FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. ALN-BASED HARD MATERIAL LAYER ON BODIES OF METAL, HARD
METAL, CERMET OR CERAMICS, AND METHOD FOR THE PRODUCTION
THEREOF
2.
1. (A) FRAUNHOFER-GESELLSCHAFT ZUR FÖRDERUNG DER
ANGEWANDTEN FORSCHUNG E.V.
(B) Germany
(C) Hansastr. 27c 80686 München GERMANY
The following specification particularly describes the invention and the manner in which
it is to be performed.

2
Description
The present invention relates to the technical field of materials technology
and relates to an AlN-based hardcoat layer on bodies made of metal,
cemented carbide, cermet or ceramic, and to a process for production
thereof. The AlN-based hardcoat layer of the invention is highly textured
and oxygen-doped and may be used, for example, as antiwear layers for
cutting tools, as protective layers for turbine blades or as diffusion barriers
in microelectronics.
The prior art discloses AlON layers that are used predominantly as
dielectric layers and for resistive memory in microelectronics. The layers
are produced here by a wide variety of different CVD (thermal CVD, RTPMOCVD) and PVD methods.
JP 2001 287 104 A1 discloses a coating composed of one or more layers
containing aluminum oxynitride. Each of the aluminum oxynitride layers
consists of a solid Al-O-N solution, a crystalline Al-O-N compound or a
mixture of the two. In addition, AIN may be mixed therewith.
DE 10 2010 052 687 A1 discloses a multilayer oxynitride layer system
comprising cubic AIN and AION on substrates such as preferably HSS
and cemented carbide. What is disclosed here is a layer structure
consisting of multiple layers, including an oxynitride layer, preferably
composed of the elements Cr, AI, O and N with a layer thickness between
0.3 and 2.5 micrometers.
US 4 336 305 A1 discloses a ceramic indexable cutting insert, on the
surface of which has been disposed a thin coating of at least one layer of
Al2O3 or AlON by CVD methods.
3
WO 2012 126 031 A1 discloses a combination of a TiAlN layer with a
second layer consisting of AlON and optionally carbon, where Al may be
partly replaced by another metal.
A disadvantage of the solutions known from the prior art is that the
hardness and wear resistance of the AlN hardcoat layers produced are
inadequate. AlN-based hardcoat layers according to the prior art show a
hardness of around 2000 HV. A further disadvantage is that the production
of such AlN-based hardcoat layers is time-consuming and costly.
The problem addressed is that of providing an AlN hardcoat layer having
improved hardness and wear resistance. Another problem addressed by
the invention is that of providing a time- and cost-efficient thermal CVD
process for producing AlN hardcoat layers.
The problems are solved by the features of the claims, and the invention
also includes combinations of the individual dependent claims in the sense
of an AND linkage, provided that they are not mutually exclusive.
The problem is solved in accordance with the invention by an AlN-based
hardcoat layer on bodies made of metal, cemented carbide, cermet or
ceramic, which is an individual layer produced by CVD methods without
plasma excitation or a multilayer system, wherein at least the one layer or
at least one layer of the multilayer system is an AlN-based hardcoat layer
with hexagonal lattice structure having a <002> texture which is oxygendoped, where the oxygen doping is within a range from 0.01 at% to 15 at%
without direct lattice binding in the hexagonal structure.
Advantageously, the texture has a texture coefficient TC of > 2.5 to 8.
Also advantageously, the texture is in columnar form.
4
Advantageously, the AlN-based hexagonal hardcoat layer has a proportion
of Al content of ≥ 45 at%.
Further advantageously, the h-AlN-based hardcoat layer has a layer
thickness between 5 and 40 µm.
In an advantageous configuration of the invention, at least one h-AlNbased hardcoat layer is in nanocrystalline form, where the crystallite size
is particularly advantageously 5 nm to 100 nm.
In addition, particularly advantageously, the nanocrystalline h-AlN-based
hardcoat layer may have amorphous components, where there is very
particularly advantageously oxygen doping of 0.01 at% to 25 at%.
Advantageously, at least one h-AlN-based hardcoat layer has a hardness
of 2500 HV [0.01] to 2800 HV [0.01].
In addition, it may advantageously be the case that the h-AlN-based
hardcoat layer has doping by Zr, Si, Hf, Ta and/or Ti.
