Enhanced alumina layer produced by CVD
AssigneeSeco Tools AB
InventorSakari Ruppi
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Abstract
The present invention introduces a new and refined method to produce α-Al2O3 layers with substantially better wear resistance and toughness than the prior art. The α-Al2O3 layer of the present invention is formed on a bonding layer of (Ti,Al)(C,O,N) with increasing aluminium content towards the outer surface. Nucleation of α-Al2O3 is obtained through a nucleation step being composed of both aluminising and oxidisation steps. The α-Al2O3 layer according to this invention has a thickness ranging from 1 to 20 μm and is composed of columnar grains. The length/width ratio of the alumina grains is from 2 to 12, preferably 5 to 9. The layer is characterised by a strong (012) growth texture, measured using XRD, and by the almost total absence (104), (110), (113) and (116) diffraction peaks.
Claims33
A cutting tool insert comprising a substrate having a surface at least partially coated with a coating, the coating having a total thickness of about 10-40 μm, one or more refractory layers of which at least one layer is an alumina layer, the alumina layer comprising columnar α-Al2O3 grains with texture coefficients expressed as TC(hkl) of:
- TC(012) and TC(024) both 2.5-3.5, wherein the texture coefficient TC(hkl) is defined as:
- TC
-
- (
- hkl
- )
- =
- I
-
- (
- hkl
- )
- I
- 0
-
- (
- hkl
- )
-
- {
- 1
- n
-
- ∑
- I
-
- (
- hkl
- )
- I
- 0
-
- (
- hkl
- )
- }
- -
- 1
- where
- I(hkl)=measured intensity of the (hkl) reflection
- I0(hkl)=standard intensity according to JCPDS card no 46-1212
- n=number of reflections used in the calculation
- (hkl) reflections used are:
- (012), (104), (110), (113), (024), (116),
- wherein the coating comprises a first layer adjacent the substrate of CVD Ti(C,N), MTCVD Ti(C,N), or combinations thereof.
A cutting tool insert comprising a substrate having a surface at least partially coated with a coating, the coating having a total thickness of about 10-40 μm, one or more refractory layers of which at least one layer is an alumina layer, the alumina layer comprising columnar α-Al2O3 grains with texture coefficients expressed as TC(hkl) of TC(012) and TC(024) both 2.5-3.5,
- wherein the texture coefficient TC(hkl) is defined as:
- TC
-
- (
- hkl
- )
- =
- I
-
- (
- hkl
- )
- I
- 0
-
- (
- hkl
- )
-
- {
- 1
- n
-
- ∑
- I
-
- (
- hkl
- )
- I
- 0
-
- (
- hkl
- )
- }
- -
- 1
- where
- I(hkl)=measured intensity of the (hkl) reflection
- I0(hkl)=standard intensity according to JCPDS card no 46-1212
- n=number of reflections used in the calculation
- (hkl) reflections used are:
- (012), (104), (110), (113), (024), (116), and
- wherein the coating comprises a first layer adjacent the substrate of CVD TiN, CVD TiC, MTCVD Zr(C,N), MTCVD Ti(B,C,N), CVD HfN or combinations thereof, and a bonding layer including an Al concentration gradient deposited on the first layer.
Dependencies are inferred from the claim text.