WO2012133217A1 - Glass composition for sealing, and sealing material - Google Patents

Abstract

The objective of the present invention is to provide: a glass composition, which is useful for forming a glass ceramic that has thermal expansion characteristics suitable for sealing of a ceramic member and the like, and which exhibits good wettability with respect to the surface of the ceramic member and the like at the time of firing; and a sealing material. A glass composition for sealing, which has a compositional ratio wherein, in terms of oxides, SiO₂ is 14-21% by mass, Al₂O₃ is 0-12% by mass, B₂O₃ is 17-24% by mass, ZnO is 29-51% by mass and MgO is 7-16% by mass, and the like are provided in order to achieve the above-mentioned objective.

Description

Sealing glass composition and sealing material

The present invention relates to a glass composition for sealing and a sealing material, for example, a glass composition used for sealing between metal members, between ceramic members, or between a metal member and a ceramic member. And a sealing material containing glass powder made of the glass composition.

Conventionally, a sealing material containing glass powder is obtained by bonding metal members or ceramic members, or by bonding a metal member and a ceramic member, and part or all of the gap between these members. Are widely used for the purpose of sealing (hereinafter, ceramic members and metal members are collectively referred to as “ceramic members and the like”).
For example, ceramic members and the like are sometimes used in a high-temperature atmosphere in which a general resin undergoes thermal decomposition. Therefore, a gap between members used in such an atmosphere is sealed. For this, a sealing material containing glass powder is used.
In that case, for example, after filling the sealing material between the members to be sealed, the sealing material is heated to a temperature equal to or higher than the softening point of the glass powder contained in the sealing material. The gap is sealed with a sintered body of glass.
The sealing material used for such applications uses glass powder that can precipitate a crystalline phase by firing, and is a member made of a fired body called glass ceramics in which the crystalline phase is precipitated in glass. It is done to seal between.

This type of glass ceramics is generally excellent in that it has little transformation of crystal phase when fired and has high strength, and is widely used as a material suitable for sealing ceramic members and the like. Yes.
For example, Patent Document 1 below describes a glass composition for sealing between members made of an Fe—Ni—Co alloy exhibiting the same thermal expansion coefficient as a member made of ceramics.
However, since the invention described in Patent Document 1 below has a low SiO ₂ content and a low crystallization peak temperature, there is a possibility that wetting of the ceramic after glass softening becomes insufficient.
Therefore, with the glass composition described in Patent Document 1, it is difficult to perform highly reliable sealing on a ceramic member or the like.
Moreover, in the glass composition of patent document 1, unless the temperature increase rate is made quick, the fluidity | liquidity at the time of baking will become inadequate easily, and it will be easy to produce problems, such as insufficient sealing.

Moreover, the following patent document 2 describes a glass composition used for sealing alumina ceramic members.
However, the glass composition described in the following Patent Document 2 is easy to obtain a fired body having a small coefficient of thermal expansion at 30 to 550 ° C., and after firing, temperature changes such as temperature rise and cooling occur in a temperature range having a small coefficient of thermal expansion. If it occurs, stress due to the difference in thermal expansion coefficient is likely to be generated in the vicinity of the interface between the alumina ceramic member and the glass ceramic, which may cause peeling.
Moreover, since the glass composition described in Patent Document 2 has a high BaO content and crystallization after firing is likely to be insufficient, the ratio of the glass phase (residual glass phase) present in the glass ceramic is increased. The influence of the characteristics of the residual glass phase on the whole becomes large.
That is, the difference between the thermal expansion coefficient at 30 to 500 ° C. and the thermal expansion coefficient at 30 to 600 ° C. tends to increase depending on the transition point of the remaining glass phase. When the cycle is applied, microcracks are generated in the vicinity of the interface between the alumina ceramic member and the glass ceramic, which may reduce the sealing performance.

Furthermore, Patent Document 3 below describes a glass composition for sealing between a gas sensor element composed of zirconia or alumina ceramics and insulating glass.
However, since this glass composition also contains a large amount of BaO, crystallization after firing tends to be insufficient, and the difference between the thermal expansion coefficient at 30 to 500 ° C. and the thermal expansion coefficient at 30 to 600 ° C. is increased, resulting in sealing properties. May be reduced.

Japanese Laid-Open Patent Publication No. 58-204837 Japanese Unexamined Patent Publication No. 10-236844 Japanese Unexamined Patent Publication No. 2003-4694

In view of the above-described problems, the present invention is useful for forming glass ceramics having thermal expansion characteristics suitable for sealing ceramic members and the like, and on the surface of ceramic members and the like during firing. The object is to provide a glass composition exhibiting good wettability and a sealing material. *

The present invention relating to a glass composition for sealing to solve the above-mentioned problems is, in terms of oxides, SiO ₂ : 14 to 21% by mass, Al ₂ O ₃ : 0 to 12% by mass, B ₂ O ₃ : 17 to It has a composition ratio of 24% by mass, ZnO: 29 to 51% by mass, and MgO: 7 to 16% by mass.

