JP2012146579A - Material for anode support, and method for manufacturing anode support - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anode support material for a solid oxide fuel cell having a high purity and capable of obtaining a high strength even if burned at low temperatures, and a method for manufacturing an anode support for a solid oxide fuel cell having a high porosity, a high purity, and a high strength.SOLUTION: An anode support material 10 can obtain a high strength by burning at low temperatures of 1400°C or lower without adding another burning assistant because nickel oxide (II) powder 14 having a large specific surface area of 1 to 12 m/g and high activity adheres to the surface of fused zirconia powder 12 having a large average particle size of 10 to 50 μm and a high strength, and the nickel oxide (II) powder 14 has excellent sintering properties. Thus, the anode support material 10 is suitably used to form an electrolyte layer on an unburned formed body for constituting an anode support and then burn both at a time, and can obtain a high porosity and a high strength by low-temperature burning in spite of the high purity.

Description

  The present invention relates to a method for producing an anode support (also referred to as a current collecting layer) for use in an anode-supported solid oxide fuel cell (hereinafter referred to as SOFC) and a raw material for producing the same.

The porous support for SOFC is desired to have a large pore diameter and a high porosity so that a large amount of gas can permeate. Therefore, for example, while using a raw material having a relatively large particle size, an organic compound such as fibrous cellulose is added as a pore-forming agent and burned to form pores, thereby forming a porous structure. (See, for example, Patent Document 1). It has also been proposed to increase the mechanical strength while maintaining a high porosity by adding an appropriate amount of Al ₂ O ₃ as a sintering aid to control the sinterability (see, for example, Patent Document 2). .

  In addition, since the porous support is desired to have high mechanical strength for easy handling, the applicant of the present application uses coarse electrofused zirconia powder and improves its sinterability. Thus, a method for producing a porous body having high strength while maintaining a high porosity has been proposed (see, for example, Patent Documents 3 and 4). The method for producing a porous material described in Patent Document 3 granulates a raw material containing coarse electrofused zirconia powder, fine zirconia powder, and a zirconium-containing solution or a titanium-containing solution, and uses this raw material powder. Are subjected to molding and firing treatment. According to this technique, since a large gap is formed around the contact portion between the fused zirconia powders having large surface irregularities, fine zirconium crystals precipitated from fine zirconia powders or zirconium-containing solutions. As a result of the sintering of the fused zirconia powder being promoted at the contact portion, a porous body having a large number of communicating pores derived from the gaps between the fused zirconia powder is obtained.

  In addition, the method for producing a porous material described in Patent Document 4 described above is that a coarse electrofused zirconia powder is put into a granulation container, and the dispersion or zirconium containing fine zirconia powder is rotated while the container is rotated. By spraying a salt solution or the like into a container, a granulated powder is prepared in which the fused zirconia powder is bonded to each other with fine zirconia powder in between, and the granulated powder is used. Molding and firing are performed. In this technique, similarly to the technique described in Patent Document 3, the sintering of the electrofused zirconia powder is promoted at the mutual contact portion, and a porous body having a large number of communicating pores is obtained.

Japanese Patent Laid-Open No. 03-034259 JP 07-315922 A JP 2006-124256 A JP 2008-284501 A Japanese Patent Application Laid-Open No. 08-287921 JP 2009-196870 A

By the way, the porous support as described above is composed of a mixture obtained by adding nickel (II) oxide (= NiO) powder to stabilized zirconia, and this porous support is used as an anode, that is, on the anode support. An anode-supported SOFC in which a solid electrolyte layer and a cathode layer are provided is proposed (for example, see Patent Document 5). Nickel (II) oxide is a semiconductor material, but when used in SOFC, it is reduced to H ₂ by Ni, so that high conductivity is exhibited in the anode support. Therefore, since the anode support also functions as a current collecting layer, there is an advantage that the SOFC structure is simplified and the entire thickness can be reduced.

  On the other hand, as the cost of the porous support is reduced, the performance of the membrane material is increased, and the thickness of the film is reduced, the solid electrolyte thin film is formed on the green body of the porous support, and these are simultaneously fired. Has been applied. Since the porous support used for SOFC has a relatively large pore diameter, when a solid electrolyte membrane is formed on the surface after firing, the solution (slurry or sol) for film formation soaks into the pores. When trying to obtain a thin film thickness, it is difficult to obtain a continuous film. In the case of an unfired molded body, since the pores formed between the raw material particles are blocked with an organic compound such as a resin binder, excessive penetration of the solution is suppressed. If fired, the solid electrolyte thin film can be easily formed on the porous support.

