A WS2-based composite coating and its preparation method

Abstract

The application belongs to the field of preparation of magnetron sputtering coating, and particularly relates to a WS2-based composite coating and a preparation method thereof. The method is a magnetron sputtering method, wherein a Cr transition layer is first sputtered on a substrate, then a WS2 target radio frequency power supply and a Cr target direct current power supply are turned on, the WS2 target sputtering power is controlled to be 110-150 W, the Cr target sputtering power is controlled to be 15-20 W, the WS2-Cr composite coating is obtained by co-sputtering on the Cr transition layer for 30±10 min, the WS2 target sputtering power is controlled to be 180-190 W, the Cu target sputtering power is controlled to be 10-20 W, and the WS2-Cu composite coating is obtained by co-sputtering on the WS2-Cr composite coating for 60±10 min. The application realizes effective cooperation of high bearing of the WS2-Cr composite coating and high lubrication of the WS2-Cu composite coating, and effectively improves the lubrication life of the coating under high bearing working conditions.

Description

Technical Field

[0001] This invention belongs to the field of magnetron sputtering coating preparation, specifically relating to a WS2-based composite coating and its preparation method. Background Technology

[0002] Molybdenum disulfide (MoS2) has a typical layered hexagonal crystal structure, which readily undergoes interlayer slip during friction, forming an effective lubrication transfer film on the contact surface and significantly reducing friction and wear. It is commonly used for lubrication of space equipment. However, it is highly susceptible to oxidation in high humidity and high temperature environments, forming hard abrasive particles (MoO3), leading to lubrication failure and limiting its multi-environment applications. In recent years, WS2, with a similar structure to MoS2, has shown superior multi-environment lubrication potential due to its higher oxidation temperature and the fact that its oxidation product, WO3, still possesses some lubricity.

[0003] However, the lubrication life of traditional pure WS2 coatings still faces serious challenges in practical applications, especially under high load and long-cycle operation conditions. This is mainly due to its insufficient intrinsic mechanical properties and its generally loose microstructure. During continuous friction, the lubricating phase is consumed at a relatively fast rate, and the wear debris generated by wear is difficult to effectively contain, which easily leads to the aggravation of abrasive wear and causes premature lubrication failure.

[0004] To overcome the aforementioned shortcomings, the industry has explored various technical approaches for modification. Among these, elemental doping (such as co-deposition with hard materials like titanium, chromium, and boron) is a common method. By introducing dopant elements, the grain size of WS2 can be refined to some extent, improving the coating's density, hardness, and tribological properties. However, these improvements are highly dependent on the doping content; too low a doping content offers limited improvement in mechanical properties, while excessive doping reduces the lubrication capacity of WS2. Therefore, doping modification often involves trade-offs between different performance indicators, making it difficult to achieve synergistic high load-bearing capacity, excellent lubrication durability, and superior film-substrate adhesion in a single coating. Under complex and varied tribological conditions, the performance limitations of a single composite structure will still be exposed, restricting further improvements in the overall service life of the coating.

[0005] Chinese invention patent application CN 118639198 A, published on September 13, 2024, discloses a nanocomposite / multilayer tungsten disulfide-based thin film and its preparation method. The method utilizes WS2-Au target radio frequency sputtering to deposit a WS2-Au composite layer and a Ti thin layer to deposit a Ti thin layer using a Ti target DC sputtering. The WS2-Au composite layer and the Ti layer are deposited periodically and alternately. The thickness of the WS2-Au composite layer is controlled to be 50~150nm, and the thickness of the Ti thin layer is controlled to be 3~20nm. After 6~7 modulation cycles, a nanocomposite / multilayer tungsten disulfide-based thin film is obtained.

[0006] Chinese invention patent application CN 114574826 A, published on June 3, 2022, discloses a molybdenum disulfide / copper composite thin film. The film is prepared by sequentially depositing a titanium transition layer, a titanium / copper / molybdenum disulfide gradient transition layer, and a molybdenum disulfide / copper doped layer on a substrate surface, followed by a sulfidation treatment. The titanium / copper / molybdenum disulfide gradient transition layer is achieved by controlling the target current on the titanium target to gradually decrease, while the target currents on the molybdenum disulfide and copper targets to gradually increase, resulting in a transition layer with gradually decreasing titanium content and gradually increasing molybdenum disulfide and copper content.

[0007] The tribological performance tests of the aforementioned disulfide lubricating coatings were conducted under normal loads of 3 to 5 N. The coatings were designed based on general load conditions. Under high load conditions, the lubrication structure of the coatings will be rapidly damaged, resulting in a short wear life. Summary of the Invention

[0008] The purpose of this invention is to provide a method for preparing a WS2-based composite coating to solve the problem of short wear life of existing tungsten disulfide lubricating coatings under high load conditions.

