JP2008251297A - Separator material for fuel cell and separator for fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separator material for a fuel cell having high corrosion resistance, high conductivity, and high mechanical strength in a separator formed by forming a noble metal film on a titanium base material. <P>SOLUTION: The separator material for the fuel cell has one or more noble metal conductive films selected from the group comprising Ru, Rh, Pd, Ir, Os, and Pt on the titanium base material, and has an Au conductive film on the conductive film, and the mechanical strength of the titanium base material is increased by forming one or more kinds of quenched-hardened layers selected from the group comprising a titanium oxide, a titanium nitride and a titanium carbide including a noble metal oxide on the titanium base material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a material used for a metal separator for a solid polymer electrolyte fuel cell.

  A polymer electrolyte fuel cell separator is a member that constitutes a fuel cell stack in which a plurality of single cells are stacked, and requires sufficient gas impermeability and electrical conductivity for electrical connection between cells. is there. Furthermore, high corrosion resistance is also required for an acidic atmosphere. Conventionally, carbon materials or metal materials have been used for such fuel cell separators. Since carbon materials have lower strength than metal materials, it is difficult to make the thickness of carbon materials the same level as metal materials, and the processing costs are high, so metal materials have been widely studied in recent years. .

A problem when a metal material is used as a metal separator for a fuel cell is compatibility between corrosion resistance and conductivity. For example, in the case of stainless steel, it is generally said that the corrosion resistance is good, but there is a problem that the corrosion resistance is not sufficient for the acidic atmosphere in the fuel cell stack and the components of stainless steel are eluted. On the other hand, in the case of titanium having higher corrosion resistance than stainless steel, a very strong oxide film having a thickness of several nanometers is present on the surface, so that there is a problem that contact resistance is increased.
As a technique for achieving both corrosion resistance and conductivity in the characteristics of a metal separator for a fuel cell, techniques (Patent Documents 1, 2, and 3) of precious metal plating on a base material such as stainless steel are disclosed.

JP 2001-006713 A JP 2004-185998 A JP 2006-278172 A

However, a separator using titanium as a metal material and having at least one kind of noble metal selected from the group consisting of Ru, Rh, Pd, Ir, Os, and Pt on the surface of the titanium material has the following problems. Have
1) Among the noble metals, a chemically stable and resource-rich material is Au. However, when the metal material is a titanium material, it is difficult to directly form Au on the titanium surface.
2) On the other hand, when Ru, Rh, Pd, Ir, Os, and Pt, which are noble metals other than Au, are present in the outermost layer of the metal separator, the noble metal changes into a noble metal oxide in the environment of the fuel cell. There was a problem that the contact resistance of the high.
3) Titanium is an expensive metal compared to stainless steel, etc., so the titanium substrate for separators should be as thin as possible in terms of cost. However, if the thickness of the titanium substrate is reduced, the material strength There was a problem.

  In view of the above problems, an object of the present invention is to provide a material for a fuel cell separator that has corrosion resistance and conductivity and is excellent in strength in a separator in which a noble metal is formed on a titanium substrate.

As a result of earnestly examining the technology having both corrosion resistance, conductivity and strength, the present inventor has obtained a titanium material having excellent corrosion resistance as a base material of the separator, in order to obtain conductivity, Ru, Rh, Pd, Ir, Os and Conductive film made of at least one kind of noble metal selected from the group consisting of Pt, Au conductive film to supplement the oxidation resistance of Ru, Rh, Pd, Ir, Os and Pt, and thickness of the metal separator Is thin, it is sufficient to have one or more hardened layers selected from the group consisting of titanium oxide, titanium nitride and titanium carbide containing noble metal oxide in order to give sufficient strength to the separator. It has been found that it exhibits excellent corrosion resistance, conductivity and strength.

That is, the present invention is as follows.
(1) A noble metal conductive film made of at least one selected from the group consisting of Ru, Rh, Pd, Ir, Os and Pt is made of a titanium base material, and has a conductive film of Au on the conductive film. A fuel cell separator material.

