SURFACE-COATED CUTTING TOOL
First Claim
1. A surface-coated cutting tool, comprising:
- a tool body that is made of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet; and
a hard coating layer that is deposited on a surface of the tool body,wherein the hard coating layer has a lower layer that is formed on the surface of the tool body and an upper layer that is formed on the lower layer,(a) the lower layer is made of a Ti compound layer, which has an average total layer thickness of 3 to 20 μ
m, and is composed of two or more of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer, the Ti compound layer including at least one TiCN layer,(b) the upper layer is made of an Al2O3 layer, which has an average layer thickness of 2 to 20 μ
m and has an α
-type crystal structure in a chemically deposited state,(c) regarding Al2O3 crystal grains of the entire upper layer, in a coincidence grain boundary distribution graph showing ratios of coincidence grain boundaries formed of the respective constituent atom-sharing lattice point type, to the whole coincidence grain boundary length in the range of Σ
3 to Σ
29, a highest peak is present in Σ
3 in the range of Σ
3 to Σ
29, and a distribution ratio of Σ
3 in the range of Σ
3 to Σ
29 is 70% or more, when electron beams are irradiated to the individual crystal grains in a measurement range of a polished cross-section by using a field-emission-type scanning electron microscope and an electron beam backward scattering diffraction device to measure an orientation of a normal line of each of crystal lattice planes having a corundum hexagonal crystal lattice, a crystal orientation relationship between the adjacent crystal lattices is calculated based on the measurement result, a distribution of lattice points (referred to as “
constituent atom-sharing lattice points”
) where each of constituent atoms of a crystal lattice interface shares one constituent atom between the crystal lattices is calculated, and distribution ratios of individuals of Σ
N+1 are calculated when Σ
N+1 represents the constituent atom-sharing lattice point type in which there are N lattice points sharing no constituent atoms between the constituent atom-sharing lattice points (here, N is any even number equal to or more than 2 in the corundum hexagonal close-packed crystal structure, but in a case where the upper limit of N is 28 from the viewpoint of distribution frequency, even numbers 4, 8, 14, 24, and 26 do not exist), and(d) a ratio of a grain boundary having a constituent atom-sharing lattice point type of Σ
3 continuing from an interface between the lower layer and the upper layer to an outermost surface of the upper layer is 60% or more of a grain boundary having a constituent atom-sharing lattice point type of Σ
3 distributed in the Al2O3 crystal grains of the entire upper layer.
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Accused Products
Abstract
In a surface-coated cutting tool, a hard coating layer composed of a lower layer and an upper layer is deposited on a surface of a tool body made of a WC-based cemented carbide or a TiCN-based cermet. The lower layer has at least one Ti compound layer made of a TiCN layer and the upper layer is made of an α-type Al2O3 layer. In a case where, regarding Al2O3 crystal grains of the entire upper layer, a constituent atom-sharing lattice point distribution is measured, a highest peak is present in Σ3, and a distribution ratio of Σ3 is 70% or more. A ratio of a Σ3-coincidence grain boundary continuing from an interface between the lower layer and the upper layer to an outermost surface of the upper layer is 60% or more of a Σ3-coincidence grain boundary of the upper layer.
3 Citations
8 Claims
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1. A surface-coated cutting tool, comprising:
-
a tool body that is made of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet; and a hard coating layer that is deposited on a surface of the tool body, wherein the hard coating layer has a lower layer that is formed on the surface of the tool body and an upper layer that is formed on the lower layer, (a) the lower layer is made of a Ti compound layer, which has an average total layer thickness of 3 to 20 μ
m, and is composed of two or more of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer, the Ti compound layer including at least one TiCN layer,(b) the upper layer is made of an Al2O3 layer, which has an average layer thickness of 2 to 20 μ
m and has an α
-type crystal structure in a chemically deposited state,(c) regarding Al2O3 crystal grains of the entire upper layer, in a coincidence grain boundary distribution graph showing ratios of coincidence grain boundaries formed of the respective constituent atom-sharing lattice point type, to the whole coincidence grain boundary length in the range of Σ
3 to Σ
29, a highest peak is present in Σ
3 in the range of Σ
3 to Σ
29, and a distribution ratio of Σ
3 in the range of Σ
3 to Σ
29 is 70% or more, when electron beams are irradiated to the individual crystal grains in a measurement range of a polished cross-section by using a field-emission-type scanning electron microscope and an electron beam backward scattering diffraction device to measure an orientation of a normal line of each of crystal lattice planes having a corundum hexagonal crystal lattice, a crystal orientation relationship between the adjacent crystal lattices is calculated based on the measurement result, a distribution of lattice points (referred to as “
constituent atom-sharing lattice points”
) where each of constituent atoms of a crystal lattice interface shares one constituent atom between the crystal lattices is calculated, and distribution ratios of individuals of Σ
N+1 are calculated when Σ
N+1 represents the constituent atom-sharing lattice point type in which there are N lattice points sharing no constituent atoms between the constituent atom-sharing lattice points (here, N is any even number equal to or more than 2 in the corundum hexagonal close-packed crystal structure, but in a case where the upper limit of N is 28 from the viewpoint of distribution frequency, even numbers 4, 8, 14, 24, and 26 do not exist), and(d) a ratio of a grain boundary having a constituent atom-sharing lattice point type of Σ
3 continuing from an interface between the lower layer and the upper layer to an outermost surface of the upper layer is 60% or more of a grain boundary having a constituent atom-sharing lattice point type of Σ
3 distributed in the Al2O3 crystal grains of the entire upper layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification