JP2019215987A - Alloy member, cell stack, and cell stack device - Google Patents

Abstract

To provide an alloy member, a cell stack, and a cell stack device, capable of suppressing a coating film from being peeled off.SOLUTION: A top board 201 includes: a substrate 210 composed of an alloy material containing chromium; a chromium oxide film 211 covering a surface 210a of the substrate 210; and a coating film 212 covering a surface 211a of the chromium oxide film 211. The substrate 210 has a plurality of recesses 210b respectively formed on the surface 210a. The chromium oxide film 211 has a plurality of buried parts 211b respectively buried at the inside of the recesses 210b. Each of the buried parts 211b is constricted at an opening S2 of each of the recesses 210b. The buried parts 211b have an average depth of 0.7 μm or more in a cross section of the substrate 210.SELECTED DRAWING: Figure 7

Description

  The present invention relates to an alloy member, a cell stack, and a cell stack device.

  2. Description of the Related Art Conventionally, a cell stack device including a cell stack in which a plurality of fuel cells, which are a kind of electrochemical cells, are electrically connected by a current collecting member, and a manifold that supports each fuel cell is known ( Patent Documents 1 and 2). An alloy member is used for the current collecting member and the manifold.

  In the current collecting member of Patent Literature 1, chromium oxide formed on the surface of a base material is used to suppress volatilization of Cr from a base material formed of an Fe-Cr-based alloy, a Ni-Cr-based alloy, or the like. A coating is provided to cover the membrane.

International Publication No. 2013/172451

  However, in the current collecting member of Patent Literature 1, since the thermal expansion coefficients of the base material and the coating film are different, the coating film may peel off together with the chromium oxide film.

  The present invention has been made in view of the above situation, and an object of the present invention is to provide an alloy member, a cell stack, and a cell stack device that can suppress peeling of a coating film.

  The alloy member according to the present invention includes a base made of an alloy material containing chromium, a chromium oxide film covering at least a part of the surface of the base, and a coating covering at least a part of the surface of the chromium oxide film. And a membrane. The substrate has a plurality of recesses formed on the surface. The chromium oxide film has a plurality of embedded portions embedded inside each of the plurality of concave portions. Each of the plurality of buried portions is constricted by an opening of each of the plurality of recesses. In the cross section of the base material, the average depth of the plurality of buried portions is 0.7 μm or more.

  ADVANTAGE OF THE INVENTION According to this invention, the alloy member which can suppress peeling of a coating film, a cell stack, and a cell stack apparatus can be provided.

Perspective view of a cell stack device Perspective view of manifold Cross section of cell stack device Perspective view of a fuel cell QQ sectional view of FIG. PP sectional view of FIG. Enlarged view of region A in FIG. Explanatory drawing of the manufacturing method of the manifold Explanatory drawing of the manufacturing method of the manifold Explanatory drawing of the manufacturing method of the manifold Explanatory drawing of the manufacturing method of the manifold Sectional view showing another configuration of the concave portion

[Cell Stack Device 100]
FIG. 1 is a perspective view of the cell stack device 100. The cell stack device 100 includes a manifold 200 and a cell stack 250.

[Manifold 200]
FIG. 2 is a perspective view of the manifold 200. The manifold 200 is an example of an “alloy member”.

  The manifold 200 is configured to distribute a fuel gas (for example, hydrogen or the like) to each fuel cell 300. The manifold 200 is hollow and has an internal space. Fuel gas is supplied to the internal space of the manifold 200 via the introduction pipe 204.

  The manifold 200 has a top plate 201 and a container 202. The top plate 201 is formed in a flat plate shape. The container 202 is formed in a cup shape. The top plate 201 is arranged so as to close the upper opening of the container 202.

The top plate 201 is joined to the container 202 by a joining material 103 (not shown in FIG. 2, see FIG. 6). Examples of the bonding material 103 include crystallized glass, amorphous glass, brazing material, and ceramics. In the present embodiment, the term “crystallized glass” means that the ratio of the “volume occupied by the crystal phase” to the total volume (crystallinity) is 60% or more, and the “volume occupied by the amorphous phase and impurities” to the total volume. The glass has a ratio of less than 40%. Examples of such crystallized glass include, for example, SiO ₂ —B ₂ O ₃ , SiO ₂ —CaO, and SiO ₂ —MgO.

