Note: Descriptions are shown in the official language in which they were submitted.
CA 02523882 2012-08-03
. 30884-2
Work Piece with a Layer of Hard Material that Contains AlCr and a Method
for Producing This
The technical domain to which the present invention relates includes work
pieces that are
covered with a layer system that contains at least one (AlyCri-y) X layer as
defined herein.
The present invention also relates to a PVD process for depositing an
(AlyCri_y) X layer on a
work piece.
In particular, the present invention includes:
work pieces that are coated with hard material and have one or a sequence of a
number of different aluminum chromium nitride or aluminum carbon nitride
layers;
- tools, in particular cutting and forming tools (drills, milling tools,
turnover
cutting plates, thread cutters, thread formers, hob milling cutters, stamps,
matrices, drawing
tools, etc.), and the use of these tools with AlCrN or AlCrCN layers;
components, in particular components from the machine-building domain, such
as gear wheels, pumps, barrel tappets, piston rings, injector needles,
complete bearing sets or
individual parts thereof, and the use of these component parts with AlCrN or
AlCrCN layers;
a method for producing AlCrN or AlCrCN layers with a defined layer
structure.
One aspect of the invention relates to a PVD method for depositing at least
one (AlyCri_y)
N layer on a work piece, with 0.415 < y 0.695, wherein the work piece is
introduced into a
vacuum coating machinery with at least two compositionally different AliCri_z
targets with
0.25 < z < 0.75 and held at a pressure of 0.5 - 8 Pa during the addition of a
reactive gas that
comprises nitrogen, carbon, boron, or oxygen and the application of a
substrate voltage
between -3 to -150 V, applied as an arc or sputter source, such that the layer
composition
within at least one (AlyCri_y) N layer changes continuously or incrementally
across the
thickness of the layer.
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Another aspect of the invention relates to use of work piece with a layer
system that contains
at least one layer of composition (AlyCri-y) N, with a cubic structure, where
0.415 y 0.695, the composition of the layer changing over the thickness of the
layer
continuously or incrementally, the work piece being a milling tool, a
broaching cutter, a
reamer, a turnover cutting plate for turning and milling, a molding tool, an
injection-molding
tool, a forming tool or a hot-forming tool, for machining a material.
Different AlCrN layers are known from the prior art. JP 09-041127 describes a
wear-resistant
layer of hard material of the following composition (Ali_yXy) Z, wherein X =
Cr, V or Mg, Z
= N, C, B, CN, BN or CBN and 0 <Y 0.3. This layer has been used advantageously
to
increase the useful life of turnover cutting plates.
In their paper "Multicomponent hard thin films..., "Thin films (Proc. 4th Int.
Sympos. Trends
and New Applications of Thin Films 1993) DGM Info.gesellschaft Oberursel.
1993.) p. 73, D.
Schulz and R. Wilberg describe a CrA1N layer that, during a filling test,
doubled the service
life of a drill that was coated with TiA1N. The layer was precipitated by a
hollow cathode
process that, however, caused a pronounced variation
la
CA 02523882 2011-02-09
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of the chromium/aluminum distribution in the (CrADN layer because of an
intermittent
vapourization process..
In their paper titled "Oxidation Resistance of Cr i_õAl.N and Tii,AlõN Films,"
Surf. &
Coat Tech., Vol. 165, 2, (2003), pp. 163-167, M. Kuwate et al. describe a
Cr1_,,Al2N layer that, with a high aluminum content and wurzite structure,
displayed
improved resistance to oxidation as compared to conventional TiAlN layers.
In their paper titled "Investigations of Mechanical and Tribol Properties of
CrAlN + C
Thin Coatings Deposited on Cutting Tools," E. Lugschneider, K. Bobzin, and K.
Lackner
compare arced CrAlN layers and CrAlN layers that additionally have an even
harder
covering layer that contains carbon. All the layers display a coefficient of
friction that
rise rapidly to higher values.
It is the objective of the present invention to describe work pieces coated
with (AlyCri.y)
X, for example, machining tools, cutting and forming tools, or components for
machine
building and die making, as well as a method for depositing such layers on a
work piece,
and at the same time avoid the disadvantages found in the prior art.
This includes work pieces, for example, that are of an adjustable, even or
variable layer
composition, at least with reference to the Al/Cr ratio, and which display
greater wear
resistance, at least in specific applications, than work pieces that have
previously known
layers.
In order to investigate the wear resistance of (AlyCri_y) N or -CN layers on
different
tools, Cr layers with various aluminum contents were deposited on different
work pieces
in Type RCS industrial machinery (Balzer company), as described in EP 1186681
in
Figure 3-6, Description page 12, lines 26 to page 14, line 9.
To this end, the cleaned work pieces
were secured, depending on their diameters, on two- or, in the case of
diameters smaller
than 50 nam, on threefold rotating substratum carriers, and two titanium
targets and four
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targets produced by powdered metallurgy which were of different AlCr alloys
were built
into six cathodic arc sources attached to the walls of the coating machinery.
Next, the
work pieces were initially brought to a temperature of approximately 500 C by
irradiation
heaters similarly installed in the machinery, and the surface was subjected to
etching
cleaning by applying a bias voltage of -100 to-200 V in an Ar atmosphere at a
pressure of
0.2 Pa.
Subsequently, by operating the two Ti sources with a power of 3.5 kW (140 A)
in a pure
nitrogen atmosphere at a pressure of 3 Pa and a substrate voltage of -50 V for
a period of
five minutes, a TiN adhesive layer, approximately 0.21.tm thick, and an AlCrN
layer was
next deposited by operating the four AlCr sources with a power of 3 kW for a
period of
120 minutes. In order to achieve an optimum layer transition, the sources were
operated
jointly for a period of two minutes. Then a nitride layer on an AlCr base was
deposited
in a pure nitrogen atmosphere, also at a pressure of 3 Pa and a substrate
voltage of-SO V.
