Titanium-doped molybdenum disulfide super-slippery film, and preparation method and application thereof

Abstract

The application relates to a titanium-doped molybdenum disulfide super-smooth film and a preparation method and application thereof. The titanium-doped molybdenum disulfide super-smooth film comprises a titanium transition layer, a molybdenum disulfide / titanium gradient transition layer and a molybdenum disulfide / titanium functional layer which are sequentially formed on the surface of a substrate; wherein the atomic content of titanium in the functional layer is 7at%-13at%, and the rest is molybdenum disulfide. The titanium-doped molybdenum disulfide super-smooth film is suitable for a vacuum environment and can realize a super-smooth (friction coefficient less than 0.01) effect in the vacuum environment.

Description

Technical Field

[0001] This article relates to the field of surface lubrication coating materials technology, and in particular to a titanium-doped molybdenum disulfide superlubricating coating for use in vacuum environments, its preparation method and application. Background Technology

[0002] Friction and wear are key factors leading to performance degradation and failure of mechanical systems. Studies show that in the transportation sector, approximately 30% of fuel energy consumption is spent overcoming various frictional resistances; and in mechanical failure cases, up to 80% of failure modes are directly related to friction and wear. With the development of modern equipment towards high performance, tribological problems under extreme service environments are becoming increasingly prominent. Major engineering equipment, such as space stations and nuclear power plants, often need to operate stably for extended periods under conditions of multi-physical field coupling, including vacuum, strong radiation, and alternating high and low temperatures. This poses unprecedented challenges to the comprehensive performance of lubricating materials. Superlubricity technology, as an important approach to achieving extremely low friction (friction coefficient less than 0.01), theoretically requires the simultaneous fulfillment of three basic conditions: a contaminated friction interface, complete saturation of surface defects, and interlayer slip without lattice deformation. However, in engineering practice, especially on a macroscopic scale, achieving these conditions simultaneously presents significant difficulties, becoming a major bottleneck restricting the engineering application of superlubricity technology. Therefore, it is of great strategic significance to seek breakthroughs in materials design (such as nanocomposites) and surface engineering (such as texturing) through multidisciplinary innovation, and to develop new lubricating material systems that combine high load-bearing capacity, ultra-low friction characteristics and excellent environmental adaptability.

[0003] Molybdenum disulfide (MoS2), a typical layered solid lubricant, is widely used in aerospace, nuclear power equipment, and precision machinery due to its unique crystal structure and low shear properties. However, this material exhibits significant environmental sensitivity during practical use, particularly in humid environments where it is prone to oxidation, leading to a significant decrease in frictional performance. This oxidation not only increases the coefficient of friction but also accelerates the wear process, severely impacting its service life. In spacecraft applications, MoS2 lubricating films face even more severe challenges. Moving components in spacecraft undergo various extreme environmental conditions throughout their service life, including high humidity during ground storage, vibration and shock during launch, and drastic temperature changes during orbital operation. These complex environmental factors place extremely high demands on the chemical stability and mechanical properties of MoS2 films. Furthermore, MoS2 itself has relatively low hardness, making it prone to interfacial delamination and excessive wear under high-speed operation or heavy-load conditions. To overcome these technical challenges, researchers are actively exploring the development of MoS2-based nanocomposite films. By employing material composite methods, the excellent lubrication properties of MoS2 can be maintained while its hardness and environmental stability are improved. This is of great significance for ensuring the long-term reliable operation of critical equipment such as aerospace transmission systems and nuclear reactor control mechanisms. The development of this novel composite film represents an important direction in the field of solid lubricating materials.

[0004] Elemental doping is an effective way to improve the moisture resistance and mechanical properties of MoS2 thin films. For example: Chinese Patent 1: Application No. 202411235936.2, entitled "An Adaptive Molybdenum Disulfide-Based Multilayer Composite Thin Film Resistant to Low Earth Orbit Irradiation and Its Preparation Method." This patent proposes a multilayer coating of titanium-doped molybdenum disulfide thin film, which can effectively reduce the mechanical wear of moving parts in space machinery and maintain stable tribological properties even after long-term irradiation in low Earth orbit.

