Composite wear resistant coating on wc-12co cemented carbide and method of making same

Abstract

The application discloses a kind of composite wear-resistant coating on WC-12Co hard alloy and preparation method thereof, the method comprises: WC-12Co hard alloy substrate is sequentially carried out spray cleaning, ultrasonic cleaning, rinsing and drying pretreatment;After pretreatment, substrate is placed into multi-arc ion plating device, vacuum is extracted after heating, and ion activation cleaning is carried out;At the deposition temperature of 390-410 ℃, using multi-arc ion plating process, Ti bonding layer, TiN transition layer, AlTiN functional bearing layer and CrN top layer are sequentially deposited on the surface of the activated cleaning substrate, to form the multilayer composite wear-resistant coating sequentially stacked by Ti layer, TiN layer, AlTiN layer and CrN layer.The application realizes the synergistic promotion of film base bonding force, interlayer stress matching, main body bearing capacity and surface anti-sticking / anti-peeling performance.

Description

Technical Field

[0001] This invention belongs to the field of cemented carbide surface engineering and physical vapor deposition coating technology, and in particular relates to a composite wear-resistant coating on WC-12Co cemented carbide and its preparation method. Background Technology

[0002] WC-Co cemented carbide is widely used in cutting tools and critical wear-resistant components due to its excellent comprehensive mechanical properties. However, under high-load, highly interactive tribological conditions such as titanium alloy cutting, its surface is prone to abrasive wear, adhesion transfer, and fatigue spalling, leading to a decrease in tool life and machining stability. Especially when cutting active titanium alloys such as TC4, intense material adhesion and cyclic shearing can easily cause coating surface damage and premature failure. In addition, in multi-medium environments such as atmosphere, water, or cutting fluid, the penetration of the medium into coating defects or interfaces can accelerate the erosion and spalling process, causing premature exposure of the substrate. To improve the surface properties of cemented carbide, physical vapor deposition technology, especially AlTiN-based hard coatings, has become an important strengthening method. However, due to the difference in physical properties between a single-layer AlTiN coating and the substrate, interfacial stress concentration is prone to occur, which may lead to interfacial cracking and local delamination under alternating loads and cutting thermal coupling. Therefore, the industry usually adopts a multi-layer design that introduces bonding layers and transition layers to improve film-substrate bonding and alleviate internal stress. Meanwhile, applying a protective layer with low adhesion tendency and high chemical stability to the surface is also considered an effective way to improve the reliability of the coating under complex working conditions.

[0003] Current research has explored the synergistic improvement of coating hardness, thermal stability, and wear resistance through multilayer systems comprising transition layers and multi-component composite nitride surfaces. However, these designs typically involve composite nitrides formed by the co-deposition of multiple metallic elements, with performance tuning focusing on overall solid solution strengthening and high-temperature performance optimization. Facing the unique challenges of adhesion and shearing in titanium alloy machining, as well as progressive interfacial failure under complex frictional environments, existing coating systems still have room for improvement in the synergistic design of interfacial bonding toughness, interlayer stress matching, and surface anti-adhesion properties.

[0004] Therefore, for specific failure modes of WC-12Co cemented carbide in titanium alloy cutting and multi-media friction environments, how to achieve simultaneous strong and tough bonding, stress relief, main body load bearing and surface protection through innovative material system design and refined structural design of coatings, especially systematic optimization of the thickness, performance and deposition process of each independent functional layer, has become a key research direction for improving the service performance and stability of cutting tools. Summary of the Invention

[0005] The purpose of this invention is to provide a composite wear-resistant coating on WC-12Co cemented carbide and its preparation method, which solves the problems of insufficient anti-adhesion performance, easy peeling at the interface, and poor service stability of the coating in the prior art under titanium alloy cutting and multi-media friction conditions. It achieves a synergistic improvement in film-substrate adhesion, interlayer stress matching, main body load-bearing capacity and surface anti-adhesion / anti-peeling performance.

[0006] The technical solution adopted in this invention is a method for preparing a composite wear-resistant coating on WC-12Co cemented carbide, comprising the following steps:

[0007] Step S1: The WC-12Co cemented carbide substrate is subjected to spray cleaning, ultrasonic cleaning, rinsing and drying pretreatment in sequence;

[0008] Step S2: Place the pretreated substrate into a multi-arc ion plating apparatus, evacuate the vacuum, heat up, and perform ion activation cleaning.

[0009] Step S3: At a deposition temperature of 390–410 °C, a multi-arc ion plating process is used to sequentially deposit a Ti bonding layer, a TiN transition layer, an AlTiN functional bearing layer, and a CrN top layer on the activated and cleaned substrate surface, thereby forming a multi-layer composite wear-resistant coating.

[0010] Further, in step S1, the temperature of the spray cleaning is 55-65 ℃ and the time is 270-330 s; the temperature of the ultrasonic cleaning is 55-65 ℃ and the time is 570-630 s; the temperature of the rinsing is 45-55 ℃ and the time is 270-330 s; and the temperature of the drying is 110-130 ℃ and the time is 870-930 s.

[0011] Furthermore, in step S2, when the device's base vacuum reaches 5.0 × 10⁻⁶... -2 After Pa, the temperature is raised to 390–410 °C and held; argon and hydrogen are introduced for ion activation cleaning for 115–125 min; hydrogen is used only in the ion activation cleaning stage and does not participate in subsequent coating deposition.

[0012] Furthermore, in step S3,

[0013] When depositing the Ti bonding layer, a pure Ti target is used, and deposition is carried out in a pure Ar atmosphere with a substrate bias voltage of 85–95 V and a working pressure of 1.2–1.4 Pa.

[0014] When depositing the TiN transition layer, a pure Ti target was used, and the deposition was carried out in an Ar and N2 reaction atmosphere. The substrate bias voltage was 85–95 V, and the working pressure was 0.7–0.9 Pa.

[0015] When depositing the AlTiN functional carrier layer, a TiAl target is used, and the deposition is carried out in an Ar and N2 reaction atmosphere. The substrate bias voltage is 65-75 V, and the working pressure is 3.3-3.7 Pa.

[0016] When depositing the CrN top layer, a pure Cr target is used, and the deposition is carried out in an Ar and N2 reaction atmosphere. The substrate bias voltage is 125–135 V, and the working pressure is 0.9–1.1 Pa.

