JP2011170982A - Fuel cell separator, its manufacturing method, and its member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a separator having an excellent mass-productivity, capable of improving supply characteristics of a hydrogen source such as hydrogen gas, methanol, ethanol or the like and an oxygen source such as air or the like, and improving exhausting characteristics of moisture content, and reducing contact resistance, in which a slurry containing metal powder or a compound are laminated on a metal plate before being sintered to make powder filling work efficient as well as to make possible a thickness control, and moreover, spherical metal powders between themselves, and the spherical metal powder and the metal plate, can be metallic-bonded by sintering. <P>SOLUTION: In the manufacturing method of a separator for a fuel cell, a slurry containing a metallic powder or a compound containing a metallic powder is laminated in a sheet shape on a metal plate, and then the metallic powder itself, and the metallic powder and the metal plate are mutually metallic-bonded by sintering to integrally form a porous body of a sheet shape made of the metallic powder on the metal plate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel cell separator, a manufacturing method thereof, and a member thereof.

  In recent years, a fuel cell using a water generation reaction has attracted attention as a clean energy source friendly to the global environment. The structure of the fuel cell usually has a catalyst layer so that the electrolyte membrane is sandwiched from both sides, and the microporous layer, the diffusion layer, the separator channel, or The separator including the flow path is positioned.

  Among these, as an important role common to the microporous layer, the diffusion layer, the separator channel, or the channel provided in the separator, a hydrogen source such as hydrogen gas, methanol, and ethanol, and an oxygen source such as air are used. There is a function of supplying the catalyst layer as a reaction field and a function of discharging the generated water component. Furthermore, there is an important function of taking out the electrons generated by the chemical reaction to the external circuit for output as efficiently as possible. Therefore, it is very important to reduce the contact resistance by maintaining good adhesion to the catalyst layer, which is a reaction field, and good adhesion between the microporous layer, the diffusion layer, and the separator flow path.

  For the above microporous layer and diffusion layer, a porous carbon material is generally used. As for the separator channel, a carbon or metal channel channel formed by cutting or pressing is generally used. However, all of these have problems such as supply of a hydrogen source and oxygen source, discharge of water, and increased contact resistance, and there is a need to improve them.

  For example, as disclosed in Japanese Patent Application Laid-Open No. 2004-186116 (Patent Document 1), it relates to a method for manufacturing a diffusion layer of a fuel cell aimed at reducing electric resistance. It is characterized by a technique using a foam metal porous body in which pores are formed in an annular mouth, and is greatly different from the present invention. In the present invention, the portion corresponding to the annular port in the above document is a spherical metal powder, and the portion corresponding to the skeleton of the foam metal porous body other than the annular port is a pore surrounded by the spherical metal powder. It takes the exact opposite structure. This makes it possible to improve supply characteristics / discharge characteristics and reduce contact resistance.

  In general, foam metal uses (1) a method in which a gas is blown into a molten metal to solidify at the same time as formation of bubbles, or (2) a foaming agent is added to the molten metal and gas generation by decomposition of the foaming agent is utilized. Because of the manufacturing method, the pores are actually partitioned by the cell walls, and the closed pore type that is separated and independent from each other has a basic structure, so that the internal mass mobility is generally inferior. In addition, when connecting holes are obtained by controlling the manufacturing method, the porosity tends to be large, so the strength as a structure is inferior. There is a problem that the hole portion is easily compressed and deformed, and sufficient mass mobility cannot be obtained. Furthermore, even when the communication hole is formed in the cell wall by a secondary action such as rolling or compression, there is a problem in that it is inferior in mass mobility such as gas or liquid because it is different from the complete open pore type.

For example, as disclosed in Japanese Patent Application Laid-Open No. 2009-252399 (Patent Document 2), the Patent Document 2 has been studied by the inventors so far. A porous body using spherical metal powder with a separator channel structure and a separator channel structure having a function of a diffusion layer aiming to reduce supply characteristics of hydrogen source and oxygen source, water discharge characteristics and contact resistance However, this Patent Document 2 does not mention a manufacturing method aimed at improving mass productivity.
JP 2004-186116 A JP 2009-252399 A

  As described above, in the case of the cited document 1, improvement of supply characteristics / discharge characteristics and reduction of contact resistance are insufficient. Also, cited document 2 aims to reduce the supply characteristics of hydrogen source and oxygen source, the discharge characteristics of water, and the contact resistance, and the function of the separator channel structure and the diffusion layer with a porous body using spherical metal powder. Although it is the separator channel structure provided, the solution of the point of productivity improvement is unknown.

