The present invention provides a surface treatment method that improves antimicrobial activity of copper or a copper alloy and enhances immediate effects of antimicrobial actions on the surface of the copper or the copper alloy. A surface treatment method for copper or a copper alloy according to the present invention comprises preparing a reducing agent solution containing a biological reducing substance, and treating the surface of the copper or the copper alloy with the reducing agent solution. The present invention also provides a surface treatment liquid for sterilizing copper or a copper alloy, in which the surface treatment liquid contains a biological reducing substance. The present invention also provides a sterilization method that comprises bringing copper or a copper alloy treated by the surface treatment method into contact with a surface of an object to sterilize the surface of the object.

The present invention provides a surface treatment method that improves antimicrobial activity of copper or a copper alloy and enhances immediate effects of antimicrobial actions on the surface of the copper or the copper alloy. A surface treatment method for copper or a copper alloy according to the present invention comprises preparing a reducing agent solution containing a biological reducing substance, and treating the surface of the copper or the copper alloy with the reducing agent solution. The present invention also provides a surface treatment liquid for sterilizing copper or a copper alloy, in which the surface treatment liquid contains a biological reducing substance. The present invention also provides a sterilization method that comprises bringing copper or a copper alloy treated by the surface treatment method into contact with a surface of an object to sterilize the surface of the object.

A pure copper powder with a Si coating formed thereon, wherein a Si adhesion amount is 5 wtppm or more and 200 wtppm or less, a C adhesion amount is 15 wtppm or more, and a weight ratio C/Si is 3 or less. An object of the present invention is to provide a pure copper powder with a Si coating formed thereon and a production method thereof, as well as an additive manufactured object using such pure copper powder capable of suppressing the partial sintering of the pure copper powder caused by the preheating thereof in additive manufacturing based on the electron beam (EB) method, and suppressing the loss of the degree of vacuum caused by carbon (C) during the molding process.

The present invention provides a surface treatment method that improves antimicrobial activity of copper or a copper alloy and enhances immediate effects of antimicrobial actions on the surface of the copper or the copper alloy. A surface treatment method for copper or a copper alloy according to the present invention comprises preparing a reducing agent solution containing a biological reducing substance, and treating the surface of the copper or the copper alloy with the reducing agent solution. The present invention also provides a surface treatment liquid for sterilizing copper or a copper alloy, in which the surface treatment liquid contains a biological reducing substance. The present invention also provides a sterilization method that comprises bringing copper or a copper alloy treated by the surface treatment method into contact with a surface of an object to sterilize the surface of the object.

The present invention provides a surface treatment method that improves antimicrobial activity of copper or a copper alloy and enhances immediate effects of antimicrobial actions on the surface of the copper or the copper alloy. A surface treatment method for copper or a copper alloy according to the present invention comprises preparing a reducing agent solution containing a biological reducing substance, and treating the surface of the copper or the copper alloy with the reducing agent solution. The present invention also provides a surface treatment liquid for sterilizing copper or a copper alloy, in which the surface treatment liquid contains a biological reducing substance. The present invention also provides a sterilization method that comprises bringing copper or a copper alloy treated by the surface treatment method into contact with a surface of an object to sterilize the surface of the object.

A wire rod of a Cu—Zn—Si based alloy obtained by up-drawing continuous casting is provided; the amount of Cu is within a range of 75.0 mass% or more and 76.9 mass% or less, the amount of Si is within a range of 2.6 mass% or more and 3.1 mass% or less, the amount of Zr is within a range of 0.003 mass% or more and 0.20 mass% or less, the amount of P is within a range of 0.02 mass% or more and 0.15 mass% or less, the balance is composed of Zn and inevitable impurities, and the number density of a Zr—P compound containing Zr and P is within a range of 1500 pieces/mm.sup.2 or more and 7000 pieces/mm.sup.2 or less.

This free-cutting copper alloy contains Cu: 58.5 to 63.5%, Si: more than 0.4% and 1.0% or less, Pb: 0.003 to 0.25%, and P: 0.005 to 0.19%, with the remainder being Zn and inevitable impurities, a total amount of Fe, Mn, Co and Cr is less than 0.40%, a total amount of Sn and Al is less than 0.40%, a relationship of 56.3≤f1=[Cu]−4.7×[Si]+0.5×[Pb]−0.5×[P]≤59.3 is satisfied, constituent phases of a metal structure have relationships of 20≤(α)≤75, 25≤(β)≤80, 0≤(γ)<2, 20≤(γ).sup.1/2×3+(β)×(−0.5×([Si]).sup.2+1.5×[Si])≤78, and 33≤(γ).sup.1/2×3+(β)×(−0.5×([Si]).sup.2+1.5×[Si])+([Pb]).sup.1/2×33+([P]).sup.1/2×14, and a compound including P is present in β phase.

Copper alloys exhibiting enhanced oxidation resistance are provided by adding an amount of sulfur that is effective to enhance oxidative resistance. Such sulfur addition can be achieved by combining elemental forms of copper and sulfur and heating the mixture to form a molten alloy, or by forming a sulfur-rich pre-mix that is added to a base alloy composition. Forming a pre-mix provides improved homogeneity and distribution of the sulfur predominantly in the form of a metal sulfide.

Copper alloys exhibiting enhanced oxidation resistance are provided by adding an amount of sulfur that is effective to enhance oxidative resistance. Such sulfur addition can be achieved by combining elemental forms of copper and sulfur and heating the mixture to form a molten alloy, or by forming a sulfur-rich pre-mix that is added to a base alloy composition. Forming a pre-mix provides improved homogeneity and distribution of the sulfur predominantly in the form of a metal sulfide.

A conductive material for connection parts includes a matrix, a Cu—Sn alloy covering layer having a Cu content of 20 to 70 at % and an average thickness of from 0.2 to 3.0 μm, and a Sn covering layer having an average thickness of from 0.05 to 5.0 μm. The matrix is a copper alloy strip containing specified amounts of Cr and Zr or specified amounts of Fe and P, or a Cu—Zn alloy strip containing a specified amount of Zn. The Cu—Sn alloy covering layer and the Sn covering layer are formed in this order on a surface of the matrix.