JP2008108685A - Manufacturing method of fuel cell separator, fuel cell separator, and fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a fuel cell separator capable of maintaining contact resistance low and stable over a long period. <P>SOLUTION: The manufacturing method of the separator for the fuel cell includes a formation process S1 in which recesses in order to form a gas flow passage 11 to make gas circulate are formed at least at one part of the surface of a substrate 2 as the fuel cell separator formed of Ti or a Ti alloy, an adhesion process S2 in which the substrate 2 on which the recesses are formed is impregnated into an acid solution containing at least one or more kinds of noble metals selected from Ru, Rh, Pd, Os, Ir, Pt, and Au, and noble metal particles are precipitated and adhered to the surface of the substrate 2, and a heat treatment process S3 in which by heat treating the substrate 2 to which the particles are adhered, island-form crystals 3 containing the noble metals are formed on the surface of the substrate 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a separator for 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, etc. The present invention relates to a battery separator and a fuel cell.

  A polymer electrolyte fuel cell (hereinafter simply referred to as a “fuel cell”) has a solid polymer electrolyte membrane sandwiched between an anode electrode and a cathode electrode as a single cell, and is connected to an electrode called a separator or a bipolar plate. Thus, a plurality of the aforementioned single cells are overlapped.

  This fuel cell separator (hereinafter simply referred to as “separator”) has low contact resistance, and can maintain low contact resistance over a long period of time during which it is processed and used as a separator. Required. In addition, in consideration of workability and strength, it has been conventionally studied to apply metal materials such as aluminum (Al) alloy, stainless steel (SUS), nickel (Ni) alloy, titanium (Ti) alloy and the like. Yes.

In addition, as a result of diligent research on separators, several techniques have been proposed for ensuring good electrical conductivity by suppressing an increase in contact resistance.
For example, Patent Document 1 proposes a technique for forming a gold plating layer on the surface of a metal separator such as SUS or Ti alloy. For example, Patent Document 2 discloses a technique made of metal such as SUS or Ti alloy. A technique for adhering a noble metal or noble metal alloy film (noble metal film) to the surface of the separator has been proposed.

JP-A-10-228914 JP 2001-6713 A

  However, these separators, which have been studied for application in the past, have a problem that, as they are used, an oxide film or the like is formed on the surface thereof, so that the contact resistance increases and the conductivity is significantly deteriorated. was there. Therefore, it has been difficult for these separators to maintain good conductivity over a long period of time.

  Moreover, since the technique described in Patent Document 1 does not include a step of removing the passive film in the process of manufacturing the separator, the adhesion of the gold plating layer is deteriorated, and the contact resistance is increased by the passive film. is there.

  In addition, the technique described in Patent Document 2 uses a corrosion reaction to deposit platinum (Pt), which is a noble metal, while mechanically polishing the surface of a SUS or Ti alloy substrate in order to remove the passive film. Processing to form a layer is performed. When such treatment is performed, Pt is deposited on the portion where the passive film has been removed, so that the contact resistance is reduced (that is, the conductivity is improved), but the pinhole (where the substrate partially appears on the surface) SUS and Ti are eluted from the pinhole when used in an acidic atmosphere such as a fuel cell because the uniform and dense noble metal layer is not formed. There is a disadvantage that it deteriorates. In addition, there is a drawback that the operation for removing the passive film is complicated.

  An object of the present invention is to provide a method for manufacturing a fuel cell separator capable of manufacturing a fuel cell separator capable of stably maintaining a low contact resistance over a long period of time. An object of the present invention is to provide a fuel cell separator and a fuel cell using the fuel cell separator.

  In order to solve the above-described problems, a method for manufacturing a fuel cell separator according to the present invention forms a gas flow path for flowing gas over at least a part of the surface of a substrate as a fuel cell separator made of Ti or Ti alloy. Forming a recess for forming the substrate, and forming a substrate on which the recess is formed in an acid solution containing at least one kind of noble metal ions selected from Ru, Rh, Pd, Os, Ir, Pt and Au. An adhesion step of immersing and precipitating the particles of the noble metal on the surface of the substrate, and an island-like crystal containing the noble metal on the surface of the substrate by heat-treating the substrate to which the particles are adhered And a heat treatment step for forming the film.

  As described above, the manufacturing method of the fuel cell separator according to the present invention performs the adhering step after forming the recess for forming the gas flow path through which the gas flows in the forming step without performing a complicated step. Thus, it is possible to easily attach the noble metal particles to the surface of the substrate simply by placing the substrate on an acid solution containing noble metal ions. Then, by simply performing a heat treatment step after the attaching step, the noble metal particles attached to the surface can be aggregated to form island-like crystals, and further, the substrate and the island-like crystals can be integrated. Therefore, high conductivity can be obtained. Accordingly, the contact resistance can be kept low and stable over a long period of time. Further, since the oxide film is formed by heat treatment in the portion where noble metal particles are not adhered, Ti of the substrate does not elute even when used in an acidic atmosphere. Therefore, a fuel cell separator that does not deteriorate the power generation characteristics of the fuel cell can be manufactured.

In the method for producing a fuel cell separator according to the present invention, the heat treatment temperature in the heat treatment step is preferably 300 to 800 ° C.
As described above, the method for manufacturing a separator for a fuel cell according to the present invention forms island-shaped crystals containing a noble metal with an appropriate size by limiting the temperature of the heat treatment in the heat treatment step to a specific range. In addition, it is possible to diffuse the noble metal element and Ti mutually and appropriately.

In the method for producing a fuel cell separator according to the present invention, the oxygen partial pressure in the heat treatment step is preferably 0.133 Pa (1 × 10 ⁻³ Torr) or less.
Thus, the fuel cell separator manufacturing method of the present invention reduces the amount of Ti oxide produced, that is, the thickness of the oxide film, by limiting the oxygen partial pressure in the heat treatment process to a specific range. Can be planned.

