Tool or wear part and coating method to deposit a coating on a tool or wear part

Abstract

The present disclosure relates to a tool or wear part and coating method to deposit a coating on a tool or wear part. It is disclosed a tool or wear part comprising a coating over a hardmetal substrate, in particular on the surface of the tool or wear part, wherein the coating is a multilayer, a first titanium layer comprising titanium carbonitride; a second layer comprising aluminium oxide; a titanium coating layer lodged over the second layer and a first top layer comprising AlCrN or AlCrN / ZrN deposited though physical vapour deposition.

Description

D E S C R I P T I O NTOOL OR WEAR PART AND COATING METHOD TO DEPOSIT A COATING ON A TOOL OR WEAR PARTTECHNICAL FIELD

[0001] The present disclosure relates to a tool or wear part and coating method to deposit a coating on a tool or wear part.BACKGROUND

[0002] When it comes to coating tools or wear parts, there are several common issues and challenges to be solved. Some of the main ones include the adhesion promotion, wear resistance, thickness control, coating integrity and defects, cost -effectiveness and environmental considerations.

[0003] To address these challenges, material science engineers employ various techniques such as physical vapor deposition (PVD), chemical vapor deposition (CVD), thermal spray, electroplating, and advanced coating materials like diamond-like carbon (DLC), ceramic coatings, or composite coatings. They also conduct extensive testing, characterization, and analysis to ensure the quality and performance of the coated products.

[0004] Nevertheless, in what concerns adhesion promotion, achieving strong adhesion between the coating and the substrate is crucial for the durability and performance of the coated part. Poor adhesion can lead to coating delamination or flaking, resulting in premature failure of the component.

[0005] This is even more important when it comes with the machining of heat- resistant alloys. In these cases, achieving strong adhesion between the tool material and the workpiece is a critical factor for successful machining operations. However, several challenges can arise in the adhesion process, namely high cutting temperatures, chemical reactivity, diffusion, tool wear and deformation and cutting forces and vibrations.

[0006] The main issue with the high cutting temperatures is that heat-resistant alloys are known for their ability to withstand elevated temperatures, which makes them challenging to machine. The high temperatures generated during machining can lead to thermal softening of the tool material and workpiece, causing increased tool wear and reduced adhesion at the tool-workpiece interface. In another point of view, heat- resistant alloys often exhibit high chemical reactivity with tool materials at elevated temperatures. This reactivity can result in the formation of intermetallic compounds or chemical reactions between the tool and workpiece, leading to poor adhesion and tool failure. Machining heat-resistant alloys can cause severe tool wear due to the combination of high cutting temperatures, abrasion, and adhesion forces. Tool wear and deformation can lead to a decrease in the effective contact area between the tool and workpiece, resulting in reduced adhesion. Diffusion plays a significant role in the adhesion process. At high temperatures, atoms from the tool material can diffuse into the workpiece material, and vice versa, altering the surface properties and creating diffusion layers. Excessive diffusion can weaken the adhesion between the tool and the workpiece, reducing machining performance. Heat-resistant alloys are then typically hard and difficult to machine, leading to higher cutting forces and vibrations during machining operations. These forces and vibrations can affect the adhesion process by inducing micro-scale or macro-scale movements at the tool-workpiece interface, potentially leading to poor adhesion and surface finish.

[0007] To address these challenges, the prior art employs various strategies, including the tool material selection, i.e. choosing a suitable tool material with high temperature resistance, chemical inertness, and wear resistance is crucial. Advanced tool materials such as carbide inserts, ceramic inserts, or coated tool materials, e.g., PVD or CVD coatings, are often used to improve adhesion and tool life. It is also very important to adjust the cutting parameters such as cutting speed, feed rate, and depth of cut can help manage the cutting temperature, reduce chemical reactivity, and control diffusion, thus improving adhesion. Also, the use of suitable lubricants or coolants can help control temperatures, reduce friction, and mitigate tool wear, thus improving adhesion.