[0009] The second objective of this invention is to provide a WS2-based composite coating prepared by the above-mentioned method, in order to solve the problem that existing molybdenum disulfide lubricating coatings cannot simultaneously achieve high load-bearing capacity and long-life lubrication.

[0010] To achieve the above objectives, the technical solution adopted by this invention is as follows: A method for preparing a WS2-based composite coating includes the following steps: First, a Cr transition layer is sputtered onto a substrate using magnetron sputtering. Then, the WS2 target RF power supply and the Cr target DC power supply are turned on, controlling the WS2 target sputtering power to be 110~150W and the Cr target sputtering power to be 15~20W. The WS2 target is sputtered for a total of 30±10 min to obtain the WS2-Cr composite coating. Finally, the Cr target DC power supply is turned off and the Cu target DC power supply is turned on, controlling the WS2 target sputtering power to be 180~190W and the Cu target sputtering power to be 10~20W. The WS2-Cr composite coating is sputtered for a total of 60±10 min to obtain the WS2-Cu composite coating.

[0011] This invention improves the load-bearing capacity of the WS2 coating by doping with a high Cr content and improves the lubrication performance of the WS2 coating by doping with Cu. At the same time, the deposition time of the WS2-Cr composite coating and the WS2-Cu composite coating are controlled within a suitable range. The high load-bearing capacity of the WS2-Cr composite coating and the high lubrication of the WS2-Cu composite coating work together effectively to improve the lubrication life of the coating under high load conditions.

[0012] Experiments have shown that improper deposition time of WS2-Cr and WS2-Cu composite coatings will make it difficult to guarantee the overall structure of the coating under high load conditions, resulting in a sharp reduction in wear life. This indicates that precise control is needed for the deposition of WS2-Cr and WS2-Cu composite coatings to ensure long-term lubrication under high load conditions.

[0013] Furthermore, unlike existing technologies that prepare smooth and uniform copper-doped molybdenum disulfide layers, the WS2-Cu composite coating obtained using this method has a uniformly deposited WS2-Cu layer bonded to the WS2-Cr composite coating, and WS2-Cu columnar particles are also dispersed on the uniformly deposited WS2-Cu layer. This non-uniform morphology coating exhibits high hardness and a low coefficient of friction, ensuring long-life lubrication of the coating.

[0014] Preferably, when co-sputtering the WS2-Cr composite coating and the WS2-Cu composite coating, the working gas is argon, with an argon flow rate of 40~60 sccm and a sputtering pressure of 1.0~1.2 Pa. Using argon co-sputtering and controlling the argon flow rate and sputtering pressure within the above ranges can effectively ensure the uniform and stable sputtering quality of the WS2-Cr and WS2-Cu composite coatings.

[0015] More preferably, during the co-sputtering of the WS2-Cr composite coating and the WS2-Cu composite coating, the argon flow rate and sputtering pressure are kept constant, with the argon flow rate being 40~50 sccm and the sputtering pressure being 1.0~1.1 Pa. Maintaining constant argon flow rate and sputtering pressure during the co-sputtering of the WS2-Cr composite coating and the WS2-Cu composite coating ensures consistent sputtering conditions and guarantees good interfacial bonding quality between the two coatings.

[0016] Preferably, when co-sputtering the WS2-Cr composite coating, the sputtering power of the WS2 target is 110~150W, and the sputtering power of the Cr target is 15~18W. Controlling these conditions during the co-sputtering of the WS2-Cr composite coating can ensure an appropriate amount of Cr doping, thus guaranteeing the strength and toughness of the WS2-Cr composite coating.

[0017] More preferably, when co-sputtering the WS2-Cu composite coating, the sputtering power of the WS2 target is 190 W, and the sputtering power of the Cu target is 10~15 W. By controlling these conditions during the co-sputtering of the WS2-Cu composite coating, the Cu doping amount can reach 10 at.%~20 at.%, ensuring interfacial bonding with the WS2-Cr composite coating. At the same time, the WS2-Cu composite coating itself has high hardness and elastic modulus, effectively improving the wear resistance life of the coating.

[0018] Preferably, when sputtering the Cr transition layer, the Cr target is connected to a DC power supply, the Cr target sputtering power is 70~90W, the argon flow rate is 40~60 sccm, the sputtering pressure is 0.6~1.2Pa, and the deposition time is 15~20min. By controlling the above sputtering process parameters, a Cr transition layer with good adhesion to the substrate can be obtained at a relatively thin thickness.