In an advantageous configuration, there is at least one tie layer, interlayer
and/or outer layer, which particularly advantageously consist(s) of nitrides,
carbides, carbonitrides, oxycarbides, oxycarbonitrides of the elements of
transition groups 4-6 of the PTE or of oxides of Al or Zr. Very particularly
advantageously, the tie layer, interlayer and/or outer layer is TiN, TiCN,
TiAlN and/or combinations thereof.
The invention also provides a process for producing a AlN-based hardcoat
layer on bodies made of metal, cemented carbide, cermet or ceramic, in
which a textured, oxygen-doped h-AlN-based hardcoat layer is deposited
by means of a thermal CVD method without plasma excitation in a CVD
5
reactor from a gas phase composed of AlCl3, H2, N2, NH3, CO and/or CO2
and at temperatures between 850°C and 1050°C and at pressures
between 0.1 kPa and 30 kPa, with supply of CO and/or CO2 separately to
the CVD reactor via a separate gas supply.
Advantageously, NH3 is supplied separately to the CVD reactor for
production of the gas phase, and a gas phase comprising 0.2% by volume
to 2% by volume of CO and/or CO2 is particularly advantageously
deposited.
Likewise advantageously, an AlN-based hardcoat layer is deposited from
a gas phase with 0.30% by volume to 2% by volume of NH3.
In an advantageous configuration of the process, the deposition of the hAlN-based hardcoat layer is preceded by deposition of at least one tie
layer, interlayer and/or outer layer composed of nitrides, carbides,
carbonitrides, oxycarbides, oxycarbonitrides of the elements of transition
groups 4-6 of the PTE or of oxides of Al or Zr, which is very particularly
advantageously deposited as a tie layer, interlayer and/or outer layer
comprising TiN, TiCN, TiAlN and/or combinations thereof.
The invention provides an oxygen-doped, textured h-AlN-based hardcoat
layer that has been produced in a time- and cost-efficient manner by a
thermal CVD process without plasma excitation and has improved
hardness and wear resistance.
The invention provides pure AlN-based hardcoat layers that always have a
texture of a hexagonal lattice structure formed in <002> direction. In order
to obtain the hexagonal lattice structure of the AlN hardcoat layer, it is
proposed that CO and/or CO2 be introduced into the CVD coating
chamber selectively and separately via separate gas feeds specifically by
6
a CVD method without plasma excitation, in order thus to dope oxygen
into the hexagonal lattice structure and incorporate it there selectively.
Direct lattice binding of the oxygen does not take place here. Contrary to
the prior art, the h-AlN-based hardcoat layer thus does not have oxygen
contents attributable to impurities and leaks in the CVD reactor, but rather
controlled oxygen doping that influences the morphological properties
without direct lattice binding exclusively at interstitial lattice sites.
As a result, a novel highly textured, oxygen-doped h-AlN hardcoat layer is
provided, which has a high hardness of up to 2800 HV [0.01] and high
wear resistance. Surprisingly, the selective incorporation of a specific
proportion of oxygen in the deposition of the layer has a positive effect on
the structure and properties of the h-AlN-based hardcoat layer of the
invention.
This is achieved in that the AlN-based hardcoat layer with hexagonal
lattice structure is provided and produced, which has a texture and
contains oxygen doping in the range from 0.01 at% to 15 at%, and hence
has high hardness and excellent wear resistance.
A texture in the context of the invention shall be understood to mean a
crystallographic orientation of the crystallites of the oxygen-doped h-AlNbased hardcoat layer which has grown on the substrate by virtue of the
CVD method of the invention without plasma excitation. This texture is
advantageously in columnar form, with each column having essentially
hexagonal and hence honeycomb-like form.
The columnar formation of the texture of the oxygen-doped, highly
textured h-AlN-based hardcoat layer creates intrinsic stresses by virtue of
the direct contact of the adjacent columns within the AlN-based hardcoat
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layer of the invention, which lead to tension in the hardcoat layer and
hence to a significant improvement in hardness and wear resistance.
According to the invention, at least one layer of an oxygen-doped AlNbased layer system has a hexagonal lattice structure having a <002>
texture.

The inventive texture of the individual layer(s) can be expressed by a
texture coefficient TC.
This texture coefficient TC is calculated by the following formula according
to JCPDS 0-25-1133:
𝑇𝐶(௛௞௟) =
𝐼(௛௞௟)/𝐼଴(௛௞௟)
1
𝑛
∑ 𝐼(௛௞ )/𝐼଴(௛௞௟)
The following 8 lattice planes are used for the calculation: <100>, <002>,
<101>, <102>, <110>, <103>, <200>, <112>.
