JP5449120B2 - Method for forming seal component and method for manufacturing solid oxide fuel cell module - Google Patents

Description

  The present invention relates to a method for forming a sealing component applied to a cylindrical horizontal stripe type solid electrolyte fuel cell or a cylindrical horizontal stripe type high temperature steam electrolysis cell, and a method for manufacturing a solid oxide fuel cell module.

  A solid oxide fuel cell (SOFC) is a battery that generates power by supplying a fuel gas to a fuel electrode and a fluid (air) containing oxygen to an air electrode.

  FIG. 1 illustrates a schematic diagram of a cylindrical horizontal striped SOFC cell tube. A cylindrical horizontal stripe SOFC cell tube has a porous base tube, and includes a unit cell membrane in which a fuel electrode, a solid electrolyte, and an air electrode are sequentially laminated on the outer peripheral surface of the base tube. A plurality of unit cell membranes are formed along the longitudinal direction of the base tube, and adjacent unit cell membranes are electrically connected to each other via an interconnector.

  In FIG. 2, the schematic of a cell tube edge part is shown. A lead film is formed on the outer peripheral surface of one end in the longitudinal direction of the base tube so as to be connected to the final end of the connected unit cell film. A current collecting member is provided at the other end of the lead film so that the electric power generated by the unit cell film is collected. An airtight film for protecting the lead film from electrons and oxygen gas is formed on the upper surface of the lead film.

  In the cylindrical horizontal stripe type SOFC having the above-described configuration, power is generated by supplying fuel gas inside the base tube and air to an air electrode arranged outside the base tube. In FIG. 1, the cell tube is held in a state of being penetrated by the tube plate, and spaces for supplying fuel gas and air are isolated from each other. Seal members are arranged between the tube plate and the cell tube and at one end of the cell tube so that the supplied fuel gas and air are not mixed.

  The seal member is usually bonded to the airtight film on the cell tube via an inorganic adhesive. However, when the hermetic membrane and the sealing member are directly bonded with an inorganic adhesive, the self-weight of the cell tube may not be supported because the adhesive strength is low. Moreover, the sealing performance of the cell tube may be reduced by a force generated by thermal stress or the like at the time of raising or lowering the temperature.

In order to solve the above problem, in Patent Document 1, an adhesion improving film is provided on the surface of an airtight film made of Al ₂ O _3, and an inorganic adhesive is applied to the surface of the adhesion improving film so that the sealing member is closely attached. A sealed structure of a fuel cell cell tube is disclosed.

The material of the adhesion improvement film is calcium titanate (CaTiO ₃ ), CSZ (calcia stabilized zirconia), YSZ (yttria stabilized zirconia), or a mixture thereof, which has been synthesized in advance. The mixture is slurried and applied onto an airtight membrane and then sintered.

JP 2009-181854 (paragraphs [0030] and [0031])

  The adhesion-improving film is formed by the sintering method at the same time when sintering the air electrode, when co-sintering the fuel electrode and the solid electrolyte, or when co-sintering the air electrode, the fuel electrode and the solid electrolyte. Molded. In particular, the adhesion improving film is often sintered simultaneously with the air electrode sintering.

  Conventionally, the sintering temperature at the time of sintering the air electrode has been 1300 ° C. However, in recent years, from the viewpoint of improving the durability, lowering the sintering temperature of the air electrode has been studied. Sintering at a temperature of about ℃ is becoming mainstream.

  However, when the air electrode and the adhesion improving film are sintered at the same time under the condition where the sintering temperature is lowered, that is, at a temperature of about 1100 ° C., the sinterability of the adhesion improving film decreases, Adhesiveness cannot be obtained sufficiently.

  The present invention has been made in view of such circumstances, and even when the sintering temperature is lowered and the air electrode is sintered at the same time, an adhesive improvement film showing desired adhesion is obtained. It is an object of the present invention to provide a method for forming a seal component that can be formed and a method for manufacturing a solid oxide fuel cell module including such a seal component.