  A plurality of insertion holes 203 are formed in the top plate 201. The insertion holes 203 are arranged in the direction in which the fuel cells 300 are arranged (the z-axis direction). Each insertion hole 203 is arranged with an interval therebetween. Each insertion hole 203 communicates with the inside space of the manifold 200 and the outside.

  The detailed configuration of the manifold 200 will be described later.

[Cell Stack 250]
FIG. 3 is a cross-sectional view of the cell stack device 100. The cell stack 250 has a plurality of fuel cells 300 and a plurality of current collecting members 301.

  Each fuel cell 300 extends from the manifold 200. Specifically, each fuel cell 300 extends upward (x-axis direction) from the top plate 201 of the manifold 200. That is, the longitudinal direction (x-axis direction) of each fuel cell 300 extends upward. The length of each fuel cell 300 in the longitudinal direction (x-axis direction) can be about 100 to 300 mm, but is not limited thereto.

  The base end of each fuel cell 300 is inserted into the insertion hole 203 of the manifold 200. Each fuel cell 300 is fixed to the insertion hole 203 by the bonding material 101. The fuel cell 300 is fixed to the manifold 200 by the bonding material 101 while being inserted into the insertion hole 203. The bonding material 101 is filled in a gap between the fuel cell 300 and the insertion hole 203. Examples of the bonding material 101 include crystallized glass, amorphous glass, brazing material, and ceramics.

  Each fuel cell 300 is formed in a plate shape extending in the longitudinal direction (x-axis direction) and the width direction (y-axis direction). The fuel cells 300 are arranged at intervals in the arrangement direction (z-axis direction). The interval between two adjacent fuel cells 300 is not particularly limited, but may be about 1 to 5 mm.

  Each fuel cell 300 has a gas channel 11 inside. During operation of the cell stack device 100, a fuel gas (such as hydrogen) is supplied from the manifold 200 to each gas channel 11, and an oxidizing gas (such as air) is supplied to the outer periphery of each fuel cell 300.

Two adjacent fuel cells 300 are electrically connected by a current collecting member 301. The current collecting member 301 is joined to the base end side of each of two adjacent fuel cells 300 via the joining material 102. The bonding material 102 is, for example, at least one selected from (Mn, Co) ₃ O ₄ , (La, Sr) MnO ₃ , and (La, Sr) (Co, Fe) O ₃ .

[Fuel cell 300]
FIG. 4 is a perspective view of the fuel cell 300. FIG. 5 is a sectional view taken along line QQ of FIG.

  The fuel cell 300 has a support substrate 10 and a plurality of power generation element units 20.

(Support substrate 10)
The support substrate 10 has a plurality of gas passages 11 extending in the longitudinal direction (x-axis direction) of the support substrate 10 therein. Each gas flow path 11 extends from the base end side of the support substrate 10 toward the tip end side. Each gas passage 11 extends substantially parallel to each other.

  As shown in FIG. 5, the support substrate 10 has a plurality of first concave portions 12. In the present embodiment, each of the first concave portions 12 is formed on both main surfaces of the support substrate 10, but may be formed on only one main surface. The first recesses 12 are arranged at intervals in the longitudinal direction of the support substrate 10.

The support substrate 10 is made of a porous material having no electron conductivity. The support substrate 10 can be made of, for example, CSZ (calcia-stabilized zirconia). Alternatively, the support substrate 10 may be composed of NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia), or composed of NiO (nickel oxide) and Y ₂ O ₃ (yttria). Alternatively, it may be composed of MgO (magnesium oxide) and MgAl ₂ O ₄ (magnesia alumina spinel). The porosity of the support substrate 10 is, for example, about 20 to 60%.

(Power generation element section 20)
Each power generation element unit 20 is supported by the support substrate 10. In the present embodiment, each power generation element unit 20 is formed on both main surfaces of the support substrate 10, but may be formed only on one main surface. The power generating elements 20 are arranged at intervals in the longitudinal direction of the support substrate 10. That is, the fuel cell 300 according to the present embodiment is a so-called horizontal stripe fuel cell. The power generating elements 20 adjacent in the longitudinal direction are electrically connected to each other by an interconnector 31.

