Abstract: A copper-coated steel wire includes a core wire made of a steel and a coating layer made of copper or a copper alloy which covers an outer peripheral surface of the core wire. The coating layer includes an intermediate layer which is disposed in a region including the interface with the core wire and has a higher zinc concentration than a remaining region of the coating layer.

Abstract: A copper-coated steel wire includes a core wire made of a steel and a coating layer that covers the outer peripheral surface of the core wire and is made of copper or a copper alloy. In a cross section perpendicular to the longitudinal direction of the core wire, the ten-point average roughness Rzjis of the outer peripheral surface of the core wire is 50% or more and 250% or less of the thickness of the coating layer.

Abstract: A copper-coated steel wire includes a core wire made of a stainless steel, and a coating layer made of copper or a copper alloy and covering an outer peripheral surface of the core wire. In a cross section perpendicular to a longitudinal direction of the core wire, the outer peripheral surface of the core wire has a value of an arithmetic mean roughness Ra of not less than 25% and not more than 90% of a thickness of the coating layer.

Abstract: A copper-coated steel wire includes a core wire made of a steel, and a coating layer made of copper or a copper alloy and covering an outer peripheral surface of the core wire. In a cross section perpendicular to a longitudinal direction of the core wire, the core wire includes a plurality of oxide regions composed of an oxide of an element contained in the steel constituting the core wire, the oxide regions including the outer peripheral surface of the core wire and being disposed apart from each other in a circumferential direction of the core wire.

Abstract: A copper-coated steel wire includes a core wire made of a steel and a coating layer made of copper or a copper alloy which covers an outer peripheral surface of the core wire. The coating layer includes an intermediate layer which is disposed in a region including the interface with the core wire and has a higher zinc concentration than a remaining region of the coating layer.

Abstract: A method is provided for producing a functional membrane having a structure in which pores of a porous substrate are filled with a functional polymer, the method having improved productivity and improving the stability of performance. The method for producing a functional membrane formed by filling pores of a porous substrate with a functional polymer involves carrying out a treatment of the porous substrate with a suspension of a surfactant before filling the pores of the porous substrate with a solution of the functional polymer or a solution of a precursor thereof, carrying out a drying step, and then filling with the solution of the functional polymer or the solution of the precursor thereof.

Abstract: To provide a membrane electrode assembly suitable for a fuel cell or an electrochemical device, and a direct methanol fuel cell employing the membrane electrode assembly. A membrane electrode assembly comprising an electrolyte membrane formed from a porous substrate having the interior of pores filled with a polymer electrolyte, and an electrode disposed on opposite faces of the electrolyte membrane and having a catalyst layer formed from a catalyst and a polymer electrolyte, the polymer electrolyte content in the catalyst layer being higher in a face where the catalyst layer is in contact with the electrolyte membrane than in other regions of the catalyst layer; and a direct methanol fuel cell employing the membrane electrode assembly.