Surface-coated cubic boron nitride sintered material tool
The present invention is directed to a surface-coated cubic boron nitride sintered material tool including a cBN substrate and a hard coating layer formed on a surface of the cBN substrate and having an alternate laminated structure of A layer and B layer. A peak of the grain size distribution of cBN grains in the cBN sintered material is present within a range of a grain size from 0.50 to 1.00 μm. The A layer has a composition of (Ti 1-x Al x )N (0.4≤x≤0.7 in an atomic ratio). The B layer has a composition of (Cr 1-y-z Al y M z )N (0.03≤y≤0.6 and 0≤z≤0.05 in an atomic ratio). An X-ray diffraction peak of a (200) plane is present at a position of a diffraction angle of 43.6 plus or minus 0.1 degrees, and a plastic deformation work ratio of the B layer is 0.35 to 0.50.
1. A surface-coated cubic boron nitride sintered material tool comprising:
a tool body which is made of a cubic boron nitride sintered material; and
a hard coating layer formed on a surface of the tool body, the hard coating layer being made of an alternate laminated structure, in which at least one A layer and at least one B layer are alternately laminated, and having a total layer thickness of 0.5 to 4.0 μm,
wherein (a) the cubic boron nitride sintered material has a composition including:
10 to 50 vol % of one or more of TiC, TiN, and TiCN;
0.1 to 2 vol % of WC;
0.3 to 5 vol % of AN;
2 to 10 vol % of TiB 2 ;
1.5 to 10 vol % of Al 2 O 3 ; and
30 to 80 vol % of cBN (cubic boron nitride),
(b) when a grain size distribution of cBN grains in the cubic boron nitride sintered material is measured, a graph of the grain size distribution contains a single peak of the grain size distribution, said single peak being within a range of a grain size from 0.50 to 1.00 μm, and a value of a full width at half maximum of the single peak satisfies a range from 0.33 to 0.73 μm,
(c) the A layer is a Ti and Al complex nitride layer, which has an average single layer thickness of 0.1 to 3.0 μm and has an average composition satisfying 0.4≤x≤0.7 (x represents a content ratio of Al in terms of atomic ratio) in a case where the A layer is represented by a composition formula (Ti 1-x Al x )N,
(d) the B layer is a Cr, Al and M complex nitride layer, which has an average single layer thickness of 0.1 to 3.0 μm and has an average composition satisfying 0.03 ≤y≤0.6 and 0≤z≤0.05(y represents a content ratio of Al in terms of atomic ratio, z represents a total content ratio of the component M in terms of atomic ratio, and the component M represents one or more elements selected from group 4a elements excluding Cr, group5a elements, group 6a elements, B and Si in the periodic table) in a case where the B layer is represented by a composition formula (Cr 1-y-z Al y M z )N, and
(e) when an X-ray diffraction measurement is performed for the entirety of the hard coating layer constituted of the A layer and the B layer, an X-ray diffraction peak of a (200) plane is present at a position of a diffraction angle of 43.6 plus or minus 0.1 degrees, and a full width at half maximum of the diffraction peak satisfies 0.25 plus or minus 0.05 degrees.
2. The surface-coated cubic boron nitride sintered material tool according to claim 1 ,
wherein a value of a plastic deformation work ratio W plast /(W plast +W elast ) of the B layer, which is obtained by performing a nanoindentation test for the B layer with a load set to achieve an indentation depth of 1/10 times or smaller than a layer thickness, is within a range from 0.35 to 0.50.
3. The surface-coated cubic boron nitride sintered material tool according to claim 1 ,
wherein the A layer is formed immediately on the surface of the tool body and the B layer is formed as an outermost surface of the hard coating layer.
4. The surface-coated cubic boron nitride sintered material tool according to claim 1 ,
wherein the surface of the tool body has been subjected to bombardment treatment with argon ion prior to depositing the hard coating layer on the surface of the tool body.