|Title of Invention
A COMPOSITE MATERIAL
|A composite material comprised of: a base substrate body; a first coating on the base body of a multiphase layer of titanium oxide and at least two oxides from the group of aluminum, zirconium, and hafnium oxide and a second single-phase layer on the first layer consisting of only one oxide of aluminum, zirconium, and hafnium; and a second coating on the first coating of a multiphase layer of titanium oxide and at least two oxides from the group of aluminum, zirconium, and hafnium oxide and a second single-phase layer on the respective first layer consisting of only one oxide of aluminum, zirconium, and hafnium.
FIELD OF THE INVENTION
The invention relates to a composite material of a base body with a multi-layer coating. Such
composite bodies are, for example, used as cutting inserts for machining purposes, namely,
turning, milling or boring. The base bodies, to which the coating can be applied by physical
or chemical vapor deposition processes. (PVD or CVD), can be composed of hard metal, a
cermet, steel or a ceramic.
BACKGROUND OF THE INVENTION
DE 27 36 982 A1 already describes a wear resistant coating for shaped parts, especially for
tools, comprised of a shaped body, preferably of hard metal, and one or more surface
coatings, at least one of which is a protective layer with a ceramic matrix into which a further
material is incorporated. The ceramic matrix and the material incorporated therein have
different coefficients of thermal expansion so that the protective layer is subject to the
formation of fine microcracks therein. Unstabilized and/or partially stabilized ZrO2 has been
proposed as the material incorporated into the interstices of a ceramic matrix of Al2O3. To
produce such a layer by the CVD process, AlCI3, CO2 and H2 are admitted as a gas phase into
a reaction vessel at 1100° C. to produce Al2O3 or ZrCl4 and water vapor (H2O) are admitted to
produce ZrO2. Because of the density difference between the tetragonal modification of ZrO2
formed at temperatures above the transformation temperature of about 1100° C. and the
monoclinic modification formed below about 1100° C, with a corresponding phase
conversion there can be a significant change in volume of the deposited ZrO2. As a
consequence, with increasing volume proportions of the ZrO2 there is a simultaneous increase
in the micro-crack density in the deposited ceramic layer.
In DE 28 25 009 C2 (U.S. Pat. No. 4,180,400), a hard metal body with a thin wear-resistant
surface layer of Al2O3 has been described and which is composed completely or at least 85%
of the K-modification and any possible remainder of the a-modification, forming surface
regions or patches at most 10 µm in size. The aluminum oxide layer can contain further
additions of titanium, zirconium and/or hafnium. To create this ceramic layer by the CVD
process, the gas mixture apart from AlC3. CO2, CO and H2 has also small amounts of 0.03 to
0.5% TiCl4 added to it. This addition, however, serves exclusively or nearly exclusively for
the formation of the K-Al2O3 phase.
A further CVD process for depositing A12O3 and/or ZrO2 using additional reagents, like
hydrogen sulfide, has been described in EP 0 523 021 B1 (U.S. Pat. No. 5,674,564).
DE 195 18 927 Al (U.S. Pat. No. 5,827,570) describes a coated cutting tool comprised of a
substrate of sintered carbide or ceramic with a wear-resistant composite ceramic coating
which has two different metal oxide phases, for example of Al2O3 and ZrO2 and in addition
thereto a doping agent selected from the group of sulfur, selenium, tellurium, phosphorus,
arsenic, antimony, bismuth or compounds of these elements. To produce this two-phase layer
by a CVD process, for example AlCl3 and ZrCl4. CO2 with H2 as a carrier gas, in addition to
an H2S gas, is passed over the substrate body at a temperature of about 700° to 1250° C. and
a pressure from 133 Pa to ambient pressure, whereby the two-phase layer with the doping
agent is deposited.
EP 0 786 536 Al (U.S. Pat. No. 5,985,427) describes a coated hard metal body with a 3 to 30
µm thick aluminum oxide coating which has been deposited by means of CVD and/or PVD
and contains 0.005 to 0.5 weight % chlorine. Optionally 0.5 to 10 weight % Zr and/or Hf and
1.5 to 15 weight % Ti can be contained in this coating.
EP 0 162 656 A2 (U.S. Pat. No. 4,746,563) describes a multilayer coating on a hard metal
substrate body which is comprised of an inner layer, which is composed of at least one
carbide, nitride, carbonitride, carbo-oxygen nitride, oxynitride, boron nitride or boron-
carbonitride of titanium, and an outer multilayer coating with a total thickness of 5 to 20 µm
and provided with an outer layer of a plurality of Al2O3 coatings with a respective thickness
of 0.01 to 2 µm and each comprised of an Al2O3 film in which titanium oxide has been
dissolved or which has been codeposited with at least 30 volume percent titanium oxide. The
layers are separated by intervening layers with respective thicknesses of 0.01 to 2 urn and
which each can comprise TiC, TiN, TiCN, TiCNO. TiNO, titanium oxides. Ti(B.N).