[0019] Preferably, the substrate undergoes plasma cleaning before sputtering the Cr transition layer, and during plasma cleaning, the gas pressure in the coating chamber is evacuated to no more than 5.0 × 10⁻⁶. -4 The pressure is set at Pa, then argon gas is introduced at a flow rate of 70-90 sccm, the chamber pressure is 0.5-2.0 Pa, and the substrate temperature is 100-300℃. Plasma cleaning effectively removes residual impurities and contaminants from the substrate surface, placing it in an active bonding state.

[0020] Preferably, the thickness of the Cr transition layer is 0.1~0.3μm; the thickness of the WS2-Cr composite coating is 0.2~0.5μm; and the thickness of the WS2-Cu composite coating is 2~6μm. Controlling the thickness of the Cr transition layer, WS2-Cr composite coating, and WS2-Cu composite coating within the above-mentioned thickness range will not cause significant changes to the dimensions of the workpiece, and will maximize the load-bearing and lubrication performance of the workpiece within a reasonable thickness range.

[0021] More preferably, the thickness of the Cr transition layer is 0.1~0.2μm; the thickness of the WS2-Cr composite coating is 0.2~0.4μm; and the thickness of the WS2-Cu composite coating is 3~4μm. Controlling the thicknesses of the Cr transition layer, WS2-Cr composite coating, and WS2-Cu composite coating within the above-mentioned ranges effectively improves the service life of the coating while maintaining a relatively thin total coating thickness.

[0022] A WS2-based composite coating prepared using the above-mentioned method for preparing WS2-based composite coatings.

[0023] The WS2-based composite coating prepared by the above method breaks through the bottleneck of existing single-structure coatings in long-term lubrication. It comprehensively regulates its mechanical load-bearing performance and lubrication function characteristics, and synergistically achieves high load-bearing capacity, excellent lubrication durability and excellent film-substrate adhesion, effectively improving the overall service life of the coating under heavy load conditions.

[0024] Compared with the prior art, the present invention achieves the following beneficial effects: 1. This invention uses unbalanced magnetron sputtering technology to prepare a double-layer WS2 coating with different doping, which has a lubrication life much greater than that of a single-layer doped coating.

[0025] 2. The Cr transition layer, WS2-Cr carrier layer, and WS2-Cu lubricating layer are all prepared using magnetron sputtering technology. This process offers a high degree of continuity, and the specific sputtering process control is simple, making it suitable for industrial production. Controlling the deposition time of the WS2-Cr carrier layer to approximately half that of the WS2-Cu lubricating layer achieves a better synergy between mechanical load-bearing and lubrication properties, facilitating the fabrication of long-life, multilayer tungsten disulfide lubricating coatings.

[0026] 3. The hardness and elastic modulus of the multilayer WS2 base coating are 6~8GPa and 85~110GPa, respectively, and the wear resistance life is greater than 18h, which is several times higher than that of the prepared WS2-Cr coating and WS2-Cu coating. Attached Figure Description

[0027] Figure 1 SEM image of the monolayer WS2-Cu functional coating in Comparative Example 4; Figure 2 SEM image of the single-layer WS2-Cr functional coating of Comparative Example 3; Figure 3 This is a SEM image of the WS2-based composite coating of Embodiment 1 of the present invention; Figure 4 The friction curves are of the coatings in Example 1, Comparative Examples 3 and 4 of the present invention. Detailed Implementation

[0028] (I) Preferred embodiments of the WS2-based composite coating and its preparation method of the present invention This invention discloses a long-life, multilayer WS2-based coating prepared by unbalanced magnetron sputtering. The coating consists of a Cr transition layer, a WS2-Cr carrier layer composited on the Cr transition layer, and a WS2-Cu lubricating layer. By precisely controlling the sputtering power and deposition time of the WS2-Cr carrier layer and the WS2-Cu lubricating layer, the WS2-Cr carrier layer can maintain its strong structure under heavy loads and continuous friction, while reducing structural damage to the WS2-Cu lubricating layer, thus achieving long-term lubrication under high-load conditions.

[0029] Both single WS2-Cr composite coatings and single WS2-Cu composite coatings have high hardness. The WS2-Cu composite coating prepared by the magnetron sputtering process of this invention also has a low average coefficient of friction. However, the wear life of both single WS2-Cr composite coatings and single WS2-Cu composite coatings is relatively short, reflecting that it is difficult to improve the overall wear resistance of the coating by organically combining the WS2-Cr composite coating and the WS2-Cu composite coating.

[0030] In the continuous friction process under high load conditions, in addition to having a high-performance contact lubrication layer, improving the overall load-bearing capacity of the coating is also crucial. During the above process, the coating needs to withstand complex stresses such as heavy loads and sliding shear, which places high demands on the overall toughness, crack suppression ability, and energy dissipation characteristics of the coating. Incompatible coating structure design can lead to catastrophic early peeling or rapid wear-through of the coating.

