TWI447989B - A separator for a fuel cell, a separator for a fuel cell and a fuel cell stack for use thereof, and a method for manufacturing a separator material for a fuel cell - Google Patents

Description

Separator material for fuel cell, partition plate for fuel cell using the same, fuel cell stack, and method for manufacturing separator material for fuel cell

The present invention relates to a separator material for a fuel cell in which Au or an Au alloy (layer containing Au) is formed on a surface, a separator for a fuel cell using the same, and a fuel cell stack.

The solid polymer type separator for a fuel cell has been used for forming a gas flow path in a carbon plate, but there is a problem that material cost or processing cost is large. On the other hand, in the case where a metal plate is used instead of the carbon plate, corrosion or dissolution occurs due to exposure to an oxidizing atmosphere at a high temperature. For this reason, it is known that a surface of a Ti plate is sputter-deposited to form a conductive portion of a noble metal selected from the group consisting of Au, Ru, Rh, Pd, Os, Ir, and Pt, and Au (Patent Document 1). Further, Patent Document 1 discloses that an oxide of the noble metal is formed on the surface of Ti.

On the other hand, a fuel cell for forming an Au film on an oxide film of a Ti substrate via an intermediate layer made of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W or the like is known. Partition plate (Patent Document 2). The adhesion between the intermediate layer and the substrate oxide film, that is, the bonding property with O (oxygen atom) is good, and the adhesion to the Au film and the bonding property are good due to the metal or semimetal.

Further, in a polymer electrolyte fuel cell, a direct methanol fuel cell (DMFC) which uses methanol which is easy to handle as a fuel gas supplied to an anode has been developed. DMFC can directly extract energy from methanol (electric power) Therefore, it is possible to cope with the miniaturization of the fuel cell without using a reformer or the like, and it is also desirable to use it as a power source for the mobile device.

The construction of the DMFC is proposed in the following two ways. In the first structure, a laminated battery (active type) having a single cell (a membrane electrode assembly (hereinafter referred to as MEA) in which a solid electrode is sandwiched between a fuel electrode and an oxygen electrode) is used. The second structure is a planar (passive type) structure in which a plurality of unit cells are arranged in the planar direction. These configurations are all in which a plurality of unit cells are connected in series (hereinafter referred to as a stack), but the passive type structure does not require an active fuel delivery mechanism that supplies fuel gas (fuel liquid), air, or the like into the battery. Therefore, further miniaturization of the fuel cell can be expected (Patent Document 3).

Further, the separator for a fuel cell has electrical conductivity, electrically connects the cells, collects energy (electric power) generated in each cell, and supplies fuel gas (fuel liquid) or air (oxygen) to each cell. The flow path. The separator is also referred to as an internal connector, a bipolar plate, and a current collector.

Further, the conditions required for the collector for the DMFC are more than those required for the separator for the polymer electrolyte fuel cell using hydrogen. In other words, in addition to the corrosion resistance to the aqueous sulfuric acid solution required for the separator for a general polymer electrolyte fuel cell, it is required to have corrosion resistance to a methanol aqueous solution as a fuel and corrosion resistance to an aqueous formic acid solution. Formic acid is a by-product produced when hydrogen ions are generated from methanol on an anode catalyst.

Further, when chlorine (for example, from NaCl) is mixed in the methanol aqueous solution as a fuel, the corrosion resistance of the separator for a fuel cell is largely deteriorated. Therefore, the separator for a fuel cell is required to have corrosion resistance in an aqueous solution containing chlorine.

When it is assumed that both a polymer electrolyte fuel cell and a direct methanol fuel cell are used in the vicinity of the coast, the air as a fuel contains a large amount of chlorine. These chlorines are sucked into the fuel cell, and depending on the metal used in the separator, the characteristics may be greatly deteriorated due to chlorine. Therefore, it is necessary to carry out a corrosion resistance test of a chlorine-containing etching liquid, which is important (requires a separator for a fuel cell to have corrosion resistance in an aqueous solution containing chlorine).

Thus, in the DMFC operating environment, it is not always possible to directly apply the materials used in the separator for the polymer electrolyte fuel cell.

Patent Document 1: Japanese Laid-Open Patent Publication No. 2001-297777

Patent Document 2: Japanese Laid-Open Patent Publication No. 2004-185998

Patent Document 3: Japanese Laid-Open Patent Publication No. 2005-243401

However, in the case of the technique disclosed in the above Patent Document 1, in order to obtain an Au alloy film having good adhesion, it is necessary to remove the oxide film on the surface of the titanium substrate, and when the oxide film is insufficiently removed, there is a case where it is insufficient. The problem of the adhesion of the noble metal film is lowered.

Further, in Patent Document 2, a conductive film is formed on the surface of the oxide film on the surface of the substrate. For example, if Au is to be formed in a state in which an oxide film remains on the surface of the titanium substrate, uniform film formation cannot be performed. In particular, in the wet gold plating, the plating shape is granular, and if the oxide film remains on the surface of the titanium substrate, a part of the surface of the titanium substrate becomes a non-plated portion. Further, in Patent Document 2, in order to improve the adhesion, it is also possible to provide an intermediate layer containing Cr. However, according to the findings of the present inventors, it is clear that the corrosion resistance of the aqueous solution containing chlorine is deteriorated if the amount of adhesion of Cr is too large. .

The technique disclosed in Patent Document 3 is based on a case where a resin coated with a base material is coated on both sides of a copper plate, and the corrosion resistance is not excellent.

In other words, the present invention has been made to solve the above problems, and an object of the invention is to provide a conductive film which can form a high corrosion resistance of Au on a surface of a titanium substrate with high adhesion, even in an aqueous solution containing chlorine. A fuel cell separator material having high durability in a battery operating environment, and a fuel cell separator and a fuel cell stack are used.

As a result of various studies, the inventors of the present invention have found that by forming a surface layer containing Au and Cr on the surface of the Ti substrate, the ratio represented by (the amount of adhesion of Au) / (the amount of adhesion of Cr) is 10 or more. The Au-containing layer is firmly and uniformly formed on the Ti, and the corrosion resistance or durability required for the fuel cell separator is required in the aqueous solution containing chlorine.

