To improve the defect resistance of a hard coating layer by including a specific wt.% of Co and/or Ni, and adjusting the hardness of each part of a thermet base, and the thickness of the hard coating layer of the surface after the sintering, within the specific ranges.
When a thermet base is sintered, a content of Co and/or Ni as a binder phase component, is adjusted to be 0.5-6.5 wt.%. The cooling atmosphere is 1-5 Torr nitrogen atmosphere in the sintering conditions. Whereby the thermet base after the sintering, has 1600-2000 Hv, and a cutting ridge part has the maximum hardness of 3000-3400 Hv. On the other hand, a surface hardened layer having 2200-2600 Hv of the maximum surface hardness, is formed on a flank and a cutting face. A hard coating layer of 1-20 μm of average layer thickness, is deposited on a surface of a titanium carbon nitride thermet base by physical evaporation method or chemical evaporation method. Whereby the hard coating layer is provided with the high defect resistance.
NAKAMURA SEIICHIRO
TSUJISAKI HISASHI
NONAKA KATSUHISA
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