[0005] Chinese Patent 2: Application No. 202311541172.5, entitled "A Wear-Resistant Molybdenum Disulfide-Based Composite Film and Its Preparation Method." This patent controls the Ti content in the functional layer MoS2-Ti, allowing Ti to exist in solid solution form. Without damaging the layered structure and lubrication properties of the MoS2 film, it significantly reduces the environmental sensitivity and friction coefficient of MoS2, thereby significantly improving the wear resistance life of the MoS2 composite film.

[0006] As discussed above, elemental doping of molybdenum disulfide coatings can effectively improve their environmental sensitivity and mechanical properties. However, current structural designs for molybdenum disulfide coatings still have shortcomings, resulting in a relatively high coefficient of friction and preventing the achievement of super-lubricity. Summary of the Invention

[0007] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of protection of this application.

[0008] The purpose of this application is to provide a titanium-doped molybdenum disulfide superlubricated thin film suitable for vacuum environments, its preparation method, and its application.

[0009] This application provides a titanium-doped molybdenum disulfide superlubricated thin film suitable for vacuum environments. The titanium-doped molybdenum disulfide superlubricated thin film includes a titanium transition layer, a gradient transition layer, and a functional layer sequentially formed on the surface of a substrate. The titanium-doped molybdenum disulfide superlubricated thin film is prepared by first turning on a DC magnetron sputtering power supply and opening the titanium target baffle while closing other target baffles to deposit a titanium transition layer on the substrate. Then, all target baffles are turned on simultaneously, and the target current is controlled to gradually increase to deposit the gradient transition layer. Finally, the target current is kept stable to prepare the functional layer.

[0010] The first aspect of this application provides a titanium-doped molybdenum disulfide superlubricating thin film, the superlubricating thin film comprising a titanium transition layer, a molybdenum disulfide / titanium gradient transition layer and a molybdenum disulfide / titanium functional layer sequentially formed on the surface of a substrate.

[0011] In one exemplary embodiment, in the molybdenum disulfide / titanium functional layer, the metallic titanium is uniformly distributed between molybdenum disulfide molecules.

[0012] In one exemplary embodiment, the molybdenum disulfide / titanium functional layer contains 7 at% to 13 at% titanium atoms, with the remainder being molybdenum disulfide.

[0013] In one exemplary embodiment, the molybdenum disulfide / titanium functional layer contains 7 at% or 13 at% titanium atoms, with the remainder being molybdenum disulfide.

[0014] In one exemplary embodiment, in the molybdenum disulfide / titanium gradient transition layer, along the direction from the titanium transition layer to the molybdenum disulfide / titanium functional layer, the titanium content gradually decreases to the same level as the titanium content in the molybdenum disulfide / titanium functional layer, and the molybdenum disulfide content gradually increases to the same level as the molybdenum disulfide content in the molybdenum disulfide / titanium functional layer.

[0015] In one exemplary embodiment, the total thickness of the titanium-doped molybdenum disulfide superlubricating film is 3-6 μm.

[0016] In one exemplary embodiment, the thickness of the titanium transition layer is 50-500 nm.

[0017] In one exemplary embodiment, the thickness of the molybdenum disulfide / titanium gradient transition layer is 50-500 nm.

[0018] In one exemplary embodiment, the thickness of the molybdenum disulfide / titanium functional layer is 2-5 μm.

[0019] In one exemplary embodiment, the total thickness of the titanium-doped molybdenum disulfide superlubricated film is 3.78 μm, the thickness of the titanium transition layer is 0.2 nm, the thickness of the molybdenum disulfide / titanium gradient transition layer is 0.2 nm, and the thickness of the molybdenum disulfide / titanium functional layer is 3.38 μm; or The total thickness of the titanium-doped molybdenum disulfide superlubricated film is 3.85 μm, the thickness of the titanium transition layer is 0.2 nm, the thickness of the molybdenum disulfide / titanium gradient transition layer is 0.2 nm, and the thickness of the molybdenum disulfide / titanium functional layer is 3.45 μm.

[0020] In one exemplary embodiment, the substrate is made of any one or more combinations of GCr15 steel, TC4 alloy, 4169 high-temperature alloy, and silicon wafer.

