| 摘要 |
PURPOSE:To suppress the deterioration of the surface and increase the durability by making the parts contacting with glass, a specific composition containing W, Ti and C with a specific 2-phase mixed structure. CONSTITUTION:A WC powder, a TiC powder, or a powder of TiC and WC solid solution are mixed at a prescribed weight ratio, press molded, and the molded product is sintered at elevated temperature and processed into the final form of the optical element whereby the molds for forming the optical element are prepared. The resultant mold has, at least at the parts contacting with glass, a composition containing 65.2 to 92.9wt.% of W, 24 to 0.8wt.% of Ti, 10.3 to 6.1wt.% of C and the rest of unavoidable contaminants. Moreover, it has a 2-phase mixed structure comprising the first WC phase and the second solid solution phase of NaCl type crystals of complex carbides of Ti and W. The resultant molds are suitably used in press-molding of lenses and prisms. |
