JP2011175901A - Separator material for fuel cell, separator for fuel cell using the same, and fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separator material for a fuel cell capable of strongly and uniformly forming an Au layer or a layer including Au in the surface of a titanium base material and capable of securing adhesiveness and corrosion resistance to be required for a separator for a fuel cell. <P>SOLUTION: In the separator material for the fuel cell, an alloy layer 6 made of Cr and Au or an Au single layer 8 is formed in the surface of the Ti base material 2, and an intermediate layer 2a including Ti, O and Cr and including Au of less than 20 mass% exists between the alloy layer or the Au single layer and the Ti base material. As going to lower layers from a depth of 1 nm from the outermost surface, the maximum content of C to a depth, at which Ti of 50 mass% is included, is 10 mass% or less. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

Conventionally, a solid polymer type fuel cell separator in which a gas flow passage is formed on a carbon plate has been used, but there is a problem that material costs and processing costs are high. On the other hand, when a metal plate is used instead of the carbon plate, corrosion and elution become a problem because it is exposed to an oxidizing atmosphere at a high temperature. For this reason, a technique for forming a conductive portion by sputtering a noble metal selected from Au, Ru, Rh, Pd, Os, Ir, Pt and the like and an alloy of Au on the surface of the Ti plate is known. (Patent Document 1). Further, Patent Document 1 describes that the oxide of the noble metal is formed on the Ti surface.
On the other hand, a fuel cell separator is known in which an Au film is formed on an oxide film of a Ti base material through an intermediate layer made of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, or the like. (Patent Document 2). This intermediate layer has good adhesion to the base oxide film, that is, good bonding with O (oxygen atom), and good adhesion and bonding to the Au film because of the metal or metalloid. .

  Furthermore, a technique for improving acid resistance by forming a titanium oxide film on the surface of a Ti plate having a high carbon concentration and further depositing gold on the oxide film is known (Patent Document 3).

In addition, in a polymer electrolyte fuel cell, a direct methanol fuel cell (DMFC) that uses methanol that is easy to handle as a fuel gas to be supplied to an anode has been developed. Since DMFC can directly extract energy (electricity) from methanol, a reformer or the like is not necessary, and it can cope with downsizing of the fuel cell, and is also promising as a power source for portable devices.
The following two structures have been proposed as DMFC structures. First, the first structure is a single cell (stacked (active) structure in which a membrane electrode assembly (hereinafter referred to as MEA) in which a solid polymer electrolyte membrane is sandwiched between a fuel electrode and an oxygen electrode) is stacked. This structure is a planar type (passive type) structure in which a plurality of single cells are arranged in the plane direction, each of which is a structure in which a plurality of single cells are connected in series (hereinafter referred to as a stack). Of these, the passive type structure does not require an active fuel transfer means for supplying fuel gas (fuel liquid), air, or the like into the cell, and therefore further reduction in size of the fuel cell is considered promising. (Patent Document 4).

By the way, the separator for a fuel cell has electrical conductivity, electrically connects each unit cell, collects energy (electricity) generated in each unit cell, and supplies fuel gas ( A flow path for fuel liquid) and air (oxygen) is formed. This separator is also called an interconnector, a bipolar plate, or a current collector.
The conditions required for a DMFC current collector are more than those for a polymer electrolyte fuel cell separator using hydrogen gas. That is, in addition to the corrosion resistance to a sulfuric acid aqueous solution required for a normal polymer electrolyte fuel cell separator, the corrosion resistance to a methanol aqueous solution and the corrosion resistance to a formic acid aqueous solution are required. Formic acid is a by-product generated when hydrogen ions are produced from methanol on the anode catalyst.
Thus, under the DMFC operating environment, the material used for the conventional polymer electrolyte fuel cell separator is not always applicable.

JP 2001-297777 A JP 2004-185998 A JP 2009-289511 A JP-A-2005-243401

However, in the case of the technique described in Patent Document 1 described above, 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 base material, and the oxide film is not sufficiently removed. Has a problem that the adhesion of the noble metal film is lowered.
Patent Document 2 stipulates that a conductive thin film is formed on the surface of the oxide film on the surface of the base material. For example, Au should be formed while leaving the oxide film on the surface of the titanium base material. Then, the film is not uniformly formed. In particular, in wet gold plating, if the electrodeposition shape of the plating is granular and an oxide film remains on the surface of the titanium base material, a portion that becomes a non-plating portion is generated on a part of the surface of the titanium base material. In addition, Patent Document 2 stipulates that an intermediate layer is provided in order to improve the adhesion, but it is sufficient to simply provide the intermediate layer, and sufficient corrosion resistance and a corrosion resistance necessary for a fuel cell separator Durability cannot be obtained.
The technique described in Patent Document 4 is obtained by coating a base material with stainless steel clad on both surfaces of a copper plate, and cannot be said to have excellent corrosion resistance.

For this reason, the present inventors have studied to improve the adhesion of Au to the titanium substrate by sputtering Cr and Au on the surface of the titanium substrate to form an intermediate layer containing Cr. Yes.
However, when the amount of carbon present on the surface of the titanium base material increases, the sputtered Cr and carbon form carbides due to the heat generated during sputtering, and this carbide formation initially adheres uniformly to the base material surface. The dispersed Cr is dispersed in a sparse (island-like) state. Similarly, Au deposited on Cr is dispersed in a sparse (island-like) state, and there is a portion where the titanium substrate is exposed. As a result, it was found that even if the film adhesion immediately after sputtering was good, the sputtered film was peeled off and contact resistance increased when the corrosion resistance test was performed. This phenomenon is similar to the sensitization that occurs in stainless steel.
The cause of the carbon increase on the surface of the titanium base material is the titanium base manufacturing process (from cold rolling to annealing) before sputtering, and annealing without fully degreasing the rolling oil used for cold rolling. This is because the carbon, which is the main component of the rolling oil, burned onto the titanium base material.
Further, when the surface roughness of the titanium material is rough, the carbon is not sufficiently degreased and tends to remain on the surface of the titanium base material.

  That is, the present invention has been made in order to solve the above-described problems, and can form a highly corrosion-resistant conductive film containing Au on the surface of a titanium base material with high adhesion, under the fuel cell operating environment. However, an object of the present invention is to provide a fuel cell separator material having high durability, a fuel cell separator using the material, and a fuel cell stack.