[0031] Rigorous comparative experiments revealed that, under appropriate WS2 RF sputtering power and Cr and Cu DC sputtering power, the WS2-Cr co-sputtering time is about half that of the WS2-Cu co-sputtering time to achieve the above-mentioned high load-bearing and long-lasting lubrication requirements. Under other conditions, the wear resistance life is greatly limited.

[0032] The preparation method of the above-mentioned WS2-based composite coating specifically adopts the following implementation steps: (1) Substrate pretreatment This step involves grinding, polishing, and solvent cleaning of the substrate to prepare it for subsequent magnetron sputtering. The substrate can be a metal substrate, monocrystalline silicon, etc. Metal substrates include GCr15 bearing steel and 304 stainless steel.

[0033] Solvent cleaning can be performed using solvents such as ethanol and acetone. Ultrasonic assistance can be further used to thoroughly clean the substrate surface, followed by drying with an inert gas such as nitrogen.

[0034] (2) Plasma cleaning of substrate after pretreatment This step involves plasma cleaning of the pretreated substrate to further remove residual impurities and contaminants from its surface. Plasma cleaning activates the metal substrate surface, facilitating bonding with subsequent coatings.

[0035] Specifically, the air pressure in the coating chamber is evacuated to no more than 5 × 10⁻⁶. -4 Pa, then argon gas is introduced, with the Ar gas flow rate controlled at 70~90 sccm, the chamber pressure stabilized at 0.5~2.0 Pa, and the substrate temperature at 100~300℃. The cleaning power supply is DC, with the sputtering power controlled at 30~50W, and the processing time at 15~20min.

[0036] More preferably, the Ar gas flow rate during plasma cleaning is 70~80 sccm, the chamber gas pressure is stabilized at 1.0~1.2 Pa, and the substrate temperature is 200~300℃.

[0037] (3) Preparation of Cr transition layer This step uses argon as the sputtering gas and a Cr target as the sputtering target. The Cr target is powered by a DC power supply. The sputtering power of the Cr target is controlled at 70~90W, the argon flow rate is 40~60 sccm, the sputtering pressure is 0.6~1.2Pa, and the deposition time is 15~20min to prepare the Cr transition layer.

[0038] More preferably, the Cr target sputtering power is 70-80 W, the argon flow rate is 40-50 sccm, and the sputtering pressure is 0.6-1.0 Pa. A Cr transition layer with a thickness of 0.1-0.3 μm is prepared. The typical thickness of the Cr transition layer can be 0.1-0.15 μm or 0.15-0.2 μm, etc.

[0039] (4) Preparation of WS2-Cr composite coating by co-sputtering This step involves simultaneously turning on the WS2 target RF power supply and the Cr target DC power supply, gradually increasing the WS2 target power while gradually decreasing the Cr target power to the required deposition power, and co-sputtering to prepare the WS2-Cr composite coating.

[0040] Specifically, the sputtering power of the Cr target is 15~20W; the sputtering power of the WS2 target is 110~150W; the argon flow rate is 40~60sccm; the sputtering pressure is 0.5~1.2Pa; and the deposition time is 30±10min.

[0041] More preferably, the sputtering power of the Cr target is 15~20W; the sputtering power of the WS2 target is 110~150W; the argon flow rate is 40~50sccm; the sputtering pressure is 1.0~1.2Pa; and the deposition time is 30±5min, more preferably 30±2min.

[0042] The rate at which the WS2 target power is gradually increased can be 60~80 W / min; the rate at which the Cr target power is gradually decreased can be 30~40 W / min.

[0043] (5) Preparation of WS2-Cu composite coating by co-sputtering This step involves switching the DC power supply target from Cr to Cu, adjusting the WS2 and Cu power to the required deposition power, and co-sputtering to prepare the WS2-Cu composite coating.

[0044] The sputtering power of the Cu target is 10~20W; the sputtering power of the WS2 target is 180~190W, supplied by an RF power supply; the argon flow rate is 40~60sccm; the sputtering pressure is 1.0~1.2Pa; and the deposition time is 60±10min.

[0045] More preferably, the Cu target sputtering power is 10~15W; the WS2 target is supplied by an RF power supply with a sputtering power of 190W; the argon flow rate and sputtering pressure are kept constant; the deposition time is 60±5min, more preferably 60±3min.

[0046] The WS2-based composite coatings prepared using the above method have a Cr transition layer thickness of 0.1–0.3 μm, a WS2-Cr composite coating thickness of 0.2–0.5 μm, and a WS2-Cu composite coating thickness of 2–6 μm. The hardness reaches 6–8 GPa, and the elastic modulus reaches 85–110 GPa. Under the same conditions, the high load-bearing lubrication life is several to tens of times that of single WS2-Cr and WS2-Cu functional coatings.

