Title of Invention

A METHOD OF FORMING A COATED CUTTING MEMBER

Abstract A coated metal substrate has at least one layer of titanium based hard material alloyed with at least one alloying element selected from the list of chromium, vanadium and silicon. The total quantity of alloying elements is between 1% and 50% of the metal content, the layer having a general formula of: (Ti100-a-b-cCraVbSic)CxNyO2.
Full Text COATED CUTTING TOOL, CUTTING MEMBER OR WEAR PART
FIELD OF THE INVENTION
The present invention is directed to providing protective coatings for general
applications including cutting tools, cutting members and cutting tool bits, wear parts,
thus extended working life.
BACKGROUND OF THE INVENTION
For machining work-pieces, by cutting, turning, milling, drilling and like,
cutting tools are used. The cutting tools remove surplus material, henceforth chips,
thereby shaping the work-piece. However, they are, themselves, worn away in the
process and require replacing. There is a correlation between hardness and wear
resistance. To ensure that chips are efficiently removed from the work-piece, whilst
ensuring long working life of the cutting tool, the cutting tool is required to be hard and
tough.
Hardness however may be correlated with brittleness however. Being both hard
and tough, composite materials consisting of hard ceramic particles in a metal matrix
are very popular choices for cutting tools. A number of such ceramic-metal composites
or cermets have been developed. The so-called hard metals consisting of tungsten
carbide particles in a metal matrix such as cobalt for example, are the materials of
choice for fabrication of cutting members for many applications. The term "cutting
member" includes, for example, inserts, cartridges, cutting plates, solid carbides cutting
heads, drills and end mills, etc.
The term "wear part" describes components used in applications where wear is a
recognized problem. Wear parts may be for various wear applications such as, for
example, machine parts, textile machine parts, ball bearings, roller bearings, moving
parts in heat exchangers, turbo loaders, gas-turbine, exhaust valves, nozzles,
manufacturing process dies for example for extrusion or wire drawing, punches,
blanking tools, hot forging and pressing, molds, shear blades, plunger rods for pumps,
plunger ball blanks, down hole pump check valve blanks, bushings, and other wear and
impact applications.
Wear parts are commonly made of carbon steel, austenitic, ferritic or
martensitic stainless steels, hot work tool steels, cold work tool steels, 51000 steels,
nickel and cobalt super alloys, and high speed steel.
It will be appreciated that the wear of cutting members and wear parts takes
place at their contact surfaces, and can be attributed to mechanical or friction type wear
or abrasion. Abrasion of cutting tools is often enhanced by chemical attack, such as
oxidization, for example, where the cutting tool material reacts with the surrounding
air, and / or the work-piece and / or coolant fluids and lubricants in wet machining
processes.
The downtime of cutting tools whilst the cutting members are replaced and of
other applications in which wear parts are replaced is costly. Much research is directed
to improving the wear resistance of such cutting tools and wear parts by application of
hard and / or chemical resistant coatings to increase their working life.
Indentation hardness is a measure of resistance to plastic deformation. There is
a strong correlation between indentation hardness and Mohs hardness, which indicates
the relative resistance of materials to scratching. In general, the harder a material, the
more abrasion resistant it is.
Since hardness is a measure of resistance to plastic deformation, unfortunately,
there is a general correlation between hardness and brittleness, and the harder a
material is, the more brittle it is, i.e. the more likely it is that stresses will be relieved by
crack propagation instead of by plastic deformation. In consequence of the above, it is
generally found that the more resistant a material is to gradual abrasion, the more it is
likely to be susceptible to brittle failure. It is often found that coatings that resist slow
wear tend to be susceptible to catastrophic failure modes such as thermal shock,
spalling, coating delamination and the like.
The general thrust of materials science research and surface engineering for
cutting tools and wear parts is to develop hard, tough (non-brittle) coatings that
increase the working life of cutting tools and wear parts by providing protection on the
surface against the main causes of wear: heat, chemical attack and abrasion.
Coatings may be formed on cutting members and wear parts by a range of
coating technologies that are generally classified as PVD (physical vapor deposition) or
CVD (chemical vapor deposition).
PVD gives very good properties and coating deposition rates are generally
equivalent than those of CVD techniques. It is a feature of PVD processes that
coatings can only be applied to line-of-sight areas of a substrate and cannot be applied
in holes and on shielded surfaces. Residual stresses from coating deposition tend to be
compressive and these stresses may cau333333se coatings to flake off. Because of
both the low deposition rates and the risk of coating failure due to the tensile internal
stresses and residual stresses from the deposition process as the coating thickness
increases, PVD is generally limited to thin coatings.
In contrast, CVD coatings are not restricted to line-of-sight deposition.
Relatively thick coatings of several microns may be deposited and, since residual
stresses may be tensile or compressive depending upon the substrate, the coatings are
less susceptible to spalling. Furthermore, deposition temperatures are typically rather
higher than those of PVD technologies. This facilitates the development of a diffusion-
induced interface between the coating and substrate which allows good adhesion to be
achieved. Indeed, good adhesion is one of the critical requirements for the coatings
applied to cutting members and wear parts and for more than 40 years, CVD (chemical
vapor deposition) has been used for coating cutting tools, cutting members, and wear
parts thereby improving their performance and effective working life.
It will be appreciated that some coatings and coating - substrate combinations
favor themselves to one or other deposition process and there are host of materials for
which only one or other process route is practicable.
Coatings of TiN, TiC and Ti(C,N) maybe deposited onto appropriate substrates
by reacting titanium tetrachloride with other gases, and removing the gaseous chlorides
thus formed:
TiCl4 + N2 + H2 ? TiN + Chlorides and other gases .
TiCl4 + CH4+ H2 ? TiC + Chlorides and other gases.
TiCl4 + N2+CH4 + H2 ? Ti(C,N) + Chlorides and other gases.
It will be appreciated that, over the years, other chemical vapor deposition
routes have become available for deposition of TiN, TiC and Ti(C,N), and the titanium
chloride processes described above are given by way of non-limiting example, only.
For example, MT (medium temperature) processing routes which tend to
produce different microstructures, often having columnar grain structure are popular.
For example:
CH3CN + N2 + H2 + TiCl4 ? MT Ti(C,N) + Chlorides and other gases.
With reference to Fig. 1, a scanning electron micrograph of the face of a typical
MT-Ti(C,N) coating as deposited by CVD is shown. The coating typically presents a
fine grained (1-3 micron) grain size on its face.
As the processing temperature increases, the substrate expands. On cooling, the
substrate and coating contract and, if the contraction is at different rates, residual
stresses result. It will be noted that the crack to the right of the micrograph is a typical
consequence of thermal mismatch between the coating and the substrate. By lowering
the process temperature, such cracking can be minimized. Where substrates contract
more than coating on cooling, such cracks tend to be closed.