In such a production method by simultaneous firing, generally, the firing temperature of the solid electrolyte membrane is set to 1400 (° C.) or less so that densification does not proceed excessively. Therefore, the above firing method cannot be applied to a porous support that requires high temperature firing. For example, the firing temperature of the porous support described in Patent Documents 3 and 4 is 1500 (° C.) or higher. On the other hand, it is conceivable to lower the sintering temperature of the porous support by adding a sintering aid such as MgO or SiO _2, but these sintering aids added to the support material Has a problem of diffusing into the solid electrolyte membrane and deteriorating the membrane characteristics. A similar problem arises in an anode support made of zirconia-NiO, and therefore, a raw material for an anode support that can be sintered at a low temperature with high purity without adding a sintering aid has been desired.

  The present invention has been made against the background described above, and its purpose is to provide a raw material for an anode support that can be obtained with high purity and high strength even by low-temperature firing, and has high porosity, high purity, and high strength. It is to provide a method for manufacturing an anode support.

In order to achieve such an object, the gist of the raw material for an anode support of the first invention is that an anode provided with a solid electrolyte layer sandwiched between it and a cathode layer in order to constitute a solid oxide fuel cell. A raw material for producing a support, wherein (a) fused zirconia particles having an average particle diameter of 10 to 50 (μm), and (b) fixed on the surface of the fused zirconia particles in units of particles. And a nickel (II) oxide fine powder having a specific surface area of 1 to 12 (m ² / g).

  The gist of the manufacturing method of the anode support of the second invention for achieving the above object is that a solid electrolyte layer is sandwiched between the cathode layer and the solid oxide fuel cell. A method for producing an anode support, comprising: (a) a molding step for molding the anode support raw material of the first invention into a predetermined shape; and (b) a maximum of 1400 (° C.) or less in the obtained molded body. And a firing step of performing a firing treatment at a holding temperature.

According to the first invention, the anode support raw material has a specific surface area of 1 to 12 (m ² / g) on the surface of high-strength fused zirconia particles having an average particle size of 10 to 50 (μm). Highly active nickel oxide (II) is fixed in particle units, so the nickel oxide (II) has high sinterability, so a sintering aid such as MgO or SiO ₂ is added to the raw material. Even if not, high strength can be obtained by firing at a low temperature of 1400 (° C.) or lower. Therefore, the raw material for an anode support of the first invention is suitably used for an application in which a solid electrolyte thin film is formed on an unfired porous anode support molded body and these are simultaneously fired, while being highly pure. An anode support having a high porosity and high strength can be obtained even by low-temperature firing. In the present application, nickel oxide is all divalent nickel (II) oxide.

  Further, according to the second invention, in the molding step, a molded body having a predetermined shape is formed from the anode support raw material of the first invention, and in the firing step, the molded body is fired at a temperature of 1400 (° C.) or less. By performing the treatment, an anode support is obtained. Since the nickel oxide fine powder is fixed on the surface of the electrofused zirconia particles, the above raw material has high sinterability due to the highly active nickel oxide fine powder, and is fired at a low temperature without adding a sintering aid. And having a high porosity and high mechanical strength. In addition, since the anode support is manufactured by low-temperature firing, it is easy to cope with low cost, high performance, and thin film by laminating the electrolyte material on one side of the green body and firing it simultaneously. There are also advantages.

  The average particle diameter is a value measured by a laser particle diameter measuring device, and the specific surface area is calculated by measuring the surface area with a gas adsorption measuring device. If the average particle size of the electrofused zirconia particles is less than 10 (μm), it is difficult to obtain a porosity of 25 (%) or more which is preferable for the anode support because the particle size is too small. If the average particle size exceeds 50 (μm), the particle size is too large, and it becomes difficult to obtain a bending strength of 20 (MPa) or more, which is preferable for the anode support.

In addition, it is not sufficient that the nickel oxide fine powder is mixed with the electrofused zirconia particles, and it is necessary that the nickel oxide fine powder is fixed to the surface in units of particles. Fine nickel oxide fine powder with a specific surface area of 1 to 12 (m ² / g) is easy to agglomerate and poor in dispersibility. By simply mixing, the agglomerated grains are unevenly distributed among the fused zirconia particles and sintered. Sex cannot be enhanced sufficiently. “In units of particles” means that the nickel oxide fine powder is ideally fixed to the surface of the electrofused zirconia particles in an independent state, but unless the surface area is significantly reduced. It is also acceptable that the nickel oxide fine powder is agglomerated or adhered to each other. The specific surface area of the nickel oxide fine powder is a value before being fixed to the electrofused zirconia particles. Since the nickel oxide fine powder can be deformed when it is fixed to the surface of the fused zirconia particles, its specific surface area can also change, but it is difficult to measure the specific surface area of the nickel oxide fine powder in the fixed state. In this case, the specific surface area of the nickel oxide fine powder is the value before fixing. The nickel oxide fine powder has, for example, a substantially spherical shape, but a distorted shape having large irregularities is preferable because it has a large surface area and high activity.

