Method for producing a coated object and coated object

Abstract

A method for producing a coated object (10) wherein the method comprises the steps of providing a substrate (12) in a reaction chamber and depositing an anti-wear layer (16) by physical vapor deposition on a surface (14) of the substrate (12) wherein a target is provided in the reaction chamber, the target containing at least a first transition metal Ma in order to produce a Ma2C phase in the anti-wear layer, the first transition metal is a transition metal from Group 5 or Group 6 of the Periodic Table, and wherein the proportion of Ma in the Ma2C phase in the antiwear layer (16) is at least 60 at%, based on the total amount of transition metals in the antiwear layer (16). Furthermore, a coated object (10) is indicated.

Description

Technical Field

[0001] The invention relates to a method for producing a coated object and to a coated object. Background Art

[0002] In order to increase the resistance of objects such as cutting and machining tools, it is common practice to apply a coating to the surface of the corresponding object, which coating is characterized in particular by a high hardness. For example, physical vapor deposition (PVD) can be used to deposit coatings of titanium aluminum nitride (TiAlN), tungsten carbide (WC) or titanium carbide (TiC). It is also known to use amorphous carbon (also called "diamond-like carbon", DLC) as a high-hardness coating. However, such coatings are limited in terms of the achievable layer thickness and layer adhesion.

[0003] Coatings made of so-called "superhard" materials with a plastic hardness greater than 40 GPa are also known, for example titanium diboride (TiB2). However, coatings made of superhard materials tend to be brittle, which has a negative impact on the life of the coated objects to which they are applied due to the tendency of the coatings to flake off. Summary of the invention

[0004] It is an object of the present invention to provide a method for producing a coating which combines high hardness, low intrinsic voltage and good layer adhesion, and an object having such a coating.

[0005] The object is solved by a method for producing a coated object, wherein the method comprises the following steps:

[0006] - providing a substrate in a reaction chamber, and

[0007] - Depositing an anti-wear layer on the surface of a substrate by physical vapor deposition, wherein a target containing at least a first transition metal Ma is introduced into a reaction chamber to produce a Ma2C phase in the anti-wear layer, wherein the first transition metal is a transition metal from the fifth group or the sixth group of the periodic table, and wherein the proportion of Ma in the Ma2C phase in the anti-wear layer is at least 60 atomic % based on the total amount of transition metal in the anti-wear layer.

[0008] The invention is based on the basic idea of ​​applying an anti-wear layer having a metal carbide phase with a high metal content, i.e. a dimetallic carbide phase (Ma2C phase) as its main component. It has been found that such a phase is characterized by a particularly high hardness and can be generated in a targeted manner by a PVD method using a target in a reaction chamber as a cathode, the target containing or consisting of the corresponding transition metal Ma and thus being able to release the transition metal Ma by a corresponding PVD method.

[0009] According to the present invention, a metal-carbide phase produced by an equilibrium process such as TiC or WC through sintering and / or chemical vapor deposition (CVD) is no longer used as the main component in the anti-wear layer. This of course does not exclude the possibility that a small amount of such a phase may be present in the anti-wear layer.

[0010] In this way, a coated object can be obtained that combines high hardness, low intrinsic voltage, and excellent adhesion to the metal substrate due to the process control according to the present invention.

[0011] The substrate is specifically a hard metal, cermet, or tool steel. Hard metals include, for example, metal carbides, where the metal is selected from the group consisting of tungsten, titanium, tantalum, niobium, and mixtures thereof, and a binder, such as a cobalt-based binder.

[0012] The coated object is specifically a cutting tool, such as a cutting tool for chip removal machining.

[0013] According to the present invention, the target contains a transition metal of Group 5 or Group 6 of the periodic table (designated as "Ma"). As contemplated by the present invention, such transition metals are capable of forming a high-hardness Ma2C phase. This is not possible for other metals such as titanium.

[0014] For example, the target contains vanadium, niobium, tungsten, or molybdenum. Thus, the Ma2C phase can be a V2C, Nb2C, W2C, or Mo2C phase.