Examination of a section through such a coating shows that the microstructure
consists of elongated crystals aligned through the coating thickness. This is due to the
growth of seeded crystals aligned such that the preferred direction of growth lies
through the coating thickness. Such coatings may be as much as 30 microns thick.
Cemented carbide made primarily of tungsten carbide optionally with the
addition of other carbides in a primarily cobalt binder is by far the most popular
substrate used for cutting tools. To prevent the cobalt binder reacting with the CVD
gases used for depositing a wear resistant coating such as TiCN, a thin (0.1 µm to 1.5
µm) protective layer of TiN is generally deposited prior to the TiCN layer. The
protective layer of TiN allows the tool bit to be subjected to the relatively harsh CVD
conditions required for deposition of TiCN without decarburizing the substrate thereof,
thereby minimizing the formation of undesirable, brittle ? phases (M12C, M6C where M
is Co and W) being formed near surface of the substrate 12. EP 0 440 157 and EP 0 643
152 describe deposition of TiN under TiCN in this manner.
TiCN is preferred to TiN in many cutting tool applications since TiCN has
better wear resistance and a lower coefficient of friction than TiN. Indeed, machining
with a TiN surfaced cutting tool may result in very high temperatures being generated
at which the coating may oxidize.
In the machining of hard materials, such as cast iron, for example, high
temperatures are generated and even TiCN, and TiC may interact with the work-piece
and / or with the cooling fluids and air.
One way of limiting workpiece - coating reactions is by alloying the coatings
with silicon which tends to form dense oxides. Alloying with chromium or vanadium
increases toughness and thus tool life when machining certain applications.
United States Patent Number US 6,007,909 to Rolander et al., entitled "CVD-
Coated Titanium Based Carbonitride Cutting Tool Insert" relates to a cutting tool insert
of a carbonitride alloy with titanium as the main component but also containing
tungsten and cobalt. The cutting tool insert is useful for machining, specifically for the
milling and drilling of metal and alloys. The insert is provided with a coating of at
least one wear resistant layer. The composition of the insert and the coating is chosen
in such a way that a crack-free coating in a moderate (up to 1000 MPa) compressive
residual stress state is obtained. It is alleged that the absence of cooling cracks in the
coating, such as that shown to the right of Fig. 2 and described hereinabove, in
combination with the moderate compressive stress, gives the tool insert improved
properties compared to prior art tools in many cutting tool applications. The alloying
of the coatings with Ti, Al, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Si or B to give solid
solutions is discussed. The coatings are characterized as being free from cooling
cracks, having a thickness exceeding 1 um and a compressive residual stress at room
temperature of 100-800 MPa. It will, however, be appreciated that using titanium
based carbonitride as the substrate for machine tool inserts is a serious limitation. For
regular cutting tools, WC-Co is the material of choice. Furthermore, although V, Cr
and Si are suggested as possible alloying elements for addition to coating layers during
CVD deposition, there is no further discussion of such coatings, and it does not appear
that they were ever produced.
There is thus still a need for improved Ti based hard metal coatings and the
present invention addresses this need.
SUMMARY OF THE INVENTION
In accordance with a first aspect of the invention, an improved coating -
substrate combination for a substrate such as a cutting tool, a cutting member, or a
cutting tool bit is presented.
In accordance with a second aspect of the invention, an improved coating -
substrate combination for a wear part is presented.
Improved coating comprises at least one layer of titanium based hard material,
such as TiCN, TiC, or TiN alloyed with at least one alloying element selected from the
list of chromium, vanadium and silicon, wherein the total alloying element content is
between 0.1% and 50% of the total metal content; the layer having a general formula
of(Ti100-a-b-cCraVbSic)CxNyO2, where x+y+z = 1 and a+b+c > 0.
Typically at least 70% of the metal content is titanium.
Preferably, between 0.1% and 30% of the total metal content comprises at least
one alloying element selected from the list of chromium, vanadium and silicon.
Optionally, between 0.1% and 30% of the total metal content in the layer is
chromium.
Optionally, between 0.1% and 30% of the total metal content in the layer is
vanadium.
Optionally, between 0.1% and 30% of the total metal content in the layer is
silicon.
Optionally, said coating further comprises at least one layer of alumina
deposited beneath or above the at least one layer of titanium based hard material.
The substrate may comprise a material selected from the list of high speed steel
alloys, tool steels, carbon steels, low alloyed steels, super alloys, super hard materials,
cermets, stainless steels, oxide and nitride ceramics, cemented carbides
Optionally the substrate is cemented carbide hard metal formed by sintering.
A third aspect of the invention is directed to providing a method of forming a
coated cutting tool.
A fourth aspect of the invention is directed to providing a method of forming a
coated wear part.
The method comprises the steps of:
(a) Obtaining a substrate fabricated from a selected material and having an
appropriate geometry;
(b) Placing the substrate in a chemical vapor deposition reaction chamber;
(c) Depositing an alloyed coating layer of (Ti100-a-b-cCraVbSic)CxNyOz where
x + y + z = 1 by chemical vapor deposition, and
(d) Removing the coated substrate from said vapor deposition reaction chamber.
In one processing route, the step of depositing an alloyed coating layer of
(Ti100-a-b-cCraVbSic)CxNyOz comprises: reacting a mixture of metal halides and organo-
metallics with gases selected from the list of nitrogen, hydrogen and methane.
Typically the metal halides are metal chlorides.
Typically the metal chlorides comprise titanium chloride and chlorides of
alloying metals selected from the list of chromium chloride, vanadium chloride and
silicon chloride.
Typically, at least 0.1% of the metal content of the coating is an alloying metal
selected from the list of chromium, vanadium and silicon.
Typically partial pressure of titanium halide is at least 50% of the total partial
pressure of metal chlorides in the CVD reaction chamber.
Preferably, the partial pressure of titanium halide is at least 70% of the total
partial pressure of metal chlorides in the CVD reaction chamber.
Optionally, partial pressure of chromium halide is between 0.1% and 30% of
the total partial pressure of metal chloride in the CVD reaction chamber.
Preferably, partial pressure of chromium halide is between 5% and 10% of the
total partial pressure of metal chloride in the CVD reaction chamber.
Optionally, partial pressure of vanadium halide is between 0.1 % and 30% of the
total partial pressure of metal chloride in the CVD reaction chamber.
Preferably, partial pressure of vanadium halide is between 5% and 10% of the
total partial pressure of metal chloride in the CVD reaction chamber.
Optionally, partial pressure of silicon halide is between 0.1% and 30% of the
total partial pressure of metal chloride in the CVD reaction chamber.
Preferably, partial pressure of vanadium halide is between 5% and 10% of the
total partial pressure of metal chloride in the CVD reaction chamber.