In principle, the process pressure in each of these steps can be set in a
range of 0.5 to
approximately 8 Pa, preferably between 2.5 and 5 Pa, and either a pure
nitrogen
atmosphere or a mixture of nitrogen and a noble gas such as argon can be used
for a
nitride layers, or a mixture of nitrogen and a gas that contains carbon which
can, if
necessary, have a noble gas added to it, can be used for carbon nitride
layers.
Accordingly, in order to deposit layers that contain oxygen or boron, oxygen
or a gas that
contains boron can be added, as known.
Layer properties such as the crystal structure of the layer, and layer
thickness, layer
hardness, wear resistance, and the adhesion of AlCrN layers as a function of
the chemical
composition and crystal structure, as well as the composition of the targets
that were
used, are set out in Table 1. Process parameters such as target power,
substrate bias
voltage, and process pressure and temperature, are set out in Table 2.
Table 3 shows a measurement series in which the AlCr layers were deposited
using
targets with an Al/Cr ratio of 3, during the application of various substrate
voltages.
When this is done, the wear resistance as determined with a precision wear
tester
3
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manufactured by Fraunhoferinstituts-IST Brunswick, when a calotte-grinding
method
that had been modified from DIN EN 1071-2 was used in order to determine the
rate of
wear. The details of this method can be found in Michler, Surf. & Coat. Tech.,
Vol. 163-
164 (2003), P. 547, Col. 1, and Figure 1.
The present invention will be described in greater detail below on the basis
of the
drawings appended hereto. These drawings show the following:
Figure 1: XRD spectrum of an AlCrN with B1 and B4 structure;
Figure 2: XRD spectrum of an AlCrN as a function of the chemical composition
Al/Cr:
A = 75/25, C = 50/50, D = 25/75.
As can be seen from Table 1 and Figure 1, and as is known from Kawate, "Micro-
hardness and lattice parameter of Cri-xA1x N," J. Vac. Sci. Technol. A 20 (2),
Mar/Apr
2002, pp. 569-571, an hexagonal (B1) layer structure could be established for
Al
proportions of > 70 AT% of metal content in the layer, and a cubic (B1)
lattice structure
could be established for smaller Al proportions. For hexagonal layers, HV
values of
approximately 2100 HV0.05 could be measured, although for cubic layer
structures higher
HV values of approximately 2800-3100 HV0.05 could be measured (see Table 1).
At
higher Cr contents (Sample D), a hardness of approximately 2300 HV0.03 was
established.
At this composition, as distinct from the AIN lattice with a high aluminum
content, as is
shown in Figure 2A, there is a CrN lattice as in Figure 2D.
Next, the service life of 6 mm HSS drills coated with AlCrN was determined on
DIN
1.2080 steel material with a hardness of 230 HS at a feed of 0.12 mm and a
cutting speed
of 35 m/min as in Example 1 below. When this was done, it was revealed that,
in
contrast to the range of (AlyCri_y) N <Y Ø7 that was described as being
particularly
favorable in JP 09-041127, a chromium content of greater than 0.3 was
advantageous.
At chromium contents of greater than or equal to 0.8, the productivity fell
once again for
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this range of application because of the existing CrN lattice. In this case,
the increase in
service life of cubic as compared to hexagonal AlCrN layers amounted to 235%.
For layers in a transition range with an aluminum content between 60% and 75
at%, it is
possible to adjust not only the preferred orientation, but also the underlying
structure of
the crystal lattice, by way of the process parameters. Thus, for example, in
Test B (Table
2) at a low pressure of 1 Pa and a substrate voltage of -50 V, an hexagonal
structure is
generated, whereas in a pressure range from 3 Pa and the substrate voltage of -
50 V, a
cubic structure is generated. The hexagonal structure is thus deposited at a
relatively
lower bias voltage and low pressure, whereas the preferred cubic structure is
deposited at
higher pressure or at the amount according to a higher bias voltage. It is no
longer
possible to generate a cubic layer structure at higher aluminum contents.
Work pieces according to the present invention are thus distinguished by a
cubic
(AlyCri -) X coating of the following composition: X = N or CN, but preferably
N, and
0.2 < Y < 0.7, preferably 0.40 < y < 0.68. The layer structure is
microcrystalline with a
median grain size of approximately 20-120 nm.
The methods according to the present invention are distinguished by a sequence
of
operations in which a cubic (AlyCri_y) X layer of a composition as defined
above is
deposited. Target compositions of 75 to 15% aluminum content can be used
advantageously for the cathodic arc method described above. At high aluminum
contents, process parameters are to be set as described above in order to
generate a cubic
crystal structure.
When this is done, it is advantageous to use targets produced by powder
metallurgy, in
particular by cold pressing; these targets display greater strength than Al/Cr
targets
produced by fusion or sintering, which mostly contain brittle phases,
particularly at high
aluminum contents.
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Such targets are cold pressed by mixing the powdered starting materials and
then
compacted by repeated forming, for example in a forging press, at temperatures
below
660 C during flow and low-temperature welding, and brought to an end state
with a
theoretical density of approximately 96-100%.