In order to achieve the above object, the separator material for a fuel cell of the present invention forms a surface layer containing Au and Cr on the surface of the Ti substrate, and contains Ti, O, and Cr between the surface layer and the Ti substrate. Au is less than 20 atom% of the intermediate layer, and the thickness of the region having an Au concentration of 65 atom% or more is 1.5 nm or more, and the maximum concentration of Au is 80 atom% or more, and the adhesion amount of Au is 9000 to 40,000 ng/cm ² (Au The ratio of the adhesion amount / (the adhesion amount of Cr) is 10 or more, and the adhesion amount of Cr is 200 ng / cm ² or more. In the intermediate layer, Ti and O respectively contain 10 atom% or more and Cr contains 20 atoms. More than 1 nm is present in the region above %.

The Ti substrate may be formed by forming a Ti film having a thickness of 10 nm or more on a surface of a substrate different from Ti.

The separator material for a fuel cell of the present invention can be preferably used for a solid polymer fuel cell or a direct methanol type polymer electrolyte fuel cell.

In the separator for a fuel cell of the present invention, the separator material for a fuel cell is used, and a reaction gas flow path and/or a reaction liquid flow path formed by press working are formed in advance on the Ti substrate. Forming the surface layer. .

Further, in the fuel cell separator, the fuel cell separator material is used, and the surface layer is formed on the Ti substrate to form a reaction gas flow path formed by press working and/or The reaction liquid flow path is formed.

In the fuel cell stack of the present invention, the fuel cell separator material or the fuel cell separator is used.

The method for producing a separator material for a fuel cell according to the present invention is for producing the above-mentioned separator material for a fuel cell, and after dry-forming the Cr on the surface of the Ti substrate, dry-forming Au.

Preferably, the dry film formation is sputtering.

According to the present invention, the Au-containing layer can be formed firmly and uniformly on Ti, and the adhesion and corrosion resistance in the aqueous solution containing chlorine required for the fuel cell separator can be ensured.

Hereinafter, a separator material for a fuel cell according to an embodiment of the present invention will be described. In the present invention, the term "%" means an atom (at)% unless otherwise specified.

In the present invention, the term "a separator for a fuel cell" means having electrical conductivity, electrically connecting the cells, collecting energy (electric power) generated in each cell, and forming a supply to each cell. The flow of fuel gas (fuel liquid) or air (oxygen). The partition plate is also referred to as an internal connection body, a bipolar plate, and a current collector.

Therefore, the partition plate for a fuel cell includes, in addition to the partition plate having the flow path of the uneven shape on the surface of the plate-like base material, the partition plate of the passive type DMFC, and the surface of the plate-shaped base material. A partition plate having a flow path hole for gas or methanol, which will be described later.

As shown in Fig. 1, a separator material for a fuel cell according to an embodiment of the present invention is formed by forming an intermediate layer 2a on the surface of the Ti substrate 2 and a surface layer 6 on the surface of the intermediate layer 2a.

<Ti substrate>

The separator material for fuel cells is required to have corrosion resistance and electrical conductivity, and the substrate needs corrosion resistance. Therefore, the base material uses a titanium material having good corrosion resistance.

The Ti substrate may be a pure titanium material, or may be formed by forming a Ti film having a thickness of 10 nm or more on the surface of a substrate different from Ti. Examples of the substrate different from Ti include stainless steel, aluminum, copper, etc., and since the surface is coated with Ti, the corrosion resistance of stainless steel, aluminum, copper, or the like which is lower than that of titanium can be improved. However, if Ti is not covered by 10 nm or more, the corrosion resistance improvement effect cannot be obtained.

The material of the Ti substrate 2 is not particularly limited as long as it is titanium. Further, the shape of the Ti substrate 2 is not particularly limited, and may be a shape in which Cr and gold may be sputtered. However, in consideration of press molding into a separator shape, the shape of the Ti substrate is preferably a plate material. It is preferably a sheet material having a thickness of the entire Ti substrate of 10 μm or more.

The O (oxygen) contained in the intermediate layer 2a can be naturally formed by placing the Ti substrate 2 in the air, and can form O actively in an oxidizing atmosphere.

In addition, the concentration of Ti was measured by concentration detection of XPS described later, and the total of the designated elements was set to 100%, and the concentration (atomic %) of each element was analyzed. Further, the depth of 1 nm from the outermost surface of the separator material for a fuel cell means the distance (the distance in terms of SiO ₂ ) of the horizontal axis (thickness direction) of the graph by XPS analysis.

<surface layer>

A surface layer 6 having a thickness of 1.5 nm or more in a region containing Cr and Au and having a Au concentration of 65% or more is formed on the Ti substrate 2. The surface layer is used to impart properties (corrosion resistance, electrical conductivity, etc.) or hydrogen embrittlement resistance to the Ti substrate Au.

Cr has a property of being easy to bond with oxygen, b) alloying with Au, c) having difficulty in absorbing hydrogen, imparting the above functions to the surface layer, and forming an intermediate layer to improve adhesion between the surface layer and the Ti substrate.

Further, the Cr self-potential-pH diagram shows that Au is oxidizable, and it is difficult to absorb hydrogen, and Cr is used as a constituent element of the following intermediate layer.

The surface layer can be confirmed by XPS analysis described later, and the portion containing Au and Cr from the outermost surface facing the lower layer according to the XPS analysis, and the portion above the intermediate layer (the portion of Au above 20%) is used as the surface. Floor. The thickness of the surface layer is preferably from 5 to 100 nm. When the thickness of the surface layer is less than 5 nm, the corrosion resistance required for the separator for a fuel cell on the Ti substrate may not be secured. The thickness of the surface layer is more preferably 7 nm or more, and still more preferably 10 nm or more.

Further, heat treatment may be performed after forming Cr and Au. When the heat treatment is performed, oxidation and diffusion may also occur, resulting in a decrease in the Au concentration of the surface layer. However, when the thickness of the region having an Au concentration of 65% or more is 1.5 nm or more, titanium does not diffuse in the surface layer, and functions as a surface layer.

If the thickness of the surface layer exceeds 100 nm, there is a case where it is impossible to save money and the cost increases.

Further, in the case where the thickness of the region having a Au concentration of 65% or more is less than 1.5 nm in the surface layer, the corrosion resistance required for the separator for a fuel cell cannot be ensured.

Further, the maximum concentration of Au in the surface layer 6 must be 80% or more. When the maximum concentration of Au is less than 80%, the properties of the Au (corrosion resistance, electrical conductivity, etc.) or hydrogen embrittlement resistance cannot be sufficiently imparted to the Ti substrate.