In order to solve the above-mentioned problems, a fuel cell separator according to the present invention is for a fuel cell made of Ti or Ti alloy in which a recess for forming a gas flow path for allowing a gas to flow through at least a part of the surface is formed. The substrate as a separator is immersed in an acid solution containing ions of at least one kind of noble metal selected from Ru, Rh, Pd, Os, Ir, Pt, and Au, and the substrate immersed in the acid solution is heat treated. It is characterized by having been obtained.
As described above, the fuel cell separator of the present invention includes a noble metal for maintaining a low and stable contact resistance over a long period of time by being immersed in an acid solution containing noble metal ions and heat-treated. An island-like crystal is formed.

In the fuel cell separator according to the present invention, the heat treatment temperature is preferably 300 to 800 ° C.
In this way, by limiting the temperature of the heat treatment to a specific range, it is possible to form island-like crystals containing noble metals with an appropriate size and to diffuse the noble metal elements and Ti mutually and appropriately. Can be made.

The fuel cell separator according to the present invention preferably has an oxygen partial pressure in the heat treatment of 0.133 Pa (1 × 10 ⁻³ Torr) or less.
Thus, by limiting the oxygen partial pressure to a specific range, it is possible to reduce the amount of Ti oxide produced, that is, to reduce the thickness of the passive film.

The fuel cell separator according to the present invention is formed on the surface of a substrate as a fuel cell separator made of Ti or Ti alloy in which a recess for forming a gas flow path for allowing gas to flow through at least a part of the surface is formed. Having an island-shaped crystal containing at least one or more kinds of noble metals selected from Ru, Rh, Pd, Os, Ir, Pt, and Au, and between the island-shaped crystal and the substrate, It has a diffusion layer in which a noble metal element and Ti of the substrate diffuse each other.
Since the separator for a fuel cell of the present invention has such a diffusion layer, the electrical resistance (contact resistance) between the substrate and the island-like crystal can be prevented from becoming high. Further, by having such a diffusion layer, it is possible to increase the bonding force for bonding the island-shaped crystal and the substrate, so that the adhesion between the island-shaped crystal and the substrate can be improved.

In the fuel cell separator according to the present invention, the portion where the island-like crystals are not formed on the surface of the substrate forms an oxide film in which Ti on the surface of the substrate is oxidized during the heat treatment step. Is preferred.
As described above, the fuel cell separator according to the present invention has excellent conductivity and corrosion resistance because the island-shaped crystal containing the specific noble metal is formed on the surface of the substrate. And since the oxide film is formed in the surface of a board | substrate, a pinhole etc. are not formed. Therefore, even when used in an acidic atmosphere such as a fuel cell, Ti does not elute from the pinhole, and the power generation characteristics of the fuel cell do not deteriorate.

In the fuel cell separator according to the present invention, the amount of the noble metal that forms the island-shaped crystal when the surface of the substrate on which the island-shaped crystal is formed is measured by SEM / EDX analysis is 0.1 at% or more. Is preferred.
The fuel cell separator of the present invention can reliably reduce the contact resistance by regulating the amount of the noble metal to a certain value or more when the surface is measured by SEM / EDX analysis.

  The separator for a fuel cell according to the present invention has a Ru, Rh, Pd, or the like formed on the surface of a substrate made of Ti or Ti alloy in which a recess for forming a gas flow path through which gas flows is provided on at least a part of the surface. An island-shaped crystal containing at least one kind of noble metal selected from Os, Ir, Pt and Au is formed, and a rutile-type crystal and a brookite-type crystal are formed between the island-shaped crystal and the substrate. A titanium oxide layer containing at least one is 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 the island-like crystal and the substrate, so that the contact resistance is further reduced. Can do. That is, conductivity can be improved.

  The fuel cell of the present invention preferably uses the fuel cell separator described above. Since the fuel cell separator of the present invention uses the above-described fuel cell separator, the contact resistance can be maintained stably over a long period of time.

The method for producing a fuel cell separator according to the present invention can produce a fuel cell separator capable of maintaining a low contact resistance over a long period of time and stably. In particular, in the method for producing a fuel cell separator according to the present invention, since only the adhesion step and the heat treatment step are performed, the fuel cell separator can be produced by a simple operation.
In addition, the fuel cell separator according to the present invention has a low contact resistance over a long period of time and can be stably maintained.
In addition, the fuel cell according to the present invention has a low contact resistance over a long period of time and can be stably maintained.

Next, the best mode for carrying out the method for manufacturing a fuel cell separator, the fuel cell separator and the fuel cell according to the present invention will be described with reference to the drawings as appropriate. In the drawings to be referred to, FIG. 1 is a flowchart for explaining the steps of the method for manufacturing a fuel cell separator according to the present invention. FIGS. 2A and 2B are cross-sectional views of a fuel cell separator according to the present invention. FIG. 3 is an explanatory diagram for explaining a method of measuring contact resistance. FIG. 4 is a diagram showing an example of the shape of the gas flow path formed on the surface of the substrate. FIG. 5 is a diagram showing a state in which a part of a fuel cell using the fuel cell separator of the present invention is developed.
In the drawings to be referred to, reference numeral S1 indicates a forming process, reference numeral S2 indicates an adhesion process, reference numeral S3 indicates a heat treatment process, reference numeral 1 indicates a fuel cell separator, and reference numeral 2 indicates a substrate. Reference numeral 3 indicates an island-shaped crystal, reference numeral 4 indicates an oxide film, reference numeral 5 indicates a diffusion layer, reference numeral 10 indicates a single cell, and reference numeral 11 indicates a gas flow path. Reference numeral 12 denotes a gas diffusion layer, reference numeral 13 denotes a solid polymer film, and reference numeral 20 denotes a fuel cell.

