Kawasaki Steel Corporation

Other

Hajime Ogata

Toshio Ichida

Kazuo Mochizuki

Toshio Irie

Shunichi Tsugawa

Kyoko Yamaji

Hisatada Nakakouji

Hideo Kobayashi

Hisatada Nakakoji

Koji Yamato

Kyoko Hamahara

Shunichi Harada

Yoshiharu Ohashi

Motoharu Hamada

Sachiko Otsuka

Yasuhiro Akeda

Kenichiro Akao

Toshihiro Kikuchi

A method of recovering and reproducing a tinning liquid containing Fe ions and other detrimental cations by the steps of removing cations from the tinning liquid by passing the tinning liquid or a diluted liquid of the tinning liquid through a strong-acid cation exchange resin to obtain a recovered acid, thereafter reproducing the strong-acid cation exchange resin and desorbing adsorbed cations into a solution containing an acid by passing the acid through the exchange resin to which the cations have been adsorbed, precipitating and separating Sn ions in the form of a precipitate of an Sn compound from the solution into which the cations have been desorbed while maintaining Fe ions as ions in this solution, mixing and dissolving the precipitate of the Sn compound or a compound reduced from the same in the recovered acid to reproduce and reuse the mixture of the Sn compound and the recovered acid as a tinning liquid, and discharging the solution containing Fe ions out of the system of the tinning liquid.

Method for recovering and reproducing tinning liquid

A surface-treated steel strip adapted for electric resistance welding is prepared by forming a first layer of iron-nickel alloy on a steel strip, said first layer having a weight ratio of Ni/(Fe+Ni) in the range between 0.02 and 0.50 and a thickness of 10 to 5,000 angstroms, forming a second layer of tin or iron-tin-nickel alloy on said first layer by tin plating to a coating weight of 0.1 to 1 g/m.sup.2 of tin and optionally, causing the tin to reflow, and forming a third layer on said second layer by effecting an electrolytic chromate treatment, said third layer consisting essentially of metallic chromium and hydrated chromium oxide, wherein the electrolytic chromate treatment is carried out in a bath which contains an amount of a chromate compound to give 10 to 100 g/l of CrO.sub.3 and has a weight ratio of H.sub.2 SO.sub.4 /CrO.sub.3 in the range between 3/1000 and 1/100.

Process for preparing surface-treated steel strips adapted for electric

A tin-free steel strip comprising a steel strip, 40 to 150 mg/m.sup.2 of a metallic chromium layer on the steel surface, and 5 to 25 mg/m.sup.2 of a chromium compound containing layer thereon wherein the metallic chromium layer contains a plurality of protrusions, exhibits improved corrosion resistance and weldability and is thus useful in the manufacture of welded cans. Preferably, 1.times.10.sup.11 to 1.times.10.sup.14 protrusions having a diameter of 5 to 1000 nm at the base thereof are present per square meter of the metallic chromium layer surface. The tin-free steel strip is produced by chromium plating a steel strip in an aqueous solution containing CR.sup.6+ preferably to a weight of 40 to 140 mg/m.sup.2, subjecting the chromium plated strip to anodic electrolysis, preferably at an eectricity quantity of 0.1 to 10 C/dm.sup.2, and subjecting the strip to a cathodic treatment in an aqueous solution containing Cr.sup.6+ and a chromium plating aid so as to deposit additional metallic chromium, preferably in a weight of 10 to 60 mg/m.sup.2.

Tin-free steel strips useful in the manufacture of welded cans and

Surface-treated steel strips suitable for electric resistance welding are prepared by forming a first layer of iron-nickel alloy on a steel strip, said first layer having a weight ratio of Ni/(Fe+Ni) in the range between 0.02 and 0.50 and a thickness of 10 to 5,000 angstroms, forming a second layer of tin or iron-tin-nickel alloy on said first layer by tin plating to a coating weight of 0.1 to 1 g/m.sup.2 of tin and optionally, causing the tin to reflow, and forming a third layer on said second layer by effecting an electrolytic chromate treatment, said third layer consisting essentially of metallic chromium and hydrated chromium oxide in a total amount of 5 to 20 mg/m.sup.2 calculated as elemental chromium. More preferably, the electrolytic chromate treatment is controlled such that at least 2 mg/m.sup.2 of metallic chromium is present in the third layer.

Surface-treated steel strips adapted for electric resistance welding

Tin-free steel sheets having intimately bonded metallic chromium and hydrated chromium oxide coatings thereon and possessing improved resistance to retorting treatment and improved adhesion to paint films to be applied thereon are produced by chromium plating a steel sheet in a chromium plating bath containing an assistant to deposit and form metallic chromium and hydrated chromium oxide coatings on the sheet surface, subjecting the sheet to reverse electrolysis in the same chromium plating bath to partially dissolve away the metallic chromium and hydrated chromium oxide coatings together with the assistant anions codeposited in the hydrated chromium oxide coating, rinsing the sheet with water, and thereafter subjecting the sheet to an electrolytic chromate treatment in an electrolytic chromate treating bath.

Method of producing tin-free steel sheets

A surface-treated steel strip comprising a steel substrate, islands of metallic tin distributed on one major surface of the steel substrate, and a chromate coating deposited on the substrate major surface to cover the tin islands can be coated with lacquer, baked and then seam welded into food cans.

Surface-treated steel strips seam weldable into cans

Surface-treated steel strips suitable for electric resistance welding are prepared by forming a first layer of iron-nickel alloy on a steel strip, this first layer having a weight ratio of Ni/(Fe+Ni) in the range between 0.02 and 0.50 and a thickness of 10 to 5,000 angstroms, forming a second layer of tin or iron-tin-nickel alloy on the first layer by tin plating to a coating weight of 0.1 to 1 g/m.sup.2 of tin and optionally, causing the tin to reflow. A third layer is formed on the second layer by effecting an electrolytic chromate treatment, this third layer consisting essentially of metallic chromium and hydrated chromium oxide in a total amount of 5 to 20 mg/m.sup.2 calculated as elemental chromium. Preferably, the electrolytic chromate treatment is controlled so that at least 2 mg/m.sup.2 of metallic chromium is present in the third layer.

Tin-free steel sheets having improved lacquer adhesion

Tin-free steel sheets having improved resistance to retorting treatment are produced by chromium plating a steel sheet through cathodic electrolysis in a chromium ion-containing aqueous solution to form a metallic chromium coating, reversely electrolyzing the chromium plated steel sheet by a successive anodizing treatment in the same solution, and subjecting the sheet to an electrolytic chromate treatment in another aqueous solution of chromic acid, a chromate or dichromate. The chromium plating and reverse electrolysis should be carried out so as to satisfy the equations:

Tin-free steel sheets exhibiting improved retorting resistance with respect to paint adhesion are produced by chromium plating a steel sheet through cathodic electrolysis in a chromium ion-containing solution, reversely electrolyzing the sheet by a successive anodizing treatment in said solution, and subjecting the sheet to an electrolytic treatment in an aqueous chromate solution. The SO.sub.4.sup.-- concentration of the chromate solution used in the electrolytic chromate treatment should be limited to the range of 0.01 to 0.10 gram per liter of the solution.

Growing community of inventors

Chiba, Japan

Hajime Ogata