WO2019106879A1 - Metallic porous body, fuel cell, and method for producing metallic porous body - Google Patents

Abstract

This disclosure provides a metallic porous body having a porous substrate and a heat resistant coating film, wherein the porous substrate has: a skeleton having a nickel alloy on the surface thereof; and continuous pores formed by the skeleton, the heat resistant coating film covering the surface of the skeleton, and the metallic porous body having a flat plate shape appearance.

Description

Porous metal body, fuel cell and method for producing porous metal body

The present disclosure relates to a porous metal body, a fuel cell, and a method of manufacturing the porous metal body. The present application claims priority based on Japanese Patent Application No. 2017-228595 filed on Nov. 29, 2017. The entire contents of the description of the Japanese patent application are incorporated herein by reference.

Among various fuel cells, a solid oxide fuel cell (SOFC, hereinafter also referred to as "SOFC") is a polymer electrolyte fuel cell (PEFC) or a phosphoric acid type. It is necessary to operate at a high temperature as compared to a fuel cell (Phosphoric Acid Fuel Cell; PAFC). However, SOFCs are actively being developed because they have advantages such as high power generation efficiency, no need for expensive catalysts such as platinum, and the ability to use waste heat.
The SOFC includes a solid electrolyte layer formed of a solid oxide, and an electrode layer formed on both sides of the solid electrolyte layer. In addition, a porous current collector is provided to collect and extract electrons generated at the electrode. The current collector often has a function as a gas diffusion layer in order to diffuse the gas supplied to the electrode and generate power efficiently.

Generally, a carbon structure or a stainless steel (SUS) structure is used for a gas diffusion layer of a fuel cell. Grooves to be gas flow paths are formed in the carbon structure and the SUS structure. The width of the groove is about 500 μm, and is in the form of a straight line. Since the grooves are provided in about 1/2 of the area of the surface where the carbon structure and the SUS structure are in contact with the electrolyte, the porosity of the gas diffusion layer is about 50%.
Since the gas diffusion layer as described above does not have a very high porosity and also has a large pressure loss, there is a problem in increasing the output while miniaturizing the fuel cell.

As a method of producing a metal porous body having a high porosity and a large surface area, a method of forming a metal layer on the surface of a resin molded article such as a foamed resin is known. For example, in Japanese Patent Application Laid-Open No. 11-154517 (Patent Document 1), the surface of the skeleton of a resin molded body is treated to be conductive, an electroplating layer made of metal is formed thereon, and the resin molded body is A method of producing a porous metal body by incineration and removal is described.

Japanese Patent Application Laid-Open No. 11-154517

The metal porous body according to one aspect of the present disclosure is
A flat metal porous body having continuous pores,
In the skeleton of the porous metal body, a heat resistant coating film is formed on the surface of a nickel alloy,
It is a metal porous body.
The method for producing a porous metal body according to one aspect of the present disclosure is
A method of producing a metal porous body according to one aspect of the present disclosure described above,
Preparing a flat porous substrate having continuous pores;
A heat-resistant coating film forming step of forming a heat-resistant coating film on the surface of the skeleton of the porous substrate,
Have
At least the surface of the skeleton of the porous substrate is formed of a nickel alloy,
It is a manufacturing method of a metal porous body.

In other words, the metal porous body according to another aspect of the present disclosure is
A metal porous body having a porous body substrate and a heat resistant coating film,
The porous substrate is
A framework having a nickel alloy on the surface,
And continuous pores formed by the above skeleton;
The heat resistant coating film covers the surface of the upper skeleton,
The porous metal body has a flat outer appearance,
It is a metal porous body.
Moreover, a method of producing a porous metal body according to another aspect of the present disclosure is
It is a method of manufacturing the above-mentioned porous metal body,
A preparation step of preparing a porous substrate having the skeleton and the continuous pores formed by the skeleton;
A heat-resistant coating film forming step of forming a heat-resistant coating film on the surface of the skeleton in the porous substrate,
Have
The porous base material has a flat appearance in appearance;
The skeleton in the porous substrate has a nickel alloy on its surface,
It is a manufacturing method of a metal porous body.

FIG. 1 is an enlarged photograph showing the structure of a skeleton of an example of a metal porous body having a skeleton of a three-dimensional network structure. FIG. 2 is an enlarged view schematically illustrating a partial cross section of an example of a metal porous body according to an embodiment of the present disclosure. FIG. 3 is a schematic view showing an example of a state in which areas A to E are defined on the metal porous body in the method of measuring the average film thickness of the heat resistant coating film in the metal porous body. FIG. 4 is a view schematically showing an image when a cross section (a cross section taken along line AA in FIG. 2) of the skeleton in the area A of the metal porous body shown in FIG. 3 is observed with a scanning electron microscope. FIG. 5 is a schematic view showing an example of the visual field (i) when the heat-resistant coating film 11 shown in FIG. 4 is enlarged and observed with a scanning electron microscope. FIG. 6 is a schematic view showing an example of a visual field (ii) when the heat-resistant coating film 11 shown in FIG. 4 is enlarged and observed with a scanning electron microscope. FIG. 7 is a schematic view showing an example of a visual field (iii) when the heat-resistant coating film 11 shown in FIG. 4 is enlarged and observed with a scanning electron microscope. FIG. 8 is a view schematically showing a partial cross section of an example of a porous substrate having a three-dimensional network skeleton. FIG. 9 is a view schematically showing a partial cross section of another example of a porous substrate having a three-dimensional network skeleton. FIG. 10 is a photograph of a foamed urethane resin as an example of a resin molded product having a skeleton of a three-dimensional network structure.

[Problems to be solved by the present disclosure]
The present inventors examined using a metal porous body having a high porosity in place of the carbon structure and the SUS structure as a current collector-gas diffusion layer of a fuel cell.
SOFC is a fuel cell operating at a high temperature of about 800.degree. In SOFC, hydrogen and carbon monoxide are supplied to the negative electrode (fuel electrode), and air (oxygen) is supplied to the positive electrode (air electrode). For this reason, when a metal porous body is used as the gas diffusion layer of the air electrode of SOFC, the metal porous body having stability over a long period of time under very severe conditions of a high temperature of about 800 ° C. and an oxidizing atmosphere. It is necessary to use the body.
Therefore, the present inventors have made a keen search to produce a porous metal body that can be used under high temperature oxidation conditions of about 800 ° C. First, focusing on nickel tungsten (NiW) and nickel molybdenum (NiMo) as alloys excellent in oxidation resistance, a metal porous body having a skeleton of nickel tungsten or nickel molybdenum was produced. Then, heat treatment was performed in the atmosphere at 800 ° C. for 500 hours.
As a result, even if the skeleton is a metal porous body consisting of nickel tungsten or nickel molybdenum, cracks or cracks may occur in part of the skeleton after heat treatment for a long time in a high temperature oxidizing atmosphere at about 800 ° C. It was found.

Therefore, in view of the above problems, the present disclosure has long-term stability even under high temperature oxidation conditions, and is a porous metal that can be suitably used as a current collector and gas diffusion layer for air electrodes of SOFCs. Intended to provide the body.

[Effect of the present disclosure]
According to the present disclosure, there is provided a metal porous body which has stability for a long time even under high temperature oxidation conditions and can be suitably used as a current collector and gas diffusion layer for air electrode of SOFC. be able to.

[Description of the embodiment of the present disclosure]
First, embodiments of the present disclosure will be listed and described.
(1) A porous metal body according to one aspect of the present disclosure is
A metal porous body having a porous body substrate and a heat resistant coating film,
The porous substrate is
A framework having a nickel alloy on the surface,
And continuous pores formed by the above skeleton;
The heat resistant coating film covers the surface of the upper skeleton,
The porous metal body has a flat outer appearance,
It is a metal porous body.
According to the aspect of the disclosure described in the above (1), it has stability over a long period of time even under high temperature oxidation conditions, and is preferably used also as a current collector and gas diffusion layer for the SOFC air electrode. A possible porous metal body can be provided.