The TC of the oxygen-doped h-AlN-based hardcoat layer that has been
highly textured in accordance with the invention is advantageously > 2.5 to
8.
The solution of the invention provides a novel oxygen-doped h-AlN-based
hardcoat layer on bodies made of metal, cemented carbide, cermet or
ceramic, wherein the h-AlN-based hardcoat layer is a single layer or a
multilayer system.
In a multilayer system, at least one h-AlN-based hardcoat layer of the
layer system may be in nanocrystalline form. The nanocrystalline layer is
in particularly fine-grain form and has a crystallite size of 5 nm to 100 nm.
Such a nanocrystalline AlN-based hardcoat layer may additionally have
8
amorphous components and advantageously oxygen doping of 0.01 at%
to 25 at%.
It is particularly advantageous when there are one or more tie layers,
interlayers and/or outer layers between the body to be coated and oxygendoped h-AlN-based hardcoat layer of the invention. The prior deposition of
one or more tie layers, interlayers and/or outer layers can especially
achieve significantly better adhesion of the oxygen-doped h-AlN-based
hardcoat layer of the invention on the body made of metal, cemented
carbide, cermet or ceramic.
The deposition of one or more interlayers between the tie layer and outer
layer achieves improved hardness of the overall layer system and
especially of the tie layer.
The applying of one or more outer layers enables a further increase in
oxidation resistance and improved binding of the h-AlN-based hardcoat
layer subsequently disposed thereon. This additionally achieves the effect
that friction between the highly textured, oxygen-doped h-AlN-based
hardcoat layer and the material to be processed is reduced, which
achieves, for example, a significantly improved service life of the antiwear
layer. Advantageously, the tie layers, interlayers or outer layers consist of
nitrides, carbides, carbonitrides, oxycarbides, oxycarbonitrides of the
elements of transition groups 4-6 of the PTE or of oxides of Al or Zr.
Particularly advantageously, the tie layers, interlayers and/or outer layers
may be composed of TiN, TiCN, TiAlN and/or combinations thereof. For
good adhesion on the body to be coated, for example, the tie layer may
consist of TiN. For improvement of the hardness, there may be an
interlayer, for example composed of TiCN, which is deposited atop the tie
layer. In addition, for further improvement in the adhesion of the h-AlN-
9
based hardcoat layer of the invention, an additional outer layer of TiN may
be provided atop the interlayer.

The inventive hexagonal lattice structure of the AlN-based hardcoat layer
and the controlled use of CO and/or CO2 as additional oxygen source in
the CVD coating apparatus in combination with the texture of the invention
achieves particularly high hardness values of 2500 HV [0.01] to 2800 HV
[0.01] with high element contents of Al of ≥ 45 at%. A maximum element
content of Al increases oxidation resistance and hence has positive effect
on wear resistance, especially at high temperatures.
It is advantageous when the h-AlN-based hardcoat layer has additional
doping by Zr, Si, Hf, Ta and/or Ti. The introduction of small amounts of Zr,
Si, Hf, Ta and/or Ti introduces extrinsic atoms into the hexagonal lattice
structure and hence improves the hardness and wear resistance of the hAlN-based hardcoat layer.

The improved wear properties of the h-AlN-based hardcoat layer of the
invention with texture and oxygen doping are achieved by a thermal CVD
method without plasma excitation, in that this layer is deposited in a CVD
reactor a gas phase composed of AlCl3, H2, N2 and NH3 with selective
addition of CO and/or CO2, at temperatures between 850°C and 1050°C
and at pressures between 0.1 kPa and 30 kPa.
It has been found to be advantageous when the reactive gas phase
required for the coating is mixed only within the CVD reactor, where it is
deposited directly on the substrate.
For provision of the gas phase in the CVD reactor, it is advantageous
when NH3 is conducted into the reactor chamber via separate gas supply
devices.
10
The separate supply of the constituents of the gas phase has the
advantage that the gas phase at the moment of deposition in the reactor
has significantly higher reactivity, and hence the risk of premature reaction
in the gas supply device is reduced. Moreover, the separate supply of the
reaction gases to the CVD reactor can adjust the composition of the gas
phase individually and in a simple manner and especially control the
supply of NH3, CO2 and/or CO.
