ZINC ALLOYED PLATING STEEL SHEET HAVING SUPERIOR PHOSPHATE TREATING PROPERTY AND METHOD FOR MANUFACTURING THE SAME

• Main Authors: AHN, DEOK SU, KIM, YEONG BONG
• Format: Patent
• Language: English; Korean
• Published: 04.07.2001
• Edition: 7
• Subjects: CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; METALLURGY; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION

PURPOSE: A plating steel sheet and a method for manufacturing the same are provided in which phosphate treating property is substantially improved by finely eutectoid zinc, a metal having a larger corrosion potential difference than a zinc plating layer bismuth or bismuth hydroxide on the plating layer. CONSTITUTION: In a plating steel sheet of which surface is pre-treatment plated for improving phosphate treating property, the zinc alloyed plating steel sheet having superior phosphate treating property is characterized in that a zinc alloy containing 0.1 to 5 wt.% of bismuth, 5 to 30 wt.% of chromium and a balance of zinc is coated on the steel sheet in an amount of 0.1 g/m2 or more in the pre-treatment plating. In a method for manufacturing a plating steel sheet by performing pre-treatment plating for improving phosphate treating property, the method is characterized in that the pre-treatment plating is performed using a plating solution comprising 15 to 60 g/l of Zn¬2+ ions, 10 to 50 g/l of Cr¬3+ ions, 0.05 to 2.5 g/l of Bi¬+3 ions, 50 to 300 g/l of supplementary conductor material and 0.3 to 1.3 times of mole ratio of Cr¬3+ ion concentration of EDTA, and having a pH in the range of 1.2 to 4.2.