Method for producing a coated article and coated article

Abstract

A method for producing a coated article (10), the method comprising the steps of: providing a substrate (12) in a reaction chamber, and depositing a wear protection layer (16) on a surface (14) of the substrate (12) by means of physical vapor deposition, wherein a target is provided in the reaction chamber which contains at least a first transition metal Ma which is a transition metal from the fifth or sixth group of the periodic table in order to produce a Ma2C phase in the wear protection layer, and wherein the proportion of Ma of the Ma2C phase in the wear protection layer (16) is at least 60 atomic percent, based on the total amount of transition metals in the wear protection layer (16). Furthermore, a coated article (10) is specified.

Description

The invention relates to a method for producing a coated article and a coated article.In order to increase the resistance of articles such as cutting and machining tools, it is known to apply coatings to the surface of the respective article, which coatings are distinguished in particular by a high hardness. For example, by means of physical vapor deposition (PVD), coatings of titanium aluminum nitride (TiAlN), tungsten carbide (WC) or titanium carbide (TiC) can be deposited. It is also known to apply amorphous carbon (also referred to as diamond-like carbon, DLC) as a coating of high hardness. However, coatings of this type are limited with regard to the achievable layer thickness and layer adhesion.Coatings of so-called "superhard" materials with a plastic hardness of more than 40 GPa are also known, for example of titanium diboride (TiB 2). However, coatings of superhard materials tend to be brittle, which, due to the tendency to chip, adversely affects the life of correspondingly coated articles.It is an object of the invention to provide a method with which a coating is produced which bonds a high hardness, low residual stress and good layer adhesion to one another, and to provide an article with such a coating.The object is achieved according to the invention by a method for producing a coated article, wherein the method comprises the following steps:providing a substrate in a reaction chamber; anddepositing a wear protection layer on a surface of the substrate by means of physical vapor deposition, wherein a target is placed in the reaction chamber, said target containing at least one first transition metal Ma, which is a transition metal from the fifth or sixth group of the periodic table, in order to produce a Ma 2 C phase in the wear protection layer, and wherein the proportion of Ma of the Ma 2 C phase in the wear protection layer is at least 60 atomic percent, based on the total amount of transition metals in the wear protection layer.The invention is based on the basic idea of applying a wear protection layer which has a metal carbide phase with a high metal content as the main component, namely a dimetal carbide phase (Ma 2 C phase). It has been found that such phases are distinguished by a particularly high hardness and can be produced in a targeted manner by PVD methods by using a target in the reaction chamber as cathode, which contains the respective transition metal Ma or consists thereof and can thus release the transition metal Ma via the respective PVD method.The use of metal monocarbide phases as main component in the wear protection layer, as are produced by equilibrium processes during sintering and / or chemical vapor deposition (CVD), for example TiC or WC, is dispensed with according to the invention. This does not of course exclude that corresponding phases can be present to a small extent in the wear protection layer.In this way, coated articles can be obtained which, owing to the process procedure according to the invention, bond together high hardness, low residual stress and excellent adhesion to metallic substrates.The substrate is in particular made of a hard metal, a cermet or a tool steel. The hard metal comprises, for example, a metal carbide, wherein 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.The coated object is in particular a cutting tool, for example a cutting tool for machining.The target contains, according to the present invention, a transition metal of the fifth or sixth group of the periodic table (referred to as "Ma"). Such transition metals are capable of forming the high hardness Ma 2 C phase provided in the present invention. This is not possible with other metals, for example titanium.For example, the target contains vanadium, niobium, tungsten or molybdenum. Accordingly, the Ma 2 C phase may be a V 2 C phase, Nb 2 C phase, W 2 C phase or Mo 2 C phase.Fundamentally, the type of PVD method is not further limited as long as the desired Ma 2 C phase can be generated in a targeted manner. For example, the wear protection layer is applied by magnetron sputtering or an arc method.The wear protection layer is applied in particular by means of magnetron sputtering. Magnetron sputtering enables rapid layer growth during the deposition of the wear protection layer with constant pressure within the reaction chamber.The argon flow through the reaction chamber during the deposition of the wear protection layer is in particular 200 to 600 ml n / min, preferably 300 to 500 ml n / min, wherein mL n / min here and in the following denotes the volume of the respective gas under normal conditions (273.15 K and 1013.25 hPa) per minute.The wear protection layer is preferably applied by means of HIPIMS (high power pulse magnetron sputtering), wherein the target is supplied with power pulses and the substrate is supplied with voltage pulses, and wherein the power pulses and the voltage pulses are supplied with a time delay. HIPIMS is distinguished by power densities and high ionization degrees of the material removed from the target which are further increased compared to other magnetron sputtering methods. By using power pulses, each of the pulses can have a higher maximum power than is possible in the case of a permanently applied electric field, since the discharge takes place in a short time interval. The target can cool between the respective power pulses.The power pulses accordingly serve to remove material from the target placed in the reaction chamber and to deliver it into the plasma present in the reaction chamber. The voltage pulses which are applied to a rotary table with the objects or substrates to be coated accelerate the ionized material from the plasma in the direction of the substrate, so that the material deposits on the substrate placed in front in the form of the wear protection layer.Accordingly, each power pulse on the target is assigned a voltage pulse on the substrate or on the substrate holder. The time offset between power pulse and voltage pulse relates accordingly to the respectively assigned power and voltage pulses. This is also referred to as a "synchronized pulse.".The time offset makes it possible to set the proportion of metal ions in the plasma in the reaction chamber in a targeted manner at the time at which the ions are accelerated from the plasma in the direction of the substrate, and thus to generate the desired composition in the deposited phase. This results in a particularly flexible method configuration. Reference is made by way of example to the method for coating a substrate by means of HIPIMS as described in EP 2 761 050 B1.The time offset is in particular a time offset of 30 to 100 μs, preferably of 40 to 80 μm. A shorter time offset may lead to increased incorporation of argon ions into the wear protection layer, which would increase its residual compressive stress, while a time offset of more than 100 μs may lead to a reduction in the amount of metal ions.Furthermore, by depositing the wear protection layer by means of HIPIMS, the proportion of argon incorporated into the growing layer is reduced and the proportion of the implanted metal ions is increased compared to other PVD methods. In this way, the residual stress of the wear protection layer is further reduced without the need to fear disadvantages with regard to the achievable plastic hardness.The target power, i.e. the cathode power in the HIPIMS process, is in particular 5 to 12 kW, preferably 6 to 10 kW.The bias voltage between target and substrate is in particular in the range from 50 to 250 V, preferably from 120 to 200 V.In order to supply the reaction chamber with the carbon necessary for the construction of the Ma 2 C phase, an additional graphite cathode can be placed in the reaction chamber during the deposition of the wear protection layer for supplying carbon.The operation of the graphite cathode is tuned with the target pulses that ablate material from the target, such that the desired transition metal-carbon ratio is achieved in the plasma, to in turn produce the desired composition of the phase to be deposited on the substrate. In other words, co-sputtering is carried out in this variant.The graphite cathode power is in particular 1 to 5 kW. Thus, the graphite cathode power is in particular smaller than the target power.In addition or as an alternative to the use of a graphite cathode, during the deposition of the wear protection layer for supplying carbon, a carbon-containing reactive gas, for example acetylene, can be flushed through the reaction chamber.For example, the flow of carbon-containing reactive gas through the reaction chamber during the deposition of the wear protection layer is 10 to 100 mL n / min, preferably 20 to 50 mL n / min.The carbon-containing reactive gas, for example acetylene, is split in the plasma present in the reaction chamber, the carbon ions necessary for producing the Ma 2 C phase being produced. In other words, in this variant, reactive sputtering is carried out.In order to further simplify the construction and operation of the reaction chamber, in particular either a graphite cathode is provided or the reaction chamber is flushed through during the deposition of the wear protection layer with the carbon-containing reactive gas.The reaction chamber is heated in particular to a temperature in the range from 100 to 600° C., preferably from 300 to 500° C. At temperatures below 100° C., too low a layer adhesion of the wear protection layer on the substrate may occur. A temperature above 600° C. leads to an increasingly excessive energy requirement and may result in precipitation of graphite in the wear protection layer, which would lead to a reduction in the hardness.In the reaction chamber, during the deposition of the wear protection layer, a pressure of in particular 0.1 to 0.5 Pa