As a result of various studies, the present inventors have formed an intermediate layer containing Ti, O and Cr on the surface of the Ti base material while reducing the amount of C (carbon) on the surface of the Ti base material, and alloyed the intermediate layer. It has been found that by forming a layer or a single Au layer, an Au (alloy) layer can be formed firmly and uniformly on Ti, and the corrosion resistance and durability required for a fuel cell separator can be secured.
In order to achieve the above object, the fuel cell separator material of the present invention is formed by forming an alloy layer of Cr and Au, or an Au single layer on the surface of a Ti base, and the alloy layer or the Au single layer. Between Ti and the Ti base material, there is an intermediate layer containing Ti, O and Cr and less than 20% by mass of Au, from the depth of 1 nm from the outermost surface to the lower layer, to a depth where Ti becomes 50% by mass The maximum content of C is 10% by mass or less.

The surface roughness of the outermost surface is preferably 0.2 μm or less.
The Ti base material may be formed by forming a Ti film having a thickness of 10 nm or more on the surface of a base material different from Ti.
The separator material for a fuel cell of the present invention is suitably used for a polymer electrolyte fuel cell or a direct methanol type polymer electrolyte fuel cell.

The fuel cell separator of the present invention uses the fuel cell separator material, and after the reaction gas flow path and / or the reaction liquid flow path are formed in advance on the Ti base material by pressing, the alloy layer or the Au single layer Formed.
Further, the fuel cell separator of the present invention uses the fuel cell separator material, and after forming the alloy layer or the Au single layer on the Ti base material, the reaction gas flow path and / or the reaction liquid flow by press working. It forms a road.

  The fuel cell stack of the present invention uses the fuel cell separator material or the fuel cell separator.

  According to the present invention, by regulating the amount of C on the surface of the Ti substrate, an Au layer or a layer containing Au can be formed firmly and uniformly on Ti, and the adhesion required for a fuel cell separator And corrosion resistance can be secured.

It is a schematic diagram which shows the structure of the separator material for fuel cells which concerns on the 1st Embodiment of this invention. It is a schematic diagram which shows the structure of the separator material for fuel cells which concerns on the 2nd Embodiment of this invention. It is a schematic diagram which shows the structure of the separator material for fuel cells which concerns on the 3rd Embodiment of this invention. It is a figure which shows the XPS analysis result of the separator material for fuel cells which concerns on Example 3. FIG. It is a figure which shows the XPS analysis result of the separator material for fuel cells which concerns on the comparative example 3. It is sectional drawing of the fuel cell stack (single cell) which concerns on embodiment of this invention. It is a top view which shows the structure of the separator concerning embodiment of this invention. It is a top view which shows the structure of the gasket concerning embodiment of this invention. 1 is a cross-sectional view of a planar fuel cell stack according to an embodiment of the present invention. It is a top view which shows the structure of the separator for planar fuel cells.

Hereinafter, a fuel cell separator material according to an embodiment of the present invention will be described. In the present invention,% means mass% (mass%) unless otherwise specified.
In the present invention, the “fuel cell separator” has electrical conductivity, electrically connects each single cell, collects energy (electricity) generated in each single cell, and collects each single cell. A fuel gas (fuel liquid) or air (oxygen) flow path is formed. The separator is also referred to as an interconnector, a bipolar plate, or a current collector.
Therefore, as will be described in detail later, as a separator for a fuel cell, in addition to a separator having an uneven flow path on a plate-like substrate surface, a plate-like substrate surface such as the above-described passive DMFC separator is used. It includes a separator with gas and methanol passage holes.

<First Embodiment>
Hereinafter, the fuel cell separator material according to the first embodiment of the present invention will be described. As shown in FIG. 1, the fuel cell separator material according to the first embodiment has a metal layer 4 formed on the surface of a Ti base 2 via an intermediate layer 2 a, and an alloy layer 6 on the surface of the metal layer 4. Is formed. The metal layer 4 is mainly made of Cr.

<Ti substrate>
The fuel cell separator material is required to have corrosion resistance and conductivity, and the base material is required to have corrosion resistance. For this reason, a titanium material with good corrosion resistance is used for the base material.
The Ti substrate may be a solid titanium material, or may be a Ti substrate having a thickness of 10 nm or more formed on the surface of a substrate different from Ti. Examples of the base material different from Ti include stainless steel and aluminum. By covering these surfaces with Ti, the corrosion resistance of stainless steel and aluminum having lower corrosion resistance than titanium can be improved. However, the corrosion resistance improving effect cannot be obtained unless Ti is covered by 10 nm or more.
The material of the Ti base material 2 is not particularly limited as long as it is titanium. Further, the shape of the Ti base material 2 is not particularly limited as long as it is a shape capable of sputtering Cr and gold. However, considering press forming into a separator shape, the shape of the Ti base material is preferably a plate material. The thickness of the entire Ti substrate is preferably 10 μm or more.
O (oxygen) contained in the intermediate layer 2a is naturally formed by leaving the Ti base 2 in the air, but O may be positively formed in an oxidizing atmosphere.

When the carbon present on the surface of the Ti base material increases, the sputtered Cr and carbon form carbides due to the heat generated during sputtering, and this carbide formation causes Cr to initially adhere uniformly to the base material surface. Are dispersed in a sparse (island-like) state. Similarly, Au deposited on Cr is dispersed in a sparse (island-like) state, and there is a portion where the titanium substrate is exposed. As a result, even if the adhesion of the film immediately after sputtering is good, when the corrosion resistance test is performed, the sputtered film is peeled off and the contact resistance increases.
For this reason, it is necessary that the C content from the depth of 1 nm to the lower layer from the outermost surface of the fuel cell separator material to the depth at which Ti becomes 50 mass% is 10 mass% or less.

Here, the Ti base material (Ti cold-rolled sheet) is generally subjected to a degreasing washing step for removing rolling oil after cold rolling. And after degreasing, it enters into an annealing process, and annealing is performed in a non-oxidizing gas or a batch type furnace in a vacuum. The cause of the increase in carbon on the surface of the base material is that the rolling oil used for cold rolling of the titanium base material before sputtering was annealed without sufficiently degreasing, so that the carbon that is the main component of the rolling oil was titanium. This is because it burned onto the base material. That is, the rolling oil is decomposed during annealing, and the carbon of the rolling oil component reacts with Ti to generate a carbon compound on the surface.
Further, the surface of the Ti base material is generally easy to become rough, and further, rolling of titanium tends to generate metal powder during rolling as compared with rolling of other metals. When the surface of the metal is rough, the rolling oil that has entered the concave portion of the surface, particularly the pit-like portion, cannot be sufficiently removed by simply immersing it in a cleaning solution or the like. In addition, if the degreasing and cleaning process is completed without removing the metal powder, oil remains between the metal powder and the material surface.