[0015] In principle, the type of PVD method is not further limited as long as the desired Ma2C phase can be specifically generated. For example, the anti-wear layer is applied by magnetron sputtering or an arc method.

[0016] The anti-wear layer is specifically applied by magnetron sputtering. Magnetron sputtering enables rapid layer growth during the deposition of the anti-wear layer while maintaining a constant pressure in the reaction chamber.

[0017] Specifically, when depositing the anti-wear layer, the argon gas flow through the reaction chamber is 200 to 600 mL n / min, preferably 300 to 500 mL n / min, where mL n / min herein and hereinafter represents the volume of the corresponding gas per minute under standard conditions (273.15 K and 1013.25 hPa).

[0018] The wear-resistant layer is preferably applied by HIPIMS (High Power Impulse Magnetron Sputtering), where power pulses are applied to the target and voltage pulses are applied to the substrate, and where the application of the power pulses and the voltage pulses has a time delay. Compared to other magnetron sputtering methods, HIPIMS is characterized by a further increase in the power density of the material removed from the target and a high degree of ionization. By using power pulses, each pulse can have a maximum power that can be higher than what a permanently applied electric field might have, since the discharge occurs within a short time interval. The target can cool between the respective power pulses.

[0019] The power pulses are used to remove material from the target placed in the reaction chamber and release it into the plasma present in the reaction chamber. The voltage pulses applied to the rotating table with the object or substrate to be coated cause the ionized material to accelerate from the plasma towards the substrate, such that the material is deposited on the substrate placed in front of it in the form of a wear-resistant layer.

[0020] Thus, each power pulse at the target assigns a voltage pulse at the substrate or substrate holder. The time delay between the power pulse and the voltage pulse refers to the respectively assigned power pulse and voltage pulse. This is also referred to as a "synchronous pulse".

[0021] The time delay enables a time-point specific adjustment of the proportion of metal ions in the plasma in the reaction chamber at the time when the ions accelerate away from the plasma towards the substrate, and thus to produce a desired composition in the deposition phase. This results in a particularly flexible process design. By way of example, reference is made to the method for coating substrates using HIPIMS as described in EP 2 761 050 B1.

[0022] The time delay is specifically a time delay of 30 to 100 microseconds, preferably 40 to 80 microseconds. A shorter time delay may lead to an increase in the amount of argon ions incorporated into the wear-resistant layer, which will increase its intrinsic compressive voltage, while a time delay exceeding 100 microseconds may lead to a decrease in the amount of metal ions.

[0023] Furthermore, compared to other PVD methods, when using HIPIMS to deposit the wear-resistant layer, the proportion of argon incorporated into the growth layer is reduced and the proportion of implanted metal ions is increased. In this way, the intrinsic voltage of the wear-resistant layer is further reduced without having to worry about disadvantages with respect to the achievable plastic hardness.

[0024] The target power (i.e., the cathode power in the HIPIMS process) is specifically 5 to 12 kW, preferably 6 to 10 kW.

[0025] The bias voltage between the target and the substrate is in the range of 50 to 250 V, preferably 120 to 200 V.

[0026] To supply carbon required for forming the Ma2C phase to the reaction chamber, an additional graphite cathode can be used to supply carbon to the reaction chamber during the deposition of the antiwear layer.

[0027] The operation of the graphite cathode is synchronized with the target pulse of the target corrosion material, so that the desired ratio of the transition metal to carbon is achieved in the plasma, thereby producing the desired composition of the phase to be deposited on the substrate. In other words, co-sputtering is performed in this variant.

[0028] Specifically, the power of the graphite cathode is 1 to 5 kW. Therefore, the power of the graphite cathode is particularly lower than the target power.

[0029] In addition to or as an alternative to using the graphite cathode, the reaction chamber can be flushed with a carbon-containing reactive gas such as acetylene to supply carbon during the deposition of the antiwear layer.

[0030] For example, when depositing the antiwear layer, the flow rate of the carbon-containing reactive gas through the reaction chamber is 10 to 100 mL n / min, preferably 20 to 50 mL n / min.