In order to solve the above problems, the present invention provides a base tube made of a porous material, and a plurality of unit cell membranes in which a fuel electrode, a solid electrolyte, and an air electrode are sequentially laminated on the outer peripheral surface of the base tube. The cell tube comprising: a conductive lead film electrically connected to an outermost end of the plurality of unit cell films; and a highly airtight film formed on a surface of the lead film. A method for forming a sealing component provided on a membrane, which is a powder of a compound containing an alkaline earth metal carbonate that decomposes and releases carbon dioxide when heated at a temperature lower than a predetermined sintering temperature. And titania powder are mixed at a predetermined ratio to prepare an unsynthetic mixed powder, the mixed powder is slurried and applied onto the airtight film, and then the predetermined sintering temperature formula ATiO ₃ by heat treatment in (A is an alkali A method of forming a seal component containing the perovskite type oxide, and titania represented by cation) of metalloid.

The decomposition product of the compound immediately after releasing carbon dioxide by heating becomes very reactive. Therefore, the synthesis reaction between the decomposition product and titania can be promoted by mixing the alkaline earth metal carbonate powder and the titania powder in an unsynthesized state and heat-treating them at a predetermined sintering temperature. . When the decomposition product and titania are synthesized, a perovskite oxide represented by the general formula ATiO ₃ is generated. Further, when the mixed powder is heat-treated at a predetermined sintering temperature, the constituent particles (titania and synthesized perovskite oxide) are sintered together with the above synthesis reaction to form a film-like seal constituent member. According to the above invention, the formed sealing component hardly undergoes shrinkage due to sintering. Further, according to the above invention, since the diffusion proceeds sufficiently when the decomposition product and titania are synthesized, the adhesion between the constituent particles is strengthened, and a sealing member having a sound film quality can be formed. .

In one embodiment of the invention, the solid electrolyte mainly contains YSZ, the compound is calcium carbonate, and the mixing molar ratio of the calcium carbonate powder and the titania powder is 10 mol of titania. You may prepare mixed powder so that it may become 3 mol or more and 8 mol or less.

  Since calcium carbonate does not show deliquescence, it is easy to handle when applied onto an airtight membrane. In addition, since calcium carbonate has a characteristic of easily releasing carbon dioxide when heated, the synthesis reaction with titania is easy to proceed. The decomposition start temperature of calcium carbonate is about 600 ° C. According to one aspect of the invention, an excess amount of titania is added to calcium carbonate. Thus, even when heat treatment is performed at a low temperature of about 1100 ° C., the constituent particles (titania and calcium titanate) are sintered while synthesizing calcium titanate without leaving unreacted calcium carbonate remaining. Can do.

  According to one aspect of the invention, by mixing the calcium carbonate powder and the titania powder at the mixing molar ratio, the linear expansion coefficient of the mixed powder can be close to the linear expansion coefficient of YSZ. it can. By forming the seal constituent member with such a material, it becomes suitable as a member of a solid oxide fuel cell.

In one embodiment of the present invention, the solid electrolyte mainly contains YSZ, the compound is strontium carbonate, and the mixing molar ratio of the strontium carbonate powder and the titania powder is strontium carbonate with respect to 10 mol of titania. You may prepare mixed powder by mixing so that it may become 4 mol or more and 8 mol or less.

  Since strontium carbonate does not show deliquescence, it is easy to handle when applied on an airtight membrane. Since strontium carbonate has the property of releasing carbon dioxide when heated, it is easy to proceed with the synthesis reaction with titania. The decomposition start temperature of strontium carbonate is about 900 ° C. According to one aspect of the invention, an excess amount of titania is added to strontium carbonate. As a result, even when heat treatment is performed at a low temperature of about 1100 ° C., the constituent particles (titania and strontium titanate) are sintered together while synthesizing strontium titanate without leaving unreacted strontium carbonate. be able to.

  According to one aspect of the invention, by mixing the strontium carbonate powder and the titania powder at the mixing molar ratio, the linear expansion coefficient of the mixed powder may be close to the linear expansion coefficient of YSZ. it can. By forming the seal constituent member with such a material, it becomes suitable as a member of a solid oxide fuel cell.

The present invention also provides a base tube made of a porous material, a plurality of unit cell membranes in which a fuel electrode, a solid electrolyte, and an air electrode are sequentially laminated on the outer peripheral surface of the base tube, and the plurality of unit cells. A solid oxide fuel cell module having a cell tube comprising a conductive lead film electrically connected to the outermost end of the film and a highly airtight film formed on the surface of the lead film. A powder of a compound containing an alkaline earth metal carbonate that is decomposed by being heated at a temperature lower than a predetermined sintering temperature to release carbon dioxide on the hermetic film of the cell tube; A titania powder is mixed at a predetermined ratio to prepare an unsynthetic mixed powder, the mixed powder is slurried and applied onto the hermetic film, and then heat-treated at the predetermined sintering temperature. formula ATiO ₃ (A by the alk To provide a method of manufacturing a solid oxide fuel cell modules forming a seal component containing the perovskite type oxide, and titania represented by cation) of earth metals.

