JP5342518B2 - Method for producing titanium fuel cell separator - Google Patents

Description

  The present invention relates to a method for producing a titanium fuel cell separator used in a fuel cell.

  Unlike primary batteries such as dry batteries and secondary batteries such as lead-acid batteries, fuel cells that can continuously extract power by continuing to supply fuel such as hydrogen and oxidants such as oxygen have high power generation efficiency. It is expected to be an energy source that covers a wide range of applications and scales because it is not significantly affected by the size of the system and has little noise and vibration. Specifically, the fuel cell includes a polymer electrolyte fuel cell (PEFC), an alkaline electrolyte fuel cell (AFC), a phosphoric acid fuel cell (PAFC), a molten carbonate fuel cell (MCFC), and a solid oxide. It has been developed as a type fuel cell (SOFC) and biofuel cell. In particular, solid polymer fuel cells are being developed for mobile devices such as fuel cell vehicles, household fuel cells (household cogeneration systems), mobile phones and personal computers.

  A polymer electrolyte fuel cell (hereinafter referred to as a fuel cell) is a single cell in which a solid polymer electrolyte membrane is sandwiched between an anode electrode and a cathode electrode, and a groove serving as a gas (hydrogen, oxygen, etc.) flow path. Is formed as a stack in which a plurality of the single cells are overlapped with each other through an electrode called a separator (also called a bipolar plate). The output of the fuel cell can be increased by increasing the number of cells per stack.

  Since the separator for a fuel cell is also a component for taking out the generated current to the outside of the fuel cell, the material has a contact resistance (a voltage drop occurs due to an interfacial phenomenon between the electrode and the separator surface). Is required to be maintained for a long time during use as a separator. Furthermore, since the inside of the fuel cell is in an acidic atmosphere, the separator is also required to have high corrosion resistance.

  In order to satisfy these requirements, various separators have been proposed which are formed by cutting a graphite powder molded body or a mixture of graphite and resin mixture. Although these have excellent corrosion resistance, they are inferior in strength and toughness, and therefore may be damaged when subjected to vibration or impact. Therefore, various separators based on metal materials have been proposed and variously proposed.

  Examples of the metal material having both corrosion resistance and conductivity include Au and Pt. Conventionally, a metal material such as an aluminum alloy, stainless steel, nickel alloy, titanium alloy, etc., which can be thinned and has excellent workability and high strength, is coated with a noble metal such as Au or Pt. A separator imparted with corrosion resistance and conductivity has been studied. However, these noble metal materials are very expensive and therefore expensive.

In order to solve such a problem, a method of manufacturing a metal separator that does not use a noble metal material has been proposed.
For example, a method of forming an intermediate layer and a conductive thin film on the surface of the oxide film of the substrate itself by a vapor deposition method (Patent Document 1), a portion made of a metalloid element, carbon, etc. There has been proposed a method (Patent Document 2) in which a surface treatment layer composed of a portion made of is formed by a vapor deposition method.

  Also, a method of forming a conductive carbon film on the surface of the substrate by chemical vapor synthesis or sputtering (Patent Document 3), or a coating layer comprising an amorphous carbon layer and a conductive portion on the surface of the substrate Has been proposed (Patent Document 4) in which a film is formed by sputtering, filterless arc ion plating, or the like.

Japanese Patent No. 4147925 Japanese Patent Laid-Open No. 2004-14208 JP 2007-207718 A JP 2008-204876 A

However, the techniques disclosed in Patent Documents 1, 2, and 3 are such that an intermediate layer, a conductive thin film, and the like are formed on the surface of the base material by a vapor deposition method. We are concerned that we are weak.
Further, in Patent Document 4, since the coating layer made of carbon is formed on the surface of the base material by a vapor deposition method, and the coating layer is directly formed on the surface of the base material, The adhesion may be very weak.
In addition, when the adhesiveness of each layer, such as an electroconductive thin film which influences electroconductivity and corrosion resistance, and a base material is weak, the said each layer cannot be stably maintained on a base material. Therefore, the low adhesion between the base material and the respective layers adversely affects the conductivity durability (durability: property of maintaining conductivity for a long time) and corrosion resistance of the separator.

  This invention is made | formed in view of the said subject, The subject is providing the manufacturing method of the fuel cell separator made from titanium in which the carbon layer has coat | covered the base-material surface in the state with high adhesiveness. is there.

