AlCrSiWN / CrMoN nano-multilayer composite coating with both high hardness and self-lubricating properties and its preparation process

Abstract

This invention discloses an AlCrSiWN / CrMoN nano-multilayer composite coating with both high hardness and self-lubricating properties, and its preparation process, belonging to the field of coating technology. This multilayer composite coating is a modulated coating formed by alternating deposition of a high-hardness AlCrSiWN layer and a self-lubricating CrMoN layer, with a total thickness of 3-4 μm and a periodic thickness of 0.011-0.038 μm. The coating preparation process is as follows: first, an AlCrN transition layer with a columnar crystal structure is prepared; then, the AlCrSiWN and CrMoN targets are simultaneously activated, and the rotation speed of the rotating frame in the vacuum deposition chamber is adjusted to 0.6 r / min-1.5 r / min to prepare an AlCrSiWN / CrMoN nano-multilayer composite coating with nanoscale modulated periodic alternation of hard and soft layers. The alternating hard and soft multilayer structure can maintain the high hardness of the coating while improving its toughness and self-lubricating properties, effectively inhibiting crack propagation.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to an AlCrSiWN / CrMoN nano-multilayer composite coating with both high hardness and self-lubricating properties, and its preparation process. Background Technology

[0002] In high-speed dry cutting of difficult-to-machine materials, challenges include rapid tool wear, tool adhesion to the workpiece, and high temperatures in the cutting zone. Soft coatings with good self-lubricating properties generate a low-shear-modulus Magnéli phase lubricating film during cutting, reducing the adhesion tendency between the tool and workpiece, decreasing frictional resistance at the cutting interface, and effectively suppressing tool wear and cutting heat accumulation, thus extending tool life. However, CrMoN self-lubricating coatings suffer from low hardness and insufficient wear resistance; the protective effect of a single-layer soft coating is often short-lived, making it difficult to provide long-term effective protection for the tool substrate. AlCrSiWN hard coatings have high hardness, but their insufficient toughness and high coefficient of friction limit their application in high-speed dry cutting.

[0003] By constructing a nano-multilayer coating structure with alternating hard and soft layers, columnar crystal growth can be effectively suppressed, promoting a more uniform and dense coating microstructure. Furthermore, the multilayer interface can inhibit crack initiation and propagation, acting as a stress buffer. By combining a high-hardness coating with a self-lubricating coating in multiple layers, the performance of both can be synergistically optimized, retaining the excellent mechanical properties of the high-hardness layer while also possessing the friction-reducing advantages of the self-lubricating layer. This invention, by controlling the rotation speed of the rotating frame within the vacuum deposition chamber, alternately deposits an AlCrSiWN high-hardness layer and a CrMoN self-lubricating layer, and systematically studies the elemental composition, phase composition, microstructure, mechanical properties, and tribological behavior of the AlCrSiWN / CrMoN nano-multilayer composite coating. Summary of the Invention

[0004] To address the significant bottlenecks in high-speed dry cutting of the aforementioned difficult-to-machine materials, where the machining process involves abnormally high cutting forces and temperatures, leading to easy tool wear and severely restricting machining efficiency and quality, this invention aims to provide an AlCrSiWN / CrMoN nano-multilayer composite coating with both high hardness and self-lubricating properties, along with its preparation process. The invention employs arc ion plating technology, simultaneously activating both the AlCrSiW and CrMo targets. By adjusting the rotation speed of the rotating frame within the vacuum coating chamber, the interlayer thickness of the AlCrSiWN high-hardness layer and the CrMoN self-lubricating layer is controlled, thus preparing an AlCrSiWN / CrMoN nano-multilayer composite coating that combines high hardness and self-lubricating properties.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] An AlCrSiWN / CrMoN nano-multilayer composite coating with both high hardness and self-lubricating properties is deposited on the surface of a cemented carbide substrate. It is a modulated coating formed by alternating deposition of an AlCrSiWN high-hardness layer and a CrMoN self-lubricating layer. The total thickness of the multilayer composite coating is 3~4 μm, and the periodic thickness is 0.011~0.038 μm. As a functional layer, this nano-multilayer film can effectively inhibit crack propagation due to its good toughness.

[0007] Furthermore, the modulation ratio of this multilayer composite coating (the thickness ratio of the AlCrSiWN high-hardness layer to the CrMoN self-lubricating layer) is 2:1 to 1:2.

[0008] Furthermore, the chemical composition of the AlCrSiWN / CrMoN nano-multilayer composite coating, by atomic percentage, is as follows: Al 6.74~8.73%, Cr 33.74~35.59%, Mo 6.36~8.13%, Si 1.71~2.69%, W 1.06~1.98%, and N 46.17~48.76%.

[0009] Furthermore, the microstructure of the AlCrSiWN / CrMoN nano-multilayer composite coating includes hcp-Cr2N, fcc-CrN, h-(Cr,W)N2, h-W2N, t-Mo2N, and c-WN phases.

