Molybdenum disulfide / copper composite lubricating film and method for preparing the same

Abstract

The present application relates to a molybdenum disulfide / copper composite lubricating film and a preparation method thereof. The film material is composed of a titanium transition layer and a copper-doped molybdenum disulfide layer, and is prepared by using a magnetron sputtering technology. The sputtering gas is argon, and the sputtering target material is titanium, copper and molybdenum disulfide. Under suitable gas pressure and bias conditions, the molybdenum disulfide / copper composite film with uniform and dense structure, obvious preferred orientation, good electrical properties (static resistivity is about 15 mΩ·cm) and tribological properties is prepared by changing the opening of the baffle on the copper target. In the vacuum environment (<10 ‑3 Pa) with current load, the friction coefficient is about 0.039, the wear rate is about 1.31×10 ‑6 mm 3 / Nm, and the film shows good tribological properties. The molybdenum disulfide / copper composite lubricating film can be used for surface friction reduction and wear resistance treatment of electric contact sliding parts such as plug-in interfaces, conductive slip rings and the like in the fields of aerospace and semiconductor manufacturing.

Description

Technical Field

[0001] This invention belongs to the field of lubricant preparation technology, and particularly relates to a molybdenum disulfide / copper composite lubricating film and its preparation method. This composite lubricating film can be used in vacuum current-carrying conditions. Background Technology

[0002] With the increasing intelligence, miniaturization, and multifunctionality of space motion components in the aerospace field, single-function lubricating materials are severely limited in practical applications. For example, electrical contact components such as satellite conductive slip rings and plug-in interfaces involve the transmission of electrical signals in a vacuum environment. The combined effects of mechanical factors and current thermal effects can cause severe wear, affecting the service stability and lifespan of these components. This necessitates that the contact interfaces of such components not only possess excellent lubricity and wear resistance but also good electrical properties.

[0003] Currently, silver-based and copper-based alloys are the main lubricating materials for electrical contact components. While these alloys ensure stable operation under vacuum current-carrying conditions, they suffer from high friction coefficients and wear rates during service. This not only leads to increased wear and energy loss, reducing stability during service, but also shortens service life. Molybdenum disulfide (MoS2), as a member of the transition metal chalcogenides, possesses excellent lubrication properties due to its unique layered structure and weak interlayer van der Waals forces. Copper (Cu) has long been used as a primary conductive material due to its excellent electrical conductivity, relatively low cost, and good chemical stability. CN202210197272.X discloses a molybdenum disulfide / copper composite thin film, its preparation method, and its applications. The dry friction coefficient at room temperature is approximately 0.09~0.13, providing significant lubrication and protection. However, it suffers from drawbacks such as a cumbersome preparation process, long film deposition time, and the need for additional heating during the sulfidation process. Furthermore, its performance under vacuum and current load conditions has not been investigated. Existing molybdenum disulfide / copper composite films exhibit good tribological properties in normal working environments, but their application in harsh aerospace environments is limited, failing to meet the wear resistance requirements of components. Summary of the Invention

[0004] The purpose of this invention is to provide a molybdenum disulfide / copper composite lubricating film and its preparation method, which solves the problem that existing molybdenum disulfide / copper composite films cannot meet the wear resistance requirements of aerospace moving parts.

[0005] To address the aforementioned problems, this invention is implemented as follows: The composite lubricating film comprises a titanium transition layer and a molybdenum disulfide / copper layer, and is prepared using magnetron sputtering technology. The titanium transition layer is deposited by sputtering a titanium target with a DC power supply, and the molybdenum disulfide / copper layer is deposited by sputtering a copper target with a DC power supply and a molybdenum disulfide target with an RF power supply. The composite film prepared by this method has a uniform and dense structure, exhibits a clear preferred orientation, and possesses both excellent electrical and tribological properties.

[0006] As a further preferred embodiment, the Cu content in the molybdenum disulfide / copper layer is 7% to 22%.

[0007] As a further preferred embodiment, the composite lubricating film has a thickness of 1~1.5 µm and a static resistivity of 15~65 mΩ·cm.

