| 摘要 |
1489023 Chromated zinc-plated steel NIPPON KOKAN KK 24 Dec 1975 [22 Jan 1975] 53277/75 Heading C7B Steel is electrolytically zinc plated from an acidic zinc bath containing (A) 50-700 ppm of Cr<SP>3+</SP> or 50-500 Cr<SP>6+</SP> or 50-700 ppm combined Cr<SP>3+</SP> and Cr<SP>6+</SP>, with Cr<SP>6+</SP> not exceeding 500 ppm and (B) 10-5000 ppm Sn ions and/or 10-30,000 ppm In ions, and is thereafter conventionally chromated. The Zn bath may contain Zn sulphate and/or chloride, an NH4 salt as conductor and Na acetate or succinate as buffer. The metal ions may come from the following sources; Cr<SP>3+</SP> -sulphate, nitrate or Cr/ammonium sulphate; Cr<SP>6+</SP> -(bi)chromic acid or alkali metal or ammonium salt thereof; Sn from Sn<SP>2+</SP> or Sn<SP>4+</SP> sulphate or chloride; In-sulphate or chloride. |