  The power generation element unit 20 has a fuel electrode 4, an electrolyte 5, an air electrode 6, and a reaction prevention film 7.

  The fuel electrode 4 is a fired body made of a porous material having electron conductivity. The anode 4 has an anode current collector 41 and an anode active section 42.

  The anode current collector 41 is disposed in the first recess 12. Specifically, the anode current collector 41 is filled in the first recess 12 and has the same outer shape as the first recess 12. The fuel electrode current collector 41 has a second recess 411 and a third recess 412. The fuel electrode active part 42 is arranged in the second recess 411. Further, the interconnector 31 is arranged in the third recess 412.

  The fuel electrode current collector 41 has electron conductivity. The anode current collector 41 preferably has higher electron conductivity than the anode active part 42. The fuel electrode current collector 41 may or may not have oxygen ion conductivity.

The fuel electrode current collector 41 may be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Alternatively, the anode current collector 41 may be composed of NiO (nickel oxide) and Y ₂ O ₃ (yttria), or may be composed of NiO (nickel oxide) and CSZ (calcia-stabilized zirconia). Is also good. The thickness of the anode current collector 41 and the depth of the first recess 12 are about 50 to 500 μm.

  The fuel electrode active part 42 has oxygen ion conductivity and electron conductivity. The anode active part 42 has a higher content of a substance having oxygen ion conductivity than the anode current collector 41. More specifically, the volume ratio of the substance having oxygen ion conductivity to the entire volume excluding the pore portion in the anode active portion 42 is determined by the ratio of the oxygen ion conductivity to the entire volume excluding the pore portion in the anode current collector 41. It is larger than the volume ratio of the substance having the property.

  The fuel electrode active portion 42 can be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Alternatively, the fuel electrode active portion 42 may be composed of NiO (nickel oxide) and GDC (gadolinium-doped ceria). The thickness of the fuel electrode active part 42 is 5 to 30 μm.

  The electrolyte 5 is disposed so as to cover the fuel electrode 4. Specifically, the electrolyte 5 extends in a longitudinal direction from one interconnector 31 to an adjacent interconnector 31. That is, in the longitudinal direction (x-axis direction) of the support substrate 10, the electrolytes 5 and the interconnectors 31 are arranged alternately and continuously. The electrolyte 5 is configured to cover both main surfaces of the support substrate 10.

  The electrolyte 5 is a fired body made of a dense material having ion conductivity and no electron conductivity. The electrolyte 5 can be composed of, for example, YSZ (8YSZ) (yttria-stabilized zirconia). Alternatively, the electrolyte 5 may be composed of LSGM (lanthanum gallate). The thickness of the electrolyte 5 is, for example, about 3 to 50 μm.

  The air electrode 6 is a fired body made of a porous material having electron conductivity. The air electrode 6 is disposed on the side opposite to the fuel electrode 4 with respect to the electrolyte 5. The air electrode 6 has an air electrode active part 61 and an air electrode current collecting part 62.

  The cathode active part 61 is disposed on the reaction prevention film 7. The air electrode active portion 61 has oxygen ion conductivity and electron conductivity. The cathode active portion 61 has a higher content of a substance having oxygen ion conductivity than the cathode current collector 62. More specifically, the volume ratio of the substance having oxygen ion conductivity to the total volume excluding the pore portion in the cathode active portion 61 is determined by the oxygen ion conductivity in the cathode current collecting portion 62 relative to the entire volume excluding the pore portion. It is larger than the volume ratio of the substance having the property.

The cathode active portion 61 can be composed of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, the air electrode active portion 61 is configured such that LSF = (La, Sr) FeO ₃ (lanthanum strontium ferrite), LNF = La (Ni, Fe) O ₃ (lanthanum nickel ferrite), or LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite) or the like. The air electrode active portion 61 may be configured by two layers of a first layer (inner layer) made of LSCF and a second layer (outer layer) made of LSC. The thickness of the air electrode active part 61 is, for example, 10 to 100 μm.

