Aicrsin-based coating for improved performance in a broad range of tool applications

Abstract

The present invention relates to a coated substrate, preferably a coated tool having excellent performances in a broad range of applications, in particular in cutting and / or forming applications. The coated substrate being coated with a coating system comprising an AlCrN bottom layer and an AlCrSiN upper layer.

Description

[0001]AlCrSiN-based coating for improved performance in a broad range of tool applications The present invention relates to hard coatings for tools granting improved performances in a broad range of applications (in particular for cutting and forming applications). Furthermore, the present invention relates to a method for producing the inventive coatings and corresponding coated substrates, in particular coated tools. Thus, the present invention relates also to coated substrates, preferably coated tools having excellent performance in a broad range of applications, in particular in cutting and forming applications. The inventive coated substrate being coated with a coating system comprising an AlCrN bottom layer and an AlCrSiN upper layer designed in such a manner that the coating architecture and properties allow using it for improving performance of tools in a big variety of applications. Prior art A diversity of AlCrN coatings is known from the prior art. Such coatings are generally produced having a strong columnar morphology. Well known methods for producing such kind of coatings are methods involving evaporation or sputtering of targets made of aluminum and chromium (AlCr-targets) by using physical deposition techniques (PVD techniques) and nitrogen gas as reactive gas for accomplishing a reactive PVD production of such AlCrN coatings. See for example the proposal of Derflinger et al. in EP1627094. Furthermore, several other AlCrN-based coatings available in the market consist of alloyed AlCrN (i.e. AlCrN comprising additional elements such as titanium (Ti), silicon (Si), boron (B), oxygen (O), carbon (C), and / or others). Such additional elements, also called dopant elements are used to modify the characteristics (i.e. properties) of AlCrN coatings to achieve better performance in different kind of applications, for example in cutting and forming applications. Likewise in different publications different designs of AlCrN-based coatings have been proposed. Ebersold et al. propose for example in WO2022129094 and WO2022129644 different methods for producing AlCrN-based coatings with increased wear resistance. As well Lechthaler et al. in EP2839051 and Eriksson et al. in EP3134561 propose concrete AlCrBN-based coating designs to achieve better performance in gear cutting applications. AlCrN-based coatings of the type AlCrSiN coatings are also known from the prior art. A non-patent literature publication in this regard is for example the scientific article titled “Effect of Plasma Nitriding Pretreatment on the Mechanical Properties of AlCrSiN- Coated Tool Steels”, published in the journal: Materials 2019, 12, 795 (www.mdpi.com / journal / materials). In this article Chang et al. describe a possible surface solution for warm stamping of stainless steels and light alloys. They propose concretely to combine two different processes for improving the performance of tool steel substrates and they test the proposed solution in an impact fatigue test conducted at room temperature and at high temperature. They do not report any results of any tests of the proposed solution in any real tool applications. They concretely propose to perform a plasma nitriding process before applying an AlCrSiN hard coating (see abstract and introduction). The coating is deposited by using PVD techniques of the type cathodic-arc evaporation using different targets as coating source material, operated in a reactive atmosphere comprising nitrogen and argon at a working pressure of 3 Pa, a deposition temperature of 250 °C, a target current of 70 A, and a negative bias voltage of -120 V (see materials and methods). The coating is suggested to be deposited in such a manner that it is formed of four layers: a first layer as interlayer made of CrN deposited directly on the nitrided substrate surface, followed directly by a second layer made of AlCrN nanolayers and CrN nanolayers deposited alternate one on each other, followed directly by a third layer made of AlCrSiN nanolayers and AlCrN nanolayers deposited alternate one on each other, followed directly by a fourth layer as top layer made of AlCrSiN, wherein the first layer deposited by arc-evaporation of a Cr-target for forming the CrN layer, the second layer deposited by arc evaporation of an Al0.7Cr0.3-target for the deposition of the AlCrN nanolayers and of the Cr target for the deposition of the CrN nanolayers, the third layer deposited by arc evaporation of an Al0.6Cr0.3Si0.1-target for the deposition of the AlCrSiN nanolayers and of the Al0.7Cr0.3-target for the deposition of the AlCrN nanolayers, and the fourth layer deposited by arc evaporation of the Al0.6Cr0.3Si0.1-target for the deposition of the AlCrSiN layer as top layer. Where the first and second layers exhibiting columnar morphology and having thickness (sum of thicknesses of the first and second layer) of about 0.82 µm, and the third and fourth layers exhibiting a much dense morphology and having thickness (sum of thicknesses of the third and fourth layer) of about 1.42 µm (see results and discussion). At least some very big disadvantages of this coating are the need of using two different processes as well as the need of using three different target compositions, which makes the process highly complex. Furthermore, the high use of CrN and in general high Cr content in the coating in comparison with the Al content and the use of a top layer with a non-stable crystalline phase result in a coating that cannot be successfully used in a variety of applications, for example is not appropriate for managing thermal loads in exigent milling operations. The use of a high value of negative bias voltage, in this case a constant value of -120 V for the deposition of the complete PVD coating makes the coating not appropriate for managing of micro- fissures. Chang et al. cited in the above-mentioned article a further non-patent literature publication related to AlCrSiN coatings, which is the scientific article titled “Interfacial structure, mechanical properties and thermal stability of CrAlSiN / CrAlN multilayer coatings”, published in the journal Materials Characterization 125 (2017) 1-6 (www.elsevier.com / locate / matchar). In this publication He et al. describe an analysis of the production of a multilayer film comprising alternated individual layers of AlCrN and of AlCrSiN, wherein the AlCrSiN layers exhibiting cubic crystalline phase in spite of containing a considerably high amount of Si, which should conduct to the formation of wurtzite crystalline phase instead of solely cubic crystalline phase, this effect being attained by using the AlCrN individual layers having cubic crystalline phase as a kind of template for the grow of AlCrSiN individual layers exhibiting cubic crystalline phase irrespective of the high Si content (see abstract and introduction). This multilayer film is a coating deposited by using PVD techniques of the type cathodic-arc evaporation using different targets as coating source material, concretely a target of AlCr having chemical element composition Al0.7Cr0.3, and a target of AlCrSi having chemical element composition Al0.6Cr0.3Si0.1, also using nitrogen as reactive gas at a working pressure of about 3 Pa, a deposition temperature of 550 °C, and a negative bias voltage of -100 V (see experimental). Multilayer films were produced having different modulations in relation to thickness of the AlCrN individual layers and thickness of the AlCrSiN individual layers. The thickness of the individual layers was maintained in nanometer size; therefore, the individual layers can be also called individual nanolayers of AlCrN and of AlCrSiN. The coating was in each case directly deposited on the substrate surface without indicating nor suggesting the use of a previous nitriding process for nitriding the substrate surface to be coated and also not indicating not suggesting the use of any interlayer between the substrate surface to be coated and the multilayer film. The chemical composition of the three multilayer films analyzed was respectively: Al0.67Cr0.32Si0.01N, Al0.62Cr0.33Si0.05N, Al0.54Cr0.37Si0.09N (see experimental, and results and discussion). At least some very big disadvantages of this coating are that this coating was not designed to work in any real application but was only deposited for making some analysis of the properties of the material created. Therefore, it is not appropriate for real applications and less for a big variety of cutting and / or forming applications. Furthermore, similarly like in the coating of Chang et al. mentioned above the Cr content in the coating in relation to the Al content is not appropriate for real applications involving exigent stress collective at high temperatures. The use of a high value of negative bias voltage, in this case a constant value of -100 V for the deposition of the complete PVD coating makes the coating not appropriate for managing of micro-fissures. AlCrSiN coatings are also described in the Chinese patent application having publication number CN 109161841 A. In this document Wang et al. describe a method for preparing an AlCrN / AlCrSiN nanocomposite multilayer coating that should be suitable for cutting difficult-to-process materials under harsh conditions, wherein the method is accomplished by using pulse arc ion plating technology. The substrate coated with this AlCrN / AlCrSiN superhard nanocomposite multilayer coating, comprising from bottom to top, a substrate, an AlCrN transition layer and an AlCrN / AlCrSiN nanocomposite multilayer functional layer formed by depositing alternated AlCrN individual nanolayers and AlCrSiN individual nanolayers. Wang et al, indicate that the AlCrN / AlCrSiN nanocomposite multilayer coatings exhibit single- phase cubic and a mixture of cubic wurtzite structures and infer that the diffraction peak of Si3N4indicates