Typically, the method further comprises preparing the substrate by a process
including at least one of degreasing, sandblasting and washing.
Optionally, the method further comprises depositing at least one previous
coating layer prior to deposition of the alloyed coating layer.
Optionally, the method further comprises depositing subsequent coating layers
onto the alloyed coating layer.
Optionally and preferably the alloyed coating layer is deposited at medium
temperatures.
Optionally, between 0.1% and 30% of the metal content in the alloyed coating
layer is chromium.
Optionally, between 0.1% and 30% of the metal content in the alloyed coating
layer is vanadium.
Optionally, between 0.1% and 30% of the metal content in the alloyed coating
layer is silicon.
Optionally, between 70% and 99.9% of the metal content in the alloyed coating
layer is titanium and the alloyed coating layer comprises between 0.1% and 30% of
alloying metals selected from the list of chromium, vanadium and silicon, with the
alloyed coating layer comprising at least two of said alloying metals in said list.
Optionally, between 70% and 99.9% of the metal content in the alloyed coating
layer is titanium and the alloyed coating layer comprises between 0.1% and 30% of
alloying metals selected from the list of chromium, vanadium and silicon, with the
alloyed coating layer comprising all three of said alloying metals in said list.
As used herein, the term "cutting tools" may include any tool that is used to
remove material such as, for example metal, from a workpiece or to shape /
manufacture a workpiece.
As used herein, the term "cutting members" or "cutting tool bits" may include
any of the following: inserts, cartridges, cutting plates, solid carbides cutting heads,
drills and end mills, etc. for working workpieces.
As used herein, the term "working" includes processes such as drilling, milling,
cutting, turning and the like.
As used herein, the term "wear parts" may include parts such as molds, hot
work tool steels, cold work tool steels, valves, blades, moving parts components used in
applications where wear is a recognized problem. Wear parts may be for various wear
applications such as, for example, machine parts, textile machine parts, ball bearings,
roller bearings, moving parts in heat exchangers, turbo loaders, gas-turbine, exhaust
valves, nozzles, manufacturing process dies for example for extrusion or wire drawing,
punches, blanking tools, hot forging and pressing, molds, shear blades, plunger rods for
pumps, plunger ball blanks, down hole pump check valve blanks, bushings, and other
wear and impact applications.
BRIEF DESCRIPTION OF THE FIGURES
For a better understanding of the invention and to show how it may be carried
into effect, reference will now be made, purely by way of example, to the
accompanying drawings.
With specific reference now to the drawings in detail, it is stressed that the
particulars shown are by way of example and for purposes of illustrative discussion of
the preferred embodiments of the present invention only, and are presented in the cause
of providing what is believed to be the most useful and readily understood description
of the principles and conceptual aspects of the invention. In the accompanying
drawings:
Fig. 1 is a SEM micrograph of the surface of a typical, prior art, MT - Ti(C,N)
coating deposited by CVD;
Fig. 2 is a SEM micrograph showing a sectional view through the coating of
Fig. 1;
Fig. 3 is a schematic cross-section of one embodiment of the invention;
Fig. 4 is a flowchart summarizing a method for producing coatings of the
invention;
Fig. 5 is a SEM micrograph of the surface of an MT-(Ti-Si alloyed)C,N coating
as deposited by CVD;
Fig. 6 is a SEM micrograph showing a sectional view through the coating of
Fig. 5;
Fig. 7a is a photograph showing the edge of a cutting tool coated with a
MT-TiCN coating and used for dry machining;
Fig. 7b is a photograph showing the edge of a cutting tool coated with a
MT-TiCN coating alloyed with silicon, and used for dry machining under identical
conditions to those of Fig. 7a;
Fig. 8 is a bar chart showing comparative wear resistances of Ti(C,N) coatings
with increasing amounts of alloying metal therein due to the relative partial pressures of
0-10% silicon in the reactant vapor;
Fig. 9 is a SEM micrograph of an MT-(Ti-Cr)C,N coating as deposited by CVD
from above;
Fig. 10 is a SEM micrograph showing a sectional view through the coating of
Fig. 9;
Fig. 11 shows empirically determined effective working lives for identical
cutting tool insert substrates coated with Ti(C,N) and TiC coatings including increasing
amounts of chromium, due to relative partial pressures of 0-10% chromium in the
reactant vapor
Fig. 12 is a bar chart showing comparative wear resistances of MT- Ti(C,N),
HT- Ti(C,N), HT (Ti-lower chromium content)C,N and HT (Ti-higher chromium
content)C,N coatings respectively.
Fig. 13 is a SEM micrograph showing Ti(C,N) (layer A) with a characteristic
columnar structure, followed by a vanadium alloyed coating layer (Ti-V)C.N (layer B)
having a more equiaxed structure
Fig. 14a is a photograph showing the edge of a cutting tool coated with a
MT-TiCN coating (Sample l)and used for dry machining for 8 minutes;
Fig. 14b is a photograph showing the edge of a cutting tool coated with a
MT-TiCN coating that includes vanadium (sample 11), and used for dry machining
under identical conditions to those of Fig. 14a;
Fig. 15 is a bar chart showing comparative wear resistances of MT- Ti(C,N),
MT (Ti-lower chromium content)C,N and MT (Ti-higher chromium content)C,N
coatings respectively.
DETAILED DESCRIPTION OF THE INVENTION
Coating optimization is a multifaceted and unpredictable issue. Although there
have been breakthroughs in surface engineering the effect of different process
parameters on the microstructure of coatings is not fully understood. Additionally, the
complex interrelationships between the features of a coating's microstructure and its
tribology are not properly comprehended.
The present invention is directed to cutting members, such as cutting tool inserts
and the like, having novel coatings including at least one layer based on TiN, TiC or
Ti(C,N) but modified by the inclusion of appreciable amounts of alloying metals such
as one or more of chromium, vanadium and silicon. The novel coating layers thus
formed have the general formula (Ti100-a-b-cCraVbSic)CxNyOz where x + y + z = 1 and
display similar properties to TiN, TiC and Ti(C,N), i.e. are hard and tough, but, due to
the alloying metals, typically have improved corrosion resistance and are thus less
likely to react with the work-piece, cooling fluid or surrounding air.
The alloying elements may exist in solid solution and/or may be deposited as
secondary phase within TiC, TiN or Ti(C,N) grains or along grain boundaries
therebetween. Not only is the location of the dopant and the microstructural phases not
fully understood. The relative partial pressures of titanium containing and alloy
containing vapors in the reaction chamber during the CVD processes are known.