  The air electrode current collector 62 is arranged on the air electrode active unit 61. Further, the air electrode current collector 62 extends from the air electrode active part 61 toward an adjacent power generation element part. The fuel electrode current collector 41 and the air electrode current collector 62 extend from the power generation region to opposite sides. The power generation region is a region where the fuel electrode active portion 42, the electrolyte 5, and the air electrode active portion 61 overlap.

  The air electrode current collector 62 is a fired body made of a porous material having electron conductivity. The cathode current collector 62 preferably has higher electron conductivity than the cathode active unit 61. The air electrode current collector 62 may or may not have oxygen ion conductivity.

The air electrode current collector 62 can be composed of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, the air electrode current collector 62 may be made of LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite). Alternatively, the air electrode current collector 62 may be made of Ag (silver) or Ag-Pd (silver-palladium alloy). The thickness of the air electrode current collector 62 is, for example, about 50 to 500 μm.

  The reaction prevention film 7 is a fired body made of a dense material. The reaction prevention film 7 is disposed between the electrolyte 5 and the cathode active portion 61. The reaction prevention film 7 suppresses the occurrence of a phenomenon in which YSZ in the electrolyte 5 reacts with Sr in the air electrode 6 to form a reaction layer having a large electric resistance at the interface between the electrolyte 5 and the air electrode 6. It is provided in.

The reaction prevention film 7 is made of a material containing ceria containing a rare earth element. The reaction prevention film 7 can be made of, for example, GDC = (Ce, Gd) O ₂ (gadolinium-doped ceria). The thickness of the reaction prevention film 7 is, for example, about 3 to 50 μm.

  The interconnector 31 is configured to electrically connect the power generating element units 20 adjacent in the longitudinal direction (x-axis direction) of the support substrate 10. Specifically, the air electrode current collector 62 of one of the power generating elements 20 extends toward the other power generating element 20. Further, the fuel electrode current collector 41 of the other power generation element section 20 extends toward the one power generation element section 20. The interconnector 31 electrically connects the air electrode current collector 62 of the one power generation element unit 20 and the fuel electrode current collector 41 of the other power generation element unit 20. The interconnector 31 is arranged in the third recess 412 of the anode current collector 41. Specifically, the interconnector 31 is embedded in the third recess 412.

The interconnector 31 is a fired body made of a dense material having electron conductivity. The interconnector 31 can be made of, for example, LaCrO ₃ (lanthanum chromite). Alternatively, the interconnector 31 may be composed of (Sr, La) TiO ₃ (strontium titanate). The thickness of the interconnector 31 is, for example, 10 to 100 μm.

[Detailed Configuration of Manifold 200]
Next, a detailed configuration of the manifold 200 will be described with reference to the drawings. FIG. 6 is a sectional view taken along the line PP of FIG. FIG. 7 is an enlarged view of a region A in FIG. FIG. 7 corresponds to a cross section perpendicular to a surface 210a of the base 210 described later.

  As shown in FIG. 6, the top plate 201 and the container 202 are joined by the joining material 103. An internal space S1 to which fuel gas is supplied is formed between the top plate 201 and the container 202.

  The top plate 201 has a base 210, a chromium oxide film 211, and a coating film 212. The container 202 has a base material 220, a chromium oxide film 221, and a coating film 222.

  The top plate 201 and the container 202 are each an example of an “alloy member”. The base material 210 and the base material 220 are each examples of a “base material”. Each of the chromium oxide films 211 and 221 is an example of a “chromium oxide film”. Each of the coating film 212 and the coating film 222 is an example of a “coating film”.

  Since the configuration of the container 202 is the same as the configuration of the top plate 201, the configuration of the top plate 201 will be described below with reference to FIG.

  The base 210 is formed in a plate shape. The substrate 210 may be flat or curved. The thickness of the substrate 210 is not particularly limited, but may be, for example, 0.1 to 2.0 mm.

  The base 210 is made of an alloy material containing Cr (chromium). As such a metal material, an Fe-Cr alloy steel (such as stainless steel) or a Ni-Cr alloy steel can be used. The content of Cr in the substrate 210 is not particularly limited, but may be 4 to 30% by mass.