  The present inventors use an organic adhesive containing carbon powder to bond a carbon sheet to a base material made of pure titanium or a titanium alloy, and then press and heat-treat the base material. And found that the adhesion between the carbon layer and the carbon layer (layer composed of a carbon sheet) can be improved.

  In order to solve the above problems, a method for producing a titanium fuel cell separator according to the present invention is a method for producing a titanium fuel cell separator in which a carbon layer is provided on a substrate surface made of pure titanium or a titanium alloy, An adhesion step of adhering a carbon sheet to be the carbon layer to the substrate surface using an organic adhesive, a pressing step of pressing the substrate after the adhesion step, and heat-treating the substrate after the pressing step A heat treatment step, wherein the organic adhesive contains carbon powder.

As described above, the method for manufacturing a titanium fuel cell separator according to the present invention includes a carbon atom in a carbon powder and a carbon sheet in the heat treatment step, because the organic adhesive that bonds the base material and the carbon sheet contains carbon powder. These carbon atoms are rearranged so that they are chemically bonded together. And the titanium of the base material, the carbon sheet, and the carbon of the carbon powder react in the heat treatment step, and the intermediate layer made of titanium carbide having a concavo-convex structure between the base material and the carbon layer (layer constituted by the carbon sheet). Will be formed.
Therefore, a separator with greatly improved adhesion between the substrate and the carbon layer can be produced.

  In the method for producing a titanium fuel cell separator according to the present invention, the carbon powder is preferably graphite powder, and the average particle size is preferably 0.5 to 20 μm.

  Thus, when carbon powder is graphite powder, carbon powder is easy to grind | pulverize in a press process, and the said grind | pulverized carbon powder arranges densely in the interface of a base material and a carbon sheet. Therefore, when the rearrangement of the carbon atom of the carbon powder and the carbon atom of the carbon sheet in the heat treatment process occurs appropriately, both are bonded more firmly. As a result, by appropriately forming the intermediate layer made of titanium carbide in the heat treatment step, it is possible to manufacture a separator in which the adhesion between the base material and the carbon layer is further improved.

Moreover, since the graphite powder is appropriately pulverized in the pressing step because the average particle diameter of the graphite powder is 0.5 to 20 μm, a separator with further improved adhesion between the base material and the carbon layer is manufactured. Can do.

In the method for producing a titanium fuel cell separator according to the present invention, the heat treatment in the heat treatment step is preferably performed in a non-oxidizing atmosphere having an oxygen partial pressure of 1.3 × 10 ⁻¹ Pa or less.

Thus, by performing the heat treatment in the heat treatment step in a non-oxidizing atmosphere having an oxygen partial pressure of 1.3 × 10 ⁻¹ Pa or less, the carbon of the carbon sheet reacts with oxygen in the atmosphere (generation of carbon dioxide). The situation can be avoided, and an intermediate layer made of titanium carbide can be appropriately formed.

The titanium fuel cell separator manufacturing method according to the present invention includes a separator in which the adhesion between the base material and the carbon layer is greatly improved because the organic adhesive that bonds the base material and the carbon sheet contains carbon powder. Can be manufactured.
Further, in the method for producing a titanium fuel cell separator according to the present invention, the carbon powder contained in the organic adhesive is graphite powder, and the average particle diameter is 0.5 to 20 μm. Can be produced.
In addition, the method for manufacturing a titanium fuel cell separator according to the present invention performs the heat treatment in the heat treatment step in a non-oxidizing atmosphere having an oxygen partial pressure of 1.3 × 10 ⁻¹ Pa or less, so that the intermediate layer is appropriately formed. By being formed, it is possible to manufacture a separator that ensures the adhesion between the substrate and the carbon layer.
And, by improving the adhesion between the base material and the carbon layer, a carbon layer having excellent conductivity and corrosion resistance can be stably maintained on the base material. For a long period of time) and a separator excellent in corrosion resistance.

It is a flowchart which shows the manufacturing process of the titanium fuel cell separator which concerns on embodiment. It is a figure which shows order for the separator in the manufacturing process of the titanium fuel cell separator according to the embodiment. It is the schematic of the contact resistance measurement apparatus used in the contact resistance measurement in an Example, and adhesive evaluation.