(2) The porous metal body described in (1) above is
The heat resistant coating film preferably contains silver or cobalt.
According to the aspect of the disclosure described in the above (2), it is possible to provide a metal porous body excellent in conductivity even under high temperature oxidation conditions.

(3) The porous metal body according to (1) or (2) above is
The heat-resistant coating film preferably has an average film thickness of 1 μm or more.
According to the aspect of the disclosure described in the above (3), it is possible to provide a porous metal body that is more excellent in high-temperature oxidation resistance.

(4) The porous metal body according to any one of (1) to (3) above,
The nickel alloy preferably contains an alloy of nickel and at least one metal selected from the group consisting of tungsten, molybdenum, aluminum and titanium as a main component.
According to the aspect of the disclosure described in the above (4), it is possible to provide a metal porous body having high corrosion resistance and high strength.
In addition, the said main component shall mean the thing of the component with most ratio occupied in the said nickel alloy.

(5) The porous metal body according to any one of (1) to (4) above,
The shape of the skeleton is preferably a three-dimensional network structure.
(6) The porous metal body according to any one of (1) to (5) above,
The porosity is preferably 60% or more and 98% or less.
(7) The metal porous body according to any one of (1) to (6) above,
The average pore diameter is preferably 50 μm or more and 5000 μm or less.
According to the aspect of the disclosure described in any one of (5) to (7) above, a metal porous body that is lightweight and has a large surface area can be provided.

(8) The porous metal body according to any one of (1) to (7) above,
It is preferable that the thickness is 500 micrometers or more and 5000 micrometers or less.
According to the aspect of the disclosure described in (8) above, it is possible to provide a metal porous body that is lightweight and has high strength.
In addition, the thickness of said metal porous body shall mean the space | interval of the main surfaces of a flat metal porous body.

(9) A fuel cell according to one aspect of the present disclosure is
It is a fuel cell provided with the metal porous body as described in any one of said (1) to said (8) as a gas diffusion layer.
According to the aspect of the disclosure described in the above (9), it is possible to provide a small and lightweight fuel cell with high power generation efficiency.

(10) A method of producing a porous metal body according to one aspect of the present disclosure is
It is a manufacturing method of the metal porous body as described in any one of said (1) to said (8), Comprising:
A preparation step of preparing a porous substrate having the skeleton and the continuous pores formed by the skeleton;
A heat-resistant coating film forming step of forming a heat-resistant coating film on the surface of the skeleton in the porous substrate,
Have
The porous base material has a flat appearance in appearance;
The skeleton in the porous substrate has a nickel alloy on its surface,
It is a manufacturing method of a metal porous body.
(11) The method for producing a porous metal body according to (10) above,
The preparation step is performed by plating a nickel alloy on the surface of a resin molding having a skeleton and continuous pores formed by the skeleton,
It is preferable that the said resin molding has a flat-shaped external appearance.
According to the aspect of the disclosure described in the above (10) or (11), it is possible to provide a method for producing a metal porous body capable of producing the metal porous body described in the above (1).

(12) The method for producing a porous metal body according to (10) or (11) above,
The shape of the skeleton of the porous substrate is preferably a three-dimensional network structure.
According to the aspect of the disclosure described in the above (12), it is possible to provide a method for producing a metal porous body capable of producing the metal porous body described in the above (5).

[Details of the embodiment of the present disclosure]
Specific examples of the porous metal body, the fuel cell, and the method of manufacturing the porous metal body according to the embodiment of the present disclosure will be described in more detail below. The present invention is not limited to these exemplifications, is shown by the claims, and is intended to include all modifications within the scope and meaning equivalent to the claims.

<Porous metal body>
The metal porous body according to the embodiment of the present disclosure has continuous pores, and has a flat plate shape as a whole. In one aspect of the present embodiment, the metal porous body has a porous body substrate and a heat-resistant coating film. The porous substrate has a skeleton and continuous pores formed by the skeleton. Moreover, the said metal porous body has the shape where the external appearance is flat form. In the metal porous body, the continuous pores may be formed so as to penetrate at least main surfaces facing each other. In other words, the continuous pores may be formed so as to penetrate the opposing main surfaces in the shape of the metal porous body. From the viewpoint of increasing the surface area of the metal porous body, it is preferable that as many continuous pores as possible be formed. Examples of the shape of the skeleton of the porous metal body (shape of the skeleton of the porous substrate) include mesh-like shapes such as punching metal and expanded metal and shapes such as a three-dimensional network structure. Here, the “three-dimensional network structure” means a structure in which solid components (for example, metal, resin, etc.) constituting the film are three-dimensionally spread in a network shape. In addition, it is not necessary for the skeleton itself of the metal porous body (or the skeleton itself of the porous substrate to be described later) to have continuous pores. In other words, the skeleton itself need not be porous.

In the framework of the porous metal body, a heat resistant coating film is formed on the surface of a nickel alloy. That is, a nickel alloy is a base material, and a heat-resistant coating film is formed so as to cover the entire surface. In one aspect of the present embodiment, the porous substrate can be grasped as having a skeleton having a nickel alloy on the surface, and a heat-resistant coating film that covers the surface of the skeleton. In the case where the heat-resistant coating film is not formed on the surface of the skeleton of the porous metal body (the surface of the skeleton of the porous substrate) and the skeleton is formed of nickel tungsten or nickel molybdenum, the metal porous body is 800 When exposed to an oxidizing atmosphere for a long time at a high temperature of about ° C, cracks or cracks may occur in part of the skeleton, which may make it unsuitable for use depending on the use of the porous metal body. On the other hand, in the metal porous body according to the embodiment of the present disclosure, a heat resistant coating film is formed on the surface of a nickel alloy (skeleton of porous base material). Therefore, even if the metal porous body is exposed to an oxidizing atmosphere at a high temperature of about 800 ° C., it can be used stably for a long time without the occurrence of cracks or cracks in the skeleton. For this reason, the metal porous body according to the embodiment of the present disclosure can be suitably used, for example, even when used as a gas diffusion layer of an air electrode of SOFC without the strength of the skeleton being reduced. In addition, since the metal porous body has a large surface area, the fuel gas can be diffused more. Therefore, the said metal porous body can improve the contact opportunity of fuel gas and electrolyte, and can provide SOFC with high power generation efficiency.

The heat-resistant coating film may be, for example, a metal or alloy stable in a high temperature oxidizing atmosphere, such as silver (Ag), cobalt (Co), gold (Au), platinum (Pt) or the like. From the viewpoint of reducing the production cost of the porous metal body, the heat-resistant coating film is preferably silver or cobalt. In one aspect of the present embodiment, the heat-resistant coating film includes, for example, a metal or alloy stable in a high temperature oxidizing atmosphere, such as silver (Ag), cobalt (Co), gold (Au), platinum (Pt) or the like. And may contain silver or cobalt.
Silver and gold have very high conductivity, so the conductivity of the porous metal can be increased. In addition, cobalt becomes cobalt oxide on the surface due to the influence of oxygen. Cobalt oxide exhibits conductivity in a high temperature environment of about 800 ° C. For this reason, when the heat-resistant coating film is silver, gold or cobalt, the metal porous body according to the embodiment of the present disclosure is good not only as a gas diffusion layer but also as a current collector in a fuel cell.