(2) From Ru, Rh, Pd, Ir, Os and Pt to a titanium substrate having at least one kind of hardened layer selected from the group consisting of an oxide layer, a nitride layer and a carbonized layer on a titanium material. A fuel cell separator material comprising a noble metal conductive film made of at least one selected from the group consisting of a conductive film of Au on the conductive film.

(3) A titanium base material having at least one hardened layer selected from the group consisting of titanium oxide containing noble metal oxide, titanium nitride and titanium carbide on a titanium material. The fuel cell separator material according to (2) above.

(4) Titanium nitride in which the thickness of the titanium oxide layer containing a noble metal oxide in which the oxygen concentration is in the range of 10 at% or more is 30 nm to 200 nm and the nitrogen concentration is in the range of 10 at% or more. (3) above, wherein the thickness of the titanium carbide layer having a layer thickness of 30 nm or more and a carbon concentration of 10 at% or more is at least one selected from the group consisting of 30 nm or more. The separator material for fuel cells as described.

(5) The thickness of the noble metal conductive film made of at least one selected from the group consisting of Ru, Rh, Pd, Ir, Os and Pt described in (1) to (4) above is 1 nm or more. A fuel cell separator material.

(6) A fuel cell separator material, wherein the Au conductive film according to any one of (1) to (5) has a thickness of 1 nm or more.

(7) A separator material for a fuel cell, wherein the titanium material according to the above (1) to (6) is industrial pure titanium.

(8) A separator material for a fuel cell, wherein the thickness of the titanium material according to (1) to (7) is 30 μm or more.

(9) The fuel cell according to any one of (1) and (5) to (8), wherein the noble metal conductive film and the Au conductive film are formed on a pressed titanium material for forming a reactive gas flow path. Separator.

(10) In the above (1) and (5) to (8), the titanium material on which the noble metal conductive film is formed is pressed for forming the reaction gas flow path, and then the Au conductive film is formed. The fuel cell separator as described.

(11) The fuel cell according to any one of (1) and (5) to (8), wherein the noble metal conductive film and the Au conductive film are formed on a titanium material, and then pressed to form a reaction gas flow path. Separator for use.

(12) A hardened layer is formed on a pressed titanium material to form a reactive gas flow path, and then the noble metal conductive film and Au conductive film are formed, as described in (2) to (8) above Fuel cell separator.

(13) The titanium material on which the hardened layer is formed is pressed for forming a reactive gas flow path, and then the noble metal conductive film and the Au conductive film are formed. Fuel cell separator.

(14) The titanium material on which the hardened layer and the noble metal conductive film are formed is pressed for forming a reaction gas flow path, and then the Au conductive film is formed, as described in (2) to (8) above Fuel cell separator.

(15) The fuel according to any one of (2) to (8), wherein the noble metal conductive film and the Au conductive film are formed on the titanium base material on which the hardened layer is formed, and then pressed to form a reaction gas channel. Battery separator.

(16) A fuel cell stack using the fuel cell separator material and the fuel cell separator according to (1) to (15) above.

In the present invention, when expressing titanium as a material used for a base material or titanium before forming a hardened layer, it is referred to as “titanium material”, and titanium before forming a conductive film, that is, when there is no hardened layer. When there is a hardened layer, the titanium material is expressed as a “titanium substrate” by combining the hardened layer and the titanium material.

  It is possible to provide a material for a fuel cell separator that is excellent in strength while having corrosion resistance and conductivity in a separator in which a noble metal is formed on a titanium base material.

  The present invention pays attention to the conductivity of a noble metal, and uses titanium having a high contact resistance as a separator material substrate and forms the noble metal as a conductive film in common with the conventional invention. However, in the present invention, there is a problem of adhesion between the noble metal and the titanium base material, and there is a problem of oxidation in the battery environment. Therefore, in terms of finding a multilayer structure of Au and another noble metal, Different. Furthermore, it is also a feature of the present invention that the base titanium material has a multilayer structure with a hardened layer selected from the group consisting of titanium oxide containing noble metal oxide, titanium nitride and titanium carbide.