[0010] Furthermore, an AlCrN transition layer is deposited between the multilayer composite coating and the substrate. The AlCrN transition layer has a columnar crystal structure with a thickness of 100~120 nm and exhibits good bonding performance with the substrate.

[0011] Furthermore, the AlCrSiWN / CrMoN nano-multilayer composite coating achieves a hardness of 43.42 GPa, an elastic modulus of 467.88 GPa, and H / E and H 3 / E *2 They can reach 0.097 and 0.31 GPa respectively.

[0012] Furthermore, the AlCrSiWN / CrMoN nanolayered composite coating exhibits a friction coefficient and wear rate as low as 0.44 and 1.68 × 10⁻⁶, respectively. -10 mm 3 / (N·mm).

[0013] The preparation process of the AlCrSiWN / CrMoN nano-multilayer composite coating with both high hardness and self-lubricating properties is as follows: using arc ion plating technology, first depositing an AlCrN transition layer on the substrate, and then alternately depositing an AlCrSiWN high-hardness layer and a CrMoN self-lubricating layer to obtain the AlCrSiWN / CrMoN nano-multilayer composite coating.

[0014] Furthermore, during the deposition of the AlCrSiWN / CrMoN nano-multilayer composite coating, N2 was introduced into the vacuum deposition chamber, and the AlCrSiW and CrMo targets were simultaneously activated. By adjusting the rotation speed of the rotating frame within the vacuum deposition chamber, the AlCrSiWN high-hardness layer and the CrMoN self-lubricating layer were deposited alternately to ultimately obtain the multilayer composite coating. During the deposition process, the vacuum level was controlled at 3 × 10⁻⁶. -3 The deposition temperature is 400-500 ℃ and the rotation speed is 0.5 r / min~1.5 r / min. At this rotation speed, the effective deposition time of the substrate in front of the AlCrSiW target and the CrMo target is different, thereby controlling the layer thickness of the AlCrSiWN high-hardness layer and the CrMo self-lubricating layer. The resulting soft-hard alternating nano-multilayer film has high hardness and good self-lubricating properties.

[0015] Furthermore, the process specifically includes the following steps:

[0016] (1) After ultrasonic cleaning and drying, the substrate is fixed on the sample holder and suspended on the rotating frame in the coating chamber to ensure that the substrate is facing the coating target.

[0017] (2) Evacuate the coating chamber to a vacuum level of 3.0 × 10⁻⁶. -3 Heat the vacuum coating chamber to 400-500 ℃ and hold it at that temperature for 30 min at a pressure above Pa.

[0018] (3) Etching and cleaning: Turn on the etching Ti target and etch and clean the substrate in an Ar atmosphere;

[0019] (4) Deposition of AlCrN transition layer: Introduce N2 and turn on AlCr target, deposition time is 30~35 min;

[0020] (5) Deposition of AlCrSiWN / CrMoN nanomultilayer film: The N2 flow rate is adjusted to 1260~1390 sccm, and the AlCrSiW target and CrMo target are turned on at the same time. The AlCrSiW target current is controlled to be 120~160 A and the CrMo target current is controlled to be 120~150 A. The total deposition time is 100-130 min, and AlCrSiWN / CrMoN nanomultilayer film with alternating AlCrSiWN high hardness layer and CrMoN self-lubricating layer is obtained.

[0021] Further, in step (3), the etching and cleaning process is as follows: after the vacuum coating chamber is heated and kept at a constant temperature for 30 minutes, Ar is introduced, with an Ar flow rate of 150~300 sccm (preferably 170~190 sccm), the deposition pressure is controlled at 0.26~0.35Pa (preferably 0.28~0.32 Pa), and the Ti target is etched, with the Ti target arc source current of 120~140 A, the DC bias voltage is set to increase from -10 V to -180 V, and the etching and cleaning time is 60~90 minutes; after etching is completed, the etching arc source and bias voltage are turned off, the gas is turned off, and the furnace is pumped back for 5~10 minutes to remove the residual gas; the etching and cleaning process removes impurities such as oxides from the substrate surface and activates the substrate surface.

[0022] Further, in step (4), after etching and cleaning, an AlCrN transition layer is deposited. During the deposition process, N2 with a flow rate of 1220~1280 sccm is introduced, the deposition pressure is 3.2~4.5 Pa, the AlCr target current is 120~140 A, and the DC bias voltage is -40~-60 V.

[0023] Furthermore, in step (5), when depositing AlCrSiWN / CrMoN nanolayered films, the target arc source current of AlCrSiW is 130-155A, the target arc source current of CrMo is 130-145A, the rotation speed of the rotating frame is 0.6 r / min~1.3 r / min, the deposition pressure is 3.5~4 Pa, and the DC bias voltage is -120~-160 V.

[0024] Furthermore, during step (5) when depositing the AlCrSiWN / CrMoN nanomultilayer film, the intensity of the diffraction peaks of the fcc-CrN phase (220) crystal plane and the c-WN phase (311) crystal plane in the obtained nanomultilayer composite coating gradually increases with the increase of the rotation speed of the rotating frame.