It has likewise been found to be advantageous when a gas phase with
0.2% by volume to 2.0% by volume of CO and/or CO2 is deposited. The
selective addition of CO and/or CO2 leads to specific intercalation of
oxygen into the AlN-based hardcoat layer without direct lattice binding into
the hexagonal lattice structure. This especially leads to improved oxidation
resistance of the h-AlN-based hardcoat layer. Advantageously, the gas
phase may additionally have doping by Zr, Si, Hf, Ta and/or Ti, which are
incorporated into the hexagonal lattice structure of the h-AlN-based
hardcoat layer during the deposition of the hardcoat layer.
It has been found that, surprisingly, significant texturing with a high texture
coefficient TC of > 2.5 to 8 is achieved when the gas phase to be
deposited has a proportion of NH3 of 0.3% by volume to 2.0% by volume.

In the composition of the invention, a novel highly textured, oxygen-doped
h-AlN-based hardcoat layer is provided, which has a high hardness up to
2800 HV [0.01] and high wear resistance. Surprisingly, the selective
incorporation of a specific proportion of oxygen in the deposition of the
layer has a positive effect on the structure and properties of the h-AlNbased hardcoat layer of the invention. The novel LPCVD process permits
the production of the layers in the temperature range of 850°C - 1050°C.
11
The invention is elucidated in detail below by multiple working examples
and the corresponding figures. The figures show:
Fig. 1: x-ray diffractogram of the highly textured, oxygen-doped h-AlN
layer produced by CVD according to Example 1,
Fig. 2: TEM image of the highly textured, oxygen-doped h-AlN-based
hardcoat layer according to Example 1
Fig. 3: TEM-EDX analysis of the highly textured, oxygen-doped h-AlNbased hardcoat layer according to Example 1
Fig. 4: x-ray diffractogram of the highly textured, oxygen-doped h-AlNbased hardcoat layer Example 2 produced by CVD
Fig. 5: TEM image of the highly textured, oxygen-doped h-AlN-based
hardcoat layer according to Example 2
Fig. 6: TEM-EDX analysis of the highly textured, oxygen-doped h-AlNbased hardcoat layer according to Example 2
Fig. 7: SEM polished section image of a 40 µm-thick highly textured,
oxygen-doped h-AlN-based hardcoat layer according to Example 3
Fig. 8: EDX analysis of the highly textured, oxygen-doped h-AlN-based
hardcoat layer, doped with silicon, produced by CVD according to
Example 4
Fig. 9: EDX analysis of the highly textured, oxygen-doped h-AlN-based
hardcoat layer, doped with zirconium, produced by CVD according
to Example 5
Fig. 10: wear test on a highly textured, oxygen-doped h-AlN-based
hardcoat layer according to Example 1, 4 and 5
Example 1
A highly textured and oxygen-doped h-AlN-based hardcoat layer is
deposited by a thermal CVD method without plasma excitation as outer
layer on WC/Co cemented carbide indexable cutting inserts that have
12
been precoated with a 5 µm-thick TiN/TiCN/TiN layer system as tie layer,
interlayer and outer layer. The coating process is conducted in a hot-wall
CVD reactor having an internal diameter of 75 mm. The CVD coating is
effected with a gas phase composed of 0.46% by volume of AlCl3, 0.31%
by volume of NH3, 0.72% by volume of CO2, 4.80% by volume of N2 and
93.71% by volume of H2. The deposition temperature is 900°C and the
process pressure is 6 kPa. After a coating time of 90 min, a 5.2 µm-thick
highly textured and oxygen-doped h-AlN-based hardcoat layer is obtained.
In the x-ray crystallography layer analysis conducted, an h-AlN phase is
detected, the crystallites of which have grown in highly textured manner in
<002> direction. The texture coefficient TC is 7.2. TEM analyses
combined with an elemental analysis according to Fig. 2 and Fig. 3
showed that the h-AlN phase is doped with 13 at% of oxygen. By means
of a Vickers indenter, a microhardness of 2690 HV [0.01] was measured.
The elemental analysis in the TEM gave the following element contents:
47 at% Al,
39.5 at% N,
13 at% O,
and 0.5 at% Cl.