Further, the invention according to the sealing material for solving the problem contains a glass powder, a sealing material for use in sealing is fired, the glass powder, in terms of oxide, SiO ₂ : 14 to 21% by mass, Al ₂ O ₃ : 0 to 12% by mass, B ₂ O ₃ : 17 to 24% by mass, ZnO: 29 to 51% by mass, MgO: 7 to 16% by mass It is characterized by being contained in.

According to the present invention, a glass ceramic that exhibits a thermal expansion coefficient close to that of a ceramic member or the like and does not show a large difference between a thermal expansion coefficient at 30 to 500 ° C. and a thermal expansion coefficient at 30 to 600 ° C. is formed. In addition, it is possible to provide a sealing glass composition that exhibits good wetting with respect to the surface of a ceramic member or the like during firing, and a sealing material suitable for sealing a ceramic member or the like. Can be provided.

The glass composition for sealing according to the present invention preferably has a property of precipitating SiO ₂ —ZnO-based and MgO—B ₂ O ₃ -based crystal phases during firing.
According to this preferred embodiment, the glass ceramic obtained by firing the sealing glass composition of the present invention can be more reliably made to have a thermal expansion coefficient close to that of a ceramic member or the like.

In the glass composition of the present invention, the difference between the thermal expansion coefficient at 30 to 500 ° C. and the thermal expansion coefficient at 30 to 600 ° C. of the crystallized glass formed by firing is 9.0 × 10 ⁻⁷ / ° C. The following is preferable.
According to such a preferable aspect, the sealing property with a ceramic member or the like can be further improved.

In the glass composition of the present invention, the difference between the glass softening point (Ts) and the crystallization peak temperature (Tx) is preferably 130 ° C. or higher.
According to such a preferable aspect, since the fluidity | liquidity at the time of baking can be made favorable, a sealing operation | work can be made easy.

The glass composition of the present invention preferably has a thermal expansion coefficient at 30 to 550 ° C. of the glass ceramic formed by firing of 60 to 70 × 10 ⁻⁷ / ° C.
According to such a preferred embodiment, it is possible to exhibit excellent sealing properties for an alumina ceramic member having a thermal expansion coefficient of 60 to 80 × 10 ⁻⁷ / ° C. or the like.

Furthermore, the sealing material of the present invention contains ceramic powder together with the glass powder made of the glass composition in order to adjust the strength and thermal expansion coefficient of the fired body obtained by firing the sealing material. In this case, the ratio of the ceramic powder in the total amount of the glass powder and the ceramic powder is preferably more than 0% by mass and 5% by mass or less.
By including such ceramic powder, the strength and thermal expansion coefficient of the fired body (composite of glass ceramics and ceramic powder) after firing can be easily adjusted.

Flow test result of the calcined body (good). Flow test result of the calcined body (defect).

The sealing glass composition and sealing material of the present invention will be described below.
As a sealing material of this embodiment, what was comprised only by the glass powder which grind | pulverized the glass raw material which consists of a predetermined glass composition for sealing, or the thing containing ceramic powder with this glass powder is mentioned, for example. .
It is important that this glass powder is contained in the sealing material so as to have the following component composition in that a predetermined thermal expansion coefficient can be imparted to the crystallized glass after firing.

Specifically, the glass composition for sealing according to the present embodiment is SiO ₂ : 14 to 21% by mass in terms of oxide, Al ₂ O ₃ : 0 to 12% by mass, B ₂ O ₃ : 17 to 24% by mass. %, ZnO: 29 to 51% by mass, and MgO: 7 to 16% by mass.

Below, each component of the glass composition for sealing is demonstrated.
In the glass composition for sealing of this embodiment, SiO ₂ is a glass network forming component, which improves the stability of the glass during the production of the glass base, and is SiO ₂ —ZnO-based (willemite, etc.) It is an essential component effective for producing the crystals.

In addition, when crystals are precipitated in the glass raw material, the glass powder obtained by pulverizing the glass has a faster start of crystallization at the time of firing, so that the fluidity of the melt is early in the stage after firing. It is likely that the surface of a ceramic member or the like that performs sealing will be insufficiently wet.
In the glass composition for sealing of the present embodiment, the above range is defined for the content of SiO ₂ is based on such a viewpoint, and the above lower limit is defined. If the content of SiO ₂ is less than the above range, the stability of the glass is lowered, and when the glass powder is fired, the start of crystallization is accelerated, and the obtained fired body is not sufficiently bonded to the surface of the ceramic member or the like. This is because of fear.
In addition, the upper limit as described above is determined when the SiO ₂ content exceeds the above range, the phase transition between the low-temperature crystal phase (α) and the high-temperature crystal phase (β) This is because SiO ₂ -based (such as cristobalite) crystals that occur in a temperature range in which manufactured members are generally used are likely to precipitate.
When there is a transition of the crystal phase (that is, α → β or β → α transition), for example, when there is a transition at 250 ° C., heating or cooling with the temperature of 250 ° C. sandwiched after firing When added to the above, a rapid volume expansion or contraction occurs, and there is a risk of generating microcracks in the glass ceramic obtained by firing or the ceramic member sealed with the glass ceramic.