  As a result of diligent development to solve the above problems, the supply characteristics of hydrogen sources such as hydrogen gas, methanol and ethanol, and oxygen sources such as air, and the discharge characteristics of water components are improved, and When manufacturing a separator for a fuel cell that enables reduction of contact resistance, a slurry or compound containing metal powder is laminated on a metal plate before sintering to improve the efficiency of powder filling, The present invention also provides a method for producing a separator for a fuel cell that is excellent in mass productivity, in which spherical metal powders and spherical metal powders and metal plates are bonded to each other by sintering.

The gist of the invention is that
(1) In manufacturing a fuel cell separator, a slurry containing a metal powder or a compound containing a metal powder is laminated in a sheet form on a metal plate, and then sintered with metal powders and a metal powder. A manufacturing method characterized in that a sheet-like porous body made of metal powder is integrally formed on a metal plate by metal bonding of the metal plates to each other.

(2) The fuel cell separator according to (1), wherein two or more slurries or compounds having different powder particle size ranges of the metal powder are laminated on a metal plate. Manufacturing method.
(3) The method for producing a fuel cell separator according to (1) or (2), wherein a slurry containing a metal powder or a compound is laminated on both surfaces of a metal plate.

(4) A method for producing a fuel cell separator, wherein the powder according to any one of (1) to (3) is a spherical powder.
(5) A method for producing a fuel cell separator, wherein the metal powder according to any one of (1) to (4) is produced by an atomizing method.

(6) With respect to the porous body portion on the sintered metal plate obtained by the method according to any one of (1) to (5), in any 1 mm ^{2 on the} sheet surface perpendicular to the thickness direction A fuel cell separator characterized by having at least one hole having a cross-sectional area of 0.001 mm ² or more and penetrating the porous body portion in the thickness direction.
(7) The separator for a fuel cell obtained by the method according to any one of (1) to (5) above has a diffusion layer, a microporous layer, and these in addition to the functions of the separator and the separator channel. Among them, the fuel cell separator member has one or more functions.

  As described above, according to the present invention, it becomes possible to improve the manufacturability of the separator for a fuel cell using the spherical metal powder. Further, the flow path of the obtained fuel cell separator is composed of porous bodies in which spherical metal powders are joined by metal bonds mainly in the vicinity of the contact points of the spheres and are not bonded to each other on the other surface, and are surrounded by the spheres. As a result, it is possible to secure a sufficient number of connected pores, so that the hydrogen source and oxygen source supply characteristics and the water component discharge characteristics are excellent.

  In addition, since the spherical metal powders are three-dimensionally metal-bonded to form the skeleton of the separator channel, it is excellent in uniform stress dispersibility and high strength, and the catalyst layer, microporous layer, diffusion layer, etc. In contact of the separator with other members, it exhibits excellent three-dimensional adhesion characterized by a spherical shape, and it is possible to reduce contact resistance.

The present invention will be described in detail below.
In the present invention, the slurry may be an aqueous solvent or a non-aqueous solvent using an organic solvent such as alcohol, ketone, saturated fatty acid, chloroethylene, and further contains a dispersant, a binder, a plasticizer, and the like as necessary. It is a waste. Moreover, as a combined containing the spherical metal powder which concerns on this invention, the thing using a polymer, wax, etc. is said, for example.

  In addition to vacuum sintering, sintering in a reducing atmosphere such as hydrogen, sintering in an inert gas such as argon or nitrogen, and atmospheric sintering can be applied. In addition, most of the components other than the spherical metal contained in the slurry or combined are basically removed by sintering, and if there are any remaining components, subsequent cleaning or the like may be performed. Moreover, you may perform roll processing for the purpose of whole thickness and shape control before sintering, or after sintering, press control at the time of sintering, press processing, cutting processing, grinding | polishing processing, etc. as needed.

Moreover, about the porous body part on the metal plate after sintering, in any 1 mm ² on the porous body surface perpendicular to the thickness direction, pores having a cross-sectional area of 0.001 mm ² or more and penetrating the porous body part in the thickness direction By having at least one or more, it becomes possible to improve the discharge characteristics of the water component. Desirably, at least one hole having a cross-sectional area of 0.002 mm ² or more and penetrating the porous body portion in the thickness direction in an arbitrary 0.5 mm ² of the porous body surface perpendicular to the thickness direction. Further, it becomes possible to further enhance the discharge characteristics of the water component.