[0025] The design mechanism of this invention is as follows:

[0026] This invention employs arc ion plating technology to deposit an AlCrSiWN / CrMoN nano-multilayer composite coating on a cemented carbide sample.

[0027] Mo-containing compounds exhibit structural stability, excellent hardness, and continuous self-lubricating ability at high temperatures, making them suitable for cutting conditions across a wide temperature range, from room temperature to high temperatures. Even under extreme cutting conditions of high temperature and high load, the layered MoO3 solid lubricant in the self-lubricating coating maintains good self-lubricating properties. Adding lubricating elements to traditional hard coatings to prepare high-performance tool coatings with self-lubricating functions combines the high hardness and wear resistance of traditional hard coatings with the self-lubricating and low-friction characteristics provided by the lubricating phase, thus extending tool life and improving surface finish during machining.

[0028] The advantages and beneficial effects of this invention are as follows:

[0029] 1. The AlCrSiWN / CrMoN nano-multilayer composite coating prepared by this invention has high wear resistance and obvious wear resistance effect.

[0030] 2. The AlCrSiWN / CrMoN nano-multilayer composite coating of the present invention maintains the high hardness of the AlCrSiWN layer and achieves the friction reduction effect of the coating by introducing a CrMoN self-lubricating layer, thus preparing a nano-multilayer composite coating with both high hardness and self-lubricating properties.

[0031] 3. The AlCrSiWN / CrMoN nano-multilayer composite coating of this invention shows broad application prospects in the field of difficult-to-machine materials, can significantly improve cutting efficiency, and greatly extend tool service life.

[0032] 4. The AlCrSiWN / CrMoN nano-multilayer composite coating of this invention has both excellent mechanical and tribological properties, and the coated tool is capable of high-speed heavy-load continuous machining conditions. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the AlCrSiWN / CrMoN nano-multilayer composite coating structure prepared by arc ion plating technology in Example 1.

[0034] Figure 2 The XRD patterns of AlCrSiWN / CrMoN nano-multilayer composite coatings deposited at different rotation speeds within a vacuum chamber using arc ion plating technology, as shown in Example 1.

[0035] Figure 3 The surface morphology of AlCrSiWN / CrMoN nano-multilayer composite coatings deposited at different rotation speeds within a vacuum chamber using arc ion plating technology, as shown in Example 1.

[0036] Figure 4 The cross-sectional morphology of the AlCrSiWN / CrMoN nano-multilayer composite coatings deposited at different rotation speeds within a vacuum cavity using arc ion plating technology, as shown in Example 1.

[0037] Figure 5 The hardness (HIT) and elastic modulus (EIT) of AlCrSiWN / CrMoN nano-multilayer composite coatings deposited at different rotation speeds within a vacuum cavity using arc ion plating technology, as shown in Example 1.

[0038] Figure 6The H / E and H values ​​of AlCrSiWN / CrMoN nanolayered composite coatings deposited at different rotation speeds within a vacuum cavity using arc ion plating technology, as shown in Example 1. 3 / E *2 .

[0039] Figure 7 The critical load and scratch morphology of AlCrSiWN / CrMoN nano-multilayer composite coatings deposited at different rotation speeds within a vacuum chamber using arc ion plating technology, as shown in Example 1.

[0040] Figure 8 The friction coefficient curves are shown for the AlCrSiWN / CrMoN nano-multilayer composite coatings deposited at different rotation speeds within a vacuum chamber using arc ion plating technology, as shown in Example 1.

[0041] Figure 9 The friction coefficient and wear rate of AlCrSiWN / CrMoN nano-multilayer composite coatings deposited at different rotation speeds within a vacuum cavity using arc ion plating technology, as shown in Example 1.

[0042] Figure 10 The two-dimensional wear marks of AlCrSiWN / CrMoN nano-multilayer composite coatings deposited at different rotation speeds within a vacuum chamber using arc ion plating technology in Example 1 are shown below: (a) 0.6 r / min; (b) 0.9 r / min; (c) 1.2 r / min; (d) 1.5 r / min.

[0043] Figure 11 The image shows the three-dimensional wear morphology of the AlCrSiWN / CrMoN nano-multilayer composite coating deposited at a rotation speed of 0.6 r / min using arc ion plating technology, as shown in Example 1.

[0044] Figure 12 The image shows the three-dimensional wear morphology of the AlCrSiWN / CrMoN nano-multilayer composite coating deposited at a rotation speed of 0.9 r / min using arc ion plating technology, as shown in Example 1.

[0045] Figure 13 The image shows the three-dimensional wear morphology of the AlCrSiWN / CrMoN nano-multilayer composite coating deposited at a rotation speed of 1.2 r / min using arc ion plating technology, as shown in Example 1.

[0046] Figure 14 The image shows the three-dimensional wear morphology of the AlCrSiWN / CrMoN nano-multilayer composite coating deposited at a rotation speed of 1.5 r / min using arc ion plating technology, as shown in Example 1. Detailed Implementation

[0047] The present invention will be further described in detail below through embodiments.