Whether such volume expansion or contraction occurs can be confirmed using a thermomechanical analysis (TMA) apparatus. For example, the glass ceramic made of the sealing glass composition of the present embodiment is 300 It is preferable that an inflection point is not observed on the TMA curve in a temperature range of ° C or lower.
As for the “inflection point” observed in the temperature range of 300 ° C. or less, if the thermal expansion coefficient at 10 ° C. before and after a certain temperature has changed by 20% or more, the inflection point is indicated on the TMA curve. Can be confirmed.

From the above, the content of SiO ₂ in the sealing glass composition of the present embodiment is usually 14% by mass or more, preferably 14.5% by mass or more, more preferably 15% by mass or more. The
Further, the content of SiO ₂ is usually 21% by mass or less, preferably 19.5% by mass or less, more preferably 19% by mass or less.
That is, the content of SiO ₂ in the sealing glass composition of this embodiment is usually 14 to 21% by mass, preferably 14.5 to 20% by mass, and preferably 15 to 19% by mass. It is particularly preferable.

In the glass composition for sealing of this embodiment, Al ₂ O ₃ is a component useful for improving the stability during production of the glass raw material, and for adjusting the crystallization start temperature and maintaining the adhesive force with the ceramic member and the like. It is.
Although Al ₂ O ₃ is an optional component, it is a useful component for forming Al ₂ O ₃ —ZnO-based (garnite, etc.) crystals in glass ceramics.
Since the Al ₂ O ₃ —ZnO-based (garnite, etc.) crystal has a thermal expansion coefficient close to that of alumina or zirconia, the sealing material according to this embodiment is used for sealing alumina members or zirconia members. In some cases, it is preferable to form the sealing material in a glass ceramic obtained by firing.
However, if Al ₂ O ₃ is excessively contained in the glass composition for sealing, there is a risk that the linearity of the thermal expansion coefficient with respect to a temperature change may be caused as a result of leaving many glass phases after firing.
For these reasons, the content of Al ₂ O ₃ in the sealing glass composition of the present embodiment is usually 0 to 12% by mass, but more preferably 1 to 10% by mass.

In the glass composition for sealing of the present embodiment, B ₂ O ₃ is a glass network forming component and an essential component for improving the stability of the glass during the production of the glass base.
B ₂ O ₃ is also an effective component for precipitating MgO—B ₂ O ₃ -based (such as suanite) crystals in the fired body (glass ceramic) when the sealing material of the present embodiment is fired. It is.
The lower limit as described above on the content of B ₂ O ₃ is defined, in the B than ₂ content of O ₃ is 17% by mass, decreases the stability of the glass, crystals in the firing of the glass powder It is because there is a possibility that fluidization may be started earlier and fluidity may be reduced.
In addition, the upper limit as described above is determined when the content of B ₂ O ₃ exceeds 24% by mass, and the glass phase that does not crystallize remains in the fired glass ceramic. This is because the linearity of the thermal expansion coefficient with respect to temperature change may be reduced.
Therefore, the content of B ₂ O ₃ is usually 17% by mass or more, preferably 18% by mass or more, more preferably 19% by mass or more.
Further, the content of B ₂ O ₃ is usually 24% by mass or less, preferably 23% by mass or less, more preferably 22% by mass or less.
That is, the content of B ₂ O ₃ in the sealing glass composition of the present embodiment is usually 17 to 24% by mass, preferably 18 to 23% by mass, and preferably 19 to 22% by mass. It is particularly preferable.

In the glass composition for sealing of the present embodiment, ZnO is an essential component effective for producing crystals having few transformations such as phase transition such as SiO ₂ —ZnO-based and Al ₂ O ₃ —ZnO-based (such as garnite). .
In addition, ZnO is an effective component for suppressing Al ₂ O _{3 from} remaining in the glass phase by generating Al ₂ O ₃ —ZnO-based crystals.
The lower limit as described above is determined for the content of ZnO. If the content of ZnO is less than 29% by mass, the degree of crystallinity in the fired body (glass ceramic) after firing is not sufficient. This is because the residual ratio of the glass phase to the crystal phase may be increased.

In addition, the upper limit as described above is determined for the content of ZnO. If the content of ZnO exceeds 51% by mass, the stability during the production of the glass raw material is reduced, and the glass powder is fired. This is because there is a possibility of reducing the flowability at the time.
In addition, when ZnO is excessively contained, SiO ₂ —ZnO-based crystals are precipitated, and the thermal expansion coefficient is 60 × 10 ⁻⁷ / ° C. or more and 70 × 10 ⁻⁷ which is suitable for sealing ceramic members and the like. There is a risk of causing the temperature to fall outside the range of less than / ° C.

From the above, the content of ZnO in the sealing glass composition of this embodiment is usually 29% by mass or more, preferably 32% by mass or more, more preferably 34% by mass or more.
The ZnO content is usually 51% by mass or less, preferably 50% by mass or less, and more preferably 49% by mass or less.
That is, the ZnO content in the present embodiment is usually 29 to 51% by mass, preferably 32 to 50% by mass, and more preferably 34 to 49% by mass.