Further, an Au single layer may be formed on the outermost surface portion of the surface layer 6. The Au single layer was analyzed according to XPS, and the concentration of Au was almost 100%.

Further, on the intermediate layer side of the surface layer 6, a composition region (precious metal region) mainly composed of Cr may be provided.

<intermediate layer>

Between the surface layer (or Au separate layer) 6 and the Ti substrate 2, there is an intermediate layer 2a containing Ti, O and Cr and having less than 20% of Au.

Usually, the Ti substrate has an oxide layer on the surface, and it is difficult to form an Au (containing) layer which is difficult to oxidize directly on the surface of Ti. On the other hand, it is considered that the above metal is more susceptible to oxidation than Au, and an oxide is formed on the surface of the Ti substrate and the O atom in the Ti oxide, and is firmly bonded to the surface of the Ti substrate.

Moreover, it is difficult for the above metal to absorb hydrogen. From the viewpoints of the above, when the thickness of the conductive film containing Au (the above-mentioned surface layer or Au single layer) is several 10 nm or less, only Ti, Zr, Hf, V, Nb, Ta, Cr, Mo are used previously. When the intermediate layer is formed from Ti, O, and Cr as compared with the case where W or the like is an intermediate layer, a separator having good durability can be provided.

Further, it is preferable that Au is not contained in the intermediate layer, and if Au is contained in an amount of 20% or more, the adhesion is lowered. In order to make the Au concentration in the intermediate layer less than 20%, it is preferred to perform sputtering on the Ti substrate using a Cr monomer target or a low Au concentration Cr-Au alloy target.

It is preferable that the adhesion amount of Cr is 200 ng/cm ² or more, and in the intermediate layer, Ti and O are each contained in an amount of 10% or more and Cr is contained in an amount of 20% or more and 1 nm or more. In this case, when the cross section of the separator material for a fuel cell is analyzed by XPS, Ti and O are contained in an amount of 10% or more and Cr is contained in an amount of 20% or more, and a region containing 20% or more of Au is present in a thickness direction of 1 nm or more. The upper limit of the thickness of the intermediate layer having such a composition is not limited, and is preferably 100 nm or less from the cost of Cr.

When the adhesion amount of Cr is 200 ng/cm ² , since the Cr is small, the adhesion of the surface layer may be deteriorated.

Here, the depth (Depth) distribution analyzed by XPS (X-ray photoelectron spectroscopy) is measured, and the concentration analysis of Au, Ti, O, and Cr is performed to determine the layer structure of the sputter layer. Further, the concentration of each element was analyzed by setting the total of the designated elements to 100% by the concentration detection system of XPS. In addition, the distance of 1 nm in the thickness direction in the XPS analysis means the distance (the distance in terms of SiO ₂ ) of the horizontal axis of the graph by XPS analysis.

The reason why the lower limit of Ti and O is 10%, and the lower limit of Cr is 20% is that the portion where Cr is less than 20% is close to the surface of the Ti substrate, and the portion where Ti is less than 10% is close to the surface layer. Further, it is considered that Cr and Ti cannot form a sufficient oxide with the O atom in the portion where O is less than 10%, and the function of the intermediate layer cannot be exerted. Further, since Ti and O were each reduced from 10%, the measurement was 10% as the lower limit. The reason for setting Au to less than 20% is to improve adhesion. When the intermediate layer is less than 1 nm, Cr is thin, and the portion where the Ti substrate is in contact with Au is increased, so that the adhesion of the surface layer may be deteriorated.

In the separator material for a fuel cell of the present invention, the adhesion amount of Au must be 9000 to 40,000 ng/cm ² .

When the adhesion amount of Au is less than 9000 ng/cm ² , the corrosion resistance required for the fuel cell separator is not secured.

On the other hand, in terms of saving money, the adhesion amount of Au must be less than 40,000 ng/cm ² . Moreover, the ratio represented by (the adhesion amount of Au) / (the adhesion amount of Cr) is 10 or more. If the adhesion amount of Au is less than 40,000 ng/cm ² , the ratio of (Amount of adhesion of Au) / (the amount of adhesion of Cr) is less than 10, and there is a portion where the surface of the sputtered film is exposed to Cr, and is corroded by chlorine. In the corrosion resistance test in the liquid, the contact resistance after the test increases, and the dissolution of Cr is also large.

The upper limit of the ratio (the amount of adhesion of Au) / (the amount of adhesion of Cr) is not particularly limited. However, if the ratio is too large, the ratio of Cr is decreased, and the adhesion of the surface layer due to Cr cannot be ensured. Therefore, the above comparison is preferably 100 or less. If the ratio is too large, the amount of adhesion of Au is more than necessary, and the cost is increased. Therefore, the above comparison is preferably 50 or less. More preferably, the ratio is 30 or less, and more preferably 20 or less.

In the present invention, it is preferred to form an oxide layer having less than 50% of Ti and 20% or more of O between the Ti substrate and the surface layer 6 in a thickness of less than 100 nm. Sometimes a portion of the oxide layer coincides with a region of the intermediate layer.

If an oxide layer is present, the titanium substrate can be prevented from embrittlement in the case of performing a continuous power generation test of the fuel cell. A portion of Ti which is less than 50% is considered to be a part of a non-titanium substrate because the amount of titanium is one-half or less of the total amount. Further, since an oxide film exists on the surface of the titanium substrate, the position from the portion where Ti is less than 50% to the surface layer is an oxide layer. The reason why the region containing 20% or more of O is used as the oxide layer is that if the O (oxygen) concentration of the oxide layer is less than 20%, the titanium substrate is embrittled when the continuous power generation test of the fuel cell is performed. The durability of the separator material for a fuel cell is deteriorated.

However, when the thickness of the oxide layer is 100 nm or more, the adhesion or conductivity of the surface layer may be lowered. On the other hand, when the oxide layer is thin, when the continuous power generation test of the fuel cell is performed, the titanium substrate is also embrittled, and the durability of the separator material for the fuel cell is deteriorated. Therefore, the thickness of the oxide layer is preferably 5 nm or more, more preferably 10 nm or more.

The proportion of Au in the surface layer is preferably an increasing composition increasing from the lower layer side toward the upper layer side. Here, the ratio (at%) of Au can be obtained by the above XPS analysis. The thickness of the surface layer is the actual size of the scanning distance in the XPS analysis.