[0048] This invention employs a "nanocomposite + multilayer composite" method to prepare a nano-multilayer composite coating with alternating soft and hard surfaces. While maintaining the high hardness of the coating, it reduces the friction coefficient of traditional hard coatings, improves the lubrication performance of the coating, reduces heat conduction to the cutting tool during cutting, enhances the thermal stability of the coating, and improves the service life of the cutting tool and the surface quality of the machined surface.

[0049] In the following embodiments, a high-purity Ti target is used for etching and cleaning, a high-purity AlCr alloy target is used for depositing a transition layer, and a high-purity AlCrSiW alloy target and a high-purity CrMo alloy target are used for depositing nanoscale multilayer functional layers. The purity of the Ti target, AlCr alloy target, AlCrSiW alloy target, and CrMo alloy target is all above 99.95%.

[0050] In AlCr alloy targets, Al:Cr = 70:30 (atomic ratio); in AlCrSiW alloy targets, Al:Cr:Si:W = 52:28:15:5 (atomic ratio); and in CrMo alloy targets, Cr:Mo = 85:15 (atomic ratio).

[0051] Example 1:

[0052] This embodiment describes the preparation of AlCrSiWN / CrMoN nano-multilayer composite coatings at different rotational speeds within a vacuum chamber.

[0053] This embodiment involves depositing an AlCrSiWN / CrMoN nano-multilayer composite coating on a cemented carbide substrate (25 mm × 25 mm × 3 mm) of grade YG8 using arc ion plating technology. The specific operational steps are as follows:

[0054] (1) Pretreatment before coating: The cemented carbide substrate is polished and then cleaned. The cleaning process is carried out in an ultrasonic cleaner, using acetone and alcohol as solvents in sequence, and ultrasonic cleaning for 15 min each. After cleaning, the sample is dried with high-purity nitrogen. Then, the sample is installed in the fixture and pressed and fixed. After the vacuum chamber is depressurized, the furnace door is opened, and the clamped substrate is fixed on the rotating frame in the coating chamber with iron wire. The position of the substrate is adjusted so that its surface faces the target material.

[0055] (2) Vacuuming: The coating deposition process needs to be carried out in a high vacuum environment. The vacuuming process of the coating system is divided into two stages: First, rough evacuation is performed, that is, the pre-evacuation pump and the Roots pump are started to reduce the pressure in the vacuum chamber to below 30 Pa; then fine evacuation is performed, at which time the turbomolecular pump is turned on to further increase the system vacuum to 3×10 Pa. -4 Pa or above.

[0056] (3) Heating and constant temperature: Set the heating temperature of the coating system to 500 ℃, and keep it at this temperature for 30 min after heating is completed.

[0057] (4) Etching and Cleaning: The simultaneous etching process of argon ions and titanium metal ions (IET) is adopted. This process relies on various active components in the plasma, such as ions, electrons, active groups, metastable excited nuclides, and photons. These components work together on the material surface, effectively removing surface contaminants and activating its surface chemical activity through continuous particle bombardment. The specific process parameters are: argon flow rate 180 sccm, deposition pressure 0.31 Pa, and two etching Ti targets are turned on, with the arc source current of the Ti targets being 140 A. The DC bias voltage is gradually increased from -10 V to -150 V, and the etching time is 75 min. After etching is completed, the etching arc source and bias voltage are turned off, the gas is turned off, and the furnace is evacuated for 10 min to remove residual gas. The etching and cleaning process removes impurities such as oxides from the substrate surface and activates the substrate surface.

[0058] (5) Transition layer deposition: Turn on the AlCr target, introduce N2 flow rate of 1230 sccm, stabilize the deposition pressure at 3.3Pa, AlCr target arc source current of 130 A, DC bias of -40 V, and deposit for 30 min.

[0059] (6) Deposition of AlCrSiWN / CrMoN nanolayer functional layers: AlCrSiW and CrMo targets are turned on simultaneously, with the arc source current of AlCrSiW target being 150A and the arc source current of CrMo target being 140A; the N2 flow rate is adjusted to 1310 sccm to stabilize the pressure at 3.6Pa, the rotation speeds of the rotating frame are 0.6 r / min, 0.9 r / min, 1.2 r / min and 1.5 r / min respectively, the DC bias is -150 V, and the deposition time is 120 min.

[0060] (7) Cooling in the furnace: After the coating is completed, all arc sources and bias voltages are turned off, and the coated sample is cooled in the vacuum furnace.

[0061] The microstructure and performance of the AlCrSiWN / CrMoN nanolayered composite coatings deposited at different rotation speeds within the vacuum chamber prepared in this embodiment were characterized and tested, as detailed below:

[0062] The phase structure of the coating was characterized by X-ray diffraction (XRD). The test was conducted using Cu target Kα radiation (λ = 0.154056 nm). Diffraction patterns in the range of 20° to 80° (2θ) were acquired in step scan mode under tube voltage of 40 kV and tube current of 40 mA. The scan step size was 0.02° and the dwell time was 0.2 s per step.