[0047] The preferred embodiments of the present invention are illustrated below with reference to specific examples. Unless otherwise specified, the raw materials and processing techniques involved are all prior art. The metal substrate is GCr15 bearing steel. The purpose of the GCr15 bearing steel substrate is to facilitate the testing of the hardness and tribological properties of the thin film, and the purpose of the single-crystal silicon wafer is to facilitate the characterization of the microstructure of the thin film.

[0048] Example 1 The preparation method of the WS2-based composite coating in this embodiment adopts the following steps: The metal substrate was first polished using a precision grinding and polishing machine with sandpaper of different roughness; then, the metal substrate and the single-crystal silicon wafer were ultrasonically cleaned with analytical grade ethanol and acetone for 20 minutes respectively, dried with nitrogen, and then placed in a vacuum coating chamber; the air pressure in the coating chamber was evacuated to 5 × 10⁻⁶. -4The process begins with argon gas being introduced at a flow rate of 70 sccm, the chamber pressure stabilized at 1.0 Pa, and the substrate heating temperature adjusted to 300℃. Plasma cleaning of the substrate is then performed for 15 min. Subsequently, the argon flow rate is adjusted to 40 sccm, the sputtering pressure to 0.6 Pa, the Cr target sputtering power to 70 W, and the deposition time to 15 min, yielding a Cr transition layer of approximately 150 nm. The pressure is then adjusted to 1.0 Pa, and the Cr target power is reduced to 15 W at a rate of 30 W / min, while the WS2 target power is increased from 0 W to 150 W at a rate of 80 W / min. This power is maintained for 30 min after the target power stabilizes. Then, maintaining the gas flow rate and deposition pressure constant, the Cr target is turned off, the Cu target is turned on, and the Cu target power is increased to 15 W at a rate of 30 W / min, while the WS2 target power is increased from 150 W to 190 W at a rate of 80 W / min. This power is maintained for 60 min after the target power stabilizes.

[0049] The WS2-based composite coating of this embodiment is prepared by the method of this embodiment and consists of a metal substrate and a Cr transition layer, a WS2-Cr composite coating and a WS2-Cu composite coating sequentially laminated on the metal substrate from the inside to the outside; the thicknesses of the Cr transition layer, the WS2-Cr composite coating and the WS2-Cu composite coating are approximately 150 nm, 0.30 μm and 3.45 μm, respectively.

[0050] Example 2 The preparation method of the WS2-based composite coating in this embodiment adopts the following steps: The metal substrate was first polished using a precision grinding and polishing machine with sandpaper of different roughness; then, the metal substrate and the single-crystal silicon wafer were ultrasonically cleaned with analytical grade ethanol and acetone for 20 minutes respectively, dried with nitrogen, and then placed in a vacuum coating chamber; the air pressure in the coating chamber was evacuated to 5 × 10⁻⁶. -4 The process begins with argon gas being introduced at a flow rate of 70 sccm, the chamber pressure stabilized at 1.0 Pa, and the substrate heating temperature adjusted to 300℃. Plasma cleaning of the substrate is then performed for 15 min. Subsequently, the argon flow rate is adjusted to 40 sccm, the sputtering pressure to 0.6 Pa, the Cr target sputtering power to 70 W, and the deposition time to 15 min, yielding a Cr transition layer of approximately 150 nm. The pressure is then adjusted to 1.0 Pa, and the Cr target power is reduced to 15 W at a rate of 30 W / min, while the WS2 target power is increased from 0 W to 150 W at a rate of 80 W / min. This power is maintained for 30 min after the target power stabilizes. Then, maintaining the gas flow rate and deposition pressure constant, the Cr target is turned off, the Cu target is turned on, and the Cu target power is increased to 10 W at a rate of 30 W / min, while the WS2 target power is increased from 150 W to 190 W at a rate of 80 W / min. This power is maintained for 60 min after the target power stabilizes.

[0051] The WS2-based composite coating of this embodiment is prepared by the method of this embodiment and consists of a metal substrate and a Cr transition layer, a WS2-Cr composite coating and a WS2-Cu composite coating sequentially laminated on the metal substrate from the inside to the outside; the thicknesses of the Cr transition layer, the WS2-Cr composite coating and the WS2-Cu composite coating are approximately 150 nm, 0.30 μm and 3.25 μm, respectively.

