CHROMATE TREATMENT FOR GALVANIZED STEEL PLATE

• Main Authors: SUDA ARATA, AOKI TAKAYUKI, KOGA MITSUYUKI, OGINO RIKUO
• Format: Patent
• Language: English
• Published: 21.05.1992
• 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:To improve corrosion resistance, alkali resistance, welding resistance, workability, and adhesion property for coating material of a chromate film by specifying the amts. of hexavalent Cr ion, trivalent Cr ion, total Cr, silica sol, silane coupling agent, and phosphate ion in a chromate treating liquid. CONSTITUTION:The chromate treating liquid is prepared to contain 3.5-50.0g/l hexavalent Cr ion, 2.O-40.0g/l trivalent Cr ion, 1.0-100g/l phosphate ion, 0.1-1.2 weight ratio of silica sol to total Cr ion, and 0.05-0.3 molar ratio of silane coupling agent to hexavalent Cr ion. The weight ratio of trivalent Cr/hexavalent Cr is specified to 0.25-1.5 and phosphate ion to the total Cr ion to 0.1-1.2. This chromate treating liquid is applied on the surface of galvanized steel plate by coating and dried to form a chromate film containing 10-150mg/m Cr deposition amt.