  In addition, according to the first and second inventions, since the electrofused zirconia particles have a higher strength than the sintered crystal grains, the sinterability is enhanced by the action of the nickel oxide fine powder. Thus, an anode support having higher mechanical strength can be obtained. Moreover, since the surface irregularities of the electrofused zirconia particles are larger than those of the sintered crystal grains, the raw material having the nickel oxide fine powder fixed on the surface has a large gap formed at the contact portion between the particles. Is more suitable as an anode support material since a large number of communicating pores are formed. In addition, as the zirconia powder having a large average particle diameter, instead of the electrofused zirconia particles, for example, a granulated powder as described in Patent Document 5 may be used. It is crushed during the process of fixing the nickel oxide fine powder. Therefore, in order to obtain both porosity and mechanical strength, it is necessary to use electrofused zirconia particles.

  Here, preferably, the nickel oxide fine powder is fixed to the surface of the electrofused zirconia particles by any one of an impact fixing method, a spray granulation method, and a sol-gel method. According to these fixing methods, agglomeration is suppressed even in the case of fine powder, so that the raw material for anode support fixed to the surface of the fused zirconia particles can be obtained without substantially impairing the large specific surface area of the nickel oxide fine powder. Obtainable.

  In the impact fixing method, the raw material, that is, the mother particle serving as a nucleus and the child particles to be fixed are put into an impact fixing device, and the raw material is dispersed in a high-speed air stream, and a dry process is performed using a force mainly composed of an impact force. The child particles are fixed on the surface of the mother particles. The impact fixing device is composed of, for example, a rotor that rotates at a high speed, a stator, and a circulation circuit, and mechanical actions such as impact force, compression, friction, and shear force are repeated while the raw material that has been charged is dispersed. By receiving, the child particles are fixed (or film-formed) on the surface of the mother particles. According to such an impact fixing method, there is an advantage that the child particles are firmly fixed to the mother particles in a short time of about 3 to 5 minutes without agglomeration.

  In addition, the spray granulation method is, for example, according to a treatment method similar to that described in Patent Document 4, and after the electrofused zirconia particles are crushed in a rotating container, a dispersion containing nickel oxide fine powder is used. By spraying the liquid and heating, the nickel oxide fine powder is fixed to the surface of the electrofused zirconia particles.

  In the sol-gel method, for example, a nickel aqueous solution is mixed with a dispersion of electrofused zirconia particles to deposit nickel oxide fine powder on the surface of the electrofused zirconia particles. In the sol-gel method, since the particle size and other physical properties of the fine particles deposited can be easily controlled depending on the solution concentration and other conditions, a raw material in which nickel oxide fine powder is fixed on the surface of the fused zirconia particles can be obtained by such a manufacturing method. can get.

  Preferably, the average particle diameter D of the electrofused zirconia particles and the specific surface area SA of the nickel oxide fine powder satisfy D / SA of 4 or more and 8 or less. In this way, a raw material with higher strength and porosity can be obtained.

  Preferably, the fused zirconia particles and the nickel oxide fine powder are included in a mass ratio within a range of 7: 3 to 5: 5. If the nickel oxide fine powder is contained in a ratio of 7: 3 or more, it is sufficient for imparting conductivity to the anode support and promoting the sintering of the raw material. Since the amount of fused zirconia particles is sufficiently large, sufficient characteristics can be obtained as an anode support made of an electrolyte material. The electrofused zirconia particles and the nickel oxide fine powder are preferably in a volume ratio of 4: 6 to 6: 4, for example, a ratio of about 5: 5.

Also, preferably, the fused zirconia particles, scandia of 3 to 8 (mol%) of yttria (Y ₂ O ₃₎ yttria dissolved therein in a solid state stabilized zirconia (YSZ), 3~11 (mol% ) A stabilized zirconia in which an appropriate compound such as scandia-stabilized zirconia in which (Sc ₂ O ₃ ) is dissolved is dissolved.

  Preferably, the anode support has a porosity of 25 (%) or more. It is desired that the anode support has a sufficiently high porosity to allow permeation of fuel gas efficiently. If the porosity is 25 (%) or more, it can be said that the fuel gas permeation performance is sufficient.