  Further, the spherical shape of the spherical metal powder does not mean a perfect sphere, but is a sphere that is naturally obtained by an action such as surface tension when solidified from a molten state. Further, if a similar spherical shape is obtained by machining or the like, it is applicable and not limited thereto. In addition, when powder molding is performed from a molten state, the main spherical metal powder includes those in which a fine metal powder, a flat-type fine metal powder, or the like is bonded and adhered. It also has an effect of improving the adhesion between the structure and other members.

  The above atomizing method is suitable for the production of the spherical metal powder, and particularly when the spherical metal powder produced by the gas atomization method is used, the metal powders are sintered mainly in a point contact state, so that they are sufficiently connected to each other. A large pore portion, and excellent mass transfer of liquid and gas flowing through the pore portion can be maintained. Further, the adhesion is improved at the time of contact with other members, and the contact resistance can be reduced. Although the gas atomizing method has been described, the present invention is not necessarily limited to the gas atomizing method, and the present invention is not limited to this as long as the method can obtain a spherical shape or a similar shape to a sphere.

  By applying the optimum sintering temperature, it is possible to perform metal bonding limited to the vicinity of the contact point between the spheres of the spherical metal powder, and it is possible to secure sufficient connection holes after sintering. The optimum sintering temperature at this time varies depending on the particle size of the spherical metal powder. Basically, when a spherical metal powder having a small particle size is used, it is necessary to apply a lower temperature. When this temperature is too high, the sintering of the spherical metal powder proceeds too much, so that the connection holes cannot be obtained.

  Furthermore, with regard to sintering, it is possible to apply stressed press sintering, but when excessive press stress is applied, it is necessary to be careful because there are cases where sufficient connected pores may not be obtained. . In addition, after sintering, if necessary, washing, pickling, etc. can be performed in order to remove the oxide film or the like. Furthermore, after the sintering, it is possible to apply a corrosion-resistant coating, a highly conductive film coating, a water-repellent treatment, a hydrophobic treatment, a new aqueous treatment, or the like after the sintering.

When the porosity of the porous body portion obtained by the present invention is less than 20%, it may be difficult to obtain a sufficient mass mobility of gas or liquid. When the porosity exceeds 60%, the structure is obtained. May be insufficient. Therefore, the porosity is preferably about 20% to 60%, but this is not the case when the substance mobility and strength actually required for each application can be sufficiently satisfied.
The porosity in this case refers to the average volume ratio occupied by the pores in the constant volume of the porous body portion, and is measured by a calculation using a microscopic observation of a cross section, a mercury intrusion method, or the like. Is possible.

  The size of each hole can be controlled by the particle size of the spherical metal powder to be used. Depending on the application, the size of the hole may be different depending on the position in the porous structure. Specifically, it is conceivable that the size of the holes is divided into two stages depending on the position, or that the slopes are distributed in order.

  Various chemical components of the spherical metal powder can be selected according to required corrosion resistance, oxidation resistance, thermal expansion characteristics, thermal conductivity, electrical conductivity, and the like. For example, application of stainless steel, Ni-based corrosion-resistant superalloy, Ni—Cu-based corrosion-resistant alloy, oxidation-resistant alloy, etc. can be considered.

Hereinafter, the present invention will be specifically described by way of examples.
Example 1
After producing a spherical SUS316L powder by gas atomization method, a spherical powder with a particle size of 30-100 μm is collected by classification, and a slurry is prepared by mixing the spherical powder with a dispersion medium, a dispersant, a binder, and a plasticizer. did. The slurry obtained at a predetermined position on a metal plate made of SUS316L having a thickness of 0.2 mm and a length and width of 140 mm × 140 mm subjected to necessary machining to form a fuel supply port, a discharge port, a fastening bolt hole, etc. After being laminated on a sheet having a length and width of 100 mm × 100 mm and a thickness of 0.2 mm by a screen printing method, a temporary molded body was produced through a drying process at 70 ° C. × 60 minutes. Subsequently, the obtained temporary molded body is sintered at 1150 ° C. in a hydrogen reduction atmosphere furnace, thereby obtaining a fuel cell separator in which a porous body made of spherical metal powder is integrated on a metal plate by metal bonding. Obtained. As a result of SEM observation of the obtained member, it was confirmed that the porosity of the porous body portion was about 40%.

