Patent ID: 7939186

Claim:
A cutting tool made of a surface-coated cubic boron nitride-based ultra-high-pressure sintered material, comprising: a main body consisting of the ultra-high-pressure sintered material formed by ultra-high-pressure sintering of a compact having a composition of, in mass %, 13 to 30% of titanium nitride, 6.5 to 18% of aluminum and/or aluminum oxide and a balance of boron nitride, wherein under observation using a scanning electron microscope, the main body shows a texture such that an ultra-high-pressure sintering reaction product is present at the interface between a cubic boron nitride phase constituting a dispersed phase and a titanium nitride phase constituting a continuous phase; and a hard coating layer that has been vapor-deposited on the surface of the main body and has a lower layer of an average layer thickness in a range from 1.5 to 3 μm and an upper layer of an average layer thickness in a range from 0.3 to 3 μm, wherein: the lower layer of the hard coating layer consists of a vapor-deposited nitride of Ti, Al and Si having a composition of [Ti 1-X-Y Al X Si Y ]N, where X is in a range from 0.40 to 0.60 and Y is in a range from 0.02 to 0.10 in an atomic ratio; and the upper layer of the hard coating layer has been vapor-deposited on the surface of the lower layer, and consists of thin layers A consisting of a nitride of Ti, Al and Si having the composition of [Ti 1-X-Y Al X Si Y ]N, where X is in a range from 0.40 to 0.60 and Y is in a range from 0.02 to 0.10 in an atomic ratio, and thin layers B consisting of a Ti nitride (TiN), and has a structure in which the thin layer A and the thin layer B are layered alternately such that an average layer thickness of each single layer is in a range of 0.05 to 0.2 μm, and an average layer thickness of each single layer of the thin layer B is in a range of 0.05 to 0.15 μm.