The substrate 210 may contain Ti (titanium) or Al (aluminum). The content of Ti in the substrate 210 is not particularly limited, but may be 0.01 to 1.0 at. %. The content of Al in the substrate 210 is not particularly limited, but may be 0.01 to 0.4 at. %. The base material 210 may contain Ti as TiO ₂ (titania), or may contain Al as Al ₂ O ₃ (alumina).

  As shown in FIG. 7, the base 210 has a surface 210a and a plurality of recesses 210b. The surface 210a is an outer surface of the base 210. The substrate 210 is bonded to the chromium oxide film 211 on the surface 210a. In FIG. 7, the surface 210a is formed in a substantially planar shape, but may have irregularities, or may be entirely or partially curved or bent.

  Each recess 210b is formed on the surface 210a. Each recess 210b extends from the opening S2 formed in the surface 210a toward the inside of the base 210. Each buried portion 211b of the chromium oxide film 211 described later is buried in each concave portion 210b.

  Each recess 210b narrows as it approaches the opening S2. That is, in a cross section perpendicular to the surface 210a of the base 210, the width of each recess 210b is narrow near the opening S2. The width W1 of the opening S2 is the length of a straight line CL connecting the edge of the opening S2 at the shortest distance in the cross section. The width W1 of the opening S2 is not particularly limited, but may be, for example, 0.3 to 30 μm. In consideration of giving sufficient strength to each buried portion 211b described later, the width W1 is preferably 0.5 μm or more.

  Note that the shape of the concave portion 210b is not particularly limited as long as the width of the concave portion 210b is reduced near the opening S2.

  The chromium oxide film 211 is formed on the surface of the base 210. The chromium oxide film 211 may cover substantially the entire surface of the substrate 210, or may cover at least a part of the surface of the substrate 210. The chromium oxide film 211 contains chromium oxide as a main component.

  As shown in FIG. 7, the chromium oxide film 211 has a surface 211a and a plurality of buried portions 211b. The surface 211a is an outer surface of the chromium oxide film 211. The chromium oxide film 211 is bonded to the coating film 212 on the surface 211a.

  Each buried portion 211b is arranged in each concave portion 210b of the base 210. Each buried portion 211b may be filled in the entire concave portion 210b, or may be arranged in a part of each concave portion 210b.

  Each buried portion 211b is narrowed at the opening S2 of each concave portion 210b. That is, each embedded portion 211b is locally thin near the opening S2. With such a bottleneck structure, each buried portion 211b is locked by each concave portion 210b, and an anchor effect is generated.

  In the present embodiment, “the embedded portion 211b is constricted at the opening S2” means that the width W2 of the embedded portion 211b is larger than the width W1 of the opening S2 in a cross section perpendicular to the surface 210a of the base 210. I do. The width W2 of the buried portion 211b is the maximum dimension of the buried portion 211b in a direction parallel to the straight line CL that defines the width W1 of the opening S2.

  Here, the “average depth” of the plurality of embedded portions 211b is 0.7 μm or more. Accordingly, a sufficient anchoring effect can be exerted as a whole of the plurality of buried portions 211b, so that the adhesion of the chromium oxide film 211 to the base 210 can be improved. As a result, peeling of the coating film 212 from the base 210 together with the chromium oxide film 211 can be suppressed.

  The “average depth” of the plurality of embedded portions 211b refers to the depth of each of the ten embedded portions 211b randomly selected from an image magnified 1000 to 20000 times by FE-SEM (field emission scanning electron microscope). It is a value obtained by arithmetically averaging D1. The depth D1 of the buried portion 211b is the maximum dimension of the buried portion 211b in a direction perpendicular to the straight line CL that defines the width W1 of the opening S2. However, since the embedded portion 211b having a depth D1 of less than 0.1 μm has a small anchor effect and little contribution to the effect of suppressing the peeling of the coating film 212, when calculating the average depth of the multiple embedded portions 211b. Shall be excluded.

  The average depth of the plurality of embedded portions 211b is preferably 1.0 μm or more, and more preferably 1.5 μm or more. The average depth of the plurality of buried portions 211b is preferably 30 μm or less.

