A lamellar structure graphite foil is used as a material for a separator for a fuel cell, and a hydrophobic layer is formed by impregnation on flow-field channels of the graphite foil. Such a separator is manufactured by forming the flow field channel by etching the graphite foil formed with the mask pattern thereon and forming a hydrophobic layer by impregnation. According to such a separator, performance of a fuel cell stack is enhanced and the manufacturing process of a separator is simplified.

Fuel cell alloy bipolar plates. The alloys may be used as a coating or bulk material. The alloys and metallic glasses may be particularly suitable for proton-exchange membrane fuel cells because of they may exhibit reduced weights and/or better corrosion resistance. The alloys may include any of the following Al.sub.xCu.sub.yTi.sub.z, Al.sub.xFe.sub.yNi.sub.z, Al.sub.xMn.sub.yNi.sub.z, Al.sub.xNi.sub.yTi.sub.z, Cu.sub.xFe.sub.yTi.sub.z, Cu.sub.xNi.sub.yTi.sub.z, Al.sub.xFe.sub.ySi.sub.z, Al.sub.xMn.sub.ySi.sub.z, Al.sub.xNi.sub.ySi.sub.z, Ni.sub.xSi.sub.yTi.sub.z, and C.sub.xFe.sub.ySi.sub.z. The alloys or metallic glass may be doped with various dopants to improve glass forming ability, mechanical strength, ductility, electrical or thermal conductivities, hydrophobicity, and/or corrosion resistance.

Fuel cell alloy bipolar plates. The alloys may be used as a coating or bulk material. The alloys and metallic glasses may be particularly suitable for proton-exchange membrane fuel cells because of they may exhibit reduced weights and/or better corrosion resistance. The alloys may include any of the following Al.sub.xCu.sub.yTi.sub.z, Al.sub.xFe.sub.yNi.sub.z, Al.sub.xMn.sub.yNi.sub.z, Al.sub.xNi.sub.yTi.sub.z, Cu.sub.xFe.sub.yTi.sub.z, Cu.sub.xNi.sub.yTi.sub.z, Al.sub.xFe.sub.ySi.sub.z, Al.sub.xMn.sub.ySi.sub.z, Al.sub.xNi.sub.ySi.sub.z, Ni.sub.xSi.sub.yTi.sub.z, and C.sub.xFe.sub.ySi.sub.z. The alloys or metallic glass may be doped with various dopants to improve glass forming ability, mechanical strength, ductility, electrical or thermal conductivities, hydrophobicity, and/or corrosion resistance.

There is provided a steel for solid oxide fuel cells which contains more than 0 and not more than 0.05 mass % of C, 0.05 mass % or less of N, 0.01 mass % or less of O, 0.2 mass % or less of Al, 0.15 mass % or less of Si, 0.1 to 1.0 mass % of Mn, 20.0 to 25.0 mass % of Cr, more than 0 mass % and not more than 1.0 mass % of Ni, 0.02 to 0.12 mass % of La, 0.1 to 0.5 mass % of Zr, 0.15 to 0.5 mass % of La+Zr, and Fe and impurities as a remainder. The following relational formula is satisfied, and an Fe and Zr-containing intermetallic compound viewed in a ferrite matrix is 1.1 % or less in terms of a visual field area ratio
5(7C+6N)/(7−4(7C+6N))≤Zr≤41(7C+6N)/(7+66(7C+6N)).

There is provided a steel for solid oxide fuel cells which contains more than 0 and not more than 0.05 mass % of C, 0.05 mass % or less of N, 0.01 mass % or less of O, 0.2 mass % or less of Al, 0.15 mass % or less of Si, 0.1 to 1.0 mass % of Mn, 20.0 to 25.0 mass % of Cr, more than 0 mass % and not more than 1.0 mass % of Ni, 0.02 to 0.12 mass % of La, 0.1 to 0.5 mass % of Zr, 0.15 to 0.5 mass % of La+Zr, and Fe and impurities as a remainder. The following relational formula is satisfied, and an Fe and Zr-containing intermetallic compound viewed in a ferrite matrix is 1.1 % or less in terms of a visual field area ratio
5(7C+6N)/(7−4(7C+6N))≤Zr≤41(7C+6N)/(7+66(7C+6N)).

