JP2003238201A - Sealing material, joined body, electrochemical apparatus, and crystallized glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide such a sealing material that can maintain sealing performance under such conditions under which the sealing material is exposed to oxidizing and reducing substances in a high temperature region or is exposed to heating cycles between a low temperature and a high temperature. <P>SOLUTION: The sealing material 8 consisting of crystallized glass is provided. While molten glass is brought into contact with object members 6 and 7 to be sealed, the temperature of the molten glass is lowered in this state. The molten glass is crystallized during the temperature lowering, by which the sealing material 8 is obtained. The coefficient of thermal expansion of the material constituting the object members 6 and 7 is 8×10<SP>-6</SP>to 12×10<SP>-6</SP>/K. More preferably, the crystallized glass is glass of Li<SB>2</SB>O-Al<SB>2</SB>O<SB>3</SB>-SiO<SB>2</SB>system and the main crystalline phase of the crystallized glass is lithium disilicate (Li<SB>2</SB>O.2 SiO<SB>2</SB>) phase. The object members preferably include electrochemical cells. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a sealing material, a bonded body and an electrochemical device. Further, the present invention relates to crystallized glass having a thermal expansion coefficient of 8 × 10 ⁻⁶ / K or more and 12 × 10 ⁻⁶ / K or less.

[0002]

2. Description of the Related Art As solid oxide fuel cells (SOFC), so-called flat plate type and cylindrical type have been proposed. Among them, the cylindrical SOFC is in the state of being most practically used, but there is a problem that the output density per unit area is low. Further, the flat plate type SOFC has a problem that sealing is difficult, although a relatively high power density can be obtained.

As a sealing material for SOFC, a molten glass made of borosilicate glass or Pyrex (registered trademark) glass has been known. Battery operating temperature, eg 1000
At ° C, Pyrex glass becomes a high-viscosity melt and functions as a sealant in this state. However, according to the description of Japanese Patent Application Laid-Open No. 10-92450, the melted seal material has a large difference in thermal expansion from other SOFC constituent materials, and therefore the distortion of the seal portion occurs as the battery temperature rises and falls. Cause the damage of the solid electrolyte and the deterioration of the sealing performance (see 0003). For this reason,
The invention described in Japanese Patent No. 92450 proposes a sealing method that does not use molten glass. That is, the raw glass before crystallization is brought into contact with the SOFC, and the temperature is raised in this state to soften the raw glass. And further SOF
By raising the temperature above the operating temperature of C (for example, 1000 ° C.) or higher, the once-softened raw glass is crystallized. Crystallized glass is a hard solid-state object and does not become molten at the operating temperature of SOFC. Japanese Unexamined Patent Application Publication No. 10-321244 also describes a similar sealing material made of crystallized glass.

[0004]

However, as a result of examination by the present inventor, it was found that such a sealing material has the following problems. That is, in the SOFC, if there is even a slight gas leak between the oxidizing gas and the reducing gas, the power generation output is significantly reduced, so it is important to maintain high leak prevention performance. However, when a sealing material made of crystallized glass was used, the adhesiveness at the interface between the crystallized glass and the ceramics constituting the SOFC was low, and as a result, some gas leakage was observed immediately after joining. Moreover, it was found that after the SOFC was subjected to a thermal cycle, the adhesiveness at the interface was further reduced and the gas leak amount tended to gradually increase.

It is an object of the present invention to maintain sealing performance under conditions such that it is exposed to oxidizing and reducing substances in a high temperature region and is exposed to a heating cycle between low temperature and high temperature. Another object is to provide a simple sealing material.

[0006]

DISCLOSURE OF THE INVENTION The present invention is an encapsulating material made of crystallized glass, which is used for lowering the temperature of molten glass while the molten glass is in contact with the target member to be sealed. The present invention relates to a sealing material, which is obtained by crystallizing molten glass.

The present invention also relates to a joined body, comprising the above-mentioned sealing material and a plurality of target members sealed by the sealing material.

Further, the present invention comprises an electrochemical cell having a hermetic solid electrolyte, an anode and a cathode, and another member whose airtightness should be maintained between the electrochemical cell. An electrochemical device comprising a sealing material for sealing an electrochemical cell and another member, the sealing material being obtained by crystallizing molten glass when the temperature of the molten glass is lowered. It is characterized by being made of crystallized glass.

The present inventor has conceived to obtain a sealing material by crystallizing the molten glass when the temperature of the molten glass is lowered while the molten glass is in contact with the target member. That is, once the molten glass is brought into contact with the target member, the adhesion between the glass and the target member is made extremely high, and then the temperature of the molten glass is lowered in this state,
Crystallization of the molten glass is performed in this temperature decreasing process. As a result, the adhesiveness at the interface between the encapsulant made of crystallized glass and the target member is high, and the high strength of crystallized glass can be utilized, so that it is strong against thermal cycles.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, molten glass is brought into contact with a target member. Then, when the temperature of the molten glass is lowered in this state, the molten glass is crystallized. Here, the heating temperature at the time of melting is not particularly limited, but is generally 800 to 1200 ° C. in many cases.

