingly, the content of SiO ₂ is preferably 10% by mass or more, more preferably 12% by mass or more, still more preferably 14% by mass or more, and preferably 30% by mass or less, more preferably 25% by mass or less, More preferably, it is 20 mass% or less, Most preferably, it is 18 mass% or less. Therefore, the content of SiO ₂ can be, for example, 10 to 30% by mass, 12 to 25% by mass, or 14 to 20% by mass.

B ₂ O ₃ is a component that forms a network of glass. In order to prevent crystallization by improving the stability of the glass at the time of producing the glass raw material, and in firing after powdering, MgO · B ₂ O ₃ is an essential component for producing CaO · B ₂ O ₃ -based high expansion crystals. If the content of B ₂ O ₃ is less than 20% by mass, the stability during production of the glass raw material is lowered, and crystals are liable to precipitate, which is not preferable. As described above in relation to the SiO ₂ content, it is not preferable that crystals are precipitated during the production of the glass raw material. On the other hand, if the content of B ₂ O ₃ exceeds 30% by mass, the linearity of the thermal expansion curve decreases (an inflection point appears), which is not preferable. Therefore, the content of B ₂ O ₃ is preferably 20% by mass or more, more preferably 22% by mass or more, still more preferably 24% by mass or more, and preferably 30% by mass or less, more preferably 28% by mass. Hereinafter, it is more preferably 26% by mass or less. The content of B ₂ O ₃ is, for example, can be 20 to 30 wt%, 22 to 30 wt%, or 24 to 28 wt%, etc. to.

A mass ratio of SiO ₂ content / B ₂ O ₃ content of less than 0.33 is not preferable because stability during production of the glass raw material is lowered. Further, when the mass ratio of SiO ₂ content / B ₂ O ₃ content is 1.33 or more, the degree of crystallinity after sealing firing does not increase, and the residual ratio of the glass phase to the crystal phase increases. Since an inflection point (glass transition point) appears in the expansion curve and distortion occurs in the seal part, it is not preferable. Accordingly, the mass ratio of SiO ₂ content / B ₂ O ₃ content is preferably 0.33 or more, more preferably 0.45 or more, still more preferably 0.5 or more, and preferably 1.33 or less. More preferably, it is 1.3 or less, More preferably, it is 1.25 or less. By changing this ratio, the coefficient of thermal expansion can be finely adjusted (that is, increasing this ratio decreases the coefficient of thermal expansion), so the heat of ceramics and metal used in the SOFC cell can be reduced. When the expansion coefficients are different, matching can be achieved by laminating several types of materials with different ratios.

CaO is an essential component for the formation of CaO—B ₂ O ₃ , CaO—MgO—B ₂ O ₃ , and CaO—MgO—SiO ₂ high expansion crystals. If the content of CaO is less than 10% by mass or exceeds 40% by mass, the stability during production of the glass raw material is lowered, the flowability of the composition during powder firing is lowered, and the flow is inhibited. Therefore, it is not preferable. Therefore, the content of CaO is preferably 10% by mass or more, more preferably 15% by mass or more, further preferably 20% by mass or more, and preferably 40% by mass or less, more preferably 36% by mass or less, Preferably it is 31 mass% or less.

MgO is an essential component for the production of highly expandable crystals of MgO—SiO ₂ , MgO—B ₂ O ₃ , CaO—MgO—B ₂ O ₃ , and CaO—MgO—SiO ₂ . If the content of MgO is less than 15% by mass, the degree of crystallinity after sealing firing does not increase, and the residual ratio of the glass phase to the crystal phase increases. On the other hand, if the content of MgO exceeds 40% by mass, the stability during production of the glass raw material is lowered, the flowability of the composition during powder firing is lowered, and the flow is hindered. Therefore, the content of MgO is preferably 15% by mass or more, more preferably 20% by mass or more, further preferably 22% by mass or more, and preferably 40% by mass or less, more preferably 35% by mass or less, Preferably it is 30 mass% or less.

  When the mass ratio of CaO content / MgO content is less than 0.4 or more than 2.0, the stability during the production of the glass raw material decreases, the flowability of the composition during powder firing decreases, and the flow Is not preferred because it is inhibited. Further, a glass composition having a smaller mass ratio of CaO content / MgO content has less transformation of the crystal layer due to the firing temperature, and tends to stabilize the strength of the bulk body after crystallization. Accordingly, the mass ratio of CaO content / MgO content is preferably 0.4 or more, more preferably 0.45 or more, still more preferably 0.66 or more, and particularly preferably 1.1 or more. And, Preferably it is 2 or less, More preferably, it is 1.6 or less, More preferably, it is 1.4 or less. Therefore, the mass ratio of CaO content / MgO content can be, for example, 0.45 to 1.4, 0.66 to 1.25, 1.1 to 1.25, and the like. By changing this ratio, it becomes possible to finely adjust the flowability and crystallinity of the composition during sealing firing (that is, increasing this ratio decreases the thermal expansion coefficient).