  The depth D1 of each embedded portion 211b is not particularly limited, but may be, for example, 0.5 to 30 μm. The standard deviation of the depth D1 of each of the ten buried portions 211b used for calculating the average depth is preferably 0.2 or more. Thereby, the anchor effect of the plurality of embedded portions 211b as a whole can be further improved. The ratio of the standard deviation of the depth D1 to the average depth (so-called variation coefficient) is not particularly limited, but may be, for example, 0.1 to 0.95, and is preferably 0.2 or more and 0.9 or less.

  In the ten buried portions 211b used for calculating the average depth, the difference between the maximum value and the minimum value of the depth D1 is not particularly limited, but can be, for example, 0.5 to 29 μm, and 1 to 25 μm. preferable.

  The “average width” of the plurality of embedded portions 211b is not particularly limited, but may be, for example, 0.5 to 35 μm. The “average width” of the plurality of embedded portions 211b is a value obtained by arithmetically averaging the width W2 of each of the ten embedded portions 211b used for calculating the average depth.

  In consideration of further improving the anchor effect of the plurality of embedded portions 211b as a whole, the average width of the plurality of embedded portions 211b is preferably 0.5 μm or more, and more preferably 0.7 μm or more.

  The width W2 of each embedded portion 211b is not particularly limited, but may be, for example, 0.5 to 35 μm. In consideration of further improving the anchor effect of each buried portion 211b, the width W2 of the buried portion 211b is preferably 101% or more of the width W1 of the opening S2, more preferably 105% or more, and particularly preferably 110% or more.

  The standard deviation of the width W2 of each of the ten embedded portions 211b used for calculating the average width is preferably 0.2 or more. Thereby, the anchor effect of the plurality of embedded portions 211b as a whole can be further improved. The ratio of the standard deviation of the width W2 to the average width (so-called variation coefficient) is not particularly limited, but may be, for example, 0.1 to 0.95, and is preferably 0.2 or more and 0.9 or less.

  In the ten embedded portions 211b used for calculating the average width, the difference between the maximum value and the minimum value of the width W2 is not particularly limited, but may be, for example, 0.5 to 34 μm, and preferably 1 to 30 μm.

  In a cross section perpendicular to the surface 210a of the base 210, the “existence number” of the buried portions 211b in a plane direction parallel to the surface 210a is preferably 3/10 mm or more. Thus, the stress applied to the chromium oxide film 211 can be dispersed, so that occurrence of minor defects in the chromium oxide film 211 and the coating film 212 can be suppressed.

  The “presence number” of the embedded portions 211b in the plane direction is the number of the embedded portions 211b provided per unit length of the surface 210a in a cross section perpendicular to the surface 210a of the base 210. The number of buried portions 211b is a value obtained by dividing the total number of buried portions 211b by the total length (total length) of the surface 210a on the FE-SEM image described above. When counting the number of embedded portions 211b, the number of embedded portions 211b that are only partially reflected in the FE-SEM image is counted as one. However, since the embedded portion 211b having a depth D1 of less than 0.5 μm has a small contribution to the stress dispersion effect, it is excluded when calculating the number of the embedded portions 211b.

  The number of the buried portions 211b in the plane direction is more preferably 100 / mm or less. This can prevent the concave portions 210b from being connected to each other, so that the shape of each concave portion 210b can be maintained for a long period of time.

  The “average equivalent circle diameter” of the plurality of buried portions 211b is not particularly limited, but may be 0.5 to 35 μm. The “average equivalent circle diameter” of the plurality of embedded portions 211b is a value obtained by arithmetically averaging the “equivalent circle diameters” of each of the ten embedded portions 211b used for calculating the average depth. The “equivalent circle diameter” is the diameter of a circle having the same area as the buried portion 211b on the FE-SEM image described above. When determining the area of the embedded portion 211b, the base end of the embedded portion 211b is defined by a straight line CL that defines the width W1 of the opening S2.

  The coating film 212 covers at least a part of the surface 211a of the chromium oxide film 211. Specifically, the coating film 212 covers at least a part of a region of the surface 211a of the chromium oxide film 211 that comes into contact with the oxidizing gas during operation of the cell stack device 100. It is preferable that the coating film 212 covers the entire surface of the region of the chromium oxide film 211 that comes into contact with the oxidizing gas. The thickness of the coating film 212 is not particularly limited, but may be, for example, 1 to 200 μm.

