JP2010045038A - Fuel cell and separator therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell and a separator therefor formed of titanium or a titanium alloy with excellent corrosion resistivity, high adherence to noble-metal layers, low contact resistance, and excellent productivity. <P>SOLUTION: The separator for the fuel cell includes a noble-metal layer with a thickness not smaller than 2 nm, containing more than one kind of rare metals selected from at least Ru, Rh, Pd, Os, Ir, Pt and Au, on the surface of a substrate formed of titanium or the titanium alloy. A titanium-oxide layer containing at least either of a rutile-type crystal or a brookite-type crystal is formed at least in either of the portion between the noble-metal layer and the substrate, or on the exposed surface of the substrate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell separator and a fuel cell made of Ti or Ti alloy for a polymer electrolyte fuel cell used for portable devices such as mobile phones and personal computers, household fuel cells, fuel cell vehicles and the like.

In recent years, fuel cells are expected as an energy source for solving global environmental problems and energy problems.
In particular, polymer electrolyte fuel cells can be operated at low temperatures, and can be reduced in size and weight, so they can be applied to household cogeneration systems, power supplies for portable devices, and fuel cell vehicles. It is being considered.

  Here, a general polymer electrolyte fuel cell has a catalyst layer serving as an anode and a cathode on both sides of a solid polymer membrane that is an electrolyte, a gas diffusion layer on the outer side, and a fuel gas flow on the outer side. The separator is provided with a path.

  This separator is required not only to function as a gas flow path but also to take out a current, and therefore has high conductivity. Conventionally, carbon separators have been used. However, because the thickness dimension has to be increased due to strength, it is difficult to say that it is preferable from the viewpoint of reducing the size and weight.

  In order to reduce the size and weight of the separator, it is considered that the separator is formed of a metal that can be thinned. However, since the inside of the fuel cell (solid polymer fuel cell) is in an acidic atmosphere, it can be said that the environment is easily corroded by metals. Therefore, a metal separator used in a fuel cell needs to have good corrosion resistance and conductivity.

  Also, metals such as stainless steel and Ti have good corrosion resistance by forming a passive film on the surface, but this passive film increases the contact resistance with the gas diffusion layer, so that the conductivity is improved. It is known to inhibit the power generation efficiency of the fuel cell.

  On the other hand, metals that do not form a passive film such as iron have good conductivity but are easily corroded and eluted, and the eluted ions deteriorate the catalytic properties and reduce the ionic conductivity of the solid polymer membrane. Therefore, it is known that the power generation characteristics of the fuel cell are deteriorated as a result.

For this reason, the surface of a metal separator is plated with gold (for example, see Patent Document 1), or the surface of a stainless steel or Ti separator is adhered to a surface of a noble metal or a noble metal alloy by ion deposition or plating ( For example, refer to Patent Document 2), and a structure in which a noble metal layer is formed on the surface of a separator made of a corrosion-resistant metal material (for example, refer to Patent Document 3) has been proposed.
These inventions attempt to maintain high corrosion resistance and low contact resistance by forming a noble metal having high corrosion resistance on a metal surface without forming a passive film on the surface.

JP-A-10-228914 JP 2001-6713 A JP 2004-158437 A

  However, the invention described in Patent Document 1 not only deteriorates the adhesion of gold unless the surface passive film is removed, but also increases the contact resistance due to this passive film (that is, the conductivity is low). Lower). Therefore, the passive film is removed by performing the surface activation process, but since the passive film is formed in the cleaning process performed before the plating process, there is a drawback that sufficient adhesion cannot be obtained. There is a disadvantage that the contact resistance cannot be lowered.

  Moreover, the invention described in Patent Document 2 performs a process of precipitating Pt as a noble metal by a corrosion reaction while mechanically polishing the surface of stainless steel or Ti. When such a treatment is performed, Pt is deposited on the portion where the passive film has been removed, so that the contact resistance decreases (that is, the conductivity increases), but the pinhole (where the substrate partially appears on the surface) In other words, stainless steel and Ti are eluted from the pinhole when used in an acidic atmosphere such as a fuel cell, and the power generation characteristics of the fuel cell deteriorate. There are drawbacks. In addition, although a method of blasting with glass beads plated with precious metal has been proposed, since the separator is required to have high dimensional accuracy, there is a drawback that it becomes difficult to use due to deformation that can occur by blasting. .

  In the invention described in Patent Document 3, since the noble metal layer is formed by plating, it is considered that the noble metal layer is formed on the passive film. For this reason, there are drawbacks that sufficient adhesion cannot be obtained and contact resistance cannot be lowered.

  An object of the present invention is to use a fuel cell separator made of Ti or Ti alloy having excellent corrosion resistance, high adhesion of a noble metal layer, low contact resistance, and excellent productivity, and the fuel cell separator. It is to provide a fuel cell.

  In order to solve the above-described problems, the separator for a fuel cell according to the present invention has at least one selected from Ru, Rh, Pd, Os, Ir, Pt and Au on the surface of a substrate made of Ti or Ti alloy. A rutile type crystal and a brookite type crystal are formed between at least one of the noble metal layer and the substrate, and a portion where the substrate is exposed on the surface. A titanium oxide layer containing at least one of the above is formed. The fuel cell separator is formed with a recess for forming a gas flow path through which gas flows in at least a part of the surface of the substrate, and the noble metal layer is formed on the surface of the substrate where the recess is formed. It may be formed.

  In the fuel cell separator according to the present invention, a titanium oxide layer containing at least one of a rutile type crystal and a brookite type crystal is formed between at least one of a noble metal layer and a substrate and a portion where the substrate is exposed on the surface. Therefore, the contact resistance can be lowered. That is, conductivity can be improved. Further, the adhesion between the noble metal crystal lattice and the crystallized passive film (titanium oxide layer) is enhanced to obtain adhesion with the noble metal layer. In the fuel cell separator of the present invention, the concave portion is formed on at least a part of the surface of the substrate, so that in the fuel cell, the solid polymer membrane disposed between the two fuel cell separators is formed. The gas can be efficiently supplied.

  The fuel cell according to the present invention preferably uses the above-described fuel cell separator. Since the fuel cell of the present invention uses the above-described fuel cell separator, it has excellent corrosion resistance, high adhesion of the noble metal layer, low contact resistance, and excellent productivity.

The fuel cell separator according to the present invention has excellent corrosion resistance, high adhesion of the noble metal layer, low contact resistance, and excellent productivity.
The fuel cell according to the present invention has excellent corrosion resistance, high adhesion of the noble metal layer, low contact resistance, and excellent productivity.

It is a flowchart explaining the process of the manufacturing method of the separator for fuel cells. It is sectional drawing of the separator for fuel cells which concerns on this invention. It is explanatory drawing explaining the measuring method of contact resistance. It is a figure which shows an example of the shape of the gas flow path formed in the surface of a board | substrate. It is a figure which shows a mode that a part of fuel cell using the separator for fuel cells of this invention was expand | deployed. It is a graph which shows the relationship between heat processing time (t) and heat processing temperature (T).

  DESCRIPTION OF EMBODIMENTS Embodiments for carrying out a fuel cell separator and a fuel cell according to the present invention will be described with reference to the drawings as appropriate.

The fuel cell separator 1 according to the present invention will be described in detail with reference to FIG.
As shown in FIG. 2, the fuel cell separator 1 according to the present invention has Ti or Ti formed with a recess for forming a gas flow path 11 (see FIG. 4) through which gas flows at least at a part of the surface. A noble metal layer 3 containing at least one kind of noble metal selected from Ru, Rh, Pd, Os, Ir, Pt and Au is formed on the surface of the alloy substrate 2. The fuel cell separator 1 can supply gas to the solid polymer membrane 13 disposed between the two fuel cell separators 1 and 1 in the fuel cell 20 via the gas diffusion layers 12 and 12 (FIG. 5), the concave portion may not be formed on the surface of the substrate 2.

More specifically, the fuel cell separator 1 according to the present invention includes at least one or more kinds of noble metals selected from Ru, Rh, Pd, Os, Ir, Pt and Au on the surface of the substrate 2. A noble metal layer 3 having a thickness of 2 nm or more is formed by the PVD method, and the noble metal layer 3 is heat-treated at a predetermined heat treatment temperature and a predetermined oxygen partial pressure to form the noble metal layer 3, and the noble metal layer 3 and the substrate The titanium oxide layer 5 containing at least one of a rutile type crystal and a brookite type crystal is formed in at least one of a portion between the two and a portion where the substrate 2 is exposed on the surface.
The significance of setting the thickness of the noble metal layer 3 in the above range, using the PVD method, and defining the heat treatment temperature and oxygen partial pressure of the heat treatment will be described later.

The thickness of the noble metal layer 3 formed on the substrate 2 is preferably 1.5 nm or more.
If the thickness of the noble metal layer 3 is less than 1.5 nm, the barrier effect of the noble metal layer 3 becomes insufficient, and a passive film is formed in the portion of the noble metal layer 3 and the substrate 2 immediately below the titanium oxide layer 5, resulting in contact resistance. May increase.
In addition, although there is no upper limit of the thickness of the noble metal layer 3, it is preferable that it is 500 nm or less from a viewpoint of cost.

  When the fuel cell separator 1 according to the present invention includes the titanium oxide layer 5, for example, as shown in FIG. 2, at least one selected from Ru, Rh, Pd, Os, Ir, Pt and Au is used. The titanium oxide layer 5 is formed between the noble metal layer 3 containing the above noble metal and the substrate 2 (that is, the base material). In addition, when the pinhole P etc. are formed in the noble metal layer 3, and the part which the board | substrate 2 exposed to the surface exists, the titanium oxide layer 5 can also be formed directly under the said pinhole P. FIG. In the present invention, it is preferable to form the titanium oxide layer 5 between the noble metal layer 3 and the substrate 2 and at least one of the portions where the substrate 2 is exposed on the surface (pinhole P). More preferred.

  If the titanium oxide layer 5 has a thickness of about 0.5 to 10 nm, it can have both a hydrogen absorption preventing effect and conductivity. Since the titanium oxide layer 5 is covered with the noble metal layer 3 or formed under a low oxygen partial pressure, the titanium oxide layer 5 contains at least one of a rutile type crystal and a brookite type crystal more than a normal passive film. obtain.

Next, a method for manufacturing a fuel cell separator will be described.
As shown in FIG. 1, the manufacturing method of the fuel cell separator 1 of the present invention includes a noble metal layer forming step S2 and a heat treatment step S3. Moreover, the manufacturing method of the separator for fuel cells of this invention may include recessed part formation process S1 before noble metal layer formation process S2.

The recess forming step S1 is a gas flow path 11 for circulating a gas such as hydrogen gas or air over at least a part of the surface of the substrate 2 as a fuel cell separator made of Ti or Ti alloy (see FIGS. 4 and 5). A recess for forming the is formed. Here, the surface of the substrate 2 refers to a surface that forms the outside of the substrate 2, and includes a so-called front surface, back surface, and side surface.
Here, the apparatus for forming the gas flow path on at least a part of the surface of the substrate 2 is not particularly limited, and a conventionally known apparatus capable of achieving a predetermined purpose can be appropriately used. .
Prior to the formation step S1, it is preferable to form the substrate 2 in a predetermined size or shape, such as a vertical width, a horizontal width, and a thickness.

  In the noble metal layer forming step S2, at least one selected from Ru, Rh, Pd, Os, Ir, Pt, and Au is formed on the surface of the substrate 2 made of Ti or Ti alloy (the entire surface of the substrate 2 or a part of the surface). A noble metal layer 3 having a thickness of 2 nm or more and containing a noble metal or more is formed by a PVD (Physical Vapor Deposition) method. Examples of the PVD method that can be used in the present invention include a sputtering method, a vacuum deposition method, and an ion plating method. Among them, the sputtering method is preferable because the thickness of the noble metal layer 3 can be easily controlled. Further, in the noble metal layer forming step S2, the noble metal layer 3 may be formed on the surface of the Ti or Ti alloy substrate in which the recesses are formed.

  Examples of the substrate 2 include 1 to 4 types of pure Ti substrates stipulated in JIS H 4600, and substrates of Ti alloys such as Ti—Al, Ti—Ta, Ti-6Al-4V, and Ti—Pd. Can do. However, the substrate 2 that can be used in the present invention is not limited to these, and even Ti alloys containing other metal elements can be suitably used.

  Noble metals such as Ru, Rh, Pd, Os, Ir, Pt and Au are excellent in corrosion resistance even though they do not form a passive film, and are excellent in conductivity because they are transition metals. It is known that these noble metal elements have properties similar to each other. Therefore, by forming the noble metal layer 3 containing a noble metal appropriately selected from these, it is possible to have good corrosion resistance and conductivity.

