PRODUCTION OF ELECTROLYTICALLY CHROMATED GALVANIZED STEEL SHEET EXCELLENT IN RESISTANCE TO CORROSION, FINGERPRINTING AND CHROMIUM ELUTION AND IN CONTINUOUS PRODUCTIVITY AND ELECTROLYTIC CHROMATING BATH USED IN THAT CASE

摘要

PURPOSE: To propose a method for producing an electrolytically chromated galvanized steel sheet excellent in resistance to corrosion, fingerprinting and chromium elution and in continuous productivity and to provide an electrolytic chromating bath used in that case. ;CONSTITUTION: A galvanized steel sheet with at least one side galvanized or zinc-plated is used as a cathode. The steel sheet is electrolytically chromated in an electrolytic chromating bath contg. hexavalent chromium ion, trivalent chromium ion, bivalent Ni ion, silica sol, phosphate ion and sulfate ion, wherein trivalent chromium ion concn. in the bath/total chromium ion concen. 0.1 and the silica concn. in the bath/trivalent chromium ion concen. 70 and kept at pH2.5-3.8 and at 30-70°C to form an electrolytic chromate film on the galvanized or zinc-plated layer.;COPYRIGHT: (C)1996,JPO