[0063] The hardness and elastic modulus of the coating were tested using a nanoindenter (Anton Paar, TTX-NHT-3). To minimize the influence of the matrix effect, the indentation depth was controlled to not exceed one-tenth of the total coating thickness, and data from 15 measuring points were collected under the same conditions and averaged.

[0064] The film-substrate adhesion strength of the coating was evaluated using an Anton Paar RST-3 scratch tester. The test used a diamond indenter with a diameter of 200 μm, which scratched a 3 mm length at a speed of 6 mm / min under a set load of 100 N. All data were automatically collected and recorded by a computer.

[0065] The tribological properties of the coating were evaluated using an Anton Paar THT tribological testing machine. The experiment used Al₂O₃ spheres (hardness 22±1 GPa) with a diameter of 6 mm as the friction pair, and subjected to sliding friction over 180 m at a linear velocity of 0.1 m / s and a rotation radius of 6 mm under a normal load of 6 N. All tests were conducted in a constant temperature and humidity environment (22±3 ℃, relative humidity 30%), and each sample was tested three times to ensure data reliability.

[0066] The surface morphology of the worn coating was observed using a super depth-of-field microscope (Keyence VHX-1000C) and a white light interferometer. The wear rate was calculated using the formula W=V / (F×S) based on the wear volume V, normal load F and sliding distance S.

[0067] The AlCrSiWN / CrMoN nanolayered composite coating structure prepared in this embodiment is as follows: Figure 1 As shown, the bottom layer of the coating is an AlCrN transition layer, whose typical columnar crystal structure helps improve the bonding performance between the coating and the cemented carbide substrate. Above the functional layer is an AlCrSiWN / CrMoN nano-multilayer composite coating, formed by alternating deposition of AlCrSiWN and CrMoN layers. This is a modulated coating with a thickness of approximately 3 μm. This nano-multilayer functional layer exhibits high hardness and toughness, effectively reducing crack propagation, while also possessing a low coefficient of friction, thus improving the coating's wear resistance.

[0068] The chemical composition of the AlCrSiWN / CrMoN nano-multilayer composite coating prepared in this embodiment is shown in Table 1.

[0069] Table 1 Chemical composition (at.%) of AlCrSiWN / CrMoN nano-multilayer composite coating

[0070]

[0071] Figure 2The XRD patterns of AlCrSiWN / CrMoN nanolayered composite coatings deposited at different rotor speeds within the vacuum chamber are shown. As can be seen from the figures, the AlCrSiWN / CrMoN nanolayered composite coating mainly consists of hcp-Cr2N, fcc-CrN, h-(Cr,W)N2, h-W2N, t-Mo2N, and c-WN phases. With increasing rotor speed, the frequency of the substrate facing the target increases accordingly, thereby increasing the effective bombardment frequency. This process promotes the stoichiometry of the CrN and WN phases towards the ideal ratio, reduces the formation of amorphous or impurity phases, and ultimately enhances the diffraction peak intensity of the coating. When the rotor speed reaches the highest of 1.5 r / min, the frequency of the substrate facing the target per unit time increases significantly, enhancing the ion bombardment effect, which helps promote the formation of a uniform t-Mo2N phase. In contrast, at moderate rotation speeds of 0.9 r / min and 1.2 r / min, an imbalance occurs between the ion bombardment energy and the deposition rate, leading to localized inhomogeneities in the atomic arrangement within the coating, manifested as lattice distortion and compositional fluctuations. These structural defects ultimately result in broadening of the diffraction peaks on the t-Mo2N(200) crystal plane, which overlap with the (-1-11) crystal plane diffraction peaks of the hcp-Cr2N phase.

[0072] Figure 3 The surface morphology of AlCrSiWN / CrMoN nanolayered composite coatings deposited at different rotational speeds within the vacuum chamber is shown. At lower rotational speeds, the substrate is exposed to the high-density plasma region for a longer period, providing more favorable conditions for the deposition and coarsening of molten droplets. At a rotational speed of 0.6 r / min, the residence time of the substrate along the droplet's direction of motion is at its longest, making it easier for droplets to adhere and accumulate, forming larger surface particles. At this speed, due to the weak centrifugal force, surface tension and adhesion forces dominate, further intensifying the retention tendency and leading to the formation of numerous irregular clusters on the coating surface. As the rotational speed increases to 0.9 r / min, more pits caused by the peeling off of large particles are observed on the coating surface. When the rotational speed is further increased to 1.2 r / min, the residence time of particles and droplets on the substrate surface is significantly shortened, inhibiting the coarsening process. Consequently, the particle size is more uniform, the coating structure is denser, and the number of defects such as pores is reduced. At the highest rotational speed of 1.5 r / min, the number of droplets on the coating surface recovers somewhat. These droplets, once solidified, possess high surface energy, making them preferred sites for heterogeneous nucleation and inducing the epitaxial growth of local crystal clusters on their surface.