  Hereinafter, embodiments for carrying out a method for producing a titanium fuel cell separator according to the present invention will be described in detail with reference to the drawings as appropriate.

≪Titanium fuel cell separator≫
First, a titanium fuel cell separator 10 (hereinafter, appropriately referred to as a separator) formed by the method for manufacturing a titanium fuel cell separator according to the embodiment will be described.
As shown in FIG. 2 (the figure after the heat treatment step S3), the separator 10 includes a base material 1 and a carbon layer 2 (a layer composed of a carbon sheet) formed on the surface (both sides or one side) of the base material 1. ) And an intermediate layer 3 formed at the interface between the substrate 1 and the carbon layer 2. In FIG. 2, the separator 10 in which the carbon layer 2 and the intermediate layer 3 are formed on both surfaces of the substrate 1 is shown, but the carbon layer 2 and the intermediate layer 3 are formed only on one surface of the substrate 1. May be.
Hereinafter, the base material 1, the carbon layer 2, and the intermediate layer 3 constituting the separator 10 will be described.

<Base material>
The substrate 1 of the separator 10 is made of pure titanium or a titanium alloy. Therefore, the base material 1 is lighter than the case where stainless steel or the like is used, and is excellent in corrosion resistance. Moreover, since pure titanium or a titanium alloy is excellent in strength and toughness, the strength and toughness of the substrate 1 can be secured.

  And the base material 1 is produced by a conventionally well-known method, for example, the method of melt | dissolving and casting pure titanium or a titanium alloy to make an ingot, hot rolling, and then cold rolling. The substrate 1 is preferably annealed, but the finished state is not limited, and any finished state such as “annealing + pickling finish”, “vacuum heat treatment finish”, “bright annealing finish”, etc. It does not matter.

  In addition, although the base material 1 is not limited to titanium of a specific composition, O: 1500 ppm or less (more preferably) from a viewpoint of the ease of cold rolling of titanium raw material, and subsequent press moldability ensuring. 1000 ppm or less), Fe: 1500 ppm or less (more preferably 1000 ppm or less), C: 800 ppm or less, N: 300 ppm or less, H: 130 ppm or less, with the balance being Ti and inevitable impurities. As the base material 1, for example, a JIS type 1 cold-rolled plate can be used.

  The plate thickness of the substrate 1 is preferably 0.05 to 1.0 mm. This is because if the plate thickness is less than 0.05 mm, the strength required for the substrate 1 cannot be ensured, while if it exceeds 1.0 mm, the workability decreases.

<Carbon layer>
The carbon layer 2 of the separator 10 is made of carbon having conductivity and corrosion resistance. And the carbon layer 2 is a layer formed by heat-processing, after adhere | attaching and pressing a carbon sheet on the base-material 1 surface.
The carbon sheet is not limited as long as it is a carbon-based sheet such as an expanded graphite sheet (a graphite sheet in which chemicals are inserted between flake graphite layers) or a carbon sheet, but is preferably an expanded graphite sheet. . By using the expanded graphite sheet, the carbon powder 2b contained in the organic adhesive 2a (used in the bonding step S1), which will be described later, can easily bite into the carbon sheet, and the contact area between the two increases, resulting in improved adhesion. Because it does. Further, since the expanded graphite sheet is oriented in parallel to the (002) plane (orientated in parallel to the carbon sheet surface), even if the pressure in the pressing process is low, low resistance (high conductivity) ) Can be secured.
Graphite is a hexagonal plate crystal composed of carbon in which a large number of graphene sheets having a hexagonal lattice structure and a sheet shape are stacked in layers.

  The carbon layer 2 is preferably coated on the entire surface of the substrate 1, but is not necessarily coated on the entire surface, and in order to ensure conductivity and corrosion resistance, 50% or more of the surface, Preferably, 70% or more may be covered.

  In addition, the average thickness of the carbon layer 2 on the surface of the substrate 1 affects the conductivity and the corrosion resistance. If the average thickness of the carbon layer 2 is less than 0.5 μm, sufficient conductivity and corrosion resistance cannot be obtained. On the other hand, if the average thickness of the carbon layer 2 exceeds 200 μm, the workability is lowered. Therefore, the thickness of the carbon layer 2 is preferably 0.5 to 200 μm or less.

