| 摘要 |
Cemented carbide comprises a hard phase component comprising a tungsten carbide and at least one from carbides, nitrides or carbonitrides of metals of the groups IVa, Va or VIa in the periodic table; and a binder phase component comprising iron-group metal(s). A surface region of the cemented carbide has 90-99 % of the minimum hardness as compared with internal hardness. Independent claims are included for: (a) a method of manufacturing the cemented carbide comprising grinding and mixing the raw material powder comprising WC powder, powder(s) from the carbides, nitrides or carbonitrides as above, and material(s) of cobalt and nickel; molding the mixed powders; retaining a green body obtained for 0.3-2 hours at the first sintering temperature of 1350-1600 deg C in a non-oxidizing temperature; cooling to the second sintering temperature 20-200 deg C lower than the first sintering temperature; and retaining at the second sintering temperature in a vacuum for 1-3 hours; and (b) a surface coated cemented carbide, comprising the cemented carbide; and a hard coating formed on the surface of the cemented carbide. The cemented carbide comprises WC;, carbide, nitride or carbonitride of metallic element M that selects from metals of the groups IVa, Va and VIa of the periodic table, and a binder material of iron-group metal. The metallic element M contains zirconium and niobium. The first and second surface regions (5, 6) satisfy the relations: 0.1 <= q1suf/qin <= 0.9; 0.9 <= r1suf/rin <= 1.1; 1.1 <= q2suf/qin <= 1.5; 0.9 <= r2suf/rin <= 1.1; qin-M1suf/Tin; q1suf=M1suf/T1suf; q2suf-M2suf/T2suf; rin=Zrin/Tin; r1suf=Zr1suf/T1suf; and r2suf=Zr2suf/T2suf, are provided within a range of depth of 5-200 microns m from the surface of the cemented carbide, where Min is the content ratio of metallic element M in the inside of the cemented carbide; Zrin is the content ratio of zirconium in the inside of the cemented carbide; Tin is the content ratio of tungsten in the inside of the cemented carbide; M1suf is the content ratio of metallic element M in the first surface region of the cemented carbide; Zr1suf is the content ratio of zirconium in the first surface region of the cemented carbide; T1suf is the content ratio of tungsten in the first surface region of the cemented carbide; M2suf is the content ratio of metallic element M in the second surface region of the cemented carbide; Zr2suf is the content ratio of zirconium in the second surface region of the cemented carbide; and T2suf is the content ratio of tungsten in the second surface region of the cemented carbide. |