[0031] The carbon-containing reactive gas (such as acetylene) dissociates in the plasma present in the reaction chamber, where carbon ions required for forming the Ma2C phase are generated. In other words, reactive sputtering is performed in this variant.

[0032] To further simplify the design and operation of the reaction chamber, either a graphite cathode is provided or the reaction chamber is flushed with a carbon-containing reactive gas during the deposition of the antiwear layer.

[0033] The reaction chamber is heated to a temperature in the range of 100°C to 600°C, preferably 300°C to 500°C. At temperatures below 100°C, the layer adhesion of the antiwear layer to the substrate may be insufficient. Temperatures above 600°C cause a continuous increase in energy requirements and may lead to graphite precipitation in the antiwear layer, which will result in a reduction in hardness.

[0034] In the reaction chamber, a pressure of 0.1 to 0.5 Pa, preferably 0.2 to 0.45 Pa, is set during the deposition of the antiwear layer. Pressures less than 0.1 Pa may result in insufficient layer growth rate, while pressures greater than 0.5 Pa reduce the mean free path length of the ions and thus cause too many pulses to be input into the growing layer.

[0035] The target may further include a second transition metal Mb that forms a nitride, which is used to produce a nanocrystalline structure containing a major phase and a minor phase during the deposition of the antiwear layer, where the major phase is the Ma2C phase and the minor phase is a cubic nitride phase or a carbonitride phase containing the second transition metal Mb.

[0036] The target may contain a first transition metal Ma and a second transition metal Mb in alloy form. For example, the target consists of an alloy of the first transition metal Ma and the second transition metal Mb.

[0037] The secondary phase reduces the crystallite size in the primary phase (i.e., the crystallites of the Ma2C phase), refines the microstructure of the antiwear layer, and can further reduce the growth-related intrinsic voltage. The nanocrystalline structure should be understood to mean that the size of the corresponding crystallites of the structure is 10 nm or less.

[0038] In this way, a so-called nanocomposite structure is produced in the antiwear layer, in which a nitride phase and / or a carbonitride phase coexists with a carbide phase, such as Ma2C / MbN or Ma2C / MbCN.

[0039] The use of the secondary phase in the antiwear layer further increases its chemical resistance, which has a particularly advantageous effect on the service life of the coated object when processing ferrous substrates.

[0040] The second transition metal molybdenum is a strong nitride former. Preferably, the second transition metal Mb is selected from the group consisting of transition metals of Group 4 of the periodic table (also known as the "titanium group") vanadium, chromium, and combinations thereof.

[0041] In order to supply the nitrogen gas required to construct the secondary phase to the reaction chamber, the reaction chamber can be flushed with a nitrogen-containing reactive gas (e.g., with nitrogen gas) to supply nitrogen gas during the deposition of the antiwear layer.

[0042] The flow rate of the reactive gas containing nitrogen gas can be 10 to 100 mL n / min, preferably 20 to 50 mL n / min.

[0043] Regardless of whether the Ma2C phase or the secondary phase is deposited at a given time during the deposition process, the mixture of the two phases can be adjusted according to the target power, the graphite cathode power, the flow rate of the carbon-containing reactive gas, and / or the flow rate of the nitrogen-containing reactive gas.

[0044] In one variant, the antiwear layer is the only coating applied to the substrate. This makes the coating process particularly simple, and the coating process already has excellent power characteristics of the coated object due to the nature of the specifically generated Ma2C phase and optionally the secondary phase.

[0045] In another variant, a top layer of MaC, MbN and / or MbCN is applied to the antiwear layer, where Ma represents a first transition metal Ma of interest and Mb represents a second transition metal Mb of interest. In other words, a top layer of a "conventional" transition metal carbide, transition metal nitride or transition metal carbonitride can be applied. Also in this case, the desired composition of the top layer can be achieved by appropriately selecting the process parameters, in particular by adjusting the power of the graphite cathode, the flow rate of the reactive gas containing carbon and / or the flow rate of the reactive gas containing nitrogen.