First, the manufacturing method of the separator for fuel cells of this invention is demonstrated.
As shown in FIG. 1, the manufacturing method of the separator 1 for fuel cells of this invention comprises formation process S1, adhesion process S2, and heat treatment process S3.

In the forming step S1, a gas flow path 11 (see FIGS. 4 and 5) for circulating a gas such as hydrogen gas or air is provided on at least a part of the surface of the substrate 2 as a fuel cell separator made of Ti or Ti alloy. A recess for forming 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 attaching step S2, the substrate 2 made of Ti or Ti alloy having a recess is immersed in an acid solution containing at least one kind of ions selected from Ru, Rh, Pd, Os, Ir, Pt and Au. Then, the above-mentioned noble metal particles are deposited on the surface of the substrate 2 and attached.

  As the substrate 2, 1 to 4 types of pure Ti substrates as defined in JIS H 4600, and Ti alloy substrates such as Ti-Al, Ti-Ta, Ti-6Al-4V, Ti-Pd, and α alloys are used. Can be mentioned. 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 and the like 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 using a noble metal appropriately selected from these, it is possible to have good corrosion resistance and conductivity.
In addition, it cannot be overemphasized that this noble metal may be used by 1 type, and can mix and use 2 or more types.

  As a suitable technique for attaching the above-mentioned noble metal particles to the surface of the substrate 2, for example, a noble metal formed by immersing in an acid solution containing noble metal ions such as displacement plating and depositing noble metal ions. A method of adhering the particles to the surface of the substrate 2 can be mentioned.

As the acid solution used in this case, for example, a mixed acid aqueous solution of hydrofluoric acid and nitric acid is preferably used.
In the mixed acid aqueous solution of hydrofluoric acid and nitric acid, hydrofluoric acid and nitric acid are preferably mixed at a ratio of 1: 2 to 1:20.
The concentration of hydrofluoric acid is preferably 0.005 to 0.5%, and the concentration of nitric acid is preferably 0.01 to 10%.
With such a mixing ratio and concentration, it is possible to suitably retain the ability to dissolve the material that contains the noble metal ions and serves as the base material.
In the present invention, the solution is not limited to this as long as it contains the above-mentioned noble metal ions and has the ability to dissolve the material to be the base material. An acid solution such as an acid solution, a formic acid solution, or an oxalic acid solution can also be used.

  Here, the concentration of the noble metal contained in the acid solution is preferably 10 to 50 ppm. If the concentration of the noble metal contained in the acid solution is less than 10 ppm, the amount of noble metal ions produced is small, and therefore the amount of noble metal ions that precipitate and adhere to the surface of the substrate 2 as noble metal particles also decreases. Therefore, there is a possibility that the contact resistance cannot be sufficiently reduced. On the other hand, if the concentration of the noble metal contained in the acid solution exceeds 50 ppm, it is not preferable from the viewpoint of cost.

  Next, in the heat treatment step S3, the substrate 2 to which the above-mentioned noble metal particles are adhered is heat-treated to form island-like crystals 3 containing the noble metal, and the fuel cell separator 1 is manufactured. By heat treatment, the noble metal particles adhered to the surface of the substrate 2 are aggregated, that is, the noble metal particles are bonded (sintered) in a solid state to form island-like crystals 3. Further, by performing the heat treatment step S3, a diffusion layer 5 in which a noble metal element and Ti of the substrate 2 are mutually diffused can be provided between the island-like crystal 3 and the substrate 2.

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 this crystallization, the passive film immediately below the island-like crystal 3 containing the noble metal is thinned by diffusion of oxygen into the Ti base material because the supply of oxygen is blocked by the island-like crystal 3. And changes to titanium oxide deficient in oxygen (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 directly under the island-like crystal 3 can be improved by heat treatment. 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 is heat-treated, and is covered with the noble metal island-like crystal 3. It is easier to obtain heat treatment if the heat treatment is performed under a condition with less oxygen, such as a spot.
Further, by continuing the heat treatment or increasing the heat treatment temperature, the passive film before the heat treatment and the layer of titanium oxide having high conductivity formed as described above disappear, and the island-like crystals A diffusion layer 5 in which a noble metal element and Ti are mutually diffused is formed between 3 and the substrate 2.

The temperature of the heat treatment in the heat treatment step S3 is preferably 300 to 800 ° C.
When the temperature of the heat treatment is less than 300 ° C., the noble metal particles attached to the surface of the substrate 2 are difficult to fuse with each other, so that it is difficult to form the island-like crystal 3 containing the noble metal. It becomes difficult to make the crystal 3 a desired size. Therefore, there is a possibility that good corrosion resistance and conductivity cannot be obtained. In addition, the diffusion rate of oxygen into the substrate 2 is slow, and it takes time to eliminate the passive film, which is not preferable.

On the other hand, when the temperature of the heat treatment exceeds 800 ° C., the noble metal and Ti diffuse too much to each other, so almost all the elements of the noble metal diffuse into the Ti of the substrate 2 and the surface of the island-like crystal 3 Will not remain. Moreover, if it takes out from a heat processing furnace in this state, there exists a possibility that the Ti oxide film 4 may be formed in the surface of the board | substrate 2 too thickly, contact resistance cannot be reduced, and favorable electroconductivity can be obtained. There are cases where it is not possible. Further, even in the case where the oxidation of Ti is promoted by oxygen in the furnace atmosphere and the diffusion layer 5 made of the noble metal element and Ti of the substrate 2 is formed, the lower side (for example, the diffusion layer 5 and the like) The oxide film 4 is formed between the substrate 2 and the conductivity may be lowered.
In addition, it is more preferable that the temperature of heat processing shall be 350-750 degreeC.

