Titanium material or titanium alloy material having surface electrical conductivity, and fuel cell separator and fuel cell using the same
The composition ratio of a titanium hydride [I Ti—H /(I Ti +I Ti—H )]×100 found from the maximum intensity of metal titanium (I Ti ) and the maximum intensity of the titanium hydride (I Ti—H ) 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° 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.
1. A titanium material or a titanium alloy material, wherein
the composition ratio of a titanium hydride [I Ti—H /(I Ti +I Ti—H )]×100 found from the maximum intensity of metal titanium (I Ti ) and the maximum intensity of the titanium hydride (I Ti—H ) 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° is 55% or more,
a titanium oxide film is formed on an outermost surface of the titanium or the titanium alloy,
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, and
each of the amounts of increase in contact resistance from before to after deterioration test 1 and deterioration test 2 below is 10 mΩcm 2 or less,
deterioration test 1: immersion for 4 days in a sulfuric acid solution at 80° C. and pH 3 containing 2 ppm F ions,
deterioration test 2: application of an electric potential of 1.0 V (vs. SHE) for 24 hours in a sulfuric acid solution at 80° C. and pH 3.
2. A fuel cell separator comprising the titanium material or the titanium alloy material according to claim 1 .
3. A polymer electrolyte fuel cell comprising the fuel cell separator according to claim 2 .