[0008] Another way of address the challenges previously discussed is by applying appropriate coatings on the tool surfaces that can enhance adhesion and reduce friction and wear. Coatings like titanium nitride (TiN), titanium aluminium nitride (TiAIN), or aluminium titanium nitride (AITiN) are commonly used for improved performance in machining heat-resistant alloys.

[0009] Advanced machining techniques like cryogenic machining, high-speed machining, or laser-assisted machining can also be employed to manage cutting temperatures and enhance adhesion, but they are economically expensive.

[0010] By addressing these issues and employing appropriate strategies, material science engineers can improve the adhesion process during the machining of heat- resistant alloys, leading to more efficient and reliable machining operations.

[0011] In the document CN114318226A, it is disclosed a protective coating for cutting tools, disclosing an AICrN / WN multilayer structure hard coating for titanium alloy cutting as well as a preparation method and application of the AICrN / WN multilayer structure hard coating. The disclosed multi-layer AICrN / WN coating is compositely deposited by adopting arc ion plating and a direct current magnetron sputtering technology, and the coating comprises an AICrN transition layer directly combined with a cutter base body, an AICrN / WN composite multi-layer and a WN top layer on the outermost side; and the AICrN / WN composite multilayer is formed by alternately depositing an electric arc AICrN layer and a sputtering WN layer. According to the method described in said document, the fracture toughness of the coating of the cutter is improved through the multi-layer design, the vibration of the cutter during titanium alloy cutting machining is effectively reduced, the propagation of surface micro cracks during machining is improved, and the reactivity of a machined material and the surface of the cutter is reduced, so that the service life of the coated cutter is prolonged, and the prepared coated cutter is suitable for machining titanium alloy.

[0012] In the document CN104131256A, it is disclosed a multilayer nanometer composite cutting tool coating and a preparation method thereof. The surface of a cutting tool substrate is coated with a titanium nitride transition layer by using physical vapor deposition technology and is then alternately and periodically coated by multiple layers of an aluminium-titanium-silicon nitride coating and an aluminium-chromium-nitrogen coating, wherein the thickness of the titanium nitride transition layer is 0.1 to 0.5 urn, the thickness of each layer of the aluminium-titanium-silicon nitride coating and the aluminium-chromium-nitrogen coating is 0.1 to 0.5 urn, and the substrate is coated by 4 to 20 layers, thereby forming the AITiSiN / AICrN nanometer composite cutting tool coating with a multilayer structure. According to the invention, the crystal size of the coating is in a range of 5 to 15 nm, the total thickness of the coating is 1 to 6 pm, the microscopic hardness of the coating is 25 to 40 GPa, and high temperature stability reaches more than 1050°C. A cutting tool prepared by using the coating has greatly improved resistance to mechanical wear and high temperature oxidation resistance and can meet demands of high speed processing for better performance of a cutting tool material.

[0013] Tools and wear parts used in industries such as manufacturing, mining, automotive, and aerospace often experience wear and corrosion, leading to reduced efficiency and increased maintenance costs. The development of advanced coating methods is crucial to mitigate these issues and extend the service life of these tools.

[0014] These facts are disclosed in order to illustrate the technical problem addressed by the present disclosure.GENERAL DESCRIPTION

[0015] The present disclosure relates to a tool or wear part and coating method to deposit a coating on a tool or wear part.

[0016] The present disclosure describes an innovative method for depositing coatings on tools and wear parts to enhance their performance, durability, and overall lifespan. The proposed coating method employs different technologies and materials to address common wear and corrosion challenges and durability in various industrial applications.

[0017] The present disclosure comprises a tool or wear part comprising a coating over a hard metal substrate, such as a tungsten carbide-cobalt substrate, in particular on the surface of the tool or wear part, wherein the coating is a multilayer, a first titanium layer comprising titanium carbonitride, a second layer comprising aluminium oxide; atitanium nitride coating layer lodged over the second layer and a top layer comprising AICrN deposited though physical vapour deposition.