In the present invention, first, the temperature of the original glass (glass before crystallization) is raised and melted. here,
The raw glass first softens at the softening temperature specific to the raw glass. When the temperature is further raised, melting starts at the melting temperature specific to the raw glass. Next, the temperature of the molten glass is lowered, and the molten glass is crystallized while being maintained at a predetermined crystallization temperature. The softening temperature specific to the crystallized glass after crystallization is higher than the crystallization temperature and higher than the softening temperature of the original glass before crystallization.

Here, in the present invention, the heating temperature for melting the raw glass is preferably equal to or higher than the softening temperature of the crystallized glass. The heating temperature for melting the raw glass is more preferably the softening temperature of the crystallized glass + 20 ° C. or higher.

In a preferred embodiment, the maximum temperature during crystallization is set to be equal to or lower than the softening temperature of the crystallized glass, whereby the sealing performance can be further improved. Particularly preferably, the maximum temperature during crystallization is set to -50 ° C or lower of the softening temperature of the crystallized glass. When the present invention is applied to an electrochemical cell, the electrochemical cell is normally operated at a temperature not higher than the maximum temperature during crystallization.

The composition system of the crystallized glass is not particularly limited,
The following composition systems can be illustrated. _{Li 2 O-Al 2 O 3} -S
_{iO 2, Li 2 O-MgO} -Al 2 O 3 -SiO 2, M
_{gO-Al 2 O 3 -SiO 2} , Li 2 O-MgO-Al
_{2 O 3 -SiO 2, -P 2} O 5, Li 2 O-CaO-S
_{iO 2, Li 2 O-ZnO} -Al 2 O 3 -SiO 2, L
_{i 2 O-Al 2 O 3} -TiO 2 -SiO 2, Li 2 O-
_{Al 2 O 3 -SiO 2, -P} 2 O 5, Na 2 O-Al 2
O ₃ is _{-SiO 2, CaO-Al 2 O} 3 -SiO 2.

Preferably, the main crystal phase of the crystallized glass is a lithium disilicate (Li ₂ O.2SiO ₂ ) phase. In this case, the coefficient of thermal expansion of the crystallized glass of Li ₂ O—Al ₂ O ₃ —SiO ₂ system is 8 to 12 × 10 ⁻⁶ /.
It is easy to set it within the range of K. Here, the main crystal phase is a crystal phase having the largest volume among all crystal phases of crystallized glass.

In this case, as the sub-crystal phase, β-spodumene phase, cristobalite phase, quartz phase, eucryptite phase, petalite phase, Al ₂ O ₃ phase, Li ₂ O
-It may contain a SiO ₂ phase.

Preferably, the crystallized glass is at least β.
It preferably contains a Spodumene phase.

In the crystallized glass of the Li ₂ O—Al ₂ O ₃ —SiO ₂ system, the following composition systems are particularly preferable. SiO _2: 70 to 90 wt% (preferably 75 to 86 _wt%) Li 2 O: 5~20 wt% (preferably 10 to 17 _wt%) Al ₂ O 3: 2~15 wt% (preferably 2 to 8 _wt%) P ₂ O 5: 1~15 wt% (preferably 1 to 5% by weight)

In particular, 75 to 85% by weight of SiO ₂ , 14
A crystallized glass having a composition of ˜17 wt% Li ₂ O, 2-6 wt% Al ₂ O ₃ and 1-5 wt% P ₂ O ₅ can be prepared by adjusting the Li ₂ O ratio. 8x1
0 ^{-6 / K} or more, to adjust the coefficient of thermal expansion between 12 × 10 -6 ^{/ K,} was found to be adapted to the thermal expansion coefficient of the sealing target member. The relationship between the amount of Li ₂ O and the coefficient of thermal expansion of glass is illustrated in FIG. Specifically, when the materials of the two sealing target members are changed as shown in Table 1, if the thermal expansion coefficient of the sealing material is not within the "bondable thermal expansion range" of Table 1, the sealing is performed. Is difficult. The right column of Table 1 shows the amounts of Li ₂ O and Al ₂ O ₃ of the crystallized glass corresponding to the range of the coefficient of thermal expansion that can be joined.

[Table 1]

In the composition of the raw glass, SiO ₂ is an essential essential component for obtaining a crystal phase such as a lithium disilicate phase, but the amount of SiO ₂ is 70% by weight.
If it is less than 90%, it becomes difficult to deposit the lithium disilicate phase, and if it exceeds 90%, it becomes difficult to melt the raw glass.

When the Al ₂ O ₃ component in the raw glass exceeds 15% by weight, the amount of the eucryptite phase produced tends to be excessive, and the strength of the crystallized glass decreases.