The heat-resistant coating film preferably has an average film thickness of 1 μm or more. When the average film thickness of the heat-resistant coating film is 1 μm or more, the metal porous body can be stably maintained for a long time even under a high temperature oxidizing atmosphere of about 800 ° C. Heat resistant coatings are generally expensive. Therefore, from the viewpoint of suppressing the production cost of the porous metal body, the average film thickness of the heat-resistant coating film is preferably about 50 μm or less. From these viewpoints, the average film thickness of the heat-resistant coating film is more preferably 3 μm or more and 30 μm or less, and still more preferably 5 μm or more and 20 μm or less.

The nickel alloy may contain an alloy of nickel and a metal other than nickel as a main component, and a component other than an alloy of nickel and a metal other than nickel may be intentionally or unavoidably contained. In addition, a main component shall mean the thing of the component with most ratio occupied in the said nickel alloy. For example, the main component may be a component having a proportion of 50% or more in the nickel alloy.
The nickel alloy is at least one metal selected from the group consisting of nickel, tungsten, molybdenum, aluminum, and titanium from the viewpoint that the nickel alloy is relatively excellent in oxidation resistance and preferably high in strength. It is preferable to have an alloy of That is, the nickel alloy preferably contains nickel tungsten (NiW), nickel molybdenum (NiMo), nickel aluminum (NiAl) or nickel titanium (NiTi) as a main component.

As described above, the shape of the skeleton of the porous metal body (the shape of the skeleton of the porous substrate) may be a mesh shape, but is more preferably a three-dimensional network structure. When the shape of the skeleton is a three-dimensional network structure, the surface area can be larger than that of a skeleton such as punching metal or expanded metal. In addition, since the shape of the skeleton is more complicated, when used as a gas diffusion layer of a fuel cell, more gas can be diffused.

Hereinafter, the metal porous body according to the embodiment of the present disclosure will be described in more detail by taking a case where the shape of the skeleton of the metal porous body is a three-dimensional network structure as an example.
FIG. 1 shows an enlarged photograph of a skeleton of a three-dimensional network structure of an example of a metal porous body according to an embodiment of the present disclosure. Further, FIG. 2 shows an enlarged schematic view in which the cross section of the metal porous body shown in FIG. 1 is enlarged. In addition, FIG. 1 is an example of the metal porous body in which the plating film of silver was formed in the surface (surface of the skeleton of a porous-body base material) of silver as a heat-resistant coating film.
When the shape of the skeleton has a three-dimensional network structure, typically, as shown in FIG. 2, the interior 14 of the skeleton 13 of the porous metal body 10 is hollow. The surface of the skeleton 13 has a structure in which the heat-resistant coating film 11 is formed so as to cover the surface of the nickel alloy 12 which is the base material (porous body base material). The metal porous body 10 has continuous pores, and the skeleton 13 forms the pore portion 15.

Although the thickness of the heat-resistant coating film 11 is shown to be substantially the same as the thickness of the nickel alloy 12 in FIG. 2, the average film thickness of the heat-resistant coating film 11 is preferably 1 μm to 50 μm as described above. The thickness of the heat-resistant coating film 11 is usually thinner than that of the nickel alloy 12. The average film thickness of the heat-resistant coating film 11 refers to what is measured by observing the cross section of the skeleton 13 of the porous metal body 10 with an electron microscope as follows. An outline of a method of measuring the average film thickness of the heat-resistant coating film 11 is shown in FIGS.

First, for example, as shown in FIG. 3, the metal porous body 10 having a flat outer appearance is arbitrarily divided into areas, and five locations (area A to area E) are selected as measurement locations. Then, at each area, the skeleton 13 of the metal porous body 10 is arbitrarily selected at one place, and an AA line cross section shown in FIG. 2 of the skeleton is observed by a scanning electron microscope (SEM). The AA line cross section of the skeleton 13 of the metal porous body 10 has a substantially triangular shape as shown in FIG. In another aspect, the cross section AA of the skeleton of the metal porous body may be circular or square. In the example shown in FIG. 4, the interior 14 of the skeleton of the porous metal body 10 is hollow, and a film of the nickel alloy 12 is facing the hollow portion. The heat resistant coating film 11 is formed to cover the outer surface of the nickel alloy 12.

If it is possible to observe the entire cross section of the skeleton along the line AA by SEM, the magnification is further increased to confirm the entire thickness direction of the heat-resistant coating film 11 and to make the thickness direction appear larger in one view as much as possible. Set to Then, the maximum thickness and the minimum thickness of the heat-resistant coating film 11 are measured in three fields of view with respect to the AA line cross section of the same skeleton while changing the field of view. In all areas, the maximum thickness and the minimum thickness of the heat-resistant coating film 11 are measured in three fields of view on the AA line cross section of one arbitrary skeleton, and the average of them is the average film thickness of the heat-resistant coating film 11 It is said.

As an example, FIG. 5 shows a conceptual view of a visual field (i) when an AA line cross section of an arbitrary one skeleton in the area A of the metal porous body 10 shown in FIG. 3 is observed by SEM. Similarly, FIG. 6 shows a conceptual view of the visual field (ii) of the AA cross section of the same skeleton, and FIG. 7 shows a conceptual view of the visual field (iii).

The thickness of the heat-resistant coating film 11 is maximized in each of the visual field (i) to the visual field (iii) when the heat-resistant coating film 11 in an AA line cross section of any one frame in the area A is observed by SEM. Thickness (maximum thickness A (i), maximum thickness A (ii), maximum thickness A (iii)), and thickness at which the thickness of the heat-resistant coating film 11 becomes minimum (minimum thickness a (i), minimum thickness a (ii) , The minimum thickness a (iii)) is measured. The thickness of the heat resistant coating film 11 refers to the thickness of the heat resistant coating film 11 extending in the vertical direction from the surface of the nickel alloy 12.
When an alloy layer is formed between the heat-resistant coating film 11 and the nickel alloy 12, the thickness of the heat-resistant coating film 11 means the alloy layer and the heat-resistant coating which extend in the vertical direction from the surface of the nickel alloy 12. The total thickness of the film 11 is referred to.
Thereby, with respect to the cross section along the line AA of one arbitrary skeleton in the area A, the maximum thickness A (i) to the maximum thickness A (iii) of the three visual fields and the minimum thickness a (i) to the minimum thickness a ( iii) decide. The maximum thickness and the minimum thickness of the heat-resistant coating film 11 in three fields of view are also measured for the areas B, C, D, and E in the same manner as the area A, for the AA line cross section of any one frame.
The average of the maximum thickness A (i) to the maximum thickness E (iii) and the minimum thickness a (i) to the minimum thickness e (iii) of the heat-resistant coating film 11 measured as described above is It is called average film thickness.

The porous metal body according to the embodiment of the present disclosure preferably has a porosity of 60% or more and 98% or less. When the porosity of the porous metal body is 60% or more, the porous metal body can be made very lightweight, and furthermore, when the porous metal body is used as a gas diffusion layer of a fuel cell, gas diffusion can be achieved. Can be enhanced. In addition, when the porosity of the metal porous body is 98% or less, the metal porous body can have sufficient strength. From these viewpoints, the porosity of the metal porous body is more preferably 70% or more and 98% or less, and still more preferably 80% or more and 98% or less.
The porosity of the porous metal body is defined by the following equation.
Porosity = (1-(mass of porous material [g] / (apparent volume of porous material [cm ³ ] x material density [g / cm ³ ])) x 100 [%]

The average pore diameter of the porous metal body is preferably 50 μm or more and 1000 μm or less. When the average pore diameter is 50 μm or more, the strength of the metal porous body can be enhanced, and further, when the metal porous body is used as a gas diffusion layer of a fuel cell, the gas diffusivity can be enhanced. The bendability of a metal porous body can be improved because an average pore diameter is 1000 micrometers or less. From these viewpoints, the average pore diameter of the metal porous body is more preferably 100 μm or more and 500 μm or less, and still more preferably 150 μm or more and 400 μm or less.
With the average pore diameter of the porous metal body, the surface of the porous metal body is observed with a microscope or the like, and the number of pores per inch (25.4 mm) is counted as the number of cells, and the average pore diameter = 25.4 mm / cell number It shall mean what is calculated as

The porous metal body having a flat plate shape preferably has a thickness of 500 μm or more and 5000 μm or less. When the thickness of the metal porous body is 500 μm or more, the metal porous body can have sufficient strength and can have high gas diffusion performance when used as a gas diffusion layer of a fuel cell. When the thickness of the metal porous body is 5000 μm or less, a lightweight metal porous body can be obtained. From these viewpoints, the thickness of the porous metal body is more preferably 600 μm or more and 2000 μm or less, and still more preferably 700 μm or more and 1500 μm or less.

