Abstract: The present invention provides for a zinc-based coated steel sheet having a zinc-based coating layer and a lubricant film, which is formed on the zinc-based coating layer, containing zinc phosphate particles in an amount of 50 wt. % or more, and having substantially no reaction layer formed by reaction between the zinc-based coating and the zinc phosphate particles, and a method for the manufacture thereof. The zinc-based coated steel sheet according to the present invention has an excellent anti-peeling property, excellent frictional property, even in the non-lubricated condition which occurs at areas where the press oil film is broken, and excellent anti-galling property.

Abstract: The present invention provides for a zinc-based coated steel sheet having a zinc-based coating layer and a lubricant film, which is formed on the zinc-based coating layer, containing zinc phosphate particles in an amount of 50 wt. % or more, and having substantially no reaction layer formed by reaction between the zinc-based coating and the zinc phosphate particles, and a method for the manufacture thereof. The zinc-based coated steel sheet according to the present invention has an excellent anti-peeling property, excellent frictional property, even in the non-lubricated condition which occurs at areas where the press oil film is broken, and excellent anti-galling property.

Abstract: The invention provides a material coated with an organic film which exhibits excellent corrosion resistance and lacquer adhesion. The invention includes an electroconductive substrate coated with an electrolytically polymerized coating film containing chromium. Particularly, a zinc-type plated steel sheet coated with an electrolytically polymerized coating film containing chromium in accordance with the invention is well suited for application in vehicle bodies. The invention further provides a method of making a material coated with an organic film which involves forming organic coating material containing chromium on an electroconductive substrate acting as an electrode by electrolytically polymerizing an organic monomer in an electrolyte solution containing chromium. The method provides a monolithic composite structure comprising chromium compounds and an organic coating film, and avoid the problems associated with passivation after chromium plating of steel.

Abstract: An organic film-coated plated steel sheet is disclosed which includes a base steel sheet, a zinc-base plated layer disposed thereon, and an organic film layer formed by cathodic polymerization of one or more monomers and superposed as an outermost layer on the zinc-base plated layer. The steel is excellent in corrosion resistance, weldability, electrodeposition paintability or paint adhesion and, thus, is suitable as a rust-proof steel sheet particularly for use in automobile bodies. Also disclosed is a process for producing that steel with less production equipment and reduced cost.

Abstract: The present invention provides a method of producing a zinc-chromium alloy-plated steel sheet having excellent properties such as bare corrosion resistance, corrosion resistance after coating, plating adhesiveness and weldability.The method is characterized by plating the surface of the steel sheet using an acid plating bath containing zinc ion (Zn.sup.2+) and chromium ion (Cr.sup.3+) at a molar concentration ratio of about 0.1.ltoreq.Cr.sup.3+ /(Zn.sup.3+ +Cr.sup.3+).ltoreq.0.9 in a total amount of at least about 0.5 mol/1 within the dissolution range, and about 0.1 to 30 g/1 of at least one nonionic organic additive having at least a triple bond, at a bath temperature of about 25.degree. to 70.degree. C. and a pH of about 1.0 to 4.0 with a current density of about 50 to 200 A/dm.sup.2.