It is hypothesized that, as with simpler, better understood systems such as steels,
metallic dopants or alloying elements within the crystal lattice of the host coating
material, whether incorporated substitutionally or interstitially, tend to strain the lattice
and retard slip mechanisms. Similarly, inclusions rich in the alloying element, whether
deposited along grain boundaries or included within grains, will interfere with slip and
have a hardening effect. Inclusions also retard crack propagation, deflecting cracks and
thus tend to have a toughening effect. Consequently the alloyed coatings of the
invention are typically harder and / or tougher depending upon alloying type than
regular TiN, TiC and Ti(C,N) coatings of the prior art.
Whether or not the above hypothesis is true, experimental alloyed coatings with
varying amounts of alloying elements were compared with non-alloyed TiN, TiC and
Ti(C,N) coatings in various machining tests, under a variety of cutting tests on a variety
of substrates. The positive effects of depositing coatings of TiN, TiC and Ti(C,N)
alloyed with silicon, vanadium and chromium has been demonstrated.
The alloyed coating layers are deposited by chemical vapor deposition CVD,
and may be up to 20 µm thick. This is significantly thicker than coatings practically
achievable by PVD type technologies. Additionally, since the coating deposition is
initiated by a chemical reaction occurring on the substrate (or underlying coating)
surface, a strong chemical bond is formed, and the coating - substrate adhesion is
typically higher than that achievable by PVD.
One route for depositing TiN, TiC and Ti(C,N)respectively is by reacting the
titanium chloride with appropriate gases as follows:
TiCl4+N2+H2 ? TiN + Chlorides and other gases.
TiCl4+CH4+H2 ? TiC + Chlorides and other gases.
TiCl4+N2+CH4+H2 ? TiCN+ Chlorides and other gases.
There are also MT (medium temperature) processing routes which tend to
produce different microstructures, often having finer grain size, are popular. For
example medium temperature Ti(C,N) may be fabricated as follows:
CH3CN + N2 + H2 + TiCL, - MT Ti(C,N) + Chlorides and other gases.
Typically the deposition temperature is between about 720 - 950°C often called
medium temperature or 'MT' and 950 - 1100°C for high temperature 'HT' coatings.
It will be appreciated however, that, in addition to starting with titanium halide,
other reactions routes are possible and will suggest themselves to persons of the art.
In the fabrication of coatings of the type (Ti100-a-b-cCraVbSic)CxNyOz appreciable
amounts of the nitrides and carbides of chromium, vanadium and / or silicon are co-
deposited with TiN, TiCN and / or Ti(C,N). One way in which this co-deposition may
be achieved is by the controlled addition of the halides of chromium, vanadium and
silicon to the reaction chamber. Typically the chlorides of chromium, vanadium and
silicon are added. Control of the partial pressures of the reactants and the reaction
temperature provide a viable mechanism for affecting the composition and
microstructure of the coatings thus formed.
Using moderate fabrication temperatures of around 900°C or less lowers the
stresses between the coating and substrate and minimizes cooling cracking phenomena.
In general, the higher the deposition temperature, the more crystal growth is favored
over seeding of new crystals, and coarser, columnar coatings result.
For optimizing cutting tools and cutting tool bits for specific applications, the
coating layer of (Ti100-a-b-cCraVbSic)CxNyOz may be combined with other coatings. For
example, as explained hereinabove, TiN is not, itself, generally used as a wear resistant
coating for machining tool bits, however it is often advantageous to deposit a thin (0.1
µm to 1.5 µm) protective layer of TiN prior to deposition of
(Ti100-a-b-cCraVbSic)Cx, (Ti100-a-b-cCraVbSic)CyNz or (Ti100-a-b-cCraVbSic)CxNyOz since the
relatively harsh CVD conditions required for the deposition of the
(Ti100-a-b-cCraVbSic)Cx, (Ti100-a-b-cCraVbSic)CyNz or (Ti100-a-b-cCraVbSic)CxNyOz could
otherwise decarburize the substrate leading to the formation of undesirable, brittle r]
phases (M12C, MeC where M is Co and W) being formed near surface of the substrate
which could lead to catastrophic failure by the coating flaking off, for example.
Although Ti(C,N) is particularly good at resisting flank and nose wear of
cutting tool inserts, Al2O3 has been demonstrated as being generally more desirable on
the rake face. The coating layer of (Ti100-a-b-cCraVbSic)CxNyOz may advantageously be
covered with a subsequent layer of alumina, for example; each coating layer providing
effective protection against different types of wear.
With reference now to Fig. 3 a schematic illustrative section of a cutting tool or
cutting tool bit 10 is shown. Cutting tool bit 10 comprises a substrate 12 onto which
various intermediate layers 14,16,18 are deposited, and an alloyed coating layer 20 of
general formula (Ti100-a-b-cCraVbSic)CxNyOz deposited thereon. Subsequent layers 22,
24 may then be deposited onto the alloyed coating layer 20.
The substrate 12 may be fabricated from a high speed steel alloy containing, in
addition to iron and carbon, varying amounts of refractory metals such as chromium,
tungsten, molybdenum and titanium, for example. Substrate 12 may include a super-
hard material such as BN or diamond. Alternatively, substrate 12 may include a
ceramic such as SisN4, Al2O3, Al2O3/TiC, SiAlON, Al2O3/SiC whisker composite, and
the like. More commonly, substrate 12 is a cermet type composite such as TiC or TiN
in a metallic binder. Most typically, however, substrate 12 is a hard metal cemented
carbide type composite material, such as WC-Co or Cr3C2-NiCr that is generally
fabricated by sintering. Indeed, tungsten carbide (WC) cemented by a metal matrix,
usually Cobalt (Co) is the most popular choice for cutting tool bits.
Alloyed coating layer 20 has general formula (Ti100-a-b-cCraVbSic)CxNyOz and
typically between 50% and 99% of the metal within the coating is titanium. However,
a substantial amount, normally at least 0.1% and preferably at least 5%, of alloying
metal, such as Cr, V and /or Si is included within the alloyed coating layer 20.
Generally alloyed coating layer 20 includes between 0.1% and 30% of at least one
alloying metal selected from the list of chromium, vanadium and silicon. Alloyed
coating layer may include two or indeed all three of chromium, vanadium and silicon in
varying proportions. Typically no more than between 30% and most typically no more
than 10% (atomic percentages) of the total metal content is any one of the alloying
species.
With reference to Fig. 2, a method of fabricating cutting tool bits in accordance
with the present invention is now described. Firstly, a substrate fabricated from a
selected material and having appropriate geometry is obtained (Step 202). The
substrate is prepared by a process including at least one of degreasing, sandblasting and
washing. For example, the substrate may be cleaned in an ultrasonic bath of ethanol
and then sandblasted with #400 alumina grit, thereby ensuring an active surface that is
free from oxide scale, dirt and the like, for deposition of coatings thereupon (Step 204).
