A passivation surface treatment method of stainless steel that improves corrosion resistance including in a brine environment without changing the appearance of the surface of stainless steel. A passivation surface treatment method for stainless steel includes: performing degreasing of stainless steel, performing electrolytic pickling where the stainless steel that underwent the degreasing is immersed in a pickling solution having phosphoric acid (H.sub.3PO.sub.4) and is connected to the anode and a voltage of about 0.5 to 5.0 V for about 10 seconds or more is applied, performing electrolytic degreasing of the stainless steel, and performing electrolytic passivation where the stainless steel that underwent the electrolytic degreasing is immersed in a passivation solution including dichromic acid and chromium sulfate and a voltage of about 0.5 to 5.0 V is applied for 5 seconds or more.

A passivation surface treatment method of stainless steel that improves corrosion resistance including in a brine environment without changing the appearance of the surface of stainless steel. A passivation surface treatment method for stainless steel includes: performing degreasing of stainless steel, performing electrolytic pickling where the stainless steel that underwent the degreasing is immersed in a pickling solution having phosphoric acid (H.sub.3PO.sub.4) and is connected to the anode and a voltage of about 0.5 to 5.0 V for about 10 seconds or more is applied, performing electrolytic degreasing of the stainless steel, and performing electrolytic passivation where the stainless steel that underwent the electrolytic degreasing is immersed in a passivation solution including dichromic acid and chromium sulfate and a voltage of about 0.5 to 5.0 V is applied for 5 seconds or more.

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.

A surface treated copper foil 1 includes a copper foil 2, and a first surface treatment layer 3 formed on one surface of the copper foil 2. The first surface treatment layer 3 of the surface treated copper foil 1 has a root mean square gradient of roughness curve elements RΔq according to JIS B0601:2013 of 5 to 28°. A copper clad laminate 10 includes the surface treated copper foil 1 and an insulating substrate 11 adhered to the first surface treatment layer 3 of the surface treated copper foil 1.

Disclosed is a ferritic stainless steel with improved corrosion resistance. The ferritic stainless steel with improved corrosion resistance according to an embodiment of the present disclosure includes, in percent (%) by weight of the entire composition, C: 0.02% or less (excluding 0), N: 0.02% or less (excluding 0), Si: 0.5% or less (excluding 0), Mn: 0.3% or less (excluding 0), Cr: 16 to 20%, Ni: 0.4% or less (excluding 0), the remainder of iron (Fe) and other inevitable impurities, and a Cr weight % content of a thickness region from a surface of a passivation film to 3 nm is 1.2 times or more than the Cr weight % content of the stainless base material.

Disclosed is a ferritic stainless steel with improved corrosion resistance. The ferritic stainless steel with improved corrosion resistance according to an embodiment of the present disclosure includes, in percent (%) by weight of the entire composition, C: 0.02% or less (excluding 0), N: 0.02% or less (excluding 0), Si: 0.5% or less (excluding 0), Mn: 0.3% or less (excluding 0), Cr: 16 to 20%, Ni: 0.4% or less (excluding 0), the remainder of iron (Fe) and other inevitable impurities, and a Cr weight % content of a thickness region from a surface of a passivation film to 3 nm is 1.2 times or more than the Cr weight % content of the stainless base material.

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.

A method for electrolytically passivating a surface of silver, silver alloy, gold, or gold alloy, the method comprising the steps of (i) providing a substrate comprising the surface, (ii) providing an aqueous passivation solution comprising trivalent chromium ions, and one or more than one species of carboxylic acid residue anions, (iii) contacting the substrate with the passivation solution and passing an electrical current between the substrate as a cathode and an anode such that a passivation layer is electrolytically deposited onto the surface, wherein the trivalent chromium ions with respect to all species of carboxylic acid residue anions form a molar ratio in the range from 1:10 to 1:400.