Alumina coated cutting tool

Patent metadata

Field	Value
Publication number	US-10286453-B2
Application number	US-201515115110-A
Country	US
Kind code	B2
Filing date	Jan 29, 2015
Priority date	Jan 30, 2014
Publication date	May 14, 2019
Grant date	May 14, 2019

Abstract

A coated cutting tool insert includes a substrate of cemented carbide, cermet, ceramics, steel or cubic boron nitride having deposited thereon a coating having a total thickness of 60 μm, including one or more layers having a wear resistant layer of α-Al2O3 of a thickness of 1 to 45 μm deposited by chemical vapour deposition (CVD). The α-Al2O3 layer includes at least two portions, a first thickness portion and a second thickness portion immediately on top of the first thickness portion. The first thickness portion has an essentially columnar α-Al2O3 grain structure, and at a transition from the first thickness portion to the second thickness portion the grain boundaries of at least 1 out of 25 neighboring grains of the α-Al2O3 grains undergo a directional change into a direction that is essentially perpendicular, 90±45 degrees, to the grain boundaries in the first thickness portion.

First claim

The invention claimed is:

1. A coated cutting tool insert comprising:
a substrate comprising cemented carbide, cermet, ceramics, steel or cubic boron nitride having deposited thereon a coating of a total thickness of a maximum of 60 μm with one or more layers including a wear resistant layer of α-Al 2 O 3 of a thickness of 1 to 45 μm deposited by chemical vapour deposition (CVD), wherein when observed in a SEM microphotograph of a cross section of the α-Al 2 O 3 layer, the α-Al 2 O 3 layer including at least two portions, a first thickness portion and a second thickness portion disposed immediately on the first thickness portion, the first thickness portion having an essentially columnar α-Al 2 O 3 grain structure and grain boundaries, and at a transition of α-Al 2 O 3 crystalline grains from the first thickness portion to the second thickness portion grain boundaries of at least 1 out of 25 neighbouring grains of the transition α-Al 2 O 3 grains undergo a directional change into a direction that is essentially perpendicular to the grain boundaries of the first thickness portion, the directional change being 90±45 degrees.

2. The coated cutting tool insert of claim 1 , wherein the α-Al 2 O 3 layer, at least in the first thickness portion, has a preferred growth orientation of the α-Al 2 O 3 grains along a <0 0 1> crystallographic direction or perpendicular to the {0 1 2} or {1 0 4} or {0 1 0} crystallographic plane.

3. A coated cutting tool insert according to claim 1 , wherein at least 70% of the α-Al 2 O 3 grains extending to an outer surface of the α-Al 2 O 3 layer are terminated by facets perpendicular to an axis within 0 to 35 degrees, to a normal of the substrate surface.

4. The coated cutting tool insert of claim 3 , wherein the facets terminating the α-Al 2 O 3 crystals are {0 0 1} crystallographic planes.

5. The coated cutting tool insert of claim 3 , wherein the outer surface of the α-Al 2 O 3 layer has surface roughness characteristics selected from:
i) a surface roughness Ra from 0.05 to 0.2 μm, when the layer of α-Al 2 O 3 has a thickness of 8 μm or more; and
ii) a surface roughness Ra from 0.03 to 0.2 μm, when the layer of α-Al 2 O 3 has a thickness of less than 8 μm, whereby the surface roughness is measured on the α-Al 2 O 3 layer in an as-deposited state without top layers and without any post-treatment.

6. The coated cutting tool insert of claim 1 , wherein an overall fiber texture of the entire α-Al 2 O 3 layer is characterized by a texture coefficient TC (0 0 12)>3, the TC (0 0 12) being defined as follows:

TC
⁡

(
0012
)

=

I
⁡

(
0012
)

I
0

⁡

(
0012
)

⁡

[

1
n

⁢

∑

n
-
1

n

⁢

I
⁡

(
hkl
)

I
0

⁡

(
hkl
)

]

-
1

,

wherein
(h k l)=measured intensity of the (hkl) reflection
I 0 (h k l)=standard intensity of the standard powder diffraction data according to JCPDF-card no. 42-1468
n=number of reflections used in the calculation, whereby the (hkl) reflections used are: (0 1 2), (1 0 4), (1 10), (1 1 3), (1 1 6), (3 0 0) and (0 0 12).

7. The coated cutting tool insert of claim 1 , wherein the coating comprises a top coating includes a top coating having a thickness between 0.05 to 3 μm, deposited by CVD or PVD, on top of the α-Al 2 O 3 layer, the top coating including one or more layers selected from the group of TiN, TiC, TiCN, ZrN, ZrCN, HfN, HfCN, VC, TiAlN, TiAlCN and AlN, or multilayers thereof, wherein the coating includes one or more refractory layers on the substrate and underneath the α-Al 2 O 3 layer, wherein the one or more refractory layers comprise carbide, nitride, carbonitride, oxycarbonitride or boroncarbonitride of one or more metals selected from the group consisting of Ti, Al, Zr, V and Hf, or combinations thereof, being deposited by chemical vapour deposition (CVD) or moderate temperature chemical vapour deposition (MT-CVD) and each refractory layer having a thickness of from 0.5 to 20 μm, wherein a first refractory layer immediately on top and in contact with the substrate surface is selected from the group consisting of Ti(C,N), TiN, TiC, Ti(B,C,N), HfN, and Zr(C,N), or combinations thereof.

8. The coated cutting tool insert of claim 7 , wherein the first refractory layer adjacent to the substrate surface is Ti(C,N), a refractory layer immediately underneath and in contact with α-Al 2 O 3 layer being cubic (Ti,Al)N, cubic (Ti,Al)(C,N,), or of a multilayer structure of alternating cubic (Ti,Al)N or cubic (Ti,Al)(C,N) layers and one or more refractory layers of carbide, nitride, carbonitride, oxycarbonitride or boroncarbonitride of one or more of Ti, Zr, V and Hf, or combinations thereof.

9. The coated cutting tool insert of claim 1 , wherein the substrate includes cemented carbide of 4 to 12 wt-% Co, 0.3-10 wt-% cubic carbides, nitrides or carbonitrides of the metals from groups IVb, Vb and VIb of the periodic table, and balance WC.

10. The coated cutting tool insert of claim 1 , wherein the substrate consists of cemented carbide comprising a binder phase enriched surface zone having a thickness of 5 to 30 μm from the substrate surface, the binder phase enriched surface zone having a Co content that is at least 1.5 times higher than in a core of the substrate and having a content of cubic carbides that is less than 0.5 times the content of cubic carbi

Assignees

• Sandvik Intellectual Property
• Sandvik Intellectual Property

Inventors

• Ruppi Sakari
• Engstrom Hindrik
• Lauridsen Jonas
• Alm Oscar
• Matsson Peter
• Larsson Tommy
• Lindahl Erik
• Engqvist Jan
• Stiens Dirk

Classifications

• B23B27/148 Primary

  Composition of the cutting inserts · CPC title

• B23B2224/04

  Aluminium oxide · CPC title

• C30B29/20

  Aluminium oxides · CPC title

• C23C16/403 Primary

  of aluminium, magnesium or beryllium · CPC title

• C30B29/68

  Crystals with laminate structure, e.g. "superlattices" · CPC title