  The coating film 212 suppresses the volatilization of Cr from the surface of the substrate 210. Accordingly, it is possible to suppress the electrode (the air electrode 6 in the present embodiment) of each fuel cell 300 from being deteriorated due to the poisoning of Cr.

  The coating film 212 is a ceramic material, and a suitable material can be appropriately selected depending on an application location. Examples of the ceramic material applied to the coating film of the current collecting member requiring conductivity include spinel composed of a perovskite-type composite oxide containing La and Sr and a transition metal such as Mn, Co, Ni, Fe, and Cu. Type composite oxide. On the other hand, as a ceramic material applied to a coating film of a fuel manifold requiring insulation, alumina, silica, zirconia, crystallized glass, and the like can be given. However, the coating film 212 is only required to suppress the volatilization of Cr, and the constituent material of the coating film 212 is not limited to the above ceramic material.

[Manufacturing method of manifold 200]
A method for manufacturing the manifold 200 will be described with reference to the drawings. Since the method of manufacturing the container 202 is the same as the method of manufacturing the top plate 201, the method of manufacturing the top plate 201 will be described below.

  First, as shown in FIG. 8, a plurality of recesses 210b are formed on the surface 210a of the base 210. For example, by using shot peening, sand blast, or wet blast, the concave portion 210b having a predetermined shape can be efficiently formed. At this time, by adjusting the depth and width of each recess 210b, the average depth, the standard deviation of the depth D1, and the maximum and minimum values of the depth D1 of the plurality of buried portions 211b formed in a later process are adjusted. Difference, average width, average circle equivalent diameter, etc. can be controlled. Further, by adjusting the number of the recesses 210b in the plane direction, the number of the buried parts 211b in the plane direction can be controlled.

  Next, as shown in FIG. 9, by rolling a roller on the surface 210 a of the base 210, the opening S <b> 2 of the concave portion 210 c is flattened while the opening S <b> 2 is narrowed. At this time, the width W1 of the opening S2 can be adjusted by adjusting the pressing force of the roller.

  Next, as shown in FIG. 10, after applying a chromium oxide paste on the surface 210 a of the base 210 and filling the recesses 210 c with the chromium oxide paste, the base 210 is heat-treated in an air atmosphere (800 to 900). C. for 5 to 20 hours) to form a chromium oxide film 211 on the surface 210a of the base 210 and in each of the recesses 210b. Thereby, a buried portion 211b buried in each recess 210c is formed.

  Next, as shown in FIG. 11, a coating material 212 is formed by applying a ceramic material paste on the chromium oxide film 211 and performing a heat treatment (800 to 900 ° C., 1 to 5 hours).

(Other embodiments)
The present invention is not limited to the above embodiment, and various modifications or changes can be made without departing from the scope of the present invention.

[Modification 1]
In the above embodiment, the alloy member according to the present invention is applied to the manifold 200, but the invention is not limited to this. The alloy member according to the present invention can be used as a member constituting a part of the cell stack device 100 and the cell stack 250. For example, the alloy member according to the present invention can be suitably used for the current collecting member 301 electrically connected to the fuel cell 300.

[Modification 2]
In the above embodiment, the cell stack 250 has a horizontal stripe fuel cell, but may have a so-called vertical stripe fuel cell. The vertical stripe type fuel cell includes a conductive support substrate, a power generation unit (a fuel electrode, a solid electrolyte layer, and an air electrode) disposed on one main surface of the support substrate, and disposed on another main surface of the support substrate. And an interconnector.

[Modification 3]
In the above embodiment, the concave portion 210b of the base 210 is formed directly on the surface 210a. However, as shown in FIG. 12, the concave portion 210b may be formed inside the annular convex portion 210c formed on the surface 210a. Good. Such an annular convex portion 210c can be formed by weakening the pressing force of the roller shown in FIG. Thus, even when the concave portion 210b is formed inside the annular convex portion 210c, it is possible to suppress the coating film 212 from peeling off from the base 210 together with the chromium oxide film 211.

[Modification 4]
In the above embodiment, the case where the alloy member according to the present invention is applied to a cell stack of a fuel cell, which is an example of an electrochemical cell, has been described. The present invention is applicable to a cell stack of an electrochemical cell including the cell.