[0021] In one exemplary embodiment, the titanium-doped molybdenum disulfide superlubricated thin film is produced under a vacuum of 5 × 10⁻⁶. -3 The coefficient of friction at Pa is less than 0.01.

[0022] The second aspect of this application provides a method for preparing the above-mentioned titanium-doped molybdenum disulfide superlubricated thin film. The target material used in the method includes two molybdenum disulfide targets and two titanium targets. During the preparation process, different structures are deposited by controlling the opening and closing of the baffle in front of the target material.

[0023] In one exemplary embodiment, the method includes the following steps: Step 1, substrate surface treatment: ultrasonic cleaning is performed on the substrate that has been ground and polished. The cleaned substrate is then placed in the vacuum chamber of a multi-target magnetron sputtering equipment, and inert gas is introduced for glow discharge cleaning. Step 2: Titanium transition layer deposition. After glow discharge cleaning, adjust the flow rate of the inert gas, open the baffle in front of the titanium target, close the baffle in front of the molybdenum disulfide target, adjust the DC bias, pulse bias and duty cycle parameters, set the current value of the titanium target, and deposit the titanium transition layer using DC magnetron sputtering. Step 3: Deposition of molybdenum disulfide / titanium gradient transition layer. Open the baffle in front of the titanium target and the molybdenum disulfide target, gradually decrease the current of the titanium target, and gradually increase the current of the molybdenum disulfide target. The current changes with the time gradient to the required value to complete the deposition. Step 4: Deposition of molybdenum disulfide / titanium functional layer. DC magnetron sputtering is initiated on the surface of the molybdenum disulfide / titanium gradient transition layer. The currents of the titanium target and the molybdenum disulfide target are fixed for deposition. After completion, the titanium-doped molybdenum disulfide superlubricated thin film is obtained.

[0024] In one exemplary embodiment, step one, the ultrasonic cleaning includes: immersing the substrate that has been ground and polished in an ethanol solution and cleaning it with an ultrasonic cleaning device for 10-15 minutes (e.g., 10 minutes), and then placing the substrate in an acetone solution and cleaning it with an ultrasonic cleaning device for 10-15 minutes (e.g., 10 minutes).

[0025] In one exemplary embodiment, step one, the glow discharge cleaning includes: clamping the ultrasonically cleaned substrate in a coating chamber and evacuating it to a vacuum level below 5 × 10⁻⁶. -3 After Pa, an inert gas is introduced at a flow rate of 30-80 sccm (e.g., 30 sccm). The substrate bias voltage is adjusted to 120-150V (e.g., 120V). The Hall ion source is turned on, and the substrate is subjected to argon ion glow discharge cleaning for 30-60 minutes (e.g., 30 minutes).

[0026] In one exemplary embodiment, step two, the deposition of the titanium transition layer includes: after completing glow discharge cleaning, disabling the Hall ion source, adjusting the inert gas flow rate, opening the front baffle of the titanium target, closing the front baffle of the molybdenum disulfide target, setting the titanium target current to 4-6A (e.g., 5A), and the deposition time to 1000-1500s (e.g., 1000s), and depositing the titanium transition layer using a DC magnetron sputtering process.

[0027] In one exemplary embodiment, in step three, the titanium target current is reduced from 4-6A to 0.6-3A, the molybdenum disulfide target current is increased from 0A to 4-6A, and the deposition time is 400-800s.

[0028] In one exemplary embodiment, in step three, the titanium target current is reduced from 5A to 0.6A, the molybdenum disulfide target current is increased from 0A to 5A, and the deposition time is 600s; or In step three, the titanium target current is reduced from 5A to 1.2A, the molybdenum disulfide target current is increased from 0A to 5A, and the deposition time is 600s.

[0029] In one exemplary embodiment, in step four, the titanium target current is 0.6-3A, the molybdenum disulfide target current is 4-6A, and the deposition time is 4-8h.

[0030] In one exemplary embodiment, in step four, the titanium target current is 0.6A, the molybdenum disulfide target current is 5A, and the deposition time is 6 hours; or In step four, the titanium target current is 1.2A, the molybdenum disulfide target current is 5A, and the deposition time is 6 hours.

