JP5391855B2 - Conductive member, method for producing the same, fuel cell separator using the same, and polymer electrolyte fuel cell - Google Patents

Description

  The present invention relates to a conductive member, a method for producing the same, and a fuel cell separator and a polymer electrolyte fuel cell using the same. In particular, the present invention relates to a method for producing a conductive member that can enhance the anticorrosion effect of a metal substrate and can be applied as a substrate of a separator even in the case of a metal that is easily corroded such as aluminum.

  A polymer electrolyte fuel cell (PEFC) has a structure in which a plurality of single cells that exhibit a power generation function are stacked. Each of the single cells is also referred to as (1) a polymer electrolyte membrane (for example, a Nafion (registered trademark) membrane) and (2) a pair of (anode, cathode) catalyst layers (an “electrode catalyst layer”) sandwiching the membrane. ), And (3) a membrane electrode assembly (MEA) including a pair of (anode, cathode) gas diffusion layers (GDL) for dispersing the supply gas sandwiching them. And MEA which each single cell has is electrically connected with MEA of an adjacent single cell through a separator. In this way, a single cell is stacked and connected to form a fuel cell stack. The fuel cell stack can function as power generation means that can be used for various applications. In such a fuel cell stack, the separator exhibits a function of electrically connecting adjacent single cells as described above. In addition to this, a gas flow path is usually provided on the surface of the separator facing the MEA. The gas flow path functions as gas supply means for supplying fuel gas and oxidant gas to the anode and the cathode, respectively.

  Briefly explaining the power generation mechanism of the PEFC, during operation of the PEFC, a fuel gas (for example, hydrogen gas) is supplied to the anode side of the single cell, and an oxidant gas (for example, air or oxygen) is supplied to the cathode side. As a result, in each of the anode and the cathode, an electrochemical reaction represented by the following reaction formula proceeds to generate electricity.

  Conventionally, metals, carbon, or conductive resins are known as constituent materials for fuel cell separators that require electrical conductivity. Among these, in the carbon separator and the conductive resin separator, it is necessary to set the thickness relatively large in order to secure the strength after forming the gas flow path to some extent. As a result, the overall thickness of the fuel cell stack using these separators also increases. Such an increase in the size of the stack is not preferable particularly in an in-vehicle PEFC that requires a reduction in size.

  On the other hand, since the metal separator has a relatively high strength, the thickness can be made relatively small. Moreover, since it is excellent also in electroconductivity, when a metal separator is used, there also exists an advantage that contact resistance with MEA can be reduced. On the other hand, in metal materials, there may be a problem that the conductivity is lowered due to corrosion (for example, due to generated water or a potential difference generated during operation), and the output of the stack is lowered accordingly. Therefore, the metal separator is required to improve the corrosion resistance while ensuring its excellent conductivity.

  Here, a metal layer such as Ti or a carbide layer thereof is formed on one surface of the metal substrate of the metal separator, and a carbon layer (conductive carbon) made of graphitized carbon on the metal layer or the carbide layer. A technique for forming a film) has been proposed (see, for example, Patent Document 1). In this document, while applying a negative high voltage to a separator substrate in an inert gas atmosphere, a metal layer or a carbide layer thereof, and further a carbon layer using a metal material or a carbon-based material by a dry film formation method on the substrate surface. Forming a layer. Thereby, since the carbon layer is formed while the positive ions of the inert gas collide with the separator substrate, the inside of the carbon layer can be reliably graphitized. In addition, the adhesion between the separator substrate and the carbon layer can be improved by forming a metal layer or its carbide layer as an intermediate layer. As a result, a fuel cell separator having excellent corrosion resistance and conductivity can be provided.

JP 2006-286457 A

  When a conductive carbon film is formed on a substrate of a metal separator provided by the technique described in the conventional patent document 1, an intermediate layer such as a metal layer or its carbide layer is provided to ensure adhesion. However, the crystal structure of the intermediate layer is not controlled. For this reason, there are many gaps in the intermediate layer and the film is not dense. Therefore, there arises a problem that the anticorrosion function of the substrate is not sufficient and the denseness of the conductive carbon film laminated on the intermediate layer cannot be improved.

  Therefore, the present invention provides a means (manufacturing method) for suppressing an increase in contact resistance while sufficiently securing the excellent conductivity in a conductive member having a dense intermediate layer between a metal substrate and a conductive carbon layer. ).

  The present inventors have found that the above problem can be solved by controlling the crystal structure of the intermediate layer, and have completed the present invention.

  Such a method for producing a conductive member of the present invention includes a step of forming an intermediate layer on a metal substrate and a step of forming a conductive carbon layer on the intermediate layer in a dry film formation method, The negative bias voltage at the time of forming the intermediate layer is changed from at least a low value to a high value.

  According to the present invention, when the bias voltage in the dry film forming method is a low value, the column diameter of the columnar crystal is small, and when the bias voltage is high, the column diameter is large. In the initial stage of intermediate layer deposition in the dry deposition method, deposition is started at a low bias voltage so as not to deteriorate the roughness of the interface with the substrate, and then the bias voltage is shifted to a high value to form columnar crystals. Grow thick. The conductive carbon film grows with the column diameter of the columnar crystals in the intermediate layer. By increasing the column diameter of the columnar crystals in the intermediate layer, the gaps in the intermediate layer and the defects in the conductive carbon film present on the intermediate layer are reduced, and the oxidation at each interface is suppressed by preventing water from entering. , Suppress the increase of contact resistance. Moreover, as a manufacturing method, it is a simple method which only changes the set value of the apparatus.

It is a section schematic diagram showing the basic composition of the cell unit of the polymer electrolyte fuel cell (PEFC) which uses the separator to which the conductive member concerning the present invention is applied. It is a cross-sectional schematic diagram which shows typically the structure of the metal base material of the separator used for the fuel cell unit of FIG. 1, and the process layer formed on this base material. FIG. 2 is a cross-sectional view showing another embodiment of the schematic configuration of the separator portion in FIG. 1, which has columnar crystal structures on both surfaces of the metal substrate of the separator used in the fuel cell unit of FIG. 1. 1 is a schematic cross-sectional view schematically showing a configuration in which an intermediate layer and a conductive carbon layer having protruding particles on the outermost surface are provided. It is the enlarged view which expanded a part of FIG. 3A, and clarified the structure of the electroconductive carbon layer in which the protruding layer particle exists in the intermediate | middle layer which has a thick columnar crystal structure, and outermost surface. In contrast with FIG. 3B, the metal substrate of the separator used in the fuel cell unit of the prior art, the intermediate layer having a thin needle crystal structure, and the conductive carbon layer having no protruding particles on the outermost surface. It is the enlarged view which clarified the structure more. In FIG. 3B, H ₁ , H ₂ , H ₃ ,... Indicate the height of the protruding particles on the outermost surface of the conductive carbon layer 33 (projection height), and W ₁ , W ₂ , W ₃ ,. The thickness (column diameter, width) of the columnar crystal structure in the intermediate layer 32 is indicated. Reference numeral 33 a in FIG. 3B indicates the protruding particles on the outermost surface of the conductive carbon layer 33. It is the photograph (magnification: 400,000 times) which observed the section of the conductive member (conductive member A) which has the conductive carbon layer of R = 1.0-1.2 with the transmission electron microscope (TEM). It is the photograph (magnification: 400,000 times) which observed the section of the conductive member (conductive member B) which has the conductive carbon layer of R = 1.6 by TEM. It is a schematic diagram which shows the 3 times symmetrical pattern of an average peak in the rotational anisotropy measurement of a Raman scattering spectroscopy analysis. It is a schematic diagram which shows the 2 times symmetrical pattern of an average peak in the rotational anisotropy measurement of a Raman scattering spectroscopy analysis. It is a schematic diagram which shows the pattern which does not show the symmetry of an average peak in the rotational anisotropy measurement of a Raman scattering spectroscopy analysis. It is a graph which shows the Raman spectrum when the electrically conductive member B is used as a measurement sample and the rotation angles of the sample are 0 °, 60 ° and 180 °, respectively. 5 is a graph showing an average peak of rotational anisotropy measurement for conductive member B. Values of the Vickers hardness of the conductive carbon layer and the sp3 ratio of the conductive carbon layer in several conductive members having different Vickers hardness of the conductive carbon layer by changing the bias voltage and the film formation method by sputtering. It is a figure which shows the relationship. It is a graph which shows the result of having measured contact resistance about several electrically-conductive members which have a conductive carbon layer from which content of hydrogen atoms differs although R value is 1.3 or more. It is a conceptual diagram of the vehicle carrying the fuel cell stack of one Embodiment of this invention. It is a schematic diagram which shows the outline | summary of the measuring apparatus used in measuring the contact resistance in an Example. It is a graph which shows the result of having measured the contact resistance before and after an immersion test about the electrically-conductive member produced in Example 1 and Comparative Example 1. FIG. It is a graph which shows the result of having measured the contact resistance before and after an immersion test about the electrically-conductive member produced in each reference example and a comparative example. It is the schematic which shows the fuel cell (stack) including the current collecting plate of the fuel cell of Embodiment 1 to which the conductive member of the present invention is applied. FIG. 12 is a perspective view of the fuel cell (stack) of FIG. 11. FIGS. 13a and 13b are SEM observation (surface) drawings (FIG. 13a) of Comparative Example 1 and SEM observation (surface) drawings (FIG. 13b) of Example 1. FIG. 14a and 14b are an enlarged view (FIG. 14a) of the SEM observation (surface) of Comparative Example 1 (FIG. 13a) and an enlarged view of the SEM observation (surface) drawing of Example 1 (FIG. 13b). (FIG. 14b). 15a and 15b are a TEM observation (cross-section) surface view (FIG. 15a) of Comparative Example 1 and a TEM observation (cross-section) drawing of Example 1 (FIG. 15b). 16a and 16b are a surface view (FIG. 16a) of SEM observation (cross section) of Comparative Example 1 and a drawing (FIG. 16b) of the SEM observation (cross section) of Example 1. FIG. FIG. 17 is also a drawing of SEM observation (surface) of Example 1. FIG. 18 is an enlarged view of FIG. FIG. 19 is also a drawing of SEM observation (surface) of Example 2. 20A to 20F are diagrams showing various patterns obtained by changing the negative bias voltage at the time of forming the intermediate layer in the dry film forming method from at least a low value to a high value. Among these, FIG. It is drawing which showed one example of the pattern which changes a bias voltage from a low value to a high value in one step. FIG. 20B is a diagram showing an example of a pattern obtained by continuously changing the negative bias voltage during the formation of the intermediate layer from a low value to a high value in the dry film forming method. FIG. 20C is a drawing showing an example of a pattern obtained by changing the negative bias voltage during the formation of the intermediate layer in a dry film formation method from a low value to a high value in multiple steps. FIG. 20D is a drawing showing an example of a pattern obtained by continuously changing the negative bias voltage during intermediate layer formation in a dry film formation method from a low value to a high value in multiple steps. FIG. 20E shows that after changing the negative bias voltage at the time of intermediate layer formation in the dry film formation method once from a low value to a high value (may or may not be held at a high position for a certain period of time). After that, it is a drawing showing an example of a pattern that is changed to return from a high value to a low value again. FIG. 20F shows that after changing the negative bias voltage at the time of forming the intermediate layer in the dry film formation method once from a low value to a high value (may or may not be held at a high position for a certain period of time). After that, it is a drawing showing an example of a pattern that is changed like a pulse wave. The conductive member of the present invention, in particular, at least one of each of the intermediate layer and the conductive carbon layer, preferably each of these layers is sequentially formed by sputtering (for example, unbalanced magnetron sputtering (UBMS)). FIG. 2 is a schematic plan view of a manufacturing apparatus for forming (however, an example in which an existing disk-shaped wafer is set in place of a flat plate-shaped metal separator before pressing of unevenness) is shown. Manufacturing apparatus for forming (forming) at least one of the conductive members of the present invention, particularly the intermediate layer and the conductive carbon layer, preferably using the arc ion plating (AIP) method in order. FIG. 2 is a schematic plan view of an example in which an existing disk-shaped wafer is set in place of a flat plate type metal separator before uneven pressing.

(Method for producing conductive member)
The method for producing a conductive member of the present invention includes a step of forming an intermediate layer on a metal substrate and a step of forming a conductive carbon layer on the intermediate layer in the dry film forming method. The negative bias voltage is changed from at least a low value to a high value (referred to as the first embodiment). The manufacturing method of the first embodiment is a simple method that only changes the set value of a dry film forming method (sputtering, etc.) used during film formation, while sufficiently ensuring its excellent electrical conductivity and contact resistance. It is possible to provide and realize a conductive member that can suppress an increase in the amount of the material.

(Manufacturing method of the first embodiment)
The present embodiment is characterized in that in the dry film forming method, the negative bias voltage at the time of forming the intermediate layer is changed from at least a low value to a high value.

  Here, changing the bias voltage in the dry film-forming method from at least a low value to a high value means changing the bias voltage from a low value to a high value in one step as shown in FIGS. 20A), may be continuously changed from a low value to a high value (FIG. 20B), or may be changed in multiple steps from a low value to a high value (FIG. 20C). Further, it may be continuously changed in multiple steps from a low value to a high value (FIG. 20D). Alternatively, after changing from a low value to a high value once (may be held at a high position for a certain period of time or not), thereafter, the value may be returned from a high value to a low value again (FIG. 20E). ). Excellent economy. Similarly, after changing once from a low value to a high value (which may or may not be held at a high position for a certain period of time), thereafter, it may be changed like a pulse wave (see FIG. 20F) and the like are not limited at all.

  This is because when the intermediate layer is first formed on the metal base layer, the energy applied to the surface becomes high in order to make the column thick from the beginning, which may cause poor adhesion. Therefore, it is preferable that the thickness of the column diameter on the metal substrate side of the intermediate layer thickness is thinner than that on the conductive carbon layer side. Therefore, it is necessary to set the bias voltage to at least a low value at least in a region corresponding to the initial stage of film formation of the intermediate layer. The magnitude (absolute value) of the negative bias voltage only needs to indicate a voltage exceeding 0 V, and the above characteristics can be effectively exhibited as long as it is generally in the range of 0 V to 50 V. .

  It is desirable that the thickness of the columnar crystal on the outermost surface of the intermediate layer is maintained as much as possible to the interface between the metal substrate and the intermediate layer. When the negative bias voltage is a low value, the columnar diameter of the columnar crystal is small, and when the negative bias voltage is high, the column diameter is large. In the initial stage of forming the intermediate layer, it is only necessary to start the film formation with a low bias voltage so as not to deteriorate the roughness of the interface with the base material, and then shift the bias voltage to a high value to grow the columnar crystals thickly. . Here, the roughness (Ra) of the interface with the base material due to the low bias voltage at the initial stage when forming the intermediate layer is set to a high bias voltage (for example, about 200 V (absolute value)) from the beginning. Since the energy applied to the surface increases, the roughness (Ra) of the interface of the metal substrate (for example, Al separator) is usually 0.5 or more, but at a low bias voltage (for example, about 50 V), 0.1 The roughness (Ra) of the interface can be reduced to the following, and adhesion failure does not occur. However, after the columnar crystal grows thick, the columnar crystal continues to grow thick even if the bias voltage is restored. Therefore, the conductive carbon film grows with the column diameter of the columnar crystals in the intermediate layer. In particular, it is desirable that the thickness of the columnar crystal on the outermost surface of the intermediate layer is maintained as much as possible up to the interface between the metal substrate and the intermediate layer. Film formation is started with a voltage, and then the thickness of the columnar crystals on the outermost surface of the intermediate layer is as much as possible by setting the bias voltage high enough to grow the columnar crystal diameter of the intermediate layer as thick as possible. And an intermediate layer maintained up to the interface between the intermediate layer and the intermediate layer. Here, if the magnitude (absolute value) of the high bias voltage is in the range of 50V to 500V, preferably 100 to 250V, the above characteristics can be effectively expressed.

(Manufacturing method of the second embodiment)
Another method for producing the conductive member of the present invention is characterized in that after the surface of the metal substrate is subjected to a polishing treatment, a coating treatment for forming a film on the surface of the substrate by a sputtering method is performed. (The second embodiment).

The method for producing a conductive member according to this embodiment is characterized in that after the surface of the metal substrate is subjected to a polishing treatment, a coating treatment is performed to form a film on the surface of the substrate by a sputtering method. In the manufacturing method according to the second embodiment, when the substrate roughness is reduced by polishing, the number of columnar crystal nucleation sites is reduced, and the column diameter of each columnar crystal can be increased.

  Here, the roughness (Ra) of the interface with the base material is usually 0.5 or more for a metal base material (for example, an Al separator or the like) without polishing, but is 0.4 or less, preferably 0.1. The interface roughness (Ra) can be reduced to the following.

  As the polishing treatment, generally implemented items can be widely adopted. For example, in addition to electrolytic polishing, lapping processing, microshot processing, and the like can be used. Needless to say, the manufacturing method of the first embodiment and the manufacturing method of the second embodiment may be combined.

  When the substrate roughness is reduced by the polishing treatment, the number of columnar crystal nucleation sites decreases, and the column diameter of each columnar crystal increases. As the polishing treatment, generally implemented items can be widely adopted. For example, in addition to electrolytic polishing, lapping processing, microshot processing, and the like can be used. Needless to say, the manufacturing method of the first embodiment and the manufacturing method of the second embodiment may be combined.

  However, the production method of the present invention is not limited to the first and second embodiments described above. In addition, as a method for increasing the columnar crystal column diameter, which is the original object of the present invention, A method for increasing the pressure of the columnar crystal and a method for increasing the film forming temperature may be adopted, and these may be appropriately combined to control the columnar crystal to have a larger column diameter.

  The above is an explanation of the main features of the manufacturing method of the first and second embodiments, and other manufacturing methods (processes, etc.) can be manufactured by appropriately referring to conventionally known methods. is there. Hereinafter, although preferable embodiment for manufacturing an electroconductive member is described, the technical scope of this invention is not limited only to the following form. Various conditions such as the material of each component of the conductive member constituting the separator will be described in the section of the conductive member to be described later, and the description is omitted here.

  First, an aluminum plate, a titanium plate, a stainless plate, or the like having a desired thickness is prepared as a constituent material of the metal base 31. In the second embodiment, a polishing process is performed on the surface of the metal substrate as a pretreatment before cleaning (for example, lapping polishing is performed in Example 2). Subsequently, the surface of the constituent material of the prepared metal substrate 31 is degreased and washed using an appropriate solvent (for example, ethanol, ether, acetone, isopropyl alcohol, trichlorethylene, and a caustic agent). Examples of the treatment include ultrasonic cleaning. As conditions for ultrasonic cleaning, the processing time is about 1 to 10 minutes, the frequency is about 30 to 50 kHz, and the power is about 30 to 50 W.