also the presence of an amorphous structure, and that the AlCrSiN nanocomposite structure is composed of amorphous Si3N4 wrapped in nanocrystalline (Al,Cr)N. At least some very big disadvantages of this coating is the method used for producing the coating, which is not ideal for attaining high productivity because of the very low deposition rate caused by the pulse pauses. The use of a high value of negative bias voltage, in this case a value in a range from -80 V to -180V for the deposition of the complete PVD coating makes the coating not appropriate for managing of micro-fissures. Furthermore, the use of solely a very thin AlCrN transition layer between the substrate and the functional AlCrSiN-containing multilayer results in a deficient mechanical support of the functional AlCrSiN-containing multilayer on the substrate for many applications. Furthermore, the high Cr content in the functional AlCrSiN-containing multilayer in relation to the Al content is not appropriate for managing thermal loads in exigent milling operations involving exigent stress collective at high temperatures. Disadvantages of the prior art The above-mentioned coating designs and methods have however the disadvantage that they allow producing coatings that are only well-suited for attaining good performance in only one kind or few kinds of applications (it means for example for attaining good performance in only one kind of cutting operation, e.g. in gear cutting applications). Therefore, such known coating solutions cannot be used as a broad- band coating that can be capable of performing well in many different applications. Furthermore, in spite of some of the known coatings mentioned above can be used in more than one kind of applications, they have still many limitations that prevent using them as a broad-band coating well-suitable for many different applications. For example, AlCrN coatings exhibits normally a strongly marked columnar growth, which is not optimal to stay properly on a sharp cutting edge of a cutting tool. In addition, because the morphology is homogeneous, the only interfaces being the ones formed between the columns of the coating, cracks can propagate easily from the top surface to the interface with the substrate and cause serious damage to the coating such as chipping. Moreover, despite known AlCrN coatings as well as known alloyed AlCrN coatings have demonstrated to be good coating systems with balanced properties. Likewise, the known AlCrSiN-based coatings are not good enough for improving performance of tools in a big plurality of applications including cutting and forming applications at least for the reasons explained above. Furthermore, the known methods described for the AlCrSiN-based coatings do not allow efficient production of stable and robust AlCrSiN-based coatings that provide the necessary mechanical, chemical and thermal stability to cutting and forming tools used in applications with very high stress collective at both low and high temperatures during a long lifetime. Therefore, for meeting the current and future increased demands the known coatings should still be improved notably regarding mechanical properties (e.g. indentation hardness and indentation modulus) as well as oxidation resistance at high temperatures. The above-mentioned “room for improvement” is crucial to reach better performance of tools in a big variety of more demanding applications, for example in many current and future more demanding cutting and forming operations. Objective of the present invention The main objective of the present invention is to provide a coating solution that allows overcoming the disadvantages of the prior art and further improving performance of tools used in a variety of applications, in particular in cutting and / or forming operations. Description of the present invention The objective of the present invention was attained by providing a coating system according to claims 1 to 11, and a method for producing a such inventive coating system according to claims 12 to 15. Figures 1 to 6 as well as some examples (comparative and inventive examples) and particularly preferred embodiments are used and described below for explanatory purposes. Therefore, they should not be understood as a limitation of the present invention. A coating system according to the present invention combines several features giving a clear advantage in a large diversity of cutting and forming operations when applied on a tool. Thus, the technical challenge to provide a coating that exhibits increased performance in comparison to already existing coatings that were already at a very good level was overcome. Thus, the present invention relates to a coating system comprising a lower layer 40 (also called bottom layer 40) of Al, Cr and N, and an upper layer 60 of Al, Cr, Si and N, as schematically shown in Figure 1 and Figure 2. According to a preferred embodiment of the present invention, the upper layer 60 comprises a transition region 61 (also called transition layer 61) and a top region 62 (also called top layer 62), as schematically shown in Figure 2. Thus, according to this preferred embodiment the coating system comprises a bottom layer 40, a transition layer 61, and a top layer 62. To limit the complexity of the coating and of its production, the coating was designed without using any adhesion layer deposited between the substrate surface 11 and the bottom layer 40. The bottom layer 40 consists preferably of aluminum chromium nitride, deposited by arcing AlCr-targets (at least one AlCr-target) in a nitrogen-containing reactive atmosphere, while the upper layer 60, respectively the transition layer 61 and top layer 62 consists preferably of aluminum chromium silicon nitride, deposited by co-arcing of AlCr- and AlCrSi-targets in a nitrogen-containing reactive atmosphere (at least one AlCr-target and at least one AlCrSi-target), therefore having a nanolaminated architecture formed of alternate deposited individual AlCrN nanolayers (from the AlCr- targets) and individual AlCrSiN nanolayers (from the AlCrSi-targets). Adding Si in the AlCrN system through co-arcing for forming the AlCrSiN upper layer 60, had several positive impacts, that resulted in at least following big advantages: - Refining the morphology of the coating from columnar to fine grains. - Introducing a clear sub-structuration with nano-layering of AlCrN layers and AlCrSiN layers, as the tool or substrate sees an alternation of different target materials because of its rotation in the coating chamber (the substrate surface to be coated faces periodically and consecutively each type of target, i.e. the at least one AlCr-target and the at least one AlCrSi-target, one after another). - Maintaining or increasing the indentation hardness (hardness HIT measured by nanoindentation techniques by using a Fischerscope). - Decreasing the indentation modulus (Young’s modulus EIT measured by nanoindentation techniques by using a Fischerscope). - Increasing the high-temperature oxidation resistance. The above-mentioned features make the inventive coating systems, and respectively the coated substrates coated with the inventive coating system, outstanding advantageously. Firstly, since the coating system is provided having a combination of morphologies, comprising a columnar bottom layer 40 and a fine-grained upper layer 60, the fine- grained layer offers the advantage to stay better at the cutting edge of a cutting tool, while the columnar bottom layer gives a strong base for the coating to grow. However, it is also essential that the columnar bottom layer 40 be a non-Si-containing layer and the fine-grained upper layer 60 be a Si-containing layer for attaining not only the advantageous mixed morphology but also the advantageous crystalline phase orientations, allowing the beneficial properties for a broad range of different applications. When using an upper layer 60, comprising a Si-containing transition layer 61 and a Si- containing fine-grained top layer 62, it results in the advantage that the transition layer 61 in-between of the columnar non-Si-containing bottom layer 40 and the Si-containing fine-grained upper layer 62, is used to accommodate this morphology change. Furthermore, the inventive coating allows the advantage of being a broad-band coating. It is like that because combining these two distinct morphologies a very good compromise is attained, which allows that the columnar morphology helps in applications where columnar morphology is better suited and the fine-grained morphology helps in applications where fine-grained morphology is better suited. Secondly, the fine-grained layer has a substructure in nanolayers that results from co- arcing of different target materials (AlCr and AlCrSi as already mentioned above). The combination of the above-mentioned nanolayering of the upper layer 60 (thus, respectively of the transition layer 61 and top layer 62) and the “columnar to fine- grained morphology” (from the columnar non-Si-containing bottom layer 40 to the fine- grained, nanolayered, Si-containing upper layer 60) of the coating system result in additional interfaces and thermal stability that are useful for preventing crack propagation within the coating. These cracks can simply come directly from mechanical stresses generated during the application of the coated substrate, for example due to the application of the coated tools in cutting or forming operations. Otherwise, thermal cracking can also appear, as a result of a big amount of thermal stresses. It can be for example the case in an interrupted cutting operation that is ran in wet conditions, which can cause strong thermal stresses to the coated tool being used. The architecture and properties of the coating systems and respectively coated substrates according to the present invention enable resisting such strong thermal stresses and preventing crack propagation at the same time. Thus, the inventive coating systems exhibit a relatively high level of compressive stresses, combined with the multiplication of internal interfaces. Thirdly, as a consequence of increasing or maintaining hardness HIT (in the context of the present description abbreviated as H) and reducing Young’s modulus EIT (in the context of the present description abbreviated as E), the H / E ratio is increased. Hence, since increasing the H / E ratio is widely recognized as a criterion to attain a better resistance to crack propagation as well as a better wear resistance, it is another advantage provided by the present invention. The inventors observed that the incorporation of Si in AlCrN, in a manner that results in a reduction of the Cr-content, i.e. by increasing Si and reducing Cr at the same time, has an additional effect on the crystal structure. This means for example if the Al- content is maintained constant and only the Cr-content is decreased and the Si-content is increased. In particular, the inventors observed that gradually adding Si into AlCrN to produce AlCrSiN with increased content of Si and reduced content of Cr can lead to a reduction in the crystallinity of the AlCrSiN, in such an extent that an entirely amorphous AlCrSiN layer can be produced. Surprisingly, best results were obtaining by adding Si into AlCrN for producing AlCrSiN (resulting in a AlCrSiN layer formed by co-arc-evaporation of AlCr- and AlCrSi-targets in a reactive, nitrogen-containing atmosphere, in this manner the AlCrSiN layer exhibiting a nanolayered or nanolaminated multilayer architecture formed of alternate deposited AlCrN individual nanolayers and AlCrSiN individual nanolayers), in such a manner that the Si concentration in the AlCrSiN layer was maintained in a range from 1 at.% up to 10 at.%, more preferably in a range from about 1 at.% up to about 6 at.%, still more preferably from about 2 at.% up to about 5 at.% (where these concentrations in atomic percentage correspond to the Si-content, when solely the elements Al, Cr and Si are being considered for the calculation). In the above-mentioned ranges, it was possible to attain the above-mentioned advantages and avoid an undesirable reduction of the crystallinity of the AlCrSiN layers being produced. The Al content in both the AlCr- as well as in the AlCrSi-targets was preferably always 70 at.%. Thus the Cr-content in the AlCr-target was 30 at.% and in the AlCrSi-targets was lower than 30 at.%, in each case depending respectively of the Si-content in the corresponding AlCrSi-target. In this manner it was possible to keep a well-defined face centered cubic structure (fcc structure) in the whole inventive coating system. This phenomenon might also be accentuated by the fact that the Al / Cr ratio is also increasing along the thickness of the inventive coating system from the bottom layer 40 deposited by using only AlCr-targets and the upper layer 60 deposited by using both AlCr- and AlCrSi-targets. For example, in one of the deposited inventive coating systems, the Al / Cr ratio was increased from approximately 2.1 at the bottom layer 40 to 2.6 at the upper layer 60 (or transition layer 61 and top layer 62). Thus, only a very low loss of crystallinity is produced, which is not detrimental at all, because the whole coating structure is still maintained in the fcc domain. In other words, all XRD peaks (with main focus on peaks 111 and 200) observed in the XRD diffractogram of the AlCrN layer (or XRD diffractogram of the coating comprising only AlCrN) are observed in the XRD diffractogram of the AlCrSiN layer (or diffractogram of the coating comprising both at least one AlCrN layer and at least one AlCrSiN layer). These peaks are well defined. However, in the XRD diffractogram of the AlCrSiN layer (or coating comprising AlCrSiN apart from AlCrN) the relative intensity of the peaks is smaller, and the peak width is larger than in the XRD diffractogram of the AlCrN layer (or coating only comprising AlCrN). Hence, globally speaking, the XRD-peaks corresponding to AlCrSiN (or coating comprising AlCrSiN apart from AlCrN) are shorter concerning height and are wider concerning width in comparison to them corresponding to the AlCrN layer (or coating only comprising AlCrN). This observation points to a less crystalline pattern of AlCrSiN in comparison to AlCrN. No trace of hexagonal crystalline phase, i.e. no trace of hcp phase was identified with the characterization means used, in this case with XRD. This characteristic is advantageous in a broad-band coating for cutting and forming applications. This result was obtained by conducting XRD-analysis including double check XRD theta-2-theta mode with XRD grazing incidence mode. The determination of the presence (or more exactly in this case, the no presence) of hcp was validated in grazing incidence mode. For all XRD measurements in the context of the present description following parameters with a standard Cu anode (45 kV, 40 mA) were used: • Incident angle of 0.5° • Angular step of 0.03° • Duration of each angular step 10 s. Finally, one last advantage from incorporating Si in AlCrN according to the present invention is that it provides a better resistance against high temperature oxidation compared to pure AlCrN. This is especially important for cutting or forming operations conducted in an oxidative atmosphere and in such a manner that high temperatures (e.g. temperatures in a range from 500 °C up to 1500 °C), which occurs typically in dry milling operations. The attained combination of all above-mentioned advantages results in outstanding increased performance in several cutting and forming operations (for example milling, gear cutting and fine blanking, amongst others), what was not possible with the above- mentioned AlCrSiN coatings known from the prior art. According to a further embodiment of the present invention, the inventive coating systems are produced by having layer thickness in advantageous ranges. Concretely, a further improvement of the performance of the inventive coating systems was attained by adjusting the thickness of the transition layer 61, that is joining the bottom layer 40 and the top layer 62. The inventors believe that using an adjusted transition layer thickness according to the present invention, enables giving enough space for the morphological transition, in such a manner that it occurs, from columnar to fine-grained in optimal manner. The use of a Si-containing transition layer 61 as described in the present invention have shown to be key for attaining a coating able to provide outstanding performance in a big variety of applications. As this transition (it means the transition from the columnar morphology to the fine- grained morphology) is also accompanied by a stress transition, this interface might be a weaker spot in the coating. The inventors found that by increasing the thickness of the transition layer would strengthen the connection between the bottom layer and top layer. For example, in one of the coating systems deposited according to the present invention the transition layer was deposited having a layer thickness in a range between 60 and 90 nm, while the total thickness of the whole coating system was between 2.9 µm and 3.1 µm, which results in a very stable and robust coating for many different applications. Thus, a preferred range of thickness of the transition layer was surprisingly in a range from 50 nm to 900 nm. In several tests it was proved that this range provide the necessary effectivity. Experimental examples To show the advantages of the inventive coatings in comparison to non-inventive coatings, inventive coating variants and non-inventive coating variants were deposited on several substrates and corresponding coating characterization as well as different cutting tests were carried out. Different substrates were coated in a coater of the type INNOVENTA kila (an Oerlikon Balzers PVD system) for Examples 1 and 2: • Reference samples consisting of flat and polished stainless steel samples, and flat and polished WC:Co (the nomenclature “WC:Co” is used for referring to cemented carbide comprising tungsten carbide “WC” and cobalt “Co”) samples were coated for conducting standard coating characterization by using known analytical techniques, amongst others: scanning electron microscopy (SEM), X-ray diffractometry (XRD), energy dispersive X-ray composition analysis (EDX), glow discharge optical spectrometry (GDOES), and nanoindentation. • For conducting cutting tests, different cutting tools were coated, amongst others: high speed steel round inserts with a 12 mm diameter, and WC:Co squared endmills with a 10 mm diameter. Example 1: Deposition of non-inventive coating variants: • Coating systems comprising a bottom layer of AlCrN and a top layer of AlCrN were deposited by using reactive cathodic arc PVD techniques, where: • For the deposition of the bottom layer and the top layer, 8 AlCr-targets having chemical element composition corresponding to an Al / Cr ratio in atomic percentage in a range from 2 to 3, in particular in a range from 2.3 to 2.6, were arc-evaporated in a reactive atmosphere comprising nitrogen gas as reactive gas. The nitrogen partial pressure was set at a constant value in a range from 1 Pa up to 5 Pa, in particular between 2 Pa and 4 Pa The substrate temperature was maintained as possible at a constant value in a range from 350 °C up to 600 °C, in particular between 400 °C and 550 °C. A negative bias voltage was applied to the substrates being coated. The only process parameter that was varied during deposition of the coating system was the bias voltage. For the deposition of the bottom layer the negative bias voltage was set to be at a constant value in a range between -20 V and - 70 V, while for the deposition of the top layer the negative bias voltage was increased and set to be higher, at a constant value, preferably at least two times higher in absolute value than it used for the deposition of the bottom layer, where the highest negative bias voltage value used for the deposition of the top layer was not higher than -250 V, in particular it was set to be in a range between -80 V and -200 V. The coating process was not interrupted between the deposition of the bottom layer and the top layer but only the bias was rapidly increased for the deposition of the top layer. Example 2: Deposition of two inventive coating variants and one non inventive coating variant: • Coating systems 100 comprising a bottom layer 40 of AlCrN and an upper layer 60 of AlCrSiN were deposited by using reactive cathodic