Example 2
A highly textured and oxygen-doped h-AlN-based hardcoat layer, which is
nanocrystalline with amorphous components, is deposited by a thermal
CVD method as outer layer on WC/Co cemented carbide indexable cutting
inserts that have been precoated with a 5 µm-thick TiN/TiCN/TiN layer
system as tie layer, interlayer and outer layer. The coating process is
conducted in a hot-wall CVD reactor having an internal diameter of 75
mm. The CVD coating is effected with a gas phase composed of 0.46% by
13
volume of AlCl3, 0.42% by volume of NH3, 0.61% by volume of CO2,
4.68% by volume of N2 and 93.83% by volume of H2. The deposition
temperature is 850°C and the process pressure is 6 kPa. After a coating
time of 90 min, a 6.0 µm-thick highly textured and oxygen-doped h-AlNbased hardcoat layer is obtained, which is in nanocrystalline form with
amorphous components.
In the x-ray crystallography layer analysis conducted, by means of the xray diffractogram according to Figure 4, an h-AlN phase is detected, the
crystallites of which have grown in highly textured manner in <002>
direction. The texture coefficient TC is 4.2. TEM analyses combined with
an elemental analysis according to Fig. 5 and Fig. 6 showed that the h-AlN
phase has been doped with 24 at% of oxygen. By means of a Vickers
indenter, a microhardness of 2580 HV [0.01] was measured.
The elemental analysis in the TEM gave the following element contents:
45 at% Al,
30.5 at% N,
24 at% O,
and 0.5 at% Cl.
Example 3
A highly textured, oxygen-doped h-AlN-based hardcoat layer is deposited
by a thermal CVD method as outer layer on WC/Co cemented carbide
indexable cutting inserts that have been precoated with a 1 µm-thick TiN
tie layer. The coating process is conducted in a hot-wall CVD reactor
having an internal diameter of 75 mm. The CVD coating is effected with a
gas phase composed of 0.46% by volume of AlCl3, 0.45% by volume of
NH3, 0.58% by volume of CO2, 4.80% by volume of N2 and 93.71% by
volume of H2. The deposition temperature is 1000°C and the process
14
pressure is 6 kPa. After a coating time of 150 min, a 40.0 µm-thick highly
textured and oxygen-doped h-AlN-based hardcoat layer is obtained.
In the x-ray crystallography layer analysis conducted, an h-AlN phase is
detected, the crystallites of which have grown in highly textured manner in
<002> direction. The texture coefficient TC is 5.4. The SEM analysis of the
polished section according to Fig. 7 shows a 40 µm-thick highly textured hAlN-based hardcoat layer. By means of a Vickers indenter, a
microhardness of 2760 HV [0.01] was measured.
Example 4
A highly textured and oxygen-doped h-AlN-based hardcoat layer doped
with silicon is deposited by a thermal CVD method as outer layer on
WC/Co cemented carbide indexable cutting inserts that have been
precoated with a 5 µm-thick TiN/TiCN/TiN layer system as tie layer,
interlayer and/or outer layer. The coating process is conducted in a hotwall CVD reactor having an internal diameter of 75 mm. The CVD coating
is effected with a gas phase composed of 0.46% by volume of AlCl3,
0.06% by volume SiCl4, 0.31% by volume of NH3, 0.72% by volume of
CO2, 4.80% by volume of N2 and 93.65% by volume of H2. The deposition
temperature is 900°C and the process pressure is 6 kPa. After a coating
time of 90 min, a 4.8 µm-thick highly textured and oxygen-doped h-AlNbased hardcoat layer doped with silicon is obtained.
In the x-ray crystallography layer analysis conducted, an h-AlN phase is
detected, the crystallites of which have grown in highly textured manner in
<002> direction. The texture coefficient TC is 3.7. According to Figure 8,
the EDX analysis of the polished section shows doping of the highly
textured h-AlN layer with oxygen and silicon. By means of a Vickers
indenter, a microhardness of 2610 HV [0.01] was measured.
15
Example 5
A highly textured and oxygen-doped h-AlN-based hardcoat layer doped
with zirconium is deposited by a thermal CVD method as outer layer on
WC/Co cemented carbide indexable cutting inserts that have been
precoated with a 5 µm-thick TiN/TiCN/TiN layer system as tie layer,
interlayer and outer layer. The coating process is conducted in a hot-wall
CVD reactor having an internal diameter of 75 mm. The CVD coating is
effected with a gas phase composed of 0.46% by volume of AlCl3, 0.04%
by volume ZrCl4, 0.31% by volume of NH3, 0.72% by volume of CO2,
4.80% by volume of N2 and 93.67% by volume of H2. The deposition
temperature is 1030°C and the process pressure is 6 kPa. After a coating
time of 90 min, a 4.5 µm-thick highly textured and oxygen-doped h-AlNbased hardcoat layer doped with zirconium is obtained.