[0008] As another aspect of the technical solution of the present invention, a method for preparing a molybdenum disulfide / copper composite lubricating film for use in vacuum current-carrying conditions is also provided, comprising the following steps: (1) The substrate was ultrasonically cleaned for 15 min, dried, and then placed in the deposition chamber; (2) The chamber vacuum level is set to 1×10 -3 After the pressure drops below Pa, an inert gas is introduced, and the substrate is cleaned by inert gas plasma sputtering for 5-15 minutes. (3) The inert gas is used as the sputtering gas, titanium is used as the sputtering target, and DC power supply is used as the sputtering source. A titanium transition layer is deposited on the substrate surface for 10~20 min. (4) The inert gas is used as the sputtering gas. The molybdenum disulfide target is sputtered with an RF power supply and the copper target is sputtered with a DC power supply. The copper content of the film is controlled by the opening of the baffle on the copper target. The sputtering time is 40~50 min.

[0009] As a further preferred option, the inert gas is argon.

[0010] As a further preferred option, in step (2), the argon gas has a purity of 99.99%, a base negative bias of -500 ~ -700V, and a pressure of 1 ~ 2 Pa.

[0011] As a further preferred embodiment, in step (3), the sputtering current of the titanium target is 0.2~0.4 A, the substrate negative bias voltage is -20~-50 V, and the gas pressure is 0.5~1.5 Pa.

[0012] As a further preferred embodiment, in step (4), the sputtering power of the molybdenum disulfide target is in the range of 160~200 W, the sputtering current of the copper target is 0.1 A, the substrate negative bias voltage is -20~-50 V, and the gas pressure is 0.5~1.5 Pa.

[0013] The beneficial effects of this invention are: (1) The deposition process is carried out at room temperature, without the need for additional heating and exhaust gas treatment, which is environmentally friendly; (2) Using DC power supply to sputter titanium and copper results in fast deposition rate and simple and controllable process; (3) Use radio frequency power supply to sputter molybdenum disulfide to eliminate charge accumulation on the target surface, prevent "target poisoning" and improve the deposition rate; (4) The thin film preparation method of the present invention is time-saving, with a total deposition time of less than 1 h; (5) The film of the present invention has high quality, and the film thickness is less than 1.5 µm while meeting the performance requirements; (6) The thin film structure of the present invention is uniform and dense, and has a significant (002) preferred orientation; (7) The thin film of the present invention has good electrical properties, with a static resistivity of about 15 mΩ·cm, and has both lubricity and conductivity under dynamic conditions; (8) The thin film of the present invention has excellent tribological properties under vacuum current-carrying conditions, and in a vacuum environment (<10 -3 With a load of 0.3 A current and 3 N, and reciprocating at a frequency of 3 Hz, the average coefficient of friction is approximately 0.039 (steady-state stage), and the wear rate is approximately 1.31 × 10⁻⁶. -6 mm 3 / Nm; (9) The thin film of the present invention can be used for surface friction reduction and wear resistance treatment of electrical contact sliding parts such as plug-in interfaces and conductive slip rings in the fields of aerospace and semiconductor manufacturing.

[0014] This invention utilizes MoS2 as the lubricating phase and Cu as the conductive phase, employing magnetron sputtering technology, which offers high deposition rates, high film quality, and excellent controllability, to prepare MoS2 / Cu composite lubricating materials. This composite material achieves a balance between tribological and electrical properties, providing a solution to the lubrication problems of electrically contact components in vacuum environments. Attached Figure Description

[0015] 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.

[0016] Figure 1 The surface of the MoS2 / Cu composite lubricating film prepared in Example 1 ( Figure 1 a) and cross-section ( Figure 1 b) Field emission scanning electron microscope image.

[0017] Figure 2 The image shows the X-ray diffraction pattern of the MoS2 / Cu composite lubricating film prepared in Example 1.

[0018] Figure 3 Mo 3d (MoS2 / Cu composite lubricating film prepared in Example 1) Figure 3 a) S 2p ( Figure 3 b) and Cu2p ( Figure 3 c) X-ray photoelectron spectroscopy analysis spectrum.

[0019] Figure 4 The friction coefficient curve of the MoS2 / Cu composite lubricating film prepared in Example 1 under vacuum current carrying conditions.

[0020] Figure 5 The surface of the MoS2 / Cu composite lubricating film prepared in Example 2 ( Figure 5 a) and cross-section ( Figure 5 b) Field emission scanning electron microscope image.