Subsequently, the oxide film formed on the surface (both sides) of the constituent material of the metal base 31 is removed. Examples of the technique for removing the oxide film include an acid cleaning process, a dissolution process by applying a potential, or an ion bombardment process. Next, in the present invention, a conductive member having an intermediate layer 32 in the form shown in FIG. In order to manufacture (separator), the step of forming the intermediate layer 32 on at least one main surface, preferably both surfaces, of the metal base 31 before the film forming step of the conductive carbon layer 33 described above is performed. Do. At this time, as a method for forming the intermediate layer 32, a method similar to that described later for forming the conductive carbon layer 33, preferably a dry film forming method, can be employed. However, it is necessary to change the target to the constituent material of the intermediate layer 32.

  In particular, in the present invention, a method of changing the negative bias voltage at the time of forming the intermediate layer 32 from a low value to a high value by the dry film forming method is suitable (first embodiment). Specifically, at the initial stage when forming the intermediate layer 32 as in Example 1 described later, a low bias voltage (exceeding 0V, exceeding 0V may be used so as not to deteriorate the roughness of the interface with the base material 31). About 50V, and 50 V in Example 1). After that, the magnitude (absolute value) of the bias voltage is set to a high value (usually 50 to 500V, preferably about 100 to 250V, in Example 1). The columnar crystal structure of the intermediate layer 32 can be controlled through preliminary experiments and the like. In the initial stage of forming the intermediate layer 32, the film formation may be started at a low bias voltage so as not to deteriorate the roughness of the interface with the base material 31. For example, the film is initially set to more than 0V to 50V, and then, for example, , 120V⇒90V⇒200V, there is no problem even if there is a region that changes from a high value to a low value (absolute value) (see FIGS. 20A to 20F, the magnitude of the bias voltage in the figure is absolute) Value.) This is because the column diameter of the columnar crystals is small when the bias voltage is low, and the column diameter is large when the bias voltage is high. In the initial stage of forming the intermediate layer 32, the film formation is started at a low bias voltage so as not to deteriorate the roughness of the interface with the substrate 31, and then the bias voltage is shifted to a high value to grow the columnar crystal structure thickly. Because. And the conductive carbon layer 33 grows with the thick columnar crystal structure which the intermediate | middle layer 32 has (refer FIG. 3B, SEM photograph of an Example). In the manufacturing method of the first embodiment, the intermediate layer 32 having the feature of the present invention has a columnar crystal structure as described above by a simple method of changing the set value of the apparatus, and a conductive member (conductive A conductive member having a structure in which the protruding particles 33a are present on the outermost surface of the carbon layer 33) can be obtained. In particular, the intermediate layer 32 starts the formation of the intermediate layer 32 on the metal substrate 31 at a low bias voltage first. If the energy applied to the surface is increased with a high bias voltage in order to thicken the column from the beginning, adhesion failure may occur. Therefore, it is preferable to manufacture the intermediate layer 32 while controlling the bias so that the thickness of the columnar crystal structure on the metal substrate 31 side is thinner than that on the conductive carbon layer 33 side. Therefore, as in the present invention, in the initial stage of forming the intermediate layer 32, it is preferable to start the film formation with a low bias voltage so as not to deteriorate the roughness of the interface with the base material. However, the thickness of the columnar crystals of the intermediate layer 32 thereafter is such that the columnar crystal structure is as thick as possible up to the outermost surface on the conductive member (conductive carbon layer 33) side, and the conductive carbon layer 33 and the intermediate layer 32 are as thick as possible. It is desirable to maintain up to the interface. Therefore, the bias voltage is subsequently shifted to a high value, and the column diameter of the columnar crystal is increased. The conductive carbon layer 33 grows while maintaining the column diameter of the columnar crystal of the intermediate layer 32. By the manufacturing method in the first and second embodiments, the column diameter (columnar diameter) of the columnar crystal of the intermediate layer 32 is increased to the interface with the conductive carbon layer 33, and the conductive carbon layer 33 formed thereon is formed. Gaps and defects can be reduced. As a result, the protruding particles 33a having a diameter of 200 to 500 nm in the outermost layer of the conductive member are due to the development of the column diameter of the columnar crystals of the intermediate layer 32, and the conductive member (conductive carbon layer 33) The number of gaps in the outermost layer is reduced, and a function of suppressing water intrusion can be provided. Therefore, the anticorrosion effect of the metal substrate 31 can be enhanced, and a manufacturing method that can be applied as a separator substrate can be established even in the case of a metal that is easily corroded, such as aluminum.

In the step of forming the intermediate layer 32 using the method of changing the negative bias voltage from a low value to a high value after polishing the surface of the metal base 31 described above, the intermediate layer 32 is formed by sputtering. It is preferable to perform a method (a coating process for forming a film) to form by a method. The structure of the present invention (for example, a conductive member in which an intermediate layer 32 is provided on a metal base 31 and a conductive carbon layer 33 is coated thereon, and the intermediate layer 32 has a columnar crystal structure. And a structure in which protruding particles 33a having a diameter of 200 to 500 nm and particles of 50 to 100 nm are mixed on the outermost surface, and further, there are at least 30 protruding particles 33a per 100 μm ^2. In order to form a conductive member composed of the metal base 31 having the structure), the intermediate layer 32, and the conductive carbon layer 33, the conductive carbon layer 33 is preferably a sputtering method, and is performed before the process. This is because the intermediate layer 32 is preferably formed by a similar dry process, particularly a sputtering method. Such an intermediate layer 32 makes it possible to form the conductive carbon layer 33 without poor adhesion, so that high conductivity and corrosion resistance can be obtained. Further, since the film can be formed in the same manner as the conductive carbon film, the manufacturing process cost can be reduced.

  Further, even in the step of forming the intermediate layer 32 using the method of changing the negative bias voltage from a low value to a high value, the surface of the metal base 31 is subjected to a pretreatment such as a polishing process, It is desirable to perform a coating process for forming a film on the surface of 31 by sputtering. This is because when the substrate roughness is reduced by the polishing treatment, the number of columnar crystal nucleation sites decreases, and the column diameter of each columnar crystal increases. Here, as the pre-treatment, in addition to the polishing treatment, generally implemented items can be widely adopted. For example, electrolytic polishing, lapping treatment, microshot treatment, etc. can be applied.

  Next, the intermediate layer 32 and the conductive carbon layer 33 are sequentially formed on the surface of the constituent material of the metal base 31 subjected to the above treatment. For example, using the constituent material of the intermediate layer 32 (for example, chromium) and the constituent material of the conductive carbon layer 33 (for example, graphite) in this order as targets, both the surfaces of the metal base 31 are first subjected to the bias change described above. By controlling the crystal structure of the intermediate layer 32 and increasing the column diameter of the columnar crystals, the intermediate layer 32 is formed by depositing (depositing) the chromium intermediate layer 32 and the layer 33 containing conductive carbon at the atomic level. 32 and the conductive carbon layer 33 can be formed sequentially. Thereby, the adhesion between the directly attached conductive carbon layer 33, intermediate layer 32, and metal substrate 31 and its vicinity can be maintained for a long period of time due to intermolecular forces and the entry of slight carbon atoms.

  As a method suitably used for laminating (depositing) the intermediate layer 32 and the conductive carbon layer 33, as a dry deposition method, for example, physical vapor deposition (PVD) such as a sputtering method or an ion plating method is used. Or ion beam deposition such as filtered cathodic vacuum arc (FCVA) method. Examples of the sputtering method include a magnetron sputtering method, an unbalanced magnetron sputtering (UBMS) method, a dual magnetron sputtering method, and an ECR sputtering method. Examples of the ion plating method include an arc ion plating method. Among these, it is preferable to use a sputtering method and an ion plating method, which are dry film forming methods, and it is particularly preferable to use a sputtering method. According to such a method, a carbon layer with a low hydrogen content can be formed. As a result, the ratio of bonds between carbon atoms (sp2 hybrid carbon) can be increased, and excellent conductivity can be achieved. In addition to this, the film can be formed at a relatively low temperature, and there is an advantage that damage to the metal substrate 31 can be minimized. Further, according to the sputtering method, by controlling the bias voltage or the like, the intermediate layer 32 has a columnar crystal structure with a column diameter having a thickness controlled as in the configuration of the present invention as described above. There is also an advantage that the film quality of each layer to be formed can be controlled.

  Here, when the intermediate layer 32 and the conductive carbon layer 33 are formed by the sputtering method, which is a dry film formation method, as described above, when a negative bias voltage is applied to the metal substrate 31 during the sputtering. Good. According to such a form, the intermediate of the structure having a columnar crystal structure having a controlled thickness as in the intermediate layer 32 of the present invention described above or a structure in which graphite clusters are densely assembled due to the ion irradiation effect. The layer 32 and the conductive carbon layer 33 can be formed. Such an intermediate layer 32 can enhance the anticorrosion effect of the metal substrate 31 and can be applied as the metal substrate 31 of the separator even in the case of an easily corroded metal such as aluminum, and the conductive carbon layer 33 is excellent. Since conductivity can be exhibited, a conductive member (separator) having low contact resistance with another member (for example, MEA) can be provided. In this embodiment, the magnitude (absolute value) of the negative bias voltage to be applied is not particularly limited, and a voltage capable of forming the conductive carbon layer 33 can be adopted. As an example, the magnitude of the applied voltage is preferably 50 to 500V, more preferably 100 to 300V. On the other hand, for the intermediate layer 32, as described above, a method of changing the negative bias voltage at the time of forming the intermediate layer 32 from a low value to a high value is suitable. Specifically, at the initial stage when the intermediate layer 32 is formed as in the examples described later, a low bias voltage (over 0 V, over 0 V to prevent the roughness of the interface with the base material 31 from being deteriorated). 50 V), and then the bias voltage is shifted to a high value (usually 50 to 500 V, preferably 100 to 250 V) to grow the columnar crystal structure thickly. The columnar crystal structure can be controlled. As described above, at the initial stage when the intermediate layer 32 is formed, the film formation may be started with a low bias voltage (may be higher than 0 V) so as not to deteriorate the roughness of the interface with the base material 31. For example, there is no problem even if there is a region where the value changes from a high value to a low value such as 120 V → 90 V → 200 V after that, for example, from 0V to 50V. This is because the column diameter of the columnar crystals is small when the bias voltage is low, and the column diameter is large when the bias voltage is high. In the initial stage of forming the intermediate layer 32, the film formation is started at a low bias voltage so as not to deteriorate the roughness of the interface with the base material, and then the bias voltage is shifted to a high value to grow the columnar crystal structure thickly. It is. The conductive carbon layer (film) 33 can be grown with the thick columnar crystal structure of the intermediate layer 32.

  In addition, specific forms, such as other conditions at the time of film-forming of the intermediate | middle layer 32 and the conductive carbon layer 33, are not restrict | limited, A conventionally well-known knowledge can be referred suitably. Further, when the conductive carbon layer 33 is formed by the UBMS method, it is preferable to form the intermediate layer 32 in advance by the same apparatus and manufacturing method, and form the conductive carbon layer 33 thereon. Thereby, the intermediate | middle layer 32 and the conductive carbon layer 33 which are excellent in adhesiveness with a base layer can be formed. However, the intermediate layer 32 may be formed by other methods, and the conductive carbon layer 33 may be formed by a different apparatus or manufacturing method. Even in this case, the intermediate layer 32 and the conductive carbon layer 33 having excellent adhesion to the metal substrate 31 can be formed.

According to the above-described method, a conductive member in which the intermediate layer 32 and further the conductive carbon layer 33 are formed on both surfaces of the metal base 31 can be manufactured. In order to manufacture a conductive member in which the intermediate layer 32 and further the conductive carbon layer 33 are formed on both surfaces of the metal base 31, a commercially available film forming apparatus (double-sided simultaneous sputter film forming apparatus and this was used. Sputter film formation method) may be used, or separately, a sputtering apparatus or a film forming apparatus capable of forming the intermediate layer 32 and further the conductive carbon layer 33 on both surfaces of the metal substrate 31 is formed and subjected to film formation. There are no particular restrictions. Although not advantageous in terms of cost, an intermediate layer 32 and further a conductive carbon layer 33 are formed on one main surface of the metal substrate 31, and then the other main surface of the metal substrate 31. On the other hand, the intermediate layer 32 and the conductive carbon layer 33 may be sequentially formed by the same method as described above. Alternatively, first, an intermediate layer 32 is formed on one main surface of the metal base 31 in an apparatus targeting a metal material such as chromium, and then the intermediate layer 32 formed by the above process is opposed. The intermediate layer 32 is formed on the main surface different from the main surface to be formed. Subsequently, the target is switched to carbon, and the conductive carbon layer 33 is formed on the intermediate layer 32 formed on one main surface of the metal base 31 in the same apparatus, and subsequently formed by the above process. What is necessary is just to perform the process of forming the conductive carbon layer 33 on the main surface different from the main surface opposite to the main surface different from the main surface facing the formed conductive carbon layer 33. As described above, even when the intermediate layer 32 is formed on both surfaces of the metal substrate 31 or the conductive carbon layer 33 is formed on the surface of the intermediate layer 32, the intermediate layer 32 on one surface of the metal substrate 31 may be used. There is no particular limitation such that the same method as described above (however, the number of man-hours can be halved) can be adopted for the formation of the layer 32 and the conductive carbon layer 33.
(Conductive member)
The conductive member of the present invention (which is a conductive member obtained by the manufacturing method of the first and second embodiments) includes a metal base and an intermediate layer on the metal base, and the intermediate A conductive member in which a conductive carbon layer is coated on a layer, wherein the intermediate layer has a columnar crystal structure, and protruding particles are present on the outermost surface of the conductive member. To do. This is because the fuel cell separator having a conductive carbon layer provided by a conventional technique has various crystal structures. Therefore, if the crystal structure of such a conductive carbon layer is different, the corrosion resistance and conductivity of the separator itself can be greatly varied due to this (it becomes difficult to control stably). However, in any case, the metal separator for a fuel cell provided by the conventional technology still has sufficient corrosion resistance and conductivity even if it is subjected to a surface treatment such as arrangement of a conductive carbon layer. It could not be said that the sex was secured. Therefore, in the present invention, when applying a corrosive metal substrate such as aluminum to the metal separator (conductive member), the thickest columnar structure crystal of the intermediate layer is the most effective measure for enhancing its anticorrosion function. It becomes the characteristic of. As one of the features appearing at that time, there is a protrusion shape on the intermediate layer and further on the outermost surface of the conductive member (see the table of examples and SEM photograph). On the other hand, in the conventional manufacturing method, there is no protrusion shape (see the comparative example table and SEM photograph). Therefore, the present invention is characterized by the presence of the protrusion particles, and the number of protrusion particles is sub- Claims.

  Thus, according to the configuration of the conductive member of the present invention, an intermediate layer is provided between the conductive carbon layer and the metal substrate, and the columnar crystal column diameter of the intermediate layer is extended to the interface with the conductive carbon layer. By making it thick (controlling the columnar crystal structure of the intermediate layer), it is an epoch-making thing that can reduce gaps and defects in the conductive carbon layer formed thereon. Furthermore, the protruding particles present in the outermost layer are caused by the development of the column diameter of the columnar crystals in the intermediate layer, and the number of gaps in the outermost layer is reduced, thereby providing a function of suppressing water intrusion. . As a result, the anticorrosion effect of the metal substrate can be enhanced, and while being lightweight and inexpensive like aluminum, it can be stably applied as a separator substrate for a long time even in the case of a metal that is easily corroded. That is, by increasing the column diameter of the columnar crystals in the intermediate layer (by controlling the column diameter), the gaps in the intermediate layer and the defects of the conductive carbon film existing thereon are reduced, preventing water from entering. By doing so, it can be said that the oxidation at each interface can be suppressed and the increase in contact resistance can be suppressed.

  That is, in the conductive member of the present invention, by applying the above manufacturing method, an intermediate layer is provided between the conductive carbon layer and the metal substrate, the columnar crystal structure of the intermediate layer is controlled, and the columnar column of the columnar crystal is formed. By increasing the diameter to the interface with the conductive carbon layer, columnar protrusions (convex portions) are formed on the surface of the intermediate layer. By forming a conductive carbon layer thereon, a conductive carbon layer having an outermost surface having undulations (columnar protrusion shape: convex portions = protruding particles) along the undulations (columnar protrusion shape) on the surface of the intermediate layer Can be formed. As a result, a conductive member having a structure in which the intermediate layer has a columnar crystal structure and the protruding particles are present on the outermost surface of the conductive member is provided. In such a conductive member, by increasing the column diameter of the columnar crystals of the intermediate layer so that the protruding particles are present on the outermost surface, the gaps between the columnar crystals of the intermediate layer and the gaps in the conductive carbon layer existing thereon are provided. And greatly reduce defects. That is, the protruding particles are caused by the development of the columnar diameter of the intermediate layer, and the number of gaps in the outermost layer is reduced, and a function of suppressing water intrusion can be provided. As a result, it is possible to suppress oxidation at each interface, suppress an increase in contact resistance while sufficiently ensuring excellent conductivity, enhance the anticorrosion effect of the metal substrate, and easily corrode metals such as aluminum Even in this case, it can be applied as a base material of a separator.

  Embodiments to which the present invention is applied will be described below with reference to the accompanying drawings. In addition, this invention is not restrict | limited only to the following embodiment. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

  FIG. 1 shows a basic configuration of a fuel cell using a metal separator, which is a typical embodiment of a conductive member according to the present invention, specifically a basic configuration of a cell unit of a polymer electrolyte fuel cell (PEFC). FIG. FIG. 2 is a partial cross-sectional view showing an outline of a layer for surface treatment formed on the substrate surface of the metal separator of FIG. 1, which is a typical embodiment of the conductive member according to the present invention.

  In the cell unit 1 of the fuel cell (PEFC) shown in FIG. 1, catalyst layers 3 (3a for an anode and 3b for a cathode) are disposed on both surfaces of a solid polymer electrolyte membrane 2. The laminate of the solid polymer electrolyte membrane 2 and the catalyst layer 3 (3a, 3b) is further provided with a gas diffusion layer 4 (anode 4a and cathode 4b) so as to sandwich them, A membrane electrode assembly (MEA) 9 is formed. The MEA (Mebrane Electrode Assembly) 9 is finally sandwiched by a pair of conductive metal separators 5 (anode 5a and cathode 5b) to form a single cell unit 1 of PEFC. In FIG. 1, the metal separator 5 (the anode 5 a and the cathode 5 b) is illustrated so as to be located on both surfaces (both sides) of the MEA 9. However, in a fuel cell stack in which a plurality of MEAs 9 are stacked, the metal separator 5 is generally used as the metal separator 5 for the adjacent PEFC cell unit 1 (see FIGS. 11 and 12). In other words, in the fuel cell stack, the MEAs 9 are sequentially stacked via the metal separator 5 to constitute a stack. In an actual fuel cell stack, between the metal separator (5a, 5b) and the solid polymer electrolyte membrane 2, or between the PEFC cell unit 1 and another adjacent PEFC cell unit 1. Although the gas seal portion is arranged, these descriptions are omitted in FIG. 1 (see FIGS. 11 and 12).

