| 摘要 |
PURPOSE: A stainless steel for the separator of a polymer electrolyte membrane fuel cell and a manufacturing method thereof are provided to secure the low interfacial contact resistance, thereby obtaining the steel suitable for the separator. CONSTITUTION: A stainless steel for the separator of a polymer electrolyte membrane fuel cell comprises 0 to 0.02 wt% of C, 0 to 0.02 wt% of N, 0 to 0.4 wt% of Si, 0 to 0.2 wt% of Mn, 0 to 0.04 wt% of P, 0 to 0.02 wt% of S, 25 to 34 wt% of Cr, 0 to below 2.5 wt% of Mo, 0 to 1 wt% of Cu, 0 to below 0.2 wt% of Ni, 0 to 0.5 wt% of Ti, 0 to 0.5 wt% of Nb, Fe, and other inevitable impurities. The hydroxide/oxide ratio of a passive film on the surface of the steel is over 1, and the interfacial contact resistance of the film is below 20 mΩcm^2 (150 N/cm^2). The steel further includes one or two elements selected from a group of composites added with one or a mixture of over 0.2 to 1 of V wt% and 0 to 4 wt% of W. A Cr-hydroxide/oxide ratio inside the film is over 2. [Reference numerals] (AA) Intensity; (BB) Hydroxide; (CC) Oxide; (DD) Invention example 4; (EE) Invention example 3; (FF) Invention example 2; (GG) Invention example 1; (HH) Comparative example 2; (II) Comparative example 1; (JJ) Comparative example 3; (KK) Binding energy (eV) |