  The average thickness of the carbon layer 2 can measure the cross section of the base material 1 and the carbon layer 2 using a scanning electron microscope (SEM) or the like. Here, the average thickness is, for example, the average thickness of the carbon layer 2 in the range of a width of 500 μm when a cross section is observed with an SEM.

<Intermediate layer>
At the interface between the base material 1 and the carbon layer 2, titanium carbide formed by a reaction between titanium of the base material 1 and carbon of a carbon sheet (and carbon powder 2 b contained in the organic adhesive 2 a described later). An intermediate layer 3 is formed. Since this titanium carbide has conductivity, the electrical resistance at the interface between the substrate 1 and the carbon layer 2 is reduced, and the conductivity of the separator 10 is improved. In addition, since titanium carbide is formed by the reaction of the base material 1 and the carbon sheet (and the carbon powder 2b), the adhesion between the base material 1 and the carbon layer 2 is improved.

The intermediate layer 3 is formed by a reaction between titanium of the base material 1 and carbon of the carbon sheet by heat treatment, and the interface between the base material 1 and the carbon layer 2 has an uneven shape. Therefore, compared with the case where the smooth intermediate layer 3 is formed by the vapor deposition method, the adhesion between the base material 1 and the carbon layer 2 becomes better.
The intermediate layer 3 is preferably formed at all interfaces between the base material 1 and the carbon layer 2, but is formed at 50% or more of the interfaces in order to ensure adhesion. Just do it.
And the formation state of this intermediate | middle layer 3 can be controlled by the heat processing conditions mentioned later.

The average thickness of the intermediate layer 3 is preferably 5 nm or more. This is because if the thickness is less than 5 nm, sufficient adhesion between the substrate 1 and the carbon layer 2 cannot be obtained.
The upper limit of the average thickness of the intermediate layer 3 is not particularly limited, but it may be 100 nm or less because there is no change in adhesion even if it exceeds 100 nm.

  The average thickness of the intermediate layer 3 can measure the cross section of the base material 1 and the carbon layer 2 using a transmission electron microscope (TEM) or the like. Here, the average thickness is, for example, the average thickness of the intermediate layer 3 in a width range of 500 nm when a cross section is observed with a TEM.

The separator 10 has been described above. However, when the organic adhesive 2 a used in the bonding step S <b> 1 described later is not thermally decomposed, it may remain between the base material 1 and the carbon layer 2.
The carbon powder 2b contained in the organic adhesive 2a is pressed against the carbon layer 2 or reacts with titanium to become a part of the intermediate layer 3.

Next, the organic adhesive 2a used in the manufacturing process (bonding process S1) of the titanium fuel cell separator 10 according to the present invention will be described.
≪Organic adhesive≫
Examples of the organic adhesive 2a used in the bonding step S1 include natural rubber, starch, acrylic resin, urethane resin, ether cellulose, epoxy resin, styrene-butadiene rubber, hot melt, and phenol resin. , Polystyrene resin, polyvinyl alcohol resin, polymethacrylate resin, and polyurethane resin adhesives. Among these, it is preferable to use ether type cellulose or polystyrene resin type that thermally decomposes in the heat treatment step S3 as the organic adhesive 2a. This is because when the organic adhesive 2a is thermally decomposed, the titanium of the substrate 1 and the carbon of the carbon sheet (and carbon powder 2b included in the organic adhesive 2a described later) react appropriately.

  The organic adhesive 2a contains carbon powder 2b. By containing the carbon powder 2b, first, in the press step S2, the carbon powder 2b bites into the base material 1 and the carbon sheet. In the heat treatment step S3, the carbon atoms of the carbon powder 2b and the carbon atoms of the carbon sheet are rearranged so that they are chemically and firmly bonded to each other. An intermediate layer 3 made of titanium carbide having an uneven structure is formed. As a result, the adhesion between the substrate 1 and the carbon sheet is improved.

  The carbon powder 2b is not particularly limited, and may be graphite powder (crystalline) or carbon powder (noncrystalline), but graphite powder is more preferable. When the carbon powder 2b is graphite powder, the carbon powder 2b is easily pulverized in the pressing step S2, and the pulverized carbon powder 2b is densely arranged at the interface between the substrate 1 and the carbon sheet. Therefore, the rearrangement of the carbon atoms of the carbon powder 2b and the carbon atoms of the carbon sheet in the heat treatment step S3 is appropriately performed, thereby further firmly joining.