[0052] Example 3 The preparation method of the WS2-based composite coating in this embodiment adopts the following steps: The metal substrate was first polished using a precision grinding and polishing machine with sandpaper of different roughness; then, the metal substrate and the single-crystal silicon wafer were ultrasonically cleaned with analytical grade ethanol and acetone for 20 minutes respectively, dried with nitrogen, and then placed in a vacuum coating chamber; the air pressure in the coating chamber was evacuated to 5 × 10⁻⁶. -4 The process begins with argon gas being introduced at a flow rate of 70 sccm, the chamber pressure stabilized at 1.0 Pa, and the substrate heating temperature adjusted to 300℃. Plasma cleaning of the substrate is then performed for 15 min. Subsequently, the argon flow rate is adjusted to 40 sccm, the sputtering pressure to 0.6 Pa, the Cr target sputtering power to 70 W, and the deposition time to 15 min, yielding a Cr transition layer of approximately 150 nm. The pressure is then adjusted to 1.0 Pa, and the Cr target power is reduced to 15 W at a rate of 30 W / min, while the WS2 target power is increased from 0 W to 110 W at a rate of 60 W / min. This power is maintained for 30 min after the target power stabilizes. Then, maintaining the gas flow rate and deposition pressure constant, the Cr target is turned off, the Cu target is turned on, and the Cu target power is increased to 15 W at a rate of 30 W / min, while the WS2 target power is increased from 110 W to 190 W at a rate of 80 W / min. This power is maintained for 60 min after the target power stabilizes.

[0053] The WS2-based composite coating of this embodiment is prepared by the method of this embodiment and consists of a metal substrate and a Cr transition layer, a WS2-Cr composite coating and a WS2-Cu composite coating sequentially composited on the metal substrate from the inside to the outside; the thicknesses of the Cr transition layer, the WS2-Cr composite coating and the WS2-Cu composite coating are approximately 150 nm, 0.23 μm and 3.42 μm, respectively.

[0054] Comparative Example 1 The preparation method of the WS2-based composite coating in this embodiment adopts the following steps: The metal substrate was first polished using a precision grinding and polishing machine with sandpaper of different roughness; then, the metal substrate and the single-crystal silicon wafer were ultrasonically cleaned with analytical grade ethanol and acetone for 20 minutes respectively, dried with nitrogen, and then placed in a vacuum coating chamber; the air pressure in the coating chamber was evacuated to 5 × 10⁻⁶. -4The process begins with argon gas being introduced at a flow rate of 70 sccm, the chamber pressure stabilized at 1.0 Pa, and the substrate heating temperature adjusted to 300℃. Plasma cleaning of the substrate is then performed for 15 min. Subsequently, the argon flow rate is adjusted to 40 sccm, the sputtering pressure to 0.6 Pa, the Cr target sputtering power to 70 W, and the deposition time to 15 min, yielding a Cr transition layer of approximately 150 nm. The pressure is then adjusted to 1.0 Pa, and the Cr target power is reduced to 15 W at a rate of 30 W / min, while the WS2 target power is increased from 0 W to 110 W at a rate of 60 W / min. This power is maintained for 30 min after the target power stabilizes. Then, maintaining the gas flow rate and deposition pressure constant, the Cr target is turned off, the Cu target is turned on, and the Cu target power is increased to 10 W at a rate of 30 W / min, while the WS2 target power is increased from 110 W to 190 W at a rate of 80 W / min. This power is maintained for 75 min after the target power stabilizes.

[0055] The WS2-based composite coating of this comparative example consists of a metal substrate and a Cr transition layer, a WS2-Cr composite coating, and a WS2-Cu composite coating sequentially laminated onto the metal substrate from the inside out; the thicknesses of the Cr transition layer, the WS2-Cr composite coating, and the WS2-Cu composite coating are approximately 150 nm, 0.22 μm, and 4.33 μm, respectively.

[0056] Comparative Example 2 The preparation method of the WS2-based composite coating in this embodiment adopts the following steps: The metal substrate was first polished using a precision grinding and polishing machine with sandpaper of different roughness; then, the metal substrate and the single-crystal silicon wafer were ultrasonically cleaned with analytical grade ethanol and acetone for 20 minutes respectively, dried with nitrogen, and then placed in a vacuum coating chamber; the air pressure in the coating chamber was evacuated to 5 × 10⁻⁶. -4 The process begins with argon gas being introduced at a flow rate of 70 sccm, the chamber pressure stabilized at 1.0 Pa, and the substrate heating temperature adjusted to 300℃. Plasma cleaning of the substrate is then performed for 15 min. Subsequently, the argon flow rate is adjusted to 40 sccm, the sputtering pressure to 0.6 Pa, the Cr target sputtering power to 70 W, and the deposition time to 15 min, yielding a Cr transition layer of approximately 150 nm. The pressure is then adjusted to 1.0 Pa, and the Cr target power is reduced to 15 W at a rate of 30 W / min, while the WS2 target power is increased from 0 W to 150 W at a rate of 60 W / min. This power is maintained for 60 min after the target power stabilizes. Then, maintaining the gas flow rate and deposition pressure constant, the Cr target is turned off, the Cu target is turned on, and the Cu target power is increased to 15 W at a rate of 30 W / min, while the WS2 target power is increased from 150 W to 190 W at a rate of 80 W / min. This power is maintained for 60 min after the target power stabilizes.