is set, preferably of 0.2 to 0.45 Pa. A pressure of less than 0.1 Pa may result in insufficient layer growth rates, while a pressure of more than 0.5 Pa may reduce the mean free path of the ions and thus the pulse injection into the growing layer too much.The target may further include a nitride-forming second transition metal Mb to produce a nanocrystalline structure comprising a primary phase and a secondary phase when depositing the anti-wear layer, wherein the primary phase is the Ma 2 C phase and the secondary phase is a cubic nitride or carbonitride phase including the second transition metal Mb.The target may contain the first transition metal Ma and the second transition metal Mb in the form of an alloy. For example, the target is made of an alloy of the first transition metal Ma and the second transition metal Mb.The secondary phase ensures a reduction in the crystallite sizes in the primary phase, i.e. the crystallites of the Ma 2 C phase, so that the microstructure of the wear protection layer is refined and intrinsic stresses caused by growth can be further reduced. A nanocrystalline structure is understood to mean that the respective crystallites of the structure have a size of 10 nm or less.In this way, a so-called nanocomposite structure is produced in the wear protection layer, in which coexistence of nitride and / or carbonitride phases with carbide phases occurs, for example, Ma 2 C / MbN or Ma 2 C / MbCN.The use of the secondary phase in the wear protection layer additionally increases its chemical resistance, which has an advantageous effect on the service life of the coated article, in particular when processing ferrous substrates.The second transition metal Mb is a strong nitriding agent. Preferably, the second transition metal Mb is selected from the group consisting of the transition metals of the fourth group of the periodic table (also referred to as "titanium group"), vanadium, chromium, and combinations thereof.In order to supply the nitrogen required for building up the secondary phase to the reaction chamber, the reaction chamber can be flushed with a nitrogen-containing reactive gas, for example with nitrogen, during the deposition of the wear protection layer for supplying nitrogen.The flow of nitrogen-containing reactive gas can be 10 to 100 ml n / min, preferably 20 to 50 ml n / min.Whether the Ma 2 C phase or the secondary phase is deposited at a given point in time in the deposition process, or a mixture of the two phases, can be adjusted via the target power, the graphite cathode power, the flow of carbon-containing reactive gas and / or the flow of nitrogen-containing reactive gas.In one variant, the anti-wear layer is the only coating applied to the substrate. In this way, a particularly simple coating process is realized, which already leads to excellent performance characteristics of the coated article on account of the properties of the Ma 2 C phase generated in a targeted manner, optionally in combination with the secondary phase.In another variant, a finishing layer of MaC, MbN and / or MbCN is applied on the wear protection layer, wherein Ma denotes the first transition metal Ma and Mb denotes the second transition metal Mb of the target. In other words, a termination layer of "conventional" transition metal monocarbide, transition metal nitride or of transition metal carbonitride can be applied. In this case, too, the desired composition of the terminating layer can be achieved by suitable selection of the process parameters, in particular by adapting the graphite cathode power, the flow of carbon-containing reactive gas and / or the flow of nitrogen-containing reactive gas.In a further variant, a terminating layer of pure carbon can be applied by turning off the target, i.e. the target of transition metals. This allows the tendency of the coated object to rub to be reduced once more.The coated article is preferably free of alternating layers. In other words, preferably no alternating layers are applied to the substrate or to the wear protection layer. Here, alternating layers are understood to mean a sequence of at least three layers in which at least two layers chemically different from one another repeat in a regular pattern starting from the substrate. Complicated deposition methods can thus be avoided, while the desired durability and hardness of the coating are still achieved by the use of the Ma 2 C phase in the wear protection layer.The wear protection layer can be applied in a thickness in the range from 1 to 10 μm, preferably from 3 to 6 μm. Corresponding layer thicknesses can be achieved quickly and with comparatively little material use. With such layer thicknesses, wear protection layers with a plastic hardness of at least 30 GPa can be obtained, preferably of at least 35 GPa, which at the same time have a high toughness and thus a low tendency to chip off.The method according to the invention can of course also comprise further method steps.For example, a substrate precursor or the substrate can first be purified, in particular aqueously and / or with a solvent.The substrate precursor can be characterized to form multiple substrates.In addition, fine cleaning of the substrate is possible before introduction into the reaction chamber, for example by means of plasma etching.After the