| 摘要 |
PURPOSE:To improve durability, by impregnating a glass material having a composition whose softening temperature exceeds the temperature of a molten metal into air hole parts of a surface layer at a part, which is contacted with the liquid surface of the molten metal of a carbon tip, and exposing a part into which the glass material is not impregnated. CONSTITUTION:A carbon tip 1 which is formed by sinterig is of an approximately circular cylinder rod shape as a whole. A sharp conical tip part 2 is provided at the lower end of the tip. A heat resisting glass material 5 is impregnated in air hole 4 in the surface part, which are yielded when the carbon tip 1 has been sintered and formed. Thus a glass impregnated layer is formed. A surface 6 of the carbon tip 1 around each air hole 4 is exposed to the outside. When the tip is imersed in the molten metal, the part is directly contacted with the molten metal. As the heat resisting glass material that forms the glass impregnating layer, a material having a composition whose softening temperature exceeds the temperature of the molten metal is adopted. Lead glass, borosilicate glass, silicate glass, phosphate glass, and the like can be used as said material. |
