CVD coated cutting tool
A coated cutting tool includes a substrate and a coating of one of more layers. The coating includes a layer of α-Al 2 O 3 of a thickness of 1-20 μm deposited by chemical vapour deposition (CVD). The α-Al 2 O 3 layer exhibits an X-ray diffraction pattern and wherein the texture coefficient TC(h k 1) is defined according to the Harris formula, wherein 1<TC(0 2 4)<4 and 3<TC(0 0 12)<6.
1. A coated cutting tool comprising:
a substrate; and
a coating, wherein the coating includes at least one layer of α-Al 2 O 3 with a thickness of 1-20 μm deposited by chemical vapour deposition (CVD), wherein said α-Al 2 O 3 layer exhibits an X-ray diffraction pattern, wherein a texture coefficient TC(h k l) is defined according to Harris formula
T
C
(
h
k
l
)
=
I
(
hk
l
)
I0
(
h
k
l
)
[
1
n
∑
i
=
0
n
I
(
hk
l
)
I0
(
h
k
l
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]
-
1
wherein the (h k l) reflections used are (1 0 4), (1 10), (1 13), (0 2 4), (1 1 6), (2 1 4), (300) and (0 0 12),
I(h k l)=measured intensity of the (h k l) reflection,
I 0 (h k l)=standard intensity according to ICDD's PDF-card No. 00-10-0173,
n=8,
wherein 1<TC(0 2 4)<4 and 3<TC(0 0 12)<6,
and wherein the sum of the TC(0 0 12) and TC(0 2 4) for said α-Al 2 O 3 layer is >6.5.
2. The coated cutting tool of claim 1 , wherein said α-Al 2 O 3 layer exhibits 1<TC(0 2 4)<3 and 3.5<TC(0 0 12)<5.5.
3. The coated cutting tool of claim 1 , wherein said α-Al 2 O 3 layer exhibits 1.5<TC(0 2 4)<2.5 and 4<TC(0 0 12)<5.
4. The coated cutting tool of claim 1 , wherein the third strongest TC(h k l) of said α-Al 2 O 3 layer is TC(1 1 0).
5. The coated cutting tool of claim 1 , wherein said α-Al 2 O 3 layer exhibits a {0 0 1} pole figure as measured by EBSD in a portion of the α-Al 2 O 3 layer parallel to the outer surface of the coating, wherein a pole plot based on the data of the pole figure, with a bin size of 0.25° over a tilt angle range of 0°≤β≤90° from a normal of an outer surface of the coating has a ratio of intensity within β<15° tilt angle to the intensity within 0°≤β≤90° of ≥40%, and wherein said α-Al 2 O 3 layer exhibits a {0 1 2} pole figure as measured by EBSD in a portion of the α-Al 2 O 3 layer parallel to the outer surface of the coating, wherein a pole plot based on the data of the pole figure, with a bin size of 0.25° over a tilt angle range of 0°≤β≤90° from the normal of the outer surface of the coating shows a ratio of intensity within β<15° tilt angle to the intensity within 0°<β<90° of >40%.
6. The coated cutting tool of claim 5 , wherein the {0 0 1} pole figure and the {0 1 2} pole figure are from a same portion of the α-Al 2 O 3 layer.
7. The coated cutting tool of claim 1 , wherein said α-Al 2 O 3 layer includes columnar grains.
8. The coated cutting tool of claim 1 , wherein the α-Al 2 O 3 layer includes columnar α-Al 2 O 3 layer grains and wherein an average width of said columnar grains is 0.5-2 μm as measured along a line parallel to a surface of the substrate in the middle of said α-Al 2 O 3 layer.
9. The coated cutting tool of claim 1 , wherein the thickness of the α-Al 2 O 3 layer is 2-10 μm.
10. The coated cutting tool of claim 1 , wherein the coating further includes a layer of one or more of TiN, TiCN, TiC, TiCO, TiCNO.
11. The coated cutting tool of claim 1 , wherein the coating includes layers in the following order from the surface of the substrate: TiN, TiCN, TiCNO and α-Al 2 O 3 .
12. The coated cutting tool of claim 1 , wherein the coating includes an outermost wear indication color layer.
13. The coated cutting tool of claim 1 , wherein the substrate is cemented carbide with a surface zone extending from the substrate surface to a depth of about 15-35 μm into the body, said surface zone being binder phase enriched and essentially free from cubic carbides.
14. The coated cutting tool of claim 1 , wherein the substrate is cemented carbide with a Co content of 6-12 wt %.
15. The coated cutting tool of claim 1 , wherein the cutting tool is a cutting insert and where an inscribed circle of said cutting insert has a diameter of ≥15 mm.