For this reason, by controlling the C content in the above-described depth range to 10% by mass or less, the adhesion of the Cr and gold sputtered films is improved, and the sputtered film can be obtained even if a corrosion resistance test is performed. The contact resistance can be kept low without peeling off. As a method of managing the C content to 10% by mass or less, it is possible to sufficiently degrease the Ti base material after cold rolling.
Specifically, in the degreasing cleaning process of the Ti base material after rolling, the cleaning effect is enhanced by stirring, vibration, brushing, ultrasonic treatment, etc., and removal of oil accumulated in the concave (pit-shaped) portion of the surface, The metal powder can be removed to reduce the oil content on the surface. As a result, it is possible to obtain a titanium material having a reduced C content on the surface after batch-type annealing in a non-oxidizing gas or vacuum. After the degreasing and cleaning step, physical polishing or chemical polishing may be performed. However, since the number of steps increases, it is preferable that the degreasing and cleaning step is performed.

Note that the Ti concentration is detected by XPS concentration detection, which will be described later, and the concentration (mass%) of each element is analyzed with the total of the designated elements as 100 mass%. The depth of 1 nm from the outermost surface of the fuel cell separator material is a distance (distance in terms of SiO ₂ ) on the horizontal axis (thickness direction) of the chart by XPS analysis.

Furthermore, it is preferable that the surface roughness (Ra) of the outermost surface of the separator material for a fuel cell of the present invention is 0.2 μm or less. The thickness of Cr and gold sputtered on the Ti base material is extremely thin compared to the surface roughness of the Ti base material, and the surface roughness of the outermost surface of the separator material for fuel cells substantially represents the surface roughness of the Ti base material. Yes.
The surface of the Ti substrate is rough compared to stainless steel, and the center line average roughness of the surface of the Ti rolled sheet often exceeds 0.2 μm. If the surface roughness of the Ti substrate is rougher than 0.2 μm, the carbon present on the surface is not sufficiently degreased and tends to remain on the surface of the Ti substrate. The surface roughness of the outermost surface of the fuel cell separator material (that is, substantially the surface roughness of the Ti base material) is more preferably 0.15 μm or less, and further preferably 0.1 μm or less.
In addition, Ra of a Ti rolled sheet changes with Ra of a rolling roll. When a Ti rolled sheet is continuously rolled in an actual production line, a roll of about Ra 0.06 μm is used. Titanium is softer than stainless steel, and tends to cause baking with the roll. For this reason, if it continues using the same roll without maintenance, Ra of a roll will become large and Ra of a Ti rolled sheet will also become large as a result. Therefore, by managing the Ra of the rolling roll, it is possible to continuously roll a Ti rolled sheet (base material) having a Ra of 0.2 μm or less.

<Alloy layer>
An alloy layer 6 of Cr and Au is formed on the Ti base 2. This alloy layer is for imparting Au characteristics (corrosion resistance, conductivity, etc.) and hydrogen embrittlement resistance to the Ti base material.
Cr has the properties that a) easily bonds with oxygen, b) constitutes an alloy with Au, and c) hardly absorbs hydrogen. It is formed to improve the adhesion between the alloy layer and the Ti base material.
In addition, Cr is more oxidizable than Au from the potential-pH diagram, and makes use of the characteristic that it is difficult to absorb hydrogen, so Cr is used as a constituent element of the following intermediate layer.

The alloy layer can be confirmed by XPS analysis which will be described later, and is a portion having a thickness of 1 nm or more with 50% by mass or more of Au from the outermost surface to the lower layer by XPS analysis, and a portion located above the following intermediate layer Is an alloy layer. The thickness of the alloy layer is preferably 1 to 100 nm. If the thickness of the alloy layer is less than 1 nm, the corrosion resistance required for the fuel cell separator may not be ensured on the Ti substrate. The thickness of the alloy layer is more preferably 2 nm or more, and further preferably 4 nm or more.
Further, heat treatment may be performed after forming the Cr and Au films. When heat treatment is performed, oxidation and diffusion proceed, and the Au concentration in the surface layer decreases and may be less than 50% by mass. However, if there is a region with a thickness of 3 nm or more and Au of 10% by mass or more and less than 50% by mass from the outermost surface to the lower layer, titanium does not diffuse into the surface layer and functions as an alloy layer.

If the thickness of the alloy layer exceeds 100 nm, it may not be possible to save money and the cost may increase.
In the alloy layer, when the Au concentration in the region of 1 nm or more thickness from the outermost surface to the lower layer is less than 50% by mass, or the Au concentration in the region of 3 nm or more thickness from the outermost surface to the lower layer is less than 10% by mass. In such a case, the corrosion resistance required for the fuel cell separator may not be ensured.

An Au single layer may be formed instead of the alloy layer 6. The Au single layer is a portion where the concentration of Au is approximately 100 wt% by XPS analysis, and the thickness of the Au single layer is required to be 1 nm or more.
Further, the alloy layer 6 may have a composition region (noble metal region) mainly composed of Cr on the intermediate layer side.

<Intermediate layer>
Between the alloy layer (or Au single layer) 6 and the Ti base material 2, there is an intermediate layer 2a containing Ti, O and Cr and less than 20% by mass of Au.
Usually, a Ti substrate has an oxide layer on the surface, and it is difficult to directly form an Au (containing) layer that is difficult to be oxidized on the Ti surface. On the other hand, it is considered that the metal is more easily oxidized than Au, and forms an O atom and an oxide in the Ti oxide on the surface of the Ti base, and is firmly bonded to the surface of the Ti base.
Further, the metal is difficult to absorb hydrogen. In these respects, when the thickness of the conductive film containing Au (the alloy layer or the Au single layer) is several tens of nm or less, conventionally, as an intermediate layer, simply Ti, Zr, Hf, V, Nb, Ta, Compared to the case of using Cr, Mo, W or the like, a separator material with excellent durability can be provided by forming the intermediate layer from Ti, O, and Cr.
The intermediate layer preferably contains no Au, and if 20 mass% or more of Au is contained, the adhesion is lowered. In order to set the Au concentration in the intermediate layer to less than 20% by mass, it is preferable to perform sputtering on the Ti base material using a Cr single target or a low Au concentration Cr—Au alloy target.