In the sealing glass composition of the present embodiment, MgO is an essential component effective for precipitating MgO—B ₂ O ₃ -based highly expansive crystals in glass ceramics obtained by firing a sealing material. .
The lower limit as described above is determined for the content of MgO because, if the content of MgO is less than 7% by mass, sufficient crystal precipitation does not occur in the fired glass ceramic, and the glass with respect to the crystalline phase Since the residual ratio of the phase is increased, it may be difficult to impart good heat resistance to the glass ceramic.
On the other hand, when the MgO content is less than 7% by mass, the generation of MgO—B ₂ O ₃ based crystals becomes insufficient, and the thermal expansion coefficient of the glass ceramic is 60 × 10 which is suitable for sealing ceramic members and the like. ^There is a risk that it will be outside the range of ⁻⁷ / ° C. to 70 × 10 ⁻⁷ / ° C.
In addition, the upper limit as described above is determined when the MgO content exceeds 16% by mass, the stability during the production of the glass base material is lowered, and the glass when the sealing material is fired. This is because the melt does not have sufficient fluidity and it is difficult to perform good sealing.
Further, when MgO is excessively contained, MgO—B ₂ O ₃ -based crystals are generated more and the thermal expansion coefficient may become higher than necessary.

From the above, the content of MgO in the sealing glass composition of the present embodiment is usually 7% by mass or more, preferably 9% by mass or more, and more preferably 10% by mass or more.
The content of MgO is usually 16% by mass or less, preferably 15% by mass or less, and more preferably 14% by mass or less.
That is, the content of MgO in the present embodiment is usually 7 to 16% by mass, preferably 9 to 15% by mass, and more preferably 10 to 14% by mass.

In addition, the sealing material which concerns on this embodiment does not need to correspond by the composition ratio in conversion of an oxide in all the glass powders to contain, and two or more glass powders from which a component ratio differs may be blended.
In this case, as long as the overall component ratio matches the above composition ratio, a part of the glass powder can be formed of a glass composition other than the above composition ratio.

Furthermore, in the present embodiment, if the above relationship is satisfied between the contents of SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , ZnO, and MgO in the sealing glass composition, Neutral components that do not significantly affect the physical properties of the resulting glass raw material or crystallized glass can be added as long as the effects of the present invention are not significantly impaired. In this case, it is within the scope of the present invention.

Examples of the neutral component include CaO, SrO, BaO, Y ₂ O ₃ , La ₂ O ₅ , TiO ₂ , ZrO ₂ , and CeO ₂ .
If the total weight of these components is 2% by mass or less, even if they are usually contained as components of the glass composition, they have a significant adverse effect on the crystallized glass during firing for sealing or after firing. Not give.
On the other hand, P ₂ O ₅ or the like makes it easier to stabilize the glass state when producing the glass raw material, but on the other hand, it causes phase separation in the crystallized glass after firing and substantially reduces acid resistance. It is preferable not to contain.
Further, transition metal elements belonging to Group 5 to Group 11, especially Cu, etc., tend to improve the electrical conductivity of glass at high temperatures, so that it is a sealing material for solid oxide fuel cells that require insulation. Is an unsuitable component, and it is preferable not to contain substantially when a sealing material is utilized for this kind of use.
Further, since alkali metals such as Na and K also show a tendency to improve electrical conductivity in a high temperature range, it is preferable that they are not substantially contained when the sealing material is used for this kind of application. .

Here, the expression “substantially not contain” is not intended to deny the case where it is contained at the impurity level in this specification, for example, a raw material for producing a glass raw material, etc. It is intended that the inclusion is acceptable if the level is contained as an impurity.
More specifically, the components as described above are less likely to be a problem even if they are contained if their total amount is 1000 ppm or less in terms of oxide, and correspond to the case where they are not substantially contained.
However, in the sense of more reliably preventing the possibility of causing the above problems, it is preferable that the content of at least the Cu component is less than 100 ppm in terms of oxides, from Group 5 to Group 11 The total of transition metal element components corresponding to the above is more preferably 100 ppm or less, and the total is particularly preferably 30 ppm or less.

In the present invention, the glass composition composed of the components as described above has a difference (Tx−Ts) between the crystallization peak temperature (Tx) and the softening point (Ts) of 130 ° C. or more. It is preferably adjusted.
The difference between the crystallization peak temperature and the softening point (Tx−Ts) is preferably 130 ° C. or more. If this difference is less than 130 ° C., the fluidity during firing is insufficient, and a dense fired body is obtained. This is because there is a fear that a gap may be formed between the sintered object such as an alumina ceramic member or a zirconia ceramic member and the fired body.
In order to prevent such a fear more reliably, the difference (Tx−Ts) is preferably 140 ° C. or higher.
The upper limit of the difference (Tx−Ts) is not particularly limited, but is usually 200 ° C.
The crystallization peak temperature (Tx) is, for example, higher than the softening point (Ts) by performing differential thermal analysis (DTA) on a sample of about 40 mg at a rate of temperature increase of about 10 ° C./min. And it can obtain | require by measuring the peak temperature of the exothermic peak seen initially.
The glass composition for sealing according to the present embodiment is more suitable for sealing applications such as a ceramic member by having such characteristics.