[0018] The main problem overcomed by the present solution is that when using the prior art technologies, namely the coated tools with multilayer coatings based in titanium carbonitride (TiCN) and alumina (AI2O3) deposited by CVD in the machining of heat-resistant alloys, there is a high probability of coating degradation and accelerated failure of the tool. Furthermore, the geometric features of the tool or wear part do not influence the multilayer coating adhesion, which is a main advantage over the prior art.

[0019] The TiCN coating also provides additional advantages, such as a very hard and resistant layer, with a fine particle size with crystal control technology enabling a n improved chipping resistance.

[0020] The alumina coating was improved and developed to be an industry leading standard for crystal growth and densification on AI2O3 layer. This nano control technology increases tool life and wear resistance due to the fine, dense crystal growth process. The TiN layer improves surface roughness and adhesion to AICrN top layer, this last coating possesses high thermal shock resistance and corrosion resistance.

[0021] The multilayer coating titanium nitride (TiN), titanium carbonitride (TiCN), alumina (AI2O3) and titanium nitride (TiN) is deposited by chemical vapour deposition (CVD), while aluminium chromium nitride (AICrN) is deposited though physical vapour deposition (PVD) using high-power impulse magnetron sputtering (HiPIMS) technologies.

[0022] Along this text, it is considered that high-power impulse magnetron sputtering (HiPIMS) is a method for physical vapor deposition of thin films which is based on magnetron sputter deposition. HiPIMS uses extremely high power densities of the order of kW-crrr2in short pulses (impulses) of tens of microseconds at low duty cycle (on / off time ratio) of < 10%. Distinguishing features of HiPIMS are a high degree of ionization of the sputtered metal and a high rate of molecular gas dissociation which result in high density of deposited films. The ionization and dissociation degree increase according to the peak cathode power. The limit is determined by thetransition of the discharge from glow to arc phase. The peak power and the duty cycle are selected so as to maintain an average cathode power similar to conventional sputtering (1-10 W-cm“2).

[0023] In an embodiment, the titanium coating layer lodged over the second layer deposited in the end of CVD process provides the good adhesion for the AICrN coating deposited through HiPIMS.

[0024] An aspect of the disclosure comprises a tool or wear part comprising a coating over a hard metal substrate, in particular on the surface of the tool or wear part, wherein the coating is a multilayer, a first titanium layer comprising titanium carbonitride, a second layer over the first titanium layer comprising aluminium oxide and a first top layer lodge over the second layer comprising AICrN or AICrN / ZrN deposited though physical vapour deposition. Surprisingly this solution enhances the performance, hardness, durability and overall lifespan of the tool or wear part of the present disclosure and unexpectedly decrease the cracks or microcracks between the coating layers of the tool or wear part of the present disclosure.

[0025] An aspect of the present disclosure relates to a tool or wear part comprising a multilayer coating over a hardmetal substrate, in particular on the surface of the tool or wear part, wherein the multilayer coating comprises: a first titanium layer of TiCxNy comprising titanium carbonitride, wherein x+y=l; a second layer over the first titanium layer comprising aluminium oxide; a first top layer lodge over the second layer comprising AICrN or AICrN / ZrN deposited through physical vapour deposition; wherein the first and the second layer are obtained by chemical vapor deposition; wherein the roughness of the top layer is less of 250 nm. The mentioned roughness was measured using optical 3D metrology.

[0026] The multilayer coating of the present disclosure unexpectedly increases the lifetime of the tool by at least 20%. This surprising enhancement in durability is achieved through the specific combination and deposition methods of the coating layers, which together produce synergistic effects.

[0027] In an embodiment, the hardmetal substrate is tungsten carbide, wherein the tungsten carbide comprises 5-15 %(w / w) of a metallic binder, wherein said metallic binder is selected from: cobalt, nickel and their combinations.

[0028] In an embodiment for better results, the thickness of the top layer of the tool or wear part is from 1 to 4 pm, preferably from 1 to 3 pm for improve the performance, more preferably from 2 to 3 pm for improve the performance.