If the surface layer is of increasing composition, the proportion of Cr which is oxidizable in the lower layer side of the surface layer is more than that of Au, and the bonding with the surface of the Ti substrate is strong, and on the other hand, the property of Au in the layer side above the surface layer becomes strong. Therefore, corrosion resistance and durability are improved.

<Manufacture of separator material for fuel cell>

In the method for forming an intermediate layer of a separator material for a fuel cell, the Ti oxide film on the surface of the Ti substrate is not removed, and the substrate is sputter-deposited with Cr as a target, whereby Cr and the surface Ti oxide film are used. The O bond is formed so that an intermediate layer can be formed. Further, after removing the Ti oxide film on the surface of the Ti substrate 2, sputtering may be performed by sputtering an oxide of Cr or after removing the Ti oxide film on the surface of the Ti substrate 2, and then targeting Cr. Sputtering is performed in an oxidizing atmosphere to form an intermediate layer.

Further, at the time of sputtering, the Ti oxide film on the surface of the Ti substrate can be appropriately removed, and reverse sputtering (ion etching) can be performed for the purpose of cleaning the surface of the substrate. The reverse sputtering can be performed, for example, by an output power of about 100 W RF and an argon pressure of about 0.2 Pa to irradiate the substrate with argon gas.

The Au of the intermediate layer can cause Au atoms to enter the intermediate layer by Au sputtering for forming the surface layer, whereby the intermediate layer contains Au. Further, an alloy target containing Cr and Au may be used to form a film on the surface of the Ti substrate.

In the method of forming the surface layer, for example, Cr can be formed on the Ti substrate by the above-described sputtering, and then Au can be sputter-deposited on the Cr film. In this case, since the sputtered particles have high energy, even if only the Cr film is formed on the surface of the Ti substrate, Au can be deposited on the Cr film by sputtering Au thereon to form a surface layer. Further, in this case, the ratio of Au in the surface layer is an increasing composition which increases from the lower layer side toward the upper layer side.

On the surface of the Ti substrate, an alloy target having a low Au concentration among Cr and Au may be used for sputtering, and then an alloy target having a high Au concentration among Cr and Au may be used for sputtering. .

According to the separator material for a fuel cell according to the embodiment of the present invention, the Au-containing layer can be firmly and uniformly formed on Ti, and the layer is electrically conductive, corrosion-resistant, and durable, and thus is suitable as a fuel cell separator. Board material. Further, according to the embodiment of the present invention, when the layer containing Au is sputter-deposited to form a film, the layer becomes a uniform layer. Therefore, compared with the wet gold plating, the surface has a smooth surface and does not waste the use of Au.

<Fuel separator for fuel cell>

Next, an example of a fuel cell separator using the separator material for a fuel cell of the present invention will be described. In the fuel cell separator, the fuel cell separator material is processed into a specific shape to form a reaction for circulating fuel gas (hydrogen), fuel liquid (methanol), air (oxygen), cooling water, and the like. a gas flow path or a reaction liquid flow path (slot or opening).

<Layered (active) fuel cell separator>

Fig. 3 is a cross-sectional view showing a unit cell of a laminated type (active type) fuel cell. Further, the current collector plates 140A and 140B are disposed on the outer sides of the partition plate 10 to be described later in FIG. 3, and generally, when the battery cells are stacked to form a stack, only a pair of current collector plates are disposed at both ends of the stack. .

Further, the partition plate 10 has electrical conductivity, and has a current collecting function in contact with an MEA to be described later, and has a function of electrically connecting the unit cells. Further, as will be described later, a groove serving as a flow path of fuel gas or air (oxygen) is formed in the partition plate 10.

In FIG. 3, an anode electrode 40 and a cathode electrode 60 are laminated on both sides of the solid polymer electrolyte membrane 20 to constitute a membrane electrode assembly (MEA, Membrane Electrode Assembly) 80. Further, on the surfaces of the anode electrode 40 and the cathode electrode 60, a gas diffusion film 90A is laminated on the anode side, and a gas diffusion film 90B is laminated on the cathode side. In the present invention, when a membrane electrode assembly is mentioned, it may be a laminate including gas diffusion membranes 90A and 90B. Further, for example, when a gas diffusion layer or the like is formed on the surface of the anode electrode 40 or the cathode electrode 60, the laminated body of the solid polymer electrolyte membrane 20, the anode electrode 40, and the cathode electrode 60 may be referred to as a membrane electrode assembly.

The partition plate 10 is disposed on both sides of the MEA 80 so as to face the gas diffusion films 90A and 90B, respectively, and the partition plate 10 sandwiches the MEA 80. A flow path 10L is formed on the surface of the partition plate 10 on the MEA 80 side, and the gas can be introduced into the internal space 20 surrounded by the gasket 12, the flow path 10L, and the gas diffusion film 90A (or 90B).

In addition, an oxidizing gas (oxygen, air, or the like) flows through the internal space 20 on the cathode electrode 60 side by the fuel gas (hydrogen or the like) flowing through the internal space 20 on the anode electrode 40 side, thereby generating an electrochemical reaction.

The anode electrode 40 and the outer side of the edge of the gas diffusion film 90A are surrounded by a frame-shaped sealing member 31 having a thickness almost the same as the thickness of the laminate. Further, between the sealing member 31 and the edge of the partitioning plate 10, a substantially frame-shaped gasket 12 that is in contact with the partitioning plate is inserted, and the gasket 12 surrounds the flow path 10L. Further, a collector plate 140A (or 140B) that is in contact with the partition plate 10 is laminated on the outer surface of the partition plate 10 (the surface opposite to the MEA 80 side), and the collector plate 140A (or 140B) and the partition plate are laminated. Between the edges of 10, a substantially frame-shaped sealing member 32 is inserted.

The sealing member 31 and the gasket 12 form a seal for preventing the fuel gas or the oxidizing gas from leaking out of the unit. Further, when a plurality of unit cells are stacked to form a stack, a gas different from the space 20 flows through the space 21 between the outer surface of the partition plate 10 and the current collector plate 140A (or 140B) (circles in the space 20) In the case of an oxidizing gas, hydrogen flows in the space 21). Therefore, the sealing member 32 also functions as a member that prevents gas from leaking out of the unit.

Further, the MEA 80 (and the gas diffusion films 90A and 90B), the partition plate 10, the gasket 12, and the current collector plates 140A and 140B are included to constitute a fuel cell unit, and a plurality of fuel cell units are stacked to constitute a fuel cell stack.