Next, the glass powder and the sealing material containing the glass powder will be described.
In order to form glass powder with the sealing glass composition as described above, for example, a metal oxide as a raw material is prepared and mixed, and the mixture is melted at a temperature of 1300 to 1450 ° C., for example. The molten glass may be cooled without being crystallized, and the glass raw material obtained by the cooling may be dry pulverized.

Further, a general sealing material is required to have high fluidity during firing because the glass powder once shrinks during firing and is required to wet the surface of a ceramic member while softening and flowing.
For this purpose, the particle size is adjusted according to the dry pulverization conditions, the average particle size is preferably 5 to 50 μm, and the maximum particle size is preferably 200 μm or less.
For example, if the average particle size is less than 5 μm, the proportion of fine powder increases, and there is a possibility that sufficient fluidity to wet the surface of a ceramic member or the like may not be exhibited.
On the other hand, when the average particle size exceeds 50 μm, crystals are not sufficiently precipitated in the glass ceramic after sealing, and the residual ratio of the glass phase to the crystal phase is increased, and sufficient heat resistance may not be obtained.

Here, when the particle size is too small, crystallization starts earlier, the flowability of the melt at the time of sealing firing may decrease, and flow inhibition may occur, and the number of times the sealing material is applied and fired It is necessary to increase the manufacturing cost of the product manufactured using the sealing material.
On the other hand, a coarse powder having an excessively large particle size has a problem that the powder particles settle and separate when the powder is made into a paste or when applied and dried, and the crystallization is uneven and insufficient. May cause insufficient strength.
From the above, it is preferable to adjust the particle size by removing fine powder and coarse powder by operations such as classification.
That is, the glass powder contained in the sealing material according to the present embodiment is classified so that the maximum particle size is 200 μm or less, more preferably 150 μm or less, while the average particle size is 5 μm or more and 50 μm or less. Is preferably included in the sealing material.

This glass powder can be used alone or together with ceramic powder (ceramic filler) to form a sealing material.
By containing this ceramic powder, it is possible to finely adjust the coefficient of thermal expansion and improve the strength of the glass after firing.
However, this ceramic powder is preferably contained in the sealing material in such a content that does not greatly affect the flowability during firing.
That is, when the total amount of the glass powder and the ceramic powder is 100% by mass, if the ceramic powder content exceeds 5% by mass, the flowability may be hindered. It is preferable to be over 0% by mass and 5% by mass or less.
However, if the content of the ceramic powder is less than 0.01% by mass, the effect may not be expected. Therefore, the content of the ceramic powder in the total amount of the glass powder and the ceramic powder is 0.01 to 5% by mass. The content is preferably 0.03 to 5% by mass. Further, it is particularly preferably 0.03 to 3% by mass.

Examples of the ceramic filler include, but are not limited to, powders of alumina, quartz glass, zirconia, magnesia, and the like.
The average particle size of the ceramic filler is preferably 20 μm or less, more preferably 5 μm or less, even more preferably 3 μm or less, and the maximum particle size is preferably 106 μm or less, more preferably 45 μm or less, and even more preferably 22 μm or less. is there.

Note that the sealing material according to the present embodiment is not limited to the use of the glass powder alone, but a paste in which the glass powder and ceramic powder (ceramic filler) are dispersed in a binder or a slurry in which a solvent is dispersed. In a form, for example, it is used by applying to a sealing object by printing or by a dispenser.
In particular, since the sealing material according to this embodiment uses glass powder composed of the glass composition as described above, the thermal expansion coefficient of the fired body after firing is suitable for sealing ceramic members and the like. It becomes a suitable state.

Specifically, in the glass composition as described above, the inflection point of the thermal expansion coefficient due to the remaining glass in the glass ceramic after firing appears from 520 ° C. to less than 600 ° C. In order to exhibit the wearability, the difference (α ₂ −α ₁ ) between the thermal expansion coefficient (α1) at 30 to 500 ° C. and the thermal expansion coefficient (α ₂ ) at 30 to 600 ° C. is 0 to 9.0 × 10 ⁻ It is preferably ⁷ / ° C.
30 to the and the difference in thermal expansion coefficient (alpha ₁₎ and the thermal expansion coefficient of _{30 ~ 600 ℃ (α 2)} (α 2 -α 1) is within this range at 500 ° C., thermal expansion When the difference in coefficient exceeds 9.0 × 10 ⁻⁷ / ° C., glass ceramics formed by firing the sealing material when a heating or cooling thermal cycle is applied between 500 ° C. and 600 ° C. This is because there is a possibility of generating microcracks in the ceramic member sealed with the glass ceramic, and if the difference in thermal expansion coefficient is negative, crystallization is considered to be insufficient. Because.
Further, when the thermal expansion coefficient at 30 to 550 ° C. of the crystallized glass after firing is 60 to 70 × 10 ⁻⁷ / ° C., the thermal expansion coefficient at 30 to 500 ° C. and the thermal expansion coefficient at 30 to 600 ° C. A thermal expansion coefficient suitable for sealing a ceramic member or the like having a thermal expansion coefficient of 60 to 80 × 10 ⁻⁷ / ° C. is preferable.