[0017] Furthermore, in the TiAl target material, the atomic ratio of Ti to Al is 33:67.

[0018] Furthermore, the total deposition time of the coating is 8550–8650 s; during the deposition process, Ar is introduced throughout at a flow rate of 345–355 sccm; N2 is introduced only during the deposition stages of the TiN transition layer, the AlTiN functional carrier layer, and the CrN top layer at a flow rate of 845–855 sccm; the substrate bias is applied using a DC pulse method with a pulse frequency of 30 kHz, a duty cycle of 60%–90%, an arc current of 120 A, and a workpiece rotating frame rotation speed of 1.8–2.2 r / min.

[0019] The present invention also provides a composite wear-resistant coating on WC-12Co cemented carbide, which is prepared by the method described in any of the preceding claims, wherein the total thickness of the multilayer composite wear-resistant coating is 2.93 to 3.40 μm;

[0020] The thickness of the Ti bonding layer is 0.03–0.05 μm, the thickness of the TiN transition layer is 0.18–0.25 μm, the thickness of the AlTiN functional bearing layer is 2.4–2.7 μm, and the thickness of the CrN top layer is 0.32–0.40 μm.

[0021] The beneficial effects of this invention are:

[0022] 1. This invention constructs a gradient composite structure consisting of a Ti bonding layer / TiN transition layer / AlTiN functional load-bearing layer / independent CrN thin top layer, and synergistically optimizes the thickness of each layer and the deposition process. This achieves multifunctional integration of film-substrate bonding enhancement, interlayer stress relief, main body load-bearing support and surface anti-adhesion protection, thereby significantly improving the overall performance and service reliability of the coating system.

[0023] 2. In the coating provided by the present invention, the independently deposited CrN thin top layer has better chemical stability and lower adhesion tendency, which can effectively block the adhesion and transfer of titanium alloy materials, while helping to improve the surface integrity and anti-stripping ability of the coating, thus suppressing the failure origin from the surface protection level.

[0024] 3. This invention enables the coating to delay key failure processes such as interface cracking, progressive peeling of the coating, and premature exposure of the substrate under the cutting and atmospheric friction and wear conditions of TC4 titanium alloy, thereby improving the service life and machining stability of WC-12Co cemented carbide tools and wear-resistant parts.

[0025] 4. The preparation method adopted in this invention is based on a mature multi-arc ion plating process. The key parameters are clear, the process has good repeatability, and it is easy to implement on existing industrial equipment, thus having good prospects for engineering applications. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the composite wear-resistant coating of the present invention.

[0028] Figure 2 The images show the surface morphology and elemental distribution of the AlTiN / CrN coating prepared in Comparative Example 3. (a) is a SEM image of the surface morphology, and (b) is an EDS image of the surface distribution of Ti, Al, N, O, C, and Cr elements.

[0029] Figure 3 The images show the surface morphology and elemental distribution of the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1. (a) is a SEM image of the surface morphology, and (b) is an EDS image of the surface distribution of Ti, Al, N, O, C, and Cr elements.

[0030] Figure 4 The images show cross-sectional TEM images of the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1, where (a) is a cross-sectional TEM morphology image and (b) is an EDS elemental distribution map of the corresponding region.

[0031] Figure 5 The images show cross-sectional TEM images of the TiN coating in the multilayer composite coating prepared in Example 1, where (a) is a low-magnification cross-sectional morphology image at a scale of 50 nm, (b) is a high-magnification transmission morphology image at a scale of 5 nm, and (c) is the corresponding selected area electron diffraction pattern.

[0032] Figure 6The images shown are cross-sectional TEM images of the AlTiN coating in the multilayer composite coating prepared in Example 1. (a) is a low-magnification cross-sectional morphology image at a scale of 50 nm, (b) is a high-magnification transmission morphology image at a scale of 5 nm, and (c) is the corresponding selected area electron diffraction pattern.

[0033] Figure 7 The images shown are TEM images of the cross-section of the CrN coating in the multilayer composite coating prepared in Example 1. (a) is a low-magnification cross-sectional morphology image at a scale of 50 nm, (b) is a high-magnification transmission morphology image at a scale of 5 nm, and (c) is the corresponding selected area electron diffraction pattern.

[0034] Figure 8 The images show a comparison of the three-dimensional surface morphology and roughness of the AlTiN / CrN prepared in Comparative Example 3 and the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1. In the images, (a) is the AlTiN / CrN coating and (b) is the Ti / TiN / AlTiN / CrN multilayer coating.

[0035] Figure 9 The image shows a comparison of the nanoindentation mechanical properties of the AlTiN / CrN coating prepared in Comparative Example 3 and the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1. (a) represents hardness and elastic modulus, and (b) represents H / E and H... 3 / E 2 ratio.

[0036] Figure 10 The scratch adhesion curves and scratch morphology diagrams of the AlTiN / CrN coating prepared in Comparative Example 3 and the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1 are shown. (a) is the AlTiN / CrN coating, and (b) is the Ti / TiN / AlTiN / CrN multilayer composite coating.

[0037] Figure 11 To compare the friction and wear results of the AlTiN / CrN coating prepared in Comparative Example 3 and the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1 under different loads, (a), (b), and (c) are the friction coefficient curves under loads of 6 N, 8 N, and 10 N, respectively, and (d) is the wear rate bar chart under different loads.

[0038] Figure 12 The image shows the evolution of the rake face wear morphology and elemental distribution of the AlTiN / CrN composite coated tool prepared in Comparative Example 3 during the cutting process of TC4 titanium alloy. In the image, (a), (c), (e), (g), and (i) are the wear results at stages T1, T3, T5, T7, and T9, respectively; and (b), (d), (f), (h), and (j) are the elemental distribution diagrams for the corresponding stages.