In addition, it could also be established that with an AlCrN coating that was
deposited,
for example, using targets of a composition Al/Cr = 3, wear resistance could
be
influenced by the substrate bias voltage. As the substrate bias voltage rises,
resistance to
abrasive wear declines (see Table 3). Even at a very small-substrate voltage,
which is not
shown explicitly in the table, of only a few volts (3-10 V and any intervening
values), it
is possible to achieve a clear improvement as compared to floating substrates
(no external
voltage supply). At approximately -20 V, wear resistance for AlCr = 3 reaches
a
maximum and falls once again at higher voltages. An optimal range of substrate
voltage
between 3 to 150 V, in particular between 5 and 40 V, can be derived from the
test to
determine wear behavior; a very low rate of wear between 0.4 and 1.0, in
particular
between 0.4 and 0.8 m3m-IN-110-15 can be derived, was measured in these. The
same
applies for layers according to the present invention, which is to say, cubic
layers with
different Al/Cr composition at which no wear rates above 1.5 m3m-2N-110-15
were
measured. It should be noted however, that the wear resistance of floating
layers
deposited at a higher substrate voltage is significantly greater than the wear
resistance of
known TiAlN layers, the wear coefficient of which is significantly greater.
For example,
a wear rate of 3.47 m3m-IN-110-15 was measured for a TiAlN layer deposited
analogously
to the AlCrN layers (Experiment 2, Al 47 at%, Ti 53 at%).
Using TiAl targets produced by the method described above, in particular by
powder
metallurgy, it is possible to deposit layers having a low level of roughness.
The
measured Ra values lie in the range between 0.1 and 0.2 pm and are thus in the
same
range as comparably produced CrN layers. Further smoothing of the layers will
result
from the use of a magnetic field generator that includes two magnetic systems
of
opposing polarity and which is so configured that the B1 component of the
resulting
magnetic field that is perpendicular to the surface displays essentially
constantly small
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values across the major part of the service, or is zero. At the same time, the
value of the
perpendicular B1 component is less than 30 and preferably less than 20, and in
particular
is less than 10 Gauss. The Ra value of the (AlyCri-y) X layers that are
deposited thereby
lie in the range from 0.05 to 0.15 gm. The magnetic field was generated by two
coils of
opposing polarity arranged coaxially behind the target.
In addition, during the precipitation of (AlyCri-y) X layers, other preferably
highly
conductive nitride or metallic adhesive layers can be used, or the use of such
an adhesive
layer can be dispensed with for certain applications. For example, in order to
achieve
particularly high productivity, an A1Cr-/A1CrN- adhesive layer can be applied
in place of
a TiN adhesive layer, which makes it possible to provide all the arc sources
of a coating
machinery with AlCr targets and increase the coating rates.
In the same way, it is also possible to deposit gradient layers with, for
example,
aluminum contents that increase towards the surface, if two target types with
a different
Al/Cr ratio are used or if, proceeding from a Cr and/or CrN adhesive layer, a
change in
the layer composition is achieved by, for example, continuous or incremental
regulation
of the corresponding target powers of a coating chamber that is equipped with
Cr as well
as AlCr targets. What is important for an industrial application of such a
coating system
is the possibility of setting up the process parameters so that they can be
replicated
essentially across the whole coating sequence, and thus across the whole
thickness of the
layer. Minimal variations in the composition, like those brought about by
substrate
movement, for example, on a single or multiple rotating substrate carrier, can
be used
additionally for nanostructuring that is formed partially or across the whole
thickness of
the layer, i.e., lamination in the nanometer or micrometer range. If unalloyed
chromium
and aluminum targets are used, a more coarsely structured hard layer will be
precipitated
than is the case when alloyed AlCr targets are used.
Less suitable for this purpose, however, are processes known from the prior
art in which,
for example, the vaporization process of a least one component is difficult to
manage or
is intermittent, since no reproducible layer quality can be achieved thereby.
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It is, of course, possible to produce layers of this kind using other vacuum
coating
machinery or, for example, by sputtering processes, although ionization of the
process
gases, which is in principle lower, must under certain circumstances be
balanced out by
known measures such as special adhesive layers, additional ionization, etc.,
in order to
achieve comparable layer adhesion.
In principle, using the CrAlõN layers with a cubic structure it is possible to
coat very
different work pieces. Examples of these are cutting tools such as milling
tools, hob
cutters, round-head, flat, and profile milling tools, as well as drills,
threading taps,
reamers, and turnover cutting plates for turning and milling work, or forming
tools such
as, for example, stamps, matrices, drawing rings, ejector cores or thread
formers.
Injection molding tools, for example, for metal injection molding alloys,
plastics, or
thermoplastic, in particular injection molding tools such as those used for
producing
molded plastic parts or data carriers such as CDs, DVDs etc., can also be used
and can to
advantage be protected by layers of this kind. A further range of applications
includes
components that demand wear resistance which under certain circumstances is
coupled
with great resistance to oxidation. For example, sealing rings, pistons,
stamps, gear
wheels, and valve gear such as barrel tappets and rocker arms, or needles for
injectors,
compressor shafts, pump spindles, or many components to which one or plurality
of
meshing elements are attached.
Additionally, because of the behavior of (AlyCrl-y) X layers, which is, in
principle,
similar, an improvement in wear behavior can also be anticipated if in the
following layer
systems target composition and coating parameters are so selected that a cubic
layer
structure is achieved.