deposition of the wear protection layer, the coated substrate can also be cooled and removed from the reaction chamber.The object of the invention is furthermore achieved by a coated article comprising a substrate and a wear protection layer applied to the surface of the substrate, wherein the wear protection layer has a Ma 2 C phase, wherein Ma is a transition metal of the fifth or sixth group of the periodic table, and wherein the proportion of Ma in the wear protection layer is at least 60 atomic percent, based on the total amount of transition metals in the wear protection layer.The coated article is obtained in particular by means of the method described above. The features and properties of the method according to the invention apply correspondingly analogously to the coated article and vice versa, and reference is made to the above explanations.The substrate of the coated object is in particular made of a hard metal, cermet or a tool steel. The hard metal comprises, for example, a metal carbide, wherein 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.The coated object is in particular a cutting tool, for example a cutting tool for machining.The Ma 2 C phase is in particular a V 2 C phase, Nb 2 C phase, W 2 C phase or Mo 2 C phase.The anti-wear layer may have a nanocrystalline structure comprising a primary phase and a secondary phase, wherein the primary phase is the Ma 2 C 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 Ma 2 C phase, but a higher toughness.The second transition metal Mb is in particular the same transition metal as described above in connection with the method according to the invention, and reference is made to the above explanations.In one variant, the anti-wear layer is the only coating applied to the substrate.In another variant, a finishing layer of MaC, MbN and / or MbCN is applied on the wear protection layer, wherein Ma denotes the same transition metal as in the Ma 2 C phase and wherein Mb denotes the same transition metal as in the secondary phase.The coated article is preferably free of alternating layers. In other words, preferably no alternating layers are applied to the substrate or to the wear protection layer.The wear protection layer can have a thickness in the range from 1 to 10 μm, preferably from 3 to 6 μm.The wear protection layer has in particular a plastic hardness of at least 30 GPa, preferably of at least 35 GPa, for example of 35 GPa to 45 GPa. Wear protection layers of this type offer high resistance to mechanical loads, with reduced residual stress and associated very good layer adhesion to metallic substrates. Such hardness-adhesion combinations are not achievable with coatings comprising conventional materials as the main component, for example titanium aluminum nitride (TiAlN) or titanium diboride (TiB 2) as described in the prior art.The plastic hardness denotes the hardness according to Force Penetration Tester and can be determined according to ISO 14577-1.The residual compressive stress of the wear protection layer is in particular 4.5 GPa or less, preferably 2.5 GPa or less, for example 2 GPa or less.The residual compressive stress of a layer can be determined by measuring the deflection of a flexible, coated sample of known thickness and modulus of elasticity, the residual compressive stress being calculated according to the so-called Stoney equation, in which σ denotes the residual compressive stress, E s the modulus of elasticity of the substrate, h s the substrate thickness, h the layer thickness, v s the Poisson's number of the substrate and R the radius of the deflection.It is also possible to determine the residual compressive stress by means of X-ray diffraction.X-ray diffraction can also be used for further characterization of the wear protection layer. Excitation with Cu Kα radiation and variation of the beam angle of incidence in the range from 20 to 90 degrees make it possible to derive statements about the presence of the crystalline phases, lattice planes and the diameters of coherently scattering regions.The evaluation can be carried out by adapting ("fit") the measured diffraction reflections by means of a Gaussian function in order to determine the area, full width at half maximum, position of the peak maximum and further characteristic variables of the reflection.The half-width of a peak permits determination of the crystallite size or the extent of the coherently scattering regions by means of the known Scherer formula.Further features and characteristics will become apparent from the following description of exemplary embodiments, which should not be understood in a limiting sense, and from the drawings. In these show:FIG. 1 shows a first embodiment of a coated article according to the invention,FIG. 2 shows a second embodiment of a coated article according to the invention,FIG. 3 shows a block diagram of a method according to the invention for producing the coated articles from FIGS. 1 and 2,FIG. 4 shows X-ray diffractograms of exemplary wear protection layers, and,FIG. 5 shows X-ray diffractograms of further exemplary wear protection layers.FIG. 1 shows a schematic representation of a first embodiment of the coated object 10 according to the invention, which is in particular a cutting tool, for example a cutting tool for machining.The coated article 10 includes