METHOD FOR CHROMATE TREATMENT OF GALVANIZED SHEET IRON

• Main Authors: SUDA, ARATA, OGINO, TAKAO
• Format: Patent
• Language: English; Japanese
• Published: 05.03.1992
• 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

The surface of galvanized sheet iron is coated with a water-base chromate treatment prepared by adding sulfate ions, nitrate and/or hydrofluoride ions and metallic ions such as Co, Ni, Sn, Cu, Fe and/or Pb to an aqueous solution containing 4.0 to 51.0 g/l of Cr (VI), 6.0 to 38.0 g/l of Cr (III) and 0.5 to 97.0 g/l of phosphate ions and having a Cr (III) to Cr (VI) ratio of 0.2 to 1.4 by weight, and the coated surface is dried without washing with water to form thereon a chromatic coating in a coating weight of 20 to 160 mg/m in terms of chromium. La surface d'une tôle de fer galvanisée est recouverte d'un bain de traitement au chromate à base d'eau qu'on prépare en ajoutant des ions sulfate, des ions nitrate et/ou hydrofluorure et des ions métalliques, tels que Co, Ni, Sn, Cu, Fe et/ou Pb, à une solution aqueuse contenant 4,0 à 51,0 g/l de Cr (VI), 6,0 à 38,0 g/l de Cr (III) et 0,5 à 97,0 g/l d'ions phosphate et ayant un rapport Cr (III)/CR (VI) compris entre 0,2 et 1,4 en poids, et la surface ainsi revêtue est séchée sans lavage à l'eau pour qu'il se forme sur elle un revêtement de chrome selon un poids correspondant au chrome compris entre 20 et 160 mg/m2.