[0073] Figure 4The cross-sectional morphology of AlCrSiWN / CrMoN nanolayered composite coatings deposited at different rotation speeds within the vacuum chamber is shown. The AlCrSiWN / CrMoN nanolayered structure is clearly visible, with an AlCrN transition layer at the bottom. The surface of the transition layer is a modulated coating formed by alternating deposition of hard AlCrSiWN layers and soft CrMoN layers (modulation ratio (thickness ratio of the high-hardness AlCrSiWN layer to the self-lubricating CrMoN layer) is approximately 1:1). The AlCrN transition layer is approximately 110 nm thick and possesses a dense, ordered columnar crystalline structure. Its longitudinal growth behavior perpendicular to the substrate helps alleviate interfacial stress caused by differences in thermal expansion coefficients, inhibits coating peeling, and thus significantly improves the film-substrate bonding strength. With increasing rotation speed, the total coating thickness does not change significantly, but the layered structure becomes more dense and uniform. To enhance the structural continuity of the coating along the growth direction, AlCrSiW and CrMo targets are simultaneously activated during deposition, forming a multilayered alternating structure with nanoscale modulation periods. This structure introduces a large number of interfaces, which deflect cracks when they extend to the interfaces, effectively preventing further extension and improving the overall toughness of the coating.

[0074] Figure 5 The hardness (HIT) and elastic modulus (EIT) of AlCrSiWN / CrMoN nanolayered composite coatings deposited at different rotational speeds within a vacuum chamber are presented. A nanolayered structure design employing alternating hard and soft AlCrSiWN / CrMoN was adopted, achieving a simultaneous improvement in toughness while maintaining high coating hardness. The coating hardness initially increases and then decreases with increasing rotational speed. At a lower speed of 0.6 r / min, the coating surface exhibits a large accumulation of large particles and clusters, leading to decreased structural density and increased porosity, resulting in relatively low hardness. As the rotational speed increases, the size of surface particles and the number of clusters significantly decrease. According to the Hall-Page effect, grain refinement enhances the resistance to dislocation movement, thereby increasing the coating hardness. When the rotational speed reaches 1.2 r / min, the coating forms a smaller modulation period, and the interface density significantly increases. This structure not only alleviates stress concentration and inhibits crack propagation through coordinated deformation but also effectively hinders dislocation movement through periodic interfaces, further enhancing hardness and strength. At this point, both the coating hardness and elastic modulus reached their peak values, at 43.42 GPa and 467.88 GPa, respectively. Further increasing the rotational speed to 1.5 r / min reduced the thickness ratio of the AlCrSiWN hard layer to the CrMoN self-lubricating layer, making it easier for dislocations to cross the interface. Consequently, the coating hardness and elastic modulus decreased, with the lowest hardness value reaching 36.88 GPa.

[0075] Figure 6 Characteristic values ​​H / E and H of AlCrSiWN / CrMoN nanolayered composite coatings deposited at different rotation speeds within a vacuum chamber. 3 / E *2 The eigenvalue H / E is used to evaluate the toughness of the coating; the higher the eigenvalue H / E, the stronger the toughness of the coating. 3 / E *2 The characteristic value H represents the coating's resistance to plastic deformation. 3 / E *2 The higher the value, the stronger the coating's resistance to plastic deformation. The H / E ratio of the coating is related to H... 3 / E *2 The H / E value fluctuates with increasing rotational speed. Although hardness and toughness are often inversely related, this nano-multilayer structure successfully achieves simultaneous optimization of both properties through the synergistic effect between interface-induced crack deflection and the plastic deformation of the CrMoN soft layer. The coating exhibits the highest H / E value (0.097) at a rotational speed of 0.6 r / min. When the rotational speed increases to 1.2 r / min, the H / E value decreases further. 3 / E *2 The value reached a peak of 0.31 GPa, mainly attributed to the optimal thickness matching between the AlCrSiWN and CrMoN layers, resulting in an ideal synergy between hardness and toughness. The hard phase provides the basic hardness, while the soft phase absorbs energy through plastic deformation and reduces the elastic modulus, thus jointly promoting H... 3 / E *2 The value increases. When the rotational speed is further increased to 1.5 r / min, the insufficient thickness of the soft phase layer weakens its crack passivation ability, causing a simultaneous decrease in coating hardness and elastic modulus, with a more significant decrease in hardness, resulting in H / E and H³ / E. *2 The values ​​dropped to the lowest levels of 0.088 and 0.242 GPa, respectively.

[0076] Figure 7The critical load and scratch morphology of AlCrSiWN / CrMoN nanolayered composite coatings deposited at different rotational speeds within a vacuum chamber are shown (Lc2 in the figure refers to the load when the coating peels off over a large area and completely exposes the cemented carbide substrate). As the rotational speed increases, the number of multilayer interfaces formed in the coating gradually increases, while the critical load shows a trend of first increasing and then decreasing. At a rotational speed of 0.6 r / min, the acoustic emission signal shows significant fluctuations at approximately 65 N, corresponding to the onset of slight plastic deformation and wavy cracks in the scratched area; when the load continues to increase to 78.12 N, the coating peels off, and this load is determined to be the critical load. When the rotational speed increases to 0.9 r / min, the increase in coating hardness and elastic modulus enhances its overall load-bearing capacity and crack resistance, and the critical load increases accordingly. At 1.2 r / min, the critical load reaches its maximum value of 87.63 N. However, when the rotational speed further increases to 1.5 r / min, the number of interfaces per unit thickness further increases. Although the interface structure can improve fracture toughness through crack deflection, excessively high interface density can introduce defects such as lattice mismatch and dislocation accumulation, which become the origin of microcracks and ultimately cause the critical load to drop back to 80.94 N.