arc PVD techniques, where: • The bottom layer 40 (non-Si-containing bottom layer 40) was deposited in the same manner as the bottom layer of the non-inventive coating variants described in Example 1. The only difference was that instead of 8 AlCr- targets, only 4 AlCr-targets were used. • The upper layer 60 (Si-containing upper layer 60) was deposited in a similar manner that the top layer of the non-inventive coating variants described in Example 1, but differing in that: - Apart from the same 4 AlCr-targets used for the deposition of the bottom layer 40, additionally 4 AlCrSi-targets were used. - For the non-inventive Example 2.1 the AlCrSi-targets were selected having chemical element composition in atomic percentage 70 / 25 / 5. - For the inventive Examples 2.2. and 2.3 the AlCrSi-targets were selected having Al / Cr / Si chemical element composition in atomic percentage in ranges of Al-content, Cr-content and Si-content so that the ratio Al / (Cr+Si) is maintained in the range 2.3 ≤ Al / (Cr+Si) ≤ 2.6. Following concrete examples will be described as showcases of the present invention: using AlCrSi targets with Al / Cr / Si contents in atomic percentage of 70 / 15 / 15 for inventive Example 2.2, and 70 / 20 / 10 for inventive Example 2.3, respectively. • For the deposition of the upper layer 60, the 8 targets (4 AlCr-targets and 4 AlCrSi-targets as described-above) were arc-evaporated in a reactive atmosphere comprising nitrogen gas as reactive gas with nitrogen pressure and substrate temperature set in the same manner as they were set for the deposition of the bottom layer 40. • Apart from that, the only process parameter that was set to be different during the deposition of the upper layer 60 in comparison to during the deposition of the bottom layer 40 was the negative bias voltage applied to the substrates being coated. • The negative bias voltage used during deposition of the upper layer was set to be variable: - In some cases (corresponding to one embodiment of the present invention) the bias voltage was increased continuously (e.g. in one ramp) or gradually (e.g. in one or more ramps or steps) during deposition of the upper layer 60, wherein the lowest value of the negative bias applied during deposition of the upper layer 60 was equal to it applied for the deposition of the bottom layer 40, and the highest value of negative bias voltage applied during deposition of the upper layer 60 was not higher than -250 V, in particular it (the highest value of negative bias voltage applied) was set to be in a range between -80 V and -200 V. - In other cases (corresponding to other embodiment of the present invention), the absolute value of the negative bias voltage was increased in such a manner that preferably two layers were formed, a transition layer 61 and a top layer 62. In these cases: ^ the transition layer 61 was deposited by setting the bias voltage to vary continuously (e.g. in one ramp) or gradually (e.g. in one or more ramps or steps), from an initial value (lower absolute value) up to a final value (highest absolute value), where the initial value was equal to the negative bias voltage value applied for the deposition of the bottom layer 40 and the final value was equal to the bias voltage applied for the deposition of the top layer 62, and ^ the top layer 62 was deposited by setting the bias voltage to be preferably constant at a value not higher than -250 V, preferably it was set to be in a range between -80 V and -200 V. • The duration of the deposition of the bottom layer 40 and the upper layer 60, or rather of the bottom layer 40, transition layer 61 and top layer 62 was chosen respectively in order to attain the desired layer thicknesses. • The substrates to be coated were hold in corresponding fixtures systems in the middle of the INNOVENTA kila PVD system to have 2-fold or 3-fold rotation in known manner in the interior of the coating chamber, so that the surfaces of the substrates being coated face periodically the corresponding AlCr- and / or AlCrSi-targets hold at the coating chamber walls during deposition of the AlCrN (i.e. the AlCrN bottom layer 40 and the individual AlCrN nanolayers in the upper multi-nanolaminated layer 60 deposited formed of material coming from the AlCr-targets and nitrogen present in the chamber) and AlCrSiN layers (the individual AlCrSiN nanolayers in the upper multi-nanolaminated layer 60 deposited formed of material coming from the AlCrSi-targets and nitrogen present in the chamber), respectively. Figure 4 shows the properties of a preferred inventive coating variant deposited as described in Example 2.3., and shown in Figure 3, comprising a bottom layer 40, and an upper layer 60, and having a total thickness of ca.1.9 µm (measured in a reference substrate coated on 3-fold rotation). The upper layer was deposited comprising a thin transition layer 61 with layer thickness between 50 nm and 75nm, however not clearly visible in the SEM micrographs shown in Figure 3 (left side: backscattered electrons generated picture; right side: secondary electrons generated picture). Cutting tests Cutting operation: wet finishing • Tested in 1.2344 (45HRC) material with square carbide endmills (4 teeth, 10 mm diameter) • Wet conditions • Vc 220 m / min • fz 0.1 mm • ap 10 mm • ae 0.5 mm • Flank wear criteria Vbmax = 100 µm As it is shown if Figure 5a (comparison between coating variant according to non- inventive Example 1 and coating variant according to inventive Example 2.3), the inventive coating variants, in particular as a showcase the variant having coating properties as reported in the table shown in Figure 4 (a coating variant according to inventive Example 2.3), allow an outstanding improvement of more than 75% in terms of tool life in comparison to non-inventive coating variants deposited according to Example 1. More exactly in this case, ca.350 m cut with the inventive coating variant vs.200 m cut with the non-inventive coating variant. The best results in general were attained with the inventive coating variants deposited by using AlCr-targets having Al / Cr chemical element composition in atomic percentage 70 / 30 and AlCrSi-targets having Al / Cr / Si chemical element composition in atomic percentage 70 / 20 / 10 (inventive Example 2.3). The results attained with the non-inventive coating variant deposited by using AlCr- targets having Al / Cr chemical element composition in atomic percentage 70 / 30 and AlCrSi-targets having Al / Cr / Si chemical element composition in atomic percentage 70 / 25 / 5 according to the non-inventive Example 2.1, were not satisfactory in spite of the similar architecture, which indicated the very big relevance of selecting the appropriate chemical element composition for the targets, resulting in the impressive outstanding gut results obtained with the coatings produced according to the present invention. The inventors found that particularly satisfactory results can be obtained when the inventive coatings are prepared by using AlCrSi-targets having Al / Cr ratio of content in atomic percentage higher than 2.8, i.e. when the one or more AlCrSi targets used for producing the AlCrSi individual layers comprised in the Si-containing upper layer 60 fulfill following condition concerning chemical element composition in atomic percentage: AldCreSif, with d+e+f=100, 7 ≥ d / e > 2.8 and 20 ≥ f ≥ 6, more preferably with 6 ≥ d / e ≥ 2.8 and 20 ≥ f ≥ 6. Cutting face milling • Tested in 1.7225 material with round HSS inserts (12 mm diameter) • Dry • Vc 120 m / min • fz 0.4 mm • ap 2 mm • ae 20 mm • Crater wear criteria The inventive coating variant with AlCrSiN shows slower crater formation at initial wear (< 5% of tool life) and slower crater progression for longer distances compared to the non-inventive coatings deposited according to Example 1. As it is shown if Figure 5b, the inventive coating variants, in particular as a showcase the variant having coating properties as reported in the table shown in Figure 4, allow an outstanding slower crater formation at initial wear of less than 5% of tool life, and slower crater progression for longer distances compared to the non-inventive coating variant. All inventive coating variants examined showed better performance than all non- inventive coating variants in the cutting tests that were carried out. Concisely the present invention may relate to: A coated substrate 1 formed of a substrate 10 having a substrate surface to be coated 11 and a coating system 100 deposited on said substrate surface 11, wherein the coating system 100 comprising: • a lower layer 40, and • an upper layer 60, wherein: • the coating system exhibiting: o mixed morphology determined by SEM, comprising at least one layer having columnar morphology and one layer having fine grained morphology (more specifically, the mixed morphology refers to the combination of the lower layer 40 exhibiting columnar morphology and the upper layer 60 exhibiting fine-grained morphology), and o face centered cubic crystal structure determined by X-ray diffraction (XRD) with predominant orientation fcc (200), preferably with ratio of peaks intensity of (111) to (200) in a range corresponding to 0 < I(111) / I(200)< 1, when the total layer thickness is lower than or equal to 3 µm, for example preferably 0.400 ≤ I(111) / I(200) ≤ 0.600, when the total layer thickness is between 1 µm and 2.5 µm, and • the lower layer 40 being an aluminum chromium nitride layer, i.e. an AlCrN layer, exhibiting: o columnar morphology determined by SEM, and • the upper layer 60 being an aluminum chromium silicon nitride layer, i.e. an AlCrSiN layer, exhibiting: o fine grained morphology determined by SEM. If the lower layer 40 where deposited alone on a substrate surface the face centered cubic crystal structure determined by XRD, being preferably with predominant orientation fcc (111), more preferably with ratio of peaks intensity of (111) to (200) in a range corresponding to 1.700 ≤ I(111) / I(200)≤ 1.900. If the upper layer 60 where deposited alone on a substrate surface the face centered cubic crystal structure determined by XRD, being preferably with predominant orientation fcc (200), more preferably with ratio of peaks intensity of (111) to (200) in a range corresponding