Ti(B.N,C), SiC,AlN or A1ON.
In WO 00/17 416 (U.S. Pat. No. 6,660,371), a composite material of a coated hard metal or
cermet base body has been described on which the single layer or a multilayer coating is
applied at least in the form of a 0.5 urn to 25 µm thick coating and preferably the outermost
phase is an Al2O3 phase containing a ZrO2 and/or HfO2 phase which in turn contains a third
fine dispersive phase consisting of an oxide, oxycarbide, oxynitride or oxycarbonitride of
titanium. The proportion of the third phase in the overall composition of this layer amounts to
0.2 to 5 mol %. To produce such a three phase layer, a CVD process with deposition
temperatures between 900° C. and 1000° C. is selected in which the gases required for the
deposit contain chlorides of the Al, Zr and I If, and in addition CO2, H2, CH4 and N2 or inert
gas under pressures of 10 to 100,000 Pa. The TiOx incorporated as the third phase has a
positive effect on the growth speed and on the particle sizes of the aluminum oxide and
zirconium or hafnium oxide. Preferably a coating temperature of 960° C. is selected in which
the ZrO2 is present in the monoclinic form. From the mentioned publication, therefore, hard
metal substrate bodies are known which have layer sequences TiN—Ti(C,N) and the
described three phase layer.
OBJECT OF THE INVENTION
It is the object of the present invention to provide a composite body which, when used as a
cutting insert, affords increased cutting affectivity as well as a longer useful life. Higher
cutting effectiveness is determined in terms of the desired high cutting speeds and increased
thicknesses of the chip removed. If possible such cutting inserts should be usable in so-called
dry cutting operations.
SUMMARY OF THE INVENTION
These objects are attained with a composite material having a base body carrying at least one
multiphase coating of the oxides of aluminum, zirconium and/or hafnium and of titanium (as
a three phase coating) and a single-phase layer or coating of Al2O3, ZrO2 or HfO2- In the
coating on the base body, therefore, there is. both at least one mutiphase oxide layer as well
as at least one single-phase oxide layer. The multiphase layer can, apart from the three-
mentioned oxide components, contain MgO and the single-phase layer can additionally
contain up to 1% of a titanium oxide proportion. According to a further feature of the
invention, however, at least two and preferably at least three layers are, provided of which
each is comprised of the mentioned multiphase layer of the oxides of Al, Zr, Ti and/or Al, Hf,
Ti and/or Al, Zr, Ti, Mg and/or Al, Hf, Ti, Mg, and a single-phase oxide layer of an oxide of
Hf, Zr or Al. Preferably at least three-phase or four-phase oxide layers are provided between
which respective single-phase oxide layers are disposed and whereby a single-phase oxide
layer also forms the outer cover coating. These layers have a fine grained lattice structure and
a uniform phase distribution and provide a high degree of thermal insulation. The base body
can also be comprised of a hard metal, a cermet, or steel or a ceramic material.
Between the substrate body and the first oxide layer which preferably is a multiphase oxide
layer is at least one layer of a carbonitride of titanium, hafnium, zirconium. This cover layer
can have a thickness between 2 to 15 µm, especially 3 to 8 mm.
According to a further feature of the invention it is possible to provide, between the
multiphase oxide layer and the single-phase oxide layer, preferably in a multilayer sequence
of the multiphase oxide layers and single-phase oxide layers between each of the mentioned
layers, one or more intermediate layers of titanium, hafnium or zirconium carbonitride.
These intervening layers have preferably a thickness between 0.2 and 3 urn, especially of 2
The total thickness of all multiphase oxide layers and all single-phase oxide layers preferably
lies between 6 and 20 urn especially at 10 urn. The difference of a single-phase oxide layer
can amount to 2 to 6 urn preferably 4 urn and the thickness of an individual single-phase
oxide layer can amount to 1 to 5 urn preferably 3 µm.
The multiphase coating is produced by a CVD process which is basically known from WO
00/17 416 or as the so-called middle temperature CVD process.
In a further embodiment of the invention, to eliminate tensile stresses or to increase
compressive stresses in the composite body, the composite body can be subjected to a
treatment with a blasting agent, the blasting agent being preferably composed of a hard metal
granulate which can have a substantially rounded grain configuration and a maximum grain
diameter of 200 µm and more preferably of a maximum of 100 µm.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
FIGS. 1 to 3 show respective diagrams which provide information with respect to the
improved life of the composite material according to the invention in cutting inserts by
comparison with the state of the art.
THIS INVENTION IS ILLUSTRATED IN THE ACCOMPANYING DRAWINGS
Further advantages of the invention are described in connection with an exemplary
embodiment. The drawing shows.
FIGS. 1 to 3 respective diagrams which provide information with respect to the improved life
of the composite material according to the invention in cutting inserts by comparison with the
state of the art.