[0031] In one exemplary embodiment, in steps two, three, and four, the DC bias voltage of the substrate is -50 to -60V (e.g., -50V), the inert gas flow rate is 18-20 sccm (e.g., 18 sccm), the chamber pressure is 0.5-0.8 Pa (e.g., 0.5 Pa), and the substrate temperature is 150-200°C (e.g., 150°C).

[0032] In one exemplary embodiment, in steps two, three and four, the rotation speed of the deposition workpiece holder is 1-3 rpm (e.g., 2 rpm).

[0033] In one exemplary embodiment, the inert gas is argon.

[0034] The third aspect of this application provides a titanium-doped molybdenum disulfide superlubricating thin film prepared by the above method.

[0035] The fourth aspect of this application provides the use of the above-mentioned molybdenum disulfide composite film as a solid lubricant in aerospace, nuclear energy equipment or precision machinery in a vacuum.

[0036] In one exemplary embodiment, the vacuum level is 5 × 10⁻⁶. -3 Pa.

[0037] Compared with existing related technologies, this application uses DC magnetron sputtering technology to control the magnitude of the target current to regulate the ratio of molybdenum disulfide and titanium in the thin film, and adds titanium doping to the interlayer of molybdenum disulfide molecules to prepare a titanium-doped molybdenum disulfide thin film that can achieve a super-lubricating effect in a vacuum environment, and the film-substrate adhesion of the film meets the requirements.

[0038] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the embodiments described in the description and the accompanying drawings. Attached Figure Description

[0039] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0040] Figure 1 The titanium-doped molybdenum disulfide superlubricated films prepared in the examples and comparative examples were subjected to a temperature of 5 × 10⁻⁶. -3 Friction coefficient curve under vacuum environment (Pa); Figure 2 XRD images of titanium-doped molybdenum disulfide superlubricated films with titanium contents of 7%, 13%, 16%, 18%, and 22%; Figure 3EDS images of titanium elements in titanium-doped molybdenum disulfide superlubricated films with titanium contents of 7%, 13%, 16%, 18%, and 22%. Figure 4 Cross-sectional SEM images of titanium-doped molybdenum disulfide superlubricated films with titanium contents of 7%, 13%, 16%, 18%, and 22%; Figure 5 The results are obtained from the high-load scratch test of titanium-doped molybdenum disulfide superlubricated thin films with titanium contents of 7%, 13%, 16%, 18%, and 22%. Detailed Implementation

[0041] 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be arbitrarily combined with each other.

[0042] The present application will be further described in detail below with reference to specific embodiments, but these embodiments should not be construed as limiting the present application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this invention.

[0043] The raw materials used in this application are all conventional products on the market.

[0044] Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0045] Experimental methods not specified in the examples are generally performed under standard conditions or as recommended by the manufacturer.

[0046] Example 1 The preparation method of the titanium-doped molybdenum disulfide superlubricated thin film in this embodiment is as follows: Step 1: Substrate surface treatment. The substrate material is selected as 4169 high-temperature alloy. After grinding and polishing, the substrate is immersed in an ethanol solution and ultrasonically cleaned for 10 minutes. Then, the substrate is immersed in an acetone solution and ultrasonically cleaned for another 10 minutes. The ultrasonically cleaned substrate is then clamped in the coating chamber, which is evacuated to a vacuum level below 5 × 10⁻⁶. -3 After Pa, argon gas is introduced at a flow rate of 30 sccm. The substrate bias voltage is adjusted to 120V, the Hall ion source is turned on, and the substrate is subjected to argon ion glow discharge cleaning for 30 minutes. Step 2: Titanium transition layer deposition. After argon ion glow discharge cleaning, the Hall ion source is turned off, and argon gas is introduced into the vacuum chamber at a rate of 18 sccm. The front baffle of the titanium target is opened, and the front baffle of the molybdenum disulfide target is closed. The titanium target current is set to 5A, the substrate bias voltage is -50V, the chamber pressure is 0.5 Pa, and the substrate temperature is 150℃. The titanium transition layer is deposited using DC magnetron sputtering technology, and the titanium transition layer is generated after a deposition time of 1000s. Step 3: Deposition of the molybdenum disulfide / titanium gradient transition layer. Open the front baffles of the titanium target and the molybdenum disulfide target. Within 600s, reduce the titanium target current from 5A to 0.6A and increase the molybdenum disulfide target current from 0A to 5A to complete the deposition of the gradient transition layer. During this process, the substrate bias voltage is -50V, the inert gas flow rate is 18sccm, the substrate temperature is 150℃, and the chamber pressure is 0.5Pa. Step 4: Deposition of the molybdenum disulfide / titanium functional layer. DC magnetron sputtering is initiated on the surface of the molybdenum disulfide / titanium gradient transition layer. The titanium target current is fixed at 0.6 A, the molybdenum disulfide target current is fixed at 5 A, the substrate bias voltage is -50 V, the inert gas flow rate is 18 sccm, the substrate temperature is 150 °C, and the chamber pressure is 0.5 Pa. After 6 hours of deposition, the titanium-doped molybdenum disulfide superlubricating film suitable for vacuum conditions is obtained.