[0039] Figure 13 The image shows the evolution of the rake face wear morphology and elemental distribution of the Ti / TiN / AlTiN / CrN multilayer composite coated tool prepared in Example 1 during the cutting process of TC4 titanium alloy. Among them, (a), (c), (e), (g), and (i) are the wear results at stages T1, T3, T5, T7, and T9, respectively; (b), (d), (f), (h), and (j) are the elemental distribution diagrams at the corresponding stages. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Example 1:

[0042] The preparation method of composite wear-resistant coating on WC-12Co cemented carbide, such as Figure 1 As shown, it includes the following steps:

[0043] Step S1: Pretreatment of the WC-12Co cemented carbide substrate; first, spray cleaning with a water-based cleaning solution at 60℃ for 300 s to remove surface deposits; then, ultrasonic cleaning with the cleaning solution at 60℃ for 600 s, with an ultrasonic frequency of 40 kHz and a power density of 0.3–0.6 W / cm³. 2 The substrate is first rinsed with 50°C deionized water for 300 seconds to remove cleaning agent residue; then, it is dried at 120°C for 900 seconds to completely remove moisture; the dried substrate is placed in a desiccator to cool to room temperature and transferred to the coating chamber as soon as possible to reduce secondary contamination.

[0044] Step S2: Place the pretreated WC-12Co cemented carbide substrate into a multi-arc ion plating apparatus and evacuate to a base vacuum level of 5.0 × 10⁻⁶. -2 Pa, then heated to 400 ℃ and held at that temperature; during the ion activation cleaning stage, argon and hydrogen were introduced, and ion etching cleaning was performed for 120 min under DC pulse bias; argon ions generated by argon ionization continuously bombarded the substrate surface under pulse bias acceleration to perform argon ion etching, in order to remove surface adsorbates and weakened layers and generate activated rough surfaces; hydrogen was used to reduce the slight oxide layer on the substrate metal surface after ionization during the etching stage, and worked with argon ions to complete surface activation, thereby improving the bonding stability between the subsequent coating and the substrate;

[0045] Step S3: On the activated and cleaned substrate, a Ti bonding layer, a TiN transition layer, an AlTiN functional support layer, and a CrN top layer are sequentially deposited using a multi-arc ion plating process at a deposition temperature of 400℃. Specifically, the Ti bonding layer is deposited using a pure Ti target in a pure Ar atmosphere with a bias voltage of 90 V and an operating pressure of 1.3 Pa; the TiN transition layer is deposited using a pure Ti target in an Ar and N2 reaction atmosphere with a bias voltage of 90 V and an operating pressure of 0.8 Pa; the AlTiN functional support layer is deposited using a TiAl target in an Ar and N2 reaction atmosphere with a bias voltage of 70 V and an operating pressure of 3.5 Pa; the atomic ratio of Ti to Al in the TiAl target is 33:67; and the CrN top layer is deposited using a pure Cr target in an Ar and N2 reaction atmosphere with a bias voltage of 130 V and an operating pressure of 1.0 Pa. During the deposition process, Ar was used as the working gas to maintain the multi-arc ion plating discharge and deposition environment, and was introduced at a constant flow rate of 350 sccm throughout the process. N2 was introduced as the reactive gas only in the TiN transition layer, AlTiN functional carrier layer and CrN top layer deposition stages, with a flow rate of 850 sccm. H2 was only used in the ion activation cleaning stage and did not participate in subsequent coating deposition. In each deposition stage, the working pressure was maintained within the target range by adjusting the exhaust flow of the cavity under the required atmosphere. The substrate bias was adopted in the form of DC pulse, with a pulse frequency of 30 kHz, a duty cycle of 75%, an arc current of 120 A, and a workpiece rotation speed of 2 r / min. During the conversion between each deposition layer, the parameters of the target material, gas, pressure and bias were adjusted step by step to achieve a smooth transition of process parameters. The next layer was deposited only after the parameters stabilized. This process was uninterrupted between layers to form a continuous transition of composition and structure at the interface. The total deposition time was 8600 s, and a Ti / TiN / AlTiN / CrN multilayer composite wear-resistant coating was finally obtained.

[0046] In the coating prepared in Example 1, the thicknesses of each layer are as follows: Ti bonding layer is 0.039 μm, TiN transition layer is 0.215 μm, AlTiN functional carrier layer is 2.56 μm, and CrN top layer is 0.365 μm; the total coating thickness is 3.18 μm, wherein the thickness ratio of CrN top layer to AlTiN functional carrier layer is 1:7.0.

[0047] Example 2:

[0048] The method for preparing a composite wear-resistant coating on WC-12Co cemented carbide includes the following steps:

[0049] Step S1: Pretreatment of the WC-12Co cemented carbide substrate; first, spray cleaning with a water-based cleaning solution at 55 ℃ for 270 s to remove surface deposits; then, ultrasonic cleaning with the cleaning solution at 55 ℃ for 570 s, with an ultrasonic frequency of 40 kHz and a power density of 0.3~0.6 W / cm³. 2 The substrate is first rinsed with deionized water at 45°C for 270 seconds to remove grease and fine particles; then rinsed with deionized water at 45°C for 270 seconds to remove cleaning agent residue; finally, it is dried at 110°C for 870 seconds to remove moisture; the dried substrate is placed in a desiccator to cool to room temperature and transferred to the coating chamber as soon as possible to reduce secondary contamination.

[0050] Step S2: Place the pretreated WC-12Co cemented carbide substrate into a multi-arc ion plating apparatus and evacuate to a base vacuum level of 5.0 × 10⁻⁶. -2 Pa, then heated to 390 ℃ and held at that temperature; during the ion activation cleaning stage, argon and hydrogen were introduced, and ion etching cleaning was performed for 115 min under DC pulse bias; argon ions generated by argon ionization continuously bombarded the substrate surface under pulse bias acceleration to perform argon ion etching, in order to remove surface adsorbates and weakened layers and generate activated rough surfaces; hydrogen was used to reduce the slight oxide layer on the substrate metal surface after ionization during the etching stage, and worked with argon ions to complete surface activation, thereby improving the bonding stability between the subsequent coating and the substrate;