[0077] Figure 8 The friction coefficient curves of AlCrSiWN / CrMoN nanolayered composite coatings deposited at different rotational speeds within the vacuum chamber are shown. Due to its unique alternating hard / soft structure, the AlCrSiWN / CrMoN nanolayered coating exhibits a non-uniform distribution of contact stress during friction, leading to dynamic variations in the strength of the CrMoN lubricating phase in localized areas, resulting in significant fluctuations in the friction coefficient. When the rotational speed increases to 1.2 r / min and 1.5 r / min, the friction coefficient curves tend to stabilize. This is mainly because the higher speed enhances the centrifugal effect, making it difficult for droplets and large particles to accumulate locally on the surface, thus resulting in a more uniform distribution on the coating surface and a smoother morphology. The reduction of surface protrusions effectively reduces sudden load changes during friction, making the friction behavior more stable.

[0078] Figure 9The friction coefficient and wear rate of AlCrSiWN / CrMoN nanolayered composite coatings deposited at different rotational speeds within a vacuum chamber are presented. At a rotational speed of 0.6 r / min, the coating friction coefficient reaches its highest value of 0.54. This phenomenon is closely related to surface defects in the coating: during friction, surface particles undergo significant plastic deformation and detach, and these detached particles participate in friction as a third body, thus increasing the friction coefficient. When the rotational speed increases to 0.9 r / min, the coating hardness, elastic modulus, and critical load all increase simultaneously, resulting in improved overall performance. At a rotational speed of 1.2 r / min, the coating exhibits the best tribological properties, with its friction coefficient and wear rate decreasing to their lowest values ​​of 0.44 and 1.68 × 10⁻⁶, respectively. -10 mm 3 / (N·mm).

[0079] Figure 10 Two-dimensional wear track morphology of AlCrSiWN / CrMoN nanolayered composite coatings deposited at different rotation speeds within a vacuum chamber. Figures 11-14 The three-dimensional wear track morphology of AlCrSiWN / CrMoN nanolayered composite coatings deposited at different rotational speeds within a vacuum chamber is shown. At a rotational speed of 0.6 r / min, the coating's elastic modulus is at its lowest level. During friction, surface particles undergo significant plastic deformation and detach, becoming wear debris and contributing to the friction, resulting in deeper grooves and adhesions in the wear track, thus increasing the friction coefficient. Three-dimensional morphology analysis shows that although the groove depth is large at this speed, the number is small, resulting in a low overall wear rate. When the rotational speed increases to 0.9 r / min, the number and depth of grooves in the wear track increase, leading to a higher material removal rate and a corresponding increase in wear rate. At 1.2 r / min, the coating hardness and H³ / E... *2 The values ​​all reached their peak values, and the combination of high hardness and good toughness effectively suppressed crack propagation and brittle spalling, resulting in a narrowing of the wear track width. At this point, only a few deep furrows could be observed at surface defects, without numerous shallow spalling marks. Further increasing the rotational speed to 1.5 r / min revealed a large amount of oxide adhesion inside and at the edges of the wear tracks. Under cyclic frictional loading, when the local contact stress exceeds the material's fatigue limit, it causes the spalling of granular or flaky wear debris, forming obvious spalling pits.

[0080] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. An AlCrSiWN / CrMoN nanomultilayer composite coating with high hardness and self-lubricating performance, characterized in that: The multilayer composite coating is deposited on the surface of a cemented carbide substrate, and is a modulation coating formed by alternately depositing an AlCrSiWN high-hardness layer and a CrMoN self-lubricating layer; The total thickness of the multilayer composite coating is 3-4 μm, and the period thickness is 0.011-0.038 μm; the microstructure of the AlCrSiWN / CrMoN nanometer multilayer composite coating comprises hcp-Cr2N, fcc-CrN, h-(Cr,W)N2, h-W2N, t-Mo2N and c-WN phases; The modulation ratio of the multilayer composite coating is 2:1-1:2, and the modulation ratio refers to the thickness ratio of the AlCrSiWN high-hardness layer to the CrMoN self-lubricating layer; The AlCrSiWN / CrMoN nanometer multilayer composite coating has a chemical composition of 6.74-8.73 at.% of Al, 33.74-35.59 at.% of Cr, 6.36-8.13 at.% of Mo, 1.71-2.69 at.% of Si, 1.06-1.98 at.% of W and 46.17-48.76 at.% of N in terms of atomic percentage; An AlCrN transition layer is deposited between the multilayer composite coating and the substrate, and the AlCrN transition layer has a columnar crystal structure and a thickness of 100-120 nm.

