| 摘要 |
PURPOSE:To maintain the quality of external parts for a pocket timepiece while retaining the appearance of silver by depositing pure silver on the surface of a silver alloy and by chromating the pure silver layer. CONSTITUTION:A silver alloy such as sterling silver is used as a base metal 1, and pure silver 2 is deposited on the surface of the base metal 1 by plating, vapor deposition or other method. The minimum thickness of the pure silver layer is adjusted to about 1,000Angstrom , and the hue of pure silver 2 is uniformly provided to the surface. A chromate or dichromate film 3 is then formed on the surface of the pure silver film. The treated surface has high mechanical strength and causes hardly discoloration in a sulfide atmosphere. |