The convex part seen from the MEA 9 side of the metal separator 5 (5a, 5b) is in contact with the MEA 9. Thereby, the electrical connection with MEA9 is ensured. In addition, the concave portion (the space between the metal separator 5 and the MEA 9 generated due to the uneven shape of the metal separator 5) viewed from the MEA 9 side of the metal separator 5 (5a, 5b) is a gas during the operation of the PEFC 1. It functions as a gas flow path for circulating. Specifically, a fuel gas 5ag (for example, hydrogen or a hydrogen-containing gas) is circulated through the gas flow path 5aa of the anode separator 5a, and an oxidant gas 5bg (for example, air) is passed through the gas flow path 5bb of the cathode separator 5b. Or gas containing O ₂ ).

  On the other hand, the recess viewed from the side opposite to the MEA 9 side of the metal separator 5 (5a, 5b) is a refrigerant for circulating a refrigerant 8w (for example, cooling water, water) for cooling the PEFC during operation of the PEFC 1. The channel 8 is used. Further, the metal separator 5 (5a, 5b) is usually provided with a manifold (not shown). This manifold functions as a connecting means for connecting each cell (unit 1) of the PEFC when a stack is formed. With such a configuration, the mechanical strength of the fuel cell stack 200 can be ensured (see FIGS. 11 and 12).

In an actual fuel cell (PEFC), a gas seal is provided between the metal separator 5 and the periphery (periphery) of the end of the electrolyte membrane 2 and between the cell unit 1 of the fuel cell and another cell unit 1 adjacent thereto. Arranged but not shown in this schematic diagram. The separator 5 for a fuel cell is a metal separator 5 that is an embodiment of the conductive member according to the present invention. For example, by pressing a thin plate having a thickness of 0.5 mm or less, unevenness as shown in FIGS. Are formed into a gas flow path 5aa, 5bb and a refrigerant flow path 8 in the shape of a wave, and a fuel gas 5ag (hydrogen or hydrogen-containing gas) or an oxidant gas 5bg (air) is formed there (gas flow paths 5aa, 5bb). Or O ₂ containing gas) or cooling water 8w.

  As described above, in addition to the function of electrically connecting each MEA 9 in series, the metal separator 5 has gas flow paths 5aa, 5bb and refrigerant flow through which different fluids such as the fuel gas 5ag, the oxidant 5bg gas, and the refrigerant 8w flow. A path 8 and a manifold are provided, and further, there is a function of maintaining the mechanical strength of the stack. Since the electrolyte membrane 2 is usually a perfluorosulfonic acid type membrane, various acidic ions eluted from the membrane and a humidified gas are introduced into the battery. In the environment.

  For this reason, as shown in FIG. 2, the surface treatment of the metal separator 5 requires not only conductivity but also corrosion resistance. It is essential that the surface treatment layer 7 disposed on the metal base 6 of the metal separator 5 is applied to the reaction surface 7a having severe corrosion conditions, but the reaction surface 7a is a cooling surface 7b on the back side. However, the same processing is required depending on the type and environment of the cooling medium 8w.

3A is a partial cross-sectional view showing the configuration and arrangement of each layer for surface treatment formed on the surface of a metal substrate of a metal separator that is an embodiment of the conductive member of FIGS. It is a simplified diagram for explaining functions required for each layer. FIG. 3B is an enlarged view in which a part of FIG. 3A is enlarged to further clarify the configuration of an intermediate layer having a thick columnar crystal structure and a conductive carbon layer in which protruding particles exist on the outermost surface. is there. FIG. 3C shows, in contrast to FIG. 3B, the metal substrate of the separator used in the fuel cell unit, the intermediate layer having a thin needle-like crystal structure, and the conductive carbon layer having no protruding particles on the outermost surface. It is the enlarged view which clarified the structure more. In FIG. 3B, H ₁ , H ₂ , H ₃ ,... Indicate the height of the protruding particles on the outermost surface of the conductive carbon layer 33 (projection height), and W ₁ , W ₂ , W ₃ ,. The thickness (column diameter, width) of the columnar crystal structure in the intermediate layer 32 is indicated. Reference numeral 33 a in FIG. 3B indicates the protruding particles on the outermost surface of the conductive carbon layer 33. On the other hand, in FIG. 3C, there is no protruding particle 33 a on the outermost surface of the conductive carbon layer 33, and the protrusion height H (H ₁ , H ₂ , H ₃ ,...) Greater than a predetermined size and the thickness of the columnar crystal. The length W (W ₁ , W ₂ , W ₃ ,...) Represents a state where it is not formed.

  In this embodiment shown in FIG. 3A, the conductive members constituting the metal separator 5 are a metal base 31 (reference numeral 6 in FIG. 2) and a conductive carbon layer 33 (part of reference numeral 7 in FIG. 2: outer portion). And have. And between these, the intermediate | middle layer 32 (a part of code | symbol 7 of FIG. 2: inside part) is interposing. In the PEFC cell unit 1, the metal separator 5 is disposed so that the conductive carbon layer 31 is located on the MEA 9 side (see FIGS. 2, 11, and 12).

  As shown in FIG. 3, as a cross-sectional configuration of the metal separator 5 of the fuel cell (PEFC) which is a typical embodiment of the conductive member according to the present invention, both main surfaces of the metal base 31 of the metal separator 5 ( The intermediate layer 32 and the outermost conductive carbon layer 33 are disposed on the surface). When stainless steel with excellent corrosion resistance such as SUS316L is used for the metal substrate 31, the metal substrate 31 itself can withstand the corrosive environment in the fuel cell. Not strict. However, from our test results, in order to further promote the reduction in thickness and cost, when the metal base 31 is made of aluminum that is superior in thickness and weight than stainless steel, the aluminum itself has poor corrosion resistance, so the crystal of the intermediate layer 31 It has been found that the above problems (such as anticorrosion means) can be solved by controlling the structure.

  The corrosion of the metal base material 31 of the metal separator 5 depends on the weak acid (acidity) in the battery and the surface potential of the metal separator 5. For this reason, when the corroded aluminum or its alloy is used as the metal substrate 31 of the metal separator 5, it is necessary to prevent corrosion against acidity and potential. However, since corrosion itself occurs for the first time due to the presence of water, a surface treatment that prevents the aluminum of the metal base 31 or its alloy from coming into contact with water as much as possible will take the root of the corrosion, and its effect is extremely high. Big. For this reason, even when defects such as pinholes occur in the conductive carbon layer 33 as the outermost layer, the intermediate layer 32 is formed (formed) by a manufacturing method so that the crystal structure of the intermediate layer 32 can be controlled. The penetration of water into the following separator can be suppressed. As a result, it has been found that the expected excellent battery performance can be stably expressed and maintained for a long time.

  Hereinafter, each component of the metal separator 5 of this embodiment is explained in detail.

[Metal base material]
The metal substrate 31 is a main layer of a conductive member that constitutes the metal separator 5 and contributes to securing conductivity and mechanical strength.

  There is no restriction | limiting in particular about the metal which comprises the metal base material 31, The thing conventionally used as a constituent material of the metal separator 5 can be used suitably. Examples of the constituent material of the metal base 31 include iron, titanium, aluminum, and alloys thereof. These materials can be preferably used from the viewpoint of mechanical strength, versatility, cost performance, or processability. Here, the iron alloy includes stainless steel. Especially, it is preferable that the metal base material 31 is comprised from stainless steel, aluminum, or an aluminum alloy. When stainless steel is used as the metal substrate 31, the conductivity of the contact surface with the gas diffusion substrate that is a constituent material of the gas diffusion layer (GDL) 4 can be sufficiently ensured. As a result, even if moisture enters the gaps between the rib shoulder film and the like, durability can be maintained by the corrosion resistance of the oxide film formed on the metal base 31 itself made of stainless steel. Here, GDL4 is composed of a portion where the surface pressure is directly applied to GDL4 (4a, 4b) (contact portion with metal separator 5; rib portion) and a portion which is not directly applied (portion portion not contacting; flow path portion). The rib shoulder portion refers to a contact portion with the metal separator 5; a shoulder portion (corner portion) of the rib portion.

  Examples of stainless steel include austenite, martensite, ferrite, austenite / ferrite, and precipitation hardening. Examples of austenite include SUS201, SUS202, SUS301, SUS302, SUS303, SUS304, SUS305, SUS316 (L), and SUS317. Examples of the austenite-ferrite type include SUS329J1. Examples of the martensite system include SUS403 and SUS420. Examples of the ferrite type include SUS405, SUS430, and SUS430LX. Examples of the precipitation hardening system include SUS630. Among these, it is more preferable to use austenitic stainless steel such as SUS304 and SUS316. Moreover, the content rate of iron (Fe) in stainless steel becomes like this. Preferably it is 60-84 mass%, More preferably, it is 65-72 mass%. Furthermore, the content of chromium (Cr) in the stainless steel is preferably 16 to 20% by mass, and more preferably 16 to 18% by mass.

  On the other hand, examples of the aluminum alloy include pure aluminum, aluminum / manganese, and aluminum / magnesium. The elements other than aluminum in the aluminum alloy are not particularly limited as long as they are generally usable as an aluminum alloy. For example, copper, manganese, silicon, magnesium, zinc and nickel can be included in the aluminum alloy. Specific examples of the aluminum alloy include A1050 and A1050P as the pure aluminum system, A3003P and A3004P as the aluminum / manganese system, and A5052P and A5083P as the aluminum / magnesium system. On the other hand, since the mechanical strength and formability are also required for the metal separator 5, in addition to the above alloy types, the tempering of the alloy can be selected as appropriate. In addition, when the metal base material 31 is comprised from the simple substance of titanium or aluminum, the purity of the said titanium or aluminum becomes like this. Preferably it is 95 mass% or more, More preferably, it is 97 mass% or more, More preferably, it is 99 mass % Or more.

  The thickness of the metal substrate 31 is not particularly limited. From the viewpoint of ease of processing and mechanical strength, and improvement of the energy density of the battery by thinning the separator 5 itself, it is preferably 50 to 500 μm, more preferably 80 to 300 μm, and still more preferably 80 ~ 200 μm. In particular, the thickness of the metal substrate 31 when stainless steel is used as the constituent material is preferably 80 to 150 μm. On the other hand, the thickness of the metal substrate 31 when aluminum is used as a constituent material is preferably 100 to 300 μm. In the above range, the metal separator 5 has a sufficient strength, but is excellent in workability and can achieve a suitable thickness.

  For example, from the viewpoint of providing sufficient strength as a constituent material for the fuel cell separator 5 or the like, the metal substrate 31 is preferably made of a material having a high gas barrier property. Since the separator 5 of the fuel cell plays a role of partitioning the cells, different gas flows on both sides of the separator 5 (see FIG. 11). Therefore, from the viewpoint of eliminating the mixing of adjacent gases in each cell of the PEFC cell unit 1 and the fluctuation of the gas flow rate, the higher the gas barrier property, the more preferable the metal substrate 31 is.

[Conductive carbon layer]
The conductive carbon layer 33 is a layer containing conductive carbon. The presence of this layer can improve the corrosion resistance as compared with the case of only the metal substrate 31 while ensuring the conductivity of the conductive member constituting the metal separator 5.

In the present embodiment, the conductive carbon layer 33 has an intensity ratio R (I _D / I _G ) between the D band peak intensity (I _D ) and the G band peak intensity (I _G ) measured by Raman scattering spectroscopy. It is prescribed by. Specifically, the intensity ratio R (I _D / I _G ) is 1.3 or more. Hereinafter, the configuration requirement will be described in more detail.

When the carbon material is analyzed by Raman spectroscopy, peaks are usually generated around 1350 cm ⁻¹ and 1584 cm ⁻¹ . Highly crystalline graphite has a single peak near 1584 cm ⁻¹ , and this peak is usually referred to as the “G band”. On the other hand, a peak near 1350 cm ⁻¹ appears as the crystallinity decreases (crystal structure defects increase). This peak is usually referred to as the “D band” (note that the peak of diamond is strictly 1333 cm ⁻¹ and is distinct from the D band). The intensity ratio R (I _D / I _G ) between the D band peak intensity (I _D ) and the G band peak intensity (I _G ) is the graphite cluster size of the carbon material and the disorder of the graphite structure (crystal structure defect), It is used as an indicator such as sp2 bond ratio. That is, in the present invention, it can be used as an index of the contact resistance of the conductive carbon layer 33 and can be used as a film quality parameter for controlling the conductivity of the conductive carbon layer 33.

The R (I _D / I _G ) value is calculated by measuring the Raman spectrum of the carbon material using a microscopic Raman spectrometer. Specifically, the peak intensity of 1300～1400Cm ^-1 called the D band _{(I D),} the relative intensity ratio of the peak intensity of 1500～1600Cm ^-1 called G band _{(I G)} (peak area ratio ( I _D / I _G )).

  As described above, in this embodiment, the R value is 1.3 or more. Moreover, in preferable embodiment, the said R becomes like this. Preferably it is 1.4-2.0, More preferably, it is 1.4-1.9, More preferably, it is 1.5-1.8. When the R value is 1.3 or more, the conductive carbon layer 33 in which the conductivity in the stacking direction is sufficiently secured is obtained. Moreover, if R value is 2.0 or less, the reduction | decrease of a graphite component can be suppressed. Furthermore, an increase in internal stress of the conductive carbon layer 33 itself can also be suppressed, and the adhesion to the metal base material 31 that is the base and further to the intermediate layer 32 can be further improved.

  In addition, the mechanism by which the above-mentioned effect is acquired by making R value 1.3 or more like this embodiment is estimated as follows. However, the following estimation mechanism does not limit the technical scope of the present invention in any way.

  As described above, increasing the D-band peak intensity (that is, increasing the R value) means an increase in crystal structure defects in the graphite structure. In other words, it means that the sp3 carbon increases in the highly crystalline graphite composed of almost only the sp2 carbon. Here, a photograph (magnification: 400,000 times) of a cross section of a conductive member (conductive member A) having a conductive carbon layer of R = 1.0 to 1.2 observed with a transmission electron microscope (TEM) is shown in FIG. 4A. Shown in Similarly, the photograph (magnification: 400,000 times) which observed the cross section of the electrically-conductive member (conductive member B) which has the conductive carbon layer of R = 1.6 by TEM is shown to FIG. 4B. Note that SUS316L was used as the metal base 31 for these conductive members A and B. This surface has an intermediate layer made of Cr, more specifically, a columnar crystal structure, and the projecting particles 33a (FIGS. 3B, 13B, 14B, 15B) on the outermost surface of the conductive member. ), FIG. 16 (b), and FIGS. 17 to 19. The same shall apply hereinafter.) The intermediate layer 32 (thickness: 0.2 μm) and the conductive carbon layer (thickness: 0.2 μm) are present. 33 was formed by sequentially forming by sputtering. Further, the bias voltage applied to the metal substrate 31 at the time of producing the conductive carbon layer in the conductive member A is 0 V, and is applied to the metal substrate 31 at the time of producing the conductive carbon layer in the conductive member B. The bias voltage applied was -140V. The intermediate layer 32 has a columnar crystal structure (see FIG. 3B, FIG. 13B, FIG. 14B, FIG. 15B, FIG. 16B, and FIGS. 17 to 19). In addition, protruding particles 33a (see FIGS. 3B, 13B, 14B, 15B, 16B, and 17 to 19) are present on the outermost surface of the conductive member. The intermediate layer 32 (thickness: 0.2 μm) is preferably formed by a dry film forming method, for example, a sputtering method or a spion plating method. According to the present invention, when the intermediate layer 21 is provided between the conductive carbon layer 33 and the metal substrate layer 31, the negative bias voltage in the dry film forming method is changed from at least a low value to a high value. By changing, the columnar crystal structure of the intermediate layer 32 is controlled, and the columnar protrusions (convex portions) are formed on the surface of the intermediate layer 32 by increasing the column diameter of the columnar crystals to the interface with the conductive carbon layer. Is done. By forming the conductive carbon layer 33 thereon, the conductive layer having the outermost surface having undulations (columnar protrusion shape: convex portion = protruding particles) along the undulation (columnar protrusion shape) of the surface of the intermediate layer 32. The carbon layer 33 can be formed. As a result, a conductive member having a structure in which the intermediate layer 32 has a columnar crystal structure and the protruding particles 33a exist on the outermost surface of the conductive member is provided. In such a conductive member, by increasing the column diameter of the columnar crystals of the intermediate layer 32 so that the protruding particles 33a exist on the outermost surface, the gap between the columnar crystals of the intermediate layer 32 and the conductive carbon present thereon are formed. The gaps and defects in the layer 33 are greatly reduced. That is, the protruding particles 33a are due to the development of the columnar diameter of the intermediate layer 32, and the number of outermost layer gaps can be reduced to provide a function of suppressing water intrusion. As a result, it is possible to suppress oxidation at each interface, to suppress an increase in contact resistance while sufficiently ensuring excellent conductivity, to enhance the anticorrosion effect of the metal base layer 31, and to corrode like aluminum. Even in the case of an easy metal, it is excellent in that it can be applied as the metal base layer 31 of the metal separator 5.

  As shown in FIG. 4B, it can be seen that the conductive carbon layer of the conductive member B has a structure of polycrystalline graphite. On the other hand, such a structure of polycrystalline graphite cannot be confirmed in the conductive carbon layer of the conductive member A shown in FIG. 4A.

  Here, “polycrystalline graphite” microscopically has an anisotropic graphite crystal structure (graphite cluster) in which graphene surfaces (hexagonal network surfaces) are laminated, but macroscopically, a large number of such graphite structures. Is an isotropic crystal. Therefore, it can be said that the polycrystalline graphite is one type of diamond-like carbon (DLC). Normally, single crystal graphite has a disordered structure in which graphene surfaces are laminated even when viewed macroscopically, as represented by HOPG (highly oriented pyrolytic graphite). On the other hand, the polycrystalline graphite has a graphite structure as an individual cluster, and has a turbostratic structure. By controlling the R value to the above-mentioned value, this degree of disorder (graphite cluster amount, size) can be ensured appropriately, and a conductive path from one surface of the conductive carbon layer 33 to the other surface can be secured. As a result, it is considered that a decrease in conductivity due to the separate provision of the intermediate layer 32 and the conductive carbon layer 33 in addition to the metal substrate 31 can be prevented. Further, in addition to the conductive carbon layer 33, the intermediate layer can be formed (manufactured) by controlling the crystal structure of the intermediate layer 32 between the metal base layer 31 and the conductive carbon layer 33. In the case where 32 is separately provided, it is possible to provide a means for suppressing an increase in contact resistance while sufficiently securing the excellent conductivity (holding the effect of preventing the decrease in conductivity). In the present embodiment, as described above, as a method of film formation (manufacturing) that can control the crystal structure of the intermediate layer 32, as described above, a method of changing the negative bias voltage at the time of forming the intermediate layer from at least a low value to a high value, Alternatively, after a polishing process is performed on the surface of the metal substrate, a coating process is performed in which a film is formed on the surface of the substrate by a sputtering method.