[0021] Figure 6 The image shows the X-ray diffraction pattern of the MoS2 / Cu composite lubricating film prepared in Example 2.

[0022] Figure 7 The friction coefficient curve of the MoS2 / Cu composite lubricating film prepared in Example 2 under vacuum current carrying conditions.

[0023] Figure 8 The surface of the MoS2 / Cu composite lubricating film prepared in Example 3 ( Figure 5 a) and cross-section ( Figure 5 b) Field emission scanning electron microscope image.

[0024] Figure 9 The image shows the X-ray diffraction pattern of the MoS2 / Cu composite lubricating film prepared in Example 3.

[0025] Figure 10 The friction coefficient curve of the MoS2 / Cu composite lubricating film prepared in Example 3 under vacuum current carrying conditions. Detailed Implementation

[0026] 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.

[0027] In this embodiment, monocrystalline silicon (100), steel (9Cr18), and soda-lime glass were selected as sputtering substrates. The choice of monocrystalline silicon (100) as the substrate was for characterization testing, while steel (9Cr18) was chosen for friction testing. This substrate material is the same as that used in the actual application of the composite lubricating film. Soda-lime glass was chosen for resistivity testing. Different substrate materials were used for different tests in this embodiment. Those skilled in the art can choose other types of substrates as needed. The composite lubricating film substrates provided by this invention are not limited to monocrystalline silicon (100), steel (9Cr18), and soda-lime glass. In all embodiments, the substrate was placed on the rotating sample stage of the deposition chamber. During plasma cleaning and film deposition, the rotating sample stage was maintained at 5 r / min until the sample was removed. Example

[0028] 1) Substrate pretreatment: Single crystal silicon (100), steel (9Cr18) and soda-lime glass were ultrasonically cleaned in petroleum ether and anhydrous ethanol for 15 min respectively, dried and placed on the rotating sample stage in the deposition chamber.

[0029] 2) Plasma cleaning: Turn on the vacuum system and pump the air pressure in the vacuum chamber to 5×10⁻⁶. -4 At 70 sccm, argon gas was introduced to maintain a stable pressure of 2 Pa. The negative bias was adjusted to -600 V, and argon plasma bombardment was performed to remove impurities and contaminants from the substrate surface. During the cleaning process, the sample stage was rotated at 5 r / min for 10 min.

[0030] 3) Deposition of Ti transition layer: Adjust the chamber pressure to 1 Pa and the substrate negative bias voltage to -30 V; turn on the DC power supply of Ti target, adjust the current to 0.3 A, and deposit for 15 min.

[0031] 4) Deposition of Cu-doped MoS2 layer: Maintain chamber pressure at 1 Pa and substrate negative bias at -30 V; turn on the RF power supply of MoS2 target and adjust the power to 180 W; adjust the opening of the baffle on Cu target to 45%; turn on the DC power supply of Cu target and adjust the current to 0.1 A; after deposition for 40 min, turn off the power supply and substrate negative bias, and allow it to cool naturally in argon atmosphere for 1 h, then release the vacuum and take out the sample.

[0032] See Figure 1 The surface of Example 1 was examined using a field emission scanning electron microscope at magnifications of 2.5W and 1.5W. Figure 1 a) and cross-section ( Figure 1 b) Morphological analysis revealed a dense structure with copper uniformly distributed within molybdenum disulfide. The Ti transition layer thickness was 80 nm, and the total thickness of the composite film was approximately 1.06 µm. (See reference...) Figure 2 Grazing incidence X-ray diffraction analysis was performed on Example 1. X-ray irradiation of the sample surface revealed that the incident angle corresponding to the diffraction peaks was approximately 13°~15°, indicating that the film exhibited a significant (002) preferred orientation. This structure is more conducive to interlayer slip during friction, demonstrating good lubricity. Mo3d ( Figure 3 a) S 2p ( Figure 3 b) and Cu 2p ( Figure 3 c) X-ray photoelectron spectroscopy analysis, results are available in the [reference needed] section. Figure 3 Due to residual oxygen in the vacuum chamber and unavoidable oxidation during film transfer, two substances, MoO3 and CuSO3, appeared in the film; however, its basic composition remained MoS2 and Cu. Energy dispersive spectroscopy (EDS) analysis was performed on Example 1. Electron beam bombardment of the sample surface excited characteristic X-rays of copper in the sample. By detecting the energy and intensity of these X-rays, the Cu content of the monolayer MoS2 / Cu film was determined to be approximately 15%. The static resistivity of the film in Example 1 was measured to be 17 mΩ·cm using an RTS-9 dual-electrode four-probe tester. (See reference...) Figure 4 Anton Paar's TRB3 friction tester was used, with 9Cr18 steel balls of 6 mm diameter as the grinding balls. Example 1 was conducted in a vacuum environment (<10). -3 With a load of 0.3 A current and 3 N, and reciprocating at a frequency of 3 Hz, the average coefficient of friction is approximately 0.039 (steady-state stage), and the wear rate is approximately 1.31 × 10⁻⁶. -6 mm 3 / Nm. Example