The intermediate layer is preferably present as a layer of 1 nm or more in which Ti and O are each 10% by mass or more and Cr is 20% by mass or more. In this case, when the cross section of the separator material for a fuel cell is analyzed by XPS, a region containing 10% by mass or more of Ti and 20% by mass or more of Cr and 20% by mass or more of Au is included in the thickness direction. 1 nm or more. The upper limit of the thickness of the intermediate layer having such a composition is not limited, but is preferably 100 nm or less from the viewpoint of the cost of Cr.
Here, a depth profile by XPS (X-ray photoelectron spectroscopy) analysis is measured, and concentration analysis of Au, Ti, O, Cr, and C is performed to determine the layer structure of the sputtered layer. In addition, the concentration detection by XPS analyzes the concentration (mass%) of each element by setting the total of designated elements as 100 mass%. In the XPS analysis, the distance of 1 nm in the thickness direction is the distance on the horizontal axis of the chart by XPS analysis (distance in terms of SiO ₂ ).

  The reason why the lower limit of Ti and O is 10% by mass and the lower limit of Cr is 20% by mass is that the portion where Cr is less than 20% by mass is close to the surface of the Ti substrate, and Ti is less than 10% by mass. This is because the portion is close to the alloy layer, and the portion where O is less than 10% by mass does not function as an intermediate layer because Cr and Ti do not form a sufficient oxide with O atoms. It is. Moreover, since Ti and O each decrease rapidly from 10% by mass, 10% by mass is set as the lower limit from the measurement. The reason for making Au less than 20% by mass is to improve adhesion.

<Metal layer>
The metal layer 4 is a single layer of Cr, and when forming the alloy layer and the intermediate layer, a part of Cr diffuses into the titanium oxide layer to form an intermediate layer, and a part of Cr diffuses to the surface side. Thus, an alloy layer with Au is formed, but Cr remaining as a layer without disappearing by diffusion forms the metal layer 4. Therefore, the metal layer 4 can be appropriately formed by changing the sputtering conditions (sputtering time, output) and the like.
However, since the presence of the metal layer 4 tends to deteriorate the corrosion resistance and durability, the thickness of the metal layer 4 is preferably 5 nm or less, more preferably 3 nm or less.
Note that the metal in the metal layer 4 and the Cr in the alloy layer 6 may be the same element or different elements.
The metal layer 4 can be confirmed by XPS analysis to be described later, and the thickness of the portion having a total of 70 mass% or more of Cr is defined as the thickness of the metal layer 4 by XPS analysis.

In the present invention, it is preferable that the O concentration in the depth where the Au concentration of the alloy layer 6 is 10% is 30% by mass or less.
The depth portion where the Au concentration of the alloy layer 6 is 10% indicates a region near the boundary between the intermediate layer 2a and the alloy layer 6, but when the O concentration of this portion increases, the corrosion resistance of the alloy layer 6 decreases, This is because the adhesion between the intermediate layer 2a and the alloy layer 6 may decrease.

It is preferable to have a gradient composition in which the proportion of Au in the alloy layer increases from the lower layer side toward the upper layer side. Here, the ratio (mass%) of Au can be obtained by the XPS analysis described above. The thickness of the alloy layer or the Au single layer is the actual scanning distance in the XPS analysis.
When the alloy layer has a gradient composition, the proportion of Cr that is more oxidizable than Au is higher on the lower layer side of the alloy layer and the bond with the Ti substrate surface becomes stronger, while the upper layer side of the alloy layer has the characteristics of Au. Since it becomes stronger, corrosion resistance and durability are improved.

<Manufacture of fuel cell separator materials>
As a method for forming the intermediate layer of the separator material for the fuel cell, the surface Ti oxide film of the Ti base material is not removed, and sputtering is performed on this base material using Cr as a target, thereby forming the O in the surface Ti oxide film. Cr can be bonded to each other to form an intermediate layer. In addition, after removing the surface Ti oxide film of the Ti base material 2, sputtering film formation is performed using Cr oxide as a target, or after removing the surface Ti oxide film of the Ti base material 2, sputtering is performed using Cr as a target in an oxidizing atmosphere. The intermediate layer can also be formed by forming a film.
During sputtering, the surface Ti oxide film on the Ti base material may be appropriately removed, and reverse sputtering (ion etching) may be performed for the purpose of cleaning the base material surface. Reverse sputtering can be performed, for example, by irradiating the substrate with argon gas at an output of about RF 100 W and an argon pressure of about 0.2 Pa.
However, as described above, the Ti base material has a maximum C content of 10% by mass or less from the depth of 1 nm from the outermost surface toward the lower layer and the depth at which Ti becomes 50% by mass. It is necessary to adjust the remaining amount of the surface Ti oxide film.
The Au of the intermediate layer is contained in the intermediate layer by Au atoms entering the intermediate layer by Au sputtering for forming the following alloy layer. Alternatively, sputter deposition may be performed on the surface of the Ti substrate using an alloy target containing Cr and Au.

As a method for forming the alloy layer, for example, Cr can be formed on the Ti base by the above-described sputtering, and then Au can be formed by sputtering 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 base, by sputtering Au there, Au enters the Cr film and becomes an alloy layer. Moreover, in this case, the composition becomes a gradient composition in which the proportion of Au in the alloy layer increases from the lower layer side toward the upper layer side.
Sputter film formation may be first performed on the Ti base material surface using an alloy target having a low Au concentration of Cr and Au, and then using an alloy target having a high Au concentration of Cr and Au.

<Second Embodiment>
Next, a fuel cell separator material according to a second embodiment of the present invention will be described. As shown in FIG. 2, the fuel cell separator material according to the second embodiment has an intermediate layer 2a formed on the surface of a Ti base 2 and an alloy layer 6 formed on the intermediate layer 2a.
. Since the Ti base material 2 and the alloy layer 6 are the same as those in the first embodiment, description thereof is omitted. The separator material for a fuel cell according to the second embodiment is in a state where the metal layer 4 in the first embodiment is not present, and is more excellent in corrosion resistance than the first embodiment.
Also in the second embodiment, it is preferable that the O concentration in the depth where the Au concentration of the alloy layer 6 is 10% is 30% by mass or less. The depth portion where the Au concentration of the alloy layer 6 is 10% indicates a region near the boundary between the intermediate layer 2a and the alloy layer 6, but when the O concentration of this portion increases, the corrosion resistance of the alloy layer 6 decreases, This is because the adhesion between the intermediate layer 2a and the alloy layer 6 may decrease.
Also in the second embodiment, as in the first embodiment, the thickness of the alloy layer is preferably 1 to 100 nm.