(AlyCri_y) X wherein X = N, C, B, CN, BN, CBN, NO, CO, BO, CNO, BNO, CBNO,
preferably, however, N or CN , and 0.2 < Y <0.7, preferably 0.40 < Y < 0.68
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(A166Cr34) NO layers with different N/O ratios were deposited thus and then
their layer
properties were tested. The coating parameters were selected so as to be
similar to those
selected above. The total pressure was between 1 and 5 Pa at an oxygen flow
between 20
and 60 sccm (remainder nitrogen), the substrate voltage was between -40 to -
150 V, the
temperature was 450 C, and the source power at a current of 140 A was set at
3.5 kW.
This produced layers with 0/N ratios of approximately 0.2, 0.6, and 2.2. The
layers with
the low oxygen content proved to be superior in different milling tests. The
results were
clearly better than the service lives achieved with conventional TiN or TiCN.
Because of the improved slip properties of the (AlyCri_y) X layers discussed
above, there
is the possibility -- which is interesting from both economic and ecological
standpoints ¨
of dispensing with lubricants when operating tools, in particular cutting
tools and forming
tools, or else use only minimal quantities of such lubricants. From the
economic
standpoint, one must take into account the fact that the costs for cooling
lubricant, in
particular in the case of cutting tools, can be greater than the cost of the
tool itself.
An even more far-reaching possibility for improving the slip properties of a
layer system
according to the present invention, which contains an (AlyCri-y) X layer, will
result if a
slip layer is applied as the outermost layer. It is advantageous if the slip
layer is of a
lower hardness than the (AlyCri -) X layer and possesses break-in
characteristics.
The slip-layer system can be built up from at least one metal or from a
carbide of a least
one metal and dispersed carbon, MeC/C, the metal being a metal from the group
IVb, Vb
and/or VIb and/or silicon. For example, a WC/C cover layer of a hardness that
can be
adjusted between 1000 and 1500 HV, and which possesses excellent break-in
characteristics, is well-suited for this. Cr/C layers display a similar
behavior, although at
a somewhat higher coefficient of friction.
In the case of deep-hole drill bits coated in this way, after the production
of one to three
bore holes, it was possible to see excellent break-in smoothing which, up to
now, could
only be achieved by means of costly mechanical machining. Such properties are
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interesting, in particular, for component applications that are subjected to
slip, friction, or
rolling stresses, with little lubrication or when running dry, or if an
uncoated opposing
body is to be protected at the same time.
Additional possibilities for forming a finishing slip layer are metal-free,
diamond-like,
carbon layers, or layers containing MoSõ, WS, or MoSx or MoWx layers that
contain
titanium.
As discussed, the slip layer can be applied directly on the (AlyCri_y) X layer
or after
application of an additional adhesive layer, which can be formed as metal,
nitride,
carbide, or carbon nitride, or as a gradient layer with, for example, a
continuous transition
between (AlyCrt-y) X and slip layer, in order to bring about the best possible
adhesion of
the layer bond.
For example, after the application of a sputtered or arced Cr or Ti adhesive
layer, WC/C
or CrC/C layers can be produced, advantageously by sputtering of WC targets
during the
addition of a gas that contains carbon, when the proportion of gas that
contains carbon is
increased over time in order to arrive at a greater proportion of free carbon
in the layer.
Further advantageous applications for different (AlyCrt_y) X hard coated tools
are
described below, their use for different cutting operations serving as
examples.
Example 1: Milling structural steel
Tool: Shank-type cutter
Diameter D = 8 mm, tooth count 3
Material: Ck 45 structural steel, DIN 1.1191
Milling parameters:
Cutting speed: vc = 200/400 m/min
Feed speed vt: 2388/4776 mm/min
Width of radial contact a,: 0.5 mm
Width of axial contact: ap: 10 mm
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Cooling: Emulsion 5%
Process: Constant speed milling
Wear criterion: Free-surface wear VB = 0.12 mm
Experiment Metallanteil [Att)(:71 Etandzeit t bti VS W,12 mm
rir. . Schicht-\4*.j in Minuhan
Ti Al Cr v5 m 200 m/min vc. = 400 m/min
1 (TiCN) 100 71 9
_2 (riAlai) 53 47 42 = 15
3 (A3.CrN)81 69,5 30.5 167 40
AlCeN) B4 72 28 41 7
=
(L1CrN)111 41,5 58,5 150 12
6 (AlCr2i)S1 19 81 17 4
Key: 1 ¨ Experiment Number; 2 ¨ Proportion of metal (At%) Layer; 3 - Standard
times t
at VB = 0.12 mm in minutes
Example 1 shows a comparison of the standard times of coated HM milling tools
that
were tested using different cut parameters.
It is clear that the AlCrN layers referred to have longer service lives as
compared to the
layer systems used in industry up to the present time, such as TiCN and TiA1N.
In
addition, the results show that, as in Example 1, the service life behavior
improves as the
aluminum content increases, to the extent that the cubic B1 structure is
maintained, as is
the case in Example 1 (compare Experiments No. 3, 5, 6). This can be
attributed above
all to the improved resistance to oxidation and hardness that can be seen with
the
increasing aluminum content (see Table 1). The very good resistance to
oxidation of the
AlCrN coating becomes particularly noticeable in the range of dry and high-
speed
machining (e.g., vc = 400 rpm). Furthermore, this test, too, shows that when
the crystal
lattice is collapsed from B1 to B4, the structure of the wear behavior is
degraded
(compare Experiments 3 and 4).
