| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball for ball point pen made of cemented carbide and the manufacturing method for the same which will not spoil the taste of writing by the use of the same for a long period of time and excellent in anti-corrosive property. SOLUTION: The hard phase of the cemented carbide is constituted of at least one hard phase selected from tungsten carbide or the carbide, nitride, nitride carbide and mutual solid solution of the tungsten carbide and metals of group 4a, 5a and 6a in the periodic table and a composite carbide consisting of at least one bonding phase among W, Co, Ni, Cr and Mo, or at least one element of group 6a in the periodical table and carbon if necessary. The average grain size of the hard phase of the cemented carbide phase is specified so as to be less than 0.7 μm whereby the excellent taste of writing can be maintained for a long period of time and, further, 0.005-0.5 wt.% of aluminum is contained in the hard phase to improve anti-corrosive property whereby the prominent taste of writing can be obtained. |