The thickness of the noble metal layer 3 formed in the noble metal layer forming step S2 needs to be 2 nm or more. When the thickness of the noble metal layer 3 is less than 2 nm, an excessively large number of pinholes are formed. Therefore, when heat treatment described later is performed, oxidation of Ti or Ti alloy reaches below the noble metal layer 3. The contact resistance cannot be lowered. The thickness of the noble metal layer 3 formed in the noble metal layer forming step S2 is more preferably 3 nm or more, and most preferably 5 nm or more.
The upper limit value of the thickness of the noble metal layer 3 is not particularly limited, but is preferably 500 nm or less from the viewpoint of reducing the time and cost required for forming the noble metal layer 3.

  In the noble metal layer forming step S2, the above-described noble metal noble metal layer 3 is formed by the PVD method. In the PVD method, since the noble metal layer 3 can be formed on the substrate 2 even at room temperature, not only can the damage given to the substrate 2 (for example, warpage or strength reduction) be reduced, but the noble metal layer 3 can be formed over a relatively large area. Since it can form, productivity improves.

In the noble metal layer forming step S2, the noble metal layer 3 may be formed by heating the substrate 2 to 300 to 800 ° C. Since it can transfer to heat treatment process S3 mentioned later quickly, manufacture of separator 1 for fuel cells can be made easy.
In performing the noble metal layer forming step S2, the substrate 2 can be cleaned in advance using an organic solvent such as acetone. Such cleaning is preferable because pinhole formation and poor adhesion due to contamination on the surface of the substrate 2 can be reduced.

  Next, in the heat treatment step S3, the substrate 2 on which the noble metal layer 3 is formed in the noble metal layer forming step S2 is heat-treated at a predetermined heat treatment temperature and a predetermined oxygen partial pressure to form the noble metal layer 3, and the noble metal layer At least one of a highly conductive crystallized passive film (titanium oxide layer 5 (see FIG. 2)) is formed between at least one of the substrate 3 and the substrate 2 and at a portion where the substrate 2 is exposed on the surface. Thus, the fuel cell separator 1 is manufactured.

That is, in this heat treatment step S3, a passive film (titanium oxide) crystallized in part or in whole can be formed by heat treatment under predetermined conditions.
Here, a part or all of the passive film formed on the surface of the substrate 2 before the heat treatment is crystallized by the heat treatment. During the crystallization, the passive film immediately below the noble metal layer 3 is thinned by diffusion of oxygen into the Ti base material because the supply of oxygen is blocked by the noble metal layer 3, and the oxygen oxide-deficient titanium oxide. It changes to (titanium oxide having an oxygen-deficient gradient structure). This crystallized titanium oxide becomes an n-type semiconductor whose conductivity is increased when oxygen is deficient than the stoichiometric ratio. That is, the conductivity of the passive film formed on the surface of the substrate 2 by heat treatment can be improved. Examples of such a crystal structure of titanium oxide include a rutile type crystal and a brookite type crystal. Note that the rutile crystal refers to a crystal having the same crystal structure as the rutile crystal, and the brookite crystal refers to a crystal having the same crystal structure as the brookite crystal. The oxide film 4 having such an oxygen-deficient rutile crystal and brookite crystal is more easily obtained as the oxygen partial pressure is lowered and the heat treatment is performed, such as a portion covered with the noble metal layer 3. It is even easier to obtain heat treatment under conditions with less oxygen.

  When such a heat treatment is performed, even if the passive film remains, dirt such as hydrocarbon existing on the passive film is decomposed by heat and diffused into the noble metal layer 3. It is considered that the noble metal layer 3 comes into contact with the surface of the clean passive film and / or the crystallized passive film (that is, oxygen-deficient titanium oxide) as well as a clean surface. It is considered that the consistency between the passivated film and the crystal lattice of the noble metal is improved, and the adhesion is improved.

  Therefore, the manufacturing method of the separator for a fuel cell according to the present invention can be performed when the passive film remains only by performing the heat treatment step S3 after the noble metal layer forming step S2 by the PVD method without performing complicated steps. Since part or all of the film can be a crystallized passive film (titanium oxide layer 5) having oxygen-deficient conductivity, the fuel cell has high adhesion to noble metals and low contact resistance. The separator 1 can be easily manufactured with high productivity.

The heat treatment temperature in the heat treatment step S3 is preferably 300 to 800 ° C. In order to increase the adhesion of the noble metal layer 3 and reduce the contact resistance, the passive film is crystallized, the passive film is removed, and the Ti exposed to the pinholes is oxidized to ensure the corrosion resistance of the separator. This is to make it happen.
If the heat treatment temperature is less than 300 ° C., it takes time to crystallize the passive film and remove the passive film, which is not practical. In addition, the noble metal element and Ti of the substrate 2 may not sufficiently diffuse to each other.
Further, when the heat treatment temperature exceeds 800 ° C., the diffusion is too fast, so that the noble metal element and the Ti of the substrate 2 diffuse too much, and titanium diffuses to the outermost surface of the noble metal layer 3 and oxygen in the heat treatment atmosphere. As a result, a titanium oxide layer (oxide film) containing a rutile crystal and a brookite crystal may be formed. However, since such an oxide film is formed in contact with an oxygen-containing atmosphere, it becomes an oxide film with insufficient oxygen deficiency and has higher corrosion resistance than the passive film (titanium oxide layer 5), but the contact resistance. Is unfavorable because of the high. The heat treatment temperature is more preferably 350 to 750 ° C, and most preferably 380 to 730 ° C. Even in such a temperature range, if heat treatment is performed for a long time, titanium may diffuse to the surface and an oxide film may be formed. Therefore, it is preferable to appropriately adjust the heat treatment time with respect to the heat treatment temperature.

  The heat treatment time in the heat treatment step S3 is such that the passive film existing between the noble metal layer 3 and the substrate 2 is crystallized to reduce the contact resistance (that is, improve the conductivity), or the passive film is removed or sufficiently thin. When the heat treatment time is t (min) and the heat treatment temperature is T (° C.), (420−T) / 40 ≦ t ≦ EXP ((806.4−T) / 109.2] and t ≧ 0.5.

That is, (420−T) / 40 ≦ t ≦ EXP ((806.4−T) /109.2] at 300 ≦ T ≦ 400, and 0.5 ≦ t ≦ EXP [( 806.4-T) /109.2].
FIG. 6 is a graph showing the relationship between the heat treatment time (t) and the heat treatment temperature (T). Then, as shown in FIG. 6, the present invention provides a straight line ab (t = 0.5), a straight line bc (t = (420−T) / 40), a straight line cd (T = 300), a curve de (t = Heat treatment conditions (heat treatment time (t) and heat treatment of region A (excluding T = 800) surrounded by EXP [(806.4-T) /109.2]) and straight line ea (T = 800) It is preferable to perform the heat treatment at a temperature (T).

