Improved contact between interconnect and oxygen electrode material is achieved through a contact point between an electrode or a contact layer and a coated ferritic stainless steel interconnect, where the coating on the metallic interconnect comprises Cu.

Improved contact between interconnect and oxygen electrode material is achieved through a contact point between an electrode or a contact layer and a coated ferritic stainless steel interconnect, where the coating on the metallic interconnect comprises Cu.

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.

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.

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.

Disclosed is a method for manufacturing a stainless steel for a polymer electrolyte membrane fuel cell separator, and more particularly, a method for manufacturing a stainless steel for a polymer electrolyte membrane fuel cell separator capable of obtaining low contact resistance and high corrosion resistance by effectively removing a non-conductive coating and forming a new coating. According to an embodiment, the disclosed method for manufacturing a stainless steel for a polymer electrolyte membrane fuel cell separator includes performing alternating current electrolysis by immersing, in a sulfuric acid solution, a stainless steel having a passivation coating formed on a surface thereof by cold rolling and bright annealing, wherein the alternating current electrolysis is performed by applying a current density of 10 to 30 A/dm.sup.2.

Disclosed is a method for manufacturing a stainless steel for a polymer electrolyte membrane fuel cell separator, and more particularly, a method for manufacturing a stainless steel for a polymer electrolyte membrane fuel cell separator capable of obtaining low contact resistance and high corrosion resistance by effectively removing a non-conductive coating and forming a new coating. According to an embodiment, the disclosed method for manufacturing a stainless steel for a polymer electrolyte membrane fuel cell separator includes performing alternating current electrolysis by immersing, in a sulfuric acid solution, a stainless steel having a passivation coating formed on a surface thereof by cold rolling and bright annealing, wherein the alternating current electrolysis is performed by applying a current density of 10 to 30 A/dm.sup.2.

A cell stack device includes a cell stack and an end current collector. The cell stack includes a plurality of cells arrayed therein. The end current collector is located in an end portion of the cell stack in an array direction of the plurality of cells. The end current collector includes a surface exposed to an oxidizing atmosphere covered with a covering material including manganese and a surface exposed to a reducing atmosphere covered with a film different from the covering material.

A cell stack device includes a cell stack and an end current collector. The cell stack includes a plurality of cells arrayed therein. The end current collector is located in an end portion of the cell stack in an array direction of the plurality of cells. The end current collector includes a surface exposed to an oxidizing atmosphere covered with a covering material including manganese and a surface exposed to a reducing atmosphere covered with a film different from the covering material.