  When the carbon powder 2b is graphite powder (crystalline), for example, flaky graphite, artificial graphite, earth graphite, or expanded graphite may be used. In addition, when the carbon powder 2b is graphite powder, the size of the carbon powder 2b is preferably an average particle size of 0.5 to 20 μm. If it is less than 0.5 μm, the performance (contact resistance, adhesion) is slightly inferior, and graphite powder of the size is not cheap and difficult to obtain. On the other hand, if it exceeds 20 μm, it will cause damage (break through etc.) of the carbon sheet.

  When the carbon powder 2b is carbon powder (non-crystalline), the carbon powder 2b is hardly pulverized in the pressing step S2. Therefore, in order to ensure improved adhesion, the carbon powder 2b, the carbon sheet, and the base It is necessary to increase the contact area with the material 1. Therefore, as the carbon powder, for example, a carbon black, acetylene black or the like having a small average particle size (average particle size of 0.01 to 0.2 μm) needs to be selected.

  The carbon powder 2b is preferably contained so as to be 1 to 50 wt% with respect to the total amount of the organic adhesive 2a and the carbon powder 2b. If it is less than 1 wt%, it is not possible to ensure an improvement in the adhesion between the substrate 1 and the carbon sheet, and if it exceeds 50 wt%, the viscosity increases and it becomes difficult to apply.

Next, a method for manufacturing the titanium fuel cell separator 10 according to the embodiment will be described.
≪Method for manufacturing titanium fuel cell separator≫
The manufacturing method of the titanium fuel cell separator 10 includes an adhesion step S1, a pressing step S2, and a heat treatment step S3.
Hereinafter, the manufacturing method of the titanium fuel cell separator 10 will be described step by step.

<Adhesion process>
The bonding step S1 is a step of bonding the carbon sheet to the surface of the base material 1 made of pure titanium or a titanium alloy using the organic adhesive 2a.

Adhesion process S1 may be performed by any of a continuous type (roll to roll) and a batch type (each sheet). For example, when performing continuously, the organic adhesive 2a containing the carbon powder 2b is coated on the surface (both sides or one side) of the belt-like substrate 1 (for example, gravure coater, reverse roll coater, roll knife coater, die coater). ) To apply continuously. Then, what is necessary is just to laminate | stack a carbon sheet continuously on the strip | belt-shaped base material 1 surface with which the organic adhesive 2a was apply | coated.
Here, when a carbon sheet is continuously pasted on the surface of the substrate 1, the carbon sheet may be a strip or a roll of a strip of carbon sheet (film) may be used. On the other hand, when performing by a batch type, what is necessary is just to use the carbon sheet cut | disconnected beforehand by the substantially same size (width, width | variety) as the base material 1. FIG.
In addition, it is preferable that a carbon sheet contains 97 mass% or more of carbon, and hydrogen etc. may be mixed unavoidable. And it is preferable that a carbon sheet is 10-200 micrometers thick.

In the bonding step S1, as described above, the organic adhesive 2a may be applied to the surface of the base 1 to attach the carbon sheet to the base 1, or the organic adhesive 2a may be applied to the carbon sheet. The carbon sheet may be attached to the substrate 1 by attaching.
As for the application of the organic adhesive 2a, first, an organic adhesive 2a that does not contain the carbon powder 2a is applied to the surface of the substrate 1 (or carbon sheet), and then the carbon powder 2b is applied. You may carry out by the process of.

  The application of the organic adhesive 2a in the bonding step S1 is not limited as long as it can be applied to the surface of the substrate 1 (or the carbon sheet), and may be performed using the various coaters described above or sprayed. Etc. may be performed.

<Pressing process>
The pressing step S2 is a step of pressing the substrate 1 to which the carbon sheet is bonded after the bonding step S1.

The press method in press process S2 is not specifically limited, What is necessary is just the method of applying a pressure to the base-material 1 surface, such as rolling.
And it is preferable that the pressure in press process S2 is 300-3000 MPa. If it is less than 300 MPa, the adhesion between the substrate 1 and the carbon sheet is not sufficient, and even if it exceeds 3000 MPa, the adhesion is only saturated.