  The heat treatment time (t) is less than (420-T) / 40 minutes (heat treatment temperature is 300 ≦ T ≦ 400 (° C.)) or less than 0.5 minutes (heat treatment temperature is 400 ≦ T <800 (° C.)). There is a possibility that crystallization of the passive film (improvement of conductivity) and removal of the passive film cannot be performed sufficiently. For this reason, not only the adhesion of the noble metal layer 3 cannot be increased, but also the contact resistance cannot be decreased.

  On the other hand, when the heat treatment time exceeds [EXP (806.4-T) /109.2] minutes (heat treatment temperature is 300 ≦ T <800 (° C.)), depending on the thickness of the noble metal layer 3, the noble metal element And Ti of the substrate 2 may diffuse excessively, and an oxide film is likely to be formed on the outermost surface. As described above, when an oxide film is formed, the contact resistance tends to increase. Further, although depending on the heat treatment temperature, the noble metal element and Ti of the substrate 2 may diffuse too much.

The oxygen partial pressure in the heat treatment step S3 is preferably set as appropriate depending on the type of noble metal used. Among the noble metals mentioned above, Pd, Ru, Rh, Os, and Ir are oxidized and the contact resistance is increased when the oxygen partial pressure is high.
In the present invention, the oxygen partial pressure is the pressure occupied by oxygen in the heat treatment furnace in which the heat treatment step S3 is performed (in the present invention, the composition of the atmosphere is that nitrogen: oxygen is approximately 4: 1). ).

More specifically, the noble metal is Ru, Rh, Pd, Os, and optionally at least one member selected from Ir, the oxygen partial pressure 1.33Pa (1 × 10 ^-2 Torr) not more than preferable.
When the oxygen partial pressure in the heat treatment step S3 is greater than ^{1.33Pa (1 × 10 -2 Torr)} , the oxygen in the atmosphere in which the heat treatment is too large, easy these noble metals is easily oxidized, contact resistance is increased . The oxygen partial pressure is preferably as low as possible, more preferably 0.665 Pa (5 × 10 ⁻³ Torr or less), and still more preferably 0.133 Pa (1 × 10 ⁻³ Torr or less).

Even under low oxygen partial pressure conditions, Ti exposed to pinholes and the like is oxidized as long as oxygen is present in the atmosphere. However, since the oxidation of Ti does not proceed excessively under low oxygen partial pressure conditions, even if there is a portion where the noble metal layer 3 is not formed on the substrate 2, an appropriate oxide film is formed in the portion. Will be.
That is, even if it is used in an acidic atmosphere, the portion where the noble metal layer 3 is formed has good conductivity, and the noble metal layer 3 has good corrosion resistance, such as pinholes. In this case, the titanium oxide layer 5 (see FIG. 2) is formed at the location where the noble metal layer 3 is not formed, so that the corrosion resistance is not deteriorated.
The heat treatment of the substrate 2 on which the noble metal layer 3 is formed by the PVD method can be performed by using a conventionally known heat treatment furnace such as an electric furnace or a gas furnace that can depressurize the inside of the furnace.

On the other hand, since Au and Pt are not oxidized, they can be heat-treated in an air atmosphere. Therefore, when the noble metal is at least one selected from Pt and Au, the oxygen partial pressure can be made equal to or lower than the oxygen partial pressure at atmospheric pressure.
As described above, when the noble metal layer forming step S2 is performed at 300 to 800 ° C., the heat treatment step S3 can be performed in a low-oxygen atmosphere chamber by simply leaving it after the PVD method is finished. Manufacturing of the fuel cell separator 1 can be facilitated.

Here, a normal product using Ti as a base material has an amorphous passive film formed on the surface thereof, and Ti in the base material is bonded to hydrogen by the passive film. It is known to prevent embrittlement. Therefore, for example, under the use conditions of about 25 ° C. and about 0.1 MPa (1 atm), the above-described passive film prevents hydrogen from being absorbed, thereby preventing Ti and hydrogen in the base material from being combined. This makes it difficult to become brittle.
However, when exposed to hydrogen at high temperature and high pressure (eg, 80 to 120 ° C., 0.2 to 0.3 MPa) like a separator for a fuel cell, the above-described passive film is amorphous. Therefore, it is difficult to sufficiently prevent hydrogen absorption, and Ti in the base material may be combined with the absorbed hydrogen to be embrittled. Further, even when the noble metal layer 3 is formed on the substrate 2 by the PVD method (sputtering method), there is a portion where the substrate 2 such as a pinhole is exposed on the surface, so that hydrogen is absorbed from the pinhole, There is a possibility that the substrate 2 is embrittled by bonding with Ti in the base material of the substrate 2.

On the other hand, in the present invention, the heat treatment at 300 to 800 ° C. is performed in the heat treatment step S3, so that the passive film between the noble metal layer 3 and the substrate 2 is crystallized or the substrate 2 exposed to the pinholes. Ti is oxidized to form a titanium oxide layer 5 (see FIG. 2) containing at least one of a rutile type crystal and a brookite type crystal. Such a titanium oxide layer 5 has an effect of blocking hydrogen absorption (simply referred to as “hydrogen absorption blocking effect”) higher than that of an amorphous passive film. Therefore, the titanium oxide layer 5 is exposed to hydrogen under high temperature and high pressure as described above. Even in such a case, Ti of the substrate 2 does not bond with hydrogen and the substrate 2 is not easily embrittled. In addition, although the above-mentioned hydrogen absorption inhibition effect can be obtained by heat treatment under a high oxygen partial pressure such as atmospheric pressure conditions, among the above-mentioned noble metals, Pd, Ru, Rh, Os, and Ir are oxygen partial pressures. If it is high, an oxide film is formed. Therefore, in order to combine the above-described hydrogen absorption preventing effect and conductivity, the oxygen partial pressure in the heat treatment step S3 of the present invention is set to 1.33 Pa (1 × 10 ⁻² Torr). It is preferable that In the case of a noble metal such as Au or Pt that is not oxidized, even if the heat treatment step S3 is performed under atmospheric pressure conditions, it is possible to have both a hydrogen absorption preventing effect and conductivity.