Example 2: Milling austenitic steel
Tool: Shank-type cutter, hard steel
Diameter D = 8 mm, tooth count 3
Material: X 6 CrNiMoTi 17 12 2 austenitic steel, DIN 1.4571
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Milling parameters:
Cutting speed vc = 240 m/min
Tooth feed speed f?? = 0.08 mm
Width of radial contact ap = 0.5 mm
Width of axial contact: 10 mm
Cooling: Emulsion 5%
Process: unidirectional milling
Wear criterion: free-surface wear VB = 0.1mm
=tveriment z4lt.411antoi1 (2,,ti,1 0 Standweg boi VL 0,1
null
Nr, .Sobicht in Meter
0
Al ____________________________
(TiCW) 100 33 _________
(UTiS) 35 f) 45
9 µAlCrM) 91 - 69,5 313,S 54
Key: 1 ¨ Experiment Number; 2¨ Proportion of metal (At%) Layer; 3 - Standard
path 1,
at VB = 0.1 mm in meters
Example 2 shows a comparison of the service lives of coated HM milling tools.
Here, in
the same way as with the AlCrN layer, it is possible to achieve an improvement
of wear
as compared to the layers of hard material used in industry. In the case of
AlCrN, the
improvement in service life could be achieved, on the one hand, by a lesser
inclination --
as compared to the Ti in TiAlN layers -- of the second alloying element Cr to
spread,
which up to now remains unproved and, on the other hand, by the clearly good
resistance
to wear displayed by AlCrN layers (A, B, D) according to the present
invention, as set
out in Table 1, at a simultaneously high degree of hardness.
Example 3: Milling hardened steel
Tool: Ball-head cutter
Diameter D = 10 mm, tooth count z = 2
Material: K 340 (62 HRC), corresponding to C 1.1%, Si 0.9%, Mn 0.4%, Cr 8.3%,
Mo
2.1%, Mo2.1%, V 0.5%
Milling parameters:
Cutting speed ve = 0 - 120 m/min
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Tooth feed speed fx = 0.1 mm
Width of radial contact as = 0.2 mm
Width of axial contact ap: 0.2 mm
Cooling: Dry
Process: Unidirectional and bidirectional milling, planishing
Wear criterion: Free-surface wear VB = 0.3 mm
Experimeat Metailenteil LAtqs] a) St&ndweg it bei VB = 0,3
1kTr.
0 SChicht mx in MoLeK
Ti Al Cr
(TiA114) 53 47 4 - = 7U
11_(A1crN) B1 - 69.5J30,5 90
Key: 1 ¨ Experiment Number; 2 ¨ Proportion of metal (At%) Layer; 3 - Standard
path at
VB = 0.3 mm in meters
Example 4: Rough milling tool steel
Tool: Shank-type cutter, hard steel
Diameter D = 10 mm, tooth count z = 4
Material: X 38 tool steel X 38 CrMoV 5 1, DIN 1.2343 (50 HRC)
Milling parameters:
Cutting speed ye = 60 m/min
Tooth feed speed fx = 0.02 mm
Width of radial contact a?? = 2 mm
Width of axial contact ap: 10 mm
Cooling: Dry
Process: Unidirectional milling, roughing
Wear criterion: Free-surface wear VB = 0.1 mm
.7 ----
xp er imen t Metellanteil (AVG) StandWeg 1: bei VD -
Nr. Schicht mil in meter
. cr __
11111,1111111111 6:3 __________________ 90
11111MMINIMII 69,5 30,5 130
Key: 1 ¨ Experiment Number; 2 ¨ Proportion of metal (At%) Layer; 3 - Standard
path at
VB =0.1 mm in meters
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Example 3 and Example 4 display an improved standard path of the AlCrN layer
as
opposed to the TiAlN layers used in industry. AlCrN is particularly well-
suited for dry
machining that imposes great demands with respect to resistance to oxidation
and
resistance to wear.
Example 5: Drilling in tool steel
Tool: HSS drill bit (S 6-5-2) Diameter D = 6 mm,
Material: X 210 tool steel, Cr 12 DIN 1.2080 (230 HB)
Cutting speed Ve =35 m/min
Drilling parameters:
Feed f= 0.12 mm
Bore hole depth z = 15 mm, blind hole
Cooling: Emulsion 5%
Wear criterion: torque shutoff (corresponding to erosion wear of > 0.3 mm
Experiment Nr. Metall antett t% I 0 etandweg
Schicht (Lochzahl / pia
Al , Cr Schichtdicke]
14 (AlCal B1 19 In 22.
_
15 IA/CrNI 81 41,S
58 5
52
16 (AlCrCN) B1 42.5 58,5 65
17 (A1CrN) 81 69.5 30,5 IOU
18 (AlCrN) 84 72 28 46
Key: 1 ¨ Experiment Number; 2 ¨ Proportion of metal (At%) Layer; 3 - Standard
path
(hole count/pm layer thickness)
Example 6 shows a comparison of the hole count, standardized on the basis of
layer
thickness and achieved with HSS drill bits with AlyCri -y N/ AlyCri -y CN
layers with
different Al contents.
The layers were produced with the parameters set out in Table 2. As the
aluminum
content increase, there was an increase in the service life up to not quite
70% aluminum
in the metal content. In the case of a further increase, and thus the
precipitation of a layer
with an hexagonal crystal structure, performance falls off. In the range
between 41.5 and
14
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69.5% aluminum (Experiment 15, 17) it is possible to establish a clear
increase in
performance in this application as compared to the prior art (Experiment 18).