The decomposition product of the compound immediately after releasing carbon dioxide by heating becomes very reactive. Therefore, the synthetic reaction between the decomposition product and titania can be promoted by mixing such compound powder and titania powder in an unsynthesized state and heat-treating them at a predetermined sintering temperature. When the decomposition product and titania are synthesized, a perovskite oxide represented by the general formula ATiO ₃ is generated. Further, when the mixed powder is heat-treated at a predetermined sintering temperature, the constituent particles (titania and synthesized perovskite oxide) are sintered together with the above synthesis reaction to form a film-like seal constituent member. According to the above invention, the formed sealing component hardly undergoes shrinkage due to sintering. Further, according to the above invention, since the diffusion proceeds sufficiently when the decomposition product and titania are synthesized, the adhesion between the constituent particles is strengthened, and a sealing member having a sound film quality can be formed. . Moreover, according to the said invention, since the sealing performance of a cell tube can be improved, the solid electrolyte fuel cell module which reduced the leak rate of fuel gas significantly can be manufactured.

In one embodiment of the invention, the solid electrolyte mainly contains YSZ, the compound is calcium carbonate, and the mixing molar ratio of the calcium carbonate powder and the titania powder is 10 mol of titania. You may prepare mixed powder so that it may become 3 mol or more and 8 mol or less.

In one embodiment of the present invention, the solid electrolyte mainly contains YSZ, the compound is strontium carbonate, and the mixing molar ratio of the strontium carbonate powder and the titania powder is strontium carbonate with respect to 10 mol of titania. You may prepare mixed powder by mixing so that it may become 4 mol or more and 8 mol or less.

  According to the present invention, a powder mixture in which a predetermined compound and titania are mixed is applied onto an airtight film in an unsynthesized state, and heat treatment is performed at a predetermined sintering temperature, so that there is almost no shrinkage due to sintering, In addition, it is possible to form an adhesive improvement film (seal constituent member) having a firm and healthy film quality and having good adhesion between constituent particles. By using calcium carbonate or strontium carbonate as the predetermined compound, even when the predetermined sintering temperature is about 1100 ° C., it is possible to form an adhesion improving film that is difficult to peel off.

  In addition, according to the present invention, a highly reliable solid oxide fuel cell module with reduced fuel leakage can be manufactured.

It is a figure explaining the schematic structure of the solid electrolyte fuel cell module manufactured with the manufacturing method concerning a 1st embodiment. It is the schematic of the cell tube of the cylindrical horizontal stripe type | mold SOFC in 1st Embodiment. It is the schematic of the lower end part of the cell tube in 1st Embodiment. It is explanatory drawing which shows the film | membrane structure of the seal part in 1st Embodiment. It is a figure which shows the powder X-ray-diffraction result of a sintered compact. It is a photograph which shows the result of a scratch test.

  Hereinafter, an embodiment of a method for forming a sealing component according to the present invention and a method for producing a solid oxide fuel cell module will be described with reference to the drawings.

[First Embodiment]
FIG. 1 shows a schematic structure of a solid electrolyte fuel cell module 1 manufactured by the manufacturing method according to the present embodiment.
The solid electrolyte fuel cell module 1 includes a top plate 2, an upper tube plate 3, a lower tube plate 4, and a plurality of cell tubes 5. The solid electrolyte fuel cell module 1 is surrounded by a heat insulating material.

  A top plate 2, an upper tube plate 3, and a lower tube plate 4 are disposed in a solid electrolyte fuel cell module (module body) 1. A battery chamber 6 is formed below the lower tube sheet 4. A fuel supply chamber 7 is formed between the top plate 2 and the upper tube plate 3. A fuel discharge chamber 8 is formed between the upper tube plate 3 and the lower tube plate 4.

  An outer tube 9 that connects the fuel supply chamber 7 and the outside of the module body 1 passes through and is connected to the top plate 2 and the module body 1. Inside the outer tube 9, an inner tube 10 that penetrates the upper tube plate 3 is disposed so as to communicate the fuel discharge chamber 8 and the outside of the module body 1.