[0046] In another variant, a pure carbon top layer can be applied by shutting off the target (i.e., the target made of a transition metal). This can further reduce the tendency of the coated object to friction.

[0047] The coated object preferably does not contain alternating layers. In other words, no alternating layers are applied to the substrate or the antiwear layer. Here, an alternating layer should be understood as a sequence of at least three layers, where at least two layers that are chemically different from each other repeat in a regular pattern starting from the substrate. Thus, complex deposition methods can be avoided, while the desired resistance and hardness of the coating are continued to be achieved using the Ma2C phase in the antiwear layer.

[0048] The antiwear layer can be applied with a thickness in the range of 1 to 10 μm, preferably 3 to 6 μm. The desired layer thickness can be achieved quickly and with relatively little material. In the case of such layer thicknesses, an antiwear layer with a plastic hardness of at least 30 GPa, preferably at least 35 GPa, can be obtained, which at the same time has high toughness and thus a low chip formation tendency.

[0049] Of course, the method according to the invention can include additional method steps.

[0050] For example, the substrate precursor or the substrate can first be specifically cleaned with water and / or a solvent.

[0051] The substrate precursors can be processed in batches to form several substrates.

[0052] In addition, the substrate can be finely cleaned, for example, by plasma etching before being introduced into the reaction chamber.

[0053] After the antiwear layer has been deposited, the coated substrate can also be cooled and removed from the reaction chamber.

[0054] The object of the invention is also solved by a coated object comprising a substrate and an antiwear layer applied to the surface of the substrate, where the antiwear layer comprises a Ma2C phase, where Ma is a transition metal of group 5 or 6 of the periodic table, and where the content of Ma in the antiwear layer is at least 60 atomic % based on the total amount of transition metals in the antiwear layer.

[0055] Specifically, the coated object is obtained by the above method. The features and characteristics of the method according to the invention similarly apply to the coated object and vice versa, and reference is made to the above explanation.

[0056] The substrate of the coated object is specifically hard metal, cermet or tool steel. Hard metals include, for example, metal carbides, where the metal is selected from the group consisting of tungsten, titanium, tantalum, niobium and mixtures thereof, and a binder, for example a cobalt-based binder.

[0057] The coated object is specifically a cutting tool, for example a cutting tool for chip removal machining.

[0058] The Ma2C phase is specifically a V2C-, Nb2C-, W2C- or Mo2C phase.

[0059] The wear-resistant layer may have a nanocrystalline structure comprising a main phase and a secondary phase, where the main phase is the Ma2C phase and the secondary phase is a cubic nitride or carbonitride phase containing a second transition metal Mb. The secondary phase may have a lower hardness than the Ma2C phase but higher toughness.

[0060] The second transition metal Mb is specifically the same as the transition metal previously described in connection with the method according to the invention and reference is made to the above.

[0061] In one variant, the wear-resistant layer is the only coating applied to the substrate.

[0062] In another variant, a top layer of MaC, MbN and / or MbCN is applied to the wear-resistant layer, where Ma represents the same transition metal as in the Ma2C phase and where Mb represents the same transition metal as in the secondary phase.

[0063] The coated object preferably does not contain alternating layers. In other words, preferably no alternating layers are applied to the substrate or the wear-resistant layer.

[0064] The thickness of the wear-resistant layer may be in the range of 1 to 10 μm, preferably 3 to 6 μm.

[0065] Specifically, the plastic hardness of the wear-resistant layer is at least 30 GPa, preferably at least 35 GPa, for example 35 GPa to 45 GPa. These types of wear-resistant layers have high resistance to mechanical loads, have a reduced intrinsic voltage and therefore very good layer adhesion on metal substrates. As described in the prior art, such a hardness-adhesion combination is not achievable in the case of coatings having conventional materials as their main component (for example titanium aluminum nitride (TiAlN) or titanium diboride (TiB2)).

[0066] The hardness of the plastic refers to the hardness determined by a force penetration tester and can be determined in accordance with ISO 14577-1.