Moreover, after mixing the glass powder and the mixture of the glass powder and ceramic powder with a molding aid, dry press molding is performed, and a molded body that has been pre-sintered at a temperature near the softening point of the glass is used as a sealing material. can do.
The pre-sintered molded body is also called a pre-fired body and can be handled as a part, so that it has excellent handling properties and is suitable as a sealing material.
The calcined body is incorporated into a ceramic member or the like to be sealed, and is softened and fluidized by being fired, and then crystallized to exhibit excellent performance as a sealing material.
Hereinafter, the calcined body will be described.

The average particle size of the glass powder for producing the calcined body is preferably in the range of 6 μm to 50 μm, and in the range of 6.5 μm to 25 μm, from the viewpoint of workability in the subsequent steps of granulation and dry press molding. Further preferred.
In other words, if the average particle size is too fine, the calcined body may not exhibit sufficient fluidity during sealing firing, and also tends to cause uneven density during dry press molding, resulting in dimensional variation of the calcined body. There is a risk of causing.
On the other hand, if the average particle size is too large, the yield of the granulated powder may be reduced.

A granulated powder suitable for dry press molding can be obtained by mixing the glass powder with a binder resin such as an acrylic resin as a molding aid.

A molded body having a desired shape can be obtained by dry press molding using this granulated powder.

By holding this molded body at a temperature not lower than the temperature at which the binder resin thermally decomposes and not higher than the glass transition point, the binder resin is removed, and then temporary sintering is performed at a temperature near the softening point of the glass. A fired body is obtained.

In the calcined body thus obtained, if contaminants such as salt in human sweat or inorganic powder adhering to the resin gloves as a lubricant adhere to the surface of the calcined body, these are sealed. It becomes a nucleating agent for crystallization of glass at the time of firing and impedes the flow of glass.
If it does so, wetting with the member to adhere, such as a ceramic member, will deteriorate, it will be easy to exfoliate from the member, and there is a possibility that the performance as a sealing material may deteriorate remarkably.

Moreover, when the surface roughness of the calcined body is large, contaminants are likely to adhere, and the flow of the glass is likely to be hindered.
In other words, when the surface roughness of the calcined body is small, contaminants hardly adhere to the calcined body, and the flow of the glass is hardly inhibited.
That is, a calcined body having stable sealing performance can be obtained by adjusting the average particle diameter of the glass powder, conditions for pre-sintering, and controlling the surface roughness.
For this reason, the surface roughness of the calcined body of the present embodiment is preferably 0.5 μm or less, and more preferably 0.1 μm or less.

As a method of confirming the performance of the calcined body thus obtained, for example, a flow test in which the calcined body is fired at about 900 ° C. on a substrate made of ceramics such as alumina and the appearance after firing is observed. There is.
When the calcined body is free from contaminants, the flow of the glass is not hindered, and the shape after the flow becomes a normal state close to a hemisphere as shown in FIG.
Moreover, it can be assumed that the height after flow (flow height) is low and sufficient sealing performance is obtained.
On the other hand, when the contaminant is adhered, the flow of the glass is hindered and a normal shape cannot be obtained as shown in FIG.
Moreover, when the contaminant has adhered, flow height becomes high and sealing performance becomes inadequate.

Although not described in detail here, the technical matters relating to the glass powder and other materials to be included in the sealing material, production conditions, etc., are within the scope not significantly impairing the effects of the present invention. The present invention can also be employed, and the present invention is not limited to the above examples.

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

[Manufacture of glass bulk and glass powder]
Examples 1 to 9 and Comparative Examples 1 to 10
The raw materials were prepared and mixed so as to have the glass compositions shown in Tables 1 and 2, and the prepared raw materials were put in a platinum crucible and melted at 1300 to 1450 ° C. for 1 hour to obtain glass flakes as a glass raw material.
The glass flakes were put in a pot mill and pulverized while adjusting the average particle size to 5 to 50 μm, and then coarse particles were removed with a sieve having an opening of 106 μm. Examples 1 to 9 and Comparative Examples 1 to Ten glass powders were used.
For Example 6, alumina powder (average particle size 2 μm) was added to the glass powder, and the mixture was evaluated.
Comparative Example 9 is a glass powder having a composition range of Patent Document 3, and Comparative Example 10 has the same composition as the glass powder of Example 2 of Patent Document 2.

〔Test method〕
About the glass powder of the Example and the comparative example, the following method measured the average particle diameter of the glass powder, the softening point, and the crystallization peak temperature, it baked and evaluated the thermal expansion coefficient and the flow diameter.
(1) using an average particle size of a laser scattering particle size distribution meter of glass powder (manufactured by Nikkiso Co., Ltd. Microtrac MT3000), it was determined a value of D ₅₀ of the volume distribution mode.