Example 6: Deep hole drilling 5 x D in Ck 45
Tool: Drill bit hard metal, Diameter D = 6.8 mm,
Material: Structural steel, 1.1191 (Ck 45)
Drilling parameters:
Cutting speed vs = 120 m/min
Feed f= 0.2 mm
Bore hole depth z = 34 mm, blind hole
Cooling: Emulsion 5%
Wear criterion: Erosion wear VB = 0.3 mm
Experiment Matallanteil (Atit)(0 Stendzeit t bai VB 0,1
Nr. Sohicht , 4mm in
C2 Cr Antahl Bohrldcher 0
18 (11.10.11) 70 30 090
19 tTiA114) 53 47 1135
20 3311CeN)B1 69,S . 30,5 2128 _______
Key: 1 ¨ Experiment Number; 2 ¨ Proportion of metal (At%) Layer; 3 - Standard
time t
at VB = 0.3 mm in number of bore holes
Example 6 shows an improved service life of the AlCrN layer as compared to the
TiAlN
layers, as used industrially, in a drilling application. Here, the improved
resistance to
abrasive wear of the AlCrN coating according to the present invention becomes
obvious.
In addition, drill bits coated as in Experiment No. 20 were provided with a
WC/carbon
slip layer after application of a Cr adhesive layer, whereupon a clearly
improved service
life could be achieved under otherwise identical test conditions. Torque
measurements
conducted at the same time revealed a clearly smaller torque moment than is
observed
without a slip layer. In addition, it is possible to see a better surface
quality and, until
shortly before the end of the service life, no coloration brought about by
excessive
temperature stress.
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Example 7: Tapping 2xD in austenitic steel
Tool: HSS screw tap , thread dimension M8
Material: Austenitic steel, 1.4571 (X6CrNiMoTi 17/12/2)
Drilling parameters:
Cutting speed IT, --= 3 m/min
Thread depth: 2XD
Thread type: blind hole
Number of threads: 64
Cooling: Emulsion 5%
Wear criterion: Torque progression over thread count, visual assessment of
wear after 64
threads.
Exporiment N. matalleultoil =
SchiCht
Ti Al Cr cut,,x,(2)- Optischar
Schnittm=ent Varachloi
T111) (1)
õ21 (TiCN) 100 4,72 ___________
22 (A1CrW)131 69,5 30,5 4,05 = +4.
-
,23 (AlCrN)1 - 41,5 59.5 4.23
+++
24 (AlerN)151. 19 81 4,2,
Key: 1 ¨ Experiment Number; 2¨ Proportion of metal (At%) Layer; 3 ¨0 maximum
cut
moment (Nm); 4 ¨ Visual wear (1)
Explanation of (1)
+ Wear behaviour satisfactory during tapping
++ Wear behaviour good during tapping
+++ Wear behaviour very good during tapping
A reduction of the average maximal cutting moment is achieved with all the
layers
compared to the prior art. In addition, because of the very good wear
resistance of the
layers with the higher aluminum content, there is improved wear behavior
compared to
TiCN. Certainly, in this example, presumably because of the adhesive tendency
of the
aluminum, which leads to material spreading and subsequently to layer
breakdown, the
16
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layer in Experiment 23 displayed a better wear image than Experiment 22.
Additionally,
screw taps coated as in Experiment Nos. 22 and 23, were provided with a
WC/carbon slip
layer or, after application of a Ti adhesive layer, were provided with a MoS2
layer
containing Ti, whereby an improvement in service life and better surface
quality of the
machined material could be achieved under otherwise equal test conditions.
Example 8: Hobbing in CrMo steel
Tool: Hob milling machine
Material: DIN 86-7-7-10 (ASP60)
Diameter: D = 80 mm, length L = 240 mm, Modulus m = 1.5
25 chip grooves
Angle of engagement a = 20
Reference profile 2, tooth count 50, thread width 25 mm
Material: Cr-Mo steel DIN 34CrMo4
Cutting parameters:
Cutting speed V, = 260 m/min
Feed: 2 mm/U
Piece count: 300
Cooling: dry cut, compressed air to remove chips.
______________________________________________________ -
Experiment :eteitaterfe (Aft) 122
... TorTchlfaieemerKentsyite
Nr.
0 - Ti Al Cr PreifIgenv.
Kokkver-0
schleies
25 (TiCN) 100 0,32 0,062
26 (TiA21) 53 47 - 0,25 0,042
.27 (A1CrN)134 72 20 0,2 0,053
28 (A1CrN)111 - 19 81 = 0,J6f
__________________________________________________ 0 051
29 (A1Cr14)111 - 4a-,5 68.5 0,13 0,022
30 (A1CrN)131 - 69,5 30,5 0,14 0,010
Key: 1 ¨ Experiment Number; 2¨ Proportion of metal (At%) Layer; 3 ¨ Width of
wear
marks in (mm); 4 ¨ Free surface wear; 5 - Erosion wear
In Tests 25 to 30, different hobbing cutters made from high-speed steel (HSS)
produced
by powder metallurgy and with different layer systems were tested during dry
cutting. A
significant improvement as compared to known TiCN or TiAlN coated cutters
could be
17
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achieved with tools coated as in the present invention (Experiment 29 and
Experiment
30). In the same way, it must be acknowledged that AlCrN layers with a low
(No. 28) to
high aluminum content offer a lesser degree of protection against wear if an
hexagonal
crystal structure is present (No. 27).
The following examples, Nos. 31 to 33, also shows the clear superiority of an
AlCrN
layer according to the present invention, with a cubic crystal lattice in the
essentially
stochiometric nitrogen proportion and an aluminum content of 66%. Milling
cutters
made from PM HSS or hard metal were tested both for dry and for emulsion-
lubricated
cutting.