<Third Embodiment>
Next, a fuel cell separator material according to a third embodiment of the present invention will be described. As shown in FIG. 3, the fuel cell separator material according to the third embodiment has an alloy layer 6 formed on the surface of a Ti base 2 via an intermediate layer 2 a, and an Au single layer on the surface of the alloy layer 6. 8 is formed. Since the Ti base material 2 and the alloy layer 6 are the same as those in the first embodiment, description thereof is omitted.
The Au single layer 8 can be appropriately formed by changing sputtering conditions (sputtering time, output) and the like.

  The layer structure of the first and third embodiments is combined to form a layer structure in which the metal layer 4, the alloy layer 6, and the Au single layer 8 are formed in this order on the surface of the Ti base 2 via the intermediate layer 2a. Also good.

  According to the separator material for a fuel cell according to the embodiment of the present invention, an Au (alloy) layer can be formed firmly and uniformly on Ti, and this layer has conductivity, corrosion resistance and durability. It is suitable as a separator material for fuel cells. In addition, according to the embodiment of the present invention, if an Au (alloy) layer is formed by sputtering, this layer becomes a uniform layer, so that the surface becomes smoother than wet gold plating, and Au is wasted. There is an advantage that it is not necessary.

<Separator for fuel cell>
Next, an example of a fuel cell separator using the fuel cell separator material of the present invention will be described. The fuel cell separator is formed by processing the above-described fuel cell separator material into a predetermined shape, and a reaction gas flow path for flowing fuel gas (hydrogen) or fuel liquid (methanol), air (oxygen), cooling water, and the like. Alternatively, a reaction liquid channel (a groove or an opening) is formed.

<Laminated (active) fuel cell separator>
FIG. 6 is a cross-sectional view of a single cell of a stacked (active) fuel cell. In FIG. 6, current collector plates 140A and 140B are arranged outside the separator 10 described later. Usually, when a stack is formed by stacking single cells, a pair of current collectors is provided only at both ends of the stack. A board is placed.
The separator 10 has electrical conductivity, has a current collecting action in contact with an MEA described later, and has a function of electrically connecting each single cell. Further, as will be described later, the separator 10 is formed with a groove serving as a flow path for fuel gas and air (oxygen).

  In FIG. 6, 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) 80. An anode side gas diffusion film 90A and a cathode side gas diffusion film 90B are laminated on the surfaces of the anode electrode 40 and the cathode electrode 60, respectively. In the present invention, the membrane electrode assembly may be a laminate including the gas diffusion films 90A and 90B. For example, when a gas diffusion layer 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 is referred to as a membrane electrode assembly. May be.

On both sides of the MEA 80, the separator 10 is disposed so as to face the gas diffusion films 90A and 90B, respectively, and the separator 10 holds the MEA 80 therebetween. A flow path 10L is formed on the surface of the separator 10 on the MEA 80 side, and gas can enter and leave the interior space 20 surrounded by a gasket 12, a flow path 10L, and a gas diffusion film 90A (or 90B) described later. .
A fuel gas (hydrogen or the like) flows in the internal space 20 on the anode electrode 40 side, and an oxidizing gas (oxygen, air or the like) flows in the internal space 20 on the cathode electrode 60 side, so that an electrochemical reaction occurs. It has become.

The outer periphery of the periphery of the anode electrode 40 and the gas diffusion film 90 </ b> A is surrounded by a frame-shaped seal member 31 having substantially the same thickness as the laminated thickness. A substantially frame-shaped gasket 12 is interposed between the seal member 31 and the peripheral edge of the separator 10 so as to contact the separator, and the gasket 12 surrounds the flow path 10L. Furthermore, a current collector plate 140A (or 140B) is laminated on the outer surface of the separator 10 (the surface opposite to the MEA 80 side) in contact with the separator 10, and between the current collector plate 140A (or 140B) and the periphery of the separator 10 is stacked. A substantially frame-shaped sealing member 32 is interposed between the two.
The seal member 31 and the gasket 12 form a seal that prevents fuel gas or oxidizing gas from leaking out of the cell. When a plurality of single cells are stacked to form a stack, a gas different from the space 20 (when an oxidizing gas flows into the space 20) is formed in the space 21 between the outer surface of the separator 10 and the current collector plate 140A (or 140B). , Hydrogen flows in the space 21). Therefore, the seal member 32 is also used as a member for preventing gas from leaking outside the cell.

  The fuel cell is configured to include the MEA 80 (and the gas diffusion films 90A and 90B), the separator 10, the gasket 12, and the current collector plates 140A and 140B, and a fuel cell stack is configured by stacking a plurality of fuel cells. The

  Next, the structure of the separator 10 will be described with reference to the plan view 7. The separator 10 is formed into a rectangular shape by press working from the fuel cell separator material of the present invention, and a fuel gas introduction hole 10x is opened on the left side at the upper edge (upper side) of the separator 10. Further, a fuel gas discharge hole 10y is opened on the right side at the lower end edge (lower side) of the separator 10.

Furthermore, a plurality of linear flow channel grooves 10 </ b> L extending in parallel with the direction from the upper side to the lower side of the separator 10 (up and down direction in FIG. 7) are formed by pressing or the like. The straight flow path groove 10L generates a parallel flow in the gas flow.
Further, in this embodiment, the start and end of the linear flow channel 10L do not reach the outer edge of the separator 10, and a flat portion where the linear flow channel 10L is not formed exists on the outer peripheral edge of the separator 10. Further, in this embodiment, the adjacent linear flow path grooves 10L are positioned at equal intervals, but may be at unequal intervals.
In addition, positioning holes 10f are opened at opposing side edges (side edges) of the separator 10, respectively.

In addition, a flow path groove | channel may be not only a straight line but a curve, and each flow path groove does not necessarily need to be mutually parallel. Further, as a curve, for example, an S-shape may be used in addition to a curved line.
From the viewpoint of facilitating the formation of the flow channel, straight lines parallel to each other are preferable.
The thickness of the separator 10 is preferably 10 μm or more in terms of press formability, but is preferably 200 μm or less from the viewpoint of cost.