[0033] 1) Substrate pretreatment: Single crystal silicon (100), steel (9Cr18) and soda-lime glass were ultrasonically cleaned in petroleum ether and anhydrous ethanol for 15 min respectively. After drying, they were placed on the sample selection stage in the deposition chamber and the sample stage speed was maintained at 5 r / min until the coating was completed.

[0034] 2) Plasma cleaning: Turn on the vacuum system and pump the air pressure in the vacuum chamber to 5×10⁻⁶. -4 At 70 sccm, argon gas is introduced to maintain a stable pressure of 2 Pa; the negative bias is adjusted to -600 V, and argon plasma bombardment is performed to remove impurities and contaminants from the substrate surface. The cleaning process lasts for 10 minutes.

[0035] 3) Deposition of Ti transition layer: Adjust the chamber pressure to 1 Pa and the substrate negative bias voltage to -30 V; turn on the DC power supply of Ti target, adjust the current to 0.3 A, and deposit for 15 min.

[0036] 4) Deposition of Cu-doped MoS2 layer: Maintain chamber pressure at 1 Pa and substrate negative bias at -30 V; turn on the RF power supply of MoS2 target and adjust the power to 180 W; adjust the opening of the baffle on Cu target to 25%; turn on the DC power supply of Cu target and adjust the current to 0.1 A; after deposition for 40 min, turn off the power supply and substrate negative bias, and allow it to cool naturally in argon atmosphere for 1 h, then release the vacuum and remove the sample.

[0037] See Figure 5 For the surface of Example 2 ( Figure 5 a) and cross-section ( Figure 5 b) Morphological analysis revealed that the film has a dense structure, with a total composite film thickness of approximately 1.30 µm. (See also...) Figure 6 Grazing-incidence X-ray diffraction analysis of Example 2 revealed a significant (002) preferred orientation in the thin film. Energy dispersive spectroscopy (EDS) analysis of Example 2 showed a Cu content of approximately 7%. Four-probe analysis of Example 2 revealed a static resistivity of 60 mΩ·cm. See also... Figure 7 Anton Paar's TRB3 friction tester was used, with 9Cr18 steel balls of 6 mm diameter as the grinding balls. Example 2 was conducted in a vacuum environment (<10). -3 With a load of 0.3 A current and 3 N, and reciprocating at a frequency of 3 Hz, the average coefficient of friction is approximately 0.044 (steady-state stage), and the wear rate is approximately 1.53 × 10⁻⁶. -6 mm 3 / Nm. Example

[0038] 1) Substrate pretreatment: Single crystal silicon (100), steel (9Cr18) and soda-lime glass were ultrasonically cleaned in petroleum ether and anhydrous ethanol for 15 min respectively. After drying, they were placed on the sample selection stage in the deposition chamber and the sample stage speed was maintained at 5 r / min until the coating was completed.

[0039] 2) Plasma cleaning: Turn on the vacuum system and pump the air pressure in the vacuum chamber to 5×10⁻⁶. -4 At 70 sccm, argon gas is introduced to maintain a stable pressure of 2 Pa; the negative bias is adjusted to -600 V, and argon plasma bombardment is performed to remove impurities and contaminants from the substrate surface. The cleaning process lasts for 10 minutes.

[0040] 3) Deposition of Ti transition layer: Adjust the chamber pressure to 1 Pa and the substrate negative bias voltage to -30 V; turn on the DC power supply of Ti target, adjust the current to 0.3 A, and deposit for 15 min.