2. The AlCrSiWN / CrMoN nanomultilayer composite coating with high hardness and self-lubricating performance according to claim 1, characterized in that: The hardness of the AlCrSiWN / CrMoN nanomultilayer composite coating can reach 43.42 GPa, the elastic modulus can reach 467.88 GPa, H / E and H 3 / E *2 can respectively reach 0.097 and 0.31 GPa. 3.The AlCrSiWN / CrMoN nanomultilayer composite coating with high hardness and self-lubricating performance according to claim 1, characterized in that: The friction coefficient and wear rate of the AlCrSiWN / CrMoN nanomultilayer composite coating are respectively as low as 0.44 and 1.68*10 -10 mm 3 / (N·mm).

4. The process for preparing AlCrSiWN / CrMoN nanomultilayer composite coating with high hardness and self-lubricating performance according to any one of claims 1-3, characterized in that: The process is an arc ion plating process, in which an AlCrN transition layer is first deposited on the substrate, and then an AlCrSiWN high-hardness layer and a CrMoN self-lubricating layer are alternately deposited to obtain an AlCrSiWN / CrMoN nanometer multilayer composite coating.

5. The preparation process of AlCrSiWN / CrMoN nanomultilayer composite coating with high hardness and self-lubricating performance according to claim 4, characterized in that: When the AlCrSiWN / CrMoN nanometer multilayer composite coating is deposited, N2 is introduced into the vacuum coating chamber, and the AlCrSiW target and the CrMo target are turned on, the rotation speed of the rotating shaft in the vacuum coating chamber is controlled, the AlCrSiWN high-hardness layer and the CrMoN self-lubricating layer are alternately deposited, and finally the multilayer composite coating is obtained; During the deposition process, the vacuum degree is controlled to be 3×10 -3 The deposition temperature is 400-500 ℃, and the rotating speed of the rotating shaft is 0.5 r / min~1.5 r / min.

6. The process for preparing AlCrSiWN / CrMoN nanomultilayer composite coating with high hardness and self-lubricating performance according to claim 5, characterized in that: The process specifically comprises the following steps: (1) The substrate is ultrasonically cleaned and dried, then fixed on a sample clamp, and hung on a rotating shaft in a coating chamber to ensure that the substrate faces the coating target; (2) The plating chamber is vacuumed to a vacuum degree of 3.0*10 -3 Pa or above, and the temperature in the vacuum plating chamber is heated to 400-500 ℃ and kept for 30 min. (3) Etching cleaning: turn on the etching Ti target, and etch clean the substrate in an Ar atmosphere; (4) Depositing an AlCrN transition layer: introduce N2, and turn on the AlCr target, and the deposition time is 30-35 min; (5) Depositing an AlCrSiWN / CrMoN nanometer multilayer film: adjust the N2 flow to 1260-1390 sccm, turn on the AlCrSiW target and the CrMo target, control the AlCrSiW target current to be 120-160 A and the CrMo target current to be 120-150 A, and the total deposition time is 100-130 min, to obtain an AlCrSiWN / CrMoN nanometer multilayer film in which an AlCrSiWN high-hardness layer and a CrMoN self-lubricating layer are alternately arranged.

7. The process for preparing AlCrSiWN / CrMoN nanomultilayer composite coating with high hardness and self-lubricating performance according to claim 6, characterized in that: In step (3), the etching cleaning process is as follows: after heating and constant temperature for 30 min in the vacuum coating chamber, Ar is introduced at a flow rate of 150-300 sccm, the deposition pressure is controlled to be 0.26-0.35 Pa, the Ti target is opened for etching, the Ti target arc source current is 120-140 A, the direct current bias is set to be increased from-10 V to-180 V at a gradient, and the etching cleaning time is 60-90 min.

8. The process for preparing AlCrSiWN / CrMoN nanomultilayer composite coating with high hardness and self-lubricating performance according to claim 6, characterized in that: In step (4), after etching cleaning, an AlCrN transition layer is deposited, and during the deposition process, N2 is introduced at a flow rate of 1220-1280 sccm, the deposition pressure is 3.2-4.5 Pa, the AlCr target current is 120-140 A, and the direct current bias is-40--60 V.

9. The process for preparing AlCrSiWN / CrMoN nanomultilayer composite coating with high hardness and self-lubricating performance according to claim 6, characterized in that: In step (5), when the AlCrSiWN / CrMoN nanometer multilayer film is deposited, the AlCrSiW target arc source current is 130-155 A, the CrMo target arc source current is 130-145 A, the rotating shaft rotating speed is 0.6-1.3 r / min, the deposition pressure is 3.5-4 Pa, and the direct current bias is-120--160 V.

10. The process for preparing AlCrSiWN / CrMoN nanomultilayer composite coating with high hardness and self-lubricating performance according to claim 6 or 9, characterized in that: In step (5), when the AlCrSiWN / CrMoN nanometer multilayer film is deposited, with the increase of the rotating shaft rotating speed, the diffraction peak intensity of the fcc-CrN phase (220) and the c-WN phase (311) in the obtained nanometer multilayer composite coating gradually increases.

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