[Problem] There is provided a colored stainless-steel product having excellent viewing-angle color tone discrimination and excellent corrosion resistance, in which a chemical coloration technique having sophisticated industrial color tone is used. [Solution] The product is a chemically-colored stainless-steel product having an uneven surface formed by a grinding treatment, wherein the 60-degree specular gloss [Gs (60 degrees)] of the uneven surface is 5 to 50. The grinding treatment is performed by a single sandblasting treatment or a combination of the sandblasting treatment and an electrolytic polishing treatment. The sandblasting treatment is performed with a projection material configured from inorganic particles having a Mohs' hardness of at least six. A manufacturing method includes a sandblasting treatment step, an electrolytic polishing treatment step, a coloration treatment step for dipping stainless steel in a coloration treatment solution including a mixed solution of a chromic acid and a sulfuric acid to generate a colored film thereon, and a curing treatment step for dipping the coloration-treated stainless steel in a curing treatment solution including a mixed solution of a chromic acid and a phosphoric acid to cure the colored film.

[Problem] There is provided a colored stainless-steel product having excellent viewing-angle color tone discrimination and excellent corrosion resistance, in which a chemical coloration technique having sophisticated industrial color tone is used. [Solution] The product is a chemically-colored stainless-steel product having an uneven surface formed by a grinding treatment, wherein the 60-degree specular gloss [Gs (60 degrees)] of the uneven surface is 5 to 50. The grinding treatment is performed by a single sandblasting treatment or a combination of the sandblasting treatment and an electrolytic polishing treatment. The sandblasting treatment is performed with a projection material configured from inorganic particles having a Mohs' hardness of at least six. A manufacturing method includes a sandblasting treatment step, an electrolytic polishing treatment step, a coloration treatment step for dipping stainless steel in a coloration treatment solution including a mixed solution of a chromic acid and a sulfuric acid to generate a colored film thereon, and a curing treatment step for dipping the coloration-treated stainless steel in a curing treatment solution including a mixed solution of a chromic acid and a phosphoric acid to cure the colored film.

A steel sheet for cans which exhibits excellent weldability; and a production method therefore include the surface of a steel sheet in order from the steel sheet side, a chromium metal layer and a hydrous chromium oxide layer. The deposited amount of the chromium metal layer is 50-200 mg/m.sup.2. The deposited amount of the hydrous chromium oxide layer in terms of chromium is 3-30 mg/m.sup.2. The chromium metal layer includes: a base part having a thickness of 7.0 nm or higher; and granular protrusions which are on the base part, have a maximum grain size of 200 nm or lower, and have a number density per unit area of at least 30 per m.sup.2.

A steel sheet for cans which exhibits excellent weldability; and a production method therefore include the surface of a steel sheet in order from the steel sheet side, a chromium metal layer and a hydrous chromium oxide layer. The deposited amount of the chromium metal layer is 50-200 mg/m.sup.2. The deposited amount of the hydrous chromium oxide layer in terms of chromium is 3-30 mg/m.sup.2. The chromium metal layer includes: a base part having a thickness of 7.0 nm or higher; and granular protrusions which are on the base part, have a maximum grain size of 200 nm or lower, and have a number density per unit area of at least 30 per m.sup.2.

A steel sheet for cans has, on the surface thereof, in order from the steel sheet side, a chromium metal layer and a hydrous chromium oxide layer. The chromium metal layer is deposited in an amount of 50-200 mg/m.sup.2, and the hydrous chromium oxide layer is deposited in an amount of 3-15 mg/m.sup.2 in terms of chromium. The chromium metal layer includes: a flat chromium metal layer that has a thickness of at least 7 nm; and a granular chromium metal layer that includes granular protrusions that are formed on the surface of the flat chromium metal layer. The maximum grain size of the granular protrusions is 150 nm or smaller. The number density of the granular protrusions per unit area is 10/m.sup.2 or higher.