Next, the structure of the gasket 12 will be described with reference to the plan view 8.
The gasket 12 is in the form of a sheet made of, for example, Teflon (registered trademark), and the outer edge is a rectangular frame having the same size as the separator 10, and the inner edge is a fuel gas introduction hole 10 x, a discharge hole 10 y, and a linear flow. The fuel gas introduction hole 10x, the discharge hole 10y, and the linear flow path groove 10L are communicated with each other in the internal space of the gasket 12 so as to surround the road groove 10L.
In addition, positioning holes 12f are opened at opposite side edges (sides) of the gasket 12, and the gaskets 12 are stacked so as to overlap the positioning holes 10f of the separator 10, thereby making the relative relationship between the separator 10 and the gasket 12 different. Define the location.

  The material of the gasket 12 includes corrosion resistance, Teflon (registered trademark) having heat resistance at 80 to 90 ° C. which is the operating temperature of the fuel cell, and a metal plate (titanium, stainless steel, A sheet of aluminum) or a carbon material can be used. Although the thickness of the gasket 12 varies depending on the uneven shape of the separator 10, it is necessary to make the thickness equal to or greater than the groove height of the separator (the height difference between the frame portion and the concave or convex). For example, when the groove height of the separator 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 gasket 12 is positioned slightly above the upper end 10L1 of the linear flow channel, and a space is formed for the gas flowing along the linear flow channel 10L to turn back and turn 180 degrees. Further, the left end portion of the upper inner edge 12c extends outward so that the fuel gas introduction hole 10x of the separator 10 is exposed in the gasket 12.
Similarly, the lower inner edge 12d of the gasket 12 is positioned slightly below the lower end 10L2 of the linear flow channel, and there is a space for the gas flowing along the linear flow channel 10L to turn back and turn 180 degrees. Is formed. Further, the right end portion of the lower inner edge 12d extends outward, and the fuel gas discharge hole 10y of the separator 10 is exposed in the gasket 12.

Further, a piece-like partition member 12e1 extends inward at a position adjacent to a portion extending toward the fuel gas introduction hole 10x in the upper inner edge 12c. Further, another piece of partition member 12e2 extends inward at a position on the right side of the upper inner edge 12c by a predetermined distance from the partition member 12e1. And the front-end | tip of the partition members 12e1 and 12e2 is contacting the upper end (equivalent to a start end or a termination | terminus) 10L1 of a linear flow path groove.
Similarly, a piece-like partition member 12e3 extends inward at a position on the right side by a predetermined distance from the position facing the partition member 12e1 in the lower inner edge 12d. In addition, a piece of partition member inward toward the inside at a position on the lower inner edge 12d that is a predetermined distance to the right from the position facing the partition member 12e2 and adjacent to the portion extending toward the fuel gas discharge hole 10y. 12e4 extends. And the front-end | tip of the partition members 12e3 and 12e4 is contacting the lower end (equivalent to a start end or a termination | terminus) 10L2 of a linear flow path groove.

Further, the partition members 12e1 to 12e4 extending from the opposing inner edges 12c and 12d of the gasket 12 are the partition members 12e1 (upper inner edge 12c), 12e3 (lower inner edge 12d), and 12e2 (upper inner edge 12c) from the left side of FIG. , 12e4 (lower inner edge 12d).
Thus, since the partition members extending from the opposing inner edges of the gasket 12 are arranged in a staggered manner, the gas flow path flowing along the linear flow path groove 10L is folded back in the vicinity of the partition member, and the meandering flow path Will be configured.

  Specifically, the gas introduced into the separator 10 from the fuel gas introduction hole 10x flows downward in FIG. 8 along the linear flow path groove 10L, but the partition member 12e3 has one flow path groove 10L. Since it is in contact with the lower end, the flow along the flow path groove 10L is suppressed. Further, the flow crossing the flow channel 10L is originally suppressed. Therefore, the flow path groove 10L with which the partition member 12e3 is in contact functions as a dike that prevents both the flow in which the gas is short-cut in the horizontal direction (right direction in FIG. 8) and the flow in the vertical direction. The gas flow is folded back in the vicinity of the partition member 12e3, changes its direction by 180 degrees, and flows upward along the linear flow channel 10L. Next, since the partition members 12e1 and e2 similarly prevent the shortcut flow in the lateral direction, the gas flow is folded back in the vicinity of the partition member 12e2 and flows downward along the linear flow channel groove 10L. In the same manner, the gas flow is folded in the vicinity of the partition member 12e4, and after passing along the straight flow channel 10L, the right inner edge (side edge) of the gasket 12 is folded at this portion in order to prevent a shortcut flow. The fuel gas is discharged to the fuel gas discharge hole 10y along the straight flow channel 10L.

  The number of flow channel grooves in contact with one partition member is not particularly limited because it depends on the size of the separator and the size (width) of the flow channel grooves. Since the contributing groove is reduced, it is preferably 1 to 3 grooves.

  As described above, since the gas flow path in the separator becomes a meandering flow path due to the shape of the gasket that can be easily processed, it is not necessary to form a complicated flow path in the separator, and the flow path of the separator itself The power generation characteristics of the fuel cell can be improved by simplifying the shape and improving the gas flow without impairing productivity. That is, the parallel flow through the separator flow path can be changed to a serpentine flow (serpentine) depending on the shape of the gasket.

However, as a flow channel groove of the separator, a serpentine (meandering) shape may be used, and the shape of the flow channel is not limited.
The stacked (active) fuel cell shown in FIG. 6 can be applied not only to the above-described fuel cell using hydrogen as a fuel, but also to a DMFC using methanol as a fuel.

<Flat type (passive type) fuel cell separator>
FIG. 9 shows a cross-sectional view of a single cell of a planar (passive type) fuel cell. In FIG. 6, current collector plates 140A and 140B are arranged outside the separator 10 described later. Usually, when a stack is formed by stacking single cells, a pair of current collectors is provided only at both ends of the stack. A board is placed.
In FIG. 9, since the configuration of the MEA 80 is the same as that of the fuel cell of FIG. 6, the same reference numerals are given and description thereof is omitted (in FIG. 9, the description of the gas diffusion films 90A and 90B is omitted. Gas diffusion films 90A and 90B may be included).

In FIG. 9, the separator 100 has electrical conductivity, has a current collecting action in contact with the MEA, and has a function of electrically connecting each single cell. In addition, as will be described later, the separator 100 is formed with holes serving as fuel liquid and air (oxygen) flow paths.
The separator 100 is formed with a step portion 100s in the vicinity of the center of the long flat plate-like base material so that the cross section has a crank shape, an upper piece 100b positioned above the step portion 100s, and a step portion 100s. And a lower piece 100a located below. The step portion 100 s extends in a direction perpendicular to the longitudinal direction of the separator 100.
A plurality of separators 100 are arranged in the longitudinal direction, and a space is formed between the lower piece 100a and the upper piece 100b of the adjacent separators 100, and the MEA 80 is interposed in this space. A structure in which the MEA 80 is sandwiched between the two separators 100 is a single cell 300. In this way, a stack in which a plurality of MEAs 80 are connected in series via the separator 100 is configured.