The substrate is placed into a chemical vapor deposition reaction chamber (Step 206).
Optionally, previous coating layers may be deposited, such as TiN for example (Step
208). An alloyed coating layer of (Ti100-a-b-cCraVbSic)CxNyOz is then deposited by
chemical vapor deposition (Step 210). This may perhaps be accomplished by reacting
a mixture of titanium chloride or other halide with halides of alloying metals, such as
chromium halide (typically chromium chloride), vanadium halide (typically vanadium
chloride) and silicon halide (typically silicon chloride) and gases such as nitrogen,
hydrogen and methane, for example.
Subsequent coating layers such as, for example, alpha, kappa or gamma
alumina, TiN, TiC, Ti(C,N), TiAlCN, TiAlCON, and or other (Ti100-a-b-
cCraVbSic)CxNyOz compositions may then be deposited thereupon (Step 212), with the
optimal coating lay up being dependent on specific tooling requirements.
Control of both the composition and the microstructure of alloyed coating layer
20 may be achieved by selecting reaction temperature and appropriate partial pressures
of the reaction gases during the chemical vapor deposition process. In general: (i) the
ratio of partial pressure of titanium halide to halide of alloying metal and (ii) the
fabrication temperature control the composition of the coating thus formed. In typical
deposition processes of the invention, the partial pressure of titanium chloride is
significantly more than the partial pressure of chromium, vanadium or silicon halide,
and the ratio of titanium chloride to other halides in the coating is usually between 1:1
and 99:1.
The general reaction leading to the coating layer of the invention is as follows:
TiCl4+N2 + (SiCl4, VCl3, CrCl2)+ H2 ? (Ti100-a-b-cCraVbSic)Ny+ Chlorides and other
gases.
TiCl4,+N2 + CH4 + (SiCl4, VCl3, CrCl2) + H2 ? (Ti100-a-b-cCraVbSic)CxNy+ Chlorides
and other gases.
TiCl4+ CH4 + (SiCl4, VCl3, CrCl2) + H2 - (Ti100-a-b-cCraVbSic)Cx + Chlorides and other
gases.
TiCl4+ CH4 + (SiCl4, VCl3, CrCl2)+ N2 + CO2 + H2 ? (Ti100-a-b-cCraVbSic)CxNyOz +
Chlorides and other gases.
TiCl4+ CH3CN + (SiCl4, VCl3, CrCl2)+ N2 + CO2 ? (Ti100-a-b-cCraVbSic)CxNyOz +
Chlorides and other gases.
For each desired alloying element, the partial pressure of the halide is typically
0.1% to 30% of the total metal halide partial pressure. Alloyed coating layer 20 will
typically be deposited at a temperature in the range of from about 720°C for (MT type
coatings) to 1100°C or so (for HT type coatings). The amounts of each metallic species
in the reactive atmosphere, i.e. the partial pressures of the reactant gases in the CVD
deposition chamber, are not the same as the relative percentages of the metals in the
coating. Nevertheless, control of the partial pressures during deposition does provide a
means of controlling the composition of the resulting coatings.
Proof of Concept Examples
To demonstrate proof of concept, thereby reducing the invention to practice, a
series of coatings was deposited onto a CNMG 432 GN cutting member, as widely used
for turning processes. The coated cutting members thus formed were used to machine a
range of materials in different manners under a range of conditions.
Example 1: Si alloying
After first depositing a protective layer of TiN to protect the substrate from the
harsh reactive gases, thereby preventing decarburization of the substrate surface, three
samples of Ti(CN) were deposited onto CNMG432GN hard metal substrates, to
provide coated cutting tools as described in table 1. The first coating was not alloyed.
During fabrication of the second coating, the partial pressure of Silicon chloride was
such that 5% of the metal ions in the reactive mixture were silicon. In the third coating,
10% of the metal content of the reactive gases was silicon.

Table 1 - compositions and thicknesses of coatings deposited onto CNMG 432 GN hard
metal substrates.
For quality control and optimization purposes, a Vickers diamond was indented
onto the coated face of the coated substrate, at an applied load of 20 Kg. The resultant
indents were examined under an optical microscope for signs of cracking and
delamination in and around the indent footprint. Where clear indents without cracking
resulted, the coatings were considered as being well bonded to the substrate.
Fig. 5 and Fig. 6 are SEM photomicrographs showing the surface and section of
coating number 3 of table 1.
The coated cutting tool inserts having coating layers as tabulated in table 1,
were directly compared with each other by being used to machine SAE 1045 steel and
gray Cast iron GG 25 under identical conditions.
For the continuous turning of steel SAE 1045, the cutting speed (Vc) was set to
250 m/min, the feed rate (f) was set to 0.20 mm/rev and the depth of cut (ap) was set to
2 mm. No coolant was used, and the cutting was performed dry, i.e. without using a
lubricant. The experimentally determined tool lives for Coating Nos. 1, 2 and 3 were
22, 30 and 30 minutes respectively.
For the continuous turning of gray Cast iron GG 25, the cutting speed (Vc) was
100 m/min, the feed rate (f) was set to 0.2 mm/rev, the depth of cut (ap) was 2 mm, and
the cutting was performed dry, without cooling fluids or lubricant. This time, the tool
lives for coatings 1, 2 and 3 were 4.5 minutes, 7 minutes and 3.5 minutes respectively.
These results are summarized in Table 2.

Table 2. Comparing empirically determined cutting tool lives for identical cutting tool
inserts, coated with Ti(C,N) coatings that included varying amounts of silicon.
It will be appreciated that by comparing the behavior of different coatings under
identical and realistic machining conditions in this manner, process parameters can be
varied one-factor-at-a-time and their influence on the performance of cutting tools
including such coatings can be accurately empirically assessed.
The worn cutting tool edges were examined in an attempt to quantify the types
of wear occurring. It appears that the main advantage of using Ti(C,N) coatings
alloyed with Silicon for machining SAE 1045 steel is that crater type wear is
significantly reduced. The effect is demonstrated by comparing Fig. 7a where the worn
surface MT-TiCN with 0% silicon is shown, to Fig. 7b showing the worn surface of the
MT-TiCN coating including a relatively large amount of silicon, i.e. when reactive
atmosphere during the deposition included 10% silicon. It will be appreciated that both
coatings were subjected to identical machining conditions for identical periods of time.
Example 2 - Medium and High Temperature (Ti-Si)C,N Coatings
A second comparative test was performed, wherein the performance of the
cutting tool bit coated with (Ti-Si)C,N deposited by medium temperature chemical
vapor deposition (sample 3 hereinabove) was compared with a cutting tool bit coated
with a multilayer coating having a thin (Ti-Si)C,N medium temperature CVD layer
covered with an alumina coating and coated with a TiCN or (Ti-Si)C,N high
temperature CVD layer (sample 4). 10% of the metal in the reactive atmosphere during
the CVD deposition was silicon, the rest was titanium.