  As long as the press in press process S2 is a press apparatus which can apply the pressure of 300-3000 MPa with respect to the base material 1, you may perform it by what kind of press apparatuses, such as a conventionally well-known rolling apparatus.

<Heat treatment process>
In the heat treatment step S3, the base material 1 to which the carbon sheet is pressure-bonded after the pressing step S2 is heat-treated to react the titanium of the base material 1 with the carbon of the carbon sheet (and the carbon powder 2b). This is a step of forming the intermediate layer 3 between the carbon layer 2.

The heat treatment in the heat treatment step S3 is preferably performed in a non-oxidizing atmosphere with an oxygen partial pressure of 1.3 × 10 ⁻¹ Pa or less. When the oxygen partial pressure exceeds 1.3 × 10 ⁻¹ Pa, the carbon of the carbon sheet reacts with oxygen in the atmosphere to become carbon dioxide (causes a combustion reaction), and titanium carbide (intermediate) This is because the amount of carbon forming the layer 3) is reduced.

  The heat treatment temperature in the heat treatment step S3 is preferably 300 to 850 ° C. If the temperature during the heat treatment is low, the reaction between the carbon of the carbon layer 2 and the titanium of the base material 1 hardly occurs, so that titanium carbide is not formed. On the other hand, if the temperature is high, the mechanical properties of the base material 1 are deteriorated. This is because there is a concern to do. A more preferable temperature range is 400 to 800 ° C, and further preferably 450 to 700 ° C.

  The heat treatment time is 2 to 10 minutes, and the time may be appropriately adjusted depending on the temperature, such as a long time treatment when the temperature is low and a short time treatment when the temperature is high.

  The heat treatment in the heat treatment step S3 may be performed in any heat treatment furnace such as an electric furnace or a gas furnace as long as the heat treatment can be performed at a heat treatment temperature of 300 to 850 ° C. and the atmosphere can be adjusted. .

  In addition, there is an example in which a titanium carbide layer (intermediate layer) and a carbon layer are formed on a titanium base material by a vapor deposition method. In this case, the titanium carbide layer is formed with a uniform thickness. As a result, a smooth interface is formed between the titanium carbide layer and the carbon layer, and peeling may occur at this portion. On the other hand, the titanium carbide layer of the present invention has an uneven shape at the interface with the carbon layer 2. It is considered that the titanium carbide layer is formed by the reaction between the carbon layer 2 and the titanium of the substrate 1, and that the interface becomes an uneven structure, thereby improving the adhesion between them.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the design can be appropriately changed without departing from the gist of the present invention described in the claims.
For example, you may perform the passive film removal process which removes the passive film of the base material 1 surface before adhesion process S1.

  Next, the titanium fuel cell separator manufacturing method according to the present invention will be specifically described by comparing an example satisfying the requirements of the present invention with a comparative example not satisfying the requirements of the present invention.

<Preparation of a specimen according to an example>
As a base material, JIS 1 type titanium base material (annealing pickling finish) was used. The chemical composition of the titanium base material is O: 450 ppm, Fe: 250 ppm, N: 40 ppm, the balance is Ti and inevitable impurities, and the plate thickness of the titanium base material is 0.5 mm.

An expanded graphite sheet (thickness: 100 μm) was adhered to both surfaces of the substrate using an ether-based cellulose adhesive containing a predetermined amount of the carbon powder shown in Table 1. Thereafter, cold rolling is performed at 1500 MPa or 700 MPa, and heat treatment (750 ° C., 5 minutes) is performed in a non-oxidizing atmosphere (1.3 × 10 ⁻³ Pa), whereby the specimens according to the examples (Nos. 1 to 3). ) Was produced.

<Preparation of a specimen according to a comparative example>
An expanded graphite sheet using an ether-based cellulose adhesive containing a predetermined amount of the carbon powder shown in Table 1 or an ether-based cellulose adhesive containing no carbon powder on both surfaces of a base material similar to the test body according to the example. (Thickness 100 μm) was adhered. Thereafter, cold rolling is performed at 1500 MPa or 700 MPa, and heat treatment (750 ° C., 5 minutes) is performed in a non-oxidizing atmosphere (1.3 × 10 ⁻³ Pa), whereby the specimens according to the comparative examples (No. 4, 5) ) Was produced.

  The test specimens thus produced were subjected to contact resistance measurement and adhesion evaluation by the following methods.