  Preferably, the anode support has a three-point bending strength of 15 (MPa) or more. Since the anode support is desired to be as strong as possible so that it does not easily break during the manufacturing process or use (for example, when assembling the equipment), it must have a three-point bending strength of 15 (MPa) or more. Is desirable.

  The anode support raw material of the first invention and the anode support produced using the same are suitably used as a constituent material of an anode-supported solid oxide fuel cell.

It is a figure which shows typically 1 particle | grains of the raw material for anode supports of one Example of this invention. It is sectional drawing which shows typically an example of a fuel cell provided with the anode support body manufactured using the raw material of FIG. It is an example of the manufacturing process of the anode support body shown by FIG. It is a figure which shows the cross-section of the impact fixing apparatus used for the adhering process of FIG. It is a figure explaining the structure of the spray granulation apparatus which can be used instead of the impact fixing apparatus of FIG. 4 in the fixing process of FIG.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

FIG. 1 is a diagram showing one grain of an anode support material 10 according to an embodiment of the present invention. In FIG. 1, this raw material 10 is constituted by a nickel oxide powder 14 being fixed to the surface of an electrofused zirconia powder 12. The electrofused zirconia powder 12 is made of, for example, YSZ containing 8 (mol%) yttria, and the average particle diameter is, for example, about 15 (μm). The nickel oxide powder 14 is made of, for example, NiO and has an average particle diameter of about 0.3 (μm) and a specific surface area of about 6 (m ² / g). The fixed amount of the nickel oxide powder 14 is within a range of 5: 5 to 7: 3, for example, about 6: 4 in terms of mass ratio of the electrofused zirconia powder 12 and the nickel oxide powder 14, and in a volume ratio of 4: 6 to 6-6. : 4, for example, about 5: 5. The electrofused zirconia powder 12 and the nickel oxide powder 14 both have irregularities on the surface and have a distorted shape. However, in FIG. 1, the surface is simply formed into a substantially spherical shape. I'm drawing.

  FIG. 2 is a diagram schematically showing a cross-sectional structure of an anode-supported solid oxide fuel cell 18 including an anode support 16 manufactured using the anode support material 10 described above. In FIG. 2, a single cell 20 of the fuel cell 18 has a flat plate shape in which an anode support 16 and a cathode layer 22 are stacked via an electrolyte layer 24, and a plurality of single cells 20 are connected via an interconnector 26. As a result, the fuel cell 18 having a stack structure is formed. Although FIG. 2 shows a state in which two single cells 20 are stacked, the number of stacked layers is appropriately determined by the output voltage and the required voltage of the single cells 20.

  The anode support 16 is made of NiO—YSZ formed from the raw material 10 and has a thickness dimension of about 0.5 to 1.0 (mm), for example. The anode support 16 is a porous body having a large number of open pores that communicate with each other in the thickness direction and open on both surfaces. The porosity is, for example, about 20 to 40 (%), and the three-point bending strength is 18 to 40 ( MPa). Thus, the anode support 16 made of NiO—YSZ and having a high porosity and high mechanical strength functions as a fuel electrode and also functions as a support for ensuring the mechanical strength of the single cell 20.

Further, the cathode layer 22, for example LaSrMnO _3, made of a LaSrCoFeO lanthanum perovskite compounds such as _3, for example, comprises a 10 to 30 ([mu] m) thickness on the order of dimension. The cathode layer 22 is a porous body having a large number of open pores communicating with each other in the thickness direction and opening on both surfaces, and has a porosity of, for example, about 20 to 40 (%).

  The electrolyte layer 24 is made of an electrolyte material such as stabilized zirconia or ceria such as YSZ, and has a thickness of about 10 (μm), for example, and is dense enough not to allow fuel gas or air to pass therethrough. It is structured to quality.

  The interconnector 26 includes a large number of fuel gas flow paths 28 on the anode support 16 side and a large number of air flow paths 30 on the cathode layer 22 side. The fuel gas flow path 28 and the air flow path 30 are formed along directions orthogonal to each other and open to both side surfaces of the interconnector 26, and the fuel gas and air supplied from the side surfaces are supplied to the flow path 28, The anode support 16 and the cathode layer 22 are supplied via 30.

  FIG. 3 is a process diagram for explaining an example of a manufacturing method for manufacturing the anode support 16 provided in the fuel cell 18 configured as described above using the raw material 10 described above. In the fixing process P1, the fused zirconia powder 12 and the nickel oxide powder 14 are prepared, and the nickel oxide powder 14 is fixed to the surface of the fused zirconia powder 12 serving as a base material by using, for example, an impact fixing method.