[0067] Specifically, the intrinsic compressive voltage of the wear-resistant layer is 4.5 GPa or less, preferably 2.5 GPa or less, for example 2 GPa or less.

[0068] The intrinsic compressive voltage of the layer can be determined by measuring the deflection of a flexible coated sample of known thickness and known elastic modulus, wherein the intrinsic compressive voltage can be calculated according to the so-called Stoney equation.

[0069]

[0070] where σ represents the intrinsic compressive voltage, E s is the elastic modulus of the substrate, h s is the substrate thickness, h is the layer thickness, v s is the Poisson's ratio of the substrate and R is the radius of deflection.

[0071] X-ray diffraction can also be used to determine the intrinsic compressive voltage.

[0072] X-ray diffraction can also be used for further characterization of the wear-resistant layer. By exciting the sample with Cu Kα radiation and changing the beam angle in the range of 20 to 90 degrees, conclusions can be drawn about the presence of crystalline phases, lattice planes and the diameter of coherent scattering regions.

[0073] The analysis can be completed by fitting the measured diffraction reflections with a Gaussian function to determine the area, half-width, position of the peak maximum and other characteristics of the reflection.

[0074] The half-width of the peak allows the use of the well-known Scherrer formula to determine the size of the microcrystals or the extent of the coherent scattering region. Description of the Drawings

[0075] Additional features and characteristics result from the following description of exemplary embodiments and from the drawings, which exemplary embodiments should not be understood in a limiting sense. These drawings show:

[0076] - Figure 1 , which is a first embodiment of a coated object according to the invention,

[0077] - Figure 2 , which is a second embodiment of a coated object according to the invention,

[0078] - Figure 3 , which is for producing according to the invention Figure 1 and Figure 2Block diagram of a method for a coated object,

[0079] - Figure 4 , which is an X-ray diffraction pattern of an exemplary wear-resistant layer, and

[0080] - Figure 5 , which is an X-ray diffraction pattern of another exemplary wear-resistant layer. Detailed Description of the Invention

[0081] Figure 1 Shows a schematic representation of a first embodiment of a coated object 10 according to the present invention, the coated object being specifically a cutting tool, for example a cutting tool for chip removal machining.

[0082] The coated object 10 includes a substrate 12 and a wear-resistant layer 16 applied to a surface 14 corresponding to the upper side of the substrate 12.

[0083] The substrate 12 is made of hard metal, cermet or tool steel. Hard metals include, for example, metal carbides, where the metal is selected from the group consisting of tungsten, titanium, tantalum, niobium and mixtures thereof, and a binder, such as a cobalt-based binder.

[0084] The wear-resistant layer 16 has a nanocrystalline structure, which includes a main phase and a secondary phase. The main phase is the Ma2C phase, where Ma is an early transition metal, which is a transition metal of the fifth or sixth group of the periodic table.

[0085] The secondary phase is a cubic nitride phase or a carbonitride phase containing a second transition metal Mb, and the second transition metal is selected from the group consisting of transition metals vanadium and chromium of the fourth group of the periodic table and combinations thereof.

[0086] The Ma2C phase is specifically a V2C-, Nb2C-, W2C or Mo2C phase.

[0087] According to the present invention, the Ma2C phase is the main component of the wear-resistant layer 16. This means that based on the total amount of transition metals in the wear-resistant layer 16, the proportion of Ma contained in the main phase in the wear-resistant layer 16 is at least 60 atomic %.

[0088] Specifically, the molar fraction ratio of the metal Mb forming the nitride or carbonitride to the metal Ma forming the carbide is less than 1:1. For example, the molar fraction ratio x of Mb to Ma is in the range of 0.5 ≤ x < 1.

[0089] In the nanocrystalline structure of the wear-resistant layer, the size of the existing microcrystals is 10 nm or less. The size of the microcrystals in the main phase may be different from the size of the microcrystals in the secondary phase. For example, the size of the microcrystals of the nitride or carbonitride in the secondary phase is larger than the size of the Ma2C in the main phase.