A steel sheet for cans has, on the surface thereof, in order from the steel sheet side, a chromium metal layer and a hydrous chromium oxide layer. The chromium metal layer is deposited in an amount of 50-200 mg/m.sup.2, and the hydrous chromium oxide layer is deposited in an amount of 3-15 mg/m.sup.2 in terms of chromium. The chromium metal layer includes: a flat chromium metal layer that has a thickness of at least 7 nm; and a granular chromium metal layer that includes granular protrusions that are formed on the surface of the flat chromium metal layer. The maximum grain size of the granular protrusions is 150 nm or smaller. The number density of the granular protrusions per unit area is 10/m.sup.2 or higher.

The present invention provides a surface treated copper foil in which a dropping of the roughening particles from a roughening treatment layer provided on the surface of the copper foil is favorably suppressed and an occurrence of wrinkles or stripes when bonding with an insulating substrate is favorably suppressed. The surface treated copper foil comprises a copper foil, and a roughening treatment layer on at least one surface of the copper foil, wherein an aspect ratio of roughening particles of the roughening treatment layer satisfies one or more of the following items (1) and (2), the aspect ratio being a height of the roughening particles/a thickness of the roughening particles: (1) the aspect ratio of the roughening particles is 3 or less, (2) the aspect ratio of the roughening particles satisfies any one of the following items (2-1) or (2-2): (2-1) the aspect ratio of the roughening particles is 10 or less in the case that the height of the roughening particles is more than 500 nm and 1000 nm or less, (2-2) the aspect ratio of the roughening particles is 15 or less in the case that the height of the roughening particles is 500 nm or less; and a glossiness of a TD of the surface of the side of the roughening treatment layer of the surface treated copper foil is 70% or less.

A method for electrolytically passivating an outermost chromium or chromium alloy layer to increase corrosion resistance thereof, including steps of (i) providing a substrate comprising said outermost chromium or chromium alloy layer, (ii) providing or manufacturing an aqueous, acidic passivation solution comprising trivalent chromium ions, phosphate ions, one or more organic acid residue anion, (iii) contacting the substrate with the passivation solution and passing an electrical current between the substrate as a cathode and an anode in the passivation solution such that a passivation layer is deposited onto the outermost layer, wherein the trivalent chromium ions are obtained by chemically reducing hexavalent chromium in presence of phosphoric acid and at least one reducing agent, with the proviso that during or after the chemical reducing the one or more than one organic acid residue anion is present for the first time in the passivation solution.

A method for electrolytically passivating an outermost chromium or chromium alloy layer to increase corrosion resistance thereof, including steps of (i) providing a substrate comprising said outermost chromium or chromium alloy layer, (ii) providing or manufacturing an aqueous, acidic passivation solution comprising trivalent chromium ions, phosphate ions, one or more organic acid residue anion, (iii) contacting the substrate with the passivation solution and passing an electrical current between the substrate as a cathode and an anode in the passivation solution such that a passivation layer is deposited onto the outermost layer, wherein the trivalent chromium ions are obtained by chemically reducing hexavalent chromium in presence of phosphoric acid and at least one reducing agent, with the proviso that during or after the chemical reducing the one or more than one organic acid residue anion is present for the first time in the passivation solution.

The invention relates to a system for applying a superimposed time-varying frequency electromagnetic wave to a target object or a target region that is formed by the target object and a medium surrounding the target object, comprising a device for generating a superimposed time-varying frequency electromagnetic wave where the time-varying AC wave is riding on the predefined DC bias voltage. When applied to the object or region, the superimposed time-varying frequency electromagnetic wave is able to induce a flow of ionic current having a DC component traveling in a pulsating and time-varying manner in the target object and/or in the medium and effect induced vibration of electrons and molecules of the target object and the medium. The invention also relates to a method applying a superimposed time-varying frequency electromagnetic wave to a target object or a target region. The method and the system of the invention significantly reduce the capital cost and require very low energy, with the environmentally friendly final products, and are able to result in various treatment effects simultaneously.