[0022] Without the addition of ZrO ₂ in the glass-ceramics of the system, in the crystal eucryptite _{(Li 2 O · Al 2 O} 3 · 2SiO 2) phase and β- Supojuumen _(Li 2 · _Al 2 O _{The 3} · 4SiO ₂ ) phase is easily generated. However, it is also possible to add 10 wt% or less of ZrO ₂ .

Further, 2.0 parts by weight or less of Cr ₂ O ₃ ,
2.5 parts by weight or less of MnO can be contained in the crystallized glass.

Other components can be contained in the crystallized glass. First, TiO ₂ , SnO ₂ , Zr
O ₂ and noble metals such as gold, silver and platinum and fluorides such as CaF can be contained alone or in admixture of two or more. Further, 0 to 7% by weight of K ₂ O can be contained. This has the effects of lowering the melting and molding temperatures of the glass and suppressing devitrification of the glass during molding. In order to exert this effect, it is more preferable that the content is 2% by weight or more. Further, if the content exceeds 7% by weight, the strength of the crystallized glass tends to decrease.

Further, one or both of As ₂ O ₃ and Sb ₂ O ₃ may be contained in a total amount of 0 to 2% by weight. These are fining agents during glass melting. In addition, 0 to 3% by weight of B ₂ O ₃ component and 0 to 3 of CaO component
% By weight, SrO 0 to 3% by weight, BaO 0 to 3% by weight
Can be included.

When producing the raw glass, the respective raw materials containing the above-mentioned metal atoms are mixed so as to correspond to the above weight ratio, and the mixture is melted. As the raw material, oxides, carbonates, nitrates, phosphates of each metal atom,
A hydroxide can be illustrated. Next, the molten mixture is cooled to obtain a raw glass having a substantially uniform composition.

Then, preferably, the raw glass is crushed or crushed to obtain a powder of the raw glass. At least the powder of the raw glass is brought into contact with the sealing surface of the target member.

The method of bringing the powder of the raw glass into contact with the target member is not limited, but the following can be exemplified. (1) To each raw material containing each metal atom, a binder such as polyvinyl alcohol or methyl cellulose is added and mixed well to prepare a paste-like sealing mixture. This paste is applied to the sealing surface of the target member. (2) A binder such as polyvinyl alcohol or methyl cellulose is added to each raw material containing each metal atom and mixed well to obtain a fluid mixture. This fluid mixture is molded to obtain a molded product having a predetermined shape. This molded body is brought into contact with the sealing surface of the target member. The molded body is usually in the shape of a flat plate or a film, and the planar shape thereof conforms to the planar shape of the sealing surface. This molding method is not particularly limited, and examples thereof include a doctor blade method, a press molding method, and an extrusion molding method.

In this way, at least the powder of the raw glass is brought into contact with the sealing surface of the target member, and then heated and melted.

Here, when heating the raw glass, the temperature rising rate is 50 at least in the temperature range of 500 ° C. or higher.
The generation of crystal nuclei can be promoted by controlling the temperature to 300 ° C / hour. Also, at least 500 ° C
The generation of crystal nuclei can be promoted by holding in the temperature range of ˜580 ° C. for 1 to 4 hours.

The heating temperature for melting the Li ₂ O--Al ₂ O ₃ --SiO ₂ type raw glass is 800 to 1200 ° C.
It is preferable to set it as follows, and it is more preferable to set it as 900-1200 degreeC.

Next, the molten glass is cooled to crystallize it. At this time, it is preferable to promote crystallization by maintaining a predetermined temperature. _{Li 2 O-Al 2 O 3} -
In the case of SiO ₂ system, the crystallization temperature is 800 to 900.
C. is preferable, and 830 to 880.degree. C. is more preferable. The holding time in the above temperature range is particularly preferably 1 hour or more.

When the molten glass is cooled and crystallized, the crystal nuclei can be produced by temporarily lowering the temperature below the crystallization temperature. In this embodiment, it is preferable to maintain the temperature range of 450 to 580 ° C. At this time, it is also possible to raise and / or lower the temperature in the temperature range of 450 to 580 ° C. The temperature schedule according to this embodiment is shown in FIG. 6, for example.

In the present invention, the coefficient of thermal expansion of the target member to be sealed is not limited, but is preferably 8 × 10 ⁻⁶ / K or more and 12 × 10 ⁻⁶ / K or less. However, the coefficient of thermal expansion (α) was calculated by the following formula by measuring a value in the range of 40 to 800 ° C. with a differential expansion meter. l ₄₀ represents the sample length at 40 ° C. and l ₈₀₀ represents the sample length at 800 ° C.

[Equation 1]

The member to be sealed is a ceramic member,
It may be a metal member or a ceramic-metal composite material. Preferably, at least a ceramic member is included. The type of ceramics is not limited, but zirconia, lanthanum chromite, lanthanum manganite, magnesia-
It may be an alumina spinel. Further, as the composite material, a metal-zirconia cermet such as nickel-zirconia cermet can be exemplified. As a metal, 94C
refractory metal such as r5FeY ₂ O ₃ nickel and the like.

