Nippon Steel Sumitomo Metal Corporation

Nippon Steel Corporation

Atsuhiko Kuroda

Kazuhiro Takahashi

Masanari Kimoto

Kiyonori Tokuno

Junko Imamura

Taku Kagawa

Kouichi Takeuchi

Hidenori Takebe

Kentaroh Yoshida

Jyunko Imamura

A titanium plate includes a chemical composition of industrial pure titanium, in which an arithmetic mean roughness Ra of a surface is 0.05 &#x3bc;m or more and 0.40 &#x3bc;m or less, the surface has titanium carbide regarding which a ratio between a total sum of integrated intensities Ic derived from the titanium carbide and a total sum of integrated intensities Im of all diffraction peaks derived from the titanium carbide and titanium obtained from X-ray diffractometry ((Ic/Im)&#xd7;100) is 0.8% or more and 5.0% or less, a number density of asperities on the surface is 30 to 100 pieces/mm, and an average spacing of the asperities is 20 &#x3bc;m or less.

Titanium plate

In a titanium material or a titanium alloy material, in an oxide film formed on a surface of a titanium or a titanium alloy, the composition ratio of TiO (I/(I+I)&#xd7;100 found from the maximum intensity of the X-ray diffraction peaks of TiO (I) and the maximum intensity of the X-ray diffraction peaks of metal titanium (I) in X-ray diffraction measured at an incident angle to the surface of 0.3&#xb0; is 0.5% or more. A titanium material or a titanium alloy material, and a fuel cell separator and a polymer electrolyte fuel cell having good contact-to-carbon electrical conductivity and good durability can be provided.

Titanium material or titanium alloy material having surface electrical conductivity and method for producing the same, and fuel cell separator and fuel cell using the same

The composition ratio of a titanium hydride [I/(I+I)]&#xd7;100 found from the maximum intensity of metal titanium (I) and the maximum intensity of the titanium hydride (I) of the X-ray diffraction peaks measured at a surface of a titanium or a titanium alloy at an incident angle to the surface of 0.3&#xb0; is 55% or more, a titanium oxide film is formed on an outermost surface of the titanium or the titanium alloy, and C is at 10 atomic % or less, N is at 1 atomic % or less, and B is at 1 atomic % or less in a position where the surface has been subjected to sputtering of 5 nm with argon. The titanium oxide film is formed by performing stabilization treatment after performing passivation treatment in prescribed aqueous solutions, and has a thickness of 3 to 10 nm.

Titanium material or titanium alloy material having surface electrical conductivity, and fuel cell separator and fuel cell using the same

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Atsuhiko Kuroda