A conventional TiCN coated cutting tool (sample 1) without silicon alloying
was used as a control. In the fabrication of all three of these cutting member samples, a
thin TiN barrier layer was first deposited onto the CNMG 432 GN substrate. The
thicknesses of the various layers are summarized in Table 3.

Table 3 - summarizing coating structure for three samples with varying alloyed silicon
contents and fabricated at medium and high temperatures
For the continuous turning of steel SAE 1045, the cutting speed (Vc) was set to
320 m/min, the feed rate (f) was set to 0.20 mm/rev and the depth of cut (ap) was set to
2 mm. No coolant was used, and the cutting was performed dry, i.e. without using a
lubricant. The effective tool lives for Coating Nos. 1, 3 and 4 were 7, 9 and 11.5
minutes respectively.
A comparative, empirical, interrupted machining test was performed on a
SAE 1060 steel work-piece. The cutting speed (Vc) was 93 m/min, the feed rate (f)
was set to 80 mm/rev and the depth of cut (ap) was 3 mm. Once again, the cutting was
performed dry, without lubricant or cooling fluid. This time, the tool lives for coatings
1, 3 and 4 were 7.5 passes, 6.5 passes and 16 passes respectively.
An interrupted chipping test was also performed on a SAE 4340 steel
work-piece. The cutting speed (Vc) was 210 m/min, the feed rate (f) was set to
0.5 mm/rev and the depth of cut (ap) was 2 mm. this time, however, wet machining was
used. The tool lives, defined as the length of the machined part to the exceeded cutting
edge wear, for coatings 1, 3 and 4 were 102 cm, 102 cm and 204 cm respectively.
The results of the comparative wear tests are summarized in Fig. 8 which are
normalized, i.e. showing the results of the 3 tests as percentage performance of coatings
3 and coating 4 compared with the performance of coating 1 (Ti-0% Si) C,N. The
results demonstrate effective working lives for identical cutting tool inserts coated with
Ti(C,N) coatings that included varying amounts of silicon due to the relative partial
pressures of 0-10% silicon in the reactant vapor.
The tests performed were:
Test A: continuous SAE 1045 - 320 dry / test 2;
Test B: strength, Walter test SAE 1060 - 93 dry / test 4; and
Test C: chipping test SA 4340 - 210 wet.
Although it will be appreciated that multilayer coatings must be considered as
systems, and the effect of the penultimate layer of alumina is expected to contribute to
the overall behavior of the coated tool bit, it can nevertheless be concluded that the (Ti-
Si)C,N coating deposited at high temperature enables a significantly improved cutting
tool performance with the work-piece, particularly for interrupted machining.

Table 4 - comparing effective tool lives for alloyed (Ti-Si)C,N coatings with Ti(C,N)
under empirical wear simulations
Example 3: Chromium alloying
Coatings of titanium alloyed with chromium MT- (Ti-Cr) C,N were deposited
onto hard metal substrates; specifically onto CNMG 432 GN cutting tool inserts as used
for turning. In coating 1, no chromium was present in the reactive atmosphere, but in
coatings 5 and 6, 10% of the metal in the reactive atmosphere during the CVD
deposition was chromium Table 5 summarizes the coating structures formed.

Table 5 - layer types and thicknesses for medium temperature and high temperature
chromium alloyed coatings
It is noted that coatings 5 and 6 had intermediate layer of medium temperature
TiCN deposited under the alloyed (titanium-chromium) carbide layer. In coating 5, the
upper layer was deposited at moderate temperature of approx. 900°C, whereas in
coating 6, the outer coating was deposited at a relatively high temperature of 1000°C.
Fig. 9 and Fig. 10 are SEM photomicrographs showing the surface and section
of coating 5, showing the double layer of MT- Ti(C,N) followed by MT-(Ti-Si)C,N.
As with the Ti(C,N) alloyed with silicon discussed above, the cutting tools with
coated alloyed with Chromium were used to machine work-pieces under various
conditions providing direct comparisons between the performance of the different
coatings under different machining conditions as follows:
Test 1: Continuous (wet) turning of SAE 316 L
For the continuous turning of steel SAE 316 L, the cutting speed (Vc) was set to
300 m/min, the feed rate (f) was set to 0.20 mm/rev and the depth of cut (ap) was set to
2 mm. This time a coolant was used. The performance of both (Ti-Cr)CN and (Ti-Cr)C
coated substrates (coatings 5 and 6) were 12 minutes and 14 minutes respectively, i.e.
20% and 40% better than the performance of TiCN without chromium, which lasted
only 10 minutes. Both these coatings were deposited from a mixture of reactive gases
including 105 Cr (percentage of metal in atmosphere by partial pressure).
Test 2: Interrupted dry machining test of steel SAE 1060
For the turning of steel SAE 1060, the cutting speed (Vc) was set to 93 m/min,
the feed rate (f) was set to 80 mm/rev and the depth of cut (ap) was set to 3 mm. No
coolant was used. The performance of both (Ti-Cr)CN and (Ti-Cr)C were 17.5 passes
and 23 passes respectively, i.e. 233% and 307% better than the performance of TiCN
which survived only 7 1/2 passes.

Table 6 - showing the effect on wear on the addition of chromium to Ti based coatings.
A further series of coatings were deposited to determine the effects of alloying TiC and
TiCN with varying amounts of chromium and the effect of process temperature. The
thickness and materials of the coating layers are summarized in Table 7.

Table 7 summarizing the thickness and materials of the coating layers of TiC and TiCN
alloyed with chromium.
The coated cutting tool inserts were used to wet machine SAE 4340 steel in an
interrupted fashion resulting in chipping type wear.
Fig. 11 is a bar chart showing comparative wear resistances of Ti(C,N) coatings
1 and coatings 5 and 6 alloyed by the co-deposition and inclusion of chromium from a
reactive gas mixture including 10% chromium by metal content. The cutting speed
(Vc) was set to 210 m/rnin, the feed rate (f) was set to 0.15 mm/rev and the depth of cut
(ap) was set to 2 mm. the machining was performed using a coolant. The tool life was
defined as the length of the machined part to the exceeded cutting edge wear, and,
using this definition, the Ti(C,N) coating (coating 1) had a tool life of 1.36 cm. Merely
fabricating the Ti(C,N) coating at a higher deposition temperature (coating 7) increased
the tool life to 1.53 cm which is a 12.5% increase, despite the overall coating thickness
being 10% thinner.
The tests performed were
Test A: continuous SAE 316 L - 300 - wet; and
Test B: strength, Walter test SAE 1060 - 93 dry.
