| 摘要 |
PROBLEM TO BE SOLVED: To provide a ballpoint pen in which a ball hardly corrodes over an extended period of time and the light and smooth feel of the pen and lubricity are maintained.SOLUTION: In a ball for ballpoint pen, which is a WC-Co-based carbide ball, the ratio of Fe atoms to Co atoms is 0.5 wt.% or less in the depth range of from a ball outermost surface to 1 μm. |