If the total content of SiO ₂ and B ₂ O ₃ is less than 30% by mass, the stability during the production of the glass raw material is unfavorable, and if it exceeds 50% by mass, the thermal expansion coefficient decreases. Therefore, it is not preferable. Therefore, the total of the SiO ₂ content and the B ₂ O ₃ content is preferably 30% by mass or more, more preferably 33% by mass or more, still more preferably 35% by mass or more, particularly preferably 40% by mass or more, and The content is preferably 50% by mass or less, more preferably 48% by mass or less, still more preferably 45% by mass or less, and particularly preferably 43% by mass or less. Therefore, the total content of SiO ₂ and B ₂ O ₃ content, for example, 35 to 50 wt%, may be 40 to 48 mass%, and the like.

  If the total of the CaO content and the MgO content is less than 44% by mass, the degree of crystallization after sealing firing does not increase, and the residual ratio of the glass phase to the crystal phase increases, which is not preferable. If the total of the CaO content and the MgO content exceeds 65% by mass, the stability during the production of the glass raw material is lowered, which is not preferable. Therefore, the total of the CaO content and the MgO content is preferably 44% by mass, more preferably 48% by mass, still more preferably 50% by mass, and preferably 65% by mass or less, more preferably 63% by mass or less. More preferably, it is 61% by mass or less.

  BaO, SrO, and ZnO are components that are useful for adjusting the crystallinity and maintaining the adhesion to the metal. If the total content of BaO, SrO and ZnO exceeds 10% by mass, the degree of crystallinity after sealing firing will not increase, the residual ratio of the glass phase to the crystal phase will increase, and the heat resistance will decrease. Since corrosion due to the reaction proceeds, it is not preferable. Therefore, the total content of BaO, SrO, and ZnO is preferably 10% by mass or less, more preferably 5% by mass or less, and still more preferably 1% by mass or less.

La ₂ O ₃ is a component useful for adjusting the degree of crystallinity and maintaining adhesion to metal. If the content of La ₂ O ₃ exceeds 5% by mass, the glass becomes unstable during the production of the glass raw material, which is not preferable. Therefore, the content of La ₂ O ₃ is preferably 5% by mass or less, more preferably 0.1 to 3% by mass.

Al ₂ O ₃ is a component useful for improving the stability during the production of the glass raw material, adjusting the crystallization start temperature, and maintaining the adhesive force with the metal. When the content of Al ₂ O ₃ exceeds 5% by mass, the thermal expansion coefficient decreases, which is not preferable. Therefore, the content of Al ₂ O ₃ is preferably 5% by mass or less, more preferably 0.5 to 3% by mass.

RO ₂ (wherein R represents Zr, Ti, or Sn) is a component useful for improving crystallinity. If the content of RO ₂ exceeds 3% by mass, the glass becomes unstable during the production of the glass raw material, which is not preferable. Therefore, the content of RO ₂ is preferably 3% by mass or less, more preferably 0.1 to 1% by mass.

In addition to the above components, CaO, MgO, BaO are used for the purpose of improving stability during glass production, suppressing reaction with metals, improving adhesion between metals and glass sealing materials, and adjusting the types and ratios of precipitated crystals. A part of SrO and ZnO can be added in Fe ₂ O ₃ , CuO, CoO, NiO, Ln ₂ O ₃ (lanthanoid), Bi ₂ O ₃ in a total amount of 3% by mass or less.

  The glass powder made of the glass composition of the present invention is required to have high fluidity during firing because it needs to shrink once during firing and wet the surface of the metal or ceramic while softening and flowing. For this purpose, it is preferable to adjust the particle size according to dry pulverization conditions so that the average particle size is 5 to 250 μm and the maximum particle size is 500 μm or less.

  Here, if the particle size is too small, crystallization starts earlier, the flowability of the composition at the time of sealing firing is reduced and the flow is hindered, so it is necessary to increase the number of times the sealing material is applied and fired This leads to an increase in manufacturing cost, which is not preferable. On the other hand, the coarse powder having a too large particle diameter has a problem that the powder particles settle and separate when the powder is made into a paste, or when applied and dried. The particle diameter can be adjusted by removing the fine powder and coarse powder by operations such as classification. The average particle diameter is preferably 5 μm or more, more preferably 15 μm or more, and preferably 50 μm or less, more preferably 30 μm or less. The maximum particle size is preferably 150 μm or less, more preferably 100 μm or less. Therefore, for example, the average particle diameter can be 5 to 50 μm, the maximum particle diameter is 150 μm or less, or the average particle diameter is 5 to 30 μm, the maximum particle diameter is 100 μm, or the like.