(2) Softening point, crystallization peak temperature Approximately 40 mg of glass powder is filled in a platinum cell, and the temperature is increased from room temperature to 10 ° C./min using a DTA measuring device (Thermo Plus Thermo Plus TG8120). Ts) and crystallization peak temperature (Tx) were measured. When (Tx−Ts) is less than 130 ° C., there is a possibility of causing a problem in fluidity.

(3) Coefficient of thermal expansion The obtained glass powder was molded by a dry press and then fired at 900 ° C.
The fired body obtained by this firing was cut out to about 5 × 5 × 15 mm to prepare a test body.
Using a TMA measuring device (Thermo Plus Thermo Plus TMA8310), the thermal expansion curve was measured when the specimen was heated from room temperature at 10 ° C./min.
From this thermal expansion curve, the coefficient of thermal expansion was determined from the length of the specimen at 550 ° C., based on the length of the specimen at 30 ° C. This value was defined as the thermal expansion coefficient (α) at 30 to 550 ° C.
That is, the thermal expansion coefficient at 30 to 550 ° C. was determined from the slope of a straight line connecting two points of 30 ° C. and 550 ° C. in this thermal expansion curve, and this was used as the thermal expansion coefficient (α) of this specimen.
If the coefficient of thermal expansion is less than 60 × 10 ⁻⁷ / ° C. or more than 70 × 10 ⁻⁷ / ° C., it may cause a problem in matching the thermal expansion characteristics with a ceramic member. An “x” is also written next to the mark.
Further, since the inflection point of the thermal expansion coefficient due to the remaining glass in the crystallized glass after firing appears from 520 ° C. to less than 600 ° C., the thermal expansion coefficient at 30 to 500 ° C. and the thermal expansion coefficient at 30 to 600 ° C. The difference was calculated.
When the difference in thermal expansion coefficient exceeded 9.0 × 10 ⁻⁷ / ° C., “x” (nonconformity) was written alongside the measured value.
Further, it was confirmed by TMA curve whether or not the inflection point of the thermal expansion coefficient due to the crystal having a phase transition appears at 300 ° C. or lower.
If the inflection point is confirmed at 300 ° C or lower, there is a possibility of causing a problem in matching the thermal expansion characteristics with a ceramic member or the like. Therefore, “Yes” is indicated. did.

(4) Sealability (flowability)
5 g of the glass powder was formed into a cylindrical shape having a diameter of 20 mm, placed on an alumina substrate, fired at 900 ° C., and the maximum outer diameter of the fired body obtained was measured. When the flow diameter (maximum outer diameter) is 19.5 mm or less, it is determined that the fluidity sufficient to wet the surface of the alumina ceramic member is not provided, and an “x” is placed beside the measured value. Also written.
The results are shown in Tables 1-2.

　

　

The results are shown in Tables 1-2.
As can be seen from these tables, the sealing materials of the examples are flow characteristics that are indicators of wettability to the surface of ceramic members and the like, and thermal expansion coefficients and thermal expansion coefficients that are indicators of suitability for thermal expansion characteristics. The difference between the crystallization peak temperature and the softening point is an index indicating whether reliable sealing can be easily performed without generating a gap or the like at the time of sealing. Excellent results are also obtained in (Tx−Ts).
On the other hand, the sealing material of the comparative example has not obtained a good value in any item.
Also from this, according to the present invention, it is useful for forming glass ceramics having a thermal expansion characteristic suitable for sealing ceramic members and the like, and good for the surface of ceramic members and the like during firing. It can be seen that a glass composition and a sealing material exhibiting wettability are provided.

[Production of calcined body]
Next, preparation of a calcined body using the glass composition of Example 4 in Table 1 will be described.
What weighed each raw material was sufficiently mixed and melted in the range of 1300 ° C. to 1450 ° C. to obtain glass flakes.
The glass flakes were pulverized using a pot mill to obtain glass powder having an average particle size of 8 to 23 μm.

Next, an acrylic resin was added to and mixed with glass powder to obtain a granulated powder suitable for dry press molding.

Using this granulated powder, a molded body having a desired shape such as a cylinder, a prism, or a ring having a diameter or side of 5 to 25 mm and a thickness of 0.5 to 10 mm was obtained by dry press molding.

Hold this molded body at a temperature above the temperature at which the acrylic resin thermally decomposes and below the glass transition point, sufficiently remove the acrylic resin, and then perform preliminary sintering at a temperature near the softening point of the glass. A calcined body was obtained.

〔Test method〕
By the above method, the surface roughness of the calcined body produced by changing the pre-sintering temperature condition and the change in fluidity with respect to contamination were evaluated.
The pre-sintering temperature conditions are four levels of Condition 1, Condition 2, Condition 3, and Condition 4. Condition 1 is the lowest, and is increased in this order, and Condition 4 is the highest.
That is, with condition 2 near the softening point as a reference, condition 1 was set at reference −5 ° C., condition 3 was set at reference + 5 ° C., and condition 4 was set at reference + 10 ° C.
Note that this pre-sintering temperature condition may vary depending on the furnace used.