[0051] Step S3: On the activated and cleaned substrate, a Ti bonding layer, a TiN transition layer, an AlTiN functional support layer, and a CrN top layer are sequentially deposited using a multi-arc ion plating process at a deposition temperature of 390 °C. Specifically, the Ti bonding layer is deposited using a pure Ti target in a pure Ar atmosphere with a bias voltage of 85 V and an operating pressure of 1.2 Pa; the TiN transition layer is deposited using a pure Ti target in an Ar and N2 reaction atmosphere with a bias voltage of 85 V and an operating pressure of 0.7 Pa; the AlTiN functional support layer is deposited using a TiAl target in an Ar and N2 reaction atmosphere with a bias voltage of 65 V and an operating pressure of 3.3 Pa; the atomic ratio of Ti to Al in the TiAl target is 33:67; and the CrN top layer is deposited using a pure Cr target in an Ar and N2 reaction atmosphere with a bias voltage of 125 V and an operating pressure of 0.9 Pa. During the deposition process, Ar was used as the working gas to maintain the multi-arc ion plating discharge and deposition environment, and was introduced at a constant flow rate of 345 sccm throughout the process. N2 was introduced as the reactive gas only in the TiN transition layer, AlTiN functional carrier layer and CrN top layer deposition stages, with a flow rate of 845 sccm. H2 was only used in the ion activation cleaning stage and did not participate in subsequent coating deposition. In each deposition stage, the working pressure was maintained within the target range by adjusting the exhaust flow of the cavity under the required atmosphere. The substrate bias was adopted in the form of DC pulse, with a pulse frequency of 30 kHz, a duty cycle of 60%, an arc current of 120 A, and a workpiece rotation speed of 1.8 r / min. When switching between layers, the target material, gas, pressure and bias were adjusted according to the process requirements of the next layer. The next layer was deposited only after the parameters stabilized, and the layers were not interrupted to ensure the continuity of the interface. The total deposition time was 8550 s, and a Ti / TiN / AlTiN / CrN multilayer composite wear-resistant coating was finally obtained.

[0052] In the coating prepared in Example 2, the thicknesses of each layer are as follows: Ti bonding layer is 0.033 μm, TiN transition layer is 0.190 μm, AlTiN functional support layer is 2.42 μm, and CrN top layer is 0.330 μm; the total coating thickness is 2.973 μm, wherein the thickness ratio of the CrN top layer to the AlTiN functional support layer is approximately 1:7.3. This thickness distribution is within the range defined by this invention and can form a multilayer composite structure in which the Ti bonding layer, TiN transition layer, AlTiN functional support layer, and CrN top layer are stacked sequentially. The coating prepared in Example 2 has a hardness of 33.12 GPa, an elastic modulus of 359.20 GPa, an H / E ratio of 0.092, and a H... 3 / E 2 The value of 0.281 GPa indicates that the coating can maintain high hardness, strong load-bearing capacity and good resistance to plastic deformation even under low process parameters, which can meet the wear resistance and strengthening requirements of WC-12Co cemented carbide surface.

[0053] Example 3:

[0054] The method for preparing a composite wear-resistant coating on WC-12Co cemented carbide includes the following steps:

[0055] Step S1: Pretreatment of the WC-12Co cemented carbide substrate; first, spray cleaning with a water-based cleaning solution at 65 ℃ for 330 s to remove surface deposits; then, ultrasonic cleaning with the cleaning solution at 65 ℃ for 630 s, with an ultrasonic frequency of 40 kHz and a power density of 0.3~0.6 W / cm³. 2 The substrate is first rinsed with deionized water at 55°C for 330 seconds to remove grease and fine particles; then rinsed with deionized water at 55°C for 330 seconds to remove cleaning agent residue; finally, it is dried at 130°C for 930 seconds to remove moisture; the dried substrate is placed in a desiccator to cool to room temperature and transferred to the coating chamber as soon as possible to reduce secondary contamination.

[0056] Step S2: Place the pretreated WC-12Co cemented carbide substrate into a multi-arc ion plating apparatus and evacuate to a base vacuum level of 5.0 × 10⁻⁶. -2 Pa, then heated to 410 °C and held at that temperature; during the ion activation cleaning stage, argon and hydrogen were introduced, and ion etching cleaning was performed for 125 min under DC pulse bias; argon ions generated by argon ionization continuously bombarded the substrate surface under pulse bias acceleration to perform argon ion etching, in order to remove surface adsorbates and weakened layers and generate activated rough surfaces; hydrogen was used to reduce the slight oxide layer on the substrate metal surface after ionization during the etching stage, and worked with argon ions to complete surface activation, thereby improving the bonding stability between the subsequent coating and the substrate;

[0057] Step S3: On the activated and cleaned substrate, a Ti bonding layer, a TiN transition layer, an AlTiN functional carrier layer, and a CrN top layer are sequentially deposited using a multi-arc ion plating process at a deposition temperature of 410 °C. Specifically, the Ti bonding layer is deposited using a pure Ti target in a pure Ar atmosphere with a bias voltage of 95 V and an operating pressure of 1.4 Pa; the TiN transition layer is deposited using a pure Ti target in an Ar and N2 reaction atmosphere with a bias voltage of 95 V and an operating pressure of 0.9 Pa; the AlTiN functional carrier layer is deposited using a TiAl target in an Ar and N2 reaction atmosphere with a bias voltage of 75 V and an operating pressure of 3.7 Pa; the atomic ratio of Ti to Al in the TiAl target is 33:67; the CrN top layer is deposited using a pure Cr target in an Ar and N2 reaction atmosphere with a bias voltage of 135 V and an operating pressure of 1.1 Pa. During the deposition process, Ar is used as the working gas to maintain the multi-arc ion plating discharge and deposition environment, and is constantly supplied throughout at a flow rate of 355 Nm³ / h. The nitrogen gas (N2) was introduced only into the TiN transition layer, AlTiN functional carrier layer, and CrN top layer deposition stages at a flow rate of 855 sccm. H2 was used only in the ion activation cleaning stage and did not participate in subsequent coating deposition. During each deposition stage, the working pressure was maintained within the target range by adjusting the exhaust flow of the chamber under the required atmosphere. The substrate bias was applied using a DC pulse method with a pulse frequency of 30 kHz, a duty cycle of 90%, an arc current of 120 A, and a workpiece rotation speed of 2.2 r / min. During the transition between layers, the target material, gas, pressure, and bias were adjusted according to the process requirements of the next layer. The next layer was deposited only after the parameters stabilized, ensuring uninterrupted deposition between layers and maintaining interface continuity. The total deposition time was 8650 s, ultimately yielding a multilayer composite wear-resistant Ti / TiN / AlTiN / CrN coating.

