Verfahren zur Herstellung von Stahlprodukten mit einem Film aus hydratisiertem Chromoxyd mit ausgezeichneter Oberflaechenbeschaffenheit

摘要

1,253,422. Electro-depositing hydrated chromium oxide. NIPPON STEEL CORP. March 25, 1969 [March 28, 1968], No. 15480/69. Heading C7B. An adherent hydrated chromium oxide film is produced on iron or steel sheet, which may be Cr- Zn- or Sn-plated, by continuously passing the sheet 1 as a cathode alternatively over conductor rolls 4 provided with hold-down rolls 3 and under sink rolls 5 submerged in an electrolyte containing hexavalent Cr, e.g. an aqueous solution of 45 g/l CrO 3 and 0.4 g/l H 2 SO 4 past anodes 6, and pressing the electro-deposited film while still wet by a levelling roll 7 of surface hardness 40 to 90 degrees in the Shore Durometer hardness (A) scale after the coated steel has passed from the electrolyte between a hold-down roll 31and a conductor roll 41. The levelling roll is preferably lined with elastic rubber or resin, e.g. chloroprene rubber, polypropylene, vinylidene chloride, chlorinated polyethylene-vinyl chloride, or chlorosulphonated polyethylene resin. The film may be further pressed by rolls after the levelling roll and before a heating and drying step.