' The test objects were in all three cases cutting inserts of the type CNMG120412-5. In all
three cases the substrate: body: was a hard metal (THM) but the coatings were different in the
three cases. In a first test series the work press was gray cast iron with a cutting speed of 450
m/min and a cutting depth of: 2. 5 mm and an advance of the cutting insert of 0.315 mm per
revolution. The first cutting body was comprised of a hard metal base body coated with a two
layer coating of TiCN—Al2O3 (as an outer layer). The life achieved was less than 2 min. A
significantly improved life was given with a two layer coating in which on a TiCN— cover
layer a three phase oxide layer according to WO 00/17 416 was applied comprised of
A clear improvement in the useful life still further can however be achieved with a cutting
insert which had a TiCN adjacent the substrate body and a six layer outer coating which was
comprised of three individual layers each of a three phase oxide coating and a single-phase
In a second test a gray cast iron workpiece with an extremely rough surface is machined by
turning whereby in comparison to the previously described test only the cutting speed was
reduced to 200 m/min. Based upon this cutting speed, there was obtained a useful life of 6
min for the cutting inserts with a TiCN—Al2O3 coating, of about 7 min for cutting inserts
with a TiCN—Al2O3/ZrO2/TiOx coating, and a useful life of 9 min for a cutting insert with
the coating of the invention in which by contrast with the previously described versions had a
three times alteration of a three-phase oxide layer of AlO2O3/HfO2/TiOx and the single-phase
oxide layer of HfO2. The above described cutting tests were carried out with so-called dry
As FIG. 3 shows, however, with use of a lubricant coolant, still higher useful lives can be
obtained. In the lathe turning of is grey cast iron at cutting speeds of 450 m/min. a cutting
depth of 2.5 mm, and a feed of 0.315 mm per revolution, the useful life of the cutting insert
with a TiCN—Al2O3 cutting amounted to about 4.5, min. the useful life of a cutting insert
with a coating according to WO 00/17 416 was about 6.5 min, whereas the coating according
to the invention resulted in useful lives of 10 or 12.5 min. Especially when HfO2 forms the
single-phase oxide layers, it is possible to obtain a still more substantial increase in the useful
life by comparison with the already improved life using ZrO2 as the single-phase oxide layer.
All coatings were applied by the so-called CVD-MT (middle temperature) process under the
same process conditions.
1. A composite material comprised of:
a base substrate body;
a first coating on the base body of a multiphase layer of titanium oxide and at least
two oxides from the group of aluminum, zirconium, and hafnium oxide and a second
single-phase layer on the first layer consisting of only one oxide of aluminum, zirconium,
and hafnium; and
a second coating on the first coating of a multiphase layer of titanium oxide and at
least two oxides from the group of aluminum, zirconium, and hafnium oxide and a second
single-phase layer on the respective first layer consisting of only one oxide of aluminum,
zirconium, and hafnium.
2. A composite material as claimed in claim 1 wherein each multiphase layer contains an
additional proportion of MgO or each single phase layer contains up to 1% of an
additional titanium oxide.
3. The composite material as claimed in claim 1 wherein the base body is composed of a
hard metal, steel, cermet or ceramic.
4. The composite material as claimed in claim 1 wherein between the substrate body and the
first multiphase oxide layer, at least one layer of TiCN, HfCN or ZrCN is provided which
has a thickness of 1 to 15 µm.
5. The composite material as claimed in claim 1 wherein between each multiphase oxide
layer and the respective single-phase oxide layer, one or more intermediate layers are
provided of TiCN, HfCN, or ZrCN, each of which has a thickness between 0.2 µm to 3
6. The composite material as claimed in claim 1 wherein the total thickness of all of the
multiphase oxide layers and all single phase oxide layers is 6 to 20 µm, the thickness of an
individual multiphase oxide layer being 2 to 6 µm, or the thickness of the individual single
phase oxide layer being 1 to 5 µm.
7. The composite material defined in claim 1, further comprising a third coating on the
second coating of a multiphase layer of titanium oxide and at least two oxides from the
group of aluminum, zirconium, and hafnium oxide and a second single-phase layer on the
respective first layer consisting of only one oxide of aluminum, zirconium, and hafnium.
TITLE; A COMPOSITE MATERIAL
A composite material comprised of: a base substrate body; a first coating on the base body of
a multiphase layer of titanium oxide and at least two oxides from the group of aluminum,
zirconium, and hafnium oxide and a second single-phase layer on the first layer consisting of
only one oxide of aluminum, zirconium, and hafnium; and a second coating on the first
coating of a multiphase layer of titanium oxide and at least two oxides from the group of
aluminum, zirconium, and hafnium oxide and a second single-phase layer on the respective
first layer consisting of only one oxide of aluminum, zirconium, and hafnium.
|Indian Patent Application Number
|PG Journal Number
|Date of Filing
|Name of Patentee
|KENNAMETAL WIDIA PRODUKTIONS GMBH & CO. KG.
|MUNCHENER STRASSE 125-127 45145 ESSEN,GERMANY
|PCT International Classification Number
|PCT International Application Number
|PCT International Filing date