The electrochemical cell targeted by the present invention means a general cell for causing an electrochemical reaction.

When the encapsulating composition of the present invention is applied to an electrochemical cell, solid electrolyte, interconnector, anode, cathode, flange,
It is preferably applied to a gas supply member such as a manifold or a supply pipe.

For example, the electrochemical cell can be used as an oxygen pump or a high temperature steam electrolysis cell. The high temperature steam electrolysis cell can be used in a hydrogen production device and also in a steam removal device. In addition, the electrochemical cell is set to NOx, SO
It can be used as a decomposition cell of x. This decomposition cell can be used as a device for purifying exhaust gas from automobiles and power generators. Further, in a preferred embodiment, the electrochemical cell is a solid oxide fuel cell.

In the electrochemical cell, the oxidizing gas is not particularly limited as long as it can supply oxygen ions to the solid electrolyte membrane, and examples thereof include air, diluted air, oxygen and diluted oxygen.

As the reducing gas, H ₂ , CO, CH _{4 can be used.}
And these mixed gases can be illustrated.

The material that can be used as the interconnector is not particularly limited as long as it has electronic conductivity, but it is a perovskite type complex oxide containing lanthanum for the reason of heat resistance. More preferably, lanthanum chromite is preferable from the viewpoint of heat resistance, oxidation resistance, and reduction resistance.

The material that can be used as the solid electrolyte is not particularly limited as long as it has ionic conductivity, but yttria-stabilized zirconia or yttria partially-stabilized zirconia is used because of its high oxygen ion conductivity. Cerium oxide is preferred.

The anode is not particularly limited as long as it is a reducing catalyst, and is preferably a perovskite type complex oxide containing lanthanum because of its high oxygen reducing property, and further, lanthanum manganite or Lanthanum cobaltite is preferred. Palladium, platinum,
Ruthenium, platinum-zirconia mixed powder, palladium-zirconia mixed powder, ruthenium-zirconia mixed powder, platinum-cerium oxide mixed powder, ruthenium-cerium oxide mixed powder and the like can also be used.

Although lanthanum chromite and lanthanum manganites can be used alone, strontium, calcium, and
Chromium (for lanthanum manganese), cobalt,
It is also possible to dope with iron, nickel, aluminum and the like.

Materials that can be used as the cathode are
Although it is not particularly limited as long as it is an oxidation catalyst, nickel, palladium,
Platinum, nickel-zirconia mixed powder, platinum-zirconia mixed powder, palladium-zirconia mixed powder, nickel-cerium oxide mixed powder, platinum-cerium oxide mixed powder, palladium-cerium oxide mixed powder, ruthenium,
It is preferable to use ruthenium-zirconia mixed powder.

When an electrochemical cell and an external manifold are used and an oxidizing gas or a reducing gas is distributed from the manifold, the material of the manifold is magnesia-alumina spinel, zirconia, or alumina. preferable.

In a preferred embodiment, the electrochemical cell includes a honeycomb-shaped support, and at least a part of the support is made of a gas-tight solid electrolyte material. Then, a plurality of oxidizing gas channels and a plurality of reducing gas channels are provided, the oxidizing gas channel faces the anode, and the reducing gas channel faces the cathode. Particularly preferably, a honeycomb-shaped electrochemical cell is used for a manifold for supplying each gas to each oxidizing gas channel and each reducing gas channel, using the sealing material of the present invention. To join.

[0048]

EXAMPLES (Experiment A) (Production of Molded Article 4 of the Present Invention) Li ₂ O: 12.6% by weight, Al ₂ O ₃ : 5.0% by weight, SiO ₂ : 78.0% by weight, K Each oxide powder was prepared in a ratio of ₂ O: 2.4 wt% and P ₂ O ₅ : 2.0 wt%. After mixing the prepared powders, the prepared powders were put in a platinum crucible and melted at 1400 ° C. for 3 hours, and the obtained melt was put into water and cooled to prepare a glass gob. This glass gob was crushed in an alumina mortar to obtain a raw glass powder having an average particle size of 5 μm.

With respect to 98% by weight of the above raw glass powder,
2% by weight of polyvinyl alcohol (organic binder) was added to prepare a powder for press molding. The powder is press-molded by a die pressing method, and as shown in FIG.
A ring-shaped molded body 4 having an outer diameter of 10 mm, an inner diameter of 8 mm and a thickness of 0.5 mm was produced.