to 0.200 ≤ I(111) / I(200) ≤ 0.400. A coated substrate 1 formed of a substrate 10 having a substrate surface to be coated 11 and a coating system 100 deposited on said substrate surface 11, wherein the coating system 100 comprising: • a lower layer 40, and • an upper layer 60, wherein: • the coating system exhibiting: o mixed morphology determined by SEM, comprising at least one layer having columnar morphology and one layer having fine grained morphology (more specifically, the mixed morphology refers to the combination of the lower layer 40 exhibiting columnar morphology and the upper layer 60 exhibiting fine-grained morphology), and o face centered cubic crystal structure determined by X-ray diffraction (XRD) with predominant orientation fcc (111), preferably with ratio of peaks intensity of (111) to (200) in a range corresponding to 1 < I(111) / I(200) < 2, when the total layer thickness is higher than 3 µm, preferably when the total layer thickness is higher than 3.5 µm, more preferably when the total layer thickness is higher than or equal to 4 µm, and • the lower layer 40 being an aluminum chromium nitride layer, i.e. an AlCrN layer, exhibiting: o columnar morphology determined by SEM, and • the upper layer 60 being an aluminum chromium silicon nitride layer, i.e. an AlCrSiN layer, exhibiting: o fine grained morphology determined by SEM. Figure 6 shows the behavior of the ratio of peaks intensity of (111) to (200) for one inventive coating system (according to the inventive Example 2.3) deposited with different thicknesses of the total coating system. Similar behaviors were observed in all inventive coating systems. Not all inventive coating systems deposited are described in detail in the present invention but just some inventive Examples. These inventive Examples should therefore not be considered as a limitation of the present invention but as showcases of the present invention. In a preferred embodiment of a coated substrate according to the present invention: • the lower layer (40) having chemical element composition in atomic concentration, determined by (EDX) composition analysis, corresponding to following formula (AlxCr1-x)aNb, with 0.50 ≤ x ≤ 0.80, preferably with 0.60 ≤ x ≤ 0.75, more preferably with 0.64 ≤ x ≤ 0.74, and 0.85 ≤ a / b ≤ 1.15, and preferably 1.5 ≤ x / (1-x) ≤ 2.9, and • the upper layer (60) having chemical element composition in atomic concentration, determined by EDX, corresponding to following formula (AlyCrvSiz)dNe, whith y+v+z=1, and 0.7 ≤ 0.25 y / v ≤ 0.9, and 0.01 ≤ z ≤ 0.10, and 0.85 ≤ d / e ≤ 1.15. In a further preferred embodiment of a coated substrate according to the present invention: • the coating system (100) having average crystallite, determined by XRD, in the crystal structure fcc (111) and / or in the crystal structure fcc (200) in a range from 200 Å up to 400 Å. Preferably the coating system 100 is produced having hardness HIT, determined by nanoindentation, in a range from 35 GPa and 48 GPa. More preferably the coating system 100 is produced having Young’s modulus EIT, determined by nanoindentation, in a range from 300 GPa up to 480 GPa, still more preferably from 350 GPa up to 450 GPa. The coated substrate was especially advantageous as being produced with a coating system 100 having residual compressive stress, determined by bending, in a range from -2.0 GPa up to -5.5 GPa, preferably from -2.5 GPa up to -5.0 GPa. Preferably the upper layer 60 is produced: • comprising a transition region 61 and a top region 62, both exhibiting compressive residual stress, wherein the compressive residual stress in absolute value in the transition region 61 is lower than the compressive residual stress in absolute value in the top region 62 preferably is lower in at least 0.5 GPa, more preferably is lower in a value in a range from 1.0 GPa up to 3.0 GPa, still more preferably in a range from 1.5 GPa up to 2.5 GPa, and / or • preferably the average silicon concentration in the transition region 61 is higher than the average silicon concentration in the top region 62, when measured by using secondary ion mass spectrometry (SIMS) or glow discharge optical spectrometry (GDOES) techniques. The coated tools according to the present invention show particularly good performance when: • the thickness of the upper layer 60 is in a range from 300 nm up to 10 µm, and / or • the thickness of the lower layer 40 is in a range from 100 nm up to 5 µm. According to a very preferred embodiment of the present invention the upper layer 60 is deposited directly atop the lower layer 40. Preferably: • the transition region 61 is deposited directly atop the lower layer 40 having a thickness that extends from the outermost surface of the lower layer 40 in direction to the outermost surface of the upper layer 60, until a point in the thickness of the upper layer 60, wherein the thickness of the transition region 61 is at least 20 % lower than the thickness of the upper layer 60, and wherein said transition region thickness is preferably in a range from 50 nm up to 5 µm, more preferably in a range from 200 nm up to 2 µm. According to one further preferred embodiment of the present invention the top region 62 is deposited directly atop the transition region 61 having a thickness that extends from the outermost surface of the transition region 61 up to the outermost surface of the upper layer 60, wherein the thickness of the top region 62 is at least 20 % greater than the thickness of the transition region 61, and wherein said top region thickness is preferably in a range from 200 nm up to 10 µm, more preferably in a range from 500 nm up to 5 µm. The present invention relates likewise to a method for producing a coated substrate 1 according to any of the preceding embodiments, wherein, the method comprising following steps: • providing a substrate 10 having a substrate surface 11 to be coated, • depositing the lower layer 40 of AlCrN on the substrate surface 11 by using reactive cathodic arc physical vapor deposition techniques, thereby using nitrogen gas as reactive gas and operating at least one AlCr-target as cathode for obtaining the aluminum and chromium used to react with nitrogen, in this manner forming the lower layer 40 of AlCrN, • depositing the upper layer 60 of AlCrSiN above the lower layer 40 by using reactive cathodic arc physical vapor deposition techniques, thereby using nitrogen gas as reactive gas and operating at least one AlCrSi-target, or at least one AlCr-target and at least one AlCrSi-target, as cathode for obtaining the aluminum, chromium and silicon used to react with nitrogen, in this manner forming the upper layer 60 of AlCrSiN, • wherein a negative bias voltage is applied to the substrate 10 during deposition of the coating system 100: o the bias voltage applied during deposition of the lower layer 40, Vlower, is maintained constant or is varied, i.e. increased and / or reduced during deposition of the lower layer 40, and o the bias voltage applied during deposition of the upper layer 60, Vupper, is maintained constant or is varied, i.e. increased and / or reduced during deposition of the upper layer 60, wherein: o the average bias voltage in absolute value applied during deposition of the upper layer (60), │Vupper_average│, is higher than the average bias voltage in absolute value applied during deposition of the lower layer (40), preferably at least two-times higher, i.e. According to a preferred embodiment of the method according to the present invention: • the bias voltage applied during deposition of the lower layer 40 is applied in such a manner that an initial value │Vlower_initial│ is applied at the beginning of the deposition of the lower layer 40 and a final value │Vlower_final│ is applied at the end of the deposition of the lower layer 40, wherein: o │Vlower_initial│ = │Vlower_final│ or │Vlower_initial│ ≠ │Vlower_final│, and o │Vlower_initial│ and │Vlower_final│ in a range from 0 V up to 80 V, preferably from 20 V up to 60 V, and • the bias voltage applied during deposition of the upper layer 60 is applied in such a manner that an initial value │Vupper_initial│ is applied at the beginning of the deposition of the upper layer 60 and a final value │Vupper_final│ is applied at the end of the deposition of the upper layer 60, wherein o │Vupper_initial│ < │Vupper_final│, and o │Vupper_initial│ and │Vupper_final│ in a range from 20 V up to 250 V, preferably from 30 V up to 200 V Preferably: • the bias voltage applied during deposition of the upper layer 60 is applied in such a manner that at least a transition region 61 and a top region 62 is produced, wherein: o the transition region is deposited by applying at the beginning the initial value │Vupper_initial│ and at the end a middle │Vupper_middle│, wherein: ^ │Vupper_middle│ > │Vupper_initial│, and ^ │Vupper_middle│ ≤ │Vupper_final│. More preferably the method is conducted selecting the bias voltage value to be applied so that │Vlower_final│ ≤ All above-described examples and embodiments should not be understood as a limitation of the present invention but as showcases and preferred embodiments. In this regard, for example it is possible that the bottom layer of a coating system according to the present invention be deposited by applying a variable bias voltage. In the context of the present invention is of great importance that the upper layer 60, in particular the top layer 62 be deposited as function layer. It means that this layer should be available in the coated substrate (for example cutting tool or forming tool coated with the inventive coating system 100) in such a manner that this layer can be in direct contact with the workpiece being processed during the corresponding application (e.g. cutting application or forming application). Therefore, it is strong recommendable that the upper layer 60 be deposited as outermost layer of the coated substrate, consequently as outermost layer of the coating system 100, as it is shown in Figures 1 and 2. Thus, the present invention provides concretely: A coated substrate 1 formed of a substrate 10 having a substrate surface to be coated 11 and a coating system 100 deposited on said substrate surface 11, wherein the coating system 100 comprising: • a lower layer 40, and • an upper layer 60, wherein: • the coating system exhibiting mixed morphology determined by SEM, wherein: o the lower layer 40 is an aluminum chromium nitride layer exhibiting columnar morphology determined by SEM, and o the upper layer (60) is a multilayer formed of a plurality of individual aluminum chromium nitride layers and individual aluminum chromium silicon nitride layers deposited alternate one on each other, having fine grained morphology determined by SEM, and • the upper layer (60) deposited directly atop the lower layer (40), as outermost layer of the coating system (100), and • the coating system exhibiting face centered cubic crystal structure determined by XRD, wherein the face centered cubic crystal structure exhibiting: o predominant orientation fcc (200) with ratio of peaks intensity of (111) to (200) in a range corresponding to 0 < I(111) / I(200) < 1, or o predominant orientation fcc (111), with ratio of peaks intensity of (111) to (200) in a range corresponding to 1 < I(111) / I(200)< 2. The coated substrate 1 according to the present invention may allow attaining in the coating system 100 a combination of mechanical properties characterized by: • a hardness HIT, determined by nanoindentation, in a range from 35 GPa and 48 GPa, and • a Young’s modulus EIT, determined by nanoindentation, in a range from 300 GPa up to 480 GPa, preferably from 350 GPa up to 450 GPa. The coated substrate 1 according to a very preferred embodiment of the present invention is provided with the coating system 100 having: • the lower layer (40) having chemical element composition in atomic concentration, determined by EDX composition analysis, corresponding to the formula (AlxCr1-x)aNb, with 0.50 ≤ x ≤ 0.80, preferably with 0.60 ≤ x ≤ 0.75, more preferably with 0.64 ≤ x ≤ 0.74, and 0.85 ≤ a / b ≤ 1.15, and preferably 1.5 ≤ x / (1-x) ≤ 2.9, and • the upper layer (60) having chemical element composition in atomic concentration, determined by EDX, corresponding to following formula (AlyCrvSiz)dNe, whith y+v+z=1, and 0.7 ≤ 0.25 y / v ≤ 0.9, and 0.01 ≤ z ≤ 0.10, and 0.85 ≤ d / e ≤ 1.15. The coating system (100) is preferably provided according to the present invention having; • predominant orientation fcc (200) with ratio of peaks intensity of (111) to (200) in a range corresponding to 0 < I(111) / I(200)< 1 when the total layer thickness lower than or equal to 3 µm, or • predominant orientation fcc (200) with ratio of peaks intensity of (111) to (200) in a range corresponding to 0.400 ≤ I(111) / I(200)≤ 0.600 when the total layer thickness in a range from 1 µm to 2.5 µm, or • predominant orientation fcc (111) with ratio of peaks intensity of (111) to (200) in a range corresponding to 1 < I(111) / I(200) < 2 when the total layer thickness higher than 3 µm, preferably higher than 3.5 µm, more preferably higher than or equal to 4 µm. Further the coating system 100 is preferably provided having average crystallite, determined by XRD, in the crystal structure fcc (111) and / or in the crystal structure fcc (200) in a range from 200 Å up to 400 Å. Further the coating system 100 is preferably provided having having residual compressive stress, determined by bending, in a range from -2.0 GPa up to -5.5 GPa, preferably from -2.5 GPa up to -5.0 GPa. According to a very preferred embodiment of the present invention, the coated substrate 1 is provided in such a manner that the upper layer 60 comprising a transition region 61 and a top region 62, both exhibiting compressive residual stress, wherein the compressive residual stress in absolute value in the transition region 61 is lower than the compressive residual stress in absolute value in the top region 62, and preferably is lower in at least 0.5 GPa, more preferably is lower in a value in a range from 1.0 GPa up to 3.0 GPa, still more preferably in a range from 1.5 GPa up to 2.5 GPa, and / or preferably the average silicon concentration in the transition region 61 is higher than the average silicon concentration in the top region 62, when measured by using secondary ion mass spectrometry (SIMS) or glow discharge optical spectrometry (GDOES) techniques. Preferably the thickness of the upper layer 60 is in a range from 300 nm up to 10 µm, and / or the thickness of the lower layer 40 is in a range from 100 nm up to 5 µm. Preferably the upper layer 60 is deposited directly atop the lower layer 40. The transition region 61 is preferably deposited directly atop the lower layer 40 having a thickness that extends from the outermost surface of the lower layer 40 in direction to the outermost surface of the upper layer 60, until a point in the thickness of the upper layer 60, in such a manner that the thickness of the transition region 61 be at least 20 % lower than the thickness of the upper layer 60, and preferably said transition region thickness in a range from 50 nm up to 5 µm, in some cases more preferably in a range from 200 nm up to 2 µm. The top region 62 is deposited directly atop the transition region 61 having preferably a thickness that extends from the outermost surface of the transition region 61 up to the outermost surface of the upper layer 60, in such a manner that the thickness of the top region 62 is at least 20 % greater than the thickness of the transition region 61, and said top region thickness is preferably in a range from 200 nm up to 10 µm, more preferably in a range from 500 nm up to 5 µm. The thickness of the lower layer 40 is preferably between 20% and 60% of the total thickness of the coating system 100 and the thickness of the upper layer 60 is also preferably between 30% and 80% of the total thickness of the coating system 100. The coating system 100 is preferably formed solely of the lower layer 40 and the upper layer 60. It has the advantage that all essential elements of the coating system 100 are present and additional, unnecessary layers are avoided. The coated substrate is preferably a tool for cutting and / or forming applications, because the present invention has shown to be especially advantageous and suitable for increasing tool performance in a big variety of cutting and forming applications. A preferred embodiment of a method for producing a coated substrates 1 according to the present invention comprises following steps: • providing a substrate 10 having a substrate surface 11 to be coated, • depositing the lower layer 40 of AlCrN on the substrate surface 11 by using reactive cathodic arc physical vapor deposition techniques, thereby using nitrogen gas as reactive gas and operating at least one AlCr-target as cathode for obtaining the aluminum and chromium used to react with nitrogen, in this manner forming the lower layer 40 of AlCrN, • depositing the upper layer 60 of AlCrN and AlCrSiN above the lower layer 40 by using reactive cathodic arc physical vapor deposition techniques, thereby using nitrogen gas as reactive gas and operating at least one AlCrSi-target, or at least one AlCr-target and at least one AlCrSi-target, as cathode for obtaining the aluminum, chromium and silicon used to react with nitrogen, in this manner forming the upper layer 60 of AlCrSiN, • wherein: o the AlCr-targets having Al / Cr chemical element composition in atomic percentage in ranges of Al-content and Cr-content so that the ratio Al / Cr is maintained in the range 2 ≤ Al / Cr ≤ 3, preferably 2.3 ≤ Al / Cr ≤ 2.6, and o the AlCrSi-targets having Al / Cr / Si chemical element composition in atomic percentage in ranges of Al-content, Cr-content and Si-content so that the ratio Al / (Cr+Si) is maintained in the range 2.3 ≤ Al / (Cr+Si) ≤ 2.6, and • wherein a negative bias voltage is applied to the substrate 10 during deposition of the coating system 100: o the bias voltage applied during deposition of the lower layer 40, Vlower, is maintained constant or is varied, i.e. increased and / or reduced during deposition of the lower layer 40, and o the bias voltage applied during deposition of the upper layer 60, Vupper, is maintained constant or is varied, i.e. increased and / or reduced during deposition of the upper layer 60, wherein: o the average bias voltage in absolute value applied during deposition of the upper layer 60, │Vupper_average│, is higher than the average bias voltage in absolute value applied during deposition of the lower layer 40, preferably at least two-times higher, i.e. The AlCrSi-targets preferably having chemical element composition in atomic percentage: AldCreSif, with d+e+f=100, 7 ≥ d / e > 2.8 and 20 ≥ f ≥ 6, more preferably with 6 ≥ d / e ≥ 2.8 and 20 ≥ f ≥ 6. The inventive method is preferably conducted by varying the bias voltage as following explained in order to create a coating structure appropriate for applications in which micro-fissures within the coating could be produced: • the bias voltage applied during deposition of the lower layer (40) is applied in such a manner that an initial value │Vlower_initial│ is applied at the beginning of the deposition of the lower layer (40) and a final value │Vlower_final│ is applied at the end of the deposition of the lower layer (40), wherein: o │Vlower_initial│ = │Vlower_final│ or │Vlower_initial│ ≠ │Vlower_final│, and o │Vlower_initial│ and │Vlower_final│ in a range from 0 V up to 80 V, preferably from 20 V up to 60 V, and • the bias voltage applied during deposition of the upper layer (60) is applied in such a manner that an initial value │Vupper_initial│ is applied at the beginning of the deposition of the upper layer (60) and a final value │Vupper_final│ is applied at the end of the deposition of the upper layer (60), wherein o │Vupper_initial│ < │Vupper_final│, and o │Vupper_initial│ and │Vupper_final│ in a range from 20 V up to 250 V, preferably from 30 V up to 200 V More preferably the bias voltage applied during deposition of the upper layer (60) is applied in such a manner that at least a transition region (61) and a top region (62) is produced, wherein: o the transition region is deposited by applying at the beginning the initial value │Vupper_initial│ and at the end a middle │Vupper_middle│, wherein: ^ │Vupper_middle│ > │Vupper_initial│, and ^ │Vupper_middle│ ≤ │Vupper_final│. Still more preferably wherein: ^ │Vlower_final│ ≤ │Vupper_initial│, and / or ^ │Vupper_middle│ = │Vupper_final│.