  The glass composition for sealing of the present invention can be used for sealing ceramics and metals in the form of glass powder or mixed with ceramic powder. In sealing, it can be fired at 900 ° C. or lower after being applied to an object by printing or dispenser. In general, stainless steel (for example, SUS430) that can be obtained at low cost has a heat resistance temperature of about 900 ° C., and therefore, it is meaningful that the firing temperature is 900 ° C. or less.

  In order to improve the strength by finely adjusting the thermal expansion and promoting crystallization of the glass, zirconia powder, preferably partially stabilized zirconia powder, is used for the glass powder to reduce the flowability of the composition during sealing firing. It can be added in such an amount that it does not occur. The addition amount of zirconia powder or partially stabilized zirconia is ineffective if it is less than 0.01% by mass relative to the amount of glass powder, and if it exceeds 20% by mass, the flowability of the composition is lowered during sealing firing, and the flow is reduced. Since it inhibits, it is not preferable. Therefore, the addition amount of the partially stabilized zirconia is preferably 0.01 to 20% by mass, more preferably 0.01 to 5% by mass, and more preferably 0.01 to 1% by mass with respect to the amount of the glass powder. More preferably, it is as follows.

  In addition, for the same purpose as zirconia powder, a composition obtained by sealing and firing magnesia, forsterite, steatite, wollastonite and its precursor (that is, wollastonite when fired) is applied to glass powder. Can be added in such an amount that does not reduce the flowability of the liquid. If the total amount is less than 0.01% by mass with respect to the amount of the glass powder, there is no effect, and if it exceeds 5% by mass, the flowability of the composition during sealing firing is lowered, which is not preferable. Therefore, the total amount of magnesia, forsterite, steatite, wollastonite and its precursor is preferably 0.01 to 5% by mass, more preferably 0.01 to 1%, based on the amount of glass powder. It is not more than mass%, more preferably 0.01 to 0.5 mass%.

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

[Manufacture of glass bulk and glass powder]
Examples 1-13 and Comparative Examples 1-7:
The raw materials were prepared and mixed so as to have the glass compositions shown in Tables 1, 2 and 4, and the prepared raw materials were put in a platinum crucible and melted at 1400 to 1500 ° C. for 2 hours, and then glass flakes which were glass original materials were obtained. The glass flakes were put in a pot mill, and dry pulverization was performed until the average particle size became 30 to 40 μm. Thereafter, coarse particles were removed with a sieve having an opening of 106 μm to obtain glass powders of Examples and Comparative Examples.

Examples 14-17:
The raw materials were prepared and mixed so that the glass composition shown in Table 3 was obtained, and the prepared raw materials were put into a platinum crucible and melted at 1400 to 1500 ° C. for 2 hours, to obtain glass flakes as a glass raw material. The glass flakes were put in a pot mill, and dry pulverization was performed until the average particle size became 5 to 25 μm. Then, coarse particles were removed with a sieve having an opening of 106 μm to obtain a glass powder of Example.
〔Test method〕
About the glass powder of an Example and a comparative example, the average particle diameter of glass powder is measured with the following method, it calcinates, the flow diameter (diameter after a flow) by baking, the thermal expansion coefficient of a sintered compact, and a softening point Measured and evaluated.
(1) using an average particle size laser scattering type particle size distribution meter of glass powder was determined a value of D ₅₀ of the volume distribution mode.

(2) Flow diameter 5 g of glass powder obtained by pulverization was press-molded to a diameter of 20 mm and fired at 900 ° C. on a SUS430 substrate. The maximum outer diameter of the obtained sintered body was determined. A flow diameter of 20 mm or more was evaluated as ◎ (particularly good), 19 mm or more and less than 20 mm as ◯ (conformity), and less than 19 mm as x (nonconformity).

(3) Thermal expansion coefficient The sintered body obtained in the above (2) was cut out to about 5 × 5 × 15 mm to prepare a test body. The thermal expansion coefficient (α1) based on two points of 50 ° C. and 550 ° C. is obtained from the thermal expansion curve obtained when the temperature of the test body is increased from room temperature at 10 ° C./min using a TMA measuring device, and 50 A thermal expansion coefficient (α2) based on two points at 700 ° C. was obtained.
In addition, since the inflection point of the thermal expansion curve appears around 600 ° C., the difference between α2 and α1 (Δα = α2−α1) was calculated.
In the case where the coefficient of thermal expansion is less than 90 × 10 ⁻⁷ / ° C., there is a problem in matching properties with the metal and the cell, and therefore x (nonconformity) is written alongside the measured value.

