METAL MOLD FOR GLASS MOLDING AND MOLDING OF GLASS PRODUCT FOR CATHODE-RAY TUBE

摘要

PURPOSE: To obtain a metal mold for glass molding excellent in releasing and oxidation resisting properties and hardly forming a flaw on the surface of the glass by specifying the crystal structure of the plated membrane of a nickel- or a cobalt-based alloy on the outermost surface of a stainless steel metal mold. CONSTITUTION: This metal mold for glass molding is produced by forming an alloy membrane containing nickel or cobalt as a major component and consisting of fine crystals of <=20nm average diameter or crystals of >=1μm crystal diameter on the surface of a stainless steel mold base body. Thus, the crystal structure of the outermost surface is formed as a structure consisting of either extremely fine crystal particles having undeveloped crystalline particle boundaries close to an amorphous state even at a high temperature in the molding of a molten glass or coarse large crystals grown along the direction of the surface of the base body. In this way, a membrane having the extremely small in diffusion of the metal element generated by passing through the crystalline boundaries is obtained, and the formation of a chemically and mechanically stable oxide membrane tends to proceed when compared with the conventional membrane and the proceeding of an oxidation in the thickness direction of the membrane is suppressed to greatly improve the metal mold life.