The heat treatment time in the heat treatment step S3 is preferably 1 to 60 minutes although it depends on the temperature of the heat treatment.
If the heat treatment time is less than 1 minute, the noble metal particles adhered to the surface of the substrate 2 cannot be sufficiently aggregated, so that it is difficult to form the desired island-like crystals 3, It becomes difficult to make the crystal 3 a desired size. Further, in the lower part of the island-shaped crystal 3, the diffusion of the noble metal element and Ti of the substrate 2 is insufficient, and there is a possibility that the bonding force for bonding the island-shaped crystal 3 and the substrate 2 cannot be obtained sufficiently. is there. Therefore, there is a possibility that good corrosion resistance and conductivity cannot be obtained.
On the other hand, when the heat treatment time exceeds 60 minutes, the desired island-like crystal 3 is no longer formed, and thus no further effect can be expected, which is not preferable from an economical viewpoint, and also depends on the temperature of the heat treatment. However, it is not preferable because noble metal and Ti 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). ).

Specifically, when the noble metal is at least one selected from Ru, Rh, Pd, Os, and Ir, the oxygen partial pressure should be 0.133 Pa (1 × 10 ⁻³ Torr) or less. preferable.
When the oxygen partial pressure in the heat treatment step S3 exceeds 0.133 Pa (1 × 10 ⁻³ Torr), there is too much oxygen in the atmosphere in which the heat treatment is performed, so that the island-like crystals 3 containing the noble metal are aggregated However, during the heat treatment, Ti on the surface of the substrate 2 may be oxidized and the oxide film 4 may be formed too thick, or the oxide film 4 may be formed between the diffusion layer 5 and the substrate 2. There is a possibility that the contact resistance cannot be reduced and good conductivity cannot be obtained. The oxygen partial pressure is preferably as low as possible, more preferably 0.0133 Pa (1 × 10 ⁻⁴ Torr) or less, and still more preferably 0.00133 Pa (1 × 10 ⁻⁵ Torr) or less.

Even under low oxygen partial pressure conditions, Ti is oxidized as long as oxygen is present in the atmosphere. However, since the oxidation of Ti does not proceed excessively under the low oxygen partial pressure conditions as described above, even if there is a place where the island-like crystal 3 is not formed on the substrate 2, An appropriate oxide film 4 is formed.
That is, even when used in an acidic atmosphere, the portion where the island-like crystal 3 is formed has good conductivity while the island-like crystal 3 has good corrosion resistance. Since the oxide film 4 is formed at the places where the island-like crystals 3 are not formed, the corrosion resistance is not deteriorated.

On the other hand, since Au and Pt are not oxidized, heat treatment can be performed at a pressure near atmospheric pressure. 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.
It is known that the corrosion resistance of the titanium oxide layer oxidized at a high temperature is superior to that of the passive film.
Therefore, even when the fuel cell separator 1 having the island-like crystals 3 and the oxide film 4 is used in an acidic atmosphere, the island-like crystals 3 containing the noble metal are formed. The portion can have good corrosion resistance by the island-shaped crystal 3 while having good conductivity, and the oxide film 4 is formed at the portion where the island-shaped crystal 3 is not formed. Therefore, the corrosion resistance does not deteriorate.

Note that the heat treatment conditions such as the heat treatment temperature, the heat treatment time, and the oxygen partial pressure are suitably set according to the type of the noble metal used.
Further, the heat treatment of the Ti or Ti alloy substrate 2 to which the noble metal particles are adhered can be performed by using a conventionally known heat treatment furnace such as an electric furnace or a gas furnace capable of reducing the pressure in the furnace.

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.

On the other hand, the oxide film 4 formed by heat treatment at 300 to 800 ° C. as in the present invention contains at least one of a rutile type crystal and a brookite type crystal, and therefore has an effect of preventing hydrogen absorption (simply "Hydrogen absorption prevention effect") is higher than amorphous passive film. Therefore, even when exposed to hydrogen under high temperature and high pressure as described above, Ti in the base material of the substrate 2 does not bond with hydrogen, and the base material is not easily embrittled. The above-described hydrogen absorption inhibiting effect can also be obtained by heat treatment under a high oxygen partial pressure such as atmospheric pressure conditions. In order to combine the hydrogen absorption inhibiting effect and conductivity, the heat treatment step of the present invention. The oxygen partial pressure of S3 is preferably 0.133 Pa (1 × 10 ⁻³ Torr) or less.

  Here, depending on the type of noble metal used, there is an element that absorbs hydrogen, so that the oxide film 4 formed during the heat treatment is not completely lost at the portion where the noble metal island-like crystal 3 and the substrate 2 are in contact with each other. Thus, by adjusting the heat treatment temperature and the heat treatment time, the diffusion layer 5 is formed between the island-like crystal 3 and the substrate 2 (base material), that is, directly below the island-like crystal 3 (under the island-like crystal 3). If formed, a thin oxide film 4 having a thickness of about 0.5 to 10 nm (hereinafter referred to as “titanium oxide layer 41”) is formed immediately below the diffusion layer 5 (that is, at the interface). ) Is allowed to remain, the thin oxide film 4 (titanium oxide layer 41) can have both a hydrogen absorption preventing effect and conductivity. Since the titanium oxide layer 41 is covered with the island-like crystal 3 and is formed under a condition with less oxygen, as described above, at least the rutile type crystal and the brookite type crystal than the oxide film 4 are used. One can be contained in a large amount.

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, the substrate 2 made of Ti or Ti alloy is immersed in an acid solution containing ions of at least one kind of noble metal selected from Ru, Rh, Pd, Os, Ir, Pt and Au. An adhesion step for depositing and adhering noble metal particles on the surface of the substrate, and a gas flow path for distributing gas to at least a part of the surface of the substrate 2 on which noble metal particles are deposited and adhered by, for example, pressing Forming a recess for forming the substrate, and a heat treatment process for forming an island-like crystal 3 including a noble metal on the surface of the substrate 2 by heat-treating the substrate 2 on which the recess is formed. It can be set as the manufacturing method of the separator for fuel cells.

