| 摘要 |
A process for providing surface layers of copper or copper alloyed with zinc on die castings of zinc or zinc alloys comprises a step of immersing the castings in an agitated bath containing an aqueous vehicle, which has been adjusted to a pH of from 8 to 10, and to which cupric oxide has been added as a powder in an amount of approximately from 200 to 250 grams per liter of the agitated bath. Cuprous oxide may be substituted for cupric oxide. At a pH not exceeding 8.5, the surface layer tends to be copper alloyed with zinc. At a pH exceeding 8.5, the surface layer tends to be copper. At a pH of 9, the surface layer of copper tends to be very adherent. The pH is adjusted by addition of sodium hydroxide, potassium hydroxide, or ammonium hydroxide, preferably sodium hydroxide.
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