Next, the configuration of the partitioning plate 10 will be described with reference to a plan view 4. The partition plate 10 is formed into a rectangular shape by press working by the separator material for a fuel cell of the present invention, and the fuel gas introduction hole 10x is opened to the left side at the upper edge (upper end) of the partition plate 10. Further, at the lower edge (lower end) of the partitioning plate 10, the fuel gas discharge hole 10y is opened to the right side.

Further, a plurality of linear flow path grooves 10L extending in parallel from the upper end of the partition plate 10 toward the lower end (upward and downward in FIG. 4) are formed by press working or the like. The linear flow path groove 10L causes a parallel flow of the air flow.

Further, in this embodiment, the start end and the end of the linear flow path groove 10L do not reach the outer edge of the partition plate 10, and the outer edge of the partition plate 10 has a flat portion where the linear flow path groove 10L is not formed. Further, in this embodiment, the adjacent linear flow path grooves 10L are arranged at equal intervals, but they may be unequal intervals.

Further, positioning holes 10f are formed in the opposite side edges (sides) of the partitioning plate 10, respectively.

Furthermore, the flow path grooves may be not only straight lines but also curved lines, and the flow path grooves are not necessarily parallel to each other. Further, the curve may have an S shape, for example, in addition to the curved line.

From the viewpoint of easily forming the flow path grooves, it is preferable that the lines are parallel to each other.

The thickness of the partition plate 10 is preferably 10 μm or more from the viewpoint of press formability, and is preferably 200 μm or less from the viewpoint of cost.

Next, the configuration of the gasket 12 will be described with reference to a plan view 5.

The gasket 12 is, for example, a sheet shape composed of Teflon (registered trademark), and the outer edge is a rectangular frame having substantially the same size as the partition plate 10, and the inner edge thereof is formed to surround the fuel gas introduction hole 10x, the discharge hole 10y, and The linear flow path groove 10L has a substantially rectangular shape, and the fuel gas introduction hole 10x, the discharge hole 10y, and the linear flow path groove 10L communicate with each other in the internal space of the gasket 12.

Further, in the opposite side edges (sides) of the gasket 12, positioning holes 12f are respectively opened, and the gasket 12 is laminated in such a manner as to coincide with the positioning holes 10f of the partitioning plate 10, thereby defining the partitioning plate 10 and the gasket. The relative position of 12.

For the material of the gasket 12, a metal having a corrosion resistance and a heat resistance at a working temperature of a fuel cell, that is, a heat resistance of 80 to 90 ° C, can be used to form a metal having a corrosion-resistant and conductive noble metal. Plate (titanium, stainless steel, aluminum, etc.) or carbon. The thickness of the gasket 12 varies depending on the uneven shape of the partition plate 10, but it must be equal to or higher than the groove height of the partition plate (the height difference between the frame portion and the concave or convex portion). For example, when the groove height of the partition plate is 0.5 mm, the thickness of the gasket is 0.5 mm.

Next, the shape of the gasket 12 will be described in more detail. The upper inner edge 12c of the washer 12 is located slightly above the upper end 10L1 of the linear flow path groove, and forms a space for returning the gas flowing through the linear flow path groove 10L and turning it by 180 degrees. Further, the left end portion of the upper inner edge 12c extends to the outside, and the fuel gas introduction hole 10x of the partition plate 10 is displayed in the gasket 12.

Similarly, the lower inner edge 12d of the washer 12 is located slightly below the lower end 10L2 of the linear flow path groove, and a space for returning the gas flowing through the linear flow path groove 10L and turning 180 degrees is formed. Further, the right end portion of the lower inner edge 12d extends to the outside, and the fuel gas discharge hole 10y of the partition plate 10 is exposed inside the gasket 12.

Further, in the upper inner edge 12c, a sheet-shaped spacer member 12e1 extends inwardly at a position adjacent to a portion extending toward the fuel gas introduction hole 10x. Further, in the upper inner edge 12c, a further sheet-shaped spacer member 12e2 extends toward the inner side at a position on the right side of the specific distance from the spacer member 12e1. Further, the distal ends of the partition members 12e1 and 12e2 are in contact with the upper end (corresponding to the start end or the terminal end) 10L1 of the linear flow path groove.

Similarly, in the lower inner edge 12d, the sheet-shaped spacer member 12e3 extends inward toward the inner side at a position on the right side of the position facing the spacer member 12e1. Further, in the lower inner edge 12d, a sheet-shaped spacer member 12e4 extends inwardly from a position on the right side of the position facing the spacer member 12e2 and adjacent to the portion extending toward the fuel gas discharge hole 10y. Further, the distal ends of the partition members 12e3 and 12e4 are in contact with the lower end (corresponding to the start end or the terminal end) 10L2 of the linear flow path groove.

Further, the partition members 12e1 to 12e4 extending from the inner edges 12c and 12d of the washer 12, respectively, from the left side of FIG. 5, with the partition members 12e1 (upper inner edge 12c), 12e3 (lower inner edge 12d), 12e2 (upper inner edge 12c) and 12e4 (lower inner edge 12d) are arranged in this order.

In this manner, the partition members extending from the inner edges of the washers 12 are arranged in a staggered manner. Therefore, the gas flow path that flows along the linear flow path grooves 10L returns to the vicinity of the partition members to constitute a turbulent flow path.

Specifically, the gas introduced into the partition plate 10 from the fuel gas introduction hole 10x flows downward along the linear flow path groove 10L toward the lower side of FIG. 5, and the partition member 12e3 is in contact with the lower end of one flow path groove 10L, so that the The flow path of the flow path groove 10L is suppressed. Further, the flow path that traverses the flow path groove 10L is originally suppressed. Therefore, the flow path groove 10L that the partition member 12e3 is in contact with is a flow path that prevents direct flow of gas in the lateral direction (the right direction in FIG. 5) and a diversion of any of the flow paths in the longitudinal direction. Since the function is performed, the airflow returns to the front side of the partition member 12e3 by 180 degrees, and flows upward along the linear flow path groove 10L. Then, since the partition members 12e1 and e2 are similarly prevented from directly traversing in the lateral direction, the airflow returns to the vicinity of the partition member 12e2 and flows downward along the linear flow path groove 10L. Similarly, in the same manner, the airflow returns to the vicinity of the partition member 12e4, and after the linear flow path groove 10L, since the right inner edge (side edge) of the gasket 12 prevents direct cross flow, the linear flow path groove 10L is returned after the portion is returned. The fuel gas discharge hole 10y is discharged.