a substrate 12 and a wear protection layer 16 applied to a surface 14 corresponding to a top surface of the substrate 12.The substrate 12 is made of a cemented carbide, a cermet or a tool steel. The hard metal comprises, for example, a metal carbide, wherein 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.The anti-wear layer 16 has a nanocrystalline structure comprising a primary phase and a secondary phase. The primary phase is a Ma 2 C phase, where Ma denotes a first transition metal that is a transition metal of the fifth or sixth group of the periodic table.The secondary phase is a cubic nitride or carbonitride phase containing a second transition metal Mb selected from the group consisting of the transition metals of the fourth group of the periodic table, vanadium, chromium and combinations thereof.The Ma 2 C phase is in particular a V 2 C phase, Nb 2 C phase, W 2 C phase or Mo 2 C phase.According to the invention, the Ma 2 C phase represents the main component of the wear protection layer 16. That is, the content of Ma contained in the primary phase in the anti-wear layer 16 is at least 60 atomic percent based on the total amount of transition metals in the anti-wear layer 16.In particular, the ratio of the molar fractions of the nitride- or carbonitride-forming metal Mb to the carbide-forming metal Ma is less than 1:1.In the nanocrystalline structure of the wear protection layer, the crystallites present have a size of 10 nm or less. The crystallite size in the primary phase may be different from the crystallite size in the secondary phase. For example, the second phase nitride or carbonitride has a larger crystallite size than the primary phase Ma 2 C.The wear protection layer has a hardness of at least 30 GPa, preferably of at least 35 GPa, for example of 35 GPa to 45 GPa, and can have a thickness in the range from 1 to 10 μm, preferably of 3 to 6 μm.As can be seen in FIG. 1, the anti-wear layer 16 is the only layer applied to the substrate 12.It is also possible that instead of the nanocrystalline structure with the primary phase and the secondary phase, the use of the secondary phase is dispensed with. For example, the wear protection layer 16 can consist of a Ma 2 C phase.Figure 2 schematically illustrates a second embodiment of the coated article 10 of the present invention.The second embodiment corresponds substantially to the first embodiment, so that only differences will be discussed below. Identical reference symbols identify identical or functionally identical components, and reference is made to the above explanations.In the second embodiment, an additional finishing layer 18 is applied to the wear protection layer 16, wherein the wear protection layer 16 is arranged between the substrate 12 and the finishing layer 18.The terminating layer 18 is made of a metal carbide (MaC), wherein Ma denotes the same transition metal that is also used in the Ma 2 C phase of the wear protection layer 16.It is also possible for the terminating layer 18 additionally or alternatively to contain a nitride and / or a carbonitride of the second transition metal Mb, wherein Mb denotes the transition metal of the secondary phase.The end layer 18 has in particular a smaller thickness than the wear protection layer 16.FIG. 3 shows a block diagram of a method according to the invention for producing the coated article 10 according to the invention.First, a substrate precursor is provided and subjected to cleaning, the cleaning being carried out in particular with water and / or a solvent (step S 1 in FIG. 3 ).Subsequently, the substrate precursor is characterized to form a plurality of substrates 12 (step S 2 in FIG. 3 ).Of course, it is also possible for the substrate 12 to be provided and cleaned directly, so that the charging step can be omitted.The substrate 12 is then fine cleaned, for example, by plasma etching (step S 3 in FIG. 3 ) after being placed in a reaction chamber (step S 4 in FIG. 3 ).The substrate is then provided with the wear protection layer 16, and optionally with the finishing layer 18, by means of PVD (step S 5 in FIG. 3 ) to form the coated object 10.The wear protection layer 16, and optionally the terminating layer 18, are applied to the substrate 12 in particular by means of magnetron sputtering, namely by means of HIPIMS (high power pulse magnetron sputtering).Subsequently, the coated article 10 is cooled and taken out of the reaction chamber (step S 6 in FIG. 3 ).The process according to the invention and the properties of the coated article 10 obtained by means of the process according to the invention are illustrated in more detail below with reference to examples.Example 1 (Non-reactive process, pulsed substrate voltage)As substrates, cemented carbide cutting inserts SNGA120408 (6 wt.