Claims

Claims 1. A coated substrate (1) formed of a substrate (10) having a substrate surface to be coated (11) and a coating system (100) deposited on said substrate surface (11), wherein the coating system (100) comprising: • a lower layer (40), and • an upper layer (60), characterized in that: • the coating system exhibiting mixed morphology determined by SEM, wherein: o the lower layer (40) is an aluminum chromium nitride layer exhibiting columnar morphology determined by SEM, and o the upper layer (60) is a multilayer formed of a plurality of individual aluminum chromium nitride layers and individual aluminum chromium silicon nitride layers deposited alternate one on each other, having fine grained morphology determined by SEM, and • the upper layer (60) deposited directly atop the lower layer (40), as outermost layer of the coating system (100), and • the coating system exhibiting face centered cubic crystal structure determined by XRD, wherein the face centered cubic crystal structure exhibiting: o predominant orientation fcc (200) with ratio of peaks intensity of (111) to (200) in a range corresponding to 0 < I(111) / I(200) < 1, or o predominant orientation fcc (111), with ratio of peaks intensity of (111) to (200) in a range corresponding to 1 < I(111) / I(200)< 2.

2. The coated substrate (1) according claim 1, characterized in that the coating system (100) having: • hardness HIT, determined by nanoindentation, in a range from 35 GPa and 48 GPa, and • having Young’s modulus EIT, determined by nanoindentation, in a range from 300 GPa up to 480 GPa, preferably from 350 GPa up to 450 GPa.

3. The coated substrate (1) according to at least one of the preceding claims 1 to 2, characterized in that the coating system (100) having: • the lower layer (40) having chemical element composition in atomic concentration, determined by EDX composition analysis, corresponding to the formula (AlxCr1-x)aNb, with 0.50 ≤ x ≤ 0.80, preferably with 0.60 ≤ x ≤ 0.75, more preferably with 0.64 ≤ x ≤ 0.74, and 0.85 ≤ a / b ≤ 1.15, and preferably 1.5 ≤ x / (1-x) ≤ 2.9, and • the upper layer (60) having chemical element composition in atomic concentration, determined by EDX, corresponding to following formula (AlyCrvSiz)dNe, whith y+v+z=1, and 0.7 ≤ 0.25 y / v ≤ 0.9, and 0.01 ≤ z ≤ 0.10, and 0.85 ≤ d / e ≤ 1.