  Thus, even if there is a passive film between the noble metal element and the substrate 2, by conducting an appropriate heat treatment and changing the passive film to a titanium oxide layer (including crystals), conductivity, adhesion, Since both the corrosion resistance and the hydrogen absorption preventing effect can be provided, the same effect can be obtained if there is a conductive layer between the substrate 2 and the noble metal element, the corrosion resistance is high, and there is a layer that prevents hydrogen absorption. As such a layer, an oxide, nitride, carbide, oxynitride, oxycarbide, carbonitride, oxycarbonitride containing one or more elements selected from Zr, Hf, Nb, Ta, Ti, A mixture of two or more kinds selected from oxides, nitrides and carbides, a mixture of these compounds and a metal containing one or more elements selected from Zr, Hf, Nb, Ta, and Ti; A laminated body etc. are mentioned. That is, by depositing these compounds, mixtures, and laminates by a PVD method such as a sputtering method, a vacuum deposition method, an ion plating method, etc., and then forming a noble metal layer by a PVD method and performing a heat treatment, Similar effects can be obtained.

  Further, Ti or Ti alloy substrate by pickling the surface of Ti or Ti alloy substrate, forming a passive film by anodizing, forming an anodized film by anodic oxidation, or heat-treating in the atmosphere or in an atmosphere with oxygen, Ti or Ti The same effect can be obtained by forming a noble metal layer by the PVD method after the Ti oxide film is formed on the alloy surface and then performing a heat treatment.

As mentioned above, although one Embodiment of the manufacturing method of the separator for fuel cells which concerns on this invention was described, even if it is embodiment described below, it can implement suitably.
For example, a noble metal layer 3 having a thickness of 2 nm or more comprising at least one kind of noble metal selected from Ru, Rh, Pd, Os, Ir, Pt and Au on the surface of a substrate 2 made of Ti or Ti alloy. Forming a recess for forming a gas flow path through which gas flows, for example, by pressing or the like, on at least a part of the surface of the substrate 2 on which the noble metal layer 3 is formed. And a heat treatment step of heat-treating the substrate 2 on which the recess is formed at a predetermined heat treatment temperature and a predetermined partial pressure of oxygen.

  Further, for example, a noble metal having a thickness of 2 nm or more comprising at least one kind of noble metal selected from Ru, Rh, Pd, Os, Ir, Pt and Au on the surface of the substrate 2 made of Ti or Ti alloy. A noble metal layer forming step for forming the layer 3 by the PVD method, a heat treatment step for heat-treating the substrate 2 on which the noble metal layer 3 is formed under the predetermined heat treatment temperature and a predetermined oxygen partial pressure, and the surface of the heat treated substrate 2 A method of manufacturing a separator for a fuel cell may include a recess forming step for forming a recess for forming a gas flow path through which gas flows, for example, by pressing or the like at least partially.

Next, the fuel cell according to the present invention will be described with reference to the drawings as appropriate.
As shown in FIG. 5, the fuel cell 20 according to the present invention is manufactured using the above-described fuel cell separator 1 according to the present invention, and can be manufactured as follows.
For example, a predetermined number of substrates 2 made of Ti or Ti alloy is prepared, and the predetermined number of substrates 2 is set to a predetermined size of 95.2 mm in length × 95.2 mm in width × 19 mm in thickness, and For example, a recess having a groove width of 0.6 mm and a groove depth of 0.5 mm is formed in the center portion of the surface by machining or etching to form a gas flow path 11 having a shape as shown in FIG.

  Then, after ultrasonically cleaning the substrate 2 in which the recesses are formed with an organic solvent such as acetone, the substrate 2 is set in a chamber of an apparatus for performing a PVD method such as a sputtering apparatus, for example. Then, the inside of the chamber is evacuated, and after introducing argon gas, a voltage is applied to a noble metal target (for example, Au) to excite the argon gas to generate plasma, and an Au noble metal layer 3 is formed on the substrate 2. Form. The substrate 2 on which the noble metal layer 3 is formed in this manner is put in a heat treatment furnace, pulled to a predetermined degree of vacuum, and then subjected to a heat treatment that is heated at 500 ° C. for 5 minutes to produce a predetermined number of fuel cell separators 1.

  Note that productivity can be improved by preparing a large number of substrates 2 in advance and collectively forming the noble metal layer 3 and performing heat treatment. In addition, according to the present invention, it is not necessary to physically remove the passive film with an argon ion beam or the like before forming the noble metal layer 3 as in a conventionally known method. improves. In particular, in the case of Au or Pt, it is not necessary to draw a vacuum, and heat treatment can be performed with an oxygen partial pressure at atmospheric pressure, so that productivity can be further improved.

  Next, as shown in FIG. 5, for example, two fuel cell separators 1 that are manufactured in a predetermined number are disposed so that the surfaces on which the gas flow paths 11 are formed face each other, and the gas flow paths 11 are formed. A gas diffusion layer 12 such as carbon cloth C for uniformly diffusing the gas on the film is disposed on each surface, and a platinum catalyst is placed on the surface between one gas diffusion layer 12 and the other gas diffusion layer 12. The single cell 10 is produced with the solid polymer film 13 applied therebetween. In the same manner, a plurality of single cells 10 created in a similar manner are stacked to form a cell stack (not shown), and other components necessary for the fuel cell are attached and connected to provide good corrosion resistance and conductivity. The fuel cell (solid polymer fuel cell) 20 according to the present invention can be produced. Further, as described above, if the fuel cell 20 can supply gas from the fuel cell separator 1 to the solid polymer film 13 via the gas diffusion layer 12, the gas flow is generated on the surface of the substrate 2 (fuel cell separator 1). It is not necessary to form a recess for forming the path 11.

  The solid polymer membrane 13 used in the fuel cell 20 can be used without particular limitation as long as it has a function of moving protons generated at the cathode electrode to the anode electrode. A fluorine-based polymer film having a group can be preferably used.

  The fuel cell 20 thus manufactured introduces fuel gas (for example, hydrogen gas with a purity of 99.999%) into the fuel cell separator 1 arranged as an anode electrode through the gas flow path 11. Air is introduced into the fuel cell separator 1 arranged as the cathode electrode through the gas flow path 11. At this time, the fuel cell 20 is preferably heated and kept at about 80 ° C., and the dew point temperature is preferably adjusted to 80 ° C. by passing the hydrogen gas and air through the heated water. The fuel gas (hydrogen gas) and air may be introduced at a pressure of 2026 hPa (2 atm), for example.

The fuel cell 20 is uniformly supplied to the solid polymer film 13 by the gas diffusion layer 12 by introducing hydrogen gas into the anode electrode in this way, and the solid polymer film 13 uses the following formula (1). Reaction occurs.
_{^{H 2 → 2H + + 2e -}} ··· (1)
On the other hand, the fuel cell 20 is uniformly supplied to the solid polymer film 13 by the gas diffusion layer 12 by introducing air into the cathode electrode, and the reaction of the following formula (2) is performed in the solid polymer film 13. Arise.
_{^{4H + + O 2 + 4e -}} → H 2 O ··· (2)
As described above, the reaction of the above formulas (1) and (2) occurs in the solid polymer film 13, so that a voltage of about 1.2V is theoretically obtained.