  FIG. 4 shows an example of the structure of an impact fixing device 32 (for example, a hybridization system manufactured by Nara Machinery Co., Ltd.) used in the impact fixing method. In FIG. 4, the impact fixing device 32 includes a rotor 34 that rotates at high speed coaxially in a cylindrical stator 36, and a workpiece 38 that is directed outward by the rotation of the rotor 34. A circulation circuit 40 for returning to the center of the circuit is provided. For example, eight blades 42 are attached to the outer peripheral edge portion of the rotor 34 at equal intervals in the circumferential direction, and an air flow is formed on the inner periphery of the stator 36 by rotating the rotor 34. A material charging path 48 including a charging port 44 and a valve 46 is provided toward the inner periphery of the stator 36. When the valve 46 is opened, the workpiece 38 is fed into the stator 36 from the charging port 44. The stator 36 is provided with a jacket 50, and cooling or heating is possible by passing a fluid (for example, hot water) adjusted to a desired temperature through the space. Reference numeral 52 denotes a discharge port. The workpiece 38 is discharged from the discharge port 52 by raising the discharge valve 54 to a position indicated by a broken line, for example.

  In this embodiment, the workpiece 38 is a fused zirconia powder (mother particles) serving as a base material and nickel oxide powder (child particles) fixed to the surface thereof, and such materials are handled. Therefore, a portion in contact with the material such as the inner surface of the stator 36 is made of a cemented carbide such as a ceramic coating or WC, and has high wear resistance.

  In the fixing step P1, the object to be processed 38, that is, the electrofused zirconia powder 12 that is the mother particle and the nickel oxide powder 14 that is the child particle are transferred to the impact fixing device 32 configured as described above while rotating the rotor 34. And PMMA (polymethylmethacrylate) are introduced into the machine through the inlet 44. The charged workpiece 38 is sent to the central portion of the stator 36 via the material charging path 48 and receives a circumferential force from the blade 42 of the rotating rotor 34, so that it receives an impact force while being dispersed. Repeatedly receives mechanical action such as compression, friction and shearing force. As a result, the nickel oxide powder 14 is fixed to the electrofused zirconia powder 12. The workpiece 38 introduced into the stator 36 enters the circulation circuit 40 opened on the inner peripheral surface of the stator 36, and returns to the center portion of the stator 36 through this. Therefore, since the workpiece 38 is repeatedly subjected to the mechanical action while circulating inside the apparatus, the raw material 10 in which the nickel oxide powder 14 is fixed to the electrofused zirconia powder 12 can be obtained efficiently in a short time. The PMMA is added so that the child particles are easily fixed to the mother particles. For example, the addition amount is 0.75 (wt%), but it is not always necessary to add the PMMA.

The above processing is performed, for example, in 5 minutes while rotating the rotor 34 at a rotational speed of 5000 (min ⁻¹ ) and a peripheral speed of 60 (m / s). This processing time is determined so that the entire amount of the nickel oxide powder 14 is fixed to the electrofused zirconia powder 12. When the discharge valve 54 is opened after the scheduled time has elapsed, the raw material 10 is discharged from the discharge port 52 and is collected. After the entire amount is collected, the rotation of the rotor 34 is stopped.

  Returning to FIG. 3, in the granulation step P <b> 2, a binder is added to the recovered raw material 10, stirred, and granulated by an appropriate method such as spray drying. For example, a PVA (polyvinyl alcohol) aqueous solution or the like can be used as the binder. The addition amount is appropriately determined according to the size, shape, etc. of the molded product to be produced, and is, for example, 5 to 10 (wt%). In this embodiment, as described above, since PMMA is added when the nickel oxide powder 14 is fixed and the raw material 10 is produced as described above, it can be pressure-molded as it is. The aqueous solution may not be added. That is, the granulation step P2 can be omitted.

  Next, in the molding step P3, a thin plate-shaped molded body is obtained by a pressure molding apparatus such as a uniaxial pressure molding apparatus or a roll pressure molding apparatus. The molding pressure is appropriately determined according to the desired porosity and mechanical strength of the anode support 16, and is, for example, about 50 (MPa). Next, in the firing step P4, for example, in an oxidizing atmosphere, this is subjected to a firing treatment under conditions of a maximum holding temperature of 1400 (° C.) and a holding time of about 2 hours. Thereby, the said anode support body 16 which is a porous thin plate is obtained.

  In the above manufacturing method, the fixing step P1 can be performed using another manufacturing apparatus instead of the impact fixing apparatus 32. FIG. 5 shows a spray granulation apparatus 60 which is an example of another production apparatus.