  In polycrystalline graphite, since the graphene surface is formed by the bonding of sp2 carbon atoms constituting the graphite cluster, conductivity is ensured in the plane direction of the graphene surface. Polycrystalline graphite is substantially composed of only carbon atoms, has a small specific surface area, and a small amount of bonded functional groups. For this reason, polycrystalline graphite has excellent resistance to corrosion by acidic water or the like. In addition, even in powders such as carbon black, primary particles are often formed by aggregates of graphite clusters, thereby exhibiting electrical conductivity. However, since the individual particles are separated, there are many functional groups formed on the surface, and corrosion due to acidic water or the like is likely to occur. In addition, even when a conductive carbon layer is formed with carbon black, there is a problem that the denseness as a protective film is lacking.

  Here, when the conductive carbon layer 33 of the present embodiment is made of polycrystalline graphite, the size of the graphite cluster constituting the polycrystalline graphite is not particularly limited. As an example, the average diameter of the graphite cluster is preferably about 1 to 50 nm, more preferably 2 to 10 nm. When the average diameter of the graphite cluster is within such a range, it is possible to prevent the conductive carbon layer 33 from being thickened while maintaining the crystal structure of the polycrystalline graphite. Here, the “diameter” of the graphite cluster means the maximum distance among the distances between any two points on the contour line of the cluster. Moreover, the average diameter value of the graphite cluster is expressed as an average value of the diameter of the cluster observed in several to several tens of fields using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Can be calculated.

In particular, in the present invention, as shown in FIG. 3B and the like, it is desirable to have protruding particles 33a having a diameter of 200 to 500 nm on the outermost surface of the conductive member (conductive carbon layer 33). More preferably, on the outermost surface of the conductive member, protruding particles 33a having a diameter of 200 to 500 nm and fine particles 33b of 50 to 100 nm (FIGS. 3B, 13B, 14B, and 15) b), FIG. 16B, and FIGS. 17 to 19) are particularly desirable. Conversely, as shown in FIG. 3C, there are no protruding particles 33a having a diameter of 200 to 500 nm on the outermost surface of the conductive member (conductive carbon layer 33), or about 10 particles per 100 μm ^2. However, when the conductive carbon layer 33 is composed of almost 50 to 100 nm fine particles 33b, the desired object of the present invention is not achieved, which is not desirable. . That is, as shown in FIG. 3C, the column diameter of the intermediate layer 32 is small, and there are relatively many gaps between the intermediate layers 32, and defects in the conductive carbon film 33 existing thereon cannot be sufficiently reduced. This is because it is difficult to effectively prevent the ingress of water, so that it is difficult to suppress oxidation at each interface and the increase in contact resistance cannot be sufficiently suppressed (see FIG. 3C and FIG. 3B of the present embodiment). (Refer to Comparative Example 1, 2 and Comparative Examples 1 and 2)

  On the other hand, in the present invention, by changing the negative bias voltage from at least a low value to a high value at the time of forming the intermediate layer 32 by the dry film forming method, as shown in FIG. An intermediate layer 32 is provided between the material 31, the crystal structure of the intermediate layer 32 is controlled, and the column diameter of the columnar crystal is increased (increased) to the interface with the conductive carbon layer 31. It is possible to reduce gaps and defects in the carbonaceous layer 33. Specifically, when the protruding particles 33a having a diameter of 200 to 500 nm, preferably 300 to 500 nm, more preferably 400 to 500 nm are present on the outermost surface (and the outermost layer), the column diameter (columnar diameter) of the intermediate layer 32 is present. ), The number of gaps in the outermost surface (and the outermost layer) is reduced, and a function of suppressing water intrusion can be provided. Further, in the peripheral part (so-called flat part having a small unevenness change amount) other than the projecting particles 33a having a diameter of 200 to 500 nm, fine particles 33b of 50 to 100 nm are present (mixed) and formed thereon. This is particularly effective in reducing gaps and defects in the conductive carbon layer 33 to be formed. With such a structure, it is possible to improve the anticorrosion function of the conductive carbon layer 33 while enhancing the anticorrosion function of the intermediate layer 32 to the metal substrate 31, and to reduce the thickness without reducing the coverage. . In particular, the anticorrosion effect of the metal substrate 31 can be enhanced, and even in the case of an easily corroded metal such as aluminum, the metal substrate 31 can be applied as a separator substrate. The diameter (200 to 500 nm) of the protruding particles 33a on the outermost surface (outermost layer) of the conductive member (conductive carbon layer 33) here refers to the range of particle size distribution. The measuring method of the diameter of the protruding particles 33a on the outermost surface (outermost layer) of the conductive member (conductive carbon layer 33) uses an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). It can be calculated as an average value of the diameters of clusters observed in several to several tens of fields (see the enlarged view of the SEM (surface) and SEM (cross section) observation drawings of the examples). Similarly, fine particles on the outermost surface (outermost layer) of the conductive member (conductive carbon layer 33) (so-called non-projection state: see enlarged view of observation drawing of SEM (surface) and SEM (cross section) of Example) The size of 33b (diameter: 50 to 100 nm) also refers to the range of particle size distribution. The measuring method of the size (diameter) of the fine particles 33b on the outermost surface (outermost layer) of the conductive member (conductive carbon layer 33) is also observed with a scanning electron microscope (SEM) or a transmission electron microscope (TEM). It can be calculated as an average value of the diameters of clusters observed in several to several tens of fields using a means (see enlarged views of observation drawings of SEM (surface) and SEM (cross section) of Examples). In particular, as a detailed description of the method for measuring the protruding particles 33a of the present invention, from a result of observation of the sample surface by SEM, a particle shape with a small contrast (white) having a particle size of 200 to 500 nm (range of particle size distribution) (See the enlarged view of the observation drawing of the SEM (surface) or SEM (cross section) of the example).

On the outermost surface of the conductive member (conductive carbon layer 33), the protruding particles 33a are present in a range of at least 30 or more, preferably 30 to 100, more preferably 50 to 80 per 100 μm ² . Is desirable. This is because, when the number of the protruding particles 33a is less than 30 per 100 μm ² , the development of the columnar crystal diameter of the intermediate layer 32 decreases, so that the columnar shape on the outermost surface (surface layer) of the conductive member (conductive carbon layer 33). This is because the number of gaps between crystals (also simply referred to as columnar shapes) increases, resulting in an increase in contact resistance. However, in the present invention, even if the number of the protruding particles 33a per 100 μm ² is less than 30, the number may be one or more as long as the intended effect of the present invention is not impaired. It may be included in the present invention. From the enlarged view of the SEM (surface) and SEM (cross section) of the comparative example, the number of the protruding particles 33a per 100 μm ² is 0 (none), and both (100 μm ^{2 of the} protruding particles 33a). This is because there may be a case where a significant difference occurs between the number of hits between 0 and 1 or more. By providing such a configuration, gaps in the intermediate layer 32 are reduced, and formation of an oxide film inside the surface treatment can be suppressed, so that an extremely useful and effective configuration (structure) such as an increase in contact resistance can be suppressed. )

  It is desirable that the proximity distance between the outermost protruding particles 33a be within 1 μm. With this configuration, when the distances between the outermost protruding particles 33a are dispersed within a range of 1 μm or less, the protruding particles 33a of claim 1 are uniformly formed in the plane. This is because the rust-preventing ability is improved. As a result, it is possible to improve the anticorrosion function of the conductive carbon layer while enhancing the anticorrosion function of the intermediate layer on the metal substrate, and to reduce the thickness without reducing the coverage.

  In the outermost surface of the conductive member (conductive carbon layer 33), the height (average value) of the protruding particles 33a on the outermost surface is 100 to 500 nm, preferably 300 to 500 nm, more preferably 300 with respect to the peripheral portion. It is desirable to project at ~ 400 nm. This is because, when the height (average value) of the protruding particles 33a is within the above range on the outermost surface of the conductive member (conductive carbon layer 33), the columnar crystals of the intermediate layer 32 formed grow, and the intermediate layer The gap in the intermediate layer 32 is further reduced, and the anticorrosion function of the metal substrate 31 can be further improved. Further, when the outermost surface of the conductive member (conductive carbon layer 33) has a protruding shape (convex shape) in which the protruding particles 33a are present, the specific surface area is improved and the hydrophilic surface is more hydrophilic. Since the degree is increased, the wettability of the surface is also improved. To explain this point in more detail, in general, when hydrophilicity is shown, when the static contact angle of water droplets on the sample surface is 90 degrees or less, when the hydrophilic surface has fine irregularities, hydrophilicity Is known to improve. When the hydrophilicity of the surface is improved, the drainage property is improved, so that a decrease in gas diffusibility due to a flooding phenomenon can be suppressed.

  Here, the average value by the following measuring method shall be used for the height (average value) with respect to the peripheral part of the outermost protruding particles 33a. In addition, terms and measurement methods used in the present invention will be described as collectively as possible below (some terms and measurement methods may be described in some parts of the examples and specification).

I. Regarding the Intermediate Layer (a) The columnar crystal structure refers to a structure in which crystals constituting the intermediate layer are grown in a columnar shape in the film thickness direction.

  (B) About the measuring method of the average value of the column thickness of the columnar crystal in the cross section of the intermediate layer, the columnar crystal growing in the direction perpendicular to the base material is confirmed by the contrast from the cross-sectional observation result by TEM. It can be obtained by specifying one column from the interface of the column and calculating the distance of the interface from the interface in the direction parallel to the base material.

  (C) The thickness of the columnar crystal in the cross section of the intermediate layer is 200 to 500 nm, and the columnar crystal having the thickness is the intermediate layer thickness (average on the conductive carbon layer side of the entire intermediate layer. Value) For the method of measuring what percentage of the total, the thickness of the column at the depth before the protrusion shape on the surface side appears from 50% of the thickness of the intermediate layer using the above thickness measurement method. It can be obtained by measuring the thickness.

  (D) In the entire intermediate layer, the conductive carbon layer side refers to a region present in 50% of the conductive carbon side of the intermediate layer thickness.

  (E) The measuring method of the film thickness (average value) of the intermediate layer can be read from the SEM cross section or the cross-sectional observation result by TEM.

II. About the outermost surface of the conductive carbon layer (conductive member) (a) The protruding particles 33a having a diameter of 200 to 500 nm on the outermost surface are covered with the conductive carbon layer and inherited from the intermediate layer. A columnar crystal having a column diameter of 200 to 500 nm is observed in the form of particles on the outermost surface.

  (B) The microparticles 33b having a diameter of 50 to 100 nm are coated on the surface with a conductive carbon layer, and a column having a columnar crystal diameter of 200 to 500 nm inherited from the intermediate layer is a particle on the outermost surface. This means that the undulations on the surface such as the protruding particles are small.

  (C) The height (average value) of the protruding particles 33a having a diameter of 200 to 500 nm is that the surface is coated with a conductive carbon layer, and the columnar structure of the intermediate layer is pyramidal (Kenyama) The height from the part starting to become the shape to the tip.

  (D) About the measuring method of the diameter of the protruding particle 33a, one particle is picked up from the contrast confirmed from the surface observation by SEM, and it can obtain | require by the average diameter of the particle | grain.

(E) About the measuring method of the height (average value) (also simply referred to as the protrusion height) of the protruding particles 33a, the columnar structure of the intermediate layer has a pyramid shape (sword mountain shape) on the outermost surface from cross-sectional observation by TEM. It can be determined by the height from the part starting to become the tip part,
(F) As for the specific method of the reference surface of the protrusion height (peripheral part of the protrusion particle 33a on the outermost surface), the columnar structure of the intermediate layer starts to become pyramid (sword mountain shape) on the outermost surface To do.

(G) About the measuring method of the number of the protruding particles 33a having a diameter of 200 to 500 nm per 100 μm ^{2, the} particles that are confirmed to be white as contrast by surface observation by SEM are regarded as protruding particles, and 100 μm ² can be obtained by measuring the number of particles present in ² ;
(I) About the measuring method of the microparticles 33b with a diameter of 50-100 nm, it can obtain | require by the maximum diameter of 1 particle by surface observation by SEM.

  In the present embodiment, the conductive carbon layer 33 may be composed of only polycrystalline graphite, but the conductive carbon layer 33 may include materials other than polycrystalline graphite. Examples of carbon materials other than polycrystalline graphite that can be included in the conductive carbon layer 33 include carbon black, fullerene, carbon nanotubes, carbon nanofibers, carbon nanohorns, and carbon fibrils. Specific examples of carbon black include, but are not limited to, ketjen black, acetylene black, channel black, lamp black, oil furnace black, or thermal black. Carbon black may be subjected to a graphitization treatment. Examples of materials other than the carbon material that can be included in the conductive carbon layer 33 include gold (Au), silver (Ag), platinum (Pt), ruthenium (Ru), palladium (Pd), rhodium (Rh), and indium. Examples thereof include noble metals such as (In); water-repellent substances such as polytetrafluoroethylene (PTFE); and conductive oxides. As for materials other than polycrystalline graphite, only 1 type may be used and 2 or more types may be used together.

  The thickness of the conductive carbon layer 33 (however, excluding the protruding particles 33a; the average value) is not particularly limited. However, Preferably it is 1-1000 nm, More preferably, it is 2-500 nm, More preferably, it is 5-200 nm. If the thickness of the conductive carbon layer 33 is a value within such a range, sufficient conductivity can be secured between the gas diffusion base material and the separator 5. Moreover, the advantageous effect that a high corrosion-resistant function can be given with respect to the metal base material 31 can be produced. In the present embodiment, the conductive carbon layer 33 may exist only on one main surface of the conductive member (separator 5), but preferably the conductive member (separator 5) as shown in FIGS. It is desirable that the conductive carbon layer 33 exists on the other main surface (that is, on both surfaces of the conductive member). This improves the anticorrosion effect of the base material while ensuring the adhesion between the metal base material 31 and the conductive carbon layer 33 via the intermediate layer 32 on both surfaces of the conductive member (conductive carbon layer 33). This is because it can be further maintained.

  Hereinafter, although more preferable embodiment in the electroconductive carbon layer 33 of this embodiment is described, the technical scope of this invention is not limited only to the following form.

  First, with respect to the Raman scattering spectroscopic analysis of the conductive carbon layer 33, it is preferable from another viewpoint that the average peak measured by the rotational anisotropy measurement of the Raman scattering spectroscopic analysis shows a two-fold symmetry pattern. Hereinafter, the measurement principle of rotational anisotropy measurement will be briefly described.

  The rotational anisotropy measurement of the Raman scattering spectroscopic analysis is performed by performing the Raman scattering spectroscopic measurement while rotating the measurement sample 360 degrees in the horizontal direction. Specifically, the surface of the measurement sample is irradiated with laser light, and a normal Raman spectrum is measured. Next, the measurement sample is rotated by 10 °, and the Raman spectrum is measured in the same manner. This operation is performed until the measurement sample rotates 360 °. And the average peak is obtained by calculating the average value of the peak intensities obtained in the measurement at each angle and displaying the 360 ° polar coordinate with one peak at the center. For example, when the graphite layer is present on the sample surface so that the graphene surface is parallel to the surface direction of the sample, a three-fold symmetry pattern as shown in FIG. 5A can be seen. On the other hand, when the graphite layer is present on the sample surface so that the graphene surface is perpendicular to the surface direction of the sample, a two-fold symmetry pattern as shown in FIG. 5B can be seen. When an amorphous carbon layer having no clear crystal structure is present on the sample surface, a pattern not showing symmetry as shown in FIG. 5C can be seen. Therefore, the fact that the average peak ga symmetric pattern measured by rotational anisotropy measurement shows a plane direction of the graphene surface constituting the conductive carbon layer 33 substantially coincides with the stacking direction of the conductive carbon layer 33. Means that According to such a form, the conductivity in the conductive carbon layer 33 is ensured by the shortest path, which is preferable.

  Here, the results of the rotational anisotropy measurement described above are shown in FIGS. 6A and 6B. FIG. 6A shows Raman spectra when the conductive member B is used as a measurement sample, and the rotation angles of the sample are 0 °, 60 °, and 180 °, respectively. FIG. 6B shows an average peak of rotational anisotropy measurement for the conductive member B obtained by the above-described method. As shown in FIG. 6B, in the rotational anisotropy measurement of the conductive member B, peaks were observed at 0 ° and 180 ° positions. This corresponds to the two-fold symmetry pattern shown in FIG. 5B. In the present specification, the average peak measured by rotational anisotropy measurement of Raman scattering spectroscopic analysis “shows a two-fold symmetric pattern” means that, as shown in FIG. 5B and FIG. This means that there are two peaks that are 180 ° opposite to each other with the intensity being zero. Since the peak intensity seen in the 3-fold symmetrical pattern and the peak intensity seen in the 2-fold symmetrical pattern are supposed to show the same value in principle, such a definition is possible.

  In a preferred embodiment, the Vickers hardness of the conductive carbon layer 33 is defined. “Vickers hardness (Hv)” is a value that defines the hardness of a substance, and is a value inherent to the substance. In this specification, the Vickers hardness means a value measured by a nanoindentation method. The nanoindentation method is a method in which the diamond indenter is continuously loaded and unloaded with a very small load on the sample surface, and the hardness is measured from the obtained load-displacement curve. Larger means that the substance is harder. In a preferred embodiment, specifically, the Vickers hardness of the conductive carbon layer 33 is preferably 1500 Hv or less, more preferably 1200 Hv or less, still more preferably 1000 Hv or less, and particularly preferably 800 Hv or less. . When the Vickers hardness is within such a range, excessive mixing of sp3 carbon having no conductivity can be suppressed, and a decrease in conductivity of the conductive carbon layer 33 can be prevented. On the other hand, the lower limit value of the Vickers hardness is not particularly limited, but if the Vickers hardness is 50 Hv or more, the hardness of the conductive carbon layer 33 is sufficiently ensured. As a result, it is possible to withstand impacts such as external contact and friction, and a conductive member having excellent adhesion to the base metal substrate 31 and the intermediate layer 32 according to the present invention ( Separator) may be provided. From such a viewpoint, the Vickers hardness of the conductive carbon layer 33 is more preferably 80 Hv or more, further preferably 100 Hv or more, and particularly preferably 200 Hv or more.