Experiment No. 31: Hobbing
Tool: PM HSS
Diameter: D = 80 mm, length L = 240 mm
Cutting speed: 180 m/min
(A10.42Ti0.56)N, balinite NANO: 1809 pieces
(A10.63Tio.39)N, balinite X.CEED 2985 pieces
(A10.65Cro.36)N 5370 pieces
Experiment No. 32 Hobbing
Tool: Hard metal (HM)
Diameter: D = 60 mm, length L = 245 mm
Modulus: 1.5
Angle of engagement ??? = 20
Material: 42 CrMo4
Cutting speed: 350 m/min, dry
(A10.41Ti0.39)N, balinite X.TREME 1722 pieces
(A10.53Tio.37)N, balinite X.CEED 2791 pieces
(A10.65Cr0.34)N > 3400 pieces
Experiment No. 33: Hobbing
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Tool: PM HSS
Diameter: D = 80 mm, length L = 240 mm
Modulus: 2.5
Material: 16MnCr5
Cutting speed: 140 m/min, emulsion
TiCN, BALINITE B: 1406 pieces
(A10.42Tio.56)N, balinite NANO: 1331 pieces
(A10.66Cro.34)N 1969 pieces
Additional tests, not described herein, showed that even at still higher
speeds, up to vs =
450 m/min, durability remained good. Standard times of hard-metal hob cutters
could
also be improved noticeably during wet and, in particular dry, machining.
Example 9: Rough milling tool steel
Tool: Shank-type cutter
Diameter D = 10 mm, tooth count z = 4
Material: X 40 tool steel CrMoV 5 1, DIN 1.2344 (36 HRC)
Milling parameters:
Cutting speed vc =60 m/min
Tooth feed speed fa = 0.05 mm
Width of radial contact ax = 3 mm
Width of axial contact ap: 5 mm
Cooling: Emulsion 5%
Process: Unidirectional milling, roughing
Wear criterion: Free-surface wear VB = 0.1 mm
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¨ ______________________________
Exparimg-nt metallanteil (At%) Standwig lf boi VB
0 ,Schicht in Meter
Ti Al Cr
34 (211T1)N 35 65 6 - 8
35 (AlTi)N 58 42 3 - 4
36 (AlTi)CN 50 50 3 -
37 TiCH 100 0 - 11
,30 (Aler)N HS 64 36 12 - 21
39 (AlerIN pule 66 34 21 -20
,40 (Aler1N 66 34 , 12 - 10
HS = Adhesive layer of TiN
puls = pulsed
Key: 1 ¨ Experiment Number; 2 ¨ Proportion of metal (At%) Layer; 3 - Standard
path
1??? at VB = 0.1 mm in meters
Example 10: External machining of hardened carburizing steel
Tool: Turning tool with soldered-in CBN insert
Material: Carburizing steel 16 MnCr 5, DIN 1.7131 (49 ¨ 62 HRC)
Turning parameters: hard-soft machining with interrupted cut and partially
thinner wall
thickness
Cooling: dry
Wear criterion: piece count up to achievement of free-surface wear of VB = 0.1
mm
Experiment MAhallanteil (At%) (D Stidinn; ji VB--.. 0,1 Mm
Nr. 0 Sebicht
T4 Al Cr
,41 (AlTi)N 35 65 90
42 (AlCr)H 66 34 144
Key: 1 ¨ Experiment Number; 2 ¨ Proportion of metal (At%) Layer; 3 - Standard
quantity at VB = 0.1 mm in meters
Similar results were also obtained with cermets produced by powder metallurgy
consisting of a TiN, TiC, or a Ti(CN) hard phase, to which molybdenum and or
tantulum
was added. Ni or Ni/Co was used as a binding phase.
CA 02523882 2005-10-26
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2004/0659030 PCT/CH2004/000180
Example 11: Thread forming in galvanized steel
Experiment No.: 43:
Tool: HSS MS thread former
Material: DC01 corresponding to DIN 1.0330 St 12 ZE
Tapping drill hole diameter: 8.34 mm
Cutting parameter: 55 m/s
Cutting speed: 2000 rpm
Return speed: 3600 rpm
Lubrication: S26 CA
TiN: 3200 threads
TiCN 3200 threads
TiAlN 3500 threads
(A10.66Cr0.34)N 8800 threads
Tests with coated CBN (cubic boron nitride) or cermet tools: turnover cutting
plates of
different CBN sintered materials with a CBN content between 30-99vo1-%,
remainder
binding agent, were coated, on the one hand, with known TiAlN layers as in
Experiment
8, and, on the other hand, with AlCrN layers as in Experiment 3, Experiments
3, and
Experiment 6. Because of the non-conductive nature of the CBN sintered
material, a
pulsed substrate bias in the middle frequency range, preferably in a frequency
range from
20 to 250 kHz, was applied for the etching and coating process.
For materials with a CBN content of up to 90%, a bonding agent powder was used
that
consisted of at least one of the elements from the following group: nitride,
carbide,
boride, and oxide of the Ti, V, or Cr group, i.e., IVa, Va, and VIa elements,
as well as
aluminum or aluminum compounds.
For materials with a CBN content of up to 95% a bonding agent powder was used
that
consisted of titanium nitride and the least one of the elements from the
following group:
cobolt, nickel, wolfram carbide, aluminum, or an aluminum compound.
21
CA 02523882 2011-02-09
30884-2
For materials with a CBN content of greater than 90%, a bonding agent powder
was also
used, consisting of titanium nitride and and at least one of the elements from
the
following group: boride or boron nitride of the alkali or earth-alkali metals.