(1) Surface Roughness Using an Olympus laser microscope PLS-3500, a 3D image of the surface of the calcined body was captured in the confocal mode, and the arithmetic average roughness Ra was determined by image analysis.

(2) Change in fluidity with respect to contamination A flow test of the calcined body was performed in a state after pre-sintering, and the flow height was measured.
Next, the calcined body was immersed in 1% saline and dried, and then the same flow test was performed to measure the flow height.
The change rate from the flow height after pre-sintering was determined as the deterioration rate from the following equation.

Deterioration rate = (H1-H0) / (H0)
(However, “H0” is the flow height of the calcined body not immersed in saline, and “H1” is the flow height of the calcined body immersed in 1% saline and dried.)

NaCl is a representative contaminant that becomes a crystallization nucleating agent that inhibits the flow of glass during sealing firing.
When the contaminants are attached to the calcined body by dipping and drying in a 1% saline solution, the flow of the glass is inhibited and the flow height is increased.
And, from the deterioration rate after pre-sintering, it is possible to determine the resistance to the flowable contaminants of the glass, that is, the difficulty of being affected by the contaminants, and it can be said that the greater the deterioration rate, the more susceptible to the contaminants. .
A deterioration rate of 0.1 or less was evaluated as “AA”, a value exceeding 0.1 but less than 0.3 was determined as “A”, and a value of 0.3 or more was determined as “F”.
The above results are shown in Table 3.

　

In the above evaluation, it was confirmed that Ra was in the range of 0.02 to 0.93 μm depending on the presintered state.
As a result, in the case of Ra = 0.93 μm, the deterioration rate was as large as 0.48, the flow height showed a considerable change depending on the presence or absence of contaminants, and it was confirmed that the resistance to contaminants was low.
On the other hand, when Ra = 0.40 μm, the deterioration rate was 0.21, and it was found that the resistance to contaminants was improved.
Furthermore, when Ra is 0.1 μm or less, the deterioration rate is 0.03 or less, and it has been found that the flowability of the glass during sealing firing hardly deteriorates even if contaminants adhere.

As described above, in order to obtain a calcined body having stable glass flowability during sealing firing, and consequently obtaining a calcined body having stable sealing performance, the surface roughness of the calcined body is adjusted by adjusting the production conditions. It can be seen that the thickness Ra should be 0.5 μm or less, preferably 0.10 μm or less.
Here, the adjustment of the surface roughness was made by adjusting the pre-sintering conditions, but other adjustments by the average particle diameter of the powder glass are also possible. The surface roughness can be reduced as the average particle size is reduced in the range of 5 to 25 μm.
For example, if the pre-sintering temperature is set to a higher condition, the powder glass is softened, contracted, and flowed, and the desired calcined body shape and dimensions cannot be obtained. More determined.

The glass composition for sealing of the present invention can be suitably used for sealing between the members by bringing the glass composition into contact with a metal member or a ceramic member and firing at a temperature of about 900 ° C., for example.
Moreover, granulation, a dry press, and temporary sintering can be performed using the glass composition for sealing of this invention, and a calcined body can be obtained. This calcined body is easy to handle and can be suitably used by sealing between the members.
As a specific application, for example, a sealing material for sealing a sealing portion such as a ceramic sensor or a fuel cell can be used.

Claims (7)

1. In terms of oxides, SiO ₂ : 14 to 21% by mass, Al ₂ O ₃ : 0 to 12% by mass, B ₂ O ₃ : 17 to 24% by mass, ZnO: 29 to 51% by mass, MgO: 7 to 16% by mass A glass composition for sealing, which has a composition ratio of%.
2. _{2. The} glass composition for sealing according to claim 1, wherein the glass composition is fired to precipitate glass crystals of SiO ₂ —ZnO and MgO—B ₂ O ₃ .
3. The glass ceramic, 30-500 thermal expansion coefficient in ° C. (alpha ₁₎ and 30 thermal expansion coefficient at ~ 600 ℃ (α ₂₎ the difference between (α ₂ -α ₁₎ is 0 ~ 9.0 × ^{10 -7} The glass composition for sealing according to claim 2, which is a glass ceramic that is / ° C.
4. The glass composition for sealing according to claim 2 or 3, wherein the difference between the glass softening point (Ts) and the crystallization peak temperature (Tx) is 130 ° C or higher.
5. The glass composition for sealing according to any one of claims 2 to 4, wherein the glass ceramic has a thermal expansion coefficient at 30 to 550 ° C of 60 to 70 × 10 ^-7 / ° C.
6. A sealing material containing glass powder, fired and used for sealing,
   The glass powder is in terms of oxides: SiO ₂ : 14 to 21% by mass, Al ₂ O ₃ : 0 to 12% by mass, B ₂ O ₃ : 17 to 24% by mass, ZnO: 29 to 51% by mass, MgO : A sealing material, which is contained so as to have a composition ratio of 7 to 16% by mass.
7. The sealing material according to claim 6, comprising ceramic powder together with the glass powder, wherein a ratio of the ceramic powder in a total amount of the glass powder and the ceramic powder is more than 0% by mass and 5% by mass or less.

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