(4) Softening point In the thermal expansion curve obtained in (3) above, the temperature at which the transition from expansion to contraction (the curve takes a maximum value) was determined and used as the softening point.
In the firing step of sealing the SOFC cell and the metal, firing may be repeatedly performed, and it is not preferable as a structural material that the sealing glass portion is softened at 900 ° C. or lower.
The softening point of 900 ° C. or higher is indicated by ○ (conformity), and the softening point of less than 900 ° C. is indicated by x (nonconformity) beside the measured value.

(5) Corrosiveness The appearance of the SUS surface at a site close to the edge of the sintered body obtained in (2) above was observed.
In addition, ○ (conformity) when there is substantially no difference between the SUS surface in the region close to the edge of the sintered body and the SUS surface in other regions, and the SUS surface in contact with the edge of the sintered body turns brown. What was done was made into x (nonconformity).

-As the wollastonite precursor, Zono Heidi (manufactured by Ube Material) was used.
-As the zirconia powder, 325 mesh under partially stabilized fused zirconia (containing 8% Y ₂ O ₃ ) was used.
-The magnesia powder used the electromelting magnesia of 200 mesh under.

  Tables 1 to 4 show the results. As can be seen from these tables, the glass compositions of Comparative Examples lacked any of the performance required for sealing glass, whereas the glass compositions of Examples 1 to 17 had a flow diameter during firing, All the performances required for the sealing glass were provided in both the thermal expansion coefficient and the softening point of the sintered body (crystal glass). Moreover, as shown in FIGS. 1-4 shown as an example, the thermal expansion curve (FIGS. 1 and 2 respectively) and the sintering of a comparative example (2 and 3) of the sintered body of Example (3 and 10) In the thermal expansion curves of the bodies (FIGS. 3 and 4 respectively), inflection points are seen in the thermal expansion curves of the sintered bodies of the comparative examples, and the coefficient of thermal expansion accompanying the temperature change is sharp across the inflection points. While there are fluctuations, no inflection points are found in the thermal expansion curves of the sintered bodies of the examples, and there is no rapid fluctuation of the thermal expansion coefficient due to temperature changes.

  The glass composition of the present invention is a solid oxide containing no alkali metal for sealing a metal and a ceramic, a metal and a metal, or a ceramic and a ceramic by contacting the metal and the ceramic and firing at 900 ° C. or less. It can be used as a sealing material suitable for a sealing part of a fuel cell (SOFC).

Thermal expansion curve of the sintered body of Example 3 Thermal expansion curve of the sintered body of Example 10 Thermal expansion curve of the sintered body of Comparative Example 2 Thermal expansion curve of the sintered body of Comparative Example 3

Claims (8)

Substantially free of alkali metals, converted to oxide,
SiO ₂ ... 10 to 30% by mass,
B ₂ O ₃ 20-30% by mass,
CaO ... 10 to 40% by mass,
MgO 15 to 40% by mass,
BaO + SrO + ZnO ... 0-10 mass%,
La ₂ O ₃ ... 0 to 5% by mass,
Al ₂ O ₃ ... 0 to 5 mass%, and RO ₂ ... 0 to 3 mass% (here, R represents Zr, Ti, or Sn).
A crystallized glass formed by firing glass powder made of this glass composition at a temperature of 900 ± 50 ° C. has a thermal expansion coefficient at 50 to 550 ° C. of 90 to 120 ×. A glass composition for sealing, which is 10 ⁻⁷ / ° C.   The glass composition of Claim 1 whose CaO content / MgO content is 0.4-2.0 by mass ratio. The glass composition according to claim 1 or 2, wherein the SiO ₂ content / B ₂ O ₃ content is 0.33 to 1.33 in terms of mass ratio. The glass according to any one of claims 1 to 3, wherein the total content of SiO ₂ and B ₂ O ₃ is 30 to 50% by mass, and the total content of CaO and MgO is 44 to 65% by mass. Composition.   The glass powder which consists of a glass composition in any one of Claim 1 thru | or 4 whose average particle diameter is 5-250 micrometers.   A glass / ceramic powder comprising 100 parts by mass of the glass powder comprising the glass composition according to claim 1 and 0.01 to 20 parts by mass of zirconia powder.   A glass powder comprising the glass composition of any one of claims 1 to 4 and one or more ceramic powders selected from the group consisting of magnesia, forsterite, steatite, wollastonite and precursors thereof. 1 or two or more ceramic powders selected from the group consisting of magnesia, forsterite, steatite, wollastonite and precursors thereof with respect to 100 parts by mass of the glass powder. Glass-ceramics powder containing 01-5 mass parts.   The glass-ceramic powder according to claim 6 or 7, wherein the glass powder has an average particle size of 5 to 250 µm.

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