  Further, for example, the substrate 2 made of Ti or Ti alloy is immersed in an acid solution containing ions of at least one kind of noble metal selected from Ru, Rh, Pd, Os, Ir, Pt and Au. An adhesion step of depositing and adhering noble metal particles on the surface of the substrate 2 and heat-treating the substrate 2 on which noble metal particles have been deposited and adhering, thereby forming an island-like structure containing noble metal on the surface of the substrate 2 A heat treatment step for forming the crystal 3 and a recess for forming a gas flow path through which the gas is circulated are formed on at least a part of the surface of the substrate 2 on which the island-shaped crystal 3 is formed by, for example, pressing. A method for producing a fuel cell separator including the forming step.

Next, the fuel cell separator 1 according to the present invention manufactured by the method for manufacturing the fuel cell separator of the present invention will be described in detail.
As shown in FIG. 2 (a), the fuel cell separator 1 according to the present invention is provided 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. An island-like crystal 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 substrate 2 made of Ti or Ti alloy. ing.
As described above, the island-shaped crystal 3 is a substrate in which a recess is formed in an acid solution containing ions of at least one kind of noble metal selected from Ru, Rh, Pd, Os, Ir, Pt and Au. 2 is obtained by precipitating and adhering noble metal particles to the surface of the substrate 2 and heat-treating them, and the details thereof are as described above, and the description thereof is omitted.

The island-shaped crystal 3 preferably has a size of 100 nm or more and 10 μm or less.
If the size of the island-shaped crystal 3 containing the noble metal is less than 100 nm, there is a possibility that good conductivity cannot be obtained because the diameter is small. On the other hand, when the size of the island-like crystal 3 containing the noble metal exceeds 10 μm, the adhesion with the Ti of the substrate 2 is deteriorated and may fall off.
The height (thickness) of the island-like crystals 3 is preferably 50 to 1000 nm.

  Moreover, it is preferable to have a diffusion layer 5 in which a noble metal element and Ti of the substrate 2 are diffused between the island-like crystal 3 and the substrate 2. As described above, good conductivity and corrosion resistance are obtained by the island-shaped crystal 3 including the noble metal, while the electric resistance (contact resistance) between the island-shaped crystal 3 and the substrate 2 is obtained by the diffusion layer 5. I try not to be high. In addition, by having such a diffusion layer 5, the bonding force for bonding the island-shaped crystal 3 and the substrate 2 can be increased, so that the adhesion between the island-shaped crystal 3 and the substrate 2 is improved. Can do.

The preferred thickness of the diffusion layer 5 is 2 to 10 nm. If the thickness of the diffusion layer 5 is within these ranges, the above-described effects can be suitably achieved.
The thickness of the diffusion layer 5 can be realized by performing a heat treatment under appropriate conditions. It is preferable that the heat treatment under appropriate conditions is determined by an appropriate experiment or the like in accordance with the type of the noble metal used within the range of the heat treatment temperature and the heat treatment time.

Further, in the fuel cell separator 1 according to the present invention, as shown in FIG. 2A, Ti on the surface of the substrate 2 is oxidized in the portion where the island-like crystals 3 are not formed on the surface of the substrate 2. It is preferable that the oxide film 4 is formed. This is because the oxide film 4 can provide good corrosion resistance.
The thickness of the oxide film 4 is preferably 1 to 50 nm.
When the thickness of the oxide film 4 is less than 1 nm, the thickness of the oxide film 4 is not sufficient, so that pinholes are formed by use in an acidic atmosphere, and Ti of the substrate 2 is eluted, which is used for a fuel cell. In addition, power generation characteristics may deteriorate.
On the other hand, the fact that the thickness of the oxide film 4 exceeds 50 nm means that the oxidation of Ti has progressed too much. For example, the oxide film 4 is formed between the diffusion layer 5 and the substrate 2. Therefore, there is a possibility that the conductivity is lowered.
The thickness of the oxide film 4 can be measured by using, for example, SEM / EDX (scanning electron microscope with energy dispersive X-ray diffraction analyzer).

In addition, the formation amount of the island-like crystal 3 including the noble metal formed on the surface of the fuel cell separator 1 can be measured by performing SEM / EDX analysis.
The separator 1 for a fuel cell according to the present invention is a SEM on the surface of the substrate 1 on which the island-like crystals 3 are formed under the conditions of, for example, acceleration voltage: 20 kV, magnification: 5000 times (field of view: approximately 9 × 11 μm). It is preferable that the amount of the noble metal forming the island-like crystal 3 when analyzed by / EDX is 0.1 at% (atomic percent) or more.
When the amount of the noble metal that forms the island-shaped crystal 3 in the SEM / EDX analysis is less than 0.1 at%, the amount of the island-shaped crystal 3 formed in the fuel cell separator 1 is reduced. Sexuality gets worse.
On the other hand, although there is no upper limit on the amount of the noble metal that forms the island-like crystal 3 when SEM / EDX analysis is performed, it is preferably 10 at% or less from the viewpoint of production cost.

  Further, when the fuel cell separator 1 according to the present invention includes the titanium oxide layer 41 described above, for example, as shown in FIG. 2B, selected from Ru, Rh, Pd, Os, Ir, Pt and Au. The island-shaped crystal 3 containing at least one kind of noble metal is formed, and more specifically, the island-shaped crystal between the island-shaped crystal 3 and the substrate 2 (that is, the base material). In the case where the diffusion layer 5 is formed immediately below 3, the above-described titanium oxide layer 41 is formed between the diffusion layer 5 and the substrate 2.

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. A predetermined number of fuel cell separators 1 are manufactured by performing the above-described adhesion step S2 and heat treatment step S3 on the substrate 2 on which the recesses are formed.

  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 produced 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 power generation performance and durability. A fuel cell (solid polymer fuel cell) 20 according to the present invention having the above can be produced.

