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Article having a layer of a nickel-phosphorous alloy and coated with a protective layer
Article having a layer of a nickel-phosphorous alloy and coated with a protective layer
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机译:具有镍-磷合金层并涂覆有保护层的制品
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摘要
An article which covered with a nickel-phosphorus alloy and which is covered on its outer surface with a protective layer which comprises CrP04, Cr(OH)3 and may also comprise Cr2(SO4)3 and in which no nickel is present. The layer provides an excellent corrosion protection. In a particular embodiment the layer is black, scratch-resistant in normal use, cannot be wiped off and is not sensitive to finger prints and is extremely suitable for decorative applications. The layers can be obtained electrolytically in a bath which comprises chromic acid and optionally reserved current in a given frequency range, a given range of current densities and a given range of ratios of cathodic to anodic pulse durations. In order to obtain the black layers the cathodic time duration is only a fraction of black layers the anodic time duration.
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