Here, SUS316L (when the intermediate layer 32 according to the present embodiment is used, an easily corroded metal such as aluminum or an alloy thereof can be suitably used) is prepared as the metal base 31 of the conductive member. An intermediate layer 32 made of Cr (thickness: 0.2 μm, having a columnar crystal structure) and a conductive carbon layer 33 (thickness: 0.2 μm, projecting particles 33a are present on the outermost surface. Are manufactured sequentially by a sputtering method. In the intermediate layer 32 here, the average value of the columnar crystal column thickness in the cross section of the intermediate layer is 200 to 500 nm, and the columnar crystal having the thickness is electrically conductive in the entire intermediate layer. A carbon layer having 60% of the total thickness of the intermediate layer was used. Further, in the conductive carbon layer 33 here, on the outermost surface, the protruding particles 33a having a diameter (particle size distribution) of 200 to 500 nm and the fine particles 33b of 50 to 100 nm are mixed, and the protruding shape is formed. A particle having 33 particles (average value) per 100 μm ² was used. At this time, by controlling the bias voltage and the film formation method, the crystal structure of the intermediate layer is controlled to create (grow) the columnar crystal diameter having the desired column diameter and number, and then the Vickers of the conductive carbon layer 33 is formed. The hardness was changed. FIG. 7 shows the relationship between the Vickers hardness of the conductive carbon layer 33 and the value of the sp3 ratio in the conductive carbon layer 33 in the conductive member thus obtained. In FIG. 7, diamond has an sp3 ratio = 100% and becomes Hv10000. From the results shown in FIG. 7, it can be seen that when the Vickers hardness of the conductive carbon layer 33 is 1500 Hv or less, the value of the sp3 ratio is greatly reduced. Moreover, it is estimated that the value of the contact resistance of a conductive member also falls along with this, when the value of sp3 ratio falls.

  From another point of view, it is preferable to consider the amount of hydrogen atoms contained in the conductive carbon layer 33 as well. That is, when the conductive carbon layer 33 includes a hydrogen atom, the hydrogen atom is bonded to the carbon atom. Then, the hybrid orbital of the carbon atom to which the hydrogen atom is bonded changes from sp2 to sp3 and loses conductivity, so that the conductivity of the conductive carbon layer 33 is lowered. Further, when the C—H bond in the polycrystalline graphite is increased, the continuity of the bond is lost, the hardness of the conductive carbon layer 33 is lowered, and finally the mechanical strength and the corrosion resistance of the conductive member are lowered. . From such a viewpoint, the content of hydrogen atoms in the conductive carbon layer 33 is preferably 30 atomic percent or less, more preferably 20 atomic percent or less, with respect to all atoms constituting the conductive carbon layer 33. More preferably, it is 10 atomic% or less. Here, as the value of the hydrogen atom content in the conductive carbon layer 33, a value obtained by elastic recoil scattering analysis (ERDA) is adopted. In this method, a measurement sample is tilted, and a helium ion beam is incident shallowly, thereby detecting an element ejected forward. Since the nucleus of a hydrogen atom is lighter than the incident helium ion, if a hydrogen atom is present, the nucleus is ejected forward. Since such scattering is elastic scattering, the energy spectrum of the ejected atom reflects the mass of the nucleus. Therefore, the content of hydrogen atoms in the measurement sample can be measured by measuring the number of nuclei of ejected hydrogen atoms with a solid detector.

Here, FIG. 8 is a graph showing the results of measuring the contact resistance of several conductive members having the conductive carbon layer 33 having the above-described R value of 1.3 or more but having different hydrogen atom contents. It is. As shown in FIG. 8, when the hydrogen atom content in the conductive carbon layer 33 is 30 atomic% or less, the value of the contact resistance of the conductive member is significantly reduced. In the experiment shown in FIG. 8, as the metal base 31 of the conductive member, SUS316L (when using the intermediate layer 32 according to the present embodiment, a corrosive metal such as aluminum or an alloy thereof can be suitably used. ) Was used. An intermediate layer 32 made of Cr (thickness: 0.2 μm, having a columnar crystal structure) and a conductive carbon layer 33 (thickness: 0.2 μm, projecting on the outermost surface) The particles 33a in which particles 33a are present) were sequentially formed by a sputtering method. In the intermediate layer 32 here, the average value of the columnar crystal column thickness in the cross section of the intermediate layer is 200 to 500 nm, and the columnar crystal having the thickness is electrically conductive in the entire intermediate layer. A carbon layer having 60% of the total thickness of the intermediate layer was used. Further, in the conductive carbon layer 33 here, on the outermost surface, the protruding particles 33a having a diameter (particle size distribution) of 200 to 500 nm and the fine particles 33b of 50 to 100 nm are mixed, and the protruding shape is formed. A particle having 33 particles (average value) per 100 μm ² was used. At this time, by controlling the film formation method and the amount of hydrocarbon gas, the crystal structure of the intermediate layer is controlled to create (grow) the columnar crystal diameter having the desired column diameter and number, and then the conductive carbon layer 33. The content of hydrogen atoms in was changed.

  In the present embodiment, the entire metal base 31 is covered with the conductive carbon layer 33 via the intermediate layer 32. In other words, in this embodiment, the ratio (coverage) of the area where the metal base 31 is covered with the conductive carbon layer 33 is 100%. However, it is not limited only to such a form, and the coverage may be less than 100%. The coverage of the metal substrate 31 by the conductive carbon layer 33 is preferably 50% or more, more preferably 80% or more, still more preferably 90% or more, and most preferably 100%. By setting it as such a structure, the fall of electroconductivity and corrosion resistance accompanying the formation of the oxide film in the exposed part of the metal base material 31 which is not coat | covered with the electroconductive carbon layer 33 can be suppressed effectively. In addition, when the intermediate layer 32 is interposed between the metal base 31 and the conductive carbon layer 33 as in the present embodiment, the coverage is obtained when the conductive member (metal separator 5) is viewed from the stacking direction. The ratio of the area of the metal substrate 31 overlapping with the conductive carbon layer 33 is meant.

[Middle layer]
As shown in FIG. 3, in the present embodiment, the conductive member constituting the separator 5 has an intermediate layer 32. The intermediate layer 32 has a function of improving the adhesion between the metal substrate 31 and the conductive carbon layer 33 and a function of preventing elution of ions from the metal substrate 31. In particular, when the R value exceeds the upper limit of the preferable range described above, the effect of providing the intermediate layer 32 is remarkably exhibited. However, it is a matter of course that the intermediate layer 32 can be provided even when the R value is included in the preferred range described above. From another point of view, the above-described operation and effect due to the installation of the intermediate layer 32 is more prominent when the metal base 31 is made of aluminum or an alloy thereof. In the present invention, the intermediate layer 32 is a main layer, and the intermediate layer 32 always exists. Hereinafter, a preferable mode when the intermediate layer 32 is provided on the conductive member will be described.

  The material constituting the intermediate layer 32 is not particularly limited as long as it provides the above adhesion. For example, Group 4 metals (Ti, Zr, Nf) of the periodic table, Group 5 metals (V, Nb, Ta), Group 6 metals (Cr, Mo, W), and their carbides, Examples thereof include nitrides and carbonitrides. Among these, metals with low ion elution such as chromium (Cr), tungsten (W), titanium (Ti), molybdenum (Mo), niobium (Nb) or hafnium (Hf), or their nitrides, carbides or charcoal are preferable. Nitride is used. More preferably, Cr or Ti, or a carbide or nitride thereof is used. In particular, when Cr or Ti, or their carbides or nitrides are used, the role of the intermediate layer 32 is to ensure adhesion with the upper conductive carbon layer (film) 33 and to prevent corrosion of the underlying metal substrate 31. There is. In particular, in the case of the metal substrate 31 made of aluminum or an alloy thereof, corrosion proceeds due to moisture reaching the vicinity of the interface, and an aluminum oxide film is formed. As a result, the conductivity in the film thickness direction of the entire metal base 31 is deteriorated. Chromium and titanium (Cr or Ti, or their carbides or nitrides) are particularly useful in that, due to the formation of a passive film, even if exposed parts are present, there is almost no elution of itself. . Especially, when the metal (especially Cr or Ti) with little ion elution mentioned above or its carbide | carbonized_material or nitride is used, it is excellent also in the point which can improve the corrosion resistance of the metal separator 5 significantly. Thereby, the corrosion resistance of the metal separator 5 can be maintained.

  In the intermediate layer 32, the average value of the columnar crystal column thickness in the cross section of the intermediate layer 32 is 200 to 500 nm, preferably 300 to 500 nm, more preferably 300 to 400 nm. Since the average value of the columnar crystal column thickness in the cross section of the intermediate layer 32 has columnar crystals with such a range of thickness, the amount of gaps between the columnar crystals decreases, and the intrusion of moisture reaching the metal substrate (Refer to FIG. 3B and FIG. 3C for comparison.) This is because by changing the negative bias voltage from at least a low value to a high value at the time of forming the intermediate layer 32 by the dry film forming method, the column diameter of the columnar crystals becomes small and high when the bias voltage is low. When the value is set, the column diameter increases. In the initial stage of intermediate layer deposition in the dry deposition method, deposition is started at a low bias voltage so as not to deteriorate the roughness of the interface with the metal substrate 31, and then the bias voltage is shifted to a high value to form a columnar shape. Grow crystals thicker. The conductive carbon layer 33 grows with the columnar crystal column diameter of the intermediate layer 32. By increasing the column diameter of the columnar crystals of the intermediate layer 32, gaps in the intermediate layer 32 and defects of the conductive carbon layer 33 existing thereon are reduced, and water is prevented from entering to oxidize at each interface. It is possible to suppress the increase in contact resistance. Moreover, as a manufacturing method, it is a simple method which only changes the set value of the apparatus. Alternatively, after the surface of the metal substrate 31 is polished, a coating process is performed on the surface of the substrate 31 to form a film by sputtering. The number of nucleation sites is reduced, and the column diameter of each columnar crystal can be increased. As a result, the same effect as the effect of changing the negative bias voltage from at least a low value to a high value at the time of forming the intermediate layer 32 can be obtained, the columnar crystals of the intermediate layer 32 can be grown thick, and the conductivity The carbon layer 33 can also be grown with the columnar crystal column diameter of the intermediate layer 32. Therefore, also in the manufacturing method, by increasing the column diameter of the columnar crystal of the intermediate layer 32, the gaps in the intermediate layer 32 and the defects of the conductive carbon layer 33 existing thereon are reduced, and the entry of water is prevented. Thus, oxidation at each interface can be suppressed and increase in contact resistance can be suppressed. As described above, when the intermediate layer 32 is provided between the conductive carbon layer 33 and the metal substrate 31, the crystal structure of the intermediate layer 32 is controlled, and the column diameter (columnar diameter) of the columnar crystal of the intermediate layer 32 is made conductive. The interface is made thicker (larger) to the interface with the carbonaceous layer 33. As a result, gaps and defects in the conductive carbon layer 33 formed thereon can be significantly reduced. When projecting particles 33a having a diameter of 200 to 500 nm are present in the outermost surface layer of the conductive member, this is caused by the development of the column diameter of the intermediate layer 32 (the column diameter of the columnar crystal having a size in the above-mentioned range) Thus, the number of gaps in the outermost layer of the conductive member is reduced, and a function of suppressing water intrusion can be provided. Thereby, the anticorrosion effect of the metal base material 32 can be enhanced, and even in the case of the metal base material 31 that is easily corroded such as aluminum, it can be applied as the base material 31 of the separator 5.

  In the intermediate layer 32, the columnar crystal in the cross section has a columnar crystal thickness of 200 to 500 nm. Of the entire intermediate layer 32, the columnar crystal has the entire thickness of the intermediate layer 32 on the conductive carbon layer 33 side. It is desirable that it is present in an amount of 5 to 95%. It is desirable that the thickness of the columnar crystal on the outermost surface of the intermediate layer 32 is maintained up to the interface between the metal base 31 and the intermediate layer 32 as much as possible. However, when the intermediate layer 32 is first formed on the metal base 31, the energy applied to the surface is increased in order to thicken the column (columnar crystal) from the beginning, which may cause poor adhesion. Therefore, it is preferable that the thickness of the column diameter (of the columnar crystals) on the metal substrate 31 side of the intermediate layer 32 is thinner than that of the conductive carbon layer 33 side (column diameter of the columnar crystals). Thereby, the anticorrosion effect of the base material 31 can be maintained more stably while ensuring the adhesion between the metal base material 31 and the conductive carbon layer 33. Here, in the intermediate layer 32, the thickness of the columnar column in the cross section is 200 to 500 nm, preferably 300 to 500 nm, and more preferably 300 to 400 nm. Further, the columnar crystal having the above thickness is 5 to 95%, preferably 20 to 90%, more preferably 50 to 90% of the entire thickness of the intermediate layer 32 on the conductive carbon layer 33 side in the entire intermediate layer 32. It is desirable to exist.

  The film thickness of the intermediate layer 32 is not particularly limited. However, from the viewpoint of making the size of the fuel cell stack as small as possible by making the separator 5 thinner, the thickness of the intermediate layer 32 is preferably 0.01 to 10 μm, more preferably 0. 0.05 to 5 μm, more preferably 0.02 to 5 μm, and particularly 0.1 to 1 μm. If the thickness of the intermediate layer 32 is 0.01 μm or more, a uniform layer is formed, and the corrosion resistance of the metal substrate 31 can be effectively improved. On the other hand, if the thickness of the intermediate layer 32 is 10 μm or less, an increase in the film stress of the intermediate layer 32 can be suppressed, and a decrease in film followability to the metal substrate 31 and occurrence of peeling / cracking associated therewith can be prevented. .

  In particular, the thickness of the intermediate layer 32 is preferably 0.02 to 5 μm. When the intermediate layer 32 has a film thickness within the above range, it is more desirable to have the following configuration. The column of the columnar crystal structure having a thickness of 200 to 500 nm on the outermost surface (outermost layer) of the intermediate layer 32 on the conductive carbon layer 33 side is the outermost surface (on the conductive carbon layer 33 side). It is desirable that the thickness of the intermediate layer 32 is maintained within a range of 5% or more with respect to the direction of the metal base 31 from the outermost layer. Here, the column of the columnar crystal structure on the outermost surface (outermost layer) of the intermediate layer 32 on the conductive carbon layer 33 side has a thickness of 200 to 500 nm, preferably 300 to 500 nm, more preferably 300 to 400 nm. A column having a columnar crystal structure is desirable. Moreover, 5% or more of the whole intermediate layer 32 film thickness with respect to the metal base material 31 direction from the outermost surface (outermost layer) of the intermediate layer 32 on the conductive carbon layer 33 side, preferably 20 to 90%, more preferably. It is desirable to maintain in the range of 50 to 90%.

  This is because when the film thickness of the intermediate layer 32 is less than 0.02 μm (20 nm), the columnar crystal structure of the intermediate layer 32 is undeveloped, and it is difficult to maintain denseness. On the other hand, when the film thickness of the intermediate layer 32 exceeds 5 μm, the film stress increases and the adhesiveness with the metal substrate 31 is deteriorated, so that cracks and peeling may occur. However, as described above, the thickness of the intermediate layer 32 may be increased to about 10 μm as long as the intended effect of the present invention is not impaired. Furthermore, it is desirable that the column thickness of the columnar crystal structure on the outermost surface of the intermediate layer 32 is maintained up to the interface between the metal base 31 and the intermediate layer 32 as much as possible. However, when the intermediate layer 32 is first formed on the metal base 31, in order to thicken the columnar crystal structure from the beginning, the energy applied to the surface becomes high, which may cause poor adhesion. Therefore, it is preferable that the thickness of the column diameter of the columnar crystal structure of the metal base 31 is thinner than the column diameter of the columnar crystal structure on the conductive carbon layer 33 side in the thickness of the intermediate layer 32. By having such a configuration (three-dimensional structure) of the intermediate layer 32, the anticorrosion effect of the metal substrate 31 is further stabilized while firmly securing the mutual adhesion between the metal substrate 31 and the conductive carbon layer 33. Can be maintained.

  In addition, the surface of the intermediate layer 32 on the conductive carbon layer 33 side is preferably rough at the nano level. According to such a configuration, the adhesion of the conductive carbon layer 33 formed on the intermediate layer 32 to the intermediate layer 32 can be further improved. The structure that also satisfies such a requirement is a conductive member in which the metal substrate of the present invention, an intermediate layer is provided on the metal substrate, and a conductive carbon layer is coated on the intermediate layer, It can be said that the intermediate layer has a columnar crystal structure, and the protruding particles 33a exist on the outermost surface of the conductive member. More preferably, it can be said that the metal substrate 31, the intermediate layer 32, and the conductive carbon layer 33 have the above-described configurations (structures).

Furthermore, when the thermal expansion coefficient of the intermediate layer 32 is a value close to the thermal expansion coefficient of the metal constituting the metal substrate 31, the adhesion between the intermediate layer 32 and the metal substrate 31 is improved. However, in such a form, the adhesion between the intermediate layer 32 and the conductive carbon layer 33 may be reduced. Similarly, when the thermal expansion coefficient of the intermediate layer 32 is close to the thermal expansion coefficient of the conductive carbon layer 33, the adhesion between the intermediate layer 32 and the metal substrate 31 may be lowered. Taking these into consideration, the thermal expansion coefficient (α _mid ) of the intermediate layer 32, the thermal expansion coefficient (α _sub ) of the metal substrate 31, and the thermal expansion coefficient (α _c ) of the conductive carbon layer 33 are expressed by α _sub It is preferable that the relationship of> α _mid > α _c is satisfied.

  The intermediate layer 32 is preferably present on both surfaces of the metal base 31, but in the case of use in an application location that does not impair the intended effect of the present invention, on either surface. May exist only. However, when the conductive carbon layer 33 exists only on one main surface of the metal substrate 31, the intermediate layer 32 exists between the metal substrate 31 and the conductive carbon layer 33. In addition, the conductive carbon layer 33 may exist on both surfaces of the metal base 31 as described above. In such a case, the intermediate layer 32 is preferably interposed between the metal base 31 and both the conductive carbon layers 33, respectively. When the intermediate layer 32 exists only between the metal substrate 31 and one of the conductive carbon layers 33, the intermediate layer 32 is disposed on the MEA 9 side in the PEFC 1. It is preferable that it exists between 33 and the metal base material 31 (refer FIG.1, 2, 11, 12, etc.).