<Fuel cell>
The fuel cell according to the embodiment of the present disclosure may be provided with the metal porous body according to the above-described embodiment of the present disclosure as a gas diffusion layer, and other configurations adopt the same configuration as the conventional fuel cell. Can. As the other configuration, for example, a solid electrolyte layer, an electrode layer stacked on both sides sandwiching the solid electrolyte layer, an interconnector subjected to simple gas flow path processing for making gas diffusion more uniform. Etc. In addition, the metal porous body concerning embodiment of this indication can be made to act not only as a gas diffusion layer but as a collector.
The type of fuel cell is not limited, and may be a solid oxide fuel cell (SOFC), a polymer electrolyte fuel cell (PEFC) or a phosphoric acid fuel cell (PAFC).
In general, a solid oxide fuel cell operates at a high temperature of about 800 ° C., and an air electrode is supplied with air containing oxygen. For this reason, the metal porous body disposed as the gas diffusion layer on the air electrode side needs to be able to stably exist even in a high temperature oxidizing atmosphere under very severe conditions.
Since the heat resistant coating film is formed on the surface of the skeleton (the surface of the skeleton of the porous substrate), the metal porous body according to the embodiment of the present disclosure is stable for a long time even in a high temperature oxidizing atmosphere at about 800 ° C. Can exist. In addition, since the porous metal body according to the embodiment of the present disclosure has a high porosity, when used as a gas diffusion layer, the gas can be efficiently diffused. Furthermore, since the metal porous body according to the embodiment of the present disclosure has high conductivity, it can exhibit high function as a current collector. Therefore, a fuel cell using the porous metal body according to the embodiment of the present disclosure as a gas diffusion layer and a current collector has high power generation efficiency.

<Method of producing porous metal body>
The method for producing a porous metal body according to an embodiment of the present disclosure is a method for producing the above-mentioned porous metal body, and a preparation step of preparing a flat porous substrate having continuous pores; And a heat-resistant coating film forming step of forming a heat-resistant coating film on the surface of the skeleton of the material. In another aspect, the method for producing a porous metal body includes a preparing step of preparing a porous substrate having the skeleton and the continuous pores formed by the skeleton, and the skeleton in the porous substrate. Forming a heat-resistant coating film on the surface of the heat-resistant coating film, and the porous substrate has a flat appearance in appearance, and the skeleton of the porous substrate is It has a nickel alloy on the surface.
Each step is described in detail below.

(Preparation process)
The preparation step is a step of preparing a porous substrate having continuous pores and having a flat plate shape as a whole. In another aspect, the porous base material can be grasped as having the skeleton and the continuous pores formed by the skeleton. The porous substrate is the substrate (porous substrate) in the metal porous body according to the embodiment of the present disclosure, that is, the nickel alloy 12. For this reason, the porous substrate prepared in this step may have a skeleton of a mesh shape such as punching metal or expanded metal, but is more preferably a shape of a three-dimensional network structure.
The porous base may be at least the surface of the skeleton formed of a nickel alloy. The skeleton of the porous substrate may have a hollow structure inside or a structure in which a nickel alloy is formed on the surface of a resin molded body.

The nickel alloy may be the same as the nickel alloy in the metal porous body according to the embodiment of the present disclosure described above. That is, the nickel alloy may contain an alloy of nickel and a metal other than nickel as a main component, and a component other than an alloy of nickel and a metal other than nickel may be intentionally or unavoidably contained. The nickel alloy is preferably an alloy of nickel and any one or more metals selected from the group consisting of tungsten, molybdenum, aluminum and titanium.

FIG. 8 shows an enlarged schematic view of an enlarged cross section of an example of a porous base having a skeleton of a three-dimensional network structure. As shown in FIG. 8, the skeleton 83 of the porous substrate 80 is formed of a nickel alloy 82. The porous substrate 80 has a skeleton of a three-dimensional network structure, and the interior 84 of the skeleton 83 is hollow. In addition, the porous base material 80 has continuous pores, and the pore portion 85 is formed by the skeleton 83.
FIG. 9 shows an enlarged schematic view in which a cross section of another example of a porous base having a skeleton of a three-dimensional network structure is enlarged. As shown in FIG. 9, the skeleton 93 of the porous substrate 90 has a structure in which a nickel alloy 92 is formed so as to cover the surface of the skeleton of the resin molded body 96 having a skeleton of a three-dimensional network structure. The porous substrate 90 has continuous pores, and the skeleton 93 forms the pores 95.

Since the metal porous body according to the embodiment of the present disclosure is formed by forming the heat resistant coating film on the surface of the skeleton of the porous body base, the porosity and the average pore diameter of the metal porous body are each a porous body And the average pore diameter of the For this reason, the porosity and the average pore diameter of the porous substrate may be appropriately selected in accordance with the porosity and the average pore diameter of the porous metal body to be produced. The porosity and the average pore size of the porous substrate are defined in the same manner as the porosity and the average pore size of the porous metal body according to the embodiment of the present disclosure described above.

If the desired porous substrate can not be obtained from the market, it may be produced by the following method.
First, a sheet-like (flat plate-like) resin molded body (hereinafter, also simply referred to as a “resin molded body”) having a skeleton of a three-dimensional network structure is prepared. A polyurethane resin, a melamine resin, etc. can be used as a resin molding. The photograph of the foaming urethane resin which has frame | skeleton of a three-dimensional network structure in FIG. 10 is shown.
Subsequently, a conductive treatment step of forming a conductive layer on the surface of the skeleton of the resin molded body is performed. The conductive treatment may be, for example, applying a conductive paint containing conductive particles such as carbon and conductive ceramic, forming a layer of a conductive metal such as nickel and copper by electroless plating, or depositing Alternatively, this can be performed by forming a layer of a conductive metal such as aluminum by sputtering.

Then, a nickel alloy is plated using the resin molding which formed the conductive layer in the surface of frame | skeleton as a base material. The plating of the nickel alloy may be performed by a known method.
Nickel tungsten, for example, using a plating bath of 0.15 mol / L of nickel sulfate, 0.15 mol / L of sodium tungstate, and 0.3 mol / L of triammonium ammonium, pH 7, bath temperature 40 ° C., current It can be plated at a density of 5 A / dm ² . The current density is based on the apparent area of the substrate.
In addition, nickel molybdenum has a pH 7 and a bath temperature of 40 ° C., for example, using a plating bath containing 0.15 mol / L of nickel sulfate, 0.15 mol / L of sodium molybdate, and 0.3 mol / L of triammonium ammonium citrate. , Plating at a current density of 5 A / dm ² . The current density is based on the apparent area of the substrate. Here, "apparent area of the substrate" means, for example, the area of the main surface of the substrate having a flat plate shape.

