| 摘要 |
PROBLEM TO BE SOLVED: To lighten the wear of a nib body, and maintain a favorable writing feeling for a long period of time by specifying the hardness of a sintered body wherein a rigid intermetallic compound particle is sintered with a binder metal. SOLUTION: For this ball 1, a sintered body for which a rigid intermetallic compound particle 17 like WC is sintered with a binder metal 18 such as Co is formed into a sphere, and the surface 19 is finished by polishing into a mirror finished surface. Then, the hardness is preferably Hv(Vickers hardness) 1800 or higher, and Hv 1900 or higher is more preferable, and Hv 2000 or higher is most preferable. By this constitution, the layer of the binder metal 18 in gaps between the intermetallic compound particles 17 becomes extremely thin, and a fine piece of the intermetallic compound 17, which is exposed at the section of the binder metal 18 on the surface 19, becomes very small and less, and the wear of a nib body is prevented from occurring, and also, a favorable writing feeling is maintained extending to a long period of time. |