A plurality of cell tubes 5 are supported through the lower tube plate 4 such that the upper ends thereof are positioned in the fuel discharge chamber 8 and the lower portions thereof are positioned in the battery chamber 6 of the module body 1.
Inside the cell tube 5, a fuel supply pipe 11 penetrating the upper tube plate 3 is disposed so as to communicate the inside lower side of the cell tube 5 with the fuel supply chamber 7.

  Inside the fuel supply pipe 11, a current collecting rod 12 having an upper end positioned in the fuel supply chamber 7 and a lower end positioned in the vicinity of the lower end of the cell tube 5 is disposed. The lower end of the current collecting rod 12 is connected to the current collecting member 13 that is electrically connected to the unit cell membrane and closes the lower end of the cell tube 5. The upper end of the current collecting rod 12 is electrically connected to the outside of the module body 1 via a nickel current collecting member 13 and a conductive rod 14.

  A current collecting connector 15 that is electrically connected to the cell membrane is attached to the upper end of the cell tube 5. The current collecting connector 15 is electrically connected in series with another cell tube 5 via the current collecting connector 15.

A porous ceramic partition plate 16 is provided below the battery chamber 6 of the module body 1. An air preheating chamber 17 that communicates with the battery chamber 6 through the partition plate 16 is provided below the partition plate 16. An air supply pipe 18 that communicates with the outside of the module body 1 is connected to the air preheating chamber 17.
One end side of an air discharge pipe 19 is disposed inside the battery chamber 6 of the module body 1. The other end side of the air discharge pipe 19 is located outside the module main body 1, and the middle part is disposed so as to pass through the inside of the air preheating chamber 17 to exchange heat.

FIG. 2 illustrates a schematic diagram of a cylindrical horizontal striped SOFC cell tube 5.
On the outer peripheral surface of the cell tube 5, a plurality of single cell membranes 20 are formed along the longitudinal direction. A seal portion is provided at a side portion where the cell tube 5 is suspended and a lower end portion of the cell tube 5.
The outer peripheral surface of the portion of the cell tube 5 where the single cell membrane 20 is provided is a gas atmosphere containing oxygen. In this embodiment, the gas containing oxygen means air. When the solid oxide fuel cell module 1 is operated, fuel gas (hydrogen) is supplied to the inner peripheral side of the cell tube 5.

In FIG. 3, the schematic of the lower end part of the cell tube 5 is illustrated.
The cell tube 5 has a configuration in which a plurality of unit cell membranes 20 are formed on a base tube 21 made of a porous material. The unit cell membrane 20 has a structure in which a fuel electrode 22, a solid electrolyte 23, and an air electrode 24 are laminated in order from the base tube 21 side. Adjacent cell membranes are electrically connected in series by an interconnector 25. A lead film 26 is connected to the air electrode 24 at the final end of the connected unit cell film 20 via an interconnector 25. A highly airtight film 27 for protecting the lead film 26 is provided on the upper surface of the lead film 26, in other words, on the surface opposite to the base tube side of the lead film 26.

On the airtight film 27, a seal portion is provided. FIG. 4 shows the film configuration of the seal portion. The seal portion includes an adhesive improvement film 28 as a sealing component formed on the airtight film 27, a cap-shaped seal member 30 bonded to the adhesive improvement film 28 via an inorganic adhesive 29, It consists of
In addition, the side part which suspends the cell tube 5 also has the seal part of the same structure.

In the present embodiment, the base tube 21 is made of a porous material, such as calcia stabilized zirconia (CSZ).
The fuel electrode 22 is composed of a composite material of nickel (Ni) and a zirconia-based electrolyte material. For example, Ni / yttria stabilized zirconia (YSZ) is used.

  The solid electrolyte 23 is electronically insulating and is required to have gas tightness that does not allow gas to pass and high ion permeability at high temperatures. Therefore, YSZ is mainly used for the solid electrolyte 23.

The air electrode 24 is made of a lanthanum strontium-based material and generates oxygen ions from the air.
The interconnector 25 is composed of a conductive perovskite oxide represented by M _1-x L _x TiO ₃ (M is an alkaline earth metal element, L is a lanthanoid element) such as strontium titanate, and the like. It is a dense film so that it does not mix with air.