Further, the number of the flow path grooves in which one spacer member is connected depends on the size of the partition plate or the size (width) of the flow path groove, and is not particularly limited. However, if the number is too large, the gas is assisted. Since the number of grooves for circulation is reduced, it is preferably 1 to 3.

As described above, by processing the shape of the gasket which is easy, the gas flow path in the partition plate is configured as a turbulent flow path, so that it is not necessary to form a complicated flow path in the partition plate, so that the partition plate itself flows. The shape of the road is simplified, and the circulation of the gas can be improved without impairing the productivity, and the power generation characteristics of the fuel cell can be improved. That is, the parallel flow formed by the flow path of the partition plate can be changed to a turbulent flow (serpentine) by the shape of the gasket.

In particular, the flow path grooves of the partition plates may be connected in a serpentine shape, and the shape of the flow path grooves is not limited.

The laminated (active) fuel cell shown in Fig. 3 can be applied to a DMFC using methanol as a fuel, in addition to the above-described fuel cell using hydrogen as a fuel.

<Plane type (passive type) fuel cell separator board>

Fig. 6 is a cross-sectional view showing a unit cell of a planar type (passive type) fuel cell. Further, in FIG. 6, the current collector plates 140A and 140B are disposed on the outer sides of the partition plate 10 to be described later. Generally, when the battery cells are stacked to form a stack, only a pair of current collector plates are disposed at both ends of the stack. .

In FIG. 6, the configuration of the MEA 80 is the same as that of the fuel cell of FIG. 5, and therefore the same reference numerals will be given thereto, and the description thereof will be omitted (in FIG. 6, the disclosure of the gas diffusion films 90A and 90B is omitted, but the gas diffusion film 90A may be provided. 90B).

In FIG. 6, the partitioning plate 100 has electrical conductivity, and has a collecting function in contact with the MEA, and has a function of electrically connecting the respective cells. Further, as will be described later, a hole serving as a flow path of a fuel liquid or air (oxygen) is formed in the partition plate 100.

The partition plate 100 has a segment portion 100s formed in the vicinity of the center of the elongated flat substrate so as to have a cross-sectional shape in the shape of a crank. The partition plate 100 is located above the upper side plate 100b and the segment portion 100s via the segment portion 100s. The lower side panel 100a is located below. The segment portion 100s extends in the vertical direction in the longitudinal direction of the partition plate 100.

Further, a plurality of partition plates 100 are arranged in the longitudinal direction, and a space is formed between the lower side panel 100a and the upper side panel 100b adjacent to the partitioning plate 100, and the MEA 80 is inserted into the space. The structure in which the MEA 80 is sandwiched by the two partition plates 100 serves as the unit cell 300. In this manner, the plurality of MEAs 80 are connected in series via the partition plate 100 to constitute a stack.

Fig. 7 shows a top view of the partitioning plate 100. A plurality of holes 100h are opened in the lower side sheet 100a and the upper side sheet 100b, respectively, and become a reaction gas flow path of oxygen (air) or a reaction liquid flow path of methanol.

In the stack, if air (oxygen) flows from above the figure 6, it passes through the hole 100h of the partition plate 100, and the cathode electrode 60 side of the MEA 80 is brought into contact with oxygen to cause a reaction. On the other hand, when methanol flows from the lower side of FIG. 6, it passes through the hole 100h of the partition plate 100, and the anode electrode 40 side of the MEA80 is contacted with methanol, and a reaction arises. Further, methanol was supplied from a storage tank (methanol) 200 below the FIG.

The planar (passive) fuel cell shown in Fig. 6 can be applied to a fuel cell using hydrogen as a fuel, in addition to the above-described DMFC using methanol as a fuel. Further, the shape or the number of the openings of the partition plate for the flat type (passive type) fuel cell is not limited, and the opening may be a slit in addition to the hole, or the entire partition plate may be a mesh. .

In the separator for a fuel cell of the present invention, it is preferred that a reaction gas flow path and/or a reaction liquid flow path be formed on the Ti substrate by press working in advance. By doing so, it is not necessary to form a reaction gas flow path (reaction liquid flow path) in the subsequent step, and the reaction gas flow path can be easily formed by press working the Ti substrate before forming the intermediate layer or the surface layer or the like. (Reaction liquid flow path), so productivity is improved.

Further, in the separator for a fuel cell of the present invention, a separator material for a fuel cell in which a surface layer or an Au single layer is formed on a surface of a Ti substrate may be formed, and then a reaction gas stream is formed by press working. Road and / or reaction liquid flow path. Since the surface layer or the Au single layer of the separator material for a fuel cell of the present invention is firmly adhered to the surface of the Ti substrate, even after the film formation, the reaction can be formed without peeling off the film. The gas flow path (reaction liquid flow path) improves productivity.

In addition, in order to perform press working for forming a reaction gas flow path (reaction liquid flow path), it is preferable that the thickness of the Ti base material is 10 μm or more as a separator material for a fuel cell. The upper limit of the thickness of the Ti substrate is not limited, but it is preferably 200 μm or less from the viewpoint of cost.

<fuel cell stack>

The fuel cell stack of the present invention is obtained by using the fuel cell separator material of the present invention or the fuel cell separator.

In the fuel cell stack, a plurality of cells each having an electrolyte sandwiched between a pair of electrodes are connected in series, and a fuel cell separator is interposed between the cells to block fuel gas or air. The electrode to which the fuel gas (H ₂ ) is in contact is the fuel electrode (anode), and the electrode to which the air (O ₂ ) is contacted is the air electrode (cathode).

The configuration example of the fuel cell stack has been described with reference to FIGS. 3 and 6, but is not limited thereto.

[Examples]

<Production of sample>

As the Ti substrate, an industrial pure titanium material (one type of JIS) having a thickness of 100 μm was used, and pretreatment was performed by FIB (Focused Ion Beam Processing). When observed by energy dispersive fluorescent X-ray analysis (EDX) by FE-TEM (electrolytic radiation type transmission electron microscope), it was confirmed that a titanium oxide layer of about 10 nm was formed in advance on the surface of the Ti substrate.

Further, in some of the examples, a pure stainless steel material (SUS316L) having a thickness of 100 μm or pure copper (C1100) having a thickness of 100 μm was used, and a Ti having a specific thickness shown in Table 1 (Ti coating material) was coated. The coating of Ti was carried out by vacuum evaporation using an electron beam evaporation apparatus (manufactured by ULVAC, MB05-1006).