(Production of Member 6 to be Sealed) 2% by weight of polyvinyl alcohol was added to 98% by weight of 8 mol yttria-stabilized zirconia powder to prepare a powder for press molding. This powder was press-molded to prepare a pipe-shaped molded body having an outer diameter of 14 mm, an inner diameter of 12 mm and a length of 50 mm. The compact was fired in air at 1400 ° C. for 3 hours. The fired body obtained is processed to have an outer diameter of 10 mm and an inner diameter of 8 m.
A cylindrical member 6 having m and a length of 30 mm was obtained.

Further, 2% by weight of polyvinyl alcohol was added to 98% by weight of calcium dope lanthanum chromite powder to prepare a powder for press molding, and this powder was press molded to have an outer diameter of 14 mm, an inner diameter of 12 mm and a length of 50 m.
A pipe-shaped molded body of m was produced. This molded body was fired in air at 1500 ° C. for 3 hours, and the obtained fired body was processed to obtain a cylindrical member 6 having an outer diameter of 10 mm, an inner diameter of 8 mm and a length of 30 mm.

(Production of Target Member 7) 2% by weight of polyvinyl alcohol was added to 98% by weight of magnesia-alumina spinel powder to prepare a powder for press molding. This powder was press-molded to give an outer diameter of 14 mm, an inner diameter of 12 mm,
A pipe-shaped molded body having a length of 50 mm was produced. This formed body is fired in air at 1500 ° C. for 3 hours, and the obtained fired body is processed to have an outer diameter of 10 mm, an inner diameter of 8 mm, and a length of 30 mm.
The cylindrical member 7 of was obtained.

(Manufacture of bonded body A) The cylindrical member 6 made of 8 mol yttria-stabilized zirconia, the cylindrical member 7 made of magnesia-alumina spinel, and the molded body 4 are shown in FIG. 1 (a). It was set in the electric furnace. 960 ° C at a heating rate of 200 ° C / hour in the air
The temperature was raised up to and kept at 960 ° C. for 1 hour to melt the raw glass. Here, the heating temperature at the time of melting 960 ° C. was set higher than the softening temperature (920 ° C.) of the present crystallized glass. Then, the temperature was lowered to 860 ° C., and the temperature was kept at 860 ° C. for 3 hours to perform crystallization treatment. Next, the electric furnace was cooled to obtain a joined body 5 including a member 6 made of stabilized zirconia / a sealing material 8 / a member 7 made of magnesia-alumina spinel.
This joined body is referred to as a joined body A.

(Manufacture of Bonded Body B) In the bonded body A, the material of the member 6 was the above-described calcium dope tank chromite. Then, the member 6 was joined to the member 7 using the crystallized glass of the present invention as described above. The obtained joined body is referred to as a joined body B (member 6 made of lanthanum chromite / sealant 8 / member 7 made of magnesia-alumina spinel).

(Comparative Example 1) TiO ₂ : 9% by weight, Al ₂ O
Each powder was prepared with a composition of ₃ : 23% by weight, SiO ₂ : 48% by weight, and MnO ₂ : 19% by weight. The coefficient of thermal expansion of the crystallized glass of this composition is close to that of zirconia, and thus was used as a comparative sample. After mixing this powder, the prepared powder was put into a platinum crucible and melted at 1400 ° C. for 3 hours, and the melt was put into water and cooled to prepare a glass lump. This glass was crushed in an alumina mortar to obtain a powder having an average particle size of 5 μm. 2% by weight of polyvinyl alcohol and water were added to this powder and wet-mixed, and the obtained slurry was dried and crushed to obtain a raw glass powder for sealing. This powder was molded by a die pressing method, and had an outer diameter of 10 mm, an inner diameter of 8 mm and a thickness of 0.
A ring-shaped molded body 4 of 5 mm was produced.

The above-mentioned members 6 and 7 and the molded body 4 are shown in FIG.
It was set in an electric furnace as shown in (a). In an air atmosphere, the temperature is raised to 1050 ° C. at a heating rate of 200 ° C./hour,
It was kept at 1050 ° C. for 3 hours for crystallization treatment.
Then, the member is cooled and is made of stabilized zirconia 6 / sealant 8 / magnesia-alumina spinel member 7
(Joined body C) or member 6 made of lanthanum chromite / sealant 8 / member 7 made of magnesia-alumina spinel (joined body D) was manufactured.

(Comparative Example 2) Pyrex glass powder 98
2% by weight of polyvinyl alcohol was added to the weight% to prepare a powder for press molding. This powder was molded by a die pressing method to prepare a ring-shaped molded body 4 having an outer diameter of 10 mm, an inner diameter of 8 mm and a thickness of 0.5 mm. This molded body 4 and the above-mentioned members 6 and 7 were set in an electric furnace as shown in FIG. In an air atmosphere, the temperature was raised to 860 ° C. at a heating rate of 200 ° C./hour, and the temperature was maintained at 860 ° C. for 1 hour to melt the molded body 4. Then, it is cooled and then a member 6 made of stabilized zirconia / a sealing material 8 / a member 7 made of magnesia-alumina spinel (joined body E) or a member 6 made of lanthanum chromite / a sealing composition 8 / magnesia- Member 7 made of alumina spinel (joined body F)
Was manufactured.