% co-binder) and sections of steel strip (material C45, dimension 60 x10 x 0.2 mm) were placed in a coating plant CC800 HIPIMS from the manufacturer Cmecon. The reaction chamber was coated with a segmented target, i.e., a target having an upper half of tungsten and a lower half of graphite. Both substrates were provided with a wear protection layer by means of HIPIMS-PVD, using the deposition conditions listed in Table 1. The coated articles were subsequently characterized with regard to their chemical composition by means of scanning electron microscopy (also referred to as "EDX" for energy dispersive x-ray analysis) and with regard to their mechanical properties by means of a force penetration tester according to ISO 14577-1 and by means of bending strips and evaluation of the residual stress (referred to as "ES") by means of the Stoney equation. The layer thickness in all cases was about 2 μm.Table 2 gives the element proportions of tungsten to carbon determined by means of EDX (in atomic percent in each case) and further characteristic values of the respective coatings. The variation in the composition of the wear protection layer is obtained by vertically positioning the substrates within the reaction chamber, resulting in a metal content decreasing from top (sample 1) to bottom (sample 4).The wear removal, designated "V A", was determined by means of abrasive blasting with corundum powder. Corundum powders are spun onto the coated test specimens at a pressure of 4 bar for 60 seconds. On a surface polished before the coating and partially covered during the blasting, at least ten individual measurements of the layer thickness are subsequently carried out by means of XRF (for "x-ray fluorescence" analysis). The mean value of these measurements is compared with the starting layer thickness, which was likewise determined from at least ten individual XRF measurements in the non-irradiated region and is set to a value of 100%.Crystallite size was determined by peak fit and Schererer formula as described above. Table 1: Deposition conditions HIPIMS process (non-reactive process, primary phase only). Table 1: Deposition conditions HIPIMS process (non-reactive process, primary phase only).Pulse frequency in Hz2000Pulse duration in μs50Time offset between power and voltage pulses (cathode and stage pulses) in μs50Target power in kW6Substrate voltage in V150Pressure in Pa0,45Flow of argon in ml n / min500Table 2: Properties of the coated articles (pulsed substrate voltage, primary phase only).Table 2: Properties of the coated articles (pulsed substrate voltage, primary phase only).190:1031,21,5-8287:1332,41,8-5379:2134,31,1-3450:5025,80,5-17As is clear from Table 2, the plastic hardness and abrasion resistance obtainable in the composition according to Sample 3 is optimum, while both a higher and a lower tungsten content results in a reduction in the plastic hardness and the wear resistance.FIG. 4 shows X-ray diffractograms of samples 1, 3 and 4. it can be seen that, with a decreasing content of tungsten, the intensity of the (101) diffraction reflection of the β-W 2 C phase decreases and the width thereof increases. Accordingly, at a W:C ratio according to sample 3, a content of W 2 C in the wear protection layer is established, which enables an optimum with regard to achievable plastic hardness and residual compressive stress.By numerical matching of the respective shape of the (101) diffraction reflection (so-called "fit"), a reflection half width of 1.6° is obtained. The crystallite size is determined to be about 5 nm via the Scherer formula (neglecting instrument-related reflection broadening).The diffraction reflections which are to be identified in the X-ray diffractograms and are to be assigned to WC originate from the substrates used in each case.Example 2 (Non-reactive process, constant substrate voltage)Analogously to Example 1, coated articles were produced, in the production process of which, instead of pulsed operation, a non-pulsed or constant substrate voltage of the same level was used. Table 3 summarizes the properties of the samples obtained, analogous to Table 2.Table 3: Properties of the coated articles (constant substrate tension). Table 3: Properties of the coated articles (constant substrate tension).591:927,10,7-7688:1229,01,1-6779:2132,61,4-6851:4924,10,5-15It is clear from the comparison of samples 1 to 4 from example 1 with the respective analogous samples 5 to 8 from example 2 that coated articles produced by means of HIPIMS have a higher hardness with reduced residual stress, which result in a lower wear track depth than is the case with coated articles produced with otherwise the same process parameters with constant substrate stress.Example 3 (Reactive Process, Pulsed Substrate Voltage)To examine the influence of a nitride-based secondary phase, additional samples were prepared analogously to Example 1, but according to the conditions of Table 4, using in the reaction chamber a segmented target containing tungsten as the first transition metal Ma (upper half) and titanium as the second transition metal Mb (lower half). In addition, the reaction chamber was flushed with acetylene as the carbon-containing reactive gas for supplying carbon and with nitrogen as the nitrogen-containing reactive gas for supplying nitrogen. Table 4: Deposition conditions HIPIMS process (reactive process, mixed phase). Table 4: Deposition conditions HIPIMS process (reactive process, mixed phase).Pulse frequency in Hz1000Pulse duration in μs100Time Offset between Power and Time Offset50Voltage pulse (cathode and stage pulse) in μsTarget power in kW6Substrate voltage in V (HIPIMS)180Pressure in Pa0,45Flow of argon in ml n / min500Flow of acetylene in ml n / min20Flow of nitrogen in ml n / min30Table 5 summarizes the properties of the HIPIMS samples, analogous to Tables 2 and 