[0057] The WS2-based composite coating of this comparative example consists of a metal substrate and a Cr transition layer, a WS2-Cr composite coating, and a WS2-Cu composite coating sequentially laminated onto the metal substrate from the inside out; the thicknesses of the Cr transition layer, the WS2-Cr composite coating, and the WS2-Cu composite coating are approximately 150 nm, 0.59 μm, and 3.26 μm, respectively.

[0058] Comparative Example 3 The preparation method of the WS2-based composite coating in this embodiment adopts the following steps: The metal substrate was first polished using a precision grinding and polishing machine with sandpaper of different roughness; then, the metal substrate and the single-crystal silicon wafer were ultrasonically cleaned with analytical grade ethanol and acetone for 20 minutes respectively, dried with nitrogen, and then placed in a vacuum coating chamber; the air pressure in the coating chamber was evacuated to 5 × 10⁻⁶. -4 Pa, then argon working gas was introduced at a flow rate of 70 sccm, the pressure in the control chamber was stabilized at 1.0 Pa, the substrate heating temperature was adjusted to 300℃, and the substrate was plasma cleaned for 15 min; then the argon flow rate was adjusted to 40 sccm, the sputtering pressure was 0.6 Pa, the Cr target sputtering power was adjusted to 70 W, and the deposition time was 15 min, to prepare a Cr transition layer of about 150 nm; then the pressure was adjusted to 1.0 Pa, the Cr target power was reduced to 15 W at a rate of 30 W / min, and the WS2 target power was adjusted from 0 W to 150 W at a rate of 60 W / min, and maintained for 60 min after the target power stabilized.

[0059] The WS2-based composite coating of this comparative example consists of a metal substrate, a Cr transition layer sequentially laminated on the metal substrate from the inside out, and a WS2-Cr composite coating; the thickness of the Cr transition layer is approximately 150 nm, and the total coating thickness is approximately 0.7 μm.

[0060] Comparative Example 4 The preparation method of the WS2-based composite coating in this embodiment adopts the following steps: The metal substrate was first polished using a precision grinding and polishing machine with sandpaper of different roughness; then, the metal substrate and the single-crystal silicon wafer were ultrasonically cleaned with analytical grade ethanol and acetone for 20 minutes respectively, dried with nitrogen, and then placed in a vacuum coating chamber; the air pressure in the coating chamber was evacuated to 5 × 10⁻⁶. -4Pa, then argon working gas was introduced at a flow rate of 70 sccm, the pressure in the control chamber was stabilized at 1.0 Pa, the substrate heating temperature was adjusted to 300℃, and the substrate was plasma cleaned for 15 min; then the argon flow rate was adjusted to 40 sccm, the sputtering pressure was 0.6 Pa, the Cr target sputtering power was increased to 70 W, and the deposition time was 15 min, to prepare a Cr transition layer of about 150 nm; then the pressure was adjusted to 1.0 Pa, the Cr target was turned off, the Cu target was turned on, the Cu target power was increased to 15 W at a rate of 30 W / min, and the WS2 target was increased from 0 W to 190 W at a rate of 80 W / min, and maintained for 60 min after the target power stabilized.

[0061] The WS2-based composite coating of this comparative example consists of a metal substrate and a Cr transition layer and a WS2-Cu composite coating sequentially laminated on the metal substrate from the inside out; the thickness of the Cr transition layer is about 150 nm, and the total coating thickness is about 4.2 μm.

[0062] (II) Experimental Examples Experimental Example 1 High-resolution electron microscopy analysis was performed on the multilayer WS2 composite coating prepared in Example 1 of this invention, the single-layer WS2-Cr composite coating prepared in Comparative Example 3, and the WS2-Cu composite coating prepared in Comparative Example 4. The results are as follows: Figures 1-3 As shown.

[0063] Depend on Figures 1-3 It can be seen that the single-layer WS2-Cr composite coating (Cr-doped) is uniform and dense, while the single-layer WS2-Cu composite coating (Cu-doped) mainly consists of two layers: one layer is uniform and dense, and the other layer has a large number of columnar particles (mainly Cu). The cross-sectional morphology of the multilayer WS2 composite coating is consistent with the morphology of the two types of element doping.

[0064] Experiment Example 2 This experiment tested the hardness, average coefficient of friction, and wear life of the coatings obtained in each embodiment and comparative example. The hardness test was performed according to the following standard: GB / T 25898-2010 "Instrumented Nanoindentation Test Method - Indentation Hardness and Elastic Modulus of Thin Films". The performance test results of the coatings in each embodiment and comparative example are shown in Table 1.