(Leak Test) Each bonded body 5 was set as shown in FIG. Specifically, the lids 1 are provided on both ends of each bonded body 5.
2, 13 were fixed via O-rings. One lid 1
Nitrogen gas was introduced from the No. 3 side through the supply pipe 14 as shown by an arrow B, the pressure was observed by the gauge 15, the pressure was maintained at 1 atm by the gauge pressure, and the leak amount from the bonded body 5 was measured by the mass flow meter 16. did. Next, the bonded body was immersed in an alcohol solution, and the presence or absence of gas leak at the bonded portion was observed. The results of these measurements are shown in Table 2.

(Heat Cycle Test) A heat cycle test was performed in the atmosphere. Five sets of pipe-shaped joined bodies were set in an electric furnace. Temperature rising rate of 200 ℃ in air
The temperature is raised to 800 ° C./hour and kept at 800 ° C. for 1 hour.
After that, the temperature was decreased to 100 ° C. at a temperature decreasing rate of 200 ° C./hour, and the temperature was kept at 100 ° C. for 1 hour. This heating / cooling cycle was repeated 10 times to perform a thermal cycle test. Then, the leak test was performed. Further, the same heat cycle test was carried out in a hydrogen atmosphere. That is, the temperature was raised to 800 ° C. at a temperature rising rate of 200 ° C./hour in a hydrogen atmosphere, held at 800 ° C. for 1 hour, and then lowered to 200 ° C.
The temperature was decreased to 100 ° C. at a temperature of 100 ° C./hour, and the temperature was maintained at 100 ° C. for 1 hour. This heating / cooling cycle was repeated 10 times to perform a thermal cycle test. Then, the leak test was performed. The results of these measurements are shown in Table 2.

[0060]

[Table 2]

As in Comparative Example 1, when ordinary crystallized glass was used, the thermal expansion of the encapsulant and the target member was consistent during the firing schedule, but the target member The amount of gas leak is large due to poor adhesion at the interface. Further, due to insufficient adhesive strength, the amount of gas leak increased after the heat cycle. The glass seal (melt seal) of Comparative Example 2 is likely to be cracked due to mismatch of thermal expansion. Therefore, it can be used as a melt seal at high temperatures, but the seal performance cannot be maintained after cooling.

In the examples of the present invention, good results were obtained for both the bonded bodies A and B. That is, in the example of the present invention, since melting and sealing are performed at a temperature (960 ° C.) higher than the softening temperature (920 ° C.) of the crystallized glass, the adhesion between the sealing material and the target member at the interface is good. Moreover, the high strength characteristic of crystallized glass can be utilized. Therefore, by matching the thermal expansion coefficient of the sealing material with the thermal expansion coefficient of the target member (zirconia, lanthanum chromite, spinel),
It was found that the high sealing performance can be maintained even after the thermal cycle both in the reducing atmosphere and in the air.

(Experiment B) (Production of Honeycomb Cell) A honeycomb-type cell 21 having a cross section as shown in FIG. 4 was produced. 5 parts by weight of methyl cellulose and 18 parts by weight of water were added to 100 parts by weight of 8 mol yttria-stabilized zirconia powder and kneaded to prepare a kneaded material for extrusion molding. Similarly, a kneaded material of lanthanum chromite powder was prepared. Honeycomb dies (30 mm long × 9 mm wide, hole pitch 3 mm,
A wall thickness of 300 μm) was set, and a laminated honeycomb molded body having three layers of lanthanum chromite / zirconia / lanthanum chromite was formed. This molded body has a cross-sectional shape substantially shown in FIG. The formed body was dried at 100 ° C. and fired in air at 1500 ° C. for 3 hours to produce a honeycomb-shaped support body 29. The support 29 is composed of two lanthanum chromite layers 22A and 22B and a zirconia layer 23 between them. Each lantern chromite layer 22
Through holes 24 and 25 are formed by A and 22B and the intermediate zirconia layer 23. In this example, the lanthanum chromite layers 22A and 22B act as interconnectors or separators, and the zirconia layer 23 acts as a solid electrolyte part.

Next, platinum slurry is applied to the inner surfaces of the through holes 24 and 25 of the honeycomb-shaped support 29, and the platinum slurry is applied to
Platinum was baked at 00 ° C. to form the anode 26 and the cathode 27. Therefore, in this example, 19 acts as an oxidizing gas passage and 20 acts as a reducing gas passage.

(Preparation of Manifold) 2% by weight of polyvinyl alcohol was added to 98% by weight of magnesia-alumina spinel powder to prepare a powder for press molding.
This powder was press-molded to prepare a molded body having a length of 30 mm, a width of 15 mm and a thickness of 12 mm. In the air,
Manifold 1 shown in FIG. 3 after firing at 1500 ° C. for 3 hours
5A and 15B were produced.