[Contact resistance measurement]
The contact resistance was measured using the contact resistance measurement device 30 shown in FIG. Specifically, both surfaces of the test body 31 are sandwiched between two carbon cloths 32 and 32, and the outside is sandwiched between two copper electrodes 33 and 33 having a contact area of 1 cm ² and pressurized with a load of 98 N (10 kgf). A 7.4 mA current was passed using a direct current power supply 34, and the voltage applied between the carbon cloths 32 and 32 was measured with a voltmeter 35 to determine the contact resistance.
When the contact resistance (shown as the initial contact resistance in Table 1) is 10 mΩ · cm ² or less, the conductivity is good, and when it exceeds 10 mΩ · cm ² , the conductivity is poor.

[Adhesion evaluation]
Adhesion evaluation was performed using the contact resistance measuring apparatus 30 shown in FIG. A state in which both sides of the test body 31 are sandwiched between two carbon cloths 32 and 32 and the outside is sandwiched between copper electrodes 33 and 33 having a contact area of 1 cm ² and pressurized to a load of 98 N (10 kgf). The test body 31 was pulled out in the in-plane direction while holding (pull-out test).
After the pull-out test, the non-friction surface and the friction surface were observed at a magnification of 100 times with SEM / EDX, and when the acceleration voltage was 15 kV and titanium (Ti) and carbon (C) were quantitatively analyzed, When the amount of carbon (atomic%) is 100% and the amount of carbon on the friction surface is 80% or more of the amount of carbon on the non-friction surface, ○ (very good), the amount of carbon on the friction surface Is △ (good) when the amount of carbon on the non-friction surface is 50% or more and less than 80%, and × (defect) when the amount of carbon on the friction surface is less than 50% of carbon on the non-friction surface It was judged.

  Type of carbon sheet of each test specimen, type of carbon powder in adhesive, carbon powder content (= carbon powder mass / (carbon powder mass + organic adhesive mass) × 100), rolling surface pressure, presence / absence of heat treatment Table 1 shows contact resistance and adhesion.

The test specimens (No. 1 and No. 2) containing carbon powder (graphite powder) in the organic adhesive and heat-treated were the result that the adhesion was very good and the result that the electrical conductivity was good. became.
And the test body (No. 3) which made the organic adhesive contain carbon powder (acetylene black) and heat-treated was the test body No. 3 in terms of adhesion. Although it was inferior compared with 1 and 2, it was a result that it was favorable and it became a result that electroconductivity was favorable.
On the other hand, the test body (No. 4) in which the organic adhesive did not contain carbon powder resulted in poor adhesion.
Moreover, while the test body (No. 5) which did not heat-process was a result that adhesiveness was unsatisfactory, it also became a result unsatisfactory also about electroconductivity.

  From the results in Table 1, a titanium fuel cell separator manufactured by adhering a base material and a carbon sheet using an organic adhesive containing carbon powder, and applying a press and heat treatment, It has been found that the adhesiveness and the conductivity are excellent.

1 Base Material 2 Carbon Layer 2a Organic Adhesive (Adhesive)
2b Carbon powder 3 Intermediate layer 10 Titanium fuel cell separator (separator)
30 Contact Resistance Measuring Device 31 Specimen 32 Carbon Cloth 33 Copper Electrode 34 DC Current Power Supply 35 Voltmeter S1 Adhesion Process S2 Press Process S3 Heat Treatment Process

Claims (3)

A method of manufacturing a titanium fuel cell separator in which a carbon layer is provided on a substrate surface made of pure titanium or a titanium alloy,
An adhesion step of adhering a carbon sheet to be the carbon layer to the substrate surface using an organic adhesive, a pressing step of pressing the substrate after the adhesion step, and heat-treating the substrate after the pressing step A heat treatment step,
The method for producing a titanium fuel cell separator, wherein the organic adhesive contains carbon powder.   The said carbon powder is graphite powder, and an average particle diameter is 0.5-20 micrometers, The manufacturing method of the titanium fuel cell separator of Claim 1 characterized by the above-mentioned. The method for producing a titanium fuel cell separator according to claim 1 or 2, wherein the heat treatment in the heat treatment step is performed in a non-oxidizing atmosphere having an oxygen partial pressure of 1.3 x 10 ^-1 Pa or less. .

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