  Here, as described above, since the fuel cell 20 according to the present invention uses the fuel cell separator 1 according to the present invention in which at least the noble metal layer 3 is formed, the fuel using the conventional metal separator is used. It becomes possible to have good corrosion resistance and conductivity as compared with the battery.

Next, the fuel cell separator manufacturing method, fuel cell separator, and fuel cell of the present invention will be described in detail by comparing an example that satisfies the requirements of the present invention with a comparative example that does not satisfy the requirements of the present invention. To do.
<Example A>
Two substrates (width 2cm x 5cm, thickness 1mm) made of Ti-6Al-4V alloy were ultrasonically cleaned with acetone, and then mounted on a substrate stand in a chamber of a magnetron sputtering apparatus which is an apparatus for performing the PVD method. It was. Then, Au and Pt were attached to the electrodes in the chamber as noble metal targets, and then the inside of the chamber was evacuated to a vacuum of 0.00133 Pa (1 × 10 ⁻⁵ Torr) or less.
Argon gas was introduced into the chamber and the pressure was adjusted to 0.266 Pa (2 × 10 ⁻³ Torr). Thereafter, RF (radio frequency) is applied to an electrode on which Au and Pt, which are noble metal targets, are attached to excite argon gas, and argon plasma is generated to perform sputtering of Au and Pt. Pt noble metal layers (hereinafter referred to as “noble metal layers (Au and Pt)”) were formed with thicknesses of 10 nm and 30 nm, respectively. Further, the Ti alloy substrate was turned upside down, and a noble metal layer (Au and Pt) having the same thickness was formed on the other surface of the substrate by the same method.
Thereafter, the Ti-6Al-4V alloy plate on which the noble metal layer is formed is placed in a heat treatment furnace heated to 500 ° C. under atmospheric pressure, heat treated for 1 minute, and the furnace is cooled to 100 ° C. A test plate (corresponding to a fuel cell separator) on which a noble metal layer (Au and Pt) is formed is taken out, and a test plate 1 and 3 on which a noble metal layer (Au) is formed and a noble metal layer (Pt) are formed Were used as test plates 2 and 4.

(1) About these test plates 1-4, the contact resistance before and behind heat processing was measured with the load 98N (10 kgf) using the contact resistance measuring apparatus 30 shown in FIG. That is, for each of the test plates 1 to 4, both surfaces thereof are sandwiched with Au foil (corresponding to carbon cloth C and C in FIG. 3), and the outside is further used with copper electrodes 31 and 31 having a contact area of 1 cm ^2. A pressure of 98 N was applied, 7.4 mA electricity was applied using the direct current power source 32, the voltage applied between the Au foils was measured with the voltmeter 33, and the contact resistance was calculated.
(2) Further, each of the test plates 1 to 4 was immersed in an aqueous sulfuric acid solution (pH 2) at 80 ° C. for 1000 hours, and then contact resistance was measured again in the same manner as described above. The contact resistance after the heat treatment and (2) (1) was evaluated as acceptable 0.5mΩ · cm ² or less.
(3) Further, the adhesion test of the noble metal layers (Au and Pt) before and after the heat treatment was evaluated by a cross-cut tape peeling test. The cross-cut tape peel test was performed in accordance with the method described in the plating adhesion test method defined in JIS H8504.
Table 1 shows the results of (1) contact resistance before and after heat treatment, (2) contact resistance after being immersed in an aqueous sulfuric acid solution (pH 2) at 80 ° C. for 1000 hours, and (3) cross-cut tape peeling test.

  Further, in order to examine the interface structure between the noble metal thin film and the Ti-6Al-4V substrate, the cross section of the test plate 1 was observed with a transmission electron microscope (TEM). The TEM observation conditions were a sample thickness of about 100 nm, an acceleration voltage of 200 kV, and a magnification of 1.5 million times.

Furthermore, using a Ti substrate made of one kind of pure Ti as defined in JIS H 4600 as a substrate and Pd as a noble metal target, the thickness of the noble metal layer (Pd) is 1 nm by the PVD method similar to the above. The formed substrate was produced. Next, the substrate on which the noble metal layer is formed is placed in a heat treatment furnace, the inside of the furnace is evacuated to 0.133 Pa (1 × 10 ⁻³ Torr), and after heat treatment is performed at 500 ° C. for 15 minutes, When the temperature reached 100 ° C., the test plate 5 on which the noble metal layer (Pd) was formed was taken out. The test plate 5 was subjected to contact resistance measurement and a cross-cut tape peeling test in the same manner as the test plates 1 to 4, and the results are shown in Table 1.

  From the results shown in Table 1, it was found that in the test plates 1 to 4, the contact resistance was lowered and the adhesion was improved by heat treatment under oxygen partial pressure under atmospheric pressure. Furthermore, even after being immersed in an aqueous sulfuric acid solution (pH 2) at 80 ° C. for 1000 hours, no increase in contact resistance was observed, indicating that the corrosion resistance was also excellent. Moreover, from the result of observation by TEM, it was confirmed that there was a titanium oxide layer having a thickness of about 5 nm between the noble metal layer (Au) and the substrate. Furthermore, when the crystal structure of the titanium oxide layer was examined by electron diffraction (nano-diffraction) performed with the beam diameter reduced to about 1 nm, it was found that rutile crystals were included.

  On the other hand, the test plate 5 having a thickness of 1 nm of the noble metal layer (Pd) is a cross-cut tape peeling test performed after the heat treatment, but there is no peeling after the heat treatment, and the adhesion between the noble metal layer and the substrate is high. It was found that there was little decrease in contact resistance due to heat treatment and the conductivity was inferior. In addition, it was found that the contact resistance after 1000 hours of immersion in an aqueous sulfuric acid solution (pH 2) at 80 ° C. greatly increased and the corrosion resistance was poor (Comparative Example).