[0058] In the coating prepared in Example 3, the thicknesses of each layer are as follows: Ti bonding layer is 0.047 μm, TiN transition layer is 0.240 μm, AlTiN functional support layer is 2.68 μm, and CrN top layer is 0.390 μm; the total coating thickness is 3.357 μm, wherein the thickness ratio of the CrN top layer to the AlTiN functional support layer is approximately 1:6.9. This thickness distribution is within the range defined by this invention and can form a multilayer composite structure in which the Ti bonding layer, TiN transition layer, AlTiN functional support layer, and CrN top layer are stacked sequentially. The coating prepared in Example 3 has a hardness of 33.94 GPa, an elastic modulus of 364.30 GPa, an H / E ratio of 0.093, and a H... 3 / E 2 The value of 0.295 GPa indicates that the coating can maintain high hardness, strong load-bearing capacity and good resistance to plastic deformation even under high process parameters, which can meet the wear resistance and strengthening requirements of WC-12Co cemented carbide surface.

[0059] Comparative Example 1:

[0060] This comparative example specifically provides a single-layer AlTiN coating prepared on a WC-12Co cemented carbide substrate, used for performance comparison with the multilayer composite coating obtained in Example 1 of this invention, to highlight the necessity of the multilayer composite structure design of this invention; the specific steps are as follows:

[0061] Except for the following adjustments, all other steps and conditions are the same as in Example 1:

[0062] After ion activation cleaning, only the AlTiN functional carrier layer is deposited, without depositing the Ti bonding layer, TiN transition layer, and CrN top layer. The deposition process parameters of the AlTiN layer are consistent with those in Example 1: a TiAl target is used with an atomic ratio of Ti to Al of 33:67. Reactive deposition is carried out under a bias voltage of 70 V and a working pressure of 3.5 Pa. The deposition time corresponds to obtaining a thickness comparable to that of the AlTiN layer in Example 1. Finally, a single AlTiN coating is obtained.

[0063] Comparative Example 2:

[0064] This comparative example specifically provides a Ti / TiN / AlTiN multilayer coating prepared on a WC-12Co cemented carbide substrate, used for comparison with the Ti / TiN / AlTiN / CrN composite coating obtained in Example 1 of this invention, to illustrate the key role of the independent CrN thin top layer in improving surface protection and anti-adhesion performance; the specific steps are as follows:

[0065] Except for the following adjustments, all other steps and conditions are the same as in Example 1:

[0066] After ion activation cleaning, only the Ti bonding layer, TiN transition layer, and AlTiN functional support layer were deposited sequentially, without depositing the CrN top layer. The deposition parameters for each layer were exactly the same as those for the corresponding layers in Example 1, with the total deposition time adjusted accordingly.

[0067] Comparative Example 3:

[0068] This comparative example specifically provides an AlTiN / CrN composite coating prepared on a WC-12Co cemented carbide substrate, used for comparison with the Ti / TiN / AlTiN / CrN multilayer composite coating obtained in Example 1 of this invention, to illustrate the indispensable role of the Ti bonding layer and the TiN transition layer in achieving strong and tough interfacial bonding and alleviating stress concentration; the specific steps are as follows:

[0069] Except for the following adjustments, all other steps and conditions are the same as in Example 1:

[0070] After completing the ion activation cleaning, instead of depositing the Ti bonding layer and the TiN transition layer, the AlTiN functional carrier layer and the CrN top layer are deposited directly on the substrate in sequence. The deposition parameters of the AlTiN layer and the CrN top layer are kept consistent with the corresponding layers in Example 1, and the total deposition time is adjusted accordingly.

[0071] The surface morphology and elemental distribution of the AlTiN / CrN composite coating prepared in Comparative Example 3 and the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1 were characterized. Figure 2 (a)- Figure 2 As shown in (b), the AlTiN / CrN composite coating prepared in Comparative Example 3 can continuously cover the surface of the WC-12Co cemented carbide substrate, and the surface is relatively smooth overall. However, a certain number of arc-shaped particles, micro-pits, and local irregular defects can still be observed, indicating that the coating is still affected by droplet particle deposition and local redeposition during the multi-arc ion plating deposition process. The corresponding elemental distribution results show that Ti, Al, N, and Cr elements are all distributed on the coating surface. Among them, the Cr element signal is relatively continuous, indicating that the CrN top layer has formed a cover on the surface of the AlTiN functional layer. The O and C element signals are relatively weak, mainly related to slight oxidation and adsorption contamination on the coating surface.

[0072] like Figure 3 (a)- Figure 3 As shown in (b), the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1 has a more uniform and dense surface, with a relatively reduced number of granular protrusions and pits, and a lower degree of surface defects than Comparative Example 3. The corresponding elemental distribution results show that Ti, Al, N, and Cr elements are relatively uniformly distributed within the observation area, with no obvious large-area elemental segregation or missing regions, indicating good structural continuity and compositional correspondence between the Ti / TiN transition layer, the AlTiN functional support layer, and the CrN top layer. Compared with Comparative Example 3, the multilayer composite coating obtained in Example 1 has better surface integrity, indicating that the introduction of the Ti bonding layer and the TiN transition layer helps improve the deposition and growth state of the subsequent AlTiN functional support layer and the CrN top layer, thereby improving the surface density and structural stability of the coating.

[0073] The cross-sectional structure of the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1 was systematically characterized. For example... Figure 4 (a)- Figure 4 (b) Figure 5 (a)- Figure 5 (c) Figure 6 (a)- Figure 6 (c) Figure 7 (a)- Figure 7As shown in (c), the cross-sectional characterization results show that the coating consists of a CrN top layer, an AlTiN functional support layer, a TiN transition layer and a Ti bonding layer from the outside to the inside. The interfaces of each layer are clear and continuous, and no obvious through cracks or large-scale defects were observed.

[0074] In the sample of Example 1, the thicknesses of each layer were as follows: CrN layer 0.365 μm, AlTiN layer 2.56 μm, TiN layer 0.215 μm, and Ti bonding layer 0.039 μm. Corresponding elemental distribution analysis showed that Cr was mainly enriched in the outermost surface layer, Ti and Al were concentrated in the middle functional support layer region, and N was continuously distributed in the CrN, AlTiN, and TiN layers, indicating that the coating has a clear layered structure and a good chemical composition correspondence. In the above results, the thickness ratio of the CrN top layer to the AlTiN functional support layer was 1:7. This invention controls the thickness of the CrN top layer within the range of 0.32–0.40 μm to ensure that the CrN layer fully performs its function of surface anti-adhesion and shear protection, while avoiding the risk of residual stress accumulation and interlayer peeling that may be caused by an excessively thick top layer.