FIG. 10 shows a top view of the separator 100. The lower piece 100a and the upper piece 100b each have a plurality of holes 100h, which serve as oxygen (air) reaction gas flow paths and methanol reaction liquid flow paths.
In this stack, when air (oxygen) is flowed from above in FIG. 9, oxygen comes into contact with the cathode electrode 60 side of the MEA 80 through the hole 100 h of the separator 100 and a reaction occurs. On the other hand, when methanol is allowed to flow from the lower side of FIG. 9, the methanol comes into contact with the anode electrode 40 side of the MEA 80 through the hole 100h of the separator 100, and a reaction occurs. Methanol is supplied from a tank (methanol cartridge) 200 in the lower part of FIG.
The planar (passive) fuel cell shown in FIG. 9 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 and number of openings of the planar (passive type) fuel cell separator are not limited, and the openings may be slits in addition to the holes described above, or the entire separator may be net-like.

In the fuel cell separator of the present invention, it is preferable that the reaction gas flow path and / or the reaction liquid flow path by press working are formed in advance on the Ti base material. In this way, it is not necessary to form a reaction gas channel (reaction liquid channel) in a later step, and the reaction gas can be easily processed by pressing the Ti substrate before forming the intermediate layer, the alloy layer, or the like. Since a flow path (reaction liquid flow path) can be formed, productivity is improved.
Further, in the fuel cell separator of the present invention, the reaction gas flow path and / or the reaction liquid flow path is formed later by press working on the fuel cell separator material in which the alloy layer or the Au single layer is formed on the surface of the Ti substrate. It may be formed. In the fuel cell separator material of the present invention, the alloy layer and the Au single layer are firmly adhered to the surface of the Ti base material. Road) and productivity is improved.

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

<Fuel cell stack>
The fuel cell stack of the present invention comprises the fuel cell separator material of the present invention or the fuel cell separator of the present invention.
The fuel cell stack is formed by connecting a plurality of cells in which an electrolyte is sandwiched between a pair of electrodes, and a fuel cell separator is interposed between the cells to block fuel gas and air. The electrode in contact with the fuel gas (H ₂ ) is the fuel electrode (anode), and the electrode in contact with the air (O ₂ ) is the air electrode (cathode).
The configuration example of the fuel cell stack is as already described with reference to FIGS. 6 and 9, but is not limited thereto.

<Cold rolling and degreasing of titanium material>
A strip of industrial pure titanium material (JIS type 1) having a thickness of 100 μm was cold-rolled while changing the centerline average surface roughness (Ra) of the rolling roll as follows, and the centerline average surface roughness (Ra) of Different Ti rolled plates (Ti substrates) were produced.
Ra of rolling roll:
(S) 0.06μm (new)
(T) 0.06μm (Used for a specified time: 1 ton rolling)
(U) 0.10μm (new)
(V) 0.10μm (Used for a predetermined time: 1 ton rolling)
(W) 0.10μm (Long-term use: Rolling more than 10 tons)
The surface roughness of the Ti rolled sheet and the rolling roll was measured using a non-contact type three-dimensional measuring device (manufactured by Mitaka Koki Co., Ltd., model NH-3) in accordance with JIS-B0601. The cut-off was 0.25 mm, the measurement length was 1.50 mm, and measurement was performed 5 times per sample.

Next, after cold rolling, a degreasing cleaning process was performed under different conditions as follows.
(A) The test piece was sufficiently immersed in a commercially available alkaline agent cleaning solution, and the surface was cleaned with a brush during the immersion (immersion time 60 seconds)
(B) The test piece was sufficiently immersed in a commercially available alkaline agent cleaning solution, but the surface was not cleaned with a brush (immersion time 60 seconds)
(C) The test piece was immersed in a commercially available alkaline cleaning solution, but the surface was not cleaned with a brush (immersion time: 10 seconds)
The Ti base material after the degreasing cleaning treatment was annealed.
<Preparation of sample>
Using the Ti base material after annealing as described above, pretreatment by FIB (focused ion beam processing) was performed. Next, Cr (metal film) was formed on the surface of the titanium oxide layer of the Ti base so as to have a predetermined target thickness by sputtering. Pure Cr was used for the target. Next, Au was deposited using a sputtering method so as to have a predetermined target thickness. Pure Au was used for the target.
The target thickness was determined as follows. First, an object (for example, Cr) is deposited on a titanium substrate in advance by sputtering, and the actual thickness is measured with a fluorescent X-ray film thickness meter (SEA5100 manufactured by Seiko Instruments, collimator 0.1 mmΦ), and the sputtering rate under this sputtering condition (Nm / min) was grasped. Based on the sputtering rate, the sputtering time for a thickness of 1 nm was calculated, and sputtering was performed under these conditions.
Sputtering of Cr and Au was performed using a sputtering apparatus manufactured by ULVAC, Inc. under the conditions of an output DC 50 W and an argon pressure of 0.2 Pa.

<Measurement of layer structure>
About the obtained sample, the depth (Depth) profile by XPS (X-ray photoelectron spectroscopy) analysis was measured, the density | concentration analysis of Au, Ti, O, Cr, and C was performed, and the layer structure of the sputter | spatter layer was determined. As an XPS device, ULVAC-PHI Co., Ltd. 5600MC was used, ultimate vacuum: 6.5 × 10 ⁻⁸ Pa, excitation source: monochromatic AlK, output: 300 W, detection area: 800 μmΦ, incident angle: 45 degrees, The take-off angle was 45 degrees, no neutralization gun was used, and the measurement was performed under the following sputtering conditions.
Ion species: Ar +
Acceleration voltage: 3 kV
Sweep area: 3mm x 3mm
Rate: 2 nm / min. (SiO ₂ equivalent)
In addition, the concentration detection by XPS analyzed the density | concentration (mass%) of each element by making the sum total of a designated element into 100 mass%. In the XPS analysis, the distance of 1 nm in the thickness direction is the distance on the horizontal axis of the chart by XPS analysis (distance in terms of SiO ₂ ).

