Coated cutting tool
A coated cutting tool having a substrate and a coating is provided. The coating includes an inner α-Al 2 O 3 -multilayer and an outer α-Al 2 O 3 -single-layer. The thickness of the inner α-Al 2 O 3 -multilayer is less than or equal to 35% of the sum of the thickness of the inner α-Al 2 O 3 -multilayer and the thickness of the outer α-Al 2 O 3 -single-layer. The sum of the thickness of the inner α-Al 2 O 3 -multilayer and the outer α-Al 2 O 3 -single-layer is 2-15 μm. The inner α-Al 2 O 3 -multilayer consists of alternating sublayers of α-Al 2 O 3 and sublayers of TiCO, TiCNO, AlTiCO or AlTiCNO. The inner α-Al 2 O 3 -multilayer can include at least 5 sublayers of α-Al 2 O 3 .
1. A coated cutting tool comprising:
a substrate; and
a coating, the coating including
an inner α-Al 2 O 3 -multilayer and an outer α-Al 2 O 3 -single-layer,
wherein a thickness of the outer α-Al 2 O 3 -single-layer is 1-10 μm,
wherein a thickness of the inner α-Al 2 O 3 -multilayer is less than or equal to 35% of a sum of the thickness of the inner α-Al 2 O 3 -multilayer and the thickness of the outer α-Al 2 O 3 -single-layer,
wherein the inner α-Al 2 O 3 -multilayer consists of alternating sublayers of α-Al 2 O 3 and sublayers of TiCO, TiCNO, AlTiCO or AlTiCNO, the inner α-Al 2 O 3 -multilayer including at least 5 sublayers of α-Al 2 O 3 , and
wherein the thickness of the inner α-Al 2 O 3 -multilayer is 12% to 35% of the sum of the thickness of the inner α-Al 2 O 3 -multilayer and the thickness of the outer α-Al 2 O 3 -single-layer.
2. The coated cutting tool according to claim 1 , wherein the inner α-Al 2 O 3 -multilayer is adjacent to the outer α-Al 2 O 3 -single-layer.
3. The coated cutting tool according to claim 1 , wherein the sum of the thickness of the inner α-Al 2 O 3 -multilayer and the outer α-Al 2 O 3 -single-layer is 2-16 μm.
4. The coated cutting tool according to claim 1 , wherein a period in the inner α-Al 2 O 3 -multilayer is 50-900 nm, wherein one period is a sum of a thickness of one sublayer of α-Al 2 O 3 and one sublayer of TiCO, TiCNO, AlTiCO or AlTiCNO.
5. The coated cutting tool according to claim 1 , wherein the inner α-Al 2 O 3 -multilayer in combination with the outer α-Al 2 O 3 -single-layer exhibits an XRD diffraction over a θ-2θ scan of 20°-140°, wherein an intensity of the 0 0 12 diffraction peak (peak area), I(0 0 12), to intensities of the 1 1 3 diffraction peak (peak area), I(1 1 3), the 1 1 6 diffraction peak (peak area), I(1 1 6), and the 0 2 4 diffraction peak (peak area), I(0 2 4), is 1(0 0 12)/I(1 1 3) >1, I(0 0 12)/I(1 1 6) >1 and I(0 0 12)/I(0 2 4) >1.
6. The coated cutting tool according to claim 5 , wherein an intensity of the 0 1 14 diffraction peak (peak area), I(0 1 14), to the intensity of the 0 0 12 diffraction peak (peak area), I(0 0 12), is I(0 1 14)/I(0 0 12)<2.
7. The coated cutting tool according to claim 5 , wherein a relation between the intensity of the 1 1 0 diffraction peak (peak area), I(1 1 0), and the intensities of the 1 1 3 diffraction peak (peak area), I(1 1 3), and the 0 2 4 diffraction peak (peak area), I(0 2 4), is I(110) >each of I(113) and I(024).
8. The coated cutting tool according to claim 5 , wherein a relation between the intensity of the 0 0 12 diffraction peak (peak area), I(0 0 12), and the intensity of the 1 1 0 diffraction peak (peak area), I(1 1 0), is I(0 0 12) >I(110).
9. The coated cutting tool according to claim 1 , further comprising at least one layer of TiC, TiN, TiAlN or TiCN located between the substrate and the inner α-Al 2 O 3 -multilayer.
10. The coated cutting tool according to claim 9 , wherein a thickness of the TiC, TiN, TiAlN or TiCN layer is 2-15 μm.
11. The coated cutting tool according to claim 9 , wherein the at least one layer of TiC, TiN, TiAlN or TiCN is a TiCN layer that exhibits an X-ray diffraction pattern, as measured using CuKα radiation and θ-2θ scan, wherein the TC(hkl) is defined according to Harris formula:
T
C
(
h
k
l
)
=
I
(
hkl
)
I
0
(
hkl
)
[
1
n
∑
n
=
1
n
I
(
hkl
)
I
0
(
hkl
)
]
-
1
where I(hkl) is the measured intensity (integrated area) of the (hkl) reflection, I 0 (hkl) is the standard intensity according to ICDD's PDF-card No. 42-1489, n is the number of reflections, reflections used in the calculation being (1 1 1), (2 0 0), (2 2 0), (3 1 1), (3 3 1), (4 2 0), (4 2 2) and (5 1 1), wherein TC(331)+TC(422)>5.
12. The coated cutting tool according to claim 1 , wherein the outermost layer of the coating is said outer α-Al 2 O 3 -single-layer.
13. The coated cutting tool according to claim 1 , wherein the substrate is selected from cemented carbide, cermet, ceramic, high speed steel and cBN.
14. The coated cutting tool according to claim 1 , wherein the substrate is cemented carbide including 3-14 wt % Co and more than 50 wt % WC.