[0029] In an embodiment for better results, the tool or wear part further comprises a titanium coating layer lodged over the second layer.

[0030] In an embodiment for better results, the titanium coating layer of the tool or wear part comprises titanium nitride.

[0031] In an embodiment for better results, wherein the thickness of the top layer is from 1 to 4 pm, preferably from 1 to 3 pm, more preferably from 2 to 3 pm for improve the performance.

[0032] In an embodiment for better results, wherein the first and the second layer are obtained by chemical vapor deposition.

[0033] In an embodiment for better results, the thickness of the second layer of the tool or wear part is from 1 to 4 pm, preferably from 1.5 to 3.5 pm for improve the performance, more preferably from 1.5 to 3 pm for improve the performance.

[0034] In an embodiment for better results, the elements contained in the AICrN first top layer of the tool or wear part are: aluminium with 30-40 at.%, chromium 20-40 at.% and nitrogen 20 to 40 at.%.

[0035] In an embodiment for better results, the roughness of the top layer is less of around 250 nm, preferably less of around 200 nm; more preferably less of 150 nm.

[0036] In an embodiment for better results, the roughness of the top layer of the tool or wear part is from 100 to 300 nm, preferably from 100 to 200 nm for improve the performance, more preferably from 100 to 150 nm for improve the performance. The roughness can be carried out in a number of ways, in this disclosure the surface coating roughness was evaluated with 3D optical profilometry using the internationalstandard ISO 25178-2:2021 - geometrical product specifications - surface texture: Areal.

[0037] In an embodiment for better results, the tool or wear part further comprises a second top layer lodged over the first top layer, preferably wherein the second top layer comprises ZrN.

[0038] In an embodiment for better results, the aluminium oxide used in the tool or wear part is an alpha-phase AI2O3.

[0039] In an embodiment for better results, the hard metal substrate of the tool or wear part comprises a tungsten carbide-cobalt substrate.

[0040] In an embodiment for better results, the thickness of the titanium coating layer lodged is from 0.5 to 2 pm; preferably from 1 to 1.5 pm.

[0041] In an embodiment for better results, the thickness of the first top layer is from 1 to 4 pm; preferably from 2 to 3 pm.

[0042] In an embodiment for better results, the thickness of the second top layer is from 0.3 to 1 pm; preferably from 0.5 to 0.8 pm.

[0043] In an embodiment for better results, the second layer of the tool or wear part comprises a texture.

[0044] In an embodiment for better results, the tool or wear part of the present disclosure comprises a multilayer coating over a hard metal substrate, in particular on the surface of the tool or wear part, wherein the multilayer coating comprises in this sequence: the first titanium layer comprising titanium carbonitride; the second layer over the first titanium layer comprising aluminium oxide; the titanium coating layer lodged between the second layer and the top layer as an interface layer; the first top layer lodge over the second layer comprising AICrN or AICrN / ZrN deposited though physical vapour deposition; and optionally the second top layer lodged over the first top layer.This solution enhances the surprisingly the performance, hardness, durability and overall lifespan of the tool.

[0045] Another aspect of the disclosure relates to a method for the production a multilayer coating over on a hardmetal substrate of a tool or wear part of the present disclosure, comprising the following steps: pre-treating the substrate of the tool or wear part to prepare the substrate for layer deposition; depositing a first titanium layer comprising titanium carbonitride on the pretreated substrate using chemical vapor deposition; depositing a second layer comprising aluminium oxide on the tool or wear part obtained from the previous step, using chemical vapor deposition; optionally, depositing a titanium coating layer over the second layer on the tool or wear part obtained from the previous step, using chemical vapor deposition; depositing a top layer comprising AICrN or or AICrN / ZrN on the tool or wear part obtained from the preceding step, using physical vapor deposition.

[0046] In an embodiment, further comprising the step of subjecting the tool or wear part obtained to deposition conditions suitable for applying a second top layer comprising ZrN.

[0047] In an embodiment, wherein the physical vapor deposition conditions are selected based on the target compositions and utilize high-power impulse magnetron sputtering ( Hi PI MS), for better results.

