Corrosion-resistant trivalent-chromium chemical conversion coating and solution for trivalent-chromium chemical treatment
A trivalent-chromium chemical conversion coating from which substantially no hexavalent chromium is released. The trivalent-chromium chemical conversion coating is one formed on the surface of a zinc or zinc-alloy deposit. In a brine spray test, the chemical conversion coating has unsusceptibility t...
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Sprache: | eng ; fre ; ger |
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Zusammenfassung: | A trivalent-chromium chemical conversion coating from which substantially no hexavalent chromium is released. The trivalent-chromium chemical conversion coating is one formed on the surface of a zinc or zinc-alloy deposit. In a brine spray test, the chemical conversion coating has unsusceptibility to corrosion (time required for white-rust formation) of 96 hours or longer. The chemical conversion coating has a hexavalent-chromium concentration less than 0.01 µg/cm 2 in terms of metal atom amount. The amount of hexavalent chromium released after 30-day standing in a thermo-hygrostatic chamber at a temperature of 80°C and a humidity of 95% (amount of hexavalent chromium released when the coating is immersed in 100°C water for 10 minutes) is smaller than 0.05 µg/cm 2 . |
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