That is, the present invention is as follows.
1) A conductive film of Au prevents oxidation of a conductive film made of at least one kind of noble metal selected from the group consisting of Ru, Rh, Pd, Ir, Os, and Pt in an oxidizing atmosphere.
2) Since the hardened layer is harder than titanium, the hardened layer serves to supplement the strength of the titanium plate.

The specific reason for limitation will be described below.
(1) Kind and thickness of substrate (or material used for substrate) As a separator material for a fuel cell, both corrosion resistance and conductivity are required. Therefore, the base material is required to have corrosion resistance, and a titanium material is used for the base material in the present invention.
The type of titanium material is industrial pure titanium. Since the titanium material is pressed for forming the reaction gas flow path, JIS type 1 having good workability is desirable among pure titanium.
The thickness of the titanium material used for the substrate is 30 μm or more. In order to produce a titanium material having a thickness of less than 30 μm, the processing cost becomes high. There is no technical limitation on the upper limit of the thickness of the titanium material. However, the titanium material is an expensive metal, and it is preferable that the titanium material be thin, and it is desirable that the thickness be 200 μm or less in consideration of cost.

(2) Type and thickness of conductive film The present invention is to form a conductive film having adhesion to a titanium base material and a conductive film having oxidation resistance on a titanium base material.
First, the conductive film having adhesiveness with the titanium substrate (hereinafter referred to as a noble metal conductive film) is at least one selected from the group consisting of Ru, Rh, Pd, Ir, Os, and Pt. A noble metal conductive film made of Among these, Pd is contained in three relatively noble metals (Au, Pt, Pd) having a relatively large amount of resources, and is promising as a separator material because of its lowest price among the three noble metals.

The lower limit of the thickness necessary for obtaining sufficient adhesion between the titanium base material and the upper Au layer is 1 nm. When the thickness of the conductive film is less than 1 nm, a portion that is not formed may be generated, and it may be impossible to form a conductive film of Au with good adhesion. On the other hand, the upper limit of the thickness is not technically limited, but it is only necessary to ensure the adhesion between the base material and the Au conductive film, and the precious metal is expensive and desirably thin. Considering the cost, it is considered to be 100 nm or less.
A sputtering method is effective as a film forming method. The sputtering method can form an adhesive conductive film of the present invention even if oxygen, nitrogen and carbon are present on the titanium surface.

On the other hand, the conductive film having oxidation resistance is an Au conductive film. Since Au is chemically stable, the titanium base material becomes a separator having excellent corrosion resistance and conductivity when used as the outermost layer of the metal separator. If an Au film is formed directly on a titanium substrate without a conductive film, a film with good adhesion cannot be formed unless a natural oxide film on the titanium surface is removed to some extent.
The lower limit of the thickness of the Au conductive film for obtaining sufficient oxidation resistance as a separator is 1 nm. If the thickness is less than 1 nm, the noble metal conductive film formed under Au may be exposed. In this case, the noble metal is oxidized and a noble metal oxide is formed, so that the contact resistance is increased. On the other hand, there is no technical limitation on the upper limit of the thickness. However, Au is also expensive, and considering the cost, it is desirable to set it to 100 nm or less.
The sputtering method used for forming the conductive film is effective as the film forming method. By using the same sputtering method, the noble metal can be continuously formed by the same film forming apparatus.

(3) Type and thickness of hardened layer Titanium as a material used for the base material is an expensive metal compared to stainless steel or the like, so that it is desired to reduce the thickness of the base material from the viewpoint of cost.
However, when the thickness of the titanium substrate is reduced, the strength as a separator material may be insufficient. Then, this invention exists in providing a hardened layer in order to obtain sufficient intensity | strength as a base material of a separator. That is, forming a hardened layer on the titanium material, forming a hardened layer by changing a part of the titanium material, and forming a hardened layer combining the above. The hardened layer is a layer composed of at least one selected from the group consisting of an oxide layer, a nitride layer, and a carbide layer, specifically, a titanium oxide, a titanium nitride, and a titanium carbide containing a noble metal oxide. A layer composed of one or more types selected from the group consisting of More specifically, a titanium oxide layer containing a noble metal oxide having an oxygen concentration detected when analyzed by XPS (analysis area 800 μmΦ) in a range of 10 at% or more, and a nitrogen concentration in a range of 10 at% or more. A titanium nitride layer is a layer composed of one or more selected from a titanium carbide layer having a carbon concentration in the range of 10 at% or more. Since these hardened layers are harder than titanium as a base material, they contribute to improving the strength of the separator.

  The lower limit of the thickness of the titanium oxide layer containing the noble metal oxide is 30 nm on one side, preferably 100 nm. When the thickness of the titanium oxide layer containing the noble metal oxide is less than 30 nm, the strength of the titanium base material cannot be supplemented when the thickness of the titanium base material is thin. On the other hand, the upper limit of the thickness of the titanium oxide layer containing the noble metal oxide is 200 nm. When the thickness of the titanium oxide layer containing the noble metal oxide exceeds 200 nm, the adhesion between the titanium base material and the conductive film may deteriorate. The titanium oxide layer may be formed in advance from an oxide layer present on the surface of the titanium base material. When the thickness of the titanium oxide layer is less than 30 nm, it is necessary to thicken the oxide layer on the titanium surface before forming the conductive film. Examples of the method include heat treatment and anodic oxidation with the titanium substrate placed in an oxidizing environment. In the present invention, the titanium oxide layer may be formed by a method other than heat treatment or anodic oxidation. In addition, the presence of the noble metal oxide contributes to an improvement in adhesion between the titanium base material and the conductive film.

  The lower limit of the titanium nitride layer or the titanium carbide layer is 30 nm on one side, preferably 100 nm. When the thickness of the titanium nitride layer or the titanium carbide layer is less than 30 nm, the strength of the titanium material cannot be supplemented when the thickness of the titanium substrate is thin. On the other hand, although the titanium nitride layer or the titanium carbide layer is hard and improves the strength of the titanium material, the press workability is poor, so if the thickness of the titanium material is thin, the titanium material will crack in the press work after forming the hardened layer. There is a case. Therefore, the upper limit of the hardened layer varies depending on the thickness of the titanium base material, but is desirably 5000 nm or less, preferably 1000 nm or less.

The titanium nitride layer or the titanium carbide layer may be formed from a titanium nitride layer or a titanium carbide layer prepared as a sputtering target using a sputtering method, or reactive sputtering may be used to form argon gas on the titanium surface. It may be formed by irradiation with nitrogen gas or acetylene gas. Alternatively, it may be formed by high-temperature heat treatment in a nitrogen gas atmosphere. In the present invention, the titanium nitride layer or the titanium carbide layer may be formed by a method other than sputtering or heat treatment.

(4) Manufacturing method of separator The manufacturing process of the separator which formed the reactive gas flow path in this invention becomes the following seven types.
1) A method of forming a conductive film and a conductive film of Au on a titanium base material that has been press-processed to form a reactive gas flow path. 2) A titanium base material having a conductive film formed thereon is used to form a reactive gas flow path. 3) Forming a noble metal conductive film and an Au conductive film on a titanium substrate, and then press forming to form a reaction gas flow path Method 4) Pressing the titanium substrate, forming a cured layer after the pressing, and then forming a noble metal conductive film and Au conductive film in this order 5) Forming the cured layer on the titanium substrate, Method of press-working titanium substrate, then forming conductive film and Au conductive film in this order 6) Forming hardened layer on titanium substrate, then forming noble metal conductive film and pressing on titanium substrate Method of processing and then forming Au conductive film 7) The method 4), in which a hardened layer is formed on a tan base, and then a film is formed in the order of a noble metal conductive film and an Au conductive film, and the titanium base is pressed, requires a hardened layer. Among the methods of) to 7), the press working is performed before the cured layer is formed, so that the processing is easy. Therefore, it is an effective method because the strength of the separator can be improved.

The titanium material used in the present invention is an industrial pure titanium material (JIS class 1). The thickness of the titanium material is 30 to 100 μm described in Table 1. There is a titanium oxide of about 60 nm in advance on the surface of the titanium material. Before forming the conductive film, the titanium material surface is subjected to a treatment as shown in Table 1 to form a titanium oxide film which is one of the hardened layers. Titanium materials with different thicknesses were prepared.
The titanium nitride layer or the titanium carbide layer, which is a kind of the hardened layer, was formed by sputtering on a titanium material in which the titanium material surface was previously mechanically polished to a titanium material oxide thickness of about 3 nm.
The conductive film made of Pd was formed on the surface of the hardened layer using a sputtering method.
An Au conductive film was also formed on the conductive film by sputtering.
FIG. 1 shows the structure of a titanium material in which a hardened layer, a conductive film, and a conductive film of Au are formed on the titanium material.

The conditions for forming the hardened layer (titanium nitride layer, titanium carbide layer), conductive film, and conductive film of Au are as follows.
Formation conditions of hardened layer (titanium nitride layer, titanium carbide layer) Formation method 1: Sputtering method Sputtering apparatus: manufactured by ULVAC, Inc. Sputtering condition: output DC 50 W, argon pressure 0.2 Pa
Formation Method 2: Heat Treatment Method Titanium nitride was formed by heat treatment of the titanium material at 850 ° C. in a nitrogen atmosphere.

Formation method of conductive film Formation method: Sputtering method Sputtering device: manufactured by ULVAC, Inc. Sputtering condition: Output DC 50 W Argon pressure 0.2 Pa
Formation conditions of Au conductive film Formation method: Sputtering method Sputtering apparatus: manufactured by ULVAC, Inc. Sputtering condition: output DC 50 W, argon pressure 0.2 Pa

  Titanium base material on which hardened layer, conductive film and Au conductive film are formed, the composition and thickness of hardened layer, conductive film and Au conductive film are confirmed, and contact resistance before and after adhesion and corrosion resistance tests The shape maintenance was evaluated by the following method.

Confirmation of composition and thickness of hardened layer, noble metal conductive film and Au conductive film Confirmation of composition and thickness of hardened layer, noble metal conductive film and Au conductive film on the surface of titanium material is deep from the surface of Au conductive film. X-ray photoelectron spectroscopic analysis (XPS, ULVAC-PHI Co., Ltd. model 5600MC, sputtering rate: 10 nm / min in terms of SiO 2), and X-ray photoelectron spectroscopic analysis software (manufactured by ULVAC-PHI, Inc., Multipak Ver.) 7.0.1), and was performed by peak separation.
The titanium oxide layer, titanium nitride layer, and titanium carbide layer containing the noble metal oxide as the composition of the hardened layer were obtained from oxygen, nitrogen, and carbon in the range of 10 at% or more detected by XPS analysis. Titanium oxide contains noble metal oxide, but titanium oxide and noble metal are separated by peak separation using X-ray photoelectron spectroscopic analysis diffraction software (manufactured by ULVAC-PHI, Inc., Multipak Ver. 7.0.1). Oxide oxide can be separated.
The noble metal conductive film and the Au conductive film were obtained from a noble metal component in a range of 5 at% or more detected by XPS analysis.

Adhesion Adhesion is determined by scoring a grid pattern at 1 mm intervals on the surface of the conductive film of each test piece, and applying a tape peeling test (adhesive tape is applied to the Au conductive film. A method of investigating the adhesion between the conductive film and the oxidation-resistant conductive film by peeling off strongly. Further, each test piece was arbitrarily bent by 180 ° to return to the original state, and a tape peeling test of the bent portion was performed.

Contact resistance The contact resistance was measured by applying a load to the entire surface of the sample. As shown in FIG. 2, a 40 × 50 mm sample and carbon paper are laminated, and the sample and carbon paper are plated from the top and bottom with a 1.0 μm Ni undercoat on a copper plate (10 mmt) of the same size, and 0.5 μm thereon. The sample was rubbed with an Au-plated material, a load of 10 kg / cm ² was applied to the sample, and the electric resistance when a current of 100 mA / cm ² was passed was measured by the 4-terminal method.

Corrosion resistance The corrosion resistance test was performed by immersing each test piece having a size of 40 x 50 mm in a sulfuric acid aqueous solution (pH = 1.8, liquid amount 350 cc) at a bath temperature of 90C for 168 hours (one week). The contact resistance before and after the corrosion resistance test of the test piece was evaluated.

Shape maintenance The shape maintenance was evaluated by the following method. The upper and lower sides of the titanium material press-molded into the shape shown in FIG. 3 are sandwiched with carbon paper, and a load of 10 kg / cm ² is applied to the sample once. Thereafter, the load applied to the titanium material was released, and the change in the uneven shape of the pressed titanium material before and after the load was applied was observed with a microscope. The case where there was no change in the uneven shape was marked with ◯, and the case where even a part of the shape was deformed was marked with ×.

The results are shown in Table 1 below.

Invention Example No. Reference numeral 1 denotes a separator material comprising a titanium substrate having a thickness of 100 μm, a titanium oxide having a thickness of 3 nm, a Pd conductive film having a thickness of 10 nm, and an Au having a thickness of 10 nm as a hardened layer. The evaluation of adhesion, contact resistance, and shape maintenance was good.
Invention Example No. 2 is a separator material comprising a titanium substrate having a thickness of 100 μm, a titanium oxide having a thickness of 60 nm, a Pd conductive film having a thickness of 10 nm, and an Au having a thickness of 10 nm as a hardened layer. The evaluation of adhesion, contact resistance, and shape maintenance was good.

Invention Example No. 3 is a separator material composed of a titanium substrate having a thickness of 30 μm, a thickness of 3 nm of titanium oxide + 50 nm of titanium nitride, a thickness of Pd conductive film of 10 nm, and a thickness of Au of 10 nm as a hardened layer. The evaluation of adhesion, contact resistance and shape maintenance was good.
Invention Example No. 4 is a separator material comprising a titanium substrate having a thickness of 30 μm, a thickness of 3 nm of titanium oxide + 50 nm of titanium carbide, a thickness of Pd conductive film of 10 nm, and a thickness of Au of 10 nm as a hardened layer. The evaluation of adhesion, contact resistance, and shape maintenance was good.
Invention Example No. 5 and 6 are separator materials comprising a titanium substrate having a thickness of 30 μm, a titanium oxide having a thickness of 30 nm or 200 nm as a hardened layer, a Pd conductive film having a thickness of 10 nm, and an Au having a thickness of 10 nm. The evaluation of adhesion, contact resistance, and shape maintenance was good.

Invention Example No. 7-No. 9 is a separator material comprising a titanium substrate having a thickness of 30 μm, a thickness of 3 nm of titanium oxide as a hardened layer + 30, 300, 1000 nm of titanium nitride, a thickness of Pd conductive film of 10 nm, and a thickness of Au of 10 nm. . The evaluation of adhesion, contact resistance, and shape maintenance was good.
Invention Example No. 10-No. 11 is a separator material comprising a titanium substrate having a thickness of 100 μm, a titanium oxide having a thickness of 60 nm, a Pd conductive film having a thickness of 1, 100 nm, and an Au having a thickness of 10 nm as a hardened layer. The evaluation of adhesion, contact resistance, and shape maintenance was good.
Invention Example No. 12-No. Reference numeral 13 denotes a separator material comprising a titanium substrate having a thickness of 100 μm, a titanium oxide having a thickness of 60 nm, a Pd conductive film having a thickness of 10 nm, and an Au having a thickness of 1, 100 nm as a hardened layer. The evaluation of adhesion, contact resistance, hydrogen absorption, and shape maintenance was good.

Comparative Example No. 14 is a separator material in which a titanium substrate having a thickness of 3 nm as a hardened layer, a conductive film, and a conductive film of Au is not formed on a titanium substrate having a thickness of 100 μm. Since there is no conductive film or Au conductive film, the contact resistance before and after the corrosion resistance test is high.
Comparative Example No. 15 is a separator material in which a titanium substrate having a thickness of 3 μm, a Pd conductive film having a thickness of 10 nm, and an Au conductive film is not provided on a titanium substrate having a thickness of 100 μm. Since there is no Au conductive film, the contact resistance before and after the corrosion resistance test is high.

Comparative Example No. Reference numeral 16 denotes a separator material having a titanium substrate with a thickness of 60 nm as a hardened layer and no conductive film and no conductive film of Au on a titanium substrate having a thickness of 100 μm. Since there is no conductive film or Au conductive film, the contact resistance before and after the corrosion resistance test is high.
Comparative Example No. 17 is a separator material in which a titanium plate having a thickness of 60 μm, a Pd conductive film having a thickness of 10 nm, and a Au conductive film is not provided on a titanium plate having a thickness of 100 μm. Since there was no Au conductive film, the contact resistance after the corrosion test was greatly increased.
Comparative Example No. 18 is a separator material having a titanium substrate having a thickness of 30 μm, a titanium oxide thickness of 3 nm + a titanium nitride thickness of 50 nm as a hardened layer, and no conductive film and Au conductive film. Since there was no conductive film or Au conductive film, the contact resistance after the corrosion resistance test was greatly increased.

Comparative Example No. No. 19 is a separator material having a titanium substrate with a thickness of 30 μm, a thickness of 3 nm of titanium oxide + 50 nm of titanium carbide as a hardened layer, and no conductive film and no conductive film of Au. Since there was no conductive film or Au conductive film, the contact resistance after the corrosion resistance test was greatly increased.
Comparative Example No. No. 20 is a separator material having a titanium substrate with a thickness of 30 μm, a titanium oxide thickness of 3 nm + a titanium nitride thickness of 50 nm, a Pd conductive film thickness of 10 nm, and no Au conductive film as a hardened layer. Since there was no Au conductive film, the contact resistance after the corrosion test was greatly increased.

Comparative Example No. No. 21 is a separator material in which a titanium plate having a thickness of 3 nm + a titanium carbide thickness of 50 nm, a Pd conductive film thickness of 10 nm, and a Au conductive film is not provided on a titanium plate having a thickness of 100 μm. Since there was no Au conductive film, the contact resistance after the corrosion test was greatly increased.
Comparative Example No. 22 is a separator material comprising a titanium substrate having a thickness of 30 μm, a titanium oxide having a thickness of 10 nm, a Pd conductive film having a thickness of 10 nm, and an Au having a thickness of 10 nm as a hardened layer. Since the thickness of the titanium substrate was thin and the thickness of the hardened layer made of titanium oxide was thin, the shape maintainability was poor.
Comparative Example No. Reference numeral 23 denotes a separator material comprising a titanium substrate having a thickness of 30 μm, a titanium oxide having a thickness of 250 nm, a Pd conductive film having a thickness of 10 nm, and an Au having a thickness of 10 nm as a hardened layer. Since the thickness of the titanium substrate was thin and the thickness of the hardened layer made of titanium oxide was thick, a part of the adhesion between the titanium base material and the conductive film was poor.

Comparative Example No. 24 is a separator material comprising a titanium substrate having a thickness of 30 μm, a titanium oxide thickness of 3 nm + a titanium nitride thickness of 15 nm, a Pd conductive film thickness of 10 nm, and an Au thickness of 10 nm as a hardened layer. Since the thickness of the titanium substrate was thin and the thickness of the hardened layer made of titanium oxide and titanium nitride was thin, the shape maintaining property was poor.
Comparative Example No. 25 is a separator material composed of a titanium substrate having a thickness of 30 μm, a titanium oxide thickness of 3 nm + titanium nitride thickness of 6000 nm, a Pd conductive film thickness of 10 nm, and an Au thickness of 10 nm as a hardened layer. Since the thickness of the titanium substrate was thin and the thickness of the hardened layer made of titanium oxide and titanium nitride was thick, the shape maintaining property was poor.

Comparative Example No. 26 is a separator material comprising a titanium substrate having a thickness of 100 μm, a titanium oxide having a thickness of 60 nm, a Pd conductive film having a thickness of 0.5 nm, and an Au having a thickness of 10 nm as a hardened layer. Since the Pd conductive film was thin, the adhesion between the titanium substrate and the conductive film was partially poor.
Comparative Example No. 27 is a separator material comprising a titanium substrate having a thickness of 100 μm, a titanium oxide thickness of 60 nm as a hardened layer, a Pd conductive film thickness of 10 nm, and an oxidation resistant conductive film thickness of 0.5 nm. . Since the thickness of Au was thin, the contact resistance after the corrosion resistance test was greatly increased.

It is the figure which showed the structure of the material for fuel cell separators of this invention. It is a figure which shows the contact resistance measuring method of the titanium material which formed the electroconductive film which applies a load to the sample whole surface. It is a figure which shows the uneven | corrugated shape of the sample for investigating shape maintenance property.

Claims (16)

  At least one type of noble metal conductive film selected from the group consisting of Ru, Rh, Pd, Ir, Os, and Pt is formed on a titanium substrate, and a conductive film of Au is formed on the conductive film. A separator material for a fuel cell, comprising:   From a group consisting of Ru, Rh, Pd, Ir, Os and Pt to a titanium substrate having at least one kind of hardened layer selected from the group consisting of an oxide layer, a nitride layer and a carbonized layer on a titanium material A fuel cell separator material comprising: a noble metal conductive film made of at least one selected type, and a conductive film of Au on the conductive film.   The titanium substrate having at least one kind of hardened layer selected from the group consisting of titanium oxide containing noble metal oxide, titanium nitride and titanium carbide on a titanium material. The separator material for fuel cells according to 2.   The thickness of the titanium nitride layer having a thickness of 30 nm to 200 nm and a nitrogen concentration of 10 at% or more in a titanium oxide layer containing a noble metal oxide having a oxygen concentration in the range of 10 at% or more in the hardened layer in the titanium substrate 4. The fuel cell according to claim 3, wherein the thickness of the titanium carbide layer having a thickness of 30 nm or more and a carbon concentration in the range of 10 at% or more is at least one selected from the group consisting of 30 nm or more. Separator material.   A fuel characterized in that the thickness of at least one kind of noble metal conductive film selected from the group consisting of Ru, Rh, Pd, Ir, Os and Pt according to claim 1 to 4 is 1 nm or more. Battery separator material.   A fuel cell separator material, wherein the Au conductive film according to any one of claims 1 to 5 has a thickness of 1 nm or more.   7. The fuel cell separator material, wherein the titanium substrate according to claim 1 is industrial pure titanium.   8. A fuel cell separator material, wherein the titanium substrate according to claim 1 has a thickness of 30 [mu] m or more.   9. The fuel cell separator according to claim 1, wherein a noble metal conductive film and an Au conductive film are formed on a pressed titanium substrate for forming a reaction gas flow path.   9. The fuel cell according to claim 1, wherein the titanium base material on which the noble metal conductive film is formed is pressed to form a reaction gas flow path, and then an Au conductive film is formed. Separator for use. 9. The fuel cell separator according to claim 1, wherein a noble metal conductive film and an Au conductive film are formed on a titanium base material, and then pressed to form a reaction gas flow path.   9. The fuel cell according to claim 2, wherein a hardened layer is formed on a pressed titanium substrate for forming a reaction gas flow path, and then a noble metal conductive film and an Au conductive film are formed. Separator.   9. The fuel cell according to claim 2, wherein the titanium base material on which the hardened layer is formed is pressed to form a reaction gas flow path, and then a noble metal conductive film and an Au conductive film are formed. Separator.   9. The fuel cell according to claim 2, wherein the titanium base material on which the hardened layer and the noble metal conductive film are formed is pressed to form a reaction gas flow path, and then an Au conductive film is formed. Separator.   9. The separator for a fuel cell according to claim 2, wherein a noble metal conductive film and an Au conductive film are formed on the titanium base material on which the hardened layer is formed, and then pressed to form a reaction gas flow path. A fuel cell stack using the fuel cell separator material and the fuel cell separator according to claim 1.

Images