[0075] The three-dimensional surface morphology and roughness of the AlTiN / CrN composite coating prepared in Comparative Example 3 and the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1 were tested, and the results are as follows: Figure 8 As shown. By Figure 8 (a) As can be seen, the AlTiN / CrN composite coating prepared in Comparative Example 3 exhibits significant peak-valley undulations on its surface, with protrusions and depressions observed in localized areas, indicating that its surface height distribution is not uniform. These surface undulations are mainly related to arc-spot particle deposition, droplet redeposition, and localized micro-defects during multi-arc ion plating. Higher surface undulations easily lead to localized stress concentrations during frictional contact. Figure 8 As shown in (b), the surface of the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1 is relatively smooth, with a smaller peak-to-valley undulation amplitude and a surface roughness Ra of 0.1263 μm. Compared with Comparative Example 3, the multilayer composite coating obtained in Example 1 exhibits lower surface roughness and more uniform three-dimensional morphology, indicating that the introduction of the Ti bonding layer and TiN transition layer helps to improve the deposition and growth state of the subsequent AlTiN functional carrier layer and CrN top layer, reduce local defects and surface height fluctuations, thereby improving the surface integrity of the coating.

[0076] Nanoindentation tests were performed on the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1 and the AlTiN / CrN composite coating prepared in Comparative Example 3, respectively. The results are as follows: Figure 9 As shown. By Figure 9(a) As can be seen, the AlTiN / CrN composite coating prepared in Comparative Example 3 has a hardness of 24.35 GPa and an elastic modulus of 327 GPa, indicating that it possesses certain hardness and load-bearing capacity under the action of the CrN top layer, but its overall mechanical properties are still relatively limited. In contrast, the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1 has a hardness increased to 33.58 GPa and an elastic modulus of 361.99 GPa, indicating that the overall load-bearing capacity and deformation resistance of the coating are further enhanced after the introduction of the Ti bonding layer and the TiN transition layer. Figure 9 (b) As can be seen, the H / E and H of the AlTiN / CrN composite coating prepared in Comparative Example 3 are... 3 / E 2 The values ​​were 0.074 and 0.130, respectively, while the H / E and H of the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1 were... 3 / E 2 The H / E ratios were increased to 0.093 and 0.289 GPa, respectively. This increase in H / E indicates that the coating of Example 1 exhibits better elastic recovery. 3 / E 2 The improvement indicates that it has a stronger resistance to plastic deformation. It can be seen that, compared with the AlTiN / CrN composite coating without a Ti / TiN transition layer, the improvement in mechanical properties of the multilayer composite coating obtained in Example 1 does not come solely from the CrN top layer, but from the synergistic strengthening effect among the Ti bonding layer, TiN transition layer, AlTiN functional load-bearing layer and CrN top layer, reflecting the comprehensive advantages of the "transition layer - functional load-bearing layer - protective top layer" system design.

[0077] Scratch adhesion tests were performed on the AlTiN / CrN composite coating prepared in Comparative Example 3 and the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1. The results are as follows: Figure 10 As shown. By Figure 10 (a) As can be seen, the AlTiN / CrN composite coating prepared in Comparative Example 3 exhibits relatively gradual changes in frictional force in the early and middle sections during scratch loading, but shows significant fluctuations and sudden increases in the higher load region. Obvious localized damage characteristics are observed at the scratch end, indicating that this coating is more prone to interfacial instability and localized spalling under high loads. This phenomenon is mainly related to the absence of a Ti bonding layer and a TiN transition layer. The interfacial transition between the AlTiN / CrN composite coating and the WC-12Co cemented carbide substrate is insufficient, making it prone to localized stress concentration under gradually increasing loads. Figure 10(b) As can be seen, the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1 exhibits a more stable overall curve during scratch loading. Significant instability and abrupt changes mainly occur in the higher load region, and the degree of localized peeling and damage in the scratch morphology is relatively mild, indicating that this multilayer composite coating has better film-substrate bonding stability and anti-peeling ability. Compared with Comparative Example 3, the Ti bonding layer in Example 1 enhances the interfacial bonding between the coating and the WC-12Co substrate, and the TiN transition layer alleviates the stress abrupt changes between the AlTiN functional support layer and the substrate, thereby improving the structural integrity of the coating under gradually increasing loads. These results demonstrate that the synergistic design among the Ti bonding layer, TiN transition layer, AlTiN functional support layer, and CrN top layer helps improve the coating's adhesion and failure resistance.

[0078] A comparative test of reciprocating friction and wear under atmospheric conditions was conducted on the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1 and the AlTiN / CrN composite coating prepared in Comparative Example 3. Figure 11 (a)- Figure 11 As shown in (d), the results indicate that under atmospheric loads of 6 N, 8 N, and 10 N, the friction coefficients of the multilayer composite coating obtained in Example 1 are all lower than those of the AlTiN / CrN composite coating prepared in Comparative Example 3, and the wear rate is significantly lower, demonstrating better wear resistance and service stability. Taking an atmospheric load of 10 N as an example, the wear rate of the AlTiN / CrN composite coating prepared in Comparative Example 3 is 42.06 × 10⁻⁶. -7 mm 3 ·N -1 ·m -1 The wear rate of the multilayer composite coating obtained in Example 1 was reduced to 25.36 × 10⁻⁶. -7 mm 3 ·N -1 ·m -1 This result further confirms the synergistic strengthening effect between the Ti bonding layer, TiN transition layer, AlTiN functional carrier layer, and CrN top layer.

[0079] Using TC4 titanium alloy as the workpiece, AlTiN / CrN composite coatings (Comparative Example 3) and Ti / TiN / AlTiN / CrN multilayer composite coatings (Example 1) were prepared on WC-12Co carbide cutting tools. End milling comparison tests were conducted, and the wear morphology and elemental distribution changes of the rake face of the two types of coated tools under different cumulative cutting times were recorded. The results are as follows: Figure 12 and Figure 13 As shown.