During turning and milling tests conducted subsequently it was, in most
instances,
possible to see wear behavior that was greatly improved as compared to TiAlN
layers. It
was the same in the course of a particularly exhaustive external machining
test in which a
shaft of complex geometry that was only partially hardened and was machined in
part
during interrupted cutting.
Example 12: Hot forging
Tool: 4 forging jaws 220x43x30 mm, drill W350, hardness 54 BRC, 4 tools
engaged
simultaneously
Work piece: round stock, diameter 22 mm, material 42 CrMo4
Method: Temperature of work piece before forming 1050 C Pressing force 57 t
per jaw
Cooling: MolicoteTm + graphite
Experiment Metananteil !)t)
Ur. Schicht Stand:mango
Ti Al Cr Nb/6i (StOckzuh).)
V/w
43 unheoch. - - 500
44 'XJ10_17 58 42 - 900
,45 AlCrN 64 36 1900
46 hlerVN , 63 , 31 6 1500
47 AICrSiN HS 65 26 õ = 1800
49 AlerNlaw ¨7=t¨ 62-'7-31 -7 135T-
,49 A1CrW4 65 26 9 1630
50 A1CrTg _62 31 7
1730
51 AlCrMoN 62 31 7 1460 .
HS = Adhesive layer of TiN
Key: 1 ¨ Experiment Number; 2 ¨ Proportion of metal (At%) Layer; 3 - Standard
quantity (piece count)
22
=
1
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Example 13: Hot bordering
Tool: HM flowdrill, diameter 10 mm
Method: The tool was pressed against the work piece at 2800 rpm, at 3000 N.
The work
piece was brought to red heat, i.e., approx. 1000 C and formed by kinetic
energy.
_ _______________________________________________
experiment Hetallanteil (Atli) 0
N. Schicht
1- 31 Otandmonge
0 Ti Al Cr Nb/Si
(StUckzahl)
\) 52 unbesch. - - .. - SOO
i
53 TiA1N 58 42 . -900,
----...¨.
54 AlerN - 64 36 - 1700 .
55 AlCrVN ., 63 31 6 1530
56 AlCrSiN HS 65 26 9 1650
---
57 11Cr74bN - 62 32 7 1450
58 AlCrWN - 65 26 9_ ____________ 1390 __
_ _
59 A1CrYN - 62 31 7 ,. 1600
______________________________________________________________ -
6D AlerNoN - 62 31 , 7 1340
HS = Adhesive layer of TiN
Key: 1 ¨ Experiment Number; 2 ¨ Proportion of metal (At%) Layer; 3 - Standard
quantity (piece count)
Example 14: Stamping
Tool: 1.2379 slot punch 20 x 10 mm
Work piece: TRIP 700, 1.2 mm thick
Method: Shearing, cutting gap 10%, 500 strokes/min
Cutting force: 20 kN
-
_ \J
_ _____________
Experiment. Metallantail (Attl ()
Elr.
0 V. = AA Cr 103/61. . :StAlckzehll
., V/W
,61 unbeach. 4 ... , - - _ 100000 1
62 TihIN 58 42 - - 200000 ....._ _
GS AlCrN - 64 36-
350000
¨
64 41CrVIT - 61 , 31 6 370000
_
65 AlCrSiN HS 55 26 9 200000 ¨
66 AlCrNIAN . 62 11 7 . 300000 ,
67 AlerWN - 65 26 9 140000
68 AlCrYN ,_ - 62 _ 31 7 _ 320000 1
69 AlCrHoN - 62 , 31 7 290000
23
,
CA 02523882 2005-10-26
' = WO 2004/0659030
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HS = Adhesive layer of TiN
1
tr. I I
r.
v".4 r.I ri ri 6
-¶
...4 1
rclIZZ tr.,'= I 2 I = ',j,t :) M .t k t:-.--,
4 ,,,'4 ,,-;' LT; didlgigL
it
, 1 1
I _____________________________________ i i
to i ' . i- ,4--r-----r¨i
4 , i, . 1
1
...; r:4 ID tu g 1 i I I
1 #4 = 74_ b : F ..r., .:4 -t ', ,e, 1 .r:.,
1 ,c;, I
,
m 0,1 r-4 co et i
el rl
i....,,...,
1 _________________________ ,
.
1 ''''.i' =r-t . 14 4 t='; =4
Z to ===='' .. ...,
.5? ! 2$ 2 2
i- .., , ..0 ... f ....., 1
I I i 1
l' ---l--1
),,, 4., = i co . i r-. I ,
i ' 1
i,,-,1....1, 1,n;
¨ _________________________
41 1
a: P I .-:; 1 ti _____ 1--- i' ---i¨i
i
oz.
1 I i
v, {
.4 ¨ CZ, ' G. i 10 . i.r. ;
1, ________________________________ 16 E. .f, 1.7,^ I id': ,
,..r1 :
J , ,
4,4 1 ,g ,4 in, mielr
1
' i I lig .6 El
LI ."1 41) t't rn r-i rn =C.1ei I ..-, I fl
1
4 H AC 1.4 01
4L'
I II I gd I 1 1 ! I
i _______________ t __ 1 ________________ 1 _____
V64 1=1 (C) , ,
(ti I = NV
eq "
V 0 4. tx4 cv, A I :741 1 tl, t'-=-;,<IM c-
dg....,
,-i
1 =
aril,..i.eq i 1
1 1 1
Key: Key: 1 - Test Number; 2 - Proportion of metal (At%) Layer; 3 -
Crystal
structure; 4 - Layer thickness (gm); 5 - Adhesion
24