By forming a plating film of a nickel alloy on the surface of the skeleton of the resin molded body as described above, a porous substrate 90 shown in FIG. 9 is obtained. In addition, after a plated film of a nickel alloy is formed on the surface of the skeleton of the resin molded body, the porous resin base 80 shown in FIG. 8 can be obtained by removing the resin molded body by heat treatment or the like.
The porosity and the average pore diameter of the porous substrate are substantially equal to the porosity and the average pore diameter of the resin molded product used as the substrate. For this reason, the porosity and the average pore diameter of the resin molded product may be appropriately selected in accordance with the porosity and the average pore diameter of the porous substrate, which is the production object. The porosity and the average pore size of the resin molded body are defined in the same manner as the porosity and the average pore size of the porous metal body described above.

As another method of forming a plating film of a nickel alloy on the surface of a resin molded body having a conductive layer formed on the surface of a skeleton, first, a nickel plating film is formed, and then a plating film of a metal other than nickel is formed. There is also a method of alloying.
For example, in the case of forming a plating film of nickel aluminum or nickel titanium as a nickel alloy, first, a nickel plating film is formed on the surface of the skeleton of the resin molded body, and then an aluminum plating film or a titanium plating film is formed. Good. When a high temperature molten salt bath is used in plating aluminum or titanium, the aluminum or titanium is plated at the same time as alloying with nickel proceeds, and the resin molding also disappears. In the case of using a low temperature molten salt bath when plating aluminum, heat treatment may be performed after the formation of the aluminum plating film to effect alloying of nickel and aluminum and removal of the resin molded body.

The formation of the nickel plating film may use either electroless nickel plating or electrolytic nickel plating, but electrolytic plating is preferable because it is more efficient. In the case of performing electrolytic nickel plating, it may be performed according to a conventional method. As a plating bath used for an electrolytic nickel plating process, a well-known or commercially available thing can be used, for example, a watt bath, a chlorination bath, a sulfamic acid bath etc. are mentioned.
A conductive resin layer having a conductive layer formed on the surface of the skeleton is immersed in the plating bath, the conductive resin layer is connected to the cathode and the nickel counter electrode plate is connected to the anode, and a direct current or pulse intermittent current is applied to the conductive layer. A nickel plating film can be formed on the surface of

The aluminum plating can be performed by electrolysis (molten salt electrolysis) in a molten salt bath so that the resin molded body after the formation of the nickel plating film acts as a cathode.
As the molten salt, for example, it is possible to use an electrolytic solution in which an aluminum halide is added to a halide-based molten salt. As the halide based molten salt, for example, a chloride based molten salt or a fluoride based molten salt can be used. As the chloride-based molten salt, for example, KCl, NaCl, CaCl ₂ , LiCl, RbCl, CsCl, SrCl ₂ , BaCl ₂ , MgCl ₂ or their eutectic salts can be used. As the fluoride-based molten salt, for example, LiF, NaF, KF, RbF, CsF, MgF ₂ , CaF ₂ , SrF ₂ , BaF ₂ or a eutectic salt thereof can be used. Among the above-mentioned halides, it is preferable to use a chloride-based molten salt from the viewpoint of efficiency, and it is preferable to use KCl, NaCl and CaCl ₂ from the viewpoint of being inexpensive and easy to obtain.
Also, by using an organic molten salt which is a eutectic salt of an organic halide and an aluminum halide, a plated film of aluminum can be formed at a low temperature. Examples of the organic halide include 1-ethyl-3-methylimidazolium chloride (EMIC) and butyl pyridinium chloride (BPC). The aluminum halides may include, for example, aluminum chloride (AlCl _3).
When aluminum is plated using an organic molten salt, for example, the resin molded body can be formed while alloying nickel and aluminum by heating to about 600 ° C. or higher in an oxidizing atmosphere such as the air. It can be incinerated and removed.

The plating of titanium contains a metal ion of a Group 1 metal, a fluoride ion, and a titanium ion. For example, titanium is further dissolved in a molten salt bath of at least one of lithium fluoride (LiF) and sodium fluoride (NaF) and at least one of lithium chloride (LiCl) and sodium chloride (NaCl); It can carry out by carrying out molten salt electrolysis using the metal porous body which has nickel as a main component as a cathode in the molten salt bath which melt | dissolved.
The titanium ion may be Ti ⁴⁺ or Ti ³⁺ .

It is necessary to add titanium to the above molten salt bath to cause a leveling reaction of 3Ti ⁴ + + Ti metal → 4Ti ³ + in the molten salt bath. The amount of titanium added to the molten salt bath may be an amount exceeding the minimum amount necessary for Ti ⁴⁺ in the molten salt bath to become Ti ³⁺ . By sufficiently dissolving titanium in the molten salt bath in advance, titanium to be electrodeposited can be prevented from dissolving in the molten salt bath at the time of subsequent molten salt electrolysis.

(Heat resistant coating film forming process)
The heat resistant coating film forming step is a step of forming a heat resistant coating film on the surface of the skeleton of the porous substrate prepared in the preparation step. In another aspect, the heat-resistant coating film forming step can be grasped as a step of forming a heat-resistant coating film on the surface of the porous substrate prepared in the preparation step. Although the method of forming a heat-resistant coating film is not limited, it is preferable to form by plating from a viewpoint of forming efficiently.
The heat-resistant coating film may be any metal or alloy stable in a high temperature oxidizing atmosphere, such as silver (Ag), cobalt (Co), gold (Au), platinum (Pt) or the like. From the viewpoint of the production cost of the porous metal body, the heat-resistant coating film is preferably silver or cobalt. In another aspect, the heat-resistant coating film preferably contains silver or cobalt.

-Silver plating-
The silver plating method is not particularly limited, and can be performed by a known method. For example, it is preferred to carry out by electroplating in a silver methanesulfonate plating bath. Moreover, it is preferable to perform silver strike plating before silver plating.

-Cobalt plating-
The method of plating cobalt is not particularly limited, but, for example, it is preferable to carry out by the following method. That is, an aqueous solution having a composition of 350 g / L of cobalt sulfate, 45 g / L of cobalt chloride, 25 g / L of sodium chloride and 35 g / L of boric acid is prepared as a cobalt plating solution, and the current density is 2 A at room temperature (about 20 ° C.). By setting it as / dm < ² >, cobalt can be plated on the surface of the skeleton of the porous substrate.

<Method for Producing Hydrogen, and Device for Producing Hydrogen>
The porous metal body according to the embodiment of the present disclosure can be suitably used, for example, as a gas diffusion layer for a fuel cell or an electrode for hydrogen production by water electrolysis. Hydrogen production methods are roughly classified into [1] alkaline water electrolysis method, [2] PEM (Polymer Electrolyte Membrance) method, and [3] SOEC (Solid Oxide Electrolysis Cell) method. A porous body can be used.

In the alkaline water electrolysis system of said [1], an anode and a cathode are immersed in strong alkaline aqueous solution, and it is the system which electrolyzes water by applying a voltage. By using a metal porous body as an electrode, the contact area of water and an electrode becomes large, and the efficiency of electrolysis of water can be raised.
In the method for producing hydrogen by the alkaline water electrolysis method, the metal porous body has an average pore diameter of 100 μm when viewed from above (for example, when viewed from the main surface side when the appearance of the metal porous body is flat). The thickness is preferably 5000 μm or less. When the average pore diameter when the porous metal body is viewed from above is 100 μm or more, the generated hydrogen or oxygen bubbles are clogged in the pores of the porous metal body, and the contact area between water and the electrode decreases. It can be suppressed. In addition, when the average pore diameter when the metal porous body is viewed from above is 5000 μm or less, the surface area of the electrode becomes sufficiently large, and the efficiency of water electrolysis can be enhanced. From the same viewpoint, the average pore diameter of the metal porous body as viewed from above is more preferably 400 μm or more and 4000 μm or less.
The thickness of the metal porous body and the weight per area of the metal may cause deflection or the like if the electrode area becomes large, and may be appropriately selected according to the scale of equipment. The weight of the metal is preferably 200 g / m ² or more and 2000 g / m ² or less, more preferably 300 g / m ² or more and 1200 g / m ² or less, and more preferably 400 g / m ² or more and 1000 g It is further preferable that the ratio is about / m ² or less. In order to achieve both of bubble removal and securing of the surface area, a plurality of metal porous bodies having different average pore sizes can be used in combination.