  The spray granulating apparatus 60 is supported by a rocking table 64 in a state in which a chamber 62 is rotatable about its axis extending along a substantially horizontal direction. For example, four wheels 66 for supporting 62 from diagonally below are provided. Two wheels 66 are provided on the near side and two on the far side of the chamber 62 in FIG. 5, respectively, and two on the near side are shown in FIG. The four wheels 66 are configured to be capable of rotating about rotation axes extending in a substantially horizontal direction and parallel to each other, and the chambers 62 supported by the four wheels 66 are supported by being rotated in synchronization with each other. Is rotated about its axis.

  The rocking table 64 is supported by the fixed table 70 so as to be rockable about the rocking shaft 68. Therefore, the chamber 62 is swung so that both ends in the axial direction are alternately raised and lowered with the swing of the swing base 64.

  Moreover, the crushing blade | wing 72 is provided in the right end part in the chamber 62 in FIG. The crushing blade 72 is attached to a rotation shaft of a crushing motor 74 disposed on the right side of the chamber 62 and is rotated at a rotation speed determined independently of the rotation speed of the chamber 62. The crushing motor 74 is swung together with the chamber 62, but its support structure is omitted.

  Further, a spray nozzle 76 and an exhaust port 78 are provided above the central portion in the chamber 62, and these pipes protrude from the right end portion of the chamber 62 to the outside. The spray nozzle 76 is for sending a liquid from the outside into the chamber 62 for spraying. As shown by the wavy line in FIG. 5, the spray angle is a wide angle of about 90 degrees, for example. The exhaust port 78 is for exhausting the steam generated in the chamber 62 to the outside, and a filter (not shown) for preventing the internal powder from being sucked and exhausted is attached to the opening. It has been.

  A plurality of infrared heaters 80 are provided on the outer periphery of the chamber 62 so that the inside of the chamber 62 can be heated to a desired temperature.

  When the raw material 10 is manufactured using the spray granulator 60 configured as described above, for example, the lid 82 of the chamber 62 provided at the left end of FIG. 5 is opened and the fused zirconia powder 12 is put therein. To do. Note that the input amount is set such that, for example, about 1/3 of the radial direction of the crushing blade 72 is hidden. Next, for example, while heating the inside of the chamber 62 to a temperature of about 100 (° C.), the wheel 66 is rotated to rotate the chamber 62 around the axis, and the swing table 64 is swung. At the same time, the crushing motor 74 is driven to rotate the crushing blades 72. Thereby, the electrofused zirconia powder charged into the chamber 62 is crushed by the crushing blades 72 in a heated state.

  Subsequently, the dispersion liquid of the nickel oxide powder 14 is sprayed from the spray nozzle 76 while the rotation and heating of the chamber 62 and the crushing blades 72 are continued. Even after spraying, the rotation and heating of the chamber 62 and the crushing blades 72 are continued. Thereby, the liquid component of the nickel oxide powder dispersion is evaporated and discharged from the exhaust port 78, and the nickel oxide powder is mixed with the electrofused zirconia powder. The PVA aqueous solution is sprayed from the spray nozzle 76 onto the mixed powder while the rotation and heating of the chamber 62 and the crushing blade 72 are continued. As the PVA aqueous solution, for example, a solution obtained by dissolving PVA in pure water at a concentration of about 5 to 10 (wt%) is used. At this time, spraying is performed from a spray nozzle 76 at a wide angle of, for example, about 30 to 90 degrees so that the PVA aqueous solution is supplied as widely as possible. Even after the spraying of the PVA aqueous solution, the rotation and heating of the chamber 62 and the crushing blades 72 are continued, so that water gradually evaporates from the PVA aqueous solution that has entered the mixed powder, and the viscosity increases. The nickel oxide powder 14 is fixed to the surface of the fused zirconia powder 12, and the raw material 10 similar to that shown in FIG. 1 is obtained.