[0090] The hardness of the anti-wear layer is at least 30 GPa, preferably at least 35 GPa, for example 35 GPa to 45 GPa, and its thickness can be in the range of 1 to 10 μm, preferably 3 to 6 μm.

[0091] As Figure 1 can be seen, the anti-wear layer 16 is the only layer applied to the substrate 12.

[0092] It is also possible to no longer use the secondary phase, but instead use a nanocrystalline structure having a primary phase and a secondary phase. For example, the anti-wear layer 16 can consist of the Ma2C phase.

[0093] Figure 2 Schematically shows a second embodiment of the coated object 10 according to the invention.

[0094] The second embodiment is essentially the same as the first embodiment, and therefore only the differences will be discussed below. The same reference numerals indicate the same or functionally identical components, and reference is made to the above.

[0095] In the second embodiment, an additional top layer 18 is applied to the anti-wear layer 16, wherein the anti-wear layer 16 is arranged between the substrate 12 and the top layer 18.

[0096] The top layer 18 is made of a metal carbide (MaC), where Ma represents the same transition metal as used in the Ma2C phase of the anti-wear layer 16.

[0097] The top layer 18 can also additionally or alternatively contain a nitride and / or a carbonitride of a second transition metal Mb, where Mb represents the transition metal of the secondary phase.

[0098] The top layer 18 is thinner than the anti-wear layer 16.

[0099] Figure 3 Shows a block diagram of a method for producing a coated object 10 according to the invention according to the invention.

[0100] First, a substrate precursor is provided and subjected to a cleaning step, wherein the cleaning step is specifically carried out with water and / or a solvent ( Figure 3 step S1 in).

[0101] Then the substrate precursor is charged to form a number of substrates 12 ( Figure 3 step S2 in).

[0102] Of course, it is also possible to directly provide and clean the substrate 12, so that the charging step can be omitted.

[0103] Then the substrate 12 is cleaned, for example, by plasma etching ( Figure 3 step S3 in), and thereafter the substrate is placed in a reaction chamber ( Figure 3Step S4) in

[0104] Then, an anti - wear layer 16 and optionally a top layer 18 are provided for the substrate by PVD Figure 3 in step S5) in

[0105] thereby forming the coated object 10. The anti - wear layer 16 and optionally the top layer 18 are applied to the substrate 12 by magnetron sputtering (i.e., by HIPIMS (High - Power Pulsed Magnetron Sputtering)).

[0106] Then, the coated object 10 is cooled and removed from the reaction chamber Figure 3 in step S6) in

[0107] Hereinafter, the method according to the invention and the properties of the coated object 10 obtained by the method according to the invention are further illustrated by way of example.

[0108] Example 1 (non-reactive process, pulsed substrate voltage)

[0109] A tungsten carbide cutting insert SNGA120408 (6 wt.% Co binder) and a steel bar (material C45, dimensions 60×10×0.2 mm) are used as substrates in a CC800 HIPIMS coating system from Cemecon. The reaction chamber is equipped with a segmented target, i.e., a target having an upper half made of tungsten and a lower half made of graphite. An anti - wear layer is provided for both substrates by HIPIMS - PVD, using the deposition conditions listed in Table 1. Then, the chemical composition of the coated object is characterized using a scanning electron microscope (also known as "EDX" for "Energy - Dispersive X - Ray Analysis"), and its mechanical properties are characterized using a force indentation tester according to ISO14577 - 1 and using a bending bar, and the intrinsic voltage (referred to as "ES") is evaluated using the Stone equation. In all cases, the layer thickness is approximately 2 μm.

[0110] Table 2 shows the element ratios of tungsten to carbon (each in atomic percentage) determined by EDX for the corresponding coatings and other characteristic values. The variation in the composition of the anti - wear layer is obtained by positioning the substrate vertically in the reaction chamber, such that the metal content decreases from the top (sample 1) to the bottom (sample 4).

