| 摘要 |
PURPOSE:To remarkably improve the corrosion resistance of hands for a wrist watch by forming a chromium oxide film on the surfaces of the pinholes in the plated noble metallic layer of the hand. CONSTITUTION:A hand for a wrist watch is usually obtd. by plating brass as a base with a noble metal so as to improve the appearance. The formed noble metallic layer is thin, so the zinc in the brass is electrically corroded through the pinholes in the noble metallic layer. In order to prevent the corrosion, the pinholes are sealed by forming a chromium oxide film on the surfaces of the pinholes.
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