[0047] In steps two, three, and four, the rotation speed of the deposition workpiece holder is 2 rpm.

[0048] In Example 1, the titanium-doped molybdenum disulfide superlubricating film was tested and found to have a titanium atomic content of 7 at%. (See also...) Figure 4 The total thickness of the titanium-doped molybdenum disulfide superlubricated film with a titanium content of 7 at% is 3.78 μm, the titanium transition layer thickness is 0.20 μm, the molybdenum disulfide / titanium gradient transition layer thickness is 0.2 μm, and the functional layer thickness is 3.38 μm.

[0049] Example 2 The preparation method of the titanium-doped molybdenum disulfide superlubricated thin film in this embodiment is as follows: Step 1: Substrate surface treatment. The substrate material is selected as 4169 high-temperature alloy. After grinding and polishing, the substrate is immersed in an ethanol solution and ultrasonically cleaned for 10 minutes. Then, the substrate is immersed in an acetone solution and ultrasonically cleaned for another 10 minutes. The ultrasonically cleaned substrate is then clamped in the coating chamber, which is evacuated to a vacuum level below 5 × 10⁻⁶. -3 After Pa, argon gas is introduced at a flow rate of 30 sccm. The substrate bias voltage is adjusted to 120V, the Hall ion source is turned on, and the substrate is subjected to argon ion glow discharge cleaning for 30 minutes. Step 2: Titanium transition layer deposition. After argon ion glow discharge cleaning, the Hall ion source is turned off, and argon gas is introduced into the vacuum chamber at a rate of 18 sccm. The front baffle of the titanium target is opened, and the front baffle of the molybdenum disulfide target is closed. The titanium target current is set to 5A, the substrate bias voltage is -50V, the chamber pressure is 0.5 Pa, and the substrate temperature is 150℃. The titanium transition layer is deposited using DC magnetron sputtering technology, and the titanium transition layer is generated after a deposition time of 1000s. Step 3: Deposition of the molybdenum disulfide / titanium gradient transition layer. Open the front baffles of the titanium target and the molybdenum disulfide target. Within 600s, reduce the titanium target current from 5A to 1.2A and increase the molybdenum disulfide target current from 0A to 5A to complete the deposition of the gradient transition layer. During this process, the substrate bias voltage is -50V, the inert gas flow rate is 18sccm, the substrate temperature is 150℃, and the chamber pressure is 0.5Pa. Step 4: Deposition of the molybdenum disulfide / titanium functional layer. DC magnetron sputtering is initiated on the surface of the molybdenum disulfide / titanium gradient transition layer. The titanium target current is fixed at 1.2 A, the molybdenum disulfide target current is fixed at 5 A, the substrate bias voltage is -50 V, the inert gas flow rate is 18 sccm, the substrate temperature is 150 °C, and the chamber pressure is 0.5 Pa. After 6 hours of deposition, the titanium-doped molybdenum disulfide superlubricated thin film suitable for vacuum conditions is obtained.

[0050] In steps two, three, and four, the rotation speed of the deposition workpiece holder is 2 rpm.