  Table 1 below summarizes the results of manufacturing and evaluating the anode support 16 under various changes in the manufacturing process shown in FIG. 3 together with Comparative Examples 1 to 9 outside the scope of the present invention. Is. In Table 1, the average particle size of the fused zirconia powder 12 measured with a laser particle size measuring device is measured in the “electrofused zirconia” column, and the gas adsorption type measurement device is measured in the “NiO specific surface area” column. The specific surface area of the nickel oxide powder 14 is shown in the “D / SA” column, and the ratio of the particle size D of electrofused zirconia to the specific surface area SA of NiO is shown in the “NiO addition amount” column for Examples 1 to 5 only. The numerical value is the amount of the nickel oxide powder 14 with respect to the whole raw material, the subsequent European letters in parentheses indicate the fixing method, and the “porosity” and “three-point bending strength” columns are obtained by pressure molding and firing treatment. The porosity and three-point bending strength of the anode support 16 are shown respectively. The method of fixing the nickel oxide powder 14 was “S” for the impact fixing device 32 and “H” for the spray granulation device 60. “K” is due to dry mixing. The porosity was measured with a mercury intrusion porosimeter, and the three-point bending strength was measured according to JIS R1601.

  In Table 1 above, Comparative Examples 1 and 2 are anode support 16 produced using electrofused zirconia powder 12 to which nickel oxide powder 14 is not fixed. In Comparative Examples 3 to 5, when the electrofused zirconia powder 12 is granulated, the nickel oxide powder 14 is mixed in a dry manner before the liquid is added. In Comparative Examples 6 to 9, raw materials were prepared in the same manner as in the Examples except that the fused zirconia powder 12 having an average particle diameter of 5 (μm) or 100 (μm) was used.

According to the above evaluation results, the electrofused zirconia powder 12 having an average particle size in the range of 10 to 50 (μm) is used, and the nickel oxide powder 14 having a specific surface area of 7 to 12 (m ² / g). When the raw material 10 fixed at a ratio of 30 to 50 (wt%) is used, the porosity is in the range of 25 to 35 (%) and the three-point bending strength is in the range of 20 to 38 (MPa). A sufficiently high anode support 16 can be obtained. Further, in the case of using the raw material 10 manufactured by the impact fixing device 32 and the case of using the raw material 10 manufactured by the spray granulating device 60, the porosity is 25 (%) or more and the three-point bending strength is 20%. An anode support 16 having excellent characteristics of (MPa) or more was obtained.

  On the other hand, Comparative Examples 1 and 2 were produced by using the same fused zirconia powder 12 as in Examples 1 to 4 without attaching nickel oxide powder 14 thereto. In Comparative Examples 1 and 2, an extremely high porosity of 38 to 40 (%) was obtained, but the three-point bending strength remained below 5 (MPa). In the specification in which the nickel oxide powder 14 is not added, it is considered that strength is not obtained because sintering is not performed at the maximum holding temperature of 1400 (° C.) described above.

  In Comparative Examples 3 to 5, nickel oxide powder 14 is dry-mixed. In these cases, when the porosity is increased, the strength is lowered, and conversely, when the strength is secured, the porosity is decreased. Unless the nickel oxide powder 14 is fixed to the fused zirconia powder 12 in advance, it is difficult to satisfy the porosity and the bending strength at the same time. The average particle diameter of the nickel oxide powder 14 of Comparative Example 3 is 0.5 (μm), which is larger than that used in Example 1 above. In Comparative Example 3, the low bending strength may also have an effect.

In Comparative Examples 6 to 9, electrofused zirconia powder 12 having an average particle size of 5 (μm) or 100 (μm) is used. About each, the specific surface area of the nickel oxide powder 14 was as small as 1 (m ² / g) and as large as 12 (m ² / g), and was evaluated. When the average particle diameter of the electrofused zirconia powder 12 is 5 (μm) and the specific surface area of the nickel oxide powder 14 is 1 (m ² / g), an extremely high bending strength of about 60 (MPa) can be obtained. The porosity was remarkably insufficient at 15 (%). Further, when the average particle size of the electrofused zirconia powder 12 is 5 (μm) and the specific surface area of the nickel oxide powder 14 is 12 (m ² / g), a higher bending strength of about 85 (MPa) can be obtained. On the other hand, the porosity was remarkably insufficient at 12%. When the average particle diameter of the electrofused zirconia powder 12 is decreased, the bending strength is increased. By using the nickel oxide powder 14 having a large specific surface area, a higher bending strength can be obtained. %) Is not suitable as a raw material for an anode support for which a high porosity is desired. When the average particle diameter of the electrofused zirconia powder 12 is 100 (μm), the specific surface area of the nickel oxide powder 14 is 1 (m ² / g) or 12 (m ² / g). Although the porosity was extremely high, the bending strength could not be obtained. As the average particle size of the electrofused zirconia powder 12 is larger, it becomes easier to ensure the porosity. However, when the particle size is increased to 100 (μm), the sinterability is remarkably deteriorated. Even if it is used, bending strength cannot be obtained.

