Solid polymer type fuel cell separator and method of production of same
The present invention provides a separator for a solid polymer type fuel cell superior in low contact resistance of the fuel cell separator surface with carbon paper and flatness and a method of production of the same, that is, a separator for a solid polymer type fuel cell comprising a substrate of stainless steel or titanium or a titanium alloy having a surface layer part on which conductive compound particles are fixed, wherein said conductive compound particles are comprised of one or more types of metal borides, metal carbides, and metal nitrides with an average particle size of 0.01 to 20 μm, said conductive compound particles are present in a region from said substrate surface to a depth of 10 μm, and a distribution of concentration of the metal element forming the conductive compound in said region satisfies relations between a concentration C of the metal element forming the conductive compound and a depth x from the substrate surface shown by equation <1> (C=A·exp(−x/t)+B) and equation <2> (10≦A≦90, −4.0≦B≦1.0, 0.5≦t≦4.0).
1. A separator for a solid polymer type fuel cell comprising a substrate of stainless steel or titanium or a titanium alloy having a surface layer part on which conductive compound particles are fixed, said separator for a solid polymer type fuel cell characterized in that said conductive compound particles are comprised of one or more types of metal borides, metal carbides, and metal nitrides with an average particle size of 0.01 to 20 μm, said conductive compound particles are present in a region from said substrate surface to a depth of 10 μm, and a distribution of concentration of the metal element forming the conductive compound at the substrate surface in the depth direction is, at a depth of 0.1 μm from the substrate surface, 4.0 mass % to 89 mass %, at a depth of 0.2 μm, 2.7 mass % to 87 mass %, at a depth of 0.4 μm, 0.4 mass % to 83 mass %, at a depth of 0.5 μm, not more than 81 mass %, at a depth of 1 μm, not more than 72 mass %, at a depth of 2 μm, not more than 56 mass %, at a depth of 3 μm, not more than 44 mass %, at a depth of 4 μm, not more than 35 mass %, at a depth of 5 μm, not more than 27 mass %, at a depth of 6 μM, not more than 22 mass %, at a depth of 7 μm, not more than 17 mass %, at a depth of 8 μm, not more than 14 mass %, and, at a depth of 9 μm, not more than 11 mass %.
2. A separator for a solid polymer type fuel cell as set forth in claim 1 , characterized in that the metal element forming said conductive compound is one or more of Cr, V, W, Ta, La, Mo, and Nb.