Alloying with less and more chromium (partial pressures of reactive gases - 5%
Cr and 10% Cr respectively) increased the tool life to 1.7 cm, i.e. a 25% increase,
despite the overall coating thickness being less, see Fig. 12 which shows comparative
wear resistances (e.g. empirically determined effective working lives) of MT Ti(C,N),
HT Ti(C,N), HT (Ti-Cr)C,N with less chromium, i.e. 5% partial pressure of chromium
in the chemical vapor of the reactive gas, and HT (Ti-Cr)C,N coatings with more
chromium, i.e. 10% partial pressure of Chromium containing gas in the reactive
mixture. The coating Nos. 7, 8, and 9 were compared to coating No. 1 and the test C
performed was and interupted chipping test SA 4340 - 210 wet test.
Example 4: Vanadium alloying
Once again, coatings were deposited onto WC-Co cutting tool substrates.
CNMG 432 GN hard metal substrate for turning was again used for all the experiments.
Table 8 showing coating dimensions and compositions for vanadium alloyed coatings.
With reference to Fig. 13, a SEM micrograph of a cross section through sample
11 is given. Note the moderate temperature coating Ti(C,N) coating (layer A) which
has a columnar microstructure, followed by a second coating (layer B) containing
significant, if indeterminate amounts of vanadium and having an equiaxed crystalline
structure.
Test 1: Continuous (wet) turning of SAE 1045
A workpiece of Steel SAE 1045 was machined under continuous turning
conditions by a Ti(C,N) coated cutting tool (coating No. 1) and by similar cutting tools
coated with similar coatings but alloyed by the co deposition and inclusion of vanadium
from a reactive gas mixture including 5% (coating no. 10) and 10% (coating no. 11) of
vanadium by metal content.
Fig. 15 is a bar chart showing the comparative wear resistances of the three
coatings. The cutting speed (Vc) was set to 250 m/min, the feed rate (f) was set to
0.2 mm/rev and the depth of cut (ap) was set to 2 mm. No coolant was used. The tool
life was given in time to failure, and using this definition, the Ti(C,N) coating (coating
1) had a tool life of 18 minutes. Coating 10 with a low vanadium content had a tool life
of 20 minutes and coating 11 with a higher vanadium content, had a life of 19 minutes.
It appears therefore, that alloying with vanadium increases the life of cutting tools
under these machining conditions. The tests performed were
Test A: continuous SAE 1045 - 250 m dry / test 2;
Test B: strength, Walter test SAE 1060 - 93 dry / tests 4 and 5; and
Test C: chipping test SA 4340 - 210 wet.
The coatings were examined after 8 minutes of continuous turning. Fig. 14a is
an optical microphotograph showing the worn surface of a MT TiCN coated cutting
tool (sample 1) and Fig. 14b is an optical microphotograph showing the worn surface of
the MT (Ti-V)CN coating that included a relatively large amount of vanadium, i.e.
when the reactive atmosphere during the deposition included 10% chromium halide
vapors by weight (sample 11). It will be appreciated that both coatings were subjected
to identical machining conditions for identical periods of time. Nevertheless, the crater
wear is significantly reduced with the vanadium alloyed coating indicating that
Vanadium alloying of MT TiCN reduces crater wear.
Test 2: Interrupted dry machining test of steel SAE 1060
For the turning of steel SAE 1060, the cutting speed (Vc) was set to 93 m/min,
the feed rate (f) was set to 80 mm/rev and the depth of cut (ap) was set to 3 mm. No
coolant was used. Coating 1 (TiCN) had a working life of 6 passes. Coating 10 had a
working life of 11 passes and coating 11 had a working life of 18 passes. Clearly the
alloying with vanadium provides significant benefits in interrupted machining of this
type.
An interrupted chipping test was also performed on a SAE 4340 steel
work-piece. The cutting speed (Vc) was 210 m/min, the feed rate (f) was set to
0.15 mm/rev and the depth of cut (ap) was 2 mm. This time, however, wet machining
was used. The tool lives, defined as the length of the machined part to the exceeded
cutting edge wear, for coatings 1, 10 and 11 were 102 cm, 85 cm and 90 cm
respectively. It appears, therefore, that for interrupted chipping, the vanadium alloying
was not advantageous.
The results of the comparative wear tests are summarized in Fig. 15 which are
normalized, i.e. showing the results of the 3 tests as percentage performance compared
with the performance of coating 1.
Examples of Substrate Coating Combinations for Wear Parts
The following examples utilize the coatings and methods of coating disclosed
above upon different substrates by way of example that are intended for use as wear
parts.
Example 5: Carbon steel base low alloyed substrate coating combination
A coating for a carbon steel base low alloyed substrate, for example AISI
51100, comprising a first layer of HT-TiVCrN or MT-TiVCrN. One or more layers of
any of coatings 2-11 described above may be deposited upon the first layer. These
coatings are corrosion resistant and significantly reduce decarburization. The improved
temperature shock resistance of this coating allows the coating and hardening oil
hardening and or vacuum high pressure quenching steels. These coatings are excellent
for applications such as, for example, ball bearings, roller bearings, type 51000 steels,
or textile machine parts.
Example 6: Hot work tool steel substrate coating combination
Example 6A A coating for a hot work tool steel substrate, for example AISI
HI 3 with a first layer of HT-TiCN. One or more layers of any of coatings 2-11
described above may be deposited upon the first layer, particularly TiVCN coatings.
These coatings are excellent for applications such as, for example, extrusion and wire
drawing AlCu alloys, and steels.
Example 6B A coating for a hot work tool steel substrate, for example AISI
H13 with a first layer of HT-TiVCRN or MT-TiVCRN and a second layer of MT-
TiCN. One or more layers of any of coatings 2-11 described above may be deposited
upon the second layer. A top layer of CrTiSi(C,N) in combination with a columnar
MT-Cr layer is excellent for tougher tools with improved heat checking resistance, and
shock resistance especially for applications such as hot forging and pressing.
Example 7: Stainless steel, Nickel and Cobalt super alloys substrate coating
combination
A coating for austenitic, ferritic and martensitic stainless steels, for example
A1S1316 or A1S1420, nickel and cobalt super alloys with a first layer of HT-TiVCrN or
MT-TiVCrN followed by a second layer of MT-TiCN. One or more layers of any of
coatings 2-11 described above may be deposited upon the second layer. These
coatings are excellent for substrates for which alumina, especially thick layers of
alumina, is difficult to apply. A layer of HT-Ti-Cr-Si-N significantly improves
resistant to adhesive wear, high temperature wear, and oxidation. These coatings are
excellent for applications such as, for example, moving parts in heat exchangers
(fretting), turbo loader, gas-turbine applications.