[0111] The one marked as "V" is determined by sandblasting with corundum powder AWear removal of "". During this process, corundum powder was thrown onto the coated test specimens at a pressure of 4 bar for 60 seconds. On the surface that was polished before coating and partially covered during sandblasting, at least ten individual measurements of the layer thickness were then taken using XRF (X-ray fluorescence analysis). The average of these measurements was compared with the initial layer thickness, which was also determined based on at least ten individual XRF measurements in the non-irradiated area and set to a value of 100%.

[0112] As described above, the crystallite size was determined using Peak-Fit and the Scherrer formula.

[0113] Table 1: HIPIMS process deposition conditions (non-reactive process, only main phase).

[0114]

[0115] Table 2: Properties of the coated objects (pulsed substrate voltage, only main phase).

[0116]

[0117] As can be seen in Table 2, the plastic hardness and wear resistance achieved with the composition according to Sample 3 are optimal, while higher and lower tungsten contents both result in a decrease in plastic hardness and wear resistance.

[0118] Figure 4 X-ray diffraction patterns of Samples 1, 3, and 4 are shown. It can be seen that as the tungsten content decreases, the intensity of the (101) diffraction reflection of the β-W2C phase decreases and its width increases. Therefore, the W:C ratio according to Sample 3 results in an optimal W2C content in the anti-wear layer in terms of achievable plastic hardness and intrinsic compressive voltage.

[0119] By digitally adjusting the corresponding shape of the (101) diffraction reflection (so-called "fitting"), a reflection half-width of 1.6° was obtained. The crystallite size was determined to be approximately 5 nm using the Scherrer formula (neglecting the instrument-related broadening of the reflection).

[0120] The diffraction reflections identifiable in the X-ray diffraction pattern that can be assigned to WC originate from the substrate used in each case.

[0121] Example 2 (non-reactive process, constant substrate voltage)

[0122] Similar to Example 1, coated objects were produced, where a non-pulsed or constant substrate voltage of the same level was used instead of pulsed operation. Table 3 summarizes the properties of the obtained samples, similar to Table 2.

[0123] Table 3: Properties of the coated objects (constant substrate voltage).

[0124] Sample W:C Plastic hardness, in GPa Intrinsic voltage ES, in GPa <![CDATA[V A %]]> 5 91:9 27.1 0.7 -7 6 88:12 29.0 1.1 -6 7 79:21 32.6 1.4 -6 8 51:49 24.1 0.5 -15

[0125] The comparison of Samples 1 to 4 from Example 1 with the corresponding analogous Samples 5 to 8 from Example 2 clearly shows that the coated objects produced using HIPIMS have a higher hardness and a reduced intrinsic voltage, which results in a lower wear track depth than in the case of coated objects produced at a constant substrate voltage and otherwise identical process parameters.

[0126] Example 3 (reactive process, pulsed substrate voltage)

[0127] To study the influence of the nitride-based secondary phase, additional samples were prepared in a manner similar to Example 1 but according to the conditions in Table 4, where a segmented target was used in the reaction chamber, which contained tungsten as the first transition metal Ma (upper half) and titanium as the second transition metal Mb (lower half). Additionally, the reaction chamber was flushed with acetylene as a carbon-containing reactive gas to supply carbon and with nitrogen as a nitrogen-containing reactive gas to supply nitrogen.

[0128] Table 4: Deposition conditions for the HIPIMS process (reactive process, mixed phase).

[0129]

[0130] Table 5 summarizes the properties of samples obtained by HIPIMS similar to Tables 2 and 3 based on the ratio of the elemental ratio of tungsten to titanium (each in atomic percentage) determined by EDX.

[0131] Table 5: Properties of the coated objects (pulsed substrate voltage, mixed phase).

[0132]

[0133] Based on Samples 9 to 12, it is clear that the achievable hardness can be increased within a wide composition range by an additional nitride- or carbonitride-based secondary phase based on the second transition metal Mb without fear of a significant increase in the intrinsic voltage. At a plastic hardness of approximately 40 GPa (see Sample 11), no further wear could be detected under the selected sandblasting conditions.