<Example B>
A noble metal layer having a thickness of 5 nm was formed on a Ti-5Ta substrate by vacuum deposition of various noble metals shown in Table 2.
A noble metal is put in a crucible (carbon crucible) of a chamber of a vacuum deposition apparatus that performs vacuum deposition, and a Ti-5Ta substrate is set above the chamber, and the inside of the chamber is 0.000133 Pa (1 × 10 ⁻⁶ Torr). The precious metal was dissolved and evaporated by irradiating the precious metal in the crucible with an electron beam under conditions of an acceleration voltage of 5 kV and an emission current of 50 mA to form a precious metal layer on the Ti-5Ta substrate. The thickness of the noble metal layer was measured by a change in the frequency of the quartz oscillator film thickness meter, and the formation of the noble metal layer was completed when the thickness reached 5 nm. Thereafter, a noble metal layer was also formed on both sides by similarly forming a noble metal layer on the back side.
Thereafter, a substrate made of Ti-5Ta having a noble metal layer formed therein is put in a heat treatment furnace, evacuated to 0.00133 Pa (1 × 10 ⁻⁵ Torr), and heated to a predetermined temperature shown in Table 2, Test plates 6 to 14 were manufactured by introducing oxygen while evacuating the furnace so that the predetermined oxygen partial pressure shown in Table 2 was obtained, and performing heat treatment.

Using these test plates 6 to 14, (1) contact resistance before and after heat treatment was measured. The contact resistance was measured according to <Example A>. In <Example B>, measurement was performed using a carbon cloth.
(2) Furthermore, after immersing each of the test plates 6 to 14 in an aqueous sulfuric acid solution (pH 2) at 80 ° C. for 1000 hours, the contact resistance was measured again in the same manner as described above. In addition, after the heat treatment of (1) and the contact resistance of (2), 12 mΩ · cm ² or less was accepted.
Table 2 shows the results of (1) contact resistance before and after heat treatment, and (2) contact resistance after dipping in an aqueous sulfuric acid solution (pH 2) at 80 ° C. for 1000 hours.

From the results shown in Table 2, among the test plates 6 to 11 in which the oxygen partial pressure was 1.33 Pa (1 × 10 ⁻² Torr) or less and heat treatment was performed at 300 ° C. to 800 ° C., the test plates 6 to 10 were It has been found that low contact resistance can be obtained.

On the other hand, because the processing time of test plate 11 was too long, the diffusion layer of Pd and Ti grew too much, and Ti diffused to the outermost surface to form titanium oxide on the outermost surface, so that the contact resistance was low. It did not drop.
In the test plate 12, since the oxygen partial pressure was high, Pd was oxidized and the contact resistance did not decrease.
In the test plate 13, since the heat treatment temperature is high, the diffusion layer of Au and Ti grows too much, and Ti diffuses to the outermost surface and titanium oxide is formed on the outermost surface, so the contact resistance does not decrease. .
Since the test plate 14 had a low heat treatment temperature, the passive film could not be crystallized, and the thickness was hardly changed, so there was almost no decrease in contact resistance, although the contact resistance after immersion in sulfuric acid was low. In addition, circular peeling with a diameter of about 1 mm was observed.

<Example C>
First, eight Ti substrates (width 2 cm × 5 cm, thickness 0.2 mm) made of one kind of pure Ti specified in JIS H 4600 were prepared. By performing the PVD method (sputtering method) on the surface of these Ti substrates under the same conditions as described in <Example A>, a noble metal layer of Au and Pt is formed with a thickness of 10 nm on each Ti substrate. (Test plates 15 to 22).
Thereafter, 500 ° C. The test plates 16, 20 forming a noble metal layer under conditions atmospheric pressure (oxygen partial pressure 2.13 × 10 ⁴ Pa), heat treatment was performed under conditions of 1 minute.

Further, the test plates 17, 18, 21, and 22 on which the noble metal layer is formed are put into a vacuum heat treatment furnace, the pressure in the furnace is evacuated to 0.00133 Pa (1 × 10 ⁻⁵ Torr), and then heated to 500 ° C. As shown in Table 4 below, the oxygen partial pressure in the furnace is 0.133 Pa (1 × 10 ⁻³ Torr) or 0.00133 Pa (1 × 10 ⁻⁵ Torr) by introducing dry air. Then, heat treatment was performed at 500 ° C. for 5 minutes under such partial pressure of oxygen.
For comparison with the test plates 16 to 18 and 20 to 22, the two Ti substrates of the test plates 15 and 19 were formed with a noble metal layer of Au and Pt with a thickness of 10 nm, and then heat treatment shown in Table 3 No heat treatment was performed under the conditions.

The contact resistance of the test plates 15 to 22 described above was measured and calculated under the same conditions as described in <Example A>.
Moreover, these test plates 15-22 are put into the gas phase part of the airtight container containing water and 0.3 MPa (3 atm) hydrogen, and this is heated at 120 degreeC, and it becomes about 100% of humidity. After exposure for 500 hours in a humidified pure hydrogen (purity 99.99%) atmosphere (hereinafter simply referred to as “humidified pure hydrogen atmosphere”), it is placed in a graphite crucible in an inert gas (Ar) stream. The sample is heated and melted together with tin by the graphite resistance heating method, hydrogen is extracted together with other gases, the extracted gas is passed through a separation column to separate hydrogen from other gases, and the separated hydrogen is detected for thermal conductivity. The hydrogen concentration (ppm) in the test plates 15 to 22 was measured by conveying to a vessel and measuring the change in thermal conductivity due to hydrogen (inert gas melting-gas chromatograph method).
The contact resistance and the hydrogen concentration in the test plates 15 to 22 (shown as “hydrogen concentration in the test plate” in Table 4) are shown in Table 3 below together with the heat treatment conditions described above. The contact resistance was as acceptable 0.5mΩ · cm ² or less, the concentration of hydrogen in the Ti substrate was passed below 70 ppm.

Here, the concentration of hydrogen contained in one kind of pure Ti material specified in JIS H 4600 is usually about 20 to 40 ppm.
As shown in Table 3, the test plates 15 and 19 that were not heat-treated under the heat treatment conditions shown in Table 3 had a slightly high contact resistance, and the hydrogen concentration in the test plate was also a high value. That is, good results could not be obtained. Since the hydrogen concentration in the test plate was a high value, it was found that hydrogen was absorbed into the base material of the Ti substrate by exposure to a humidified pure hydrogen atmosphere for 500 hours.
Moreover, as shown in Table 3, the test plates 16 to 18 and 20 to 22 subjected to the heat treatment under the heat treatment conditions shown in Table 3 have low contact resistance, and the hydrogen concentration in the test plate is also low. became. That is, good results could be obtained.

  From the results of <Example C>, the test plates 16 to 18 and 20 to 22 were able to reduce the contact resistance by heat treatment and were exposed to a humidified pure hydrogen atmosphere for 500 hours. It was also confirmed that hydrogen was not absorbed.

