A method for the galvanoplastic deposition of a gold alloy on an electrode dipped into a bath including gold metal, organometallic compounds, a wetting agent, a sequestering agent and free cyanide, the alloy metals being copper metal and silver metal allowing a mirror-bright yellow gold alloy to be deposited on the electrode characterized in that the bath respects a proportion of 21.53% gold, 78.31% copper and 0.16% silver.

A wire comprising a silver-based wire core having a double-layer coating comprised of an inner layer of palladium or nickel and an adjacent outer layer of gold, wherein the wire exhibits at least one of the intrinsic properties A1) to A3): A1) the average grain size of the crystal grains in the wire core, measured in longitudinal direction, is in the range of from 0.7 to 1.1 ?m; A2) the fraction of twin boundaries, measured in longitudinal direction of the wire, is in the range of from 5 to 40%; and, A3) 20 to 70% of the crystal grains of the wire core are oriented in <100> direction, and 3 to 40% of the crystal grains of the wire core are oriented in <111> direction, each % with respect to the total number of crystal grains with orientation parallel to the drawing direction of the wire.

A method for the galvanoplastic deposition of a gold alloy on an electrode dipped into a bath including gold metal, organometallic compounds, a wetting agent, a sequestering agent and free cyanide, the alloy metals being copper metal and silver metal allowing a mirror-bright yellow gold alloy to be deposited on the electrode characterized in that the bath respects a proportion of 21.53% gold, 78.31% copper and 0.16% silver.

A method for the galvanoplastic deposition of a gold alloy on an electrode dipped into a bath including gold metal, organometallic compounds, a wetting agent, a sequestering agent and free cyanide, the alloy metals being copper metal and silver metal allowing a mirror-bright yellow gold alloy to be deposited on the electrode characterized in that the bath respects a proportion of 21.53% gold, 78.31% copper and 0.16% silver.

The present invention provides an electrolytic hard gold plating solution substitution inhibitor characterized by containing at least one compound selected from the group consisting of an imidazole compound having a mercapto group, a triazole compound having a mercapto group, and an aliphatic compound having a sulfonic acid group and a mercapto group, and further provides an electrolytic hard gold plating solution containing said electrolytic hard gold plating solution substitution inhibitor, a gold salt, a soluble cobalt salt and/or a soluble nickel salt, an organic acid conducting salt, and a chelating agent.

The present invention provides an electrolytic hard gold plating solution substitution inhibitor characterized by containing at least one compound selected from the group consisting of an imidazole compound having a mercapto group, a triazole compound having a mercapto group, and an aliphatic compound having a sulfonic acid group and a mercapto group, and further provides an electrolytic hard gold plating solution containing said electrolytic hard gold plating solution substitution inhibitor, a gold salt, a soluble cobalt salt and/or a soluble nickel salt, an organic acid conducting salt, and a chelating agent.

A method of galvanoplastic deposition of a gold alloy on an electrode dipped into a bath including metal gold in alkaline aurocyanide form, organometallic compounds, a wetting agent, a sequestering agent and free cyanide, where the alloy metals are copper, in double copper and potassium cyanide form, and silver in cyanide form, allowing a mirror bright yellow gold alloy to be deposited on the electrode.

A method of galvanoplastic deposition of a gold alloy on an electrode dipped into a bath including metal gold in alkaline aurocyanide form, organometallic compounds, a wetting agent, a sequestering agent and free cyanide, where the alloy metals are copper, in double copper and potassium cyanide form, and silver in cyanide form, allowing a mirror bright yellow gold alloy to be deposited on the electrode.

A metal sheet for separators of polymer electrolyte fuel cells having both excellent corrosion resistance in the use environment of separators of polymer electrolyte fuel cells and excellent adhesion property between a substrate and a surface-coating layer even in the case where the surface-coating layer is made thinner is provided. A metal sheet for separators of polymer electrolyte fuel cells includes: a substrate made of metal; and a surface-coating layer with which the substrate is coated, with a strike layer in between, wherein a coating weight of the strike layer is 0.001 g/m.sup.2 to 1.0 g/m.sup.2.

A composition containing a cationic polymer obtained from a reaction product of nitrogen-containing heterocyclic compound and epihalohydrin; and a phosphorus compound. The composition can be used as a surface treatment for gold or gold alloy. The composition can seal pinholes on the surface of the gold or gold alloy.