Next, Cr is formed on the surface of the titanium oxide layer of the Ti substrate by sputtering to form a specific target thickness. The target uses pure Cr. Next, Au is formed by sputtering to form a specific target thickness. The target used pure Au.

The target thickness is as specified below. First, an object (Cr, Au) is formed by sputtering on a titanium substrate in advance, and the actual thickness is measured by a fluorescent X-ray film thickness meter (SEA 5100 manufactured by Seiko Instruments, collimator: 0.1 mm Φ). Sputter rate (nm/min) under sputtering conditions. Further, based on the sputtering rate, a sputtering time of 1 nm thick was calculated, and sputtering was performed under the conditions.

The sputtering of Cr and Au was carried out using a sputtering apparatus manufactured by ULVAC Co., Ltd. under the conditions of an output of DC 50 W and an argon pressure of 0.2 Pa.

<Measurement of layer structure>

The obtained sample was subjected to XPS (X-ray photoelectron spectroscopy) analysis to measure the depth (Depth) distribution, and the concentration analysis of Au, Ti, O, and Cr was performed to determine the layer structure of the sputter layer. XPS device uses 5600MC manufactured by ULVAC-PHI Co., Ltd., ultimate vacuum: 6.5×10 ^-8 Pa, excitation source: monochromatic AlK, output power: 300W, detection area: 800μmΦ, incident angle: 45 degrees, exit angle : 45 degrees, no neutralization gun, measured under the following sputtering conditions.

Ion species: Ar+

Acceleration voltage: 3kV

Scanning area: 3mm × 3mm

Rate: 2 nm/min (calculated as SiO ₂ )

Further, the concentration of each element was set to 100% by the concentration detection system of XPS, and the concentration (at%) of each element was analyzed. In addition, the distance in the thickness direction of 1 nm in the XPS analysis means the distance (the distance in terms of SiO ₂ ) of the horizontal axis of the graph by XPS analysis.

Fig. 2 is a view showing an actual XPS image of a cross section of the sample of Example 1.

It is understood that a surface layer 6 composed of Cr and Au is formed on the surface of the Ti substrate 2. Further, between the Ti substrate 2 and the surface layer 6, there is an intermediate layer 2a containing 1 nm or more and containing Ti, O, and Cr, respectively, and having less than 20% of Au.

Further, it is understood that an oxide layer having less than 50% of Ti and 20% or more of O is formed from the side of the Ti substrate 2 of the surface layer 6 to a thickness of less than 100 nm.

Further, in the present invention, the concentration of Ti, O, etc. is defined to define the intermediate layer. Therefore, the boundary of the intermediate layer can be conveniently determined by the concentration of Ti and O. Therefore, a layer different from the intermediate layer and the Ti substrate may be sandwiched between the intermediate layer and the upper and lower layers (for example, the Ti substrate 2). .

<Production of each sample>

The titanium substrate (pure Ti, Ti coating material) having different thicknesses of the surface Ti oxide layer at the initial stage was subjected to various changes in the target thicknesses of the Cr film and the Au film at the time of sputtering, and the samples of Examples 1 to 11 were produced. .

As Comparative Example 9, a sample was produced by reducing the sputtering thickness of the Au film to 4 nm.

In Comparative Examples 10, 14, and 15, a sample was prepared by setting the adhesion amount of Au/the adhesion amount of Cr to less than 10.

As Comparative Example 11, a sample was produced by reducing the sputter thickness of the Cr film to 0.25 nm.

As Comparative Example 12, a sample was prepared by performing atmospheric heat treatment (120 ° C × 12 hours) after sputtering.

As Comparative Example 13, a substrate (300 ° C) was heated at the time of sputtering to prepare a sample.

<evaluation>

Each sample was subjected to the following evaluation.

A. Adhesiveness of the film

After the mesh was drawn at the interval of 1 mm on the outermost surface (surface layer) of each sample, the adhesive tape was adhered, and each test piece was bent by 180° to return to the original state, and the tape of the bent portion was quickly and strongly peeled off. , a peel test was performed.

The case where the film was not peeled off at all was set to ○, and even if it was peeled off, it was set as × as long as it was visually confirmed.

B. Contact resistance

The measurement of the contact resistance is carried out by applying a load to the entire surface of the sample. First, carbon paper was laminated on the front and back surfaces of a 40×50 mm plate-shaped sample, and Cu/Ni/Au plates were laminated on the outer side of the carbon paper on the front and back sides, respectively. The Cu/Ni/Au plate is plated on a 1.0 μm thick Ni substrate on a copper plate having a thickness of 10 mm, and a 0.5 μm Au material is plated on the Ni layer, and the Au plated surface of the Cu/Ni/Au plate is bonded to the carbon paper. Mode configuration.

Further, a Teflon (registered trademark) plate was placed on the outer side of the Cu/Ni/Au plate, and a load of 10 kg/cm ^{2 was} applied from the outside of each Teflon (registered trademark) plate in the compression direction by the load cell. In this state, when a constant current having a current density of 100 mA/cm ² was passed between two Cu/Ni/Au plates, the electric resistance between the Cu/Ni/Au plates was measured by a four-terminal method.

Further, the contact resistance was measured before and after the test sample according to the following two conditions.

Condition 1: Impregnation test in which the sample was immersed in an aqueous sulfuric acid solution (bath temperature: 90 ° C, sulfuric acid concentration: 0.5 g/L, immersion time: 240 hours, liquid volume: 1000 cc)

Condition 2 (aqueous solution containing chlorine); immersion test in which the sample was immersed in an aqueous solution of sulfuric acid (0.5 g/L) + sodium chloride (Cl: 10 ppm) (bath temperature 90 ° C, immersion time 240 hours, liquid volume 1000 cc)

C. Metal dissolution

The metal elution amount was evaluated by performing ICP (inductively coupled plasma) emission spectrometry on all the metal concentrations (mg/L) in the test liquids tested under the above conditions 1 and 2.

In addition, the representative characteristics required for the fuel cell separator are the following two points: low contact resistance (10 mΩ·cm ² or less) and corrosion resistance in the use environment (low contact resistance after corrosion resistance test, no Harmful ions are dissolved).

The results obtained are shown in Tables 1 and 2. Further, the presence of the intermediate layer and the oxide layer was confirmed by determining the ratio of each component from the actual XPS image of the sample cross section.