[0048] Along this text, it is considered that High Power Impulse Magnetron Sputtering (HIPI MS) is a sputtering technology that builds upon the advantages of conventional magnetron sputtering. In magnetron sputtering, increased plasma densities are created near the target that boost the sputtering rate beyond that of traditional diode technology.

[0049] Along this text, it is considered that the atomic percent, or at. %, gives the percentage of one kind of atom relative to the total number of atoms. The molecular equivalent of this concept is the molar percent.BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The following figures provide preferred embodiments for illustrating the disclosure and should not be seen as limiting the scope of invention.

[0051] Figure 1: Photographic representation of an embodiment of a coating of a tool or wear part with the total multilayer coating thickness of 9 to 13 pm (CVD+HiPIMS).

[0052] Figure 2: Photographic representation of an embodiment of a coating of a tool or wear part with multilayer coating CVD (7-10 pm) and HiPIMS (2-3 pm) measurements.

[0053] Figure 3: Photographic representation of an embodiment of a coating of a tool or wear part with TiN / TiCN (4-6 pm), AI2O3 (2-3 pm) and TiN (0.3-1.0 pm).

[0054] Figure 4: Photographic representation of a microstructure of an embodiment of the multilayer coating of a tool or wear part with TiN / TiCN (4-6 pm), AI2O3 (2-3 pm), TiN (0.3-1.0 pm) and AICrN (2-3 pm) and respective chemical map composition (Ti for TiN and TiCN; Al for AI2O3 and Cr for AICrN).

[0055] Figure 5: Photographic representation of a microstructure of an embodiment of the multilayer coating of a tool or wear part with TiN / TiCN (4-6 pm), AI2O3 (2-3 pm), TiN (0.3-1.0 pm), AICrN (2-3 pm) and ZrN (0.3-1.0 pm).

[0056] Figure 6: Schematic presentation of an embodiment of tool or wear part comprising a multilayer coating over a hard metal substrate of the present disclosure.

[0057] Throughout the figures indicated above, the following elements are indicated with the respective references:1 - hard metal substrate;2 - first titanium layer;3 - second layer;4 - interface of the second layer with the first top layer;5 - first top layer.DETAILED DESCRIPTION

[0058] The present disclosure relates to a tool or wear part and coating method to deposit a coating on a tool or wear part.

[0059] It is disclosed a tool or wear part comprising a coating over a hard metal substrate, in particular on the surface of the tool or wear part, wherein the coating is a multilayer, a first titanium layer comprising titanium carbonitride, a second layer comprising aluminium oxide; and a first top layer lodged over the second layer comprising AICrN or AICrN / ZrN deposited though physical vapour deposition.

[0060] The first TiN layer provides the adhesion between the hard metal substrate and the coating, the fine grain TiCN coating with columnar structure provides hardness and wear resistance against abrasive wear. The high-strength textured alumina coating is chemical inertness and very hard. The second TiN coating layer allows adhesion of the first top layer deposited by HIPIMS. The AICrN coating possess high thermal shock resistance and corrosion resistance. All these characteristics and technical features allow a low degree of coating degradation and permit to avoid the failure of the tool, even considering complex geometric features.

[0061] In an embodiment, the thickness of the top layer of the tool or wear part is from 1 to 4 pm, preferably from 1 to 3 pm, more preferably from 2 to 3 pm, for better results in what concerns the abrasion resistance of said top layer.

[0062] In an embodiment, the tool or wear part further comprises a titanium coating layer lodged over the second layer, for better results in what concerns the adhesion for the AICrN or AICrN / ZrN coating deposited through HiPIMS.

[0063] In an embodiment, the titanium coating layer of the tool or wear part comprises titanium nitride for improving performance of the tool or wear part in machining heat-resistant alloys.

[0064] In an embodiment, the thickness of the titanium coating layer of the tool or wear part is from 0.3 to 2 pm, preferably from 0.3 to 1.5 pm, more preferably from 0.3 to 1 pm, for better results in what concerns the abrasion resistance of said titanium coating layer.