[0065] During the friction coefficient test, an atmospheric friction and wear testing machine was used, employing a ball-disc contact reciprocating motion mode. The upper sample was a commercially available GCr15 steel ball with a diameter of 8 mm, and the lower sample was a coated flat steel specimen. The normal load was 10 N, the wear track length was 6 mm, and the motion frequency was 5 Hz. The friction coefficient curves of Example 1 and Comparative Examples 3 and 4 of this invention are shown below. Figure 4As shown. The wear life refers to the life during which the film no longer has a lubricating effect (judged by the change in the coefficient of friction; when the coefficient of friction is greater than 0.3, the film is considered to have worn out).

[0066] Table 1. Coating composition, thickness of each layer, coefficient of friction, and wear life.

[0067] From Table 1, Figure 4 The results show that the coatings in Examples 1-3 have low average friction coefficients and wear life exceeding 1100 min, which is significantly longer than that of single-layer WS2-Cr and WS2-Cu functional coatings. For the bilayer functional layer composed of WS2-Cr and WS2-Cu layers, the matching of deposition times for each layer is also crucial. Improper matching of deposition times will directly lead to the destruction of the lubrication structure of the final coating under high load conditions, resulting in a sharp reduction in wear life.

[0068] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a WS2-based composite coating, characterized in that, Includes the following steps: Using magnetron sputtering, a Cr transition layer was first sputtered onto the substrate. Then, the WS2 target RF power supply and the Cr target DC power supply were turned on, and the sputtering power of the WS2 target was controlled at 110~150W and the sputtering power of the Cr target was controlled at 15~20W. The Cr transition layer was sputtered for a total of 30±10min to obtain a WS2-Cr composite coating. Finally, the Cr target DC power supply was turned off and the Cu target DC power supply was turned on. The sputtering power of the WS2 target was controlled at 180~190W and the sputtering power of the Cu target was controlled at 10~20W. The WS2-Cr composite coating was sputtered for a total of 60±10min to obtain a WS2-Cu composite coating.

2. The method for preparing the WS2-based composite coating as described in claim 1, characterized in that, When co-sputtering WS2-Cr composite coating and WS2-Cu composite coating, the working gas is argon, and the argon flow rate is 40~60 sccm; the sputtering pressure is 1.0~1.2 Pa.

3. The method for preparing the WS2-based composite coating as described in claim 2, characterized in that, When co-sputtering WS2-Cr composite coating and WS2-Cu composite coating, the argon flow rate and sputtering pressure are kept constant, with the argon flow rate being 40~50 sccm and the sputtering pressure being 1.0~1.1 Pa.

4. The method for preparing the WS2-based composite coating as described in claim 1, characterized in that, When co-sputtering the WS2-Cr composite coating, the sputtering power of the WS2 target is 110~150W, and the sputtering power of the Cr target is 15~18W.

5. The method for preparing the WS2-based composite coating as described in claim 4, characterized in that, When co-sputtering the WS2-Cu composite coating, the sputtering power of the WS2 target is 190 W, and the sputtering power of the Cu target is 10~15 W.

6. The method for preparing the WS2-based composite coating as described in claim 1, characterized in that, When sputtering the Cr transition layer, the Cr target is connected to a DC power supply, the sputtering power of the Cr target is 70~90W, the argon flow rate is 40~60 sccm, the sputtering pressure is 0.6~1.2Pa, and the deposition time is 15~20min.

7. The method for preparing the WS2-based composite coating as described in claim 1, 4, or 6, characterized in that, Before sputtering the Cr transition layer onto the substrate, plasma cleaning is performed. During plasma cleaning, the gas pressure in the coating chamber is evacuated to no more than 5.0 × 10⁻⁶. -4 Pa, then argon gas is introduced, with an argon flow rate of 70~90 sccm, a chamber pressure of 0.5~2.0 Pa, and a base temperature of 100~300℃.

8. The method for preparing the WS2-based composite coating as described in claim 1, 4, or 6, characterized in that, The thickness of the Cr transition layer is 0.1~0.3μm; the thickness of the WS2-Cr composite coating is 0.2~0.5μm; and the thickness of the WS2-Cu composite coating is 2~6μm.

9. The method for preparing the WS2-based composite coating as described in claim 8, characterized in that, The thickness of the Cr transition layer is 0.1~0.2μm; the thickness of the WS2-Cr composite coating is 0.2~0.4μm; and the thickness of the WS2-Cu composite coating is 3~4μm.

10. A WS2-based composite coating prepared by the method of any one of claims 1 to 9.

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