[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 method of preparing a modified-metal surface by attaching a phosphorous-based acid to a surface of a metal: preparing a solution of the phosphorous-based acid in a protic solvent; immersing a strip of a metal work piece into the solution of the phosphorous-based acid, immersing a strip of a reference metal into the solution of the phosphorous-based acid, supplying a voltage for a duration of time, removing the metal work piece, cleaning the metal work piece, and drying the cleaned metal work piece under an inert atmosphere to obtain a modified metal work piece.

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.

A corrosion resistant anode is provided for oxygen evolution reaction in water including chloride ions. The anode includes: (1) a substrate; (2) a passivation layer coating the substrate; and (3) an electrocatalyst layer coating the passivation layer. Polyanion adjusted alkaline seawater electrolyte for hydrogen generation by electrolysis is also provided.

A corrosion resistant anode is provided for oxygen evolution reaction in water including chloride ions. The anode includes: (1) a substrate; (2) a passivation layer coating the substrate; and (3) an electrocatalyst layer coating the passivation layer. Polyanion adjusted alkaline seawater electrolyte for hydrogen generation by electrolysis is also provided.

A method of preparing a modified-metal surface. The method includes preparing a solution of a phosphorous-based acid in a solvent; immersing a strip of the metal work piece into the solution of the phosphorous-based acid; immersing a strip of a reference metal into the solution of the phosphorous-based acid; supplying a voltage for a duration of time to prepare a phosphorous acid-modified metal work piece; removing the phosphorous acid-modified metal work piece; cleaning and drying the phosphorous acid-modified metal work piece; applying a chitosan solution to the surface in order to attach chitosan/modified chitosan to the phosphorous acid based modified surface; prepare the modified-metal surface; and cleaning and drying the modified-metal surface.

A method of preparing a modified-metal surface. The method includes preparing a solution of a phosphorous-based acid in a solvent; immersing a strip of the metal work piece into the solution of the phosphorous-based acid; immersing a strip of a reference metal into the solution of the phosphorous-based acid; supplying a voltage for a duration of time to prepare a phosphorous acid-modified metal work piece; removing the phosphorous acid-modified metal work piece; cleaning and drying the phosphorous acid-modified metal work piece; applying a chitosan solution to the surface in order to attach chitosan/modified chitosan to the phosphorous acid based modified surface; prepare the modified-metal surface; and cleaning and drying the modified-metal surface.

A method of preparing a modified-metal surface by attaching a phosphorous-based acid to a surface of a metal: preparing a solution of the phosphorous-based acid in a protic solvent; immersing a strip of a metal work piece into the solution of the phosphorous-based acid, immersing a strip of a reference metal into the solution of the phosphorous-based acid, supplying a voltage for a duration of time, removing the metal work piece, cleaning the metal work piece, and drying the cleaned metal work piece under an inert atmosphere to obtain a modified metal work piece.