Abstract: A surface treatment solution for a plated steel sheet to be hot-pressed comprising a ZnO aqueous dispersion (A) and a water dispersible organic resin (B), wherein the ZnO aqueous dispersion (A) comprises water and ZnO particle size having 50 to 300 nm particles, the water dispersible organic resin (B) has a 5 to 45 mgKOH/g acid value and 5 to 300 nm emulsion particle size, and a mass ratio (WA/WB) of a mass of ZnO particles in the ZnO aqueous dispersion (WA) to a mass of solid content of the water dispersible organic resin (WB) is 30/70 to 95/5.

Abstract: A surface treatment solution excellent in stability during storage forming a coating for treatment excellent in waterproofness, solvent resistance, and adhesion with a plated steel sheet and able to provide a surface treated steel sheet with hot-pressing lubricity, chemical convertability after hot-pressing, corrosion resistance after coating, and spot weldability, that is, a surface treatment solution for a plated steel sheet to be hot-pressed comprising a ZnO aqueous dispersion (A) and a water dispersible organic resin (B), wherein the ZnO aqueous dispersion (A) comprises water and ZnO particle size having 50 to 300 nm particles, the water dispersible organic resin (B) has a 5 to 45 mgKOH/g acid value and 5 to 300 nm emulsion particle size, and a mass ratio (WA/WB) of a mass of ZnO particles in the ZnO aqueous dispersion (WA) to a mass of solid content of the water dispersible organic resin (WB) is 30/70 to 95/5.

Abstract: An aqueous treating solution for an Sn-based plated steel sheet, comprising (A) an organic material, (B) a water-soluble chromium compound, (C) a water-dispersible silica, and water, wherein the organic material (A) is at least one member selected from an oxy-acid with the ratio of hydroxyl group/carboxyl group in one molecule being from 3/1 to 10/1, its lactone form and an oxide derivative thereof, the water-soluble chromium compound (B) does not contain hexavalent chromium, and pH is from 0.7 to 6.0.

Abstract: An aqueous treating solution for an Sn-based plated steel sheet, comprising (A) an organic material, (B) a water-soluble chromium compound, (C) a water-dispersible silica, and water, wherein the organic material (A) is at least one member selected from an oxy-acid with the ratio of hydroxyl group/carboxyl group in one molecule being from 3/1 to 10/1, its lactone form and an oxide derivative thereof, the water-soluble chromium compound (B) does not contain hexavalent chromium, and pH is from 0.7 to 6.0.

Abstract: A hexavalent chromium-free surface treating agent for Sn- or Al-based coated steel sheet, comprising a trivalent chromium compound (A), a water-dispersible silica (B), a lubricity imparting component (C) made of one or more waxes of polyolefin wax, fluorine-containing wax and paraffin wax, and water, a mass ratio on the solid content basis of the water-dispersible silica (B) to the lubricity imparting component (C), (B)/(C), being within a range from 5/95 to 95/5.

Abstract: A hexavalent chromium-free surface treating agent for Sn- or Al-based coated steel sheet, comprising a trivalent chromium compound (A), a water-dispersible silica (B), a lubricity imparting component (C) made of one or more waxes of polyolefin wax, fluorine-containing wax and paraffin wax, and water, a mass ratio on the solid content basis of the water-dispersible silica (B) to the lubricity imparting component (C), (B)/(C), being within a range from 5/95 to 95/5.

Abstract: A chromate treatment bath composition, afforded by the introduction, into an aqueous solution containing hexavalent Cr ions and trivalent Cr ions, of a nonionic-anionic composite surfactant that has an anionic moiety and a nonionic moiety composed of a polyethylene glycol group or a group consiting of an ethylene oxide addition polymer, provides metal surfaces onto which a layer of the composition containing 5 to 150 mg/m.sup.2 of total chromium is dried with a chromate film that has an excellent alkali resistance and water resistance, a high chromium fixing ratio, an excellent corrosion resistance, and an excellent paint film adherence.

Abstract: The protection against black and white rust on zinciferous surfaces by a conventional chromating treatment is improved by drying into place on the zinciferous surface before chromating a pre-treatment composition that contains hexavalent chromium ion plus one or more salts of nickel and cobalt, in an amount to produce an add-on of 0.5 to 100 mg/m.sup.2 of metal.

Abstract: To form a darkening-resistant chromate ram on the surface of a galvanized steel sheet, the surface of the galvanized steel shut is treated with a phosphate treatment solution before it is chromate-treated in such a way that zinc phosphate crystals will cover from 10-60% of the substrate surface.

Abstract: Drying into place a covering of an aqueous solution of nickel and/or cobaltous sulfate and/or phosphate salts on a zinc or zinc alloy surface improves at least one of the blackening resistance and corrosion resistance after subsequent chromating treatment and the corrosion resistance and paint adherence after subsequent chromating treatment and painting.