The lead film 26 is made of a composite material of Ni such as Ni / YSZ and a zirconia-based electrolyte material, or Ni / Al. The lead film 26 is a film that plays a role of collecting power generated by the connected unit cell films.
For the airtight film 27, alumina (Al ₂ O ₃ ), YSZ, or the like can be used.

The seal component (adhesion improving film) 28 is made of a perovskite oxide represented by the general formula ATiO ₃ and titania (TiO ₂ ). As a material of the seal component, a powder of a compound containing an alkaline earth metal carbonate that is decomposed by being heated at a temperature lower than a predetermined sintering temperature to release carbon dioxide, a titania powder, , Can be used at a predetermined ratio.
“A” in the general formula ATiO ₃ is preferably a cation such as an alkaline earth metal and does not exhibit toxicity. A compound containing an alkaline earth metal carbonate that is decomposed by being heated at a temperature lower than a predetermined sintering temperature to release carbon dioxide preferably does not exhibit deliquescence. Specifically, calcium carbonate (CaCO ₃ ), strontium carbonate (SrCO ₃ ) and the like are preferable.

  It mix | blends so that the titania amount (mol) in mixed powder may become excess with respect to the amount (mol) of the said compound. By "excess" is meant an amount that exceeds at least the amount that would theoretically allow all of the above compounds to react with titania.

The predetermined ratio may be appropriately set so that the linear expansion coefficient of the mixed powder is close to the linear expansion coefficient of the solid electrolyte (YSZ in the present embodiment).
For example, when calcium carbonate is used as the compound, the calcium carbonate may be mixed at a ratio of 3 mol or more and 8 mol or less with respect to 10 mol of titania.
For example, when strontium carbonate is used as the compound, it is preferable that strontium carbonate be mixed at a ratio of 4 mol to 8 mol with respect to 10 mol of titania.

As the inorganic adhesive 29, a one-component heat-curable inorganic adhesive such as Aron Ceramic available from Toagosei Co., Ltd. is used.
The seal member 30 is made of a metal such as Hastelloy X or SUS310.

Hereinafter, a method for producing a solid oxide fuel cell module will be described.
First, a porous material mainly made of calcia-stabilized zirconia (CSZ) or the like is formed into a tubular shape by an extrusion molding method, and dried to obtain a base tube 21.

Next, as a material of the fuel electrode 22, for example, a solvent is added to a mixed powder obtained by mixing NiO and YSZ at a predetermined mixing ratio, and the mixture is made into a slurry by using three rollers. Further, as the materials of the solid electrolyte 23, the interconnector 25, the lead film 26, and the airtight film 27, each material is similarly slurried.
After each slurry is sequentially formed on the base tube 21 by the screen printing method, heat treatment is performed under predetermined sintering conditions using an electric furnace or the like.

  Next, the material of the air electrode 24 is slurried in the same manner as the material of the fuel electrode 22 and the like. Further, the material of the adhesion improving film 28, for example, calcium carbonate powder and titania powder are mixed at a predetermined ratio, and mixed powder is obtained using a ball mill. An appropriate amount of a solvent is added to the obtained mixed powder to make a slurry. At this time, the material of the adhesion improving film 28 is characterized in that two kinds of powders are mixed in an unsynthesized state.

The slurry for the air electrode 24 is applied so as to cover the solid electrolyte 23 and the interconnector 25. The application is performed by a scoon printing method.
Further, a slurry for the adhesion improving film 28 is applied on the airtight film 27. The application is performed by a scoon printing method, and may be performed several times according to a desired film thickness.

  After drying each slurry for the air electrode 24 and the adhesion improving film 28 applied as described above, the base tube 21 is heat-treated at a predetermined sintering temperature by an electric furnace. The “predetermined sintering temperature” is appropriately set according to the material of the air electrode 24 and the like.

The operation of the cylindrical solid electrolyte fuel cell module manufactured by the manufacturing method according to the present embodiment will be described. The inside of the battery chamber 6 of the module main body 1 is heated to an operating temperature (about 900 to 1000 ° C.), a fuel gas 31 such as hydrogen is supplied from the outer tube 9, and air 32 as an oxidant gas is supplied from the air supply tube 18. Supply.
The fuel gas 31 supplied via the outer pipe 9 flows from the fuel supply chamber 7 to the lower end side of the cell tube 5 via the fuel supply pipe 11.
The air 32 that has passed through the partition 16 via the air preheating chamber 17 flows into the battery chamber 6.