[0051] In Example 2, the titanium-doped molybdenum disulfide superlubricating film was tested and found to have an atomic content of 13 at%. (See also...) Figure 4 The total thickness of the titanium-doped molybdenum disulfide superlubricated film with a titanium content of 13 at% is 3.85 μm, the titanium transition layer thickness is 0.20 μm, the gradient transition layer thickness is 0.2 μm, and the functional layer thickness is 3.45 μm.

[0052] Comparative Example 1 The preparation method of the titanium-doped molybdenum disulfide superlubricated thin film in this comparative example is as follows: Step 1: Substrate surface treatment. The substrate material is selected as 4169 high-temperature alloy. After grinding and polishing, the substrate is immersed in an ethanol solution and ultrasonically cleaned for 10 minutes. Then, the substrate is immersed in an acetone solution and ultrasonically cleaned for another 10 minutes. The ultrasonically cleaned substrate is then clamped in the coating chamber, which is evacuated to a vacuum level below 5 × 10⁻⁶. -3 After Pa, argon gas is introduced at a flow rate of 30 sccm. The substrate bias voltage is adjusted to 120V, the Hall ion source is turned on, and the substrate is subjected to argon ion glow discharge cleaning for 30 minutes. Step 2: Titanium transition layer deposition. After argon ion glow discharge cleaning, the Hall ion source is turned off, and argon gas is introduced into the vacuum chamber at a rate of 18 sccm. The front baffle of the titanium target is opened, and the front baffle of the molybdenum disulfide target is closed. The titanium target current is set to 5A, the substrate bias voltage is -50V, the chamber pressure is 0.5 Pa, and the substrate temperature is 150℃. The titanium transition layer is deposited using DC magnetron sputtering technology, and the titanium transition layer is generated after a deposition time of 1000s. Step 3: Deposition of molybdenum disulfide / titanium gradient transition layer. Open the front baffles of the titanium target and the molybdenum disulfide target. Within 600s, reduce the titanium target current from 5A to 1.8A and increase the molybdenum disulfide target current from 0A to 5A. The current changes with the time gradient within 600s to the value required for the functional layer, thus completing the deposition of the gradient transition layer. The substrate bias voltage is -50V, the inert gas flow rate is 18sccm, the substrate temperature is 150℃, and the chamber pressure is 0.5Pa. Step 4: Deposition of the molybdenum disulfide / titanium functional layer. DC magnetron sputtering is initiated on the surface of the molybdenum disulfide / titanium gradient transition layer. The titanium target current is fixed at 1.8 A, the molybdenum disulfide target current is fixed at 5 A, the substrate bias voltage is -50 V, the inert gas flow rate is 18 sccm, the substrate temperature is 150 °C, and the chamber pressure is 0.5 Pa. After 6 hours of deposition, the titanium-doped molybdenum disulfide superlubricated thin film suitable for vacuum conditions is obtained.

[0053] In steps two, three, and four, the rotation speed of the deposition workpiece holder is 2 rpm.

[0054] In Comparative Example 1, the titanium-doped molybdenum disulfide superlubricating film was tested and found to have an atomic content of 16 at%. (See also...) Figure 4 The total thickness of the titanium-doped molybdenum disulfide superlubricated film with a titanium content of 16 at% is 4.09 μm, the titanium transition layer thickness is 0.20 μm, the gradient transition layer thickness is 0.20 μm, and the functional layer thickness is 3.69 μm.

[0055] Comparative Example 2 The difference from Example 1 is that in step four, the current of the titanium target is fixed at 2.4A.

[0056] In this comparative example, the titanium-doped molybdenum disulfide superlubricating film was tested and found to have a titanium atomic content of 18 at%. (See also...) Figure 4 The total thickness of the titanium-doped molybdenum disulfide superlubricated film with 18 at% titanium content is 4.56 μm, the titanium transition layer thickness is 0.20 μm, the gradient transition layer thickness is 0.20 μm, and the functional layer thickness is 4.16 μm.

[0057] Comparative Example 3 The difference from Example 1 is that in step four, the current of the titanium target is fixed at 3A.

[0058] In Comparative Example 3, the titanium-doped molybdenum disulfide superlubricating film was tested and found to have an atomic content of 22 at%. (See also...) Figure 1 The total thickness of the titanium-doped molybdenum disulfide superlubricated film with a titanium content of 22 at% is 5.56 μm, the titanium transