Titanium or titanium alloy material for fuel cell separator having high contact conductivity with carbon and high durability, fuel cell separator including the same, and manufacturing method therefor

Patent metadata

Field	Value
Publication number	US-10074857-B2
Application number	US-201314415964-A
Country	US
Kind code	B2
Filing date	Jul 30, 2013
Priority date	Jul 31, 2012
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

A titanium or titanium alloy material for a separator of a polymer electrolyte fuel cell having high contact conductivity with carbon and high durability, and including an oxide film formed on a titanium or titanium alloy substrate by a stabilization treatment performed after a passivation treatment, and one or more kinds of conductive materials selected from carbide, nitride, carbonitride, and boride of tantalum, titanium, vanadium, zirconium, and chromium, the conductive materials being dispersed in the oxide film and having a major axis diameter of from 1 nm to 100 nm. A contact resistance value with a carbon paper is 20 mΩ·cm 2 or less at a surface pressure of 10 kgf/cm 2 before and after an accelerated deterioration test in which the titanium or titanium alloy material is immersed in a sulfuric acid aqueous solution having an adjusted pH of 4 at 80° C. for four days.

First claim

The invention claimed is:

1. A titanium or titanium alloy material for a fuel cell separator, the titanium or titanium alloy material comprising:
an oxide film formed on a titanium or titanium alloy substrate; and
one or more kinds of conductive materials selected from carbide, nitride, carbonitride, and boride of tantalum, titanium, vanadium, zirconium, and chromium, the conductive materials being dispersed in the oxide film and having a major axis diameter from 1 nm to 100 nm,
wherein a contact resistance value with a carbon paper is 20 mΩ·cm 2 or less at a surface pressure of 10 kgf/cm 2 before and after an accelerated deterioration test in which the titanium or titanium alloy material is immersed in a sulfuric acid aqueous solution having an adjusted pH of 4 at 80° C. for four days,
wherein carbon is present on a superficial layer of the oxide film,
wherein one of condition (a) or (b) is satisfied: (a) a fraction of carbon atoms whose nearest neighboring atom is a double-bond oxygen atom is 2 atomic % or more, (b) a fraction of carbon atoms whose nearest neighboring atom is an oxygen atom of a hydroxyl group is 10 atomic % or more, and
wherein condition (c) is satisfied: (c) a fraction of carbon atoms whose nearest neighboring atom is a hydrogen atom of an alkyl group is 40 atomic % or less.

2. The titanium or titanium alloy material for a fuel cell separator according to claim 1 ,
wherein 1 atomic % or more nitrogen atoms whose nearest neighboring atom is a hydrogen atom are present on the superficial layer of the oxide film.

3. The titanium or titanium alloy material for a fuel cell separator according to claim 2 ,
wherein 1 atomic % or more calcium is present on the superficial layer of the oxide film.

4. The titanium or titanium alloy material for a fuel cell separator according to claim 3 ,
wherein 1 atomic % or more trivalent chromium is present on the superficial layer of the oxide film as oxide or oxyhydroxide.

5. The titanium or titanium alloy material for a fuel cell separator according to claim 2 ,
wherein 1 atomic % or more trivalent chromium is present on the superficial layer of the oxide film as oxide or oxyhydroxide.

6. The titanium or titanium alloy material for a fuel cell separator according to claim 1 ,
wherein the oxide film is formed by a passivation treatment, followed by a stabilization treatment.

7. The titanium or titanium alloy material for a fuel cell separator according to claim 6 ,
wherein the passivation treatment is performed after anode electrolysis is performed on the titanium or titanium alloy substrate in a neutral aqueous solution containing 0.01 mass % or more and 5 mass % or less fluoride ions, or an alkaline aqueous solution having a pH of 12 or more, with a current density from 1 A/m 2 to 20 A/m 2 .

8. The titanium or titanium alloy material for a fuel cell separator according to claim 6 ,
wherein the stabilization treatment is treatment in which the titanium or titanium alloy material is immersed in an aqueous solution at 60° C. or more to which one or more selected from 1 mass ppm or more rice flour, wheat flour, potato starch, corn flour, soy flour, amine-based compounds, aminocarboxylic-acid-based compounds, phospholipid, a commercially available acidic corrosion inhibitor, polyethylene glycol, and starch are added.

9. A fuel cell separator comprising:
the titanium or titanium alloy material for a fuel cell separator according to claim 1 ,
wherein carbon or a carbon-containing conductive film is further added to a surface of the titanium or titanium alloy material.

10. A manufacturing method for the titanium or titanium alloy material for a fuel cell separator of claim 1 , the manufacturing method comprising:
adding one or more kinds of conductive materials selected from carbide, nitride, carbonitride, and boride of tantalum, titanium, vanadium, zirconium, and chromium to a surface of a titanium or titanium alloy substrate, and then performing passivation treatment in which the substrate is immersed in an aqueous solution obtained by mixing one or more selected from 5 mass % or more nitric acid, 1 mass % or more chromic anhydride, and 5 mass % or more sulfuric acid; and then
performing stabilization treatment in which the substrate is immersed in an aqueous solution at 60° C. or more to which one or more selected from 1 mass ppm or more rice flour, wheat flour, potato starch, corn flour, soy flour, amine-based compounds, aminocarboxylic-acid-based compounds, phospholipid, a commercially available acidic corrosion inhibitor, polyethylene glycol, and starch are added,
wherein the aqueous solution deactivates active oxygen.

11. The manufacturing method for a titanium or titanium alloy material for a fuel cell separator according to claim 10 ,
wherein, prior to the passivation treatment, passivation pre-treatment is performed in which anode electrolysis is performed on the titanium or titanium alloy substrate, to which the conductive materials have been added, in a neutral aqueous solution containing 0.01 mass % or more and 5 mass % or less fluoride ions, or an alkaline aqueous solution having a pH of 12 or more, with a current density from 1 A/m 2 to 20 A/m 2 .

12. The manufacturing method for a titanium or titanium alloy material for a fuel cell separator according to claim 10 , the manufacturing method further comprising:
performing treatment in which carbon or a carbon-containing conductive film is further added to a surface of the titanium or titanium alloy material on which the stabilization treatment has been performed.

13. The manufacturing method for a titanium or titanium alloy material for a fuel cell separator according to claim 11 , the manufacturing method further comprising:
performing treatment in which carbon or a carbon-containing conductive film is further added to a surface of the titanium or titanium alloy material on which the stabilization treatment has been performed.

14. The titanium or titanium alloy material for a fuel cell separator according to claim 6 ,
wherein the passivation treatment is treatment in which the titanium or titanium alloy substrate is immersed in an aqueous solution at 50° C. or more, obtained by mixing one or more selected from 5 mass % or more nitric acid, 1 mass % or more chromic anhydride, and 5 mass % or more sulfuric acid.

15. The titanium or titanium alloy material for a fuel cell separator according to claim 1 ,
wherein the stabilization treatment is a treatment to deactivate active oxygen.

Assignees

• Nippon Steel & Sumitomo Metal Corp

Inventors

• Kihira Hiroshi
• Yosida Yuuichi
• Kagawa Taku
• Nishimoto Takumi
• Tanaka Koki
• Kimura Masao
• Tokuno Kiyonori
• Takahashi Kazuhiro
• Domoto Takashi

Classifications

• Y02E60/50

  Fuel cells · CPC title

• H01M8/0228 Primary

  in the form of layered or coated products · CPC title

• C23C14/34

  Sputtering · CPC title

• H01M8/0208

  Alloys · CPC title

• C23C28/3455

  with a refractory ceramic layer, e.g. refractory metal oxide, ZrO2, rare earth oxides or a thermal barrier system comprising at least one refractory oxide layer · CPC title