  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, the fuel cell 20 according to the present invention uses the fuel cell separator 1 according to the present invention in which the island-like crystal 3 including at least a noble metal is formed. Compared to a fuel cell using a separator made of metal, good corrosion resistance and conductivity can be provided.

Next, the fuel cell separator manufacturing method, the fuel cell separator, and the fuel cell according to the present invention are specifically described 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. explain.
<Example A>
Nine Ti substrates (width 20 mm × 20 mm, thickness 1 mm) made of one kind of pure Ti specified in JIS H 4600 are prepared, and after ultrasonic cleaning in acetone, Au, Pt, Pd are each 1, It is immersed in an acid solution (0.02% hydrofluoric acid, 0.2% nitric acid) adjusted to contain 10 and 50 ppm for 20 minutes, and contains Au, Pt, and Pd on each Ti substrate by displacement plating. The particles were deposited in the form of islands (hereinafter referred to as test plates 1 to 9 for each noble metal species and concentration as shown in Table 1).

Thereafter, the test plates 1 to 9 on which the precious metal particles were deposited were heat-treated under the following heat treatment conditions using a heat treatment furnace. Test plates 1 to 6 using Au and Pt were heat-treated at 500 ° C. for 5 minutes in an air atmosphere. The test plates 7 to 9 using Pd were heat-treated at 0.665 Pa (5 × 10 ⁻³ Torr) at 500 ° C. for 30 minutes.

And the test plates 1-9 which performed the above-mentioned process using the contact resistance measuring apparatus 30 shown in FIG. 3 (In addition, in FIG. 3, the test plate 1 to the location represented as the separator 1 for fuel cells is shown. 9) is sandwiched between carbon cloths C and C, and the outside is pressurized with a load 98N (10 kgf) using copper electrodes 31 and 31 having a contact area of 1 cm ² , and a direct current power source 32 is used. The contact resistance was calculated by applying 1A electricity and measuring the voltage applied between the carbon cloths C and C with the voltmeter 33. The contact resistance was 15 mΩ · cm ² or less.

  Furthermore, after the test plates 1 to 9 were immersed in an aqueous sulfuric acid solution (pH 2) at 80 ° C. for 1000 hours, the contact resistance was measured again using the contact resistance measuring device 30 under the above conditions.

  Moreover, it formed in each surface of the test plates 1-9 by performing SEM / EDX (scanning electron microscope with an energy dispersive X-ray diffraction analyzer) with respect to the heat-treated test plates 1-9. The amount of noble metal in the island-like crystals comprising the noble metal was analyzed. The analysis conditions were an acceleration voltage of 20 kV and a magnification of 5000 times (field of view: 9 × 11 μm). In this analysis, five points were measured for each of the test plates 1 to 9, and the average value was obtained as the amount of noble metal [at%].

Precious metal species used, concentration of precious metal contained in acid solution [ppm], immersion time [minute], contact resistance before sulfuric acid immersion [mΩ · cm ² ], contact resistance after 1000 hours of sulfuric acid immersion [mΩ · cm ² ] and the amount of noble metal [at%] are shown in Table 1.
Further, in order to examine the interface structure between the island-like crystal containing the noble metal and the Ti substrate, the cross section of the test plate 9 was observed with a transmission electron microscope (TEM). The observation conditions were a sample thickness of about 100 nm, an acceleration voltage of 200 kV, and a magnification of 1.5 million times.

As shown in Table 1, the test plates 2, 3, 5, 6, 8, and 9 satisfy the requirements of the present invention in terms of the concentration of the noble metal contained in the acid solution, the time of immersion in the acid solution, and the heat treatment conditions. Therefore, it was found that the amount of island-like crystals (noble metal amount) containing noble metal formed on the Ti substrate was 0.40 at% or more.
Moreover, it was found that the contact resistance before dipping in the sulfuric acid aqueous solution is 4.5 mΩ · cm ² or less, and the contact resistance is low.
Furthermore, the contact resistance after being immersed in an aqueous sulfuric acid solution for 1000 hours was 6.5 mΩ · cm ² or less, and the contact resistance was low, so that it was found that the contact resistance could be stably maintained for a long time.
Moreover, from the result of observation by TEM, it was confirmed that there was a titanium oxide layer having a thickness of about 3 to 5 nm between the island-like crystal containing Pd 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 crystal and brookite crystal were included.

On the other hand, the test plates 1, 4, and 7 had a noble metal concentration in the acid solution that did not satisfy the requirements of the present invention, and therefore the amount of island-like crystals containing the noble metal formed on the Ti substrate (noble metal) ) Was as low as 0.08 at% or less. For this reason, it was found that the contact resistance before immersion in an aqueous sulfuric acid solution was 30.5 mΩ · cm ² or more, and the contact resistance after 1000 hours of immersion in an aqueous sulfuric acid solution was as high as 156.2 mΩ · cm ² or more.

In addition, a test plate is prepared in which no precious metal particles adhere to a Ti substrate (width 20 mm × 20 mm, thickness 1 mm) made of one kind of pure Ti specified in JIS H 4600, and no heat treatment is performed. Similarly to 1-9, the contact resistance before and after being immersed in an 80 ° C. sulfuric acid aqueous solution (pH 2) for 1000 hours was measured using the contact resistance measuring device 30 in the same manner as described above.
As a result, the contact resistance before immersing in an 80 ° C. sulfuric acid aqueous solution (pH 2) for 1000 hours was 49.5 mΩ · cm ² , and the contact resistance after immersing in an 80 ° C. sulfuric acid aqueous solution (pH 2) for 1000 hours was 1572. It was 5 mΩ · cm ² .