[0080] like Figure 12 (a)- Figure 12As shown in (j), in the initial cutting stage (T1) of Comparative Example 3, the AlTiN / CrN composite coated tool still maintained a certain integrity on the rake face, but local ploughing, adhesion spots, and slight wear marks appeared in the tool tip and chip contact area. As the cutting time increased to stages T3 and T5, the wear area gradually expanded, and more obvious adhesion transfer and local spalling appeared on the rake face surface. This indicates that although the AlTiN / CrN composite coating has the surface protection effect of the CrN top layer, the lack of a Ti bonding layer and a TiN transition layer results in insufficient interfacial transition between the coating and the WC-12Co substrate, making it more prone to local stress concentration and interfacial damage under continuous thermo-mechanical-friction coupling. By stages T7 and T9, the wear near the tool tip further worsened, with enhanced signals of matrix elements W and Co in some areas, while the signals of coating elements such as Ti, Al, N, and Cr weakened, indicating increased local coating consumption and substrate exposure. Therefore, the coated tool of Comparative Example 3 is prone to coating spalling, adhesion transfer, and premature substrate exposure during long-term cutting of TC4 titanium alloy, and its service stability remains insufficient.

[0081] like Figure 13 (a)- Figure 13 As shown in (j), the Ti / TiN / AlTiN / CrN multilayer composite coated tool prepared in Example 1 exhibits better coating integrity under the same cutting conditions. In the initial cutting stage (T1), the rake face is relatively intact, with only a few fine wear marks and localized adhesion spots visible along the cutting direction. As the cutting time increases to stages T3, T5, and T7, although the wear area gradually expands, the coating elements Cr, N, Ti, and Al remain distributed in some wear areas, indicating that the coating has not yet undergone rapid overall peeling. By stage T9, a composite wear zone appears on the tool surface, consisting of residual coating, an adhesion transfer layer, and locally exposed substrate, exhibiting a progressive wear process. Compared to Comparative Example 3, the Ti bonding layer and TiN transition layer in the coated tool of Example 1 enhance the interfacial bonding stability between the coating and the WC-12Co substrate. The AlTiN functional load-bearing layer provides the main load support, and the CrN top layer helps reduce the adhesion transfer and repeated shearing tearing of TC4 titanium alloy on the tool surface. Therefore, the Ti / TiN / AlTiN / CrN multilayer composite coating prepared in Example 1 can delay coating peeling and substrate exposure, and improve the service stability of coated tools in the end milling process of TC4 titanium alloy.

[0082] A comprehensive analysis of the test results from Comparative Examples 1-3 shows that the multilayer composite structure design of this invention is crucial for improving the overall performance of the coating. For the single-layer AlTiN coating corresponding to Comparative Example 1, its structure lacks a Ti bonding layer, a TiN transition layer, and a CrN top layer. Experimental results show that the coating surface has numerous arc-shaped particles and local defects, and insufficient film-substrate interface transition. During friction and wear and TC4 titanium alloy cutting, coating wear propagation and substrate exposure are more likely to occur. At the T9 stage, a large area of ​​material loss occurs near the tool tip, and the W and Co matrix element signals are significantly enhanced in the EDS results, indicating that the long-term protective capability of the single-layer AlTiN coating is insufficient and cannot simultaneously meet the requirements of interface bonding and surface protection. For the Ti / TiN / AlTiN multilayer coating corresponding to Comparative Example 2, its structure includes a Ti bonding layer and a TiN transition layer, but lacks a CrN top layer. Experimental results show that compared with the single-layer AlTiN coating, the Ti / TiN / AlTiN multilayer coating exhibits improved interfacial bonding and wear resistance, with a relatively slower wear propagation rate. This indicates that the Ti bonding layer and TiN transition layer can improve the interfacial matching relationship between the film and the substrate. However, due to the lack of a CrN top layer, the coating still experiences adhesion transfer, localized wear-through, and substrate exposure during the cutting of TC4 titanium alloy. The surface anti-adhesion and shear protection capabilities remain insufficient, particularly in suppressing titanium alloy adhesion transfer. For the AlTiN / CrN composite coating corresponding to Comparative Example 3, the CrN top layer improves the surface friction state and provides some anti-adhesion capability. However, due to the absence of a Ti bonding layer and a TiN transition layer, the interfacial transition is insufficient, making it prone to localized peeling and substrate exposure during high-load friction and wear and the cutting of TC4 titanium alloy. In conjunction with the aforementioned... Figure 11 The friction and wear results show that the wear rate of Comparative Example 3 is higher than that of the complete multilayer composite coating obtained in Example 1, indicating that setting the CrN top layer alone cannot fully solve the problems of interface bonding and high-load peeling.

[0083] Examples 2 and 3 correspond to the preparation results under the lower and higher process parameters of the present invention, respectively. The layer thickness and mechanical property results of Examples 2 and 3 show that, within the process window defined by the present invention, a multilayer composite structure consisting of a Ti bonding layer, a TiN transition layer, an AlTiN functional support layer, and a CrN top layer can be obtained sequentially. Furthermore, the thickness of each layer, the total thickness, and the thickness ratio of the CrN top layer to the AlTiN functional support layer are all within the range defined by the present invention. Simultaneously, the hardness of the coatings in Examples 2 and 3 are 33.12 GPa and 33.94 GPa, respectively; the elastic modulus is 359.20 GPa and 364.30 GPa, respectively; the H / E ratio is 0.092 and 0.093, respectively; and the H³ / E² ratio is 0.281 GPa and 0.295 GPa, respectively. This indicates that they all possess good elastic recovery and resistance to plastic deformation, supporting the feasibility, stability, and mechanical property advantages of the process parameter range described in the present invention.

[0084] In summary, relying solely on a single functional layer or partial layer structure cannot simultaneously meet the composite requirements of strong interfacial bonding, efficient stress transition, main load-bearing capacity, and surface anti-adhesion. Only through the systematic and collaborative design of the Ti bonding layer, TiN transition layer, AlTiN functional layer, and CrN thin top layer can the coating achieve a comprehensive improvement in interfacial stability, overall load-bearing capacity, and surface protection performance, thus proving the necessity and innovation of the multi-layer composite structure design of this invention.