The PEM method of the above [2] is a method of electrolyzing water using a solid polymer electrolyte membrane. An anode and a cathode are disposed on both sides of a solid polymer electrolyte membrane, and a voltage is applied while flowing water on the anode side, whereby hydrogen ions generated by the electrolysis of water are made to the cathode side through the solid polymer electrolyte membrane. It is a system which is moved and taken out as hydrogen on the cathode side. The operating temperature is about 100 ° C. A polymer electrolyte fuel cell that generates electric power by hydrogen and oxygen and discharges water is the same as that of the solid polymer fuel cell, and the operation is completely reversed. Since the anode side and the cathode side are completely separated, there is an advantage that high purity hydrogen can be taken out. Since the anode and the cathode need to be permeating the electrode to pass water and hydrogen gas, the electrode needs a conductive porous body.

Since the metal porous body according to the embodiment of the present disclosure has high porosity and good electrical conductivity, it can be used for PEM type water electrolysis as well as it can be suitably used for a polymer electrolyte fuel cell. It can be used suitably. In the method for producing hydrogen by the PEM method, the porous metal body preferably has an average pore diameter of 150 μm or more and 1000 μm or less when viewed from above. When the average pore diameter is 150 μm or more when the metal porous body is viewed from above, generated hydrogen and oxygen bubbles are clogged in the pores of the metal porous body, and the contact area between water and the solid polymer electrolyte membrane is It can suppress becoming small. In addition, since the average pore diameter when the metal porous body is viewed from the top is 1000 μm or less, sufficient water retention can be secured, and water can be prevented from passing through before reacting, which is efficient. Water electrolysis can be performed. From the same viewpoint, the average pore diameter when the metal porous body is viewed from above is more preferably 200 μm or more and 700 μm or less, and still more preferably 300 μm or more and 600 μm or less.

The thickness of the metal porous body and the weight of the metal may be appropriately selected according to the scale of equipment, but if the porosity is too small, the pressure loss for passing water will be large, so the porosity is 30% or more It is preferable to adjust the thickness and the weight of the metal so that In addition, in the PEM method, the conduction between the solid polymer electrolyte membrane and the electrode is crimped, so the amount of attached metal is adjusted so that the increase in electrical resistance due to deformation and creep at the time of pressure is within a practically acceptable range. There is a need. The weight of the metal is preferably 200 g / m ² or more and 2000 g / m ² or less, more preferably 300 g / m ² or more and 1200 g / m ² or less, and more preferably 400 g / m ² or more and 1000 g It is further preferable that the ratio is about / m ² or less. In addition, in order to achieve both porosity and electrical connection, it is also possible to use a plurality of metal porous bodies having different average pore sizes in combination.

The SOEC method of the above [3] is a method of electrolyzing water using a solid oxide electrolyte membrane, and the configuration differs depending on whether the electrolyte membrane is a proton conductive membrane or an oxygen ion conductive membrane. In the oxygen ion conductive film, hydrogen is generated on the cathode side supplying water vapor, so the hydrogen purity is lowered. Therefore, from the viewpoint of hydrogen production, it is preferable to use a proton conductive membrane.
An anode and a cathode are disposed on both sides of the proton conductive membrane, and a voltage is applied while introducing water vapor on the anode side, whereby hydrogen ions generated by the electrolysis of water are moved to the cathode side through the solid oxide electrolyte membrane , And only hydrogen is taken out on the cathode side. The operating temperature is about 600 ° C. or more and 800 ° C. or less. A solid oxide fuel cell that generates electricity with hydrogen and oxygen and discharges the water, and operates in the completely opposite manner with the same configuration.

Both the anode and the cathode need to be permeable to the electrode and pass water vapor and hydrogen gas, so the electrode needs a porous body which is electrically conductive and, in particular, resistant to a high temperature oxidizing atmosphere on the anode side. Since the porous metal body according to the embodiment of the present disclosure has high porosity, good electrical conductivity, high oxidation resistance and heat resistance, it is the same as it can be suitably used for solid oxide fuel cells. In addition, it can be suitably used for SOEC type water electrolysis.

In the method of producing hydrogen according to the SOEC system, the porous metal body preferably has an average pore diameter of 150 μm or more and 1000 μm or less when viewed from above. When the average pore diameter when the porous metal body is viewed from above is 150 μm or more, water vapor and generated hydrogen are clogged in the pores of the porous metal body, and the contact area between the water vapor and the solid oxide electrolyte membrane becomes small. Can be suppressed. In addition, when the metal porous body is viewed from the top, when the average pore diameter is 1000 μm or less, it is possible to suppress that the pressure loss becomes too low and the water vapor passes through before sufficiently reacting. From the same viewpoint, the average pore diameter when the metal porous body is viewed from above is more preferably 200 μm or more and 700 μm or less, and still more preferably 300 μm or more and 600 μm or less.

The thickness of the metal porous body and the weight of the metal may be appropriately selected depending on the scale of the equipment, but if the porosity is too small, the pressure loss for introducing water vapor becomes large, so the porosity is 30% or more It is preferable to adjust the thickness and the weight of the metal so that Further, in the SOEC method, since the conduction between the solid oxide electrolyte membrane and the electrode is crimped, it is necessary to adjust the metal basis weight so that the increase in the electrical resistance due to deformation and creep at the time of pressure is practically acceptable. There is. The weight of the metal is preferably 200 g / m ² or more and 2000 g / m ² or less, more preferably 300 g / m ² or more and 1200 g / m ² or less, and more preferably 400 g / m ² or more and 1000 g It is further preferable that the ratio is about / m ² or less. In addition, in order to achieve both porosity and electrical connection, it is also possible to use a plurality of metal porous bodies having different average pore sizes in combination.

<Supplementary Note>
The above description includes the features described below.
(Supplementary Note 1)
A method of generating hydrogen by electrolyzing water using a porous metal body as an electrode,
The metal porous body is a flat metal porous body having continuous pores,
In the skeleton of the porous metal body, a heat resistant coating film is formed on the surface of a nickel alloy,
Hydrogen production method.
(Supplementary Note 2)
The method for producing hydrogen according to claim 1, wherein the heat-resistant coating film is silver or cobalt.
(Supplementary Note 3)
The method for producing hydrogen according to Appendix 1 or 2, wherein the heat-resistant coating film has an average film thickness of 1 μm or more.
(Supplementary Note 4)
The hydrogen according to any one of Appendixes 1 to 3, wherein the nickel alloy contains an alloy of nickel and at least one selected from the group consisting of tungsten, molybdenum, aluminum, and titanium as a main component. Manufacturing method.
(Supplementary Note 5)
15. The method for producing hydrogen according to any one of Appendices 1 to 4, wherein the shape of the skeleton is a three-dimensional network structure.
(Supplementary Note 6)
15. The method for producing hydrogen according to any one of appendices 1 to 5, wherein the porous metal body has a porosity of 60% or more and 98% or less.
(Appendix 7)
15. The method for producing hydrogen according to any one of Appendices 1 to 6, wherein the porous metal body has an average pore diameter of 50 μm or more and 5000 μm or less.
(Supplementary Note 8)
15. The method for producing hydrogen according to any one of appendices 1 to 7, wherein the metal porous body has a thickness of 500 μm or more and 5000 μm or less.
(Appendix 9)
The method for producing hydrogen according to any one of appendices 1 to 8, wherein the water is a strong alkaline aqueous solution.
(Supplementary Note 10)
The metal porous body is disposed on both sides of a solid polymer electrolyte membrane, and the solid polymer electrolyte membrane and the metal porous body are brought into contact with each other, and each metal porous body acts as an anode and a cathode. 15. The method for producing hydrogen according to any one of appendices 1 to 8, wherein hydrogen is generated on the cathode side by supplying and electrolyzing the hydrogen.
(Supplementary Note 11)
The metal porous body is disposed on both sides of a solid oxide electrolyte membrane, and the solid oxide electrolyte membrane and the metal porous body are brought into contact with each other, and each metal porous body acts as an anode and a cathode. 15. The method for producing hydrogen according to any one of appendices 1 to 8, wherein hydrogen is generated on the cathode side by supplying water to electrolyze water.

