| abstract |
(57) [Summary] [Problem] To make a wristwatch exterior part having a silvery luster inherent to titanium metal, making it hard to be finely scratched, and maintaining a beautiful surface gloss for a long time. It is to be. SOLUTION: The surface of a wristwatch exterior part made of titanium metal is formed of a carburized layer of Vickers hardness (HV) 500 or more made of titanium carbide and carbon solid solution titanium, and this carburized layer is formed on a silver glossy surface. The formed titanium metal watch exterior parts. Further, the titanium metal wristwatch exterior part was placed under a hydrocarbon-based gas pressure of 0.1 to 5 Torr and a pressure of 7 to 5 Torr. A carburizing layer made of titanium carbide and carbon solid solution titanium is formed by plasma carburizing treatment in an atmosphere of 00 to 900 ° C., and the method is a surface treatment method for a titanium metal wristwatch exterior part that is mirror-polished. |