  Hereinafter, examples of the present invention will be described. However, the present invention is not limited to the examples described below.

(Examples 1 to 14 and Comparative Examples 1 to 3)
The alloy members according to Examples 1 to 14 and Comparative Examples 1 to 3 were produced as follows.

  First, a base material of 20 mm × 40 mm × 0.5 mm was prepared for each sample by punching out an alloy member (SUS430, SUS445J1, or SUS316) shown in Table 1.

  Next, a plurality of recesses were formed on the surface of the substrate by shot peening. At this time, by adjusting the depth of each recess, the average depth, the standard deviation of the depth, and the difference between the maximum value and the minimum value of the depth for each sample are adjusted for each sample. Changed to

  Next, the width of the opening of each recess was reduced by rolling a roller on the surface of the substrate.

  Next, a chromium oxide paste is applied to the surface of the base material, and the recess is filled with the chromium oxide paste, and then heat-treated in an air atmosphere (900 ° C., 1 hour), so that the surface of the base material and each recess are formed. A chromium oxide film was formed. As a result, a buried portion 211b buried in each concave portion was formed.

Next, a ceramic material slurry (crystallized glass or (Mn, Co) ₃ O ₄ ) shown in Table 1 is applied on the chromium oxide film and heat-treated (800-1000 ° C., 1-20 hours). A coating film was formed.

(Removal of coating film after thermal cycle test)
A thermal cycle test was performed on each sample. Specifically, a cycle of increasing the temperature to 800 ° C. at a rate of 300 ° C./hr, keeping the temperature for 1 hour, and then decreasing the temperature from 300 ° C./hr to 50 ° C. was repeated 10 times.

  Then, after performing the heat cycle test, the presence or absence of peeling of the coating film was confirmed for each sample. Specifically, in an image in which the cross section of the substrate was magnified 3000 times by FE-SEM, it was confirmed whether or not the coating film was peeled off from the substrate together with the chromium oxide film. The results are shown in Table 1. In Table 1, those with microscopic peeling in cross-sectional observation by FE-SEM are evaluated as Δ, and those without microscopic peeling are evaluated as ○.

  In addition, the average depth, the standard deviation of the depth, and the difference between the maximum value and the minimum value of the depth were calculated for ten buried portions randomly selected on the FE-SEM image.

  As shown in Table 1, the chromium oxide film has a plurality of embedded portions narrowed by openings of a plurality of concave portions formed on the surface of the base material, and the average depth of the plurality of embedded portions is 0.7 μm or more. In Examples 1 to 14, the peeling of the coating film could be suppressed as compared with Comparative Examples 1 to 3. Such a result was obtained because the adhesion of the chromium oxide film to the substrate could be improved by exhibiting a sufficient anchor effect as a whole of the plurality of buried portions having a suitable average depth. It is.

REFERENCE SIGNS LIST 100 Cell stack device 200 Manifold 201 Top plate 210 Base 210a Surface 210b Concave portion 211 Chromium oxide film 211a Surface 211b Embedded portion 212 Coating film 250 Cell stack

Claims (5)

A substrate composed of an alloy material containing chromium;
A chromium oxide film covering at least part of the surface of the substrate;
A coating film covering at least a part of the surface of the chromium oxide film,
With
The base material has a plurality of recesses respectively formed on the surface,
The chromium oxide film has a plurality of embedded portions embedded inside each of the plurality of recesses,
Each of the plurality of buried portions is narrowed at an opening of each of the plurality of recesses,
In the cross section of the base material, the average depth of the plurality of embedded portions is 0.7 μm or more,
Alloy members. The standard deviation of the depth of each of the plurality of buried portions is 0.2 or more,
The alloy member according to claim 1. The difference between the maximum value and the minimum value of the depth of each of the plurality of buried portions is 0.5 μm or more.
The alloy member according to claim 1. An electrochemical cell;
An alloy member according to any one of claims 1 to 3,
With
The alloy member is a current collecting member electrically connected to the electrochemical cell,
Cell stack. An electrochemical cell;
An alloy member according to any one of claims 1 to 3,
With
The alloy member is a manifold that supports a base end of the electrochemical cell,
Cell stack equipment.

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