Coated cutting tool
A coated cutting tool comprising a substrate and a coating layer formed on a surface of the substrate, wherein: the coating layer comprises at least one α-type aluminum oxide layer; and, in the α-type aluminum oxide layer, when regarding a texture coefficient of a (0,0,6) plane as a TC18 (0,0,6), and also regarding a texture coefficient of a (0,0,12) plane as a TC18 (0,0,12), the TC18 (0,0,6) is the highest texture coefficient and the TC18 (0,0,12) is the second highest texture coefficient.
1. A coated cutting tool comprising a substrate and a coating layer formed on a surface of the substrate, wherein:
the coating layer comprises at least one α-type aluminum oxide layer; and
in the α-type aluminum oxide layer, when regarding a “texture coefficient of a (0,0,6) plane,” which is represented by formula (1) below, as being denoted as a “TC18 (0,0,6),” and also regarding a “texture coefficient of a (0,0,12) plane,” which is represented by formula (2) below, as being denoted as a “TC18 (0,0,12),” the TC18 (0,0,6) is the highest texture coefficient and the TC18 (0,0,12) is the second highest texture coefficient from among texture coefficients of eighteen crystal planes of the α-type aluminum oxide layer which are set forth below:
[
Equation
1
]
TC
18
(
0
,
0
,
6
)
=
I
(
0
,
0
,
6
)
I
0
(
0
,
0
,
6
)
{
1
18
Σ
I
(
h
,
k
,
l
)
I
0
(
h
,
k
,
l
)
}
-
1
[
Equation
2
]
(
1
)
TC
18
(
0
,
0
,
12
)
=
I
(
0
,
0
,
12
)
I
0
(
0
,
0
,
12
)
{
1
18
Σ
I
(
h
,
k
,
l
)
I
0
(
h
,
k
,
l
)
}
-
1
(
2
)
(In formulae (1) and (2), I (h,k,l) denotes a peak intensity for an (h,k,l) plane in X-ray diffraction of the α-type aluminum oxide layer, I 0 (h,k,l) denotes a standard diffraction intensity for an (h,k,l) plane which is indicated on JCPDS Card No. 10-0173 for α-type aluminum oxide, and (h,k,l) refers to the eighteen crystal planes of (0,1,2), (1,0,4), (1,1,0), (0,0,6), (1,1,3), (2,0,2), (0,2,4), (1,1,6), (0,1,8), (2,1,4), (3,0,0), (1,0,10), (0,2,10), (0,0,12), (0,1,14), (2,0,14), (1,1,15) and (1,0,16)).
2. The coated cutting tool according to claim 1 , wherein, in the α-type aluminum oxide layer, when regarding a texture coefficient of a (0,1,14) plane as a TC18 (0,1,14), as represented by formula (3) below, the TC18 (0,1,14) is the third highest texture coefficient from among the coefficients of the eighteen crystal planes of the α-type aluminum oxide layer:
[
Equation
3
]
TC
18
(
0
,
1
,
14
)
=
I
(
0
,
1
,
14
)
I
0
(
0
,
0
,
14
)
{
1
18
Σ
I
(
h
,
k
,
l
)
I
0
(
h
,
k
,
l
)
}
-
1
(
3
)
(In formula (3), I (h,k,l), I 0 (h,k,l) and (h,k,l) respectively refer to those set forth above with regard to formulae (1) and (2)).
3. The coated cutting tool according to claim 1 , wherein the TC18 (0,0,6) is from 7.50 or more to 14.00 or less.
4. The coated cutting tool according to claim 1 , wherein the TC18 (0,0,12) is from 2.00 or more to 5.00 or less.
5. The coated cutting tool according to claim 1 , wherein the TC18 (0,1,14) is from 0.80 or more to 2.50 or less.
6. The coated cutting tool according to claim 1 , wherein an average thickness of the α-type aluminum oxide layer is from 1.0 μm or more to 15 μm or less.
7. The coated cutting tool according to claim 1 , wherein the coating layer comprises, between the substrate and the α-type aluminum oxide layer, a Ti compound layer containing a Ti compound of a Ti element and an element of at least one kind selected from the group consisting of C, N, O and B.
8. The coated cutting tool according to claim 7 , wherein an average thickness of the Ti compound layer is from 2.0 μm or more to 20 μm or less.
9. The coated cutting tool according to claim 1 , wherein an average thickness of the coating layer is from 3.0 μm or more to 30 μm or less.
10. The coated cutting tool according to claim 1 , wherein the substrate is a cemented carbide, cermet, ceramic or a cubic boron nitride sintered body.
11. The coated cutting tool according to claim 2 , wherein the TC18 (0,0,6) is from 7.50 or more to 14.00 or less.
12. The coated cutting tool according to claim 11 , wherein the TC18 (0,0,12) is from 2.00 or more to 5.00 or less.
13. The coated cutting tool according to claim 11 , wherein the TC18 (0,1,14) is from 0.80 or more to 2.50 or less.
14. The coated cutting tool according to claim 2 , wherein the TC18 (0,0,12) is from 2.00 or more to 5.00 or less.
15. The coated cutting tool according to claim 3 , wherein the TC18 (0,0,12) is from 2.00 or more to 5.00 or less.
16. The coated cutting tool according to claim 2 , wherein the TC18 (0,1,14) is from 0.80 or more to 2.50 or less.
17. The coated cutting tool according to claim 3 , wherein the TC18 (0,1,14) is from 0.80 or more to 2.50 or less.
18. The coated cutting tool according to claim 4 , wherein the TC18 (0,1,14) is from 0.80 or more to 2.50 or less.
19. The coated cutting tool according to claim 2 , wherein an average thickness of the α-type aluminum oxide layer is from 1.0 μm or more to 15 μm or less.
20. The coated cutting tool according to claim 2 , wherein the coating layer comprises, between the substrate and the α-type aluminum oxide layer, a Ti compound layer containing a Ti compound of a Ti element and an element of at least one kind selected from the group consisting of C, N, O and B.