| 摘要 |
PROBLEM TO BE SOLVED: To provide ultrafine particle cemented carbide which is used, e.g. for drilling, milling and cutting such as a PCB drill.SOLUTION: The ultrafine particle cemented carbide is obtained by binding tungsten carbide particles having the average particle diameter of ≤0.3 μm with a binder phase essentially consisting of Co. The cemented carbide includes, by mass, 2.0 to 8.0% Co, 0.10 to 0.90% V and 0.06 to 0.80% Cr, and in which the mass ratio between the V content and the Co content (V/Co) is 0.05 to 0.12, the mass ratio between the Cr content and the Co content (Cr/Co) is 0.03 to 0.10, the mass ratio between the total of the V content and the Cr content and the Co content (V+Cr)/Co is 0.11 to 0.20 and the mass ratio between the V content and the Cr content (V/Cr) is 1.10 to 1.90, has the maximum particle diameter of ≤0.3 μm (not including zero), and has a structure in which a V concentrated phase is dispersed. |