[0085] like Figure 1As shown, the Ti / TiN / AlTiN / CrN multilayer coating prepared by the above process in this invention begins with argon ion etching of a WC-12Co cemented carbide substrate to activate the surface and enhance the adhesion of subsequent film layers. Subsequently, a multi-arc ion plating process is used to sequentially deposit a Ti bonding layer, a TiN transition layer, an AlTiN functional load-bearing layer, and a CrN top layer, thus forming a clear multilayer composite structure. This structure is optimized, with each layer having a clear function and forming a synergistic strengthening effect: the bottom Ti bonding layer aims to enhance the interfacial bonding strength between the coating and the substrate; the TiN transition layer above it is used to mitigate the stress gradient between the AlTiN layer and the Ti bonding layer, improving interlayer bonding stability; the AlTiN, as the main functional layer, provides the high hardness and main load-bearing capacity required for the coating; and the outermost CrN is an independently deposited thin layer of nitride, mainly playing a role in anti-adhesion, anti-shear, and surface protection, delaying material adhesion and early coating failure during titanium alloy cutting. This gradient structure, with each layer performing its specific function and coupled with other layers, is synergistically controlled by specific thickness ratios and deposition parameters. This combination endows the coating with comprehensive performance, including high bonding strength, good toughness matching, and excellent surface protection. Simultaneously, a clear functional division exists between the CrN top layer and the AlTiN functional load-bearing layer. The AlTiN layer primarily provides hardness and load support, while the thin CrN top layer mainly provides surface anti-adhesion and shear protection. The Ti bonding layer and TiN transition layer improve the interfacial bonding and interlayer stress transition, thereby enabling the coating to exhibit better structural stability during friction and wear and the cutting of TC4 titanium alloys.

[0086] Based on the specific structure described above, the preparation method of this invention has good overall technical effects. This method employs a mature multi-arc ion plating physical vapor deposition process, with pretreatment cleaning, ion activation, and layered deposition as the core processes. Key process parameters are clearly defined, exhibiting good process repeatability and facilitating implementation on existing production lines. It is suitable for large-scale surface strengthening of WC-12Co cemented carbide products. The Ti / TiN / AlTiN / CrN multilayer composite wear-resistant coating obtained by this method is particularly suitable for surface strengthening of cemented carbide cutting tools and wear-resistant parts. Its multilayer structure, through the synergistic effect of each functional layer, can reduce the risk of early peeling of the coating under alternating loads and titanium alloy adhesion transfer conditions, thereby extending the effective protection time and service stability of the coating. When cutting difficult-to-machine materials such as TC4 titanium alloy, this coating can slow down substrate exposure, suppress workpiece material adhesion transfer and sudden wear increases, and improve the cutting performance and service reliability of WC-12Co cemented carbide cutting tools. Therefore, this invention has clear technical advantages and engineering application value.

[0087] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0088] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for preparing a composite wear-resistant coating on WC-12Co cemented carbide, characterized in that, Includes the following steps: Step S1: The WC-12Co cemented carbide substrate is subjected to spray cleaning, ultrasonic cleaning, rinsing and drying pretreatment in sequence; Step S2: Place the pretreated substrate into a multi-arc ion plating apparatus, evacuate the vacuum, heat up, and perform ion activation cleaning. Step S3: At a deposition temperature of 390–410 °C, a multi-arc ion plating process is used to sequentially deposit a Ti bonding layer, a TiN transition layer, an AlTiN functional bearing layer, and a CrN top layer on the activated and cleaned substrate surface, thereby forming a multi-layer composite wear-resistant coating.

2. The method for preparing the composite wear-resistant coating on WC-12Co cemented carbide according to claim 1, characterized in that, In step S1, the temperature of the spray cleaning is 55-65 ℃ and the time is 270-330 s; the temperature of the ultrasonic cleaning is 55-65 ℃ and the time is 570-630 s; the temperature of the rinsing is 45-55 ℃ and the time is 270-330 s; and the temperature of the drying is 110-130 ℃ and the time is 870-930 s.

3. The method for preparing the composite wear-resistant coating on WC-12Co cemented carbide according to claim 1, characterized in that, In step S2, when the background vacuum of the device reaches 5.0 × 10⁻⁶ -2 After Pa, the temperature is raised to 390–410 °C and held; argon and hydrogen are introduced for ion activation cleaning for 115–125 min.

4. The method for preparing the composite wear-resistant coating on WC-12Co cemented carbide according to claim 1, characterized in that, In step S3, When depositing the Ti bonding layer, a pure Ti target is used, and the deposition is carried out in a pure Ar atmosphere with a substrate bias voltage of 85–95 V and a working pressure of 1.2–1.4 Pa. When depositing the TiN transition layer, a pure Ti target was used, and the deposition was carried out in an Ar and N2 reaction atmosphere. The substrate bias voltage was 85–95 V, and the working pressure was 0.7–0.9 Pa. When depositing the AlTiN functional carrier layer, a TiAl target is used, and the deposition is carried out in an Ar and N2 reaction atmosphere. The substrate bias voltage is 65-75 V, and the working pressure is 3.3-3.7 Pa. When depositing the CrN top layer, a pure Cr target was used, and the deposition was carried out in an Ar and N2 reaction atmosphere. The substrate bias voltage was 125–135 V, and the working pressure was 0.9–1.1 Pa.

5. The method for preparing the composite wear-resistant coating on WC-12Co cemented carbide according to claim 4, characterized in that, In the TiAl target material, the atomic ratio of Ti to Al is 33:

67.

6. The method for preparing the composite wear-resistant coating on WC-12Co cemented carbide according to claim 4, characterized in that, The total deposition time of the coating is 8550–8650 s; during the deposition process, Ar is introduced throughout at a flow rate of 345–355 sccm; N2 is introduced only during the deposition stages of the TiN transition layer, AlTiN functional carrier layer, and CrN top layer at a flow rate of 845–855 sccm; the substrate bias is applied using a DC pulse method with a pulse frequency of 30 kHz, a duty cycle of 60%–90%, an arc current of 120 A, and a workpiece gantry rotation speed of 1.8–2.2 r / min.

7. A composite wear-resistant coating on WC-12Co cemented carbide, characterized in that, The multilayer composite wear-resistant coating is prepared by the method described in any one of claims 1 to 6, and the total thickness of the coating is 2.93 to 3.40 μm. The thickness of the Ti bonding layer is 0.03–0.05 μm, the thickness of the TiN transition layer is 0.18–0.25 μm, the thickness of the AlTiN functional bearing layer is 2.4–2.7 μm, and the thickness of the CrN top layer is 0.32–0.40 μm.

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