[0134] Figure 5 X-ray diffraction patterns of Samples 9, 11, and 12 are shown. It can be seen that the TiN phase is dominant in all samples in the X-ray diffraction patterns, where the diffraction reflections of the (111) and (200) lattice planes show considerable intensity. The reflection of the (101) lattice plane of the W2C phase is only faintly visible. The crystallite size of the phase (calculated according to the Scherrer formula) is in the range of less than 10 nm.

[0135] List of reference numerals

[0136] 10 Coated object

[0137] 12 Substrate

[0138] 14 Surface

[0139] 16 Anti-wear layer

[0140] 18 Top layer

Claims

1. A method for producing a coated object (10), wherein the method comprises the following steps: - providing a substrate (12) in a reaction chamber, and - depositing an anti-wear layer (16) on the surface of the substrate (12) by physical vapor deposition, wherein a target is provided in the reaction chamber, the target containing at least a first transition metal Ma to produce a Ma2C phase in the anti-wear layer (16), the first transition metal being a transition metal from Group 5 or Group 6 of the periodic table, and wherein the proportion of Ma in the Ma2C phase in the anti-wear layer (16) is at least 60 atomic % relative to the total amount of transition metals in the anti-wear layer (16).

2. The method according to claim 1, wherein Ma is selected from the group consisting of: vanadium, niobium, tungsten, molybdenum and combinations thereof.

3. The method according to claim 1 or 2, wherein the anti-wear layer (16) is applied by magnetron sputtering.

4. The method according to claim 3, wherein the anti-wear layer (16) is applied by HIPIMS, wherein a power pulse is supplied to the target and a voltage pulse is supplied to the substrate, and wherein the supply of the power pulse and the voltage pulse has a time delay.

5. The method according to any one of claims 1 to 4, wherein a graphite cathode is further provided to supply carbon in the reaction chamber when depositing the anti-wear layer (16).

6. The method according to any one of claims 1 to 5, wherein for the supply of carbon, the reaction chamber is flushed with a carbon-containing reactive gas during the deposition of the anti-wear layer (16).

7. The method according to any one of claims 1 to 6, wherein the reaction chamber is heated to a temperature in the range of 100 °C to 600 °C.

8. The method according to any one of claims 1 to 7, wherein a pressure of 0.1 to 0.5 Pa is set in the reaction chamber.

9. The method according to any one of claims 1 to 8, wherein the target further contains a second transition metal Mb that forms a nitride to produce a nanocrystalline structure containing a main phase and a secondary phase when depositing the anti-wear layer (16), wherein the main phase is the Ma2C phase, and the secondary phase is a cubic nitride phase or a carbonitride phase containing the second transition metal Mb.

10. The method according to claim 9, wherein the second transition metal Mb is selected from the group consisting of: transition metals vanadium, chromium, iron of Group 4 of the periodic table and combinations thereof.

11. The method according to claim 9 or 10, wherein during the deposition of the anti-wear layer (16), the reaction chamber is flushed with a nitrogen-containing reactive gas to supply nitrogen.

12. The method according to any one of claims 1 to 11, wherein the anti-wear layer (16) is the only coating applied to the substrate (12).

13. The method according to any one of claims 1 to 11, wherein a top layer (18) of MaC, MbN, and / or MbCN is applied to the antiwear layer (16), where Ma and Mb respectively represent the first transition metal and the second transition metal of the target.

14. The method according to any one of claims 1 to 13, wherein the antiwear layer (16) is applied to a thickness in the range of 1 to 10 μm.

15. A coated object (10) comprising a substrate (12) and an antiwear coating (16), the antiwear coating being disposed on a surface (14) of the substrate (12), wherein the antiwear coating (16) comprises a Ma2C phase, where Ma is a transition metal of Group 5 or Group 6 of the periodic table, and wherein the proportion of Ma in the antiwear layer (16) is at least 50 atomic % based on the total amount of transition metals in the antiwear layer (16).

16. The coated object (10) according to claim 15, wherein the plastic hardness of the antiwear layer (16) is at least 30 GPa.

17. The coated object (10) according to claim 15 or 16, wherein the intrinsic compressive voltage of the antiwear layer (16) is 4.5 GPa or less.

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