  FIG. 21 shows a manufacturing apparatus for forming (forming) at least one of the conductive members of the present invention, in particular, the intermediate layer 32 and the conductive carbon layer 33, and preferably forming each of these layers in sequence using a sputtering method. FIG. Here, as a sputtering apparatus, an apparatus applicable to the unbalanced magnetron sputtering (UBMS) method used in the examples is shown.

  22 shows at least one of the conductive members of the present invention, in particular, the intermediate layer 32 and the conductive carbon layer 33, preferably each of these layers is formed (formed) using the arc ion plating (AIP) method in order. It is the plane schematic diagram of the manufacturing apparatus for carrying out. However, FIG. 21 and FIG. 22 show an example in which an existing disk-shaped wafer is set in place of the flat metal separator 5 before the uneven pressing.

  When sputtering is performed using the apparatuses 300 and 400 shown in FIGS. 21 and 22, one or a plurality of metal separators 5 are arranged on the rotating tables 301 and 401, respectively, so as to form films on the front and back of each metal separator 5. Each metal separator 5 itself also rotates in a direction perpendicular to the rotating surface (rotating shaft) of the rotating table. The arrow method of each of the metal separators 5 of the rotating tables 301 and 401 indicates the direction of rotation in which the rotation surfaces (axes) are orthogonal to each other.

The vacuum chambers 303 and 403 shown in FIGS. 21 and 22 are held at a level of 10 ⁻¹ to 10 ⁻² Torr, and as necessary. Gases (not shown) such as N ₂ and Ar can be introduced from the air supply ports 305 and 405. Unnecessary atmospheric gas and excess gas source are appropriately exhausted from the exhaust ports 307 and 407 in order to control a predetermined pressure (vacuum pressure or the like) in the vacuum chambers 303 and 403.

  Temperature control equipment is connected to the vacuum chambers 303 and 403 and the tables 301 and 401 themselves holding the metal separators 5 so that the temperature can be adjusted.

  First, the oxide film present on the surface of the metal separator 5 is removed from the surface of each metal separator 5 shown in FIGS. 21 and 22 by Ar ion bombardment (reverse sputtering). Since the oxide film is formed with a thickness of several angstroms, the removal time may be several seconds to several minutes. In the present embodiment, Cr is disposed as the intermediate layer 32 before the conductive carbon layer 33 is formed. Therefore, Cr targets (sputtering targets (Cr)) 309 and 409 are disposed in the chambers 301 and 401, respectively. After the formation of the intermediate layer 32 of Cr, the conductive carbon layer 33 is formed by using the carbon (target) (sputtering target (C)) 311 and 411 disposed in the same chambers 301 and 401. As shown in FIG. 20, the intermediate layer 32 may be formed in various patterns in which the negative bias voltage at the time of forming the intermediate layer is changed from at least a low value to a high value. In this case, the negative bias voltage value may be changed twice or more (may be changed continuously) to form a film. In addition, it can be formed continuously by changing the bias voltage, temperature, degree of vacuum, etc. of each metal separator 5. The formation of the conductive carbon layer 33 may be performed without changing the bias voltage or the like at a predetermined value (see each example), or may be changed twice or more (while continuously changing). It is also possible to perform film formation. In addition, it can be formed continuously by changing the bias voltage, temperature, degree of vacuum, etc. of each metal separator 5. The conductive carbon layer 33 is preferably sputtered using a solid (for example, carbon graphite) as a target because hydrogen tends to be present due to the presence of hydrogen in the carbon molecules forming the layer.

  When the conductive carbon layer 33 is formed by arc ion plating (AIP) using the apparatus shown in FIG. 22, the target (sputtering target (C)) 411 is used as the target as in FIG. However, by disposing another vapor deposition source 413 for arc discharge, it is possible to form a film in the same chamber 401 without reducing the degree of vacuum. Also in the formation of the conductive carbon layer 33 by the AIP method using the apparatus shown in FIG. 22, in order to obtain the conductive carbon layer 33 having a predetermined characteristic, the conditions (voltage / current), the degree of vacuum, The temperature, bias voltage, etc. may be constant without changing them at predetermined values, or can be formed by changing them as appropriate.

  The conductive carbon layer 33 can be formed by, for example, using the apparatus shown in FIGS. 21 and 22, after the deposition of the intermediate layer 32, after changing the target, the bias (voltage), the temperature, the degree of vacuum, the supply gas amount (minute). It is desirable to form the same batch or process using the same apparatus and method by changing at least one of the pressure. This is because the conductive carbon layer 33 can be continuously formed after the formation of the intermediate layer 32 and can be formed on the same film formation process, which is excellent in terms of low cost.

  In the present invention, the intermediate layer 32 and the conductive carbon layer 33 are formed by sputtering using the apparatus shown in FIG. 21, or by the AIP method or ECR sputtering method using the apparatus shown in FIG. desirable. This is because a conductive path from one surface of the conductive carbon layer 33 to the other surface is secured by using a sputtering method or an AIP method, which is a dry film formation method, for the intermediate layer 32 and the conductive carbon layer 33. Thus, it is excellent in that a conductive member having further improved corrosion resistance can be provided while sufficiently ensuring excellent conductivity. Further, in the conductive member having the intermediate layer 32 between the metal base layer 31 and the conductive carbon layer 33, a means for suppressing an increase in contact resistance while sufficiently ensuring the excellent conductivity can be provided. Excellent in terms.

  In forming the intermediate layer 32 and the conductive carbon layer 33, a solid source (eg, graphite carbon) is desirable. With a gas source, it is difficult to produce a good gas type that is currently used. This is because hydrogen enters the film (resulting in a decrease in conductivity).

  Note that the size and number of the targets 309, 311, 409, 411, and 413 can be adjusted as appropriate depending on the size and the processing amount of the metal separator 5.

  In the present invention, not only the metal separator 5 but also the surface of a component that requires conductivity and corrosion resistance can be applied anywhere. For example, current collecting plates 30 and 40 (see FIG. 11) disposed at both ends of the stack 20 in which a plurality of cells are stacked, a gas diffusion layer (GDL) 4, and terminal connection portions for monitoring voltage (not shown). And the like (see the output terminals 37 and 47 in FIG. 12).

  In the present embodiment, when the intermediate layer is formed on the metal substrate in the dry film forming method, the dry film forming method is preferably a sputtering method or an ion plating method. However, the present invention is not limited to these, and various conventionally known film forming techniques described above can be used.

  Hereinafter, the components of the PEFC using the separator formed of the conductive member of the present embodiment will be described with reference to FIGS. However, the present invention is characterized by the conductive member constituting the separator. Therefore, specific forms such as the shape of the separator in the PEFC and specific forms of members other than the separator constituting the fuel cell can be appropriately modified with reference to conventionally known knowledge. 11 is a schematic cross-sectional view for explaining an example of a fuel cell stack configuration in which a plurality of unit cell configurations of the fuel cell in FIG. 1 are stacked, and FIG. 12 is a perspective view of the fuel cell stack configuration in FIG. It is.

[Electrolyte layer]
The electrolyte layer is composed of the solid polymer electrolyte membrane 2 as shown in FIGS. This solid polymer electrolyte membrane 2 has a function of selectively permeating protons generated in the anode catalyst layer 3a during operation of the PEFC composed of a plurality of cell units 1 and the like to the cathode catalyst layer 3b along the film thickness direction. Have The solid polymer electrolyte membrane 2 also has a function as a partition wall for preventing the fuel gas 5ag supplied to the anode side and the oxidant gas 5bg supplied to the cathode side from being mixed.

  The solid polymer electrolyte membrane 2 is roughly classified into a fluorine-based polymer electrolyte membrane and a hydrocarbon-based polymer electrolyte membrane depending on the type of ion exchange resin that is a constituent material. Examples of ion exchange resins constituting the fluorine-based polymer electrolyte membrane include Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Co., Ltd.), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.), and the like. Perfluorocarbon sulfonic acid polymer, perfluorocarbon phosphonic acid polymer, trifluorostyrene sulfonic acid polymer, ethylene tetrafluoroethylene-g-styrene sulfonic acid polymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride- Examples include perfluorocarbon sulfonic acid polymers. From the viewpoint of improving power generation performance such as heat resistance and chemical stability, these fluorine-based polymer electrolyte membranes are preferably used, and particularly preferably fluorine-based polymer electrolytes composed of perfluorocarbon sulfonic acid polymers. A membrane is used.

  Specific examples of the hydrocarbon electrolyte include sulfonated polyethersulfone (S-PES), sulfonated polyaryletherketone, sulfonated polybenzimidazole alkyl, phosphonated polybenzimidazole alkyl, sulfonated polystyrene, and sulfonated poly. Examples include ether ether ketone (S-PEEK) and sulfonated polyphenylene (S-PPP). These hydrocarbon polymer electrolyte membranes are preferably used from the viewpoint of production such that the raw material is inexpensive, the production process is simple, and the material selectivity is high. In addition, as for the ion exchange resin mentioned above, only 1 type may be used independently and 2 or more types may be used together. Moreover, it is not restricted only to the material mentioned above, Other materials may be used.

  The thickness of the electrolyte layer may be appropriately determined in consideration of the characteristics of the obtained fuel cell, and is not particularly limited. The thickness of the electrolyte layer is usually about 5 to 300 μm. When the thickness of the electrolyte layer is within such a range, the balance of strength during film formation, durability during use, and output characteristics during use can be appropriately controlled.

[Catalyst layer]
The catalyst layers 3 (the anode catalyst layer 3a and the cathode catalyst layer 3b) shown in FIGS. 1 and 11 are layers in which the cell reaction actually proceeds. Specifically, the oxidation reaction of hydrogen proceeds in the anode catalyst layer 3a, and the reduction reaction of oxygen proceeds in the cathode catalyst layer 3b.

  The catalyst layer 3 includes a catalyst component, a conductive catalyst carrier that supports the catalyst component, and an electrolyte. Hereinafter, a composite in which a catalyst component is supported on a catalyst carrier is also referred to as an “electrode catalyst”.

  The catalyst component used in the anode catalyst layer 3a is not particularly limited as long as it has a catalytic action in the hydrogen oxidation reaction, and a known catalyst can be used in the same manner. The catalyst component used for the cathode catalyst layer 3b is not particularly limited as long as it has a catalytic action for the oxygen reduction reaction, and a known catalyst can be used in the same manner. Specifically, it may be selected from metals such as platinum, ruthenium, iridium, rhodium, palladium, osmium, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum, and alloys thereof. .

  Among these, those containing at least platinum are preferably used in order to improve catalyst activity, poisoning resistance to carbon monoxide and the like, heat resistance, and the like. Although the composition of the alloy depends on the type of metal to be alloyed, the content of platinum is preferably 30 to 90 atomic%, and the content of the metal to be alloyed with platinum is preferably 10 to 70 atomic%. In general, an alloy is a generic term for a metal element having one or more metal elements or non-metal elements added and having metallic properties. The alloy structure consists of a eutectic alloy, which is a mixture of the component elements as separate crystals, a component element completely melted into a solid solution, and a component element composed of an intermetallic compound or a compound of a metal and a nonmetal. There is what is formed, and any may be used in the present application. At this time, the catalyst component used for the anode catalyst layer 3a and the catalyst component used for the cathode catalyst layer 3b can be appropriately selected from the above. In the present specification, unless otherwise specified, descriptions of the catalyst components for the anode catalyst layer and the cathode catalyst layer have the same definition for both. Therefore, they are collectively referred to as “catalyst components”. However, the catalyst components of the anode catalyst layer 3a and the cathode catalyst layer 3b do not have to be the same, and can be appropriately selected so as to exhibit the desired action as described above.

  The shape and size of the catalyst component are not particularly limited, and the same shape and size as known catalyst components can be adopted. However, the shape of the catalyst component is preferably granular. At this time, the average particle diameter of the catalyst particles is preferably 1 to 30 nm. When the average particle diameter of the catalyst particles is within such a range, the balance between the catalyst utilization rate related to the effective electrode area where the electrochemical reaction proceeds and the ease of loading can be appropriately controlled. The “average particle diameter of catalyst particles” in the present invention is the average of the crystallite diameter determined from the half-value width of the diffraction peak of the catalyst component in X-ray diffraction or the average particle diameter of the catalyst component determined from a transmission electron microscope image. It can be measured as a value.

  The catalyst carrier functions as a carrier for supporting the above-described catalyst component and an electron conduction path involved in the transfer of electrons between the catalyst component and another member.

  Any catalyst carrier may be used as long as it has a specific surface area for supporting the catalyst component in a desired dispersion state and sufficient electron conductivity, and the main component is preferably carbon. Specific examples include carbon particles made of carbon black, activated carbon, coke, natural graphite, artificial graphite and the like. “The main component is carbon” means that the main component contains carbon atoms, and is a concept that includes both carbon atoms and substantially carbon atoms. In some cases, elements other than carbon atoms may be included in order to improve the characteristics of the fuel cell. Note that “substantially consisting of carbon atoms” means that contamination of about 2 to 3 mass% or less of impurities can be allowed.

The BET specific surface area of the catalyst carrier may be a specific surface area sufficient to carry the catalyst component in a highly dispersed state, but is preferably 20 to 1600 m ² / g, more preferably 80 to 1200 m ² / g. When the specific surface area of the catalyst carrier is in such a range, the balance between the dispersibility of the catalyst component on the catalyst carrier and the effective utilization rate of the catalyst component can be appropriately controlled.

  The size of the catalyst carrier is not particularly limited, but from the viewpoint of controlling the ease of loading, the catalyst utilization, and the thickness of the catalyst layer within an appropriate range, the average particle size is about 5 to 200 nm, preferably 10 to 10 nm. About 100 nm is preferable.

  In the electrode catalyst in which the catalyst component is supported on the catalyst carrier, the supported amount of the catalyst component is preferably 10 to 80% by mass, more preferably 30 to 70% by mass with respect to the total amount of the electrode catalyst. When the supported amount of the catalyst component is within such a range, the balance between the degree of dispersion of the catalyst component on the catalyst support and the catalyst performance can be appropriately controlled. The amount of the catalyst component supported on the electrode catalyst can be measured by inductively coupled plasma emission spectroscopy (ICP).

  The catalyst layer 3 contains an ion conductive polymer electrolyte in addition to the electrode catalyst. The polymer electrolyte is not particularly limited, and conventionally known knowledge can be referred to as appropriate. For example, the ion exchange resin which comprises the electrolyte layer 2 mentioned above can be added to the catalyst layer 3 as a polymer electrolyte.

[Gas diffusion layer (GDL)]
The gas diffusion layer 4 (gas diffusion layer 4a, cathode gas diffusion layer 4b) shown in FIGS. 1 and 11 is a gas channel (fuel gas channel 5aa, oxidant gas) of the metal separator 5 (anode separator 5a, cathode separator 5b). The function of promoting the diffusion of the gas (fuel gas or oxidant gas) supplied through the flow path 5bb) to the catalyst layer 3 (the anode catalyst layer 3a and the cathode catalyst layer 3b) and the function as an electron conduction path Have.

  The material which comprises the base material of the gas diffusion layer 4 (4a, 4b) is not specifically limited, A conventionally well-known knowledge can be referred suitably. For example, a sheet-like material having conductivity and porosity such as a carbon woven fabric, a paper-like paper body, a felt, and a non-woven fabric can be used. The thickness of the base material of the gas diffusion layer 4 may be appropriately determined in consideration of the characteristics of the obtained gas diffusion layer, but may be about 30 to 500 μm. If the thickness of the base material of the gas diffusion layer 4 is within such a range, the balance between the mechanical strength and the diffusibility of gas, water, etc. can be controlled appropriately.

  The gas diffusion layer 4 preferably contains a water repellent for the purpose of further improving water repellency and preventing a flooding phenomenon or the like. Although it does not specifically limit as a water repellent, Fluorine-type high things, such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), polyhexafluoropropylene, and tetrafluoroethylene-hexafluoropropylene copolymer (FEP), are included. Examples thereof include molecular materials, polypropylene, and polyethylene.

  In order to further improve the water repellency, the gas diffusion layer 4 includes a carbon particle layer (microporous layer; MLP, not shown) made of an aggregate of carbon particles containing a water repellent agent on the catalyst layer side of the substrate. You may have.

  The carbon particles contained in the carbon particle layer are not particularly limited, and conventionally known materials such as carbon black, graphite, and expanded graphite can be appropriately employed. Among them, carbon black such as oil furnace black, channel black, lamp black, thermal black, acetylene black and the like can be preferably used because of excellent electron conductivity and a large specific surface area. The average particle diameter of the carbon particles is preferably about 10 to 100 nm. Thereby, while being able to obtain the high drainage property by capillary force, the contact property with the catalyst layer 4 can also be improved.

  Examples of the water repellent used in the carbon particle layer include the same water repellent as described above. Among these, fluorine-based polymer materials can be preferably used because of excellent water repellency, corrosion resistance during electrode reaction, and the like.

  The mixing ratio of the carbon particles to the water repellent in the carbon particle layer is about 90:10 to 40:60 (carbon particles: water repellent) in terms of mass ratio in consideration of the balance between water repellency and electron conductivity. It is good. The thickness of the carbon particle layer is not particularly limited and may be appropriately determined in consideration of the water repellency of the obtained gas diffusion layer, but is preferably 10 to 1000 μm, more preferably 50 to 500 μm. Good.

[Separator]
The metal separator 5 shown in FIGS. 1 and 11 is as described in the examples described later.

The conductive member of this embodiment can be used for various applications. A typical example is the PEFC separator 5 shown in FIG. However, the use of the conductive member of the present embodiment is not limited to this. For example, in addition to PEFC, various fuel cell separators such as phosphoric acid fuel cell (PAFC), molten carbonate fuel cell (MCFC), solid electrolyte fuel cell (SOFC) or alkaline fuel cell (AFC) Can also be used. In addition to the fuel cell separator, the separator can be used in various applications that require both conductivity and corrosion resistance. Examples of uses other than the fuel cell separator in which the conductive member of the present embodiment can be used include other fuel cell components (current collector plate, bus bar, gas diffusion base material, MEA), contacts of electronic components, and the like. . In another preferred embodiment, the conductive member of the present embodiment is used in a wet environment and an energized environment. When used in such an environment, the effect of the present invention of achieving both conductivity and corrosion resistance can be remarkably exhibited.
[Basic configuration of cell unit]
1 and 11, the basic structure of a single cell (cell unit) 1 of a solid polymer fuel cell is that a fuel electrode side electrode catalyst layer 3 a and a fuel electrode side gas diffusion are formed on both sides of a solid polymer electrolyte membrane 2. The fuel electrode composed of the layer 4a and the oxygen electrode composed of the oxygen electrode side electrode catalyst layer 3b and the oxygen electrode side gas diffusion layer 4b each have an MEA 9 disposed opposite to each other. It is sandwiched between the electrode separator 5a and the oxygen electrode separator 5b. Further, the fuel gas 5ag (hydrogen-containing gas) and the oxidant gas 5bg (air) supplied to the MEA are supplied to the fuel electrode side separator 5a and the oxygen electrode side separator 5b, to the fuel electrode side electrode catalyst layer 3a and the oxygen electrode side electrode. The gas is supplied through a fuel gas flow path 5aa and an oxidant gas flow path 5bb formed at a plurality of locations on the surface facing the catalyst layer 3b.