  The fuel gas 31 passes through the porous base tube 21 and is supplied to the fuel electrode 22 of the unit cell membrane 20. When the air (oxygen) 32 comes into contact with the air electrode 24, the unit cell membrane 20 electrochemically reacts hydrogen and air (oxygen) to generate electric power, and the electric power is generated by the current collecting member 13 and the conductive rod 14. It is sent out to the outside through.

  The remaining fuel gas 33 after being used for power generation flows into the fuel discharge chamber 8 from the upper end of the cell tube 5, is discharged to the outside through the inner pipe 10, and is reused. On the other hand, the remaining air 34 after being used for power generation is discharged to the outside through the air discharge pipe 19.

(Pellet test)
An average particle size of 3 μm was used as the CaCO ₃ powder.
An average particle diameter of 2 μm was used as the TiO ₂ powder.
CaCO ₃ powder and TiO ₂ powder are mixed at a predetermined ratio (test composition: CaCO ₃ / TiO ₂ = 0/10 to 9/10), and the mixed powder is uniaxial using a φ20 mm mold. It was formed into pellets by press molding (press pressure: 300 kg / mm ² ) and sintered at 1100 ° C. for 2 hours. Next, the shrinkage ratio of the obtained sintered body was calculated. The shrinkage rate was calculated by comparing the size of the pellets before and after sintering. As the size of the pellet, a value obtained by measuring the diameter of the pellet with calipers at three locations every about 60 degrees and calculating an average value was adopted.

Table 1 shows the measured shrinkage rate.

According to Table 1, the shrinkage ratio of the sample without addition of CaCO ₃ (0 mol) was 13.3%. On the other hand, the shrinkage rate of the sample in which CaCO ₃ was added to TiO ₂ was 5% or less. In addition, the shrinkage ratio decreased with an increase in the amount of CaCO ₃ added, and almost no shrinkage occurred.

From the above results, it was confirmed that shrinkage after sintering can be suppressed when a mixed powder obtained by mixing CaCO ₃ powder and TiO ₂ powder in a predetermined ratio is sintered. This is because two kinds of powders are applied on an airtight film in an unsynthesized state, synthesized and sintered, so that a perovskite oxide having a larger particle size than that synthesized in advance is generated, It is thought that the shrinkage rate was lowered because sintering became difficult to proceed.
As a result, shrinkage cracks are less likely to occur during drying after film formation and during heat treatment, so that the limitation on the film thickness of the adhesion improving film is relaxed.

(X-ray diffraction)
The CaCO ₃ powder and TiO ₂ powder used in the pellet test were mixed with a ball mill and then dried to obtain a mixed powder. The mixing amounts of the CaCO ₃ powder and the TiO ₂ powder were 0.5 mol and 1 mol, respectively. Squeegee oil was added at a ratio of 18 g to 25 g of the mixed powder to make a slurry. The prepared slurry was applied onto a substrate and dried, followed by sintering at 1100 ° C. for 2 hours. The thickness after sintering was about 100 μm.

When sintering is performed in a state where CaCO ₃ powder and TiO ₂ powder are mixed, reactions of formulas (1) and (2) occur. The constituent crystal phases of the obtained sintered body are predicted to be CaTiO ₃ and TiO ₂ .
CaCO ₃ → CaO + CO ₂ ↑ (1)
CaO + TiO ₂ → CaTiO ₃ (2)

The obtained sintered body was analyzed by a powder X-ray diffractometer. The analysis results are shown in FIG. In the figure, the horizontal axis represents 2θ [°] and the vertical axis represents intensity [cps]. 5, peak ○ is derived from CaTiO _3, △ is a peak derived from TiO _2, construction crystal phase of the obtained sintered body, it was confirmed that the CaTiO ₃ and TiO _2.
When unreacted CaO remains in the sintered body, the strongest line of CaO appears at a position of 43.7 ° on the horizontal axis. According to FIG. 5, the presence of unreacted CaO was not found in the sintered body obtained above.

  Since CaO is easily hydrated, if CaO remains in the sintered body, it may cause damage to the adhesion improving film. Therefore, when CaO remains in the sintered body, it is necessary to verify the presence or absence of CaO by X-ray diffraction. According to the above result, since unreacted CaO does not remain in the sintered body, the step of verifying the presence or absence of CaO by X-ray diffraction after forming the adhesion improving film can be omitted.