[0041] 4) Deposition of Cu-doped MoS2 layer: Maintain chamber pressure at 1 Pa and substrate negative bias at -30 V; turn on the RF power supply of MoS2 target and adjust the power to 180 W; adjust the opening of the baffle on Cu target to 75%; turn on the DC power supply of Cu target and adjust the current to 0.1 A; after deposition for 40 min, turn off the power supply and substrate negative bias, allow to cool naturally in argon atmosphere for 1 h, and then release the vacuum to remove the sample.

[0042] See Figure 8 For the surface of Example 3 ( Figure 8 a) and cross-section ( Figure 8 b) Morphological analysis revealed that the film has a dense structure, with a total composite film thickness of approximately 1.15 µm. (See also...) Figure 9 Grazing-incidence X-ray diffraction analysis of Example 3 showed that the film exhibited a significant (002) preferred orientation. Energy dispersive spectroscopy (EDS) analysis of Example 3 revealed that the Cu content of the film was approximately 22%. Four-probe analysis of Example 3 showed that the static resistivity of the film was 19 mΩ·cm. See also... Figure 10 Anton Paar's TRB3 friction tester was used, with 9Cr18 steel balls of 6 mm diameter as grinding balls. Example 3 was conducted in a vacuum environment (<10). -3 With a load of 0.3 A current and 3 N, and reciprocating at a frequency of 3 Hz, the average coefficient of friction is approximately 0.058 (steady-state stage), and the wear rate is approximately 9.89 × 10⁻⁶. -7 mm 3 / Nm.

[0043] This invention utilizes MoS2 as the lubricating phase and Cu as the conductive phase, employing magnetron sputtering technology, which offers high deposition rates, high film quality, and excellent controllability, to prepare MoS2 / Cu composite lubricating materials. This composite material achieves a balance between tribological and electrical properties, providing a solution to the lubrication problems of electrically contact components in vacuum environments.

Claims

1. A molybdenum disulfide / copper composite lubricating film, characterized in that, The composite lubricating film comprises a titanium transition layer and a molybdenum disulfide / copper layer, and is prepared using magnetron sputtering technology. The titanium transition layer is deposited by sputtering a titanium target with a DC power supply, and the molybdenum disulfide / copper layer is deposited by sputtering a copper target with a DC power supply and a molybdenum disulfide target with an RF power supply.

2. The molybdenum disulfide / copper composite lubricating film according to claim 1, characterized in that, The Cu content in the molybdenum disulfide / copper layer is 7% to 22%.

3. The molybdenum disulfide / copper composite lubricating film according to claim 1, characterized in that, The composite lubricating film has a thickness of 1~1.5 µm and a static resistivity of 15~65 mΩ·cm.

4. The method for preparing the molybdenum disulfide / copper composite lubricating film as described in claim 1, characterized in that, Includes the following steps: (1) Clean the substrate with ultrasonic cleaner for 15 min, dry it and place it in the deposition chamber; (2) The chamber vacuum level is set to 1×10 -3 After the pressure drops below Pa, an inert gas is introduced, and the substrate is cleaned by inert gas plasma sputtering for 5-15 minutes. (3) The inert gas is used as the sputtering gas, titanium is used as the sputtering target, and DC power supply is used as the sputtering source. A titanium transition layer is deposited on the substrate surface for 10~20 min. (4) The inert gas is used as the sputtering gas. The molybdenum disulfide target is sputtered with an RF power supply and the copper target is sputtered with a DC power supply. The copper content of the film is controlled by the opening of the baffle on the copper target. The sputtering time is 40~50 min.

5. The preparation method according to claim 4, characterized in that, The inert gas is argon.

6. The preparation method according to claim 5, characterized in that, In step (2), the argon gas has a purity of 99.99%, a base negative bias of -500 ~ -700 V, and a gas pressure of 1 ~ 2 Pa.

7. The preparation method according to claim 4, characterized in that, In step (3), the sputtering current of the titanium target is 0.2~0.4 A, the negative bias voltage of the substrate is -20~-50 V, and the gas pressure is 0.5~1.5 Pa.

8. The preparation method according to claim 4, characterized in that, In step (4), the sputtering power of the molybdenum disulfide target is in the range of 160~200 W, the sputtering current of the copper target is 0.1 A, the substrate negative bias voltage is -20~-50 V, and the gas pressure is 0.5~1.5 Pa.

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