  In order to use the cell unit (single cell) 1 for the fuel cell (stack) 20, a single cell 1 or a stack in which two or more single cells 1 are stacked (stacked stack) is further used in the thickness direction of the single cells 1 to the stacked stack. Are used by fastening with a pair of end plates, ie, a fuel electrode side end plate 70 and an oxygen electrode side end plate 80 from both sides (both ends) (see FIG. 12).

  More specifically, as a configuration of the fuel cell stack 20 (a portion sandwiched between the current collector plates 30 and 40), as shown in FIG. 11, a plurality of single cells (cell units) 1 of fuel cells are stacked. It has a stack unit 20 and is used as a power source. Applications of the power source include, for example, stationary devices, consumer portable devices such as mobile phones, emergency devices, outdoor devices such as leisure and construction power sources, and mobile objects such as automobiles with limited mounting space. In particular, the mobile power supply is preferably applied because a high output voltage is required after a relatively long period of shutdown. Further, in a vehicle equipped with the fuel cell of the present invention, the thickness can be reduced and the cost can be reduced through components (conductive members) such as the metal separator 5 and current collector plates 30 and 40 of the fuel cell (PEFC). This can contribute to an improvement in the output density of the fuel cell. Therefore, the vehicle weight can be reduced and the vehicle cost can be reduced, and when a fuel cell having the same volume is mounted, the vehicle can run for a longer distance and the acceleration performance can be improved.

  In the single cell (cell unit) 1 of the fuel cell according to the present invention, the thickness can be reduced and the cost can be reduced through components (conductive members) such as the metal separator 5 and current collector plates 30 and 40 of the fuel cell (PEFC). When 20 is formed, it can contribute to the improvement of the output density of the fuel cell stack 20. In addition, the corrosion resistance of the components (conductive members) such as the metal separator 5 and the current collector plates 30 and 40 of the fuel cell is excellent, and the durability (long life) of the fuel cell stack 20 can also be achieved.

  On both sides of the stack part 20, current collecting plates 30, 40, insulating plates 50, 60 and end plates 70, 80 are arranged. The current collecting plates 30 and 40 are made of a gas impermeable conductive member such as dense carbon, copper plate, or aluminum plate, and are provided with output terminals 37 and 47 for outputting the electromotive force generated in the stack portion 20. It has been. The insulating plates 50 and 60 are formed from an insulating member such as rubber or resin.

  Here, instead of the above-described carbon or the like, the current collector plates 30 and 40 are made of a copper plate, an aluminum plate, or the like having poor corrosion resistance while being thinner and lighter than stainless steel from the viewpoint of thinning and cost reduction. When used for the electric plates 30 and 40, the configuration of the present invention can be adopted. With this configuration, it is possible to form a conductive member in which resistance is reduced on the outermost surface of the conductive carbon layer 33 while preventing the base material 31 from being corroded by the ingress of droplets in the intermediate layer 32. As a result, the chemical stability can be maintained even if the metal current collector plates 30 and 40 are exposed to an acidic atmosphere while maintaining the conductivity. Specifically, the surface treatment can effectively suppress the ion elution property against defects such as pinholes without increasing the electrical resistance (here, contact resistance with the separator 5 as shown in FIG. 11). The applied current collecting plates 30 and 40 can be provided.

  As shown in FIGS. 1, 2, and 12, the end plates 70 and 80 are made of a material having rigidity, for example, a metal material such as steel. The end plates 70 and 80 are provided with a fuel gas flow path (hydrogen-containing gas flow path) 5aa and an oxidant in order to circulate the fuel gas 5ag (for example, hydrogen), the oxidant gas 5bg (for example, oxygen), and the cooling water 8w. A fuel gas inlet 71, a fuel gas outlet 72, an oxidant gas inlet 74, and an oxidant gas outlet that communicate with the gas passage (oxygen gas passage) 5 bb and the cooling water passage (refrigerant passage) 8. 75, a cooling water introduction port 77, and a cooling water discharge port 78.

  As shown in FIG. 12, through-holes through which the tie rods 90 are inserted are arranged at the four corners of the stack portion 20, current collector plates 30 and 40, insulating plates 50 and 60, and end plates 70 and 80. The tie rod 90 is screwed with a nut (not shown) to a male screw portion formed at an end portion thereof, and the inside of the fuel cell stack 200 (stack portion 20) is fastened by the end plates 70 and 80. The load for forming the stack acts in the stacking direction of the single fuel cell (cell unit) 1 (MEA 9), and holds the single fuel cell (cell unit) 1 in a pressed state.

As shown in FIG. 12, the tie rod 90 is formed of a rigid material, for example, a metal material such as steel, and an insulated surface to prevent an electrical short circuit between the fuel cell single cells 201. Part. The number of tie rods 90 installed is not limited to four (four corners). The fastening mechanism of the tie rod 90 is not limited to screwing, and other means may be applied. As shown in FIGS. 1, 13, and 14, the fuel cell single cell (cell unit) 1 is as described above. Further, it is desirable to have a configuration that includes the MEA 9, the separators 5a and 5b, and further includes a gasket (not shown). The MEA 9 includes an electrolyte membrane 2, a fuel electrode side electrode (catalyst layer 3 a and gas diffusion layer 4 a) and an oxygen electrode side electrode (catalyst layer 3 b and gas diffusion layer 4 b) disposed with the electrolyte membrane 2 interposed therebetween. Separator 5a, 5b is arrange | positioned on the outer surface of MEA9. The separator 5 a has a flow path 5 aa for circulating the fuel gas 5 ag and is connected to a fuel gas inlet 71 and a fuel gas outlet 72 arranged in the end plate 70. The separator 5 b has a flow path 5 bb for allowing the oxidant gas 5 bg to flow, and is connected to an oxidant gas inlet 74 and an oxidant gas outlet 75 arranged in the end plate 80.

  As shown in FIGS. 1, 13, and 14, the separators 5 a and 5 b have a flow path 8 for circulating the cooling water 8 w, and a cooling water inlet 77 arranged in the end plates 70 and 80. And a cooling water discharge port 78.

  Next, the gasket is a seal member disposed so as to surround the outer periphery of the electrode positioned on the surface of the MEA 9 and is fixed to the outer surface of the electrolyte membrane 2 of the MEA 9 via an adhesive layer (not shown). You may have a structure. The gasket has a function of ensuring the sealability between the separator 5 and the MEA 9. Note that the adhesive layer used as necessary preferably corresponds to the shape of the gasket and is arranged in a frame shape on the entire peripheral edge of the electrolyte membrane in consideration of securing adhesiveness.

  Further, as shown in FIG. 12, in the fuel cell stack 200 using the conductive member of the present invention, a manifold (anode (fuel gas 5ag), cathode (oxidation) formed through the current collector plates 30 and 40 is formed. In the preferred embodiment, the intermediate layer 32 found in the present invention is also formed on the inner wall of the penetrating portion of the agent gas 5bg) and the inlet and outlet of each of the cooling water 8w for a total of 6 locations). That is, since no electrical conductivity is required on the inner wall of the penetrating portion of the manifold, it is desirable to form the intermediate layer (Cr layer) 32 without providing a surface treatment layer such as gold plating. This is extremely effective in that corrosion of the base material at the penetrating portion of the manifold can be effectively prevented.

  The above is the outline of the configuration of the fuel cell stack 200 using the conductive member of the present invention. In addition to the metal separator 5 and the current collector plates 30 and 40, the components of the fuel cell that require conductivity and corrosion resistance About (conductive member), the structure of this invention can be employ | adopted. As a result, it is possible to reduce the thickness and weight of the fuel cell component (conductive member), and thus the fuel cell stack, and contribute to improving the output density. Furthermore, since it leads to cost reduction, it is also useful as a battery element technology to be mounted on a fuel cell vehicle that is strongly demanded for price reduction.

  The manufacturing method of the fuel cell of the present invention is not particularly limited (except for the manufacturing method of the intermediate layer 32 described above) in particular, and can be manufactured by appropriately referring to conventionally known knowledge in the field of fuel cells. It is.

  The type of the fuel gas 5ag (hydrogen-containing gas) used when operating the fuel cell has been described by taking hydrogen as an example in the above description, but is not particularly limited. In addition to hydrogen, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, secondary butanol, tertiary butanol, dimethyl ether, diethyl ether, ethylene glycol, and diethylene glycol can be used. Of these, hydrogen and methanol are preferred because they can increase the output.

  Furthermore, a fuel cell stack 200 having a structure in which a plurality of membrane electrode assemblies (MEA 9) are stacked and connected in series via a metal separator 5 may be formed so that a desired voltage or the like can be obtained by the fuel cell ( 11 and 12). The shape of the fuel cell is not particularly limited, and may be determined as appropriate so that desired battery characteristics such as voltage can be obtained.

  Although it does not restrict | limit especially as a use of the fuel cell of this invention, Since it is excellent in electric power generation performance, it is preferable to use as a drive power supply in vehicles, such as a motor vehicle.

  The PEFC cell unit 1 and the fuel cell stack 200 described above use a metal separator 5 made of a conductive member having excellent conductivity and corrosion resistance. Therefore, the cell unit 1 and the fuel cell stack 200 of the PEFC are excellent in output characteristics and durability, and can maintain good power generation performance over a long period of time. In the PEFC cell unit 1 in the form shown in FIG. 1, the metal separator 5 is formed in a concavo-convex shape by subjecting a flat conductive member to a press treatment. However, it is not limited only to such a form. For example, the concave and convex shapes constituting the gas flow paths 5ag and 5bg and the refrigerant flow path 8 are formed in advance by performing a cutting process on a flat metal plate (metal base 31), and the above-described technique is formed on the surface thereof. By forming the conductive carbon layer 33 (and the intermediate layer 32 if necessary), the metal separator 5 may be used.

  The PEFC cell unit 1 of this embodiment and the fuel cell stack 200 using the same can be mounted on a vehicle as a driving power source, for example.

  FIG. 9 is a conceptual diagram of a vehicle equipped with the fuel cell stack of the above-described embodiment. As shown in FIG. 9, in order to mount the fuel cell stack 200 on a vehicle such as the fuel cell vehicle 210, for example, the fuel cell stack 200 may be mounted under the seat at the center of the vehicle body of the fuel cell vehicle 210. If it is installed under the seat, the interior space and the trunk room can be widened. Depending on the case, the place where the fuel cell stack 200 is mounted is not limited to under the seat, but may be a lower part of the rear trunk room or an engine room in front of the vehicle 210. Thus, the vehicle 210 equipped with the PEFC cell unit 1 and the fuel cell stack 200 of the above-described form is also included in the technical scope of the present invention. The above-described PEFC cell unit 1 and fuel cell stack 200 are excellent in output characteristics and durability. Therefore, a highly reliable fuel cell vehicle 210 can be provided over a long period of time.

  Hereinafter, although the effect by this invention is demonstrated using an Example and a comparative example, the technical scope of this invention is not limited to these Examples.

[Example 1] (First Embodiment)
After using a separator plate (metal substrate 31) made of aluminum (or an aluminum alloy) with a thickness of 200 μm and ultrasonically cleaning in ethanol solution for 3 minutes as a pretreatment, the metal substrate 31 is further placed in a vacuum chamber, Ion bombardment with Ar gas was performed to remove the oxide film on the surface. Both the pretreatment and the ion bombardment treatment were performed on both surfaces of the metal substrate 31. In addition, aluminum A1050 was used for the metal base material 31 made of aluminum (or aluminum alloy) (the same applies to Example 2 and Reference Example 5).

  Next, a Cr film having a film thickness of 0.1 μm is applied by using unbalanced magnetron sputtering (UBMS) method while using Cr as a target and applying an initial 50 V negative bias voltage to the aluminum plate (metal substrate 31). (Intermediate layer A) is formed, and then the bias voltage is gradually increased and finally 200 V is applied (see FIG. 20B for the application pattern), while a 1 μm-thick Cr coating (on the basis) An intermediate layer 32 including the intermediate layer A) was formed on the Cr film.

  Next, while applying a negative bias voltage of 150 V to the metal base material 31 by the UBMS method on the intermediate layer 32, solid graphite is used as a target, and the metal base material 31 on which the intermediate layer 32 is formed is formed. A conductive carbon layer 33 having a thickness of 0.2 μm was formed on both surfaces.

[Example 2] (Second Embodiment)
A separator plate (metal substrate 31) made of aluminum (or aluminum alloy) and having a thickness of 200 μm was used, and a lapping treatment was performed as a pretreatment. The lapping treatment here is an efficient polishing by embedding abrasive grains in an elastic body with elasticity and adhesiveness and sliding the surface of the abrasive material containing aqueous solution on the workpiece (workpiece) at high speed. This is a process for obtaining a smooth mirror surface. The surface roughness (Ra) was 0.3. Then, after ultrasonically cleaning for 3 minutes in an ethanol solution, the metal substrate 31 was further placed in a vacuum chamber and subjected to ion bombardment with Ar gas to remove the oxide film on the surface. Both the pretreatment and the ion bombardment treatment were performed on both surfaces of the metal substrate 31.

  Next, by using unbalanced magnetron sputtering (UBMS) method, using Cr as a target and applying a constant negative bias voltage (50 V) to the aluminum plate (metal substrate 31), the metal substrate A Cr film (intermediate layer 32) having a film thickness of 200 nm was formed on both surfaces of 31.

  Next, solid graphite is used as a target while applying a negative bias voltage of 150 V to the metal substrate 31 on the intermediate layer 32 by the UBMS method. A 2 μm conductive carbon layer 33 was formed.

[Comparative Example 1]
Example 2 is the same as Example 2 except that the intermediate layer 32 having a film thickness of 200 nm is formed with a constant negative bias voltage (50 V) with respect to the aluminum plate (metal substrate 31) without performing a lapping process in the pretreatment. Similarly, a conductive carbon layer 33 having a thickness of 0.2 μm was formed on both surfaces of the metal base 31 on which the intermediate layer 32 was formed.

[Comparative Example 2]
The bias voltage was applied so that the method of applying the bias voltage at the time of forming the intermediate layer 32 was opposite to that in Example 1. Specifically, a Cr film (intermediate layer 32) having a film thickness of 1.1 μm was formed on both surfaces of a separator plate (metal substrate 31) made of aluminum (or an aluminum alloy) and having a film thickness of 200 μm obtained in the same manner as in Example 1. When forming, a Cr film (intermediate layer A) having a film thickness of 1.0 μm is formed on an aluminum plate (metal base 31) while applying a negative bias voltage at an initial voltage of 200V, and then the bias voltage is gradually increased. While reducing and finally applying 50 V (see the reverse pattern of FIG. 20B for the applied pattern), a 0.1 μm-thick Cr film (including the intermediate layer A on the Cr film) on both surfaces of the metal base 31 32). Other than that was carried out similarly to Example 1, and formed the conductive carbon layer 33 with a film thickness of 0.2 micrometer on both surfaces of the metal base material 31 in which the intermediate | middle layer 32 was provided.

[Reference Example 1]
A stainless steel (SUS316L) plate (thickness: 100 μm) was prepared as a constituent material of the metal base 31 constituting the conductive member. This stainless steel plate (metal substrate layer 31) was subjected to ultrasonic cleaning in an aqueous ethanol solution for 3 minutes as a pretreatment. Next, the cleaned stainless steel plate was placed in a vacuum chamber, and ion bombardment with Ar gas was performed to remove the oxide film on the surface. The pretreatment (cleaning) and ion bombardment described above were both performed on both surfaces of the stainless steel plate.

  Subsequently, by applying an unbalanced magnetron sputtering (UBMS) method and applying a negative bias voltage of 50 V to the stainless steel plate with Cr as a target, each of the stainless steel plates has a thickness of 0.2 μm. An intermediate layer 32 made of Cr was formed.

  Furthermore, by applying a negative bias voltage of 100 V to the stainless steel plate (metal base material layer 31) using solid graphite as a target by the UBMS method, on the intermediate layer 32 on both surfaces of the stainless steel plate, Conductive carbon layers 33 each having a thickness of 0.2 μm were formed. As a result, the conductive member of Reference Example 1 was produced.

[Reference Example 2]
Except that the magnitude (absolute value) of the negative bias voltage applied when forming the conductive carbon layer 33 was set to 140 V, the conductive member of the present Reference Example 2 was manufactured in the same manner as the Reference Example 1 described above. Produced.

[Reference Example 3]
Except that the magnitude (absolute value) of the negative bias voltage applied when forming the conductive carbon layer 33 was set to 300 V, the conductive member of the present Reference Example 3 was manufactured in the same manner as the Reference Example 1 described above. Produced.

[Reference Example 4]
The conductive member of Reference Example 4 was manufactured in the same manner as Reference Example 1 except that the magnitude (absolute value) of the negative bias voltage applied when forming the conductive carbon layer 33 was 450V. Produced.

[Reference Example 5]
A conductive member of Reference Example 5 was produced in the same manner as Reference Example 2 described above except that the material constituting the metal base 31 was aluminum (aluminum A1050).

[Reference Example 6]
A conductive member of Reference Example 6 was produced by the same method as Reference Example 2 described above except that the method of forming the intermediate layer 32 and the conductive carbon layer 33 was an arc ion plating method.

[Reference Example 7]
Except that the intermediate layer 32 is not formed and the conductive carbon layer 33 is formed directly on the stainless steel plate (metal substrate 31) by the ECR sputtering method, this Reference Example 7 is used in the same manner as in Reference Example 1 described above. A conductive member was prepared.

[Comparative Example 3]
The reference example described above, except that the intermediate carbon layer 32 was not formed and the conductive carbon layer 33 was formed directly on the stainless steel plate (metal substrate 31), and no negative bias voltage was applied during the formation. 1 was used to produce a conductive member of Comparative Example 3.

[Comparative Example 4]
A conductive member of Comparative Example 4 was produced in the same manner as in Reference Example 1 described above, except that a negative bias voltage was not applied when the conductive carbon layer 33 was formed.

[Comparative Example 5]
A conductive member of Comparative Example 5 was produced by the same method as in Reference Example 1 described above except that the method of forming the intermediate layer 32 and the conductive carbon layer 33 was a plasma chemical vapor deposition (CVD) method. .