[0065] In an embodiment, the thickness of the second layer of the tool or wear part is from 1 to 4 pm, preferably from 1.5 to 3.5 pm, more preferably from 1.5 to 3 pm, for better results in what concerns the abrasion resistance of said second layer.

[0066] In an embodiment, the elements contained in the AICrN first top layer of the tool or wear part are: aluminium with 30-40 at.%, chromium 20-40 at.% and nitrogen 20 to 40 at.%, for better results.

[0067] In an embodiment, the average roughness of the top layer of the tool or wear part is from 100 to 300 nm, preferably from 100 to 200 nm, more preferably from 100 to 150 nm, for better abrasion capability.

[0068] In an embodiment, the tool or wear part further comprises a second top layer lodged over the first top layer, preferably wherein the second top layer comprises ZrN, for better results.

[0069] In an embodiment, the aluminium oxide used in the tool or wear part is an alpha-phase AI2O3, for better results.

[0070] In an embodiment, the hard metal substrate of the tool or wear part comprises a tungsten carbide-cobalt substrate, for better results.

[0071] In an embodiment, the second layer of the tool or wear part comprises a texture, for better results.

[0072] In figure 1, it is represented a photographic representation of an embodiment of a tool or wear part with the total multilayer coating thickness of 9 to 13 pm (CVD+HiPIMS).

[0073] In figure 2, it is represented a photographic representation of an embodiment of a tool or wear part with multilayer coating CVD (7-10 pm) and HiPIMS (2-3 pm) measurements.

[0074] In figure 3, it is represented a photographic representation of an embodiment of a coating of a tool or wear part with TiN / TiCN (4-6 pm), AI2O3 (2-3 pm), TiN (0.3-1.0 pm) and AICrN (2-3 pm).

[0075] In figure 4, it is represented a microstructure of a multilayer coating of a tool or wear part with TiN / TiCN (4-6 pm), AI2O3 (2-3 pm), TiN (0.3-1.0 pm) and AICrN (2-3 pm)and respective chemical map composition (Ti for TiN and TiCN; Al for AI2O3 and Cr for AICrN).

[0076] In figure 5, it is represented a photographic representation of a microstructure of an embodiment of the multilayer coating of a tool or wear part with TiN / TiCN (4-6 pm), AI2O3 (2-3 pm), TiN (0.3-1.0 pm), AICrN (2-3 pm) and ZrN (0.3-1.0 pm).

[0077] In order to evaluate the performance of the developed coating, a machining test in AISI316 stainless steel with the conditions of cutting speed 200 m / min, feed 0.25 mm / rev and depth of cut 2 mm was performed.Example 1

[0078] Tool coated with AICrN, obtained by a CVD and PVD process on a substrate of WC and Co. The thickness of the first and second layers is 7.5 pm and the top layer of AICrN of 2.2 pm. On such conditions, there is a roughness of 0.15 pm and a durability under the test conditions of 40 min.Example 2

[0079] Tool coated with AICrN / ZrN, obtained by a PVD process on a substrate of WC and Co. The thickness of the first and second layers is 7.5 pm and the top layer of AICrN / ZrN of 1.3 pm. On such conditions, there is a roughness of 0.13 pm and a durability under the test conditions of 40 min.Example 3 (comparative example)

[0080] Tool coated according to the prior art, obtained by a CVD process on a substrate of WC and Co. The thickness of the first and second layer is 7.5 pm. On such conditions, there is a roughness of 0.23 pm and a durability under the test conditions of 30 min.As indicated in table 1, the tool or wear part comprising a coating according to the present disclosure exhibits a significantly enhanced durability and reduced surface roughness.Table 1 - Characterization of the tool* Tungsten carbide-cobalt

[0081] The coating of the present disclosure surprisingly increases the lifetime of the tool in at least 20%.