(Supplementary Note 12)
An apparatus for producing hydrogen capable of generating hydrogen by electrolyzing water,
Comprising a flat metal porous body provided with continuous pores as an electrode;
In the skeleton of the porous metal body, a heat resistant coating film is formed on the surface of a nickel alloy,
Hydrogen production equipment.
(Supplementary Note 13)
The apparatus for producing hydrogen according to claim 12, wherein the heat-resistant coating film is silver or cobalt.
(Supplementary Note 14)
The apparatus for producing hydrogen according to Appendix 12 or 13, wherein the heat-resistant coating film has an average film thickness of 1 μm or more.
(Supplementary Note 15)
The hydrogen according to any one of Appendices 12 to 14, wherein the nickel alloy contains, as a main component, an alloy of nickel and at least one selected from the group consisting of tungsten, molybdenum, aluminum, and titanium. Production equipment.
(Supplementary Note 16)
15. The hydrogen production apparatus according to any one of appendices 12 to 15, wherein the shape of the skeleton is a three-dimensional network structure.
(Supplementary Note 17)
15. The apparatus for producing hydrogen according to any one of appendixes 12 to 16, wherein the porous metal body has a porosity of 60% to 98%.
(Appendix 18)
15. The apparatus for producing hydrogen according to any one of appendixes 12 to 17, wherein the porous metal body has an average pore diameter of 50 μm or more and 5000 μm or less.
(Appendix 19)
15. The apparatus for producing hydrogen according to any one of appendixes 12 to 18, wherein the porous metal body has a thickness of 500 μm or more and 5000 μm or less.
(Supplementary Note 20)
15. The apparatus for producing hydrogen according to any one of appendices 12 to 19, wherein the water is a strong alkaline aqueous solution.
(Supplementary Note 21)
Having an anode and a cathode on both sides of the solid polymer electrolyte membrane,
The anode and the cathode are in contact with the solid polymer electrolyte membrane,
An apparatus for producing hydrogen capable of generating hydrogen on the cathode side by electrolyzing water supplied to the anode side, wherein
15. The apparatus for producing hydrogen according to any one of appendixes 12 to 19, wherein the metal porous body is used for at least one of the anode and the cathode.
(Supplementary Note 22)
Having an anode and a cathode on both sides of the solid oxide electrolyte membrane,
The anode and the cathode are in contact with the solid oxide electrolyte membrane,
An apparatus for producing hydrogen capable of generating hydrogen on the cathode side by electrolyzing water vapor supplied to the anode side, wherein
15. The apparatus for producing hydrogen according to any one of appendixes 12 to 19, wherein the metal porous body is used for at least one of the anode and the cathode.

(Supplementary Note 101)
A flat metal porous body having continuous pores,
In the skeleton of the porous metal body, a heat resistant coating film is formed on the surface of a nickel alloy,
Porous metal body.
(Supplementary Note 102)
The metal porous body according to appendix 101, wherein the heat-resistant coating film is silver or cobalt.
(Supplementary Note 103)
The metal porous body according to Appendix 101 or 102, wherein the heat-resistant coating film has an average film thickness of 1 μm or more.
(Supplementary Note 104)
The metal according to any one of Appendices 101 to 103, wherein the nickel alloy contains, as a main component, an alloy of nickel and at least one selected from the group consisting of tungsten, molybdenum, aluminum, and titanium. Porous body.
(Supplementary Note 105)
Supplementary note 101 to Supplementary note 104, wherein the shape of the skeleton is a three-dimensional network structure.
(Supplementary Note 106)
The metal porous body according to any one of appendixes 101 to 105, wherein the porosity of the metal porous body is 60% or more and 98% or less.
(Supplementary Note 107)
The metal porous body according to any one of Appendixes 101 to 106, wherein the porous metal body has an average pore diameter of 50 μm or more and 5000 μm or less.
(Supplementary Note 108)
The metal porous body according to any one of appendixes 101 to 107, wherein the thickness of the porous metal body is 500 μm or more and 5000 μm or less.
(Supplementary Note 109)
A fuel cell comprising the metal porous body according to any one of appendixes 101 to 108 as a gas diffusion layer.
(Supplementary Note 110)
A method for producing the porous metal body according to appendix 101, wherein
Preparing a flat porous substrate having continuous pores;
A heat-resistant coating film forming step of forming a heat-resistant coating film on the surface of the skeleton of the porous substrate,
Have
At least the surface of the skeleton of the porous substrate is formed of a nickel alloy,
Method of manufacturing porous metal body.
(Supplementary Note 111)
The preparation step is carried out by plating a nickel alloy on the surface of the skeleton of a flat resin molding having continuous pores.
The manufacturing method of the metal porous body as described in appendix 110.
(Supplementary Note 112)
The method for producing a metal porous body according to Appendix 110 or 111, wherein the shape of the skeleton of the porous base material is a three-dimensional network structure.

Hereinafter, the present invention will be described in more detail based on examples, but these examples are illustrative, and the porous metal body and the like of the present invention are not limited to these. The scope of the present invention is shown by the statement of a claim, and the meaning of a statement and an equivalent within a statement of a claim and all the changes within the limits are included.

Example 1
-Preparation process-
First, as a resin molding having a skeleton of a three-dimensional network structure, foamed urethane having a thickness of 1.2 mm and a size of a main surface of 15 cm × 15 cm was prepared. The porosity of the foamed urethane was 95%, and the average pore diameter was 440 μm.
A conductive layer was formed on the surface of the skeleton by subjecting the foamed urethane to a conductive treatment. The conductive treatment was performed by applying and drying a solvent in which carbon was dispersed.
A nickel tungsten plating film was formed on the surface of the urethane foam skeleton using the urethane foam after the conductive treatment as a substrate. Nickel tungsten plating is performed using a plating bath containing 0.15 mol / L of nickel sulfate, 0.15 mol / L of sodium tungstate, and 0.3 mol / L of triammonium ammonium, pH 7, bath temperature 40 ° C., current It was performed under the conditions of a density 5A / dm ^2. The current density is based on the apparent area of the substrate.
As a result, porous substrate No. 1 in which the surface of the skeleton is made of nickel tungsten. 1 was obtained.
-Heat-resistant coating film formation process-
The porous body substrate No. A silver plating film was formed on the surface of the framework 1 as a heat-resistant coating film, and the resin molding (foamed urethane) was removed by heat treatment.
Silver plating uses a silver plating solution having a composition of 2 g / L of silver cyanide and 100 g / L of sodium cyanide, the temperature of the plating solution is 25 ° C., the current density is 2 A / dm ^2, and the stainless steel plate is an anode. Was conducted by energizing for 20 minutes. The current density is based on the apparent area of the porous substrate.
As a result, a porous metal body No. 1 in which a silver plating film is formed on the surface of nickel tungsten is obtained. 1 was obtained.

