| 摘要 |
PURPOSE:To produce external parts for a watch having hard and fine black surface layers by adding a specified amount of Cr, Cu or Fe to Au and converting the added metal into nitride and sulfide by a sulfurizing and nitriding process. CONSTITUTION:At least one among Cr, Cu and Fe is added to Au by 1-40wt% to prepare Au alloy stock. The added metal is converted into nitride and sulfide by a sulfurizing and nitriding process to form a blackened and hardened surface layer on the stock. Thus, external parts of an Au alloy for a watch having fine black color are obtd. The parts are not scratched by daily use. |