(Example 2)
After producing a spherical Fe-26Cr-1Mo (hereinafter, weight%) powder by gas atomization method, a spherical powder having a particle size of 35 to 90 μm is collected by classification, and a dispersion medium, a dispersant, a binder are collected into the spherical powder. Then, a plasticizer was mixed to prepare a slurry. Obtained at predetermined positions on both sides of a SUS316L metal plate with a thickness of 0.2 mm and length and width of 130 mm x 150 mm, which have been machined to form fuel supply ports, discharge ports, fastening bolt holes, etc. on both sides. The obtained slurry was laminated on a sheet having a length and width of 90 mm × 120 mm and a thickness of 0.25 mm by a screen printing method, and then a temporary molded body was produced through a drying process at 50 ° C. × 60 minutes. Next, the obtained temporary molded body was introduced into a continuous furnace in a hydrogen reduction atmosphere, sintered at 1100 ° C., and a separator for a fuel cell in which a porous body composed of spherical metal powders was integrated on both surfaces of a metal plate. Obtained. As a result of observing the obtained member under a microscope, it is a porous structure composed of a skeleton part in which powder particles are bonded to each other and a connecting hole, and in any 1 mm ² on the sheet surface perpendicular to the thickness direction Seven holes having a cross-sectional area of 0.001 mm ² or more and penetrating in the thickness direction were confirmed.

(Example 3)
After producing spherical Fe-35Cr powder by the gas atomization method, two types of spherical powders having different particle size ranges of 20 to 70 μm and 100 to 200 μm are collected by classification, Two kinds of slurries with different powder particle sizes were prepared by mixing a dispersion medium, a dispersant, a binder, and a plasticizer. The slurry obtained was placed at predetermined positions on both sides of a SUS316L metal plate having a thickness of 0.2 mm and a length and width of 200 mm × 250 mm, which had been machined to form fuel supply ports, discharge ports, fastening bolt holes, and the like. Among them, a slurry containing powder having a particle size of 100 to 200 μm was laminated in a sheet shape having a length and width of 150 mm × 200 mm and a thickness of 0.25 mm, and then a temporary molded body was produced through a drying process at 70 ° C. × 30 minutes. Next, another slurry containing a powder having a particle size of 20 to 70 μm was laminated in a sheet shape having a length and width of 150 mm × 200 mm and a thickness of 0.1 mm at predetermined positions on both sides of the obtained temporary molded body, and 70 ° C. × 30 A temporary molded body in which a plurality of slurries were laminated on both surfaces was prepared through a drying process for 1 minute. The obtained temporary molded body is introduced into a hydrogen reducing atmosphere furnace and sintered at 1100 ° C., whereby a plurality of laminated porous bodies composed of spherical metal powders having different particle sizes are formed on both sides of the metal plate. And a fuel cell separator integrated by metal bonding.

Example 4
After producing a spherical Fe-25Cr-20Ni powder by the water atomization method, a spherical powder having a particle size of 150 to 250 μm was collected by classification, and a composite was prepared by using wax for this spherical powder. At a predetermined position on a metal plate made of SUS310 having a thickness of 0.3 mm and a length and width of 160 mm × 260 mm that have been subjected to necessary machining to form a fuel supply port, a discharge port, a fastening bolt hole, etc., After laminating into a sheet shape having a length and width of 120 mm × 220 mm and a thickness of 0.5 mm, a temporary molded body was produced through a drying process. Next, the obtained temporary molded body is introduced into a hydrogen reduction atmosphere furnace and sintered at 1200 ° C. so that a porous body made of spherical metal powder is integrated on a metal plate by metal bonding. A separator was obtained. As a result of microscopic observation of the porous body portion of the obtained member, a porous structure composed of a skeleton portion in a state where powder particles were bonded to each other and a connected hole was confirmed.

(Example 5)
After producing a spherical Fe-33Cu powder by the gas atomization method, a spherical powder having a particle size of 20 to 60 μm is collected by classification, and a dispersion medium, a dispersant, a binder, and a plasticizer are mixed with this spherical powder to form a slurry. Produced. Slurry obtained at a predetermined position on a metal plate made of Fe-33Cu having a thickness of 0.2 mm and a length and width of 70 mm × 70 mm subjected to necessary machining to form a fuel supply port, a discharge port, a fastening bolt hole, etc. Were laminated by a doctor blade method in a sheet shape of 50 mm × 50 mm in length and width of 0.2 mm, and then a temporary molded body was produced through a drying process. Next, the obtained temporary molded body is introduced into a vacuum atmosphere furnace and sintered at 1070 ° C., so that a porous body made of spherical metal powder is integrated on the metal plate by metal bonding. Got. As a result of observing the porous body portion of the obtained member under a microscope, it is a porous structure composed of a skeleton portion in which powder particles are bonded to each other and connected pores, and an arbitrary 1 mm on the sheet surface perpendicular to the thickness direction. ² , 5 holes having a cross-sectional area of 0.001 mm ² or more and penetrating the porous body portion in the thickness direction were confirmed.