15.

4. The coated substrate (1) according to at least one of the preceding claims 1 to 3, characterized in that the coating system (100) having: • predominant orientation fcc (200) with ratio of peaks intensity of (111) to (200) in a range corresponding to 0 < I(111) / I(200)< 1 and total layer thickness lower than or equal to 3 µm, or • predominant orientation fcc (200) with ratio of peaks intensity of (111) to (200) in a range corresponding to 0.400 ≤ I(111) / I(200)≤ 0.600 and total layer thickness in a range from 1 µm to 2.5 µm, or • predominant orientation fcc (111) with ratio of peaks intensity of (111) to (200) in a range corresponding to 1 < I(111) / I(200) < 2 and total layer thickness higher than 3 µm, preferably higher than 3.5 µm, more preferably higher than or equal to 4 µm.

5. The coated substrate (1) according to at least one of the preceding claims 1 to 4, characterized in that: • the coating system (100) having average crystallite, determined by XRD, in the crystal structure fcc (111) and / or in the crystal structure fcc (200) in a range from 200 Å up to 400 Å.

6. The coated substrate (1) according to at least one of the preceding claims 1 to 5, characterized in that: • the coating system (100) having residual compressive stress, determined by bending, in a range from -2.0 GPa up to -5.5 GPa, preferably from -2.5 GPa up to -5.0 GPa.

7. The coated substrate (1) according to at least one of the preceding claims 1 to 6, characterized in that: • the upper layer (60) comprising a transition region (61) and a top region (62), both exhibiting compressive residual stress, wherein the compressive residual stress in absolute value in the transition region (61) is lower than the compressive residual stress in absolute value in the top region (62) preferably is lower in at least 0.5 GPa, more preferably is lower in a value in a range from 1.0 GPa up to 3.0 GPa, still more preferably in a range from 1.5 GPa up to 2.5 GPa, and / or • preferably the average silicon concentration in the transition region (61) is higher than the average silicon concentration in the top region (62), when measured by using secondary ion mass spectrometry (SIMS) or glow discharge optical spectrometry (GDOES) techniques.

8. The coated substrate (1) according to at least one of the preceding claims 1 to 7, characterized in that: • the thickness of the upper layer (60) is in a range from 300 nm up to 10 µm, and / or • the thickness of the lower layer (40) is in a range from 100 nm up to 5 µm.

9. The coated substrate (1) according to at least one of the preceding claims 1 to 8, characterized in that: • the upper layer (60) is deposited directly atop the lower layer (40).

10. The coated substrate (1) according to at least one of the preceding claims 7 to 9, characterized in that:• the transition region (61) is deposited directly atop the lower layer (40) having a thickness that extends from the outermost surface of the lower layer (40) in direction to the outermost surface of the upper layer (60), until a point in the thickness of the upper layer (60), wherein the thickness of the transition region (61) is at least 20 % lower than the thickness of the upper layer (60), and wherein said transition region thickness is preferably in a range from 50 nm up to 5 µm, more preferably in a range from 200 nm up to 2 µm.

11. The coated substrate (1) according to claim 10, characterized in that: • the top region (62) is deposited directly atop the transition region (61) having a thickness that extends from the outermost surface of the transition region (61) up to the outermost surface of the upper layer (60) , wherein the thickness of the top region (62) is at least 20 % greater than the thickness of the transition region (61), and wherein said top region thickness is preferably in a range from 200 nm up to 10 µm, more preferably in a range from 500 nm up to 5 µm.

12. The coated substrate (1) according to any of the preceding claims 1 to 11, characterized in that: • the thickness of the lower layer (40) is between 20% and 60% of the total thickness of the coating system (100) and the thickness of the upper layer (60) is between 30% and 80% of the total thickness of the coating system (100).

13. The coated substrate (1) according to any of the preceding claims 1 to 12, characterized in that: • the coating system (100) is formed of the lower layer (40) and the upper layer (60).

14. The coated substrate (1) according to any of the preceding claims 1 to 13, characterized in that: • the substrate is a tool for cutting and / or forming applications.

15. A method for producing a coated substrate (1) according to any of the preceding claims 1 to 14, characterized in that, the method comprising following steps: • providing a substrate (10) having a substrate surface (11) to be coated, • depositing the lower layer (40) of AlCrN on the substrate surface (11) by using reactive cathodic arc physical vapor deposition techniques, thereby using nitrogen gas as reactive gas and operating at least one AlCr-target as cathode for obtaining the aluminum and chromium used to react with nitrogen, in this manner forming the lower layer (40) of AlCrN, • depositing the upper layer (60) of AlCrN and AlCrSiN above the lower layer (40) by using reactive cathodic arc physical vapor deposition techniques, thereby using nitrogen gas as reactive gas and operating at least one AlCrSi- target, or at least one AlCr-target and at least one AlCrSi-target, as cathode for obtaining the aluminum, chromium and silicon used to react with nitrogen, in this manner forming the upper layer (60) of AlCrSiN, • wherein: o the AlCr-targets having Al / Cr chemical element composition in atomic percentage in ranges of Al-content and Cr-content so that the ratio Al / Cr is maintained in the range 2 ≤ Al / Cr ≤ 3, preferably 2.3 ≤ Al / Cr ≤ 2.6, and o the AlCrSi-targets having Al / Cr / Si chemical element composition in atomic percentage in ranges of Al-content, Cr-content and Si-content so that the ratio Al / (Cr+Si) is maintained in the range 2.3 ≤ Al / (Cr+Si) ≤ 2.6, and • wherein a negative bias voltage is applied to the substrate (10) during deposition of the coating system (100): o the bias voltage applied during deposition of the lower layer (40), Vlower,is maintained constant or is varied, i.e. increased and / or reduced during deposition of the lower layer (40), and o the bias voltage applied during deposition of the upper layer (60), Vupper,is maintained constant or is varied, i.e. increased and / or reduced during deposition of the upper layer (60), wherein:o the average bias voltage in absolute value applied during deposition of the upper layer (60), │Vupper_average│, is higher than the average bias voltage in absolute value applied during deposition of the lower layer (40),preferably at least two-times higher, i.e.

16. The method according to claim 15, characterized in that: o the AlCrSi-targets having chemical element composition in atomic percentage: AldCreSif, with d+e+f=100, 7 ≥ d / e > 2.8 and 20 ≥ f ≥ 6, more preferably with 6 ≥ d / e ≥ 2.8 and 20 ≥ f ≥ 6.

17. The method according to any of the preceding claims 15 to 16, characterized in that: • the bias voltage applied during deposition of the lower layer (40) is applied in such a manner that an initial value │Vlower_initial│ is applied at the beginning of the deposition of the lower layer (40) and a final value │Vlower_final│ is applied at the end of the deposition of the lower layer (40), wherein: o │Vlower_initial│ = │Vlower_final│ or │Vlower_initial│ ≠ │Vlower_final│, and o │Vlower_initial│ and │Vlower_final│ in a range from 0 V up to 80 V, preferably from 20 V up to 60 V, and • the bias voltage applied during deposition of the upper layer (60) is applied in such a manner that an initial value │Vupper_initial│ is applied at the beginning of the deposition of the upper layer (60) and a final value │Vupper_final│ is applied at the end of the deposition of the upper layer (60), whereinrange from 20 V up to 250 V, preferably from 30 V up to 200 V 18. The method according to claim 17, characterized in that: • the bias voltage applied during deposition of the upper layer (60) is applied in such a manner that at least a transition region (61) and a top region (62) is produced, wherein:o the transition region is deposited by applying at the beginning the initial value │Vupper_initial│ and at the end a middle │Vupper_middle│, wherein: ^ │Vupper_middle│ > │Vupper_initial│, and ^ │Vupper_middle│ ≤ │Vupper_final│.

19. The method according to claim 18, characterized in that: • │Vlower_final│ ≤ │Vupper_initial│, and / or

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