[Comparative Example 6]
A conductive member of this comparative example 6 was produced by the same method as the reference example 1 described above except that the method of forming the intermediate layer 32 and the conductive carbon layer 33 was an ionized vapor deposition method.

[Comparative Example 7]
The above-mentioned reference except that the method of forming the conductive carbon layer 33 without forming the intermediate layer 32 is a thermal chemical vapor deposition (CVD) method, and the thickness of the conductive carbon layer 33 is 0.08 μm. In the same manner as in Example 1, a conductive member of Comparative Example 7 was produced. In addition, the film-forming temperature at the time of implementing thermal CVD was set to 850 degreeC.

[Measurement of contact resistance]
For the conductive members produced in Examples 1 and 2, Reference Examples 1 to 7 and Comparative Examples 1 to 7, the contact resistance in the stacking direction of the conductive members was measured. Specifically, as shown in FIG. 10A, a pair of gas diffusion is performed on both sides of the conductive member (metal separator 5) formed in Example 12, Reference Examples 1 to 7 and Comparative Examples 1 to 7 above. A laminate including the electrodes, sandwiched between the base materials (gas diffusion layers 4a, 4b), and further sandwiched on both sides of the obtained laminate with a pair of electrodes (catalyst layers 3a, 3b), connected to a power source at both ends. The whole body was held with a load of 1 MPa to constitute a measuring device. A contact resistance value of the laminate was calculated from an energization amount and a voltage value when a constant current of 1 A was passed through the measuring apparatus and a load of 1 MPa was applied.

  Moreover, after measuring a contact resistance value above, the immersion test with respect to acidic water was done, and the contact resistance value was measured similarly. In addition, as an immersion test, specifically, each conductive member (metal separator 5) formed into a film in Examples 1 and 2, Reference Examples 1 to 7 and Comparative Examples 1 to 7 is 30 mm × 30 mm in size. Cut out and immersed in acidic water at a temperature of 80 ° C. (Examples 1 and 2 and Comparative Examples 1 and 2 are both pH 6 or less, Reference Examples 1 to 7 and Comparative Examples 3 to 7 are pH 4 or less) for 100 hours, and immersion test The front and back contact resistance values were measured.

  The obtained results are shown in Tables 1 and 2 below. Moreover, the graph corresponding to the result regarding the contact resistance shown to Table 1, 2 is shown to FIG. 10B and FIG. 10C. In the graph shown in FIG. 10C, the vertical axis is a logarithmic scale, and the value of the contact resistance on the vertical axis is shown as a relative value.

  As shown in Tables 1 and 2 and FIGS. 10B and 10C, in the case of the conductive members produced in Examples 1 and 2, the metal base 31 was made of a metal base despite being easily corroded. Compared with the case of the other reference example 5 which uses aluminum for the material layer 31, and the comparative examples 1 and 2, even after an immersion test, a contact resistance is suppressed to a still smaller value. Moreover, in the case of the electrically-conductive member produced in Example 1, 2, the contact resistance (corrosion resistance) which is inferior to the other reference examples 1-4, 6-7 which use the stainless steel for the metal base material 31 is hold | maintained. It was confirmed that it was possible.

[Measurement of Al elution]
About the electroconductive member produced in said Example 1 and Comparative Example 1, the quantitative analysis of Al was performed for the acid solution after the immersion test of the said contact resistance measurement by ICP-MS.

  The obtained results are shown in Table 1 below. Although the conductive member of Example 1 uses aluminum that is easily corroded in the metal base layer 31, even when compared with the conductive member of Comparative Example 1 that uses the same aluminum for the metal base layer 31, The anticorrosion effect of aluminum (metal base layer 31) can be enhanced. Specifically, even after the immersion test for measuring the contact resistance, the conductivity of Example 1 in which the negative bias voltage at the time of forming the intermediate layer is changed from at least a low value to a high value in the dry film forming method. For the member, it was confirmed that the elution amount of Al was 500 ppb, which was suppressed to an extremely small value compared to the elution amount of Al of 1500 ppb of the conductive member of Comparative Example 1 with a constant bias voltage.

[Measurement of R value]
About the electrically-conductive member produced in each said reference example 1-7 and each comparative example 3-7, the R value of the conductive carbon layer 33 was measured. Specifically, first, the Raman spectrum of the conductive carbon layer 33 was measured using a microscopic Raman spectrometer. Then, the peak intensity of the bands (D-band) located 1300~1400cm ^-1 _{(I D),} the peak area ratio of the peak intensity _{(I G)} of band (G-band) located 1500~1600cm ^-1 ( I _D / I _G ) was calculated and used as the R value. The obtained results are shown in Table 2 below.

As shown in Table 2, D band peak intensity (I _D ) and G band peak intensity (I _G ) measured by Raman scattering spectroscopic analysis of the conductive carbon layer 33 in the conductive members prepared in Reference Examples 1 to 7 The intensity ratio R (I _D / I _G ) value (indicated as “D / G” in Table 1. In the following, simply abbreviated as “R value”) is 1.3 or more. there were. On the other hand, the R value (“D / G” in Table 1) of the conductive carbon layer 33 in the conductive members produced in Comparative Examples 3 to 7 was less than 1.3.

[Measurement of hydrogen atom content in conductive carbon layer 33]
About the electrically-conductive member produced in each said reference example 1-7 and each comparative example 3-7, content of the hydrogen atom in the conductive carbon layer 33 was measured by the elastic recoil scattering analysis method (ERDA). The obtained results are shown in Table 2 below.

[Measurement of Vickers Hardness (Hv) of Conductive Carbon Layer 33]
About the electrically-conductive member produced in said each reference examples 1-7 and each comparative examples 3-7, the Vickers hardness (Hv) of the conductive carbon layer 33 was measured by the nanoindentation method. The obtained results are shown in Table 2 below.

  As shown in Table 2, the Vickers hardness of the conductive carbon layer 33 in the conductive members produced in Reference Examples 1 to 7 was all 1500 Hv or less.

In Table 1, “Number of protruding particles 33a per 100 μm ² ” is the number of particles having a diameter of 200 to 500 nm on the outermost surface.

  In Example 1 and Example 2, the column diameter of the columnar crystals is large, and the contact resistance before and after immersion is low. On the other hand, in Comparative Example 1 and Comparative Example 2, it can be seen that the column diameter of the columnar crystals is small and the contact resistance after immersion is increased.

  The reason why the column diameter of the columnar crystals increases when the bias voltage is increased from a low value to a high value in Example 1 is considered as follows. Increasing the bias voltage increases the ion assist effect of ionized Ar ions. As a result, atoms are deposited with high energy on the outermost surface of the film, so the disordered part (interface) of the atomic arrangement is reduced, and the region of uniform atomic deposition is expanded, resulting in a coarse columnar form. .

  The reason why the column diameter of the columnar crystals is increased by adding a polishing step as a pretreatment in Example 2 is considered as follows. When the surface roughness is reduced by the polishing process, the orientation difference between adjacent columnar crystals is reduced, so that the adjacent columnar crystals are easily combined to grow as coarse columnar crystals. On the other hand, when the surface roughness is large, if there is an uneven portion, columnar crystals are likely to grow using that as a nucleation site.

  The reason why the column diameter of the columnar crystals decreases when the bias voltage is changed from a high value to a low value in Comparative Example 2 is considered as follows. When the bias voltage is high, the metal substrate interface is strongly sputtered and the substrate roughness is deteriorated. This is presumably because nucleation sites increase and many columnar crystals with a small column diameter grow.

  In addition to this supplemental example, as a method of increasing the column diameter of the columnar crystals, a method of increasing the pressure in the apparatus during film formation, a method of increasing the film formation temperature, or the like may be used.

  Contrast the drawings in which the boundary between the columnar crystal structure Cr layer (columnar intermediate layer 32) and the conductive carbon layer 33 (DLC layer) in the film formation obtained in Comparative Example 1 and Example 1 is different. Show.

First, FIG. 13a and FIG. 13b are drawings of SEM observation of the surface (outermost surface) of the conductive member of Comparative Example 1 (FIG. 13a) and drawings of SEM observation of the surface (outermost surface) of the conductive member of Example 1 (FIG. 13). 13b). Thereby, in Comparative Example 1 and Example 1, the presence or absence of the protruding particles 33a on the outermost surface of the conductive member can be easily confirmed, and at least 30 or more protruding particles 33a exist per 100 μm ^2. It is also easy to check whether or not (see Table 1).

  Next, FIGS. 14 a and 14 b are an enlarged view (FIG. 14 a) of an SEM observation (FIG. 13 a) of the surface (outermost surface) of the conductive member of Comparative Example 1 and the surface of the conductive member of Example 1 ( It is an enlarged view (FIG. 14b) of drawing (FIG. 13b) of SEM observation of the outermost surface. Thus, in Comparative Example 1 and Example 1, the presence or absence of the protruding particles 33a on the outermost surface of the conductive member can be easily confirmed, and the protruding particles 33a having a diameter of 200 to 500 nm on the outermost surface In addition, it is possible to confirm that the minute particles 33b having a diameter of 50 to 100 nm are mixed and the sizes of the respective particles (see Table 1).

  Next, FIG. 15a and FIG. 15b are TEM observations of the cross section of the conductive member of Comparative Example 1 (mainly the cross section of the Cr layer (columnar intermediate layer 32) having a columnar crystal structure and the conductive carbon layer 33 (DLC layer)). FIG. 15A and a cross-sectional view of the conductive member of Example 1 (mainly a cross-sectional portion of a Cr layer (columnar intermediate layer 32) and a conductive carbon layer 33 (DLC layer) having a columnar crystal structure)) It is drawing (FIG. 15b). Thereby, the thickness of the columnar crystal column in the cross section of the intermediate layer 32 can be measured in Comparative Example 1 and Example 1, and the average value of the columnar crystal column thickness in the cross section of the intermediate layer 32 is 200. It can also be confirmed whether it is in the range of ˜500 nm. Further, the height of the outermost conductive carbon layer 33 (DLC layer) with respect to the peripheral portion of the protruding particles 33a can be measured, and this height protrudes in the range of 100 to 500 nm with respect to the peripheral portion. It can also be confirmed. In addition, the film thickness of the Cr intermediate layer 32 can be measured, and it can be easily confirmed that the film thickness is in the range of 0.02 to 5 μm. In addition, a column having a thickness of 200 to 500 nm in the outermost layer can be easily measured (specified), and the column having the thickness is what percentage of the entire thickness of the intermediate layer 32 with respect to the direction of the metal substrate 31 from the outermost layer. In particular, it can be easily measured whether or not it is present at 5 to 95% (see Table 1).

  Next, FIGS. 16a and 16b are SEM observations of the cross section of the conductive member of Comparative Example 1 (mainly the cross section of the Cr layer (columnar intermediate layer 32) and the conductive carbon layer 33 (DLC layer) having a columnar crystal structure). SEM observation of the cross-sectional view (Fig. 16a) and the cross-section of the conductive member of Example 1 (mainly the cross-sectional portion of the Cr layer (columnar intermediate layer 32) and the conductive carbon layer 33 (DLC layer) having a columnar crystal structure)) It is drawing (FIG. 16b). Thereby, the thickness of the columnar crystal column in the cross section of the intermediate layer 32 can be measured in Comparative Example 1 and Example 1, and the average value of the columnar crystal column thickness in the cross section of the intermediate layer 32 is 200. It can also be confirmed whether it is in the range of ˜500 nm. In addition, the film thickness of the Cr intermediate layer 32 can be measured, and it can be easily confirmed that the film thickness is in the range of 0.02 to 5 μm. In addition, a column having a thickness of 200 to 500 nm in the outermost layer can be easily measured (specified), and the column having the thickness is what percentage of the entire thickness of the intermediate layer 32 with respect to the direction of the metal substrate 31 from the outermost layer. In particular, it can be easily measured whether or not it is present at 5 to 95% (see Table 1).

Next, FIG. 17 is also a drawing of SEM observation of the surface (outermost surface) of the conductive member of Example 1, and FIG. 19 is a drawing of SEM observation of the surface (outermost surface) of the conductive member of Example 2. From now on, the presence or absence of the protruding particles 33a on the outermost surface of the conductive member can be easily confirmed, and it can also be easily confirmed whether or not at least 30 protruding particles 33a are present per 100 μm ² (Table). 1). In FIG. 17 and FIG. 19, there are 50 or more particles having a diameter of 300 to 500 nm (projecting particles 33a) per 100 μm ^{2 in} a square area surrounded by a black line frame in the figure. Was confirmed. FIG. 18 is an enlarged view of FIG. Thereby, the diameter (size: red line double arrow (⇔) corresponds to the measurement range) of the protruding particles 33a of the outermost conductive carbon layer 33 (DLC layer) can be measured (see Table 1). .

(Note) In the film formation methods in Table 2, UBM ¹⁾ is an abbreviation for “UBM sputtering”, ECR ³⁾ is an abbreviation for “ECR sputtering”, and ion ²⁾ is an abbreviation for “ion plating”. Yes, plasma ⁴⁾ is an abbreviation for “plasma CVD”.

1,201 Single polymer fuel cell (PEFC) single cell (unit cell),
2 electrolyte membrane (solid polymer electrolyte membrane),
3 catalyst layer,
3a Anode catalyst layer (fuel electrode side electrode catalyst layer),
3b Cathode catalyst layer (oxygen electrode side electrode catalyst layer),
4 Gas diffusion layer (GDL),
4a Anode gas diffusion layer (fuel electrode side gas diffusion layer),
4b Cathode gas diffusion layer (oxygen electrode side gas diffusion layer),
5 Separator (metal separator),
5a Anode separator (fuel electrode side separator),
5b Cathode separator (oxygen electrode side separator),
5aa Fuel gas channel (hydrogen-containing gas channel),
5ag fuel gas (hydrogen gas, hydrogen-containing gas, etc.),
5bb oxidizing gas channel (oxygen gas channel),
5 bg oxidant gas (air, oxygen gas, etc.),
6 metal substrate,
7 Layer for surface treatment,
7a reaction surface,
7b Cooling surface,
8 Cooling water channel (refrigerant channel),
8w cooling water (refrigerant),
9 Membrane-electrode assembly (MEA),
10 Fuel cell stack,
20 stack part (stacked stack),
30, 40 current collector plate,
31 metal substrate,
32 middle class,
33 conductive carbon layer (metal separator),
33a Projecting particles on the outermost surface of the conductive carbon layer;
33b microparticles,
37, 47 output terminals,
50, 60 insulation plate,
70 fuel electrode side end plate,
80 oxygen electrode side end plate,
71 Fuel gas inlet,
72 Fuel gas outlet,
74 Oxidant gas inlet,
75 Oxidant gas outlet,
77 Cooling water inlet,
78 Cooling water outlet,
90 tie rods,
200 Fuel cell (stack),
210 vehicles,
H ₁ , H ₂ , H ₃ height of protruding particles,
The thickness (width, column diameter) of the W ₁ , W ₂ , W ₃ intermediate layer.

Claims (14)

In the dry film-forming method, selected from the group consisting of Group 4 metals, Group 5 metals, Group 6 metals, and carbides, nitrides, and carbonitrides of the periodic table on a metal substrate. A step of forming an intermediate layer composed of at least one kind, and a step of forming a conductive carbon layer on the intermediate layer,
A method for producing a conductive member, comprising changing a negative bias voltage at the time of forming an intermediate layer from at least a low value to a high value. After performing the step of polishing the surface of the metal substrate and the step of removing the oxide film on the surface of the substrate , the group 4 metal and group 5 of the periodic table are formed on the surface of the substrate. A step of forming an intermediate layer by sputtering using at least one selected from the group consisting of a metal of the above, a Group 6 metal, and a carbide, nitride and carbonitride thereof , on the intermediate layer, And a step of forming a conductive carbon layer by a dry film forming method. Selected from the group consisting of a metal substrate, a metal of Group 4 of the periodic table, a metal of Group 5 and a metal of Group 6 and their carbides, nitrides and carbonitrides on the metal substrate An intermediate layer made of at least one kind, and a conductive member coated with a conductive carbon layer on the intermediate layer,
The intermediate layer has a columnar crystal structure , a columnar protrusion exists on the surface of the columnar crystal structure on the conductive carbon layer side, and a convex shape along the shape of the columnar protrusion on the surface of the conductive carbon layer A conductive member characterized in that a portion exists.   4. The conductive member according to claim 3, wherein in the intermediate layer, an average value of columnar crystal column thickness in a cross section of the intermediate layer is 200 to 500 nm.   In the intermediate layer, the thickness of the columnar crystal in the cross section of the intermediate layer is 200 to 500 nm, and the columnar crystal having the thickness is an intermediate layer film on the conductive carbon layer side of the entire intermediate layer. 5. The conductive member according to claim 3, wherein 5 to 95% of the entire thickness is present. The surface of the conductive carbon layer, any one of claims 3-5, characterized in that said convex portion having a diameter of 200 to 500 nm, said convex portion of the diameter of 50~100nm are mixed The conductive member according to Item 1. The conductive member according to claim 6, wherein at least 30 convex portions having a diameter of 200 to 500 nm are present per 100 μm ² .   8. The conductive member according to claim 3, wherein the intermediate layer is at least one selected from the group consisting of chromium, titanium, carbides thereof, and nitrides thereof. The intensity ratio R (I _D / I _G ) between the D band peak intensity (I _D ) and the G band peak intensity (I _G ) measured by Raman scattering spectroscopy of the conductive carbon layer is 1.3 or more. The conductive member according to any one of claims 3 to 8, wherein   10. The conductive member according to claim 3, wherein an average peak measured by rotational anisotropy measurement by Raman scattering spectroscopic analysis of the conductive carbon layer exhibits a two-fold symmetry pattern. .   The conductive member according to claim 3, wherein the intermediate layer is formed by a sputtering method.   The conductive member according to claim 3, wherein the conductive member is used in a wet environment and an energized environment.   The separator for fuel cells comprised from the electrically-conductive member of any one of Claims 3-12. A polymer electrolyte membrane, a pair of anode catalyst layer and cathode catalyst layer sandwiching the polymer electrolyte membrane, and a membrane electrode assembly including a pair of anode gas diffusion layer and cathode gas diffusion layer sandwiching them;
A polymer electrolyte fuel cell having a pair of anode separator and cathode separator sandwiching the membrane electrode assembly,
14. At least one of the anode separator or the cathode separator is the fuel cell separator according to claim 13 , wherein the fuel cell separator is formed in a concavo-convex shape, and the convex portion is the membrane electrode joint. A solid polymer fuel cell, wherein the solid polymer fuel cell is in contact with a body, and the concave portion serves as a gas flow path for circulating fuel gas or oxidant gas.