<Example D>
A chamber of a magnetron sputtering apparatus which is an apparatus for performing a PVD method after ultrasonically cleaning a Ti substrate (width 2 cm × 5 cm, thickness 1 mm) made of one kind of pure Ti specified in JIS H 4600 with acetone. It was attached to the substrate board inside. And after attaching Au to the electrode in a chamber as a noble metal target, the inside of the chamber was evacuated to a vacuum of 0.00133 Pa (1 × 10 ⁻⁵ Torr) or less.

Argon gas was introduced into the chamber, the pressure was adjusted to ^{0.266Pa (2 × 10 -3 Torr)} . Thereafter, a DC (direct current) voltage is applied to an electrode on which Au, which is a noble metal target, is attached to excite argon gas, and argon plasma is generated to perform sputtering of Au. Hereinafter, a “noble metal layer (Au)”) was formed to a thickness of 20 nm. Further, the titanium substrate was turned over, and a noble metal layer (Au) having a thickness of 20 nm was formed on the other surface of the substrate by the same method.

Thereafter, a Ti substrate on which a noble metal layer (Au) is formed is placed in a heat treatment furnace, evacuated to 0.00133 Pa (1 × 10 ⁻⁵ Torr), and heated to a predetermined temperature shown in Table 5 Then, heat treatment was performed by introducing oxygen while exhausting the inside of the furnace so that the oxygen partial pressure was 0.00665 Pa (5 × 10 ⁻⁵ Torr), and the test plates 23 to 35 were manufactured.

Using these test plates 23 to 35, (1) contact resistance before and after heat treatment was measured. The contact resistance was measured according to <Example A>.
(2) Furthermore, after immersing each of the test plates 23 to 35 in an 80 ° C. sulfuric acid aqueous solution (pH 2) for 1000 hours, the contact resistance was measured again in the same manner as described above. In addition, after the heat treatment of (1) and the contact resistance of (2), 0.5 mΩ · cm ² or less was accepted.
Table 4 shows the results of (1) contact resistance before and after heat treatment, and (2) contact resistance after being immersed in an aqueous sulfuric acid solution (pH 2) at 80 ° C. for 1000 hours.

  From the results shown in Table 4, when the heat treatment time is t (minutes) and the heat treatment temperature is T (° C.), the test plates 23 to 29 are (420−T) / 40 ≦ t ≦ EXP [(806.4−T ) /109.2] and t ≧ 0.5 (300 ≦ T <800), it was found that low contact resistance was obtained because the heat treatment was performed.

On the other hand, the test plates 30 and 31 did not satisfy (420−T) / 40 ≦ t, and the processing time was too short. The test plate 32 did not satisfy t ≧ 0.5, and the processing time was too short. Therefore, the test plates 30 to 32 were insufficient to crystallize the passive film existing between Au and the substrate to improve the conductivity, and the contact resistance did not decrease.
In the test plates 33 to 35, since the processing time was too long, the diffusion layer of Au and Ti grew too much, Ti diffused to the outermost surface and titanium oxide was formed on the outermost surface, and the contact resistance decreased. There wasn't.

<Example E>
Next, in <Example E>, a power generation test was performed in the case where a separator manufactured using the Ti alloy substrate of the test plate 1 described above was used.
First, two Ti alloy substrates having a size of 95.2 mm in length, 95.2 mm in width, and 19 mm in thickness are prepared, and the center of the surface is machined to have a groove width of 0.6 mm and a groove depth of 0.5 mm. The gas flow path was produced in the shape shown in FIG. Then, on the surface of the Ti alloy substrate on which the gas flow path was formed, a separator was prepared by performing Au film formation and heat treatment under the same method and conditions as in <Example A>.

Then, the produced separator was incorporated into a solid polymer fuel cell (manufactured by Electrochem, fuel cell EFC-05-01SP) as follows, and a power generation test was performed.
First, as shown in FIG. 5, the two separators prepared were placed with the surfaces on which the gas flow paths were formed facing each other, and the carbon cloth was placed on each surface on which the gas flow paths were formed. A fuel cell for power generation test was fabricated by sandwiching a solid polymer film between the carbon cloths.

Hydrogen gas having a purity of 99.999% was used as the fuel gas introduced into the anode electrode side of the fuel cell produced as described above, and air was used as the gas introduced into the cathode electrode side.
The fuel cell is heated and kept at 80 ° C., and the dew point temperature is adjusted to 80 ° C. by passing hydrogen gas and air through heated water, and the fuel cell is operated at a pressure of 2026 hPa (2 atm). Introduced.

Then, using a cell performance measurement system (890CL manufactured by Scribner), the current flowing through the separator was set to 300 mA / cm ² and power was generated for 100 hours to measure the change in voltage.
As a result, the initial voltage of the separator of the Ti substrate of the test plate 7 and the voltage after 100 hours of power generation were both 0.61 V, and no change in voltage was observed.

In addition, as a comparison object, instead of the Ti alloy substrate separator of the test plate 1, a fuel cell was manufactured by arranging a conventional graphite separator (manufactured by Electrochem, FC-05MP), under the same conditions as above. A power generation test was conducted.
As a result, the voltage at the initial stage of power generation and the voltage after power generation for 100 hours were both 0.61 V, and the result was exactly the same as that of the separator of the Ti alloy substrate of the test plate 1.

  From the above results, it has been found that the fuel cell separator produced by the method for producing a fuel cell separator of the present invention exhibits the same performance as a graphite separator even though it is a metallic separator.

  The fuel cell separator manufacturing method, the fuel cell separator and the fuel cell according to the present invention have been described in detail with reference to the preferred embodiments and examples. However, the gist of the present invention is limited to the contents described above. The scope of rights should be broadly interpreted based on the claims. Needless to say, the contents of the present invention can be widely modified and changed based on the above description.

S1 Concave formation step S2 Noble metal layer formation step S3 Heat treatment step 1 Fuel cell separator 2 Substrate 3 Noble metal layer 5 Titanium oxide layer 10 Single cell 11 Gas flow path 12 Gas diffusion layer 13 Solid polymer membrane 20 Fuel cell

Claims (3)

  A noble metal layer having a thickness of 2 nm or more comprising at least one kind of noble metal selected from Ru, Rh, Pd, Os, Ir, Pt and Au is formed on the surface of a substrate made of Ti or Ti alloy, In addition, a titanium oxide layer containing at least one of a rutile crystal and a brookite crystal is formed between at least one of the noble metal layer and the substrate and a portion where the substrate is exposed on the surface. Fuel cell separator.   The substrate is formed with a recess for forming a gas flow path for allowing a gas to flow through at least a part of the surface of the substrate, and the noble metal layer is formed on the surface of the substrate on which the recess is formed. The fuel cell separator according to claim 1.   A fuel cell comprising the fuel cell separator according to claim 1.

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