<Example B>
Prepare 11 Ti substrates (width 20mm x 20mm, thickness 1mm) made of one kind of pure Ti as defined in JIS H 4600, ultrasonically wash in acetone, and contain 20 ppm each of Au and Pd. Were immersed in an acid solution (0.02% hydrofluoric acid, 0.2% nitric acid) for 20 minutes, and particles containing Au and Pd were deposited in an island shape on each Ti substrate by displacement plating. . Then, each Ti substrate was subjected to heat treatment under the heat treatment conditions (pressure conditions, heat treatment temperature and heat treatment time) shown in Table 2 below. As shown in Table 2, the Ti substrate on which Au was deposited was heat-treated at 250 ° C., 300 ° C., 500 ° C., 700 ° C., and 850 ° C. for 5 minutes in the air atmosphere. On the other hand, on the Ti substrate on which Pd was deposited, heat treatment was performed at 0.665 Pa (5 × 10 ⁻³ Torr) at 250 ° C., 300 ° C., 500 ° C., 700 ° C., and 850 ° C. for 30 minutes (hereinafter referred to as these). As test plates 10 to 20 for each noble metal species and heat treatment conditions as shown in Table 2).

After heat-treating the test plates 10 to 20 on which Au or Pd is deposited, both surfaces of the test plates 10 to 20 subjected to the above-described treatment are made of carbon cloth C and C using the contact resistance measuring device 30 shown in FIG. Further, the outside is pressurized with a load 98 N (10 kgf) using copper electrodes 31, 31 with a contact area of 1 cm ² , 1 A electricity is applied using a DC current power supply 32, and the carbon cloth C is connected between the carbon cloths C, C. The applied voltage was measured with a voltmeter 33 to calculate the contact resistance.

  Furthermore, after the test plates 10 to 20 were immersed in an aqueous sulfuric acid solution (pH 2) at 80 ° C. for 1000 hours, the contact resistance was measured again using the contact resistance measuring device 30 under the above conditions.

  Moreover, it formed in each surface of the test plates 10-20 by performing SEM / EDX (scanning electron microscope with an energy dispersion type | mold X-ray diffraction analyzer) with respect to the test plates 10-20 which heat-processed. The amount of noble metal in the island-like crystals comprising the noble metal was analyzed. The analysis conditions were an acceleration voltage of 20 kV and a magnification of 5000 times (field of view: 9 × 11 μm). In this analysis, five points were measured for each of the test plates 10 to 20, and the average value was obtained as the amount of noble metal [at%].

Precious metal species used, pressure conditions, heat treatment temperature [° C.], heat treatment time [minutes], contact resistance before sulfuric acid immersion [mΩ · cm ² ], contact resistance after sulfuric acid 1000 hour immersion [mΩ · cm ² ] and precious metal The amount [at%] is shown in Table 2.

As shown in Table 2, since the test plates 11 to 13 and 17 to 19 satisfied the requirements of the present invention for the pressure conditions, the heat treatment temperature, and the heat treatment time, the islands containing the noble metal formed on the Ti substrate were used. It was found that the amount of shaped crystals (the amount of noble metal) was 0.88 at% or more.
Further, it was found that the contact resistance before dipping in the sulfuric acid aqueous solution was 12 mΩ · cm ² or less, and the contact resistance was low.
Furthermore, since the contact resistance after being immersed in sulfuric acid aqueous solution was 14.5 mΩ · cm ² or less and had low contact resistance, it was found that low contact resistance can be stably maintained for a long time.

On the other hand, since any of the pressure conditions, the heat treatment temperature, and the heat treatment time did not satisfy the requirements of the present invention for the test plates 10, 14 to 16, 20, the passive film on the Ti substrate could not be removed, or noble metal It was found that the contact resistance was increased due to the formation of a noble metal that formed an island-shaped crystal containing or an oxide film formed under the island-shaped crystal (under the diffusion layer). It was. Specifically, it was found that the contact resistance before being immersed in the sulfuric acid aqueous solution was 13.5 mΩ · cm ² or more and the contact resistance after being immersed in the sulfuric acid aqueous solution was 25.3 mΩ · cm ² or more.

<Example C>
Eight Ti substrates (width 2 cm x 5 cm, thickness 0.2 mm) made of one kind of pure Ti specified in JIS H 4600 are prepared, and after ultrasonic cleaning in acetone, each contains 20 ppm of Au or Pt. Soaked in an acid solution (0.02% hydrofluoric acid, 0.2% nitric acid) for 20 minutes and deposited particles of Au or Pt on the surface of each Ti substrate in an island shape by displacement plating (Attached) (test plates 21 to 28).
Of these, as shown in Table 3 below, the test plates 22 and 26 were subjected to heat treatment under atmospheric pressure conditions (oxygen partial pressure 2.13 × 10 ⁴ Pa), a heat treatment temperature of 500 ° C., and a heat treatment time of 1 minute. went.
Moreover, after putting the test plates 23, 24, 27, and 28 into a vacuum heat treatment furnace and evacuating them to 0.00133 Pa (1 × 10 ⁻⁵ Torr), they are heated to 500 ° C., and dry air is introduced into the furnace. As shown in Table 3 below, the oxygen partial pressure is adjusted to be either 0.133 Pa (1 × 10 ⁻³ Torr) or 0.00133 Pa (1 × 10 ⁻⁵ Torr). Heat treatment was performed at a heat treatment temperature of 30 ° C. for 30 minutes.
For comparison, the test plates 21 and 25 were not subjected to heat treatment under the heat treatment conditions shown in Table 3 below.