  According to the above results, in order to obtain a porosity of 25 (%) or more, it is necessary to use the electrofused zirconia powder 12 having an average particle size of 10 (μm) or more, and further, 20 (MPa) In order to obtain the above bending strength, it is necessary to use the electrofused zirconia powder 12 having an average particle size of 50 (μm) or less. Further, even if both the electrofused zirconia powder 12 and the nickel oxide powder 14 are used, unless the nickel oxide powder 14 is fixed to the surface of the electrofused zirconia powder 12 to constitute the raw material 10, the porosity and bending strength are increased. Both cannot be satisfied.

Also, according to Table 1 above, in Examples 3 and 4, very good results were obtained with a porosity of 30 (%) or more and a three-point bending strength of 25 (MPa) or more. These have D / SA of 4.17 and 7.14, respectively. That is, the particle diameter D of the electrofused zirconia powder 12 is 10 to 50 (μm), the nickel oxide (II) powder 14 has a specific surface area SA of 1 to 12 (m ² / g), and 4 ≦ D / SA ≦ 8. It is particularly preferred that

In short, according to the present embodiment, the anode support raw material 10 has a specific surface area of 1 to 12 (m ² ) on the surface of the high-strength fused zirconia powder 12 having a large average particle size of 10 to 50 (μm). / g) and the highly active nickel oxide powder 14 is fixed, so that the nickel oxide powder 14 has a high sinterability, so that no additional sintering aid is added. High strength can be obtained by firing at the following low temperature. Therefore, the anode support raw material 10 is suitably used for an application in which an electrolyte layer 24 is formed on an unfired molded body for constituting the anode support 16, and these are simultaneously fired. Even with low temperature firing, high porosity and high strength can be obtained.

  Further, according to this example, a molded body is molded from the anode support raw material 10 in the molding step P3, and subjected to a firing treatment at 1400 (° C.) in the firing step P4. 16 is obtained. Since the raw material 10 has the nickel oxide powder 14 fixed on the surface of the electrofused zirconia powder 12, the highly active nickel oxide powder 14 has high sinterability, so that it is not necessary to add a sintering aid. It can be fired at a low temperature, has a high porosity, and has a high mechanical strength. In addition, since the anode support 16 is manufactured by low-temperature firing, by laminating an electrolyte material on one surface of the unfired molded body and simultaneously firing, it is possible to cope with cost reduction, high performance, and thin film formation. There is also an easy advantage.

  As mentioned above, although this invention was demonstrated in detail with reference to drawings, this invention can be implemented also in another aspect, A various change can be added in the range which does not deviate from the main point.

10: Raw material for anode support, 12: Electrofused zirconia powder, 14: Nickel oxide powder, 16: Anode support, 18: Solid oxide fuel cell, 20: Single cell, 22: Cathode layer, 24: Electrolyte layer , 26: interconnector, 28: fuel gas flow path, 30: air flow path, 32: impact fixing device, 34: rotor, 36: stator, 38: workpiece, 40: circulation circuit, 42: blade, 44: Input port, 46: valve, 48: material input path, 50: jacket, 52: discharge port, 54: discharge valve, 60: spray granulator, 62: chamber, 64: swing base, 66: wheel, 68: Oscillating shaft, 70: fixed base, 72: crushing blade, 74: crushing motor, 76: spray nozzle, 78: exhaust port, 80: infrared heater, 82: lid

Claims (5)

A raw material for producing an anode support provided with a solid electrolyte layer sandwiched between a cathode layer to constitute a solid oxide fuel cell,
Fused zirconia particles having an average particle size of 10 to 50 (μm),
And a nickel (II) oxide fine powder having a specific surface area of 1 to 12 (m ² / g) fixed on the surface of the electrofused zirconia particles in units of particles. .   The raw material for an anode support according to claim 1, wherein the nickel (II) fine powder is fixed on the surface of the fused zirconia particles by any one of an impact fixing method, a spray granulation method and a sol-gel method.   The raw material for an anode support according to claim 1, wherein an average particle diameter D of the electrofused zirconia particles and a specific surface area SA of the nickel oxide (II) fine powder satisfy 4≤D / SA≤8.   The raw material for an anode support according to claim 1, wherein the electrofused zirconia particles and the nickel (II) oxide fine powder are contained in a mass ratio within a range of 7: 3 to 5: 5. A method for producing an anode support provided to sandwich a solid electrolyte layer with a cathode layer in order to constitute a solid oxide fuel cell,
A molding step of molding the anode support raw material according to any one of claims 1 to 4 into a predetermined shape;
And a firing step in which the obtained molded body is subjected to a firing treatment at a maximum holding temperature of 1400 (° C.) or less.

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