(Cell 21 and manifold 15A, 15B
Bonding with the original glass powder 9 of the present invention described in Experiment A
2 parts by weight of methyl cellulose and alcohol were added to 8% by weight to form a paste. This paste
It was applied to both end faces of the honeycomb cell 21, and the manifolds 15A and 15B were adhered to each other. Then, gas supply pipes 13A, 13B, 14A, 14B made of magnesia-alumina spinel were inserted into the through holes of the manifold. The above-mentioned paste was also interposed between each gas supply pipe and the manifolds 15A and 15B.

The assembly was dried and set in an electric furnace. 96 at a heating rate of 200 ° C / hour in the air
Heat to 0 ° C and hold at 960 ° C for 1 hour to melt
Then, the temperature was lowered to 860 ° C, and the temperature was kept at 860 ° C for 3 hours.
Crystallization treatment was performed. Then, it cooled and the joined body of FIG. 3 was obtained. Here, the manifolds 15A and 15B and the cell 21 are joined by sealing materials 17A and 17B, respectively, and the manifolds 15A and 15B and the gas supply pipes 1 are connected to each other.
3A, 13B, 14A, and 14B are joined by the sealing material 18.

A leak test was conducted on the obtained bonded body under the same conditions as in Experiment A. However, one gas supply pipe 1
Nitrogen gas was flown through 3A, and the outlet of the other gas supply pipe 13B was sealed with a lid. As a result, the gas leak amount is 0.0
It was 2 cc / min or less. Also, no gas leak was observed when the bonded body was observed by immersing it in alcohol.
Next, nitrogen gas was caused to flow through the other gas supply pipe 14A, and the outlet of the one gas supply pipe 14B was sealed with a lid. Then, the leak test described above was performed. Gas leak amount is 0.0
It was 2 cc / min or less. Also, no gas leak was observed when the bonded body was observed by immersing it in alcohol.

(Power Generation Test) A platinum mesh 16 for current collection was set on the above-mentioned joined body which had been subjected to the leak test. Air is supplied to the gas supply pipe 13A, and the gas supply pipe 14
A hydrogen gas was supplied to A, and an argon gas was caused to flow around the bonded body to perform a power generation test. 80 at a heating rate of 200 ° C / min
The temperature was raised to 0 ° C., and the temperature was kept at 800 ° C. for 8 hours to generate power. Next, power generation was stopped and the temperature was lowered to 200 ° C. This operation is repeated 10 times, and the cell 21
Was taken out and the above-mentioned leak test was conducted. In all samples, the gas leak rate was 0.02 cc / min or less. Also, no gas leak was observed when the bonded body was observed by immersing it in alcohol. In this example, the power generation test was performed using one cell 21, but power generation was also possible when two or more cells 21 were stacked to form a stack.

(Experiment C) A glass was produced in the same procedure as in Experiment A. The melting temperature is 1300 ° C and the composition is Si
O ₂ : 75.5% by weight, P ₂ O ₅ : 2.0% by weight, K ₂ O:
2.5 wt%, Al ₂ O ₃ is 6.7 to 3.9 wt%, Li
₂ O is Al ₂ O ₃ and Li in the range of 13.3 to 16.1% by weight.
A glass was prepared by adding ₂ O so that the glass content became 20% by weight. The coefficient of thermal expansion of glass is 9 to 12 as shown in FIG.
× 10 ⁻⁶ (/ K). Then, in the same manner as in Experiment A, a ring-shaped molded body 4 was obtained.

In the same manner as in Experiment A, 8 mol yttria-stabilized zirconia (coefficient of thermal expansion: 10.5 × 10
^-6 / K), lanthanum chromite (9.9 × ^{10 -} 6 /
K), spinel (10.5 × 10 ⁻⁶ / K), and nickel zirconia cermet (12.5 × 10 ⁻⁶ / K). The firing condition of the nickel zirconia cermet was 1400 ° C. for 3 hours. Then, a bonded body was manufactured in the same manner as in Experiment A. However, the combination of members to be sealed is shown in Table 3, and the glass composition is shown in Table 4. The firing schedule is shown in FIG. The coefficient of thermal expansion of each material is an actual value measured by a differential thermal expansion meter.

[0072]

[Table 3]

[0073]

[Table 4]

In each of the examples shown in Table 3, a leak test was conducted in the same manner as in Experiment A. As a result, no leak was seen. Then, the heat cycle described in the above "heat cycle test" was carried out 30 times, and then a leak test was carried out. After this, those in which no leak was observed were represented by “◯” in Table 3, and those in which leakage was observed were represented by “Δ” in Table 3.

[0075]

As described above, according to the present invention, exposure to oxidizing and reducing substances in a high temperature range,
Further, it is possible to provide the encapsulating material capable of maintaining the encapsulating performance under the condition of being exposed to the heating cycle between the low temperature and the high temperature.