(Linear expansion coefficient of sintered body)
The linear expansion coefficient of the sintered body is equal to that of the mixture of CaTiO ₃ and TiO ₂ . CaTiO _{3 has} a linear expansion coefficient of about 12 × 10 ⁻⁶ / K, and TiO _{2 has} a linear expansion coefficient of about 8 × 10 ⁻⁶ / K (see: Yoichi Motoki, Sintered Ceramics Details 4 Fine Ceramics Publication) (Gihodo 551p, 553p). Accordingly, from the existing ratio and CaTiO ₃ and linear expansion coefficient of TiO ₂ of CaTiO ₃ and TiO _2, it was calculated linear expansion coefficient of the mixture. The results are shown in Table 2.

According to Table 2, the estimated linear expansion coefficient of the sintered body is increased by adding CaCO ₃ to TiO ₂ . This is because the amount of CaTiO ₃ produced varies depending on the amount of CaCO ₃ added. That is, if the amount of CaCO ₃ added is small, the amount of CaTiO ₃ produced is small and the linear expansion coefficient is low. Conversely, when the amount of CaCO ₃ added is large, the amount of CaTiO ₃ produced increases and the linear expansion coefficient increases.

As the material used for the cell membrane, a material having a linear expansion coefficient close to that of the solid electrolyte to be used is usually selected so as not to cause peeling or cracking at the time of temperature increase / decrease. The linear expansion coefficient of YSZ mainly used as a solid electrolyte is 9.7 × 10 ⁻⁶ / K. Therefore, when YSZ is used as the solid electrolyte, even if the linear expansion coefficient is lower or higher than 9.7 × 10 ⁻⁶ / K, it causes peeling and cracking. From the above, the mixing ratio of CaCO ₃ and TiO ₂ is preferably ₃ mol or more and 8 mol or less, and more preferably 3 mol or more and 6 mol or less with respect to 10 mol of TiO ₂ .

Further, the linear expansion coefficient when SrCO ₃ and TiO ₂ were mixed at a predetermined ratio was calculated. The linear expansion coefficient of SrTiO ₃ is about 11.3 × 10 ⁻⁶ / K (see: Yoichi Motoki, Detailed explanation of sintered ceramics 4 Fine ceramics publisher, Gihodo 553p). The results are shown in Table 3.

From Table 3, the mixing ratio of SrCO ₃ and TiO ₂ is preferably ₃ mol or more and 8 mol or less, more preferably 4 mol or more and 6 mol or less with respect to 10 mol of TiO ₂ .

(Deposition test on airtight film)
The CaCO ₃ powder and TiO ₂ powder used in the pellet test were mixed with a ball mill and then dried to obtain a mixed powder. The mixing ratio of CaCO ₃ powder and TiO ₂ powder was 0.5 mol and 1 mol, respectively. An appropriate amount of squeegee oil was added to the mixed powder to form a slurry. The prepared slurry was applied onto an airtight film (10 mol% Y ₂ O ₃ —ZrO ₂ , thickness of about 100 μm, film formation method: dipping film formation), dried and then sintered at 1100 ° C. for 2 hours to improve adhesion. A film (thickness of about 50 μm) was formed and used as a sample.

The hermetic film after sintering was in a healthy state with no external cracking or peeling.
A grid test was performed on the sample. Specifically, the adhesion-improving film coated and sintered on the air-tight film is cut into a regular grid (grid pattern) so as to reach the substrate with a sharp blade, and is applied to the surface of the adhesion-improving film. Press the adhesive tape strongly with a roller. Thereafter, the end of the tape was quickly peeled off vertically, and the adhesion of the adhesion improving film was visually evaluated.
FIG. 6 is photographs before and after cutting the surface of the sample. FIG. 6A shows the surface of the adhesion improving film before notching and FIG. 6B after notching. According to FIG. 6, the film hardly peeled off after the notch.
On the other hand, an adhesive improvement film formed by slurrying a mixture of powder synthesized in advance and applying the mixture on an airtight film after sintering for 2 hours at 1100 ° C. is weak in adhesion and only hardens the powder. It was in such a state that the film was broken only by touching with a finger.