The contact resistances (mΩ · cm ² ) of the test plates 21 to 28 thus treated were measured and calculated under the same conditions as those described in <Example A> and <Example B>.
Further, the test plates 21 to 28 are put in a gas phase part of a sealed container containing water and 0.3 MPa (3 atm) of hydrogen, and heated at 120 ° C. to humidify to about 100% humidity. After being exposed for 500 hours in a pure hydrogen (purity 99.99%) atmosphere (hereinafter, simply referred to as “humidified pure hydrogen atmosphere”), and then 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 to extract hydrogen 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 as a thermal conductivity detector. The hydrogen concentration (ppm) in the test plates 21 to 28 was measured by measuring the change in thermal conductivity caused by hydrogen (inert gas melting-gas chromatograph method).
The contact resistance and the hydrogen concentration in the test plates 21 to 28 (shown as “hydrogen concentration in the test plate” in Table 3) are shown in Table 3 below together with the heat treatment conditions described above. Note that the contact resistance was 12 mΩ · cm ² or less, and the hydrogen concentration in the Ti substrate was 70 ppm or less.

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 21 and 25 that were not heat-treated under the heat treatment conditions shown in Table 3 have high values of contact resistance and hydrogen concentration in the Ti substrate, and good results can be obtained. There wasn't.
On the other hand, as shown in Table 3, the test plates 22 to 24 and 26 to 28 subjected to heat treatment at an oxygen partial pressure of 2.13 × 10 ⁴ Pa, 0.133 Pa, or 0.00133 Pa are all in contact. The resistance and the hydrogen concentration in the Ti substrate were low, and good results could be obtained.

  From the results of <Example C>, the test plates 22 to 24 and 26 to 28 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>
Next, in <Example D>, a power generation test was performed in the case of using a separator manufactured using the Ti substrate of the test plate 9 described above.
First, two Ti substrates each having a length of 95.2 mm × width of 95.2 mm × thickness of 19 mm are prepared, and a gas having a groove width of 0.6 mm and a groove depth of 0.5 mm is machined at the center of the surface. The flow path was produced in the shape shown in FIG. Then, on the surface of the Ti substrate on which the gas flow path was formed, palladium chloride was applied and heat-treated under the same method and conditions as in <Example A> to produce a separator.

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 entire fuel cell was heated and maintained at 80 ° C., and hydrogen gas and air were passed through heated water to adjust the dew point temperature to 80 ° C. and introduced into the fuel cell at a pressure of 2 atm. .

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 9 and the voltage after 100 hours of power generation were both 0.61 V, and no voltage change was observed.

In addition, as a comparison object, instead of the Ti substrate separator of the test plate 9, a conventionally used graphite separator (manufactured by Electrochem, FC-05-MP) is arranged to produce a fuel cell, which is the same as described above. A power generation test was conducted under the conditions.
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 Ti substrate separator of the test plate 9.

  From the above results, it was found that the substrate made of Ti or Ti alloy produced by the method for producing a fuel cell separator of the present invention exhibits the same performance as a graphite separator even if 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.

It is a flowchart explaining the process of the manufacturing method of the separator for fuel cells which concerns on this invention. (A) And (b) 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.

Explanation of symbols

S1 formation process S2 adhesion process S3 heat treatment process 1 fuel cell separator 2 substrate 3 island-like crystal 4 oxide film 5 diffusion layer 10 single cell 11 gas flow path 12 gas diffusion layer 13 solid polymer film 20 fuel cell

Claims (11)

Forming step for forming a recess for forming a gas flow path through which gas flows in at least part of the surface of the substrate as a fuel cell separator made of Ti or Ti alloy;
The substrate having the recesses is dipped in an acid solution containing ions of at least one or more kinds of noble metals selected from Ru, Rh, Pd, Os, Ir, Pt, and Au, and the noble metal is immersed on the surface of the substrate. An adhesion step of depositing and adhering particles of
A heat treatment step of forming an island-like crystal containing the noble metal on the surface of the substrate by heat-treating the substrate to which the particles are attached;
The manufacturing method of the separator for fuel cells characterized by including these.   The method for producing a fuel cell separator according to claim 1, wherein the temperature of the heat treatment in the heat treatment step is 300 to 800 ° C.   The method for producing a fuel cell separator according to claim 1 or 2, wherein an oxygen partial pressure in the heat treatment step is 0.133 Pa or less.   A substrate as a separator for a fuel cell made of Ti or Ti alloy having a recess for forming a gas flow path through which gas flows on at least a part of the surface is made of Ru, Rh, Pd, Os, Ir, Pt and A fuel cell separator obtained by immersing in an acid solution containing ions of at least one kind of noble metal selected from Au, and heat-treating the substrate immersed in the acid solution.   The fuel cell separator according to claim 4, wherein the temperature of the heat treatment is 300 to 800 ° C.   6. The fuel cell separator according to claim 4, wherein an oxygen partial pressure in the heat treatment is 0.133 Pa or less. 7. Ru, Rh, Pd, Os, Ir, on the surface of a substrate as a separator for a fuel cell made of Ti or Ti alloy in which a recess for forming a gas flow path for allowing gas to flow through at least a part of the surface is formed. Having an island-shaped crystal containing at least one or more kinds of noble metals selected from Pt and Au, and
A fuel cell separator comprising a diffusion layer in which the element of the noble metal and Ti of the substrate are diffused between the island-shaped crystals and the substrate.   The portion of the surface of the substrate where the island-like crystals are not formed forms an oxide film in which Ti on the surface of the substrate is oxidized during a heat treatment step. Fuel cell separator.   The amount of the noble metal forming the island-shaped crystal when the surface of the substrate on which the island-shaped crystal is formed is measured by SEM / EDX analysis is 0.1 at% or more. Or the separator for fuel cells of Claim 8.   The surface of the substrate made of Ti or Ti alloy in which a recess for forming a gas flow path for flowing gas is formed on at least a part of the surface is selected from Ru, Rh, Pd, Os, Ir, Pt and Au. An island-shaped crystal containing at least one kind of noble metal is formed, and a titanium oxide layer containing at least one of a rutile crystal and a brookite crystal is formed between the island-shaped crystal and the substrate. A fuel cell separator characterized by the above.   A fuel cell comprising the fuel cell separator according to any one of claims 4 to 10.

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