(Example 2)
-Preparation process-
In the same manner as in Example 1, porous base material No. 1 was prepared.
-Heat-resistant coating film formation process-
The porous body substrate No. A plated film of cobalt was formed as a heat-resistant coating film on the surface of the framework 1 and heat treatment was further performed to remove the resin molded product (urethane foam).
For cobalt plating, prepare a cobalt plating solution with a composition of 350 g / L of cobalt sulfate, 45 g / L of cobalt chloride, 25 g / L of sodium chloride and 35 g / L of boric acid, and use 2A current density at room temperature (about 20 ° C). / was carried out by a dm ^2. The current density is based on the apparent area of the porous substrate.
As a result, a porous metal body No. 1 in which a plated film of cobalt is formed on the surface of nickel tungsten. 2 was obtained.

(Example 3)
-Preparation process-
First, as a resin molding having a skeleton of a three-dimensional network structure, foamed urethane having a thickness of 1.2 mm and a size of a main surface of 15 cm × 15 cm was prepared. The porosity of the foamed urethane was 95%, and the average pore diameter was 440 μm.
A conductive layer was formed on the surface of the skeleton by subjecting the foamed urethane to a conductive treatment. The conductive treatment was performed by applying and drying a solvent in which carbon was dispersed.
A nickel molybdenum plated film was formed on the surface of the urethane foam skeleton using the urethane foam after the conductive treatment as a substrate. Plating of nickel-molybdenum is performed using a plating bath containing 0.15 mol / L of nickel sulfate, 0.15 mol / L of sodium molybdate, and 0.3 mol / L of triammonium ammonium, pH 7, bath temperature 40 ° C., current It was performed under the conditions of a density 5A / dm ^2. The current density is based on the apparent area of the substrate.
As a result, porous substrate No. 1 in which the surface of the skeleton is made of nickel molybdenum. 2 was obtained.
-Heat-resistant coating film formation process-
The porous body substrate No. A silver plating film was formed on the surface of the framework 2 as a heat-resistant coating film, and the resin molding (foamed urethane) was removed by heat treatment.
The formation of the silver plating film and the heat treatment were performed in the same manner as in Example 1.
Thereby, a metal porous body No. 1 in which a silver plating film was formed on the surface of nickel molybdenum. 3 was obtained.

(Example 4)
-Preparation process-
In the same manner as in Example 3, porous base material No. 2 was prepared.
-Heat-resistant coating film formation process-
The porous body substrate No. A cobalt plated film was formed on the surface of the framework 2 as a heat-resistant coating film, and the resin molded product (urethane foam) was removed by heat treatment.
The formation of the cobalt plating film and the heat treatment were performed in the same manner as in Example 3.
As a result, a porous metal body No. 1 in which a plating film of cobalt is formed on the surface of nickel molybdenum. 4 was obtained.

-Evaluation-
Metallic porous body No. 1 produced in the examples. 1 to No. The high temperature oxidation resistance and resistance of No. 4 were evaluated as follows. As a reference, porous base material No. 1 and No. 1 The high temperature oxidation resistance and the resistance were similarly evaluated for 2 as well.

(appearance)
Metallic porous body No. 1 to No. The porosity of 4 was 94%, and the average pore diameter was 430 μm.
In addition, porous metal body No. 1 to No. The cross section of the skeleton of No. 4 was observed by SEM, and the average film thickness of the heat-resistant coating film was measured as described above. As a result, porous metal body No. The average film thickness of the heat resistant coating film of No. 1 is 20 μm. No. 2 is 10 μm, and metal porous body No. No. 3 is 20 μm. 4 was 10 μm.

(High temperature oxidation resistance)
Metallic porous body No. 1 to No. 4 and porous substrate No. 4 1, No. 2 was heat-treated at 800 ° C. for 500 hours under the atmosphere.
No. Metal porous body No. 2 after heat treatment. 1 to No. 4 and porous substrate No. 4 1, No. The skeleton of 2 was observed visually.
As a result, porous substrate No. 1 in which the heat resistant coating film was not formed on the surface of the skeleton 1 and No. 1 In 2), cracks and cracks occurred in part of the skeleton, making it brittle. On the other hand, porous metal body No. 1 to No. No. 4 had no abnormality in the skeleton even after heat treatment, and maintained sufficient strength.

(Resistance measurement)
As in the case of strength measurement, porous metal body No. 1 1 to No. 4 and porous substrate No. 4 1, No. 2 was heat treated.
No. Metal porous body No. 2 after heat treatment. 1 to No. 4 and porous substrate No. 4 1, No. The electrical resistance of 2 was measured.
In the measurement of the electrical resistance, the size of the test piece was 4 cm × 4 cm, and the electrical resistance in the thickness direction was measured at 800 ° C. by the four-terminal method. The results are shown in Table 1.

From Table 1, porous metal body No. 1 to No. 4 is a porous substrate No. 4; 1 and No. 1 Compared to 2, it showed extremely low resistance even at high temperature of 800 ° C., and it was shown that it can be suitably used also as a collector of SOFC.

DESCRIPTION OF SYMBOLS 10 metal porous body, 11 heat resistant coating film, 12 nickel alloy, 13 frame, 14 frame inside, 15 pores, 80 porous substrate, 82 nickel alloy, 83 frame, 84 frame inside, 85 pores, 90 pores Body base material, 92 nickel alloy, 93 skeleton, 95 pores, 96 resin moldings.

Claims (12)

1. A metal porous body having a porous body substrate and a heat resistant coating film,
   The porous substrate is
   A framework having a nickel alloy on the surface,
   And continuous pores formed by the skeleton;
   The heat-resistant coating film covers the surface of the skeleton,
   The porous metal body has a flat shape in appearance.
   Porous metal body.
2. The metal porous body according to claim 1, wherein the heat-resistant coating film contains silver or cobalt.
3. The metal porous body according to claim 1 or 2, wherein the heat-resistant coating film has an average film thickness of 1 μm or more.
4. 4. The nickel alloy according to any one of claims 1 to 3, wherein an alloy of nickel and at least one metal selected from the group consisting of tungsten, molybdenum, aluminum and titanium is used as a main component. Metal porous body as described.
5. The metal porous body according to any one of claims 1 to 4, wherein the shape of the skeleton is a three-dimensional network structure.
6. The metal porous body according to any one of claims 1 to 5, wherein the porosity of the metal porous body is 60% or more and 98% or less.
7. The metal porous body according to any one of claims 1 to 6, wherein the metal porous body has an average pore diameter of 50 μm or more and 1000 μm or less.
8. The metal porous body according to any one of claims 1 to 7, wherein the thickness of the metal porous body is 500 μm or more and 5000 μm or less.
9. A fuel cell comprising the porous metal body according to any one of claims 1 to 8 as a gas diffusion layer.
10. A method of producing a metal porous body according to any one of claims 1 to 8, which is:
    Providing a porous substrate having the skeleton and the continuous pores formed by the skeleton;
    A heat-resistant coating film forming step of forming a heat-resistant coating film on the surface of the skeleton in the porous substrate;
    Have
    The porous substrate has a flat appearance in appearance;
    The skeleton in the porous substrate has a nickel alloy on its surface,
    Method of manufacturing porous metal body.
11. The preparation step is performed by plating a nickel alloy on the surface of a resin molding having a skeleton and continuous pores formed by the skeleton,
    The resin molded body has a flat shape in appearance.
    The manufacturing method of the metal porous body of Claim 10.
12. The method for producing a metal porous body according to claim 10 or 11, wherein a shape of a skeleton of the porous body base is a three-dimensional network structure.

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