FIG. 3 shows an actual XPS image of the sample cross section of Example 3. In FIG. 3, there is no alloy layer on the surface of the Ti base material, and an Au single layer (in this example, Au is regarded as approximately 100% when Au is 90% by mass or more) is formed on the outermost surface. Furthermore, it can be seen that there is 1 nm or more of an intermediate layer 2a in which Ti, O, and Cr are contained between the Ti base and the Au single layer and Au is less than 20% by mass. The intermediate layer was a portion containing 20 mass% or more of Cr.
Furthermore, it turns out that the maximum content of C is 10 mass% or less from the depth of 1 nm to the lower layer from the outermost surface to the depth where Ti becomes 50 mass%.
In the present invention, the concentration of Ti, O, etc. is defined in order to define the intermediate layer. Therefore, since the boundary of the intermediate layer is determined by the Ti and O concentrations for convenience, a layer different from both the intermediate layer and the Ti substrate may be interposed between the intermediate layer and the upper and lower layers (for example, the Ti substrate 2). is there.

<Preparation of each sample>
Samples of Examples 1 to 4 were produced by changing Ra of the rolling rolls to the titanium base material and keeping the target thicknesses of the Cr film and Au film during sputtering constant.
As Comparative Example 1, Ti was rolled using a rolling roll having a Ra of 0.1 μm and rolled for 1 ton, and similarly a Cr film and an Au film were sputtered.
As Comparative Example 2, Ti was rolled using a rolling roll having a Ra of 0.1 μm and rolled for 10 tons, and similarly a Cr film and an Au film were sputtered.
As Comparative Example 3, after rolling Ti using a new roll of Ra of 0.1 μm, as a degreasing cleaning method, after immersing the test piece in an alkaline agent cleaning solution for 10 seconds without cleaning the surface with a brush, Similarly, a Cr film and an Au film were sputtered.

<Evaluation>
The contact resistance was evaluated for each sample.
The contact resistance was measured by applying a load to the entire sample surface. First, carbon paper was laminated on one side of a 40 × 50 mm plate-like sample, and Cu / Ni / Au plates were further laminated on the sample and the outside of the carbon paper, respectively. The Cu / Ni / Au plate is a material in which a 10 μm thick copper plate is plated with 1.0 μm thick Ni, and the Ni layer is plated with 0.5 μm Au. The Au plated surface of the Cu / Ni / Au plate The carbon paper was placed in contact with it.
Further, a Teflon (registered trademark) plate was arranged outside the Cu / Ni / Au plate, and a load of 10 kg / cm ² was applied in the compression direction from the outside of each Teflon (registered trademark) plate with a load cell. In this state, when a constant current having a current density of 100 mA / cm ² was passed between the ^two Cu / Ni / Au plates, the electrical resistance between the Cu / Ni / Au plates was measured by a four-terminal method.

The contact resistance was measured before and after the corrosion test in which a sample (40 mm × 50 mm) was immersed in 350 cc of a sulfuric acid aqueous solution (bath temperature 80 ° C., concentration 0.5 g / L) for 240 hours.
Typical characteristics required for fuel cell separators are low contact resistance (10 mΩ · cm ² or less), corrosion resistance in the use environment (low contact resistance after corrosion test, and no elution of harmful ions (test) Ion concentration ≦ 0.1%)). Ion elution was analyzed by ICP.

  Table 1 shows the results. In Table 1, the maximum content of C from the depth of 1 nm from the outermost surface to the lower layer and the depth at which Ti becomes 50% by mass was the average value obtained by performing XPS analysis at three locations.

  As is clear from Table 1, the maximum content of C from the depth of 1 nm to the lower layer from the outermost surface to the depth at which Ti becomes 50% by mass is 10% by mass or less, and each intermediate layer was present. In the case of the examples, the contact resistance of the sample did not change before and after the corrosion resistance test, and the film adhesion and corrosion resistance were excellent.

In the case of each of the comparative examples in which the maximum C content from the depth of 1 nm to the lower layer from the outermost surface to the depth at which Ti becomes 50% by mass exceeds 10% by mass, the contact resistance of the sample is the target value after the corrosion resistance test. The adhesion and corrosion resistance of the coating were inferior.
FIG. 4 shows an actual XPS image of the sample cross section of Comparative Example 3.
Although the Au single layer and the intermediate layer exist, the maximum C content from the depth of 1 nm from the outermost surface to the lower layer and the depth at which Ti becomes 50 mass% exceeds 10 mass%.

2 Ti substrate 2a Intermediate layer 4 Metal layer (Cr single layer)
6 Alloy layer 8 Au single layer 10, 100 Separator 10L, 10LB (Gas) flow path 10L1, 10LB1 Flow channel groove start end 10L2, 10LB2 Flow path groove end 12, 12B Gasket 12c, 12d Gasket inner edge 12e1-12e4 Partition member 12eb1 to 12eb4 Gasket channel 20 Solid polymer electrolyte membrane 40 Anode electrode 60 Cathode electrode 80 Membrane electrode assembly (MEA)
100h hole (for separator)

Claims (8)

On the surface of the Ti substrate, an alloy layer of Cr and Au, or an Au single layer is formed,
Between the alloy layer or the Au single layer and the Ti base material, there is an intermediate layer containing Ti, O and Cr and less than 20% by mass of Au,
A fuel cell separator material having a maximum C content of 10% by mass or less from a depth of 1 nm from the outermost surface to a lower layer and a depth at which Ti becomes 50% by mass. The fuel cell separator material according to claim 1, wherein the surface roughness of the outermost surface is 0.2 μm or less. The separator material for a fuel cell according to claim 1 or 2, wherein the Ti substrate is formed by forming a Ti film having a thickness of 10 nm or more on a substrate surface different from Ti. The separator material for fuel cells according to any one of claims 1 to 3, which is used for a polymer electrolyte fuel cell. The separator material for a fuel cell according to claim 4, which is used for a direct methanol type polymer electrolyte fuel cell. A fuel cell separator using the fuel cell separator material according to any one of claims 1 to 5, wherein a reaction gas channel and / or a reaction liquid channel are formed in advance on the Ti base material by pressing. Thereafter, a fuel cell separator formed by forming the alloy layer or the Au single layer. A fuel cell separator using the fuel cell separator material according to any one of claims 1 to 5, wherein the alloy layer or the Au single layer is formed on the Ti base material, and then a reactive gas flow by press working A fuel cell separator formed by forming a channel and / or a reaction liquid channel. A fuel cell stack using the fuel cell separator material according to claim 1 or the fuel cell separator according to claim 6 or 7.

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