A surface-treated steel sheet for battery cases is provided which comprises a nickel-cobalt alloy layer formed at the outermost surface of a plane to be an inner surface of a battery case, wherein a Co/Ni value at the surface of the nickel-cobalt alloy layer is within a range of 0.1 to 1.5 as determined by Auger electron spectroscopy analysis.

A surface-treated steel sheet for battery cases is provided which comprises a nickel-cobalt alloy layer formed at the outermost surface of a plane to be an inner surface of a battery case, wherein a Co/Ni value at the surface of the nickel-cobalt alloy layer is within a range of 0.1 to 1.5 as determined by Auger electron spectroscopy analysis.

A method for producing a black plated resin part includes the steps of electroplating a resin substrate provided with an underlying plating layer in a trivalent chromium plating bath containing thiocyanic acid, to thereby form, on the underlying plating layer, a black chromium plating layer composed of trivalent chromium and having a thickness of 0.15 μm or more; and immersing the resin substrate provided with the black chromium plating layer in warm water at 30° C. or higher for a predetermined time. In the method, the amount of thiocyanic acid contained in the trivalent chromium plating bath, the temperature of the warm water, and the time of immersion of the resin substrate in the warm water are adjusted so that the black chromium plating layer exhibits a b* value of −1.7 or less based on the L*a*b* color system.

The present disclosure describes electrodeposited nanolaminate materials having layers comprised of nickel and/or chromium with high hardness. The uniform appearance, chemical resistance, and high hardness of the nanolaminate NiCr materials described herein render them useful for a variety of purposes including wear (abrasion) resistant barrier coatings for use both in decorative as well as demanding physical, structural and chemical environments.

The present disclosure describes electrodeposited nanolaminate materials having layers comprised of nickel and/or chromium with high hardness. The uniform appearance, chemical resistance, and high hardness of the nanolaminate NiCr materials described herein render them useful for a variety of purposes including wear (abrasion) resistant barrier coatings for use both in decorative as well as demanding physical, structural and chemical environments.

A method for post-treatment of a chromium finish surface to improve corrosion resistance comprising a) providing a substrate having a chromium finish surface, and at least one intermediate layer between the chromium finish surface and the substrate, selected from the group consisting of nickel, nickel alloys, copper and copper alloys, wherein the chromium finish surface is a surface of a trivalent chromium plated layer, obtained by electroplating the substrate, having the at least one intermediate layer, in a plating bath, the plating bath comprising chromium (III) ions; b) contacting the chromium finish surface with an aqueous solution, comprising a permanganate, at least one compound which is selected from a phosphorus-oxygen compound, a hydroxide, a nitrate, a borate, boric acid, a silicate, or a mixture of two or more of these compounds; c) forming a transparent corrosion protection layer onto the chromium finish surface during step b.

A method for post-treatment of a chromium finish surface to improve corrosion resistance comprising a) providing a substrate having a chromium finish surface, and at least one intermediate layer between the chromium finish surface and the substrate, selected from the group consisting of nickel, nickel alloys, copper and copper alloys, wherein the chromium finish surface is a surface of a trivalent chromium plated layer, obtained by electroplating the substrate, having the at least one intermediate layer, in a plating bath, the plating bath comprising chromium (III) ions; b) contacting the chromium finish surface with an aqueous solution, comprising a permanganate, at least one compound which is selected from a phosphorus-oxygen compound, a hydroxide, a nitrate, a borate, boric acid, a silicate, or a mixture of two or more of these compounds; c) forming a transparent corrosion protection layer onto the chromium finish surface during step b.

An aqueous electroplating bath is disclosed. The aqueous trivalent chromium bath comprises:—trivalent chromium cations in an amount of 0.12-0.276 mol/l,—ammonium ions in an amount of 4.0-6.0 mol/l, and—carboxylate ions in an amount of 2.0-7.4 mol/l, and the molar ratio of trivalent chromium cations to the carboxylate ions is 0.016-0.099, and the pH of the aqueous trivalent chromium bath is 2-6.

An aqueous electroplating bath is disclosed. The aqueous trivalent chromium bath comprises:—trivalent chromium cations in an amount of 0.12-0.276 mol/l,—ammonium ions in an amount of 4.0-6.0 mol/l, and—carboxylate ions in an amount of 2.0-7.4 mol/l, and the molar ratio of trivalent chromium cations to the carboxylate ions is 0.016-0.099, and the pH of the aqueous trivalent chromium bath is 2-6.

Provided is a plating method including performing a first masking that masks a first region and a second region among the first region including only a first metal and the second region including only a second metal in a clad metal having the first metal and the second metal cladded, and a third region including a contact part between the first metal and the second metal, precipitating the clad metal in a first plating solution, performing a second masking that removes the processed masking in one of the first region and the second region, precipitating at least the region where the second masking has been performed in a second plating solution, and precipitating the region where the second masking has been performed and the third region in a third plating solution.