Stainless steel with improved hydrophilicity and contact resistance for a Polymer Electrolyte Membrane Fuel Cell (PEMFC) separator, and a method of manufacturing the stainless steel Stainless steel are disclosed. Stainless steel for a Polymer Electrolyte Membrane Fuel Cell (PEMFC) separator according to an embodiment of the present disclosure may include: by weight percent, 0 to 0.02% of C (excluding 0), 0 to 0.02% of N (excluding 0), 0 to 0.25% of Si (excluding 0), 0 to 0.2% of Mn (excluding 0), 0 to 0.04% of P (excluding 0), 0 to 0.02% of S (excluding 0), 20 to 34% of Cr, 0 to 0.6% of V (excluding 0), 0 to 0.5% of Ti (excluding 0), 0 to 0.5% of Nb (excluding 0), and the remainder comprising iron (Fe) and other unavoidable impurities, wherein a plurality of patterns may be formed on a surface of the stainless steel in a direction that is inclined with respect to a rolling direction, and the plurality of patterns are arranged repeatedly in the rolling direction.

Stainless steel with improved hydrophilicity and contact resistance for a Polymer Electrolyte Membrane Fuel Cell (PEMFC) separator, and a method of manufacturing the stainless steel Stainless steel are disclosed. Stainless steel for a Polymer Electrolyte Membrane Fuel Cell (PEMFC) separator according to an embodiment of the present disclosure may include: by weight percent, 0 to 0.02% of C (excluding 0), 0 to 0.02% of N (excluding 0), 0 to 0.25% of Si (excluding 0), 0 to 0.2% of Mn (excluding 0), 0 to 0.04% of P (excluding 0), 0 to 0.02% of S (excluding 0), 20 to 34% of Cr, 0 to 0.6% of V (excluding 0), 0 to 0.5% of Ti (excluding 0), 0 to 0.5% of Nb (excluding 0), and the remainder comprising iron (Fe) and other unavoidable impurities, wherein a plurality of patterns may be formed on a surface of the stainless steel in a direction that is inclined with respect to a rolling direction, and the plurality of patterns are arranged repeatedly in the rolling direction.

Layers for a bipolar plates are disclosed, as well as bipolar plates including the layers and fuel cells and/or electrolyzers including the bipolar plates. The layer may include a homogeneous or heterogeneous solid metallic solution or compound which either contains a first chemical element from the group of the noble metals in the form of iridium; or contains a first chemical element from the group of the noble metals in the form of iridium and a second chemical element from the group of the noble metals in the form of ruthenium. The layer may also include at least one further nonmetallic chemical element from the group consisting of nitrogen, carbon, boron, fluorine, and hydrogen.

Layers for a bipolar plates are disclosed, as well as bipolar plates including the layers and fuel cells and/or electrolyzers including the bipolar plates. The layer may include a homogeneous or heterogeneous solid metallic solution or compound which either contains a first chemical element from the group of the noble metals in the form of iridium; or contains a first chemical element from the group of the noble metals in the form of iridium and a second chemical element from the group of the noble metals in the form of ruthenium. The layer may also include at least one further nonmetallic chemical element from the group consisting of nitrogen, carbon, boron, fluorine, and hydrogen.

A stainless steel material including a base material made of ferritic stainless steel, a Cr oxide layer formed on a surface of the base material, and a spinel oxide layer formed on a surface of the Cr oxide layer, wherein a chemical composition of the base material satisfies [16.0≤Cr+3×Mo−2.5×B−17×C−3−Si≤35.0], a thickness of the Cr oxide layer (T.sub.Cr) and a thickness of the spinel oxide layer (T.sub.S) satisfy [0.55≤T.sub.Cr/T.sub.S≤6.7], the base material contains precipitate including one or more kinds selected from a M.sub.23C.sub.6, a M.sub.2B, a complex precipitate in which M.sub.2B acts as a precipitation nucleus, and M.sub.23C.sub.6 precipitates on a surface of the M.sub.2B, and a complex precipitate in which NbC acts as a precipitation nucleus, and M.sub.23C.sub.6 precipitates on a surface of the NbC, and a part of the precipitate protrude from the surface of the Cr oxide layer.