(Example 6)
After producing a spherical Ni-16Cr-16Mo-6Fe-3W powder by gas atomization method, a spherical powder having a particle size of 150 to 300 μm is collected by classification, and this spherical powder is dispersed into a dispersion medium, a dispersant, a binder, a plastic. The agent was mixed to prepare a slurry. The slurry obtained was screen-printed at a predetermined position on both surfaces of a 0.2 mm thick SUS316L metal plate subjected to necessary machining to form a fuel supply port, a discharge port, a fastening bolt hole, etc. After laminating into a sheet shape having a length and width of 180 mm × 90 mm and a thickness of 0.5 mm, a temporary molded body was prepared through a drying process at 80 ° C. × 40 minutes. Next, the obtained temporary molded body was introduced into a continuous furnace in a hydrogen reduction atmosphere and sintered at 1100 ° C., so that the porous body composed of spherical metal powder was integrated by metal bonding on both surfaces of the metal plate. A fuel cell separator was obtained. As a result of observing the porous body portion of the obtained member under a microscope, it was confirmed that the porous body was composed of a skeleton portion in which powder particles were bonded to each other and connected pores.

(Example 7)
After producing a spherical Fe-24Cr-1.5Al-1.3Si powder by the gas atomization method, a spherical powder having a particle size of 150 to 250 μm was collected by classification, and a composite was produced using wax for this spherical powder. . The obtained composite was laminated in a sheet shape having a length and width of 50 mm × 100 mm and a thickness of 0.4 mm at a predetermined position on a SUS430 metal plate having a thickness of 0.2 mm subjected to necessary machining. Thereafter, a temporary molded body was produced through a drying step at 100 ° C. for 20 minutes. Next, the obtained temporary molded body is introduced into a hydrogen reduction atmosphere furnace and sintered at 1150 ° C., so that a porous body made of spherical metal powder is integrated on a metal plate by metal bonding. A separator was obtained. As a result of microscopic observation of the porous body portion of the obtained member, it was confirmed that the porous body was composed of a skeleton portion in which powder particles were bonded to each other and a connected pore having a porosity of about 40%. .

As described above, the separator for a fuel cell obtained by the present invention is surrounded by spheres because spherical metal powders are joined by metal bonds mainly in the vicinity of the contact points of the spheres and are not bonded to each other on the other surface. As a result, it is possible to secure a sufficient number of connected vacancies composed of open spaces. In addition, since spherical metal powders are three-dimensionally metal-bonded, it is excellent in uniform dispersibility of stress and high strength is obtained, and it is possible to exhibit excellent three-dimensional adhesion and reduce contact resistance. It has excellent effects such as.


Patent applicant Sanyo Special Steel Co., Ltd.
Attorney: Attorney Shiina

Claims (7)

When manufacturing a separator for a fuel cell, a metal powder-containing slurry or a metal powder-containing compound is laminated in a sheet form on a metal plate, and then the metal powders and metal powder and metal plate are sintered together. A manufacturing method comprising integrally forming a sheet-like porous body made of metal powder on a metal plate by metal bonding to each other. 2. The method for producing a fuel cell separator according to claim 1, wherein two or more slurries or compounds having different powder particle size ranges of the metal powder are laminated on a metal plate. 3. The method for producing a fuel cell separator according to claim 1, wherein a slurry containing a metal powder or a compound is laminated on both surfaces of the metal plate. A method for producing a separator for a fuel cell, wherein the powder according to any one of claims 1 to 3 is a spherical powder. A method for producing a fuel cell separator, wherein the metal powder according to any one of claims 1 to 4 is produced by an atomizing method. Regarding the porous body portion on the sintered metal plate obtained by the method according to any one of claims 1 to 5, the cross-sectional area of 0.1 mm ² in an arbitrary 1 mm ^{2 of the} sheet surface perpendicular to the thickness direction. A fuel cell separator characterized by having at least one hole having a diameter of 001 mm ² or more and penetrating the porous body portion in the thickness direction. The fuel cell separator obtained by the method according to any one of claims 1 to 5, in addition to the function of the separator and the separator flow path, the diffusion layer, the microporous layer, and one or two of them A fuel cell separator member having the plurality of functions described above.