Patent ID: 8137866

Claim:
A separator for a fuel cell comprising a titanium material, the titanium material comprising: a titanium alloy substrate comprising at least one noble metal element selected from the group consisting of platinum group elements, Au and Ag; and a layer of a mixture formed on a surface of the titanium alloy substrate, the mixture comprising a noble metal element precipitated from the titanium alloy substrate and a titanium oxide formed from the titanium alloy substrate, and said layer having an average thickness of up to 200 nm; wherein: the mixture layer on the surface and the titanium alloy substrate have a conductivity in terms of contact resistance of up to 10 mΩ·cm 2 ; and contact resistance is determined by: placing a carbon cloth having an average thickness of 0.3 mm on opposite surfaces of a sample of the titanium alloy substrate having the mixture layer formed thereon: sandwiching the sample of the titanium alloy material with a pair of copper electrodes via the carbon cloth, the copper electrodes each having a contact area with the titanium alloy material of 1 cm 2 ; and measuring a voltage drop between the carbon cloths by using a four terminal ohmmeter while pressing the copper electrodes against the sample of the titanium alloy material at a surface pressure of 5 kg/cm 2 by using a hydraulic press and applying an electric current of 7.4 mA between the copper electrodes.