D. Adhesion amount

The amount of adhesion was evaluated by acid hydrolysis/ICP (inductively coupled plasma) emission spectroscopy. Specifically, a sample of 50 mm × 50 mm was completely dissolved in a nitric acid solution, and the adhesion amount of Au and Cr was analyzed. In addition, the number of samples per one condition was set to five, and the average value of the measurement results of five times was shown in Table 1, respectively.

It is understood from Tables 1 and 2 that the surface layer and the intermediate layer are present, and the thickness of the region where Au is 65 atom% or more is 1.5 nm or more, and the maximum concentration of Au is 80 atom% or more, (the adhesion amount of Au) / ( In the case of the examples in which the ratio of the adhesion amount of Cr is 10 or more, the contact resistance of the sample did not change before and after the corrosion resistance test in the chlorine-containing aqueous solution, and the adhesion between the film and the corrosion resistance were excellent.

In the case of Comparative Example 9 in which the Au adhesion amount was less than 9000 ng/cm ² , in the corrosion resistance test using the condition 2 with a chlorine-containing aqueous solution, the contact resistance after the test increased, and the amount of Cr dissolved under the condition 2 was also large. The film has poor corrosion resistance.

(Amount of adhesion of Au) / (the amount of adhesion of Cr) The ratio of the ratio of the ratio of the ratio of (the adhesion of Cr) is less than 10, in the case of the corrosion resistance test using the condition 2 of the aqueous solution containing chlorine, the contact after the test The electric resistance increases, and the amount of Cr eluted under the condition 2 is also large, and the corrosion resistance of the film is poor.

In the case of Comparative Example 11 in which the Cr adhesion amount was less than 200 ng/cm ² , the adhesion of the sputter film was deteriorated, and the evaluation of the corrosion resistance could not be performed.

In the case of Comparative Example 12 in which the maximum concentration of Au was less than 80 atomic % after atmospheric heat treatment after sputtering, in the corrosion resistance test of Condition 2, the contact resistance after the test increased, and the amount of Cr dissolved under Condition 2 was also More, the film has poor corrosion resistance.

In the case of Comparative Example 13 in which the thickness of the region where the Au concentration is 65% or more is less than 1.5 nm, in the corrosion resistance test of Condition 2, the contact resistance after the test increases, and the amount of Cr eluted under Condition 2 is also large, and the film is Corrosion resistance is poor.

2. . . Ti substrate

2a. . . middle layer

6. . . Surface layer

10,100. . . Partition plate

10L, 10LB. . . (gas) flow path

10L1, 10LB1. . . The beginning of the flow channel

10L2, 10LB2. . . End of flow channel

10f, 12f. . . Positioning hole

10x. . . Fuel gas introduction hole

10y. . . Fuel gas exhaust hole

12, 12B. . . washer

12c, 12d. . . Inner edge of the gasket

12e1~12e4. . . Spacer member

12eb1~12eb4. . . Washer flow path

20. . . Solid polymer electrolyte membrane

20 , 21 . . . space

31, 32. . . Sealing member

40. . . Anode electrode

60. . . Cathode electrode

80. . . Membrane electrode assembly (MEA)

90A, 90B‧‧‧ gas diffusion membrane

100h‧‧‧ (separate plate) hole

100s‧‧‧ Section

100a‧‧‧Upper side film

100b‧‧‧Bottom film

140A, 140B‧‧‧ collector board

200‧‧‧ storage tank (methanol)

300‧‧‧single battery

Fig. 1 is a schematic view showing the configuration of a separator material for a fuel cell according to an embodiment of the present invention.

Fig. 2 is a graph showing the results of XPS analysis of a cross section of the separator material for a fuel cell of Example 1.

Fig. 3 is a cross-sectional view showing a fuel cell stack (single cell) according to an embodiment of the present invention.

Fig. 4 is a plan view showing the structure of a partitioning plate according to an embodiment of the present invention.

Fig. 5 is a plan view showing the structure of a gasket according to an embodiment of the present invention.

Figure 6 is a cross-sectional view showing a planar fuel cell stack according to an embodiment of the present invention.

Fig. 7 is a plan view showing the structure of a partition plate for a flat type fuel cell.

Claims (10)

A separator material for a fuel cell, wherein a surface layer containing Au and Cr is formed on a surface of the Ti substrate, and Ti, O, and Cr are contained between the surface layer and the Ti substrate, and Au is less than 20 atomic %. In the intermediate layer, the thickness of the region having an Au concentration of 65 atom% or more is 1.5 nm or more, and the maximum concentration of Au is 80 atom% or more, and the adhesion amount of Au is 9000 to 40,000 ng/cm ² (the adhesion amount of Au) / (Cr) The ratio of the adhesion amount is 10 or more, and the adhesion amount of Cr is 200 ng/cm ² or more. In the intermediate layer, Ti and O are each contained in an amount of 10 atom% or more and Cr content of 20 atom% or more is 1 nm or more. . The separator material for a fuel cell according to the first aspect of the invention, wherein the Ti substrate is formed by forming a Ti film having a thickness of 10 nm or more on a surface of a substrate different from Ti. The separator material for a fuel cell according to claim 1 or 2, which is used for a polymer electrolyte fuel cell. The separator material for a fuel cell according to claim 1 or 2, which is used for a direct methanol type solid polymer fuel cell. For example, the separator material for a fuel cell according to item 3 of the patent application is used for a direct methanol type solid polymer fuel cell. A separator for a fuel cell, which is used in the patented scope A separator for a fuel cell of a separator material for a fuel cell according to any one of the fifth aspect, wherein the reaction gas flow path and/or the reaction liquid flow path formed by press working are formed in the Ti in advance After the substrate, the surface layer is formed. A separator for a fuel cell, which is a separator for a fuel cell according to any one of claims 1 to 5, wherein the surface layer is formed on the Ti base. After the material, a reaction gas flow path and/or a reaction liquid flow path formed by press working are formed. A fuel cell stack using the separator material for a fuel cell according to any one of claims 1 to 5, or the separator for a fuel cell according to claim 6 or 7. A method for producing a separator material for a fuel cell, which is used for manufacturing a separator material for a fuel cell according to any one of claims 1 to 5, after dry-forming the Cr on the surface of the Ti substrate , dry film forming Au. The method for producing a separator material for a fuel cell according to claim 9, wherein the dry film formation is sputtering.