  As described above, according to the method for forming a seal constituent member according to the present invention, it is possible to form a seal constituent member that hardly causes sintering shrinkage and that has high adhesion.

1 Solid oxide fuel cell module (module body)
2 Top plate 3 Upper tube plate 4 Lower tube plate 5 Cell tube 6 Battery chamber 7 Fuel supply chamber 8 Fuel discharge chamber 9 Outer tube 10 Inner tube 11 Fuel supply tube 12 Current collecting rod 13 Current collecting member 14 Conductive rod 15 Current collecting connector 16 Partition plate 17 Air preheating chamber 18 Air supply pipe 19 Air discharge pipe 20 Single cell membrane 21 Base tube 22 Fuel electrode 23 Solid electrolyte 24 Air electrode 25 Interconnector 26 Lead film 27 Airtight film 28 Adhesion improvement film (seal component)
29 Inorganic adhesive 30 Seal member 31 Fuel gas 32 Air 33 Residual fuel gas 34 Residual air

Claims (6)

A base tube made of a porous material, a plurality of unit cell membranes in which a fuel electrode, a solid electrolyte, and an air electrode are sequentially laminated on the outer peripheral surface of the base unit tube; and at the end of the plurality of unit cell membranes A method of forming a sealing component member provided on the airtight film of a cell tube, comprising: an electrically connected conductive lead film; and a highly airtight film formed on the surface of the lead film. There,
A powder of a compound containing an alkaline earth metal carbonate that is decomposed by being heated at a temperature lower than a predetermined sintering temperature to release carbon dioxide and a titania powder are mixed at a predetermined ratio. An unsynthetic mixed powder is prepared, and the mixed powder is slurried and applied onto the airtight film, and then heat-treated at the predetermined sintering temperature to obtain a general formula ATiO ₃ (A is alkaline earth). A method of forming a seal constituent member comprising a perovskite oxide represented by a cation of a metal) and titania. The solid electrolyte mainly comprises YSZ;
The alkaline earth metal carbonate is calcium carbonate,
2. The seal configuration according to claim 1, wherein the mixed powder is prepared so that a mixing molar ratio of the calcium carbonate powder and the titania powder is 3 mol or more and 8 mol or less of calcium carbonate with respect to 10 mol of titania. A method of forming a member. The solid electrolyte mainly comprises YSZ;
The alkaline earth metal carbonate is strontium carbonate,
2. The seal structure according to claim 1, wherein the mixed powder is prepared such that the mixing molar ratio of the strontium carbonate powder and the titania powder is 4 mol or more and 8 mol or less of strontium carbonate with respect to 10 mol of titania. A method of forming a member. A base tube made of a porous material, a plurality of unit cell membranes in which a fuel electrode, a solid electrolyte, and an air electrode are sequentially laminated on the outer peripheral surface of the base unit tube; and at the end of the plurality of unit cell membranes A solid oxide fuel cell module having a cell tube comprising a conductive lead film electrically connected and a highly airtight film formed on the surface of the lead film,
On the airtight membrane of the cell tube,
A powder of a compound containing an alkaline earth metal carbonate that is decomposed by being heated at a temperature lower than a predetermined sintering temperature to release carbon dioxide and a titania powder are mixed at a predetermined ratio. An unsynthetic mixed powder is prepared, and the mixed powder is slurried and applied onto the airtight film, and then heat-treated at the predetermined sintering temperature to obtain a general formula ATiO ₃ (A is alkaline earth). A manufacturing method of a solid oxide fuel cell module that forms a seal constituent member made of a perovskite oxide represented by a cation of a metal) and titania. The solid electrolyte mainly comprises YSZ;
The alkaline earth metal carbonate is calcium carbonate,
5. The solid electrolyte according to claim 4, wherein the mixed powder is prepared such that the mixing molar ratio of the calcium carbonate powder and the titania powder is 3 mol or more and 8 mol or less of calcium carbonate with respect to 10 mol of titania. Type fuel cell module manufacturing method. The solid electrolyte mainly comprises YSZ;
The alkaline earth metal carbonate is strontium carbonate,
The mixed powder is prepared by mixing so that a mixing molar ratio of the strontium carbonate powder and the titania powder is 4 mol or more and 8 mol or less of strontium carbonate with respect to 10 mol of titania. Of manufacturing a solid oxide fuel cell module.

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