[Brief description of drawings]

1A is a front view showing an assembly of members 6 and 7 to be sealed and a molded body 4 of a raw glass powder for sealing, and FIG. 1B is a front view showing the molded body 4 heated. It is a front view which shows the joined body 5 obtained by making it fuse | melt.

FIG. 2 is a schematic diagram showing a leak test method for a bonded body 5.

FIG. 3 is a schematic diagram showing how the manifold and the gas supply pipe are attached to the cell 21.

FIG. 4 is a cross-sectional view showing a cell 21.

FIG. 5 is a graph showing the relationship between the amount of lithia and the amount of alumina of crystallized glass and the coefficient of thermal expansion.

FIG. 6 shows the temperature schedule for Experiment C.

[Explanation of symbols]

4 Molded body of raw glass powder for sealing 5 Bonded bodies 6 and 7 Target member for sealing 8 Sealing material 1
3A, 13B, 14A, 14B gas supply pipe 1
5A, 15B manifold 17A, 17B,
18 Sealing Material 19 Oxidizing Gas Flow Path 2
0 Reducing gas flow path 21 Solid oxide fuel cell 22A, 22B Separator 23 Solid electrolyte part 26 Anode 27
Cathode 29 honeycomb-shaped support

Continued front page    (72) Inventor Nobuaki Kawai             2-56, Sudacho, Mizuho-ku, Nagoya-shi, Aichi             Inside Hon insulator Co., Ltd. (72) Inventor Shinji Kawasaki             2-56, Sudacho, Mizuho-ku, Nagoya-shi, Aichi             Inside Hon insulator Co., Ltd. F-term (reference) 4G026 BB02 BB05 BB21 BF02 BF42                       BG02 BG30 BH13                 4G062 AA08 AA11 BB01 CC09 DA07                       DB01 DB02 DB03 DB04 DC01                       DD01 DD02 DD03 DD04 DE01                       DE02 DF01 EA03 EA04 EB01                       EC01 ED01 ED02 EE01 EE02                       EF01 EG01 FA01 FA10 FB01                       FC01 FD01 FE01 FF01 FG01                       FH01 FJ01 FK01 FL01 GA01                       GA10 GB01 GC01 GD01 GE01                       HH01 HH03 HH05 HH07 HH09                       HH11 HH13 HH15 HH17 HH20                       JJ01 JJ03 JJ05 JJ07 JJ10                       KK01 KK03 KK05 KK07 KK10                       MM17 MM23 MM40 NN34 QQ02                       QQ03 QQ06 QQ09 QQ11                 5H026 AA06 CV02 EE12 HH00 HH05

Claims (11)

[Claims] 1. An encapsulating material made of crystallized glass, which crystallizes the molten glass when the temperature of the molten glass is lowered while the molten glass is in contact with a target member to be sealed. Characterized by being obtained by
Sealing material. 2. The encapsulant according to claim 1, wherein the target member includes at least a ceramic member. 3. The thermal expansion coefficient of the material forming the target member is 8 × 10 ⁻⁶ / K or more and 12 × 10 ⁻⁶ / K or less, according to claim 1 or 2. Sealing material. 4. The method according to claim 1, wherein the material is exposed to an oxidizing gas and a reducing gas at a temperature of 600 ° C. or higher.
The sealing material according to any one of claims 1 to 3. 5. The crystallized glass is Li ₂ O—Al ₂ O ₃
The encapsulant according to any one of claims 1 to 4, which is a -SiO ₂ -based glass. 6. The encapsulant according to claim 5, wherein the main crystal phase of the crystallized glass is a lithium disilicate (Li ₂ O.2SiO ₂ ) phase. 7. A sealant according to any one of claims 1 to 6, and a plurality of target members sealed by the sealant. Zygote. 8. An electrochemical device comprising an electrochemical cell having an airtight solid electrolyte, an anode and a cathode, and another member whose airtightness is to be maintained between the electrochemical cell and the electrochemical cell. It is provided with a sealing material that seals the electrochemical cell and the other member, and the sealing material was obtained by crystallizing the molten glass when the temperature of the molten glass was lowered. An electrochemical device comprising a crystallized glass. 9. The crystallized glass is Li ₂ O—Al ₂ O ₃
9. The electrochemical device according to claim 8, wherein the electrochemical device is —SiO ₂ glass. 10. The electrochemical device according to claim 9, wherein the main crystal phase of the crystallized glass is a lithium disilicate (Li ₂ .2SiO ₂ ) phase. 11. 8 × 10 ⁻⁶ / K or more, 12 × 10 ⁻⁶
Has a coefficient of thermal expansion of less than / K, 75-85% by weight
Of SiO ₂ , 14-17 wt% Li ₂ O, 2-6 wt% Al ₂ O ₃ and 1-5 wt% P ₂ O ₅ :, a crystallized glass.