| 摘要 |
Black chromium plated magnesium alloy die castings, may have insufficient sealant and/or adhesive deposits and/or are defective because of surface scratches or discolourations. They are electrolytically re-treated by a continuous, cyclic, automatic, computer-controlled process. An electrolytic re-treatment process for the black chromium plated magnesium (especially aluminium-magnesium) alloy die castings, described above, comprises the following continuous, cyclic, automatic, computer-controlled operations of (a) removing sealant and/or adhesive strips from the manually racked castings using an alkaline bath containing added nonionic or ionic surfactants; (b) removing the chromium plate using a de-chroming bath; (c) subjecting the exposed nickel, copper or tin-bronze intermediate layer surfaces to optional sand blasting, rinsing, activation, rinsing, re-plating with the intermediate layer, rinsing, black chromium plating and rinsing; (d) blow drying, de-racking and vide-optically inspecting for surface flaws; (e) impregnating optionally partially sand blasted surface regions of the flaw-free castings; and (f) re-metallising certain surface regions of the castings.
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