[0082] In an embodiment, the coating parameters are indicated in Table 2.Table 2 - Coating parameters

[0083] The term "comprising" whenever used in this document is intended to indicate the presence of stated features, integers, steps, components, but not to preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0084] The disclosure should not be seen in any way restricted to the embodiments described and a person with ordinary skill in the art will foresee many possibilities to modifications thereof. The above-described embodiments are combinable.

[0085] The following dependent claims further set out particular embodiments of the disclosure.

Claims

C L A I M S1. A tool or wear part comprising a multilayer coating over a hardmetal substrate, in particular on the surface of the tool or wear part, wherein the multilayer coating comprises: a first titanium layer of TiCxNy comprising titanium carbonitride, wherein x+y=l; a second layer over the first titanium layer comprising aluminium oxide; a first top layer lodge over the second layer comprising AICrN or AICrN / ZrN deposited through physical vapour deposition; wherein the first and the second layer are obtained by chemical vapor deposition; wherein the roughness of the top layer is less of 250 nm.

2. The tool or wear part according to the previous claim, wherein the hardmetal substrate is tungsten carbide, wherein the tungsten carbide comprises 5-15 %(w / w) of a metallic binder, wherein said metallic binder is selected from: cobalt, nickel and their combinations.

3. The tool or wear part according to any of the previous claims, wherein the thickness of the first top layer is from 1 to 4 pm.

4. The tool or wear part according to the previous claim, wherein the thickness of the first top layer ranges from 1 to 3 pm, preferably from 2 to 3 pm.

5. The tool or wear part according to any of the previous claims, wherein the thickness of the first titanium layer is from 1 to 6 pm.

6. The tool or wear part according to the previous claim, wherein the thickness of the first titanium layer ranges from 1.5 to 4 pm; preferably from 2 to 3 pm.

7. The tool or wear part according to any of the previous claims, wherein the thickness of the second layer is from 1 to 4 pm.

8. The tool or wear part according to the previous claim, wherein the thickness of the second layer ranges from 1.5 to 3.5 pm; preferably from 2 to 3 pm.

9. The tool or wear part according to any of the previous claims, further comprising a titanium coating layer lodged over the second layer, preferably wherein the titanium coating layer comprises titanium nitride.

10. The tool or wear part according to any of the previous claims, wherein the elements contained in the AICrN first top layer are: aluminium with 30-40 at.%, chromium 20-40 at.% and nitrogen 20 to 40 at.%.

11. The tool or wear part according to any of the previous claims, wherein the roughness of the top layer is less of 200 nm; preferably less of 150 nm.

12. The tool or wear part according to any of the previous claims, further comprising a second top layer lodged over the first top layer.

13. The tool or wear part according to the previous claim, wherein the second top layer comprises ZrN.

14. The tool or wear part according to any of the previous claims, wherein the aluminium oxide is an alpha-phase AI2O3.

15. The tool or wear part according to any of the previous claims, wherein the hard metal substrate comprises a tungsten carbide-cobalt substrate.

16. The tool or wear part according to any of the previous claims, wherein the second layer comprises a texture.

17. Method for the production a multilayer coating over on a hardmetal substrate of a tool or wear part described in any of the previous claims, comprising the following steps:pre-treating the substrate of the tool or wear part to prepare the substrate for layer deposition; depositing a first titanium layer comprising titanium carbonitride on the pretreated substrate using chemical vapor deposition; depositing a second layer comprising aluminium oxide on the tool or wear part obtained from the previous step, using chemical vapor deposition; optionally, depositing a titanium coating layer over the second layer on the tool or wear part obtained from the previous step, using chemical vapor deposition; depositing a top layer comprising AICrN or or AICrN / ZrN on the tool or wear part obtained from the preceding step, using physical vapor deposition.

18. The method according to the preceding claim, further comprising the step of subjecting the tool or wear part obtained to deposition conditions suitable for applying a second top layer comprising ZrN.

19. The method according to any of the claims 17 to 18, wherein the physical vapor deposition conditions are selected based on the target compositions and utilize high-power impulse magnetron sputtering (Hi PI MS).

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