In the x-ray crystallography layer analysis conducted, an h-AlN phase is
detected, the crystallites of which have grown in highly textured manner in
<002> direction. The texture coefficient TC is 4.1. According to Figure 9,
the EDX analysis of the polished section shows doping of the highly
textured h-AlN-based hardcoat layer with oxygen and zirconium. By
means of a Vickers indenter, a microhardness of 2650 HV [0.01] was
measured.

We Claim:-
1. An AlN-based hardcoat layer on bodies made of metal, cemented
carbide, cermet or ceramic, which is an individual layer produced by
CVD methods without plasma excitation or a multilayer system,
wherein at least the one layer or at least one layer of the multilayer
system is an AlN layer with hexagonal lattice structure having a
<002> texture which is oxygen-doped, where the oxygen doping is
within a range from 0.01 at% to 15 at% without direct lattice binding
in the hexagonal lattice structure.
2. The hardcoat layer as claimed in claim 1, in which the texture has a
texture coefficient TC of > 2.5 to 8.
3. The hardcoat layer as claimed in at least one of the preceding
claims, in which the Al content is ≥ 45 at%.
4. The hardcoat layer as claimed in at least one of the preceding
claims, in which the texture is in columnar form.
5. The hardcoat layer as claimed in at least one of the preceding
claims, in which the h-AlN-based hardcoat layer has a layer
thickness between 5 and 40 µm.
6. The hardcoat layer as claimed in at least one of the preceding
claims, in which the at least one h-AlN-based hardcoat layer is
nanocrystalline.
7. The hardcoat layer as claimed in claim 6, in which the crystallite
size is 5 nm to 100 nm.
17
8. The hardcoat layer as claimed in claim 6, in which the
nanocrystalline h-AlN-based hardcoat layer has amorphous
components.
9. The hardcoat layer as claimed in claim 8, in which there is oxygen
doping of 0.01 at% to 25 at%.
10. The hardcoat layer as claimed in at least one of the preceding
claims, in which the h-AlN-based hardcoat layer has doping by Zr,
Si, Hf, Ta and/or Ti.
11. The hardcoat layer as claimed in at least one of the preceding
claims, in which at least one h-AlN-based hardcoat layer has a
hardness of 2500 HV [0.01] to 2800 HV [0.01].
12. The hardcoat layer as claimed in at least one of the preceding
claims, in which there is at least one tie layer, interlayer and/or
outer layer.
13. The hardcoat layer as claimed in claim 12, in which the tie layer,
interlayer and/or outer layer consist(s) of nitrides, carbides,
carbonitrides, oxycarbides, oxycarbonitrides of the elements of
transition groups 4-6 of the PTE or of oxides of Al or Zr.
14. The hardcoat layer as claimed in claim 12 or 13, in which the tie
layer, interlayer and/or outer layer is TiN, TiCN, TiAlN and/or
combinations thereof
15. A method for producing an AIN-based hard material layer on bodies of metal, hard metal, cermet or ceramic, in which, by means of a thermal CVD method without plasma excitation in a CVD reactor, a textured, oxygen-doped h-AlN-based hard material layer is deposited from a gas phase of AlC, H2, N2, NH3 , CO and/or CO2 and at temperatures between 850°C and 1050°C and at pressures between 0.1 kPa and 30 kPa, wherein CO and/or CO2 is supplied separately to the CVD reactor via a separate gas feed.
16. Process according to Claim 15, in which NH3 is supplied separately to the CVD reactor for producing the gas phase via a separate gas feed.

17. Method according to at least one of the preceding claims 15 or 16, in which a gas phase with 0.30% by volume to 2% by volume of NH3 is used.
18. Method according to at least one of the preceding claims 15 to 17, in which, prior to the deposition of the h-AlN-based hard material layer, at least one bonding, intermediate and/or covering layer of nitrides, carbides, carbonitrides, oxycarbides, Oxycarbonitrides of the elements of FIG. 4.-6. subgroup of the PSE or of oxides of the AI or Zr.

19. Method according to claim 18, in which a bonding, intermediate and/or covering layer is deposited with TiN, TiCN, TiAIN and/or combinations thereof.