| 摘要 |
PURPOSE:To let the colored galvanized products free from uneven coloring be obtained with a simple process by applying composite electrolytic galvanizing containing Co or Ni to a steel plate, heating the same and subjecting the same to post heat treatment using silicic acid base, etc. and heat treatment. CONSTITUTION:A steel base material is treated in the acidic electrolytic galvanizing bath added with one or more kinds of water-soluble Co, Ni compounds such as CoSO4 and NiSO4 as metals at 3-50g/l and added with one or more kinds of water-soluble or water-dispersible polyacrylate copolymer, dicyandiamide, formaldehyde, polyvinyl alcohol, cationic polyamine at 0.1-10g/l, whereby it is applied with electrolytic zinc plating. Thence, it is rinsed and is then coated with the aqueous solution containing silicic acid (salt) and chromic acid (salt) such as calcium silicate solution so that the silicon pickup becomes 10-400mg/m<2>. After drying, it is next heated to 300-600 deg.C to let the zinc surface color to blue black or the like. |