Example 8: Cold work tool steels or High speed steel substrate coating combination
A coating for cold work tool steels, for example AISID2 and for high speed
steel, for example AISI M2 with a single layer of TiVCN. These coatings are excellent
for applications such as, for example, cold forming of stainless steel. One or more
layers of any of coatings 2-11 described above may be deposited upon the first layer.
Although it will be appreciated that multilayer coatings must be considered as
systems, and the effect of the penultimate layer of (Ti-0%V)C,N is expected to
contribute to the overall behavior of the coated tool bits, it can nevertheless be
concluded that alloying with vanadium significantly improved cutting tool
performance, particularly for interrupted machining.
The effect of the vanadium alloying of MT-TiCN is to change the coating grain
structure to a less columnar grain structure. The biggest gains appeared to be a
reduction of crater wear in continuous turning of Carbon Steel and an increase in
coating and cutting edge strength.
Alloying with two or more metals selected from the list of silicon, chromium
and vanadium and perhaps even more exotic materials such as molybdenum are
expected to show similar properties. The effect is not expected to be additive, but, as
with the long researched and far better understood alloyed iron-carbon system (steels),
appropriate amounts of different alloying elements are expected to provide
improvements in the properties such as hardness, corrosion resistance, etc., giving a
longer working life to the cutting tools thus coated.
Generally, for reasons discussed above, alloying TiC, TiN and Ti(C,N) coatings
with a second metal, such as silicon, vanadium or chromium will, in general, increase
the toughness and other properties such as hardness, oxidation resistance, etc. of the
coating to increase the life of the coated parts.
It has been demonstrated hereinabove that the addition of alloying elements
such as Si, Cr, and V to Ti(C,N) type coating layers for cutting tool bits enhances the
effective tool life of machine tools operating under a wide range of machining
processes on a wide range of work-piece materials. It has further been demonstrated
that such alloy coatings may be deposited by CVD.
Optimization for specific purposes is crucial. One factor at a time experimental
methods are difficult to perform for complex processes but standard R&D techniques
for quantifying the effect of incremental changes to process parameters, specifically
deposition temperatures and the relative proportions of the various elements in the
coating are expected to lead to improved coatings.
Thus the scope of the present invention is defined by the appended claims and
includes both combinations and sub combinations of the various features described
hereinabove as well as variations and modifications thereof, which would occur to
persons skilled in the art upon reading the foregoing description.
WE CLAIM:
1. A coated metal substrate comprising a coating comprising at least one layer of
titanium based hard material is alloyed with at least one alloying element
selected from the list of chromium, vanadium and silicon, wherein the total
alloying element content is between 0.1% and 50% of the total metal content;
the layer having a general formula of (Ti100-a-b-cCraVbSic)CxNyOz, where x+y+z
=1 and a+b+c > 0 with the proviso that y+z > 0 when a+c = 0 and whereby the
coating is a CVD coating deposited from about 720°C to about 1100°C.
2. The coated metal substrate of claim 1, wherein 70% of the total metal content in
the at least one layer comprises titanium.
3. The coated metal substrate of claim 1, wherein between 0.1% and 30% of the
total metal content in the at least one layer is selected from the group
comprising chromium, vanadium and silicon.
4. The coated metal substrate of claim 1, wherein the coating further comprises at
least a first layer of alumina.
5. The coated metal substrate of claim 1 wherein the substrate comprises a
material selected from the group comprising hard metal, high speed steel alloys,
super hard materials, cermets, cemented carbides, TiC, TiN, WC-Co, carbon
steels, low alloyed steels, austenitic stainless steels, ferritic stainless steels,
martensitic stainless steels, tool steels, nickel and cobalt super alloys, oxide
ceramics and nitride ceramics.
6. A method of forming a coated cutting member or a coated wear part,
comprising the steps of:
(a) Obtaining a substrate fabricated from a selected material and having an
appropriate geometry;
(b) placing the substrate in a chemical vapor deposition reaction chamber,
and
(c) depositing an alloyed coating layer of (Ti100-a-b-cCraVbSic)CxNyOz, where
x+y+z = 1 and a+b+c > 0 with the proviso that y+z > 0 when a+c = 0, in
the range of 720°C to 1100°C by chemical vapor deposition by reacting
a mixture of metal chlorides and gases, the gases are selected from the
list of nitrogen, hydrogen and methane and the metal chlorides are
selected from the list of titanium tetrachloride,, chromium chloride,
vanadium chloride and silicon chloride.
7. The method of claim 6, wherein step (c) further comprises vapors of at least one
organic compound selected from the list of organic compounds containing
carbon, organic compounds containing nitrogen, and organic compounds
containing oxygen.
8. The method of claim 6, wherein partial pressure of chromium chloride is
between 0.1% and 30% of total partial pressure of metal chloride in the CVD
reaction chamber.
9. The method of claim 6, wherein partial pressure of vanadium chloride is
between 0.1 % and 30% of total partial pressure of metal chloride in the CVD
reaction chamber.
10. The method of claim 6, wherein partial pressure of silicon chloride is between
0.1% and 30% of total partial pressure of metal chloride in the CVD reaction
chamber.
11. The method of claim 6, further comprising: depositing at least one previous
coating layer prior to deposition of the alloyed coating layer.


A coated metal substrate has at least one layer of titanium based hard
material alloyed with at least one alloying element selected from the list of
chromium, vanadium and silicon. The total quantity of alloying elements
is between 1% and 50% of the metal content, the layer having a general
formula of: (Ti100-a-b-cCraVbSic)CxNyO2.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=k4zU7JsT0tsi/merXClYFw==&loc=wDBSZCsAt7zoiVrqcFJsRw==


Patent Number 280044
Indian Patent Application Number 3640/KOLNP/2009
PG Journal Number 06/2017
Publication Date 10-Feb-2017
Grant Date 08-Feb-2017
Date of Filing 19-Oct-2009
Name of Patentee IHI IONBOND AG
Applicant Address INDUSTRIESTRASSE 211, 4600 OLTEN,Switzerland
Inventors:
# Inventor's Name Inventor's Address
1 LANDAU, YEHEZKEAL 95 HERTZEL STREET, 22447 NAHARIYA, ISRAEL
2 LAYYOUS, ALBIR A. P.O. BOX 385, 25140 ME'ILYA, ISRAEL
3 STRAKOV, HRISTO MUEHLETALWEG 11, CH-4600 OLTEN, SWITZERLAND
4 BONETTI, RENATO HALDENSTR. 16, CH-4652 WINZNAU, SWITZERLAND
PCT International Classification Number C23C28/00; C23C28/04; C23C30/00
PCT International Application Number PCT/IL2008/000461
PCT International Filing date 2008-04-03
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 182741 2007-04-23 Israel