3, focusing on the ratio of tungsten to titanium element fractions determined by EDX (in atomic percent each). Table 5: Properties of the coated articles (pulsed substrate voltage, mixed phase). Table 5: Properties of the coated articles (pulsed substrate voltage, mixed phase).993:735,41-71089:1136,71,5-31185:1539,42,501273:2733,61,5-5It is clear from samples 9 to 12 that the achievable hardness can be increased over a wide composition range by the additional nitride- or carbonitride-containing secondary phase based on the second transition metal Mb without having to fear a substantial increase in the residual stress. In the case of plastic hardening of about 40 GPa (cf. sample 11), wear removal can no longer be detected under the selected blasting conditions.FIG. 5 shows X-ray diffractograms of samples 9, 11 and 12, it being evident that the TiN phase is dominant in all samples in the X-ray diffractogram, the diffraction reflections of the (111) and (200) grating planes having a comparable intensity. The reflection of the (101) grating plane of the W 2 C phase can only be seen weakly. The crystallite sizes of the phases (calculated according to the Scherer formula) are in the range of less than 10 nm.List of reference characters10 Coated article 12 Substrate 14 Surface 16 Wear protection layer 18 Finishing layerReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedEP 2 761 050 B1

[0019]

Claims

A method for producing a coated article (10), the method comprising the steps of: - providing a substrate (12) in a reaction chamber, and - depositing a wear protection layer (16) on a surface of the substrate (12) by means of physical vapor deposition, wherein a target containing at least one first transition metal Ma, which is a transition metal from the fifth or sixth group of the periodic table, is placed in the reaction chamber to produce a Ma 2 C phase in the wear protection layer (16), and wherein the proportion of Ma of the Ma 2 C phase in the wear protection layer (16) is at least 60 atomic percent, based on the total amount of transition metals in the wear protection layer (16).The method of claim 1, wherein Ma is selected from the group consisting of vanadium, niobium, tungsten, molybdenum, and combinations thereof.Method according to claim 1 or 2, wherein the wear protection layer (16) is applied by means of magnetron sputtering.Method according to claim 3, wherein the wear protection layer (16) is applied by means of HIPIMS, wherein the target is supplied with power pulses and the substrate is supplied with voltage pulses, and wherein the power pulses and the voltage pulses are supplied with a time delay.Method according to one of Claims 1 to 4, wherein, during the deposition of the wear protection layer (16), a graphite cathode is additionally provided in the reaction chamber for supplying carbon.Method according to one of Claims 1 to 5, wherein during the deposition of the wear protection layer (16) for supplying carbon, a carbon-containing reactive gas is flushed through the reaction chamber.The method of any one of claims 1 to 6, wherein the reaction chamber is heated to a temperature in the range of 100 to 600°C.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.The method of any one of claims 1 to 8, wherein the target further contains a nitride-forming second transition metal Mb to produce a nanocrystalline structure comprising a primary phase and a secondary phase during deposition of the anti-wear layer (16), wherein the primary phase is the Ma 2 C phase and the secondary phase is a cubic nitride or carbonitride phase containing the second transition metal Mb.The method of claim 9, wherein the second transition metal Mb is selected from the group consisting of the transition metals of the fourth group of the periodic table, vanadium, chromium, iron, and combinations thereof.Method according to claim 9 or 10, wherein during the deposition of the wear protection layer (16) for supplying nitrogen, the reaction chamber is flushed with a nitrogen-containing reactive gas.The method of any one of claims 1 to 11, wherein the anti-wear layer (16) is the only coating applied to the substrate (12).Method according to one of Claims 1 to 11, wherein a terminating layer (18) made of MaC, MbN and / or MbCN is applied on the wear protection layer (16), wherein Ma and Mb denote the first transition metal and the second transition metal of the target, respectively.Method according to one of claims 1 to 13, wherein the wear protection layer (16) is applied in a thickness in the range of 1 to 10 μm.A coated article (10) comprising a substrate (12) and a wear protection layer (16) applied to a surface (14) of the substrate (12), wherein the wear protection layer (16) has a Ma 2 C phase, wherein Ma is a transition metal of the fifth or sixth group of the periodic table, and wherein the proportion of Ma in the wear protection layer (16) is at least 50 atomic percent based on the total amount of transition metals in the wear protection layer (16).The coated article (10) of claim 15, wherein the anti-wear layer (16) has a plastic hardness of at least 30 GPa.The coated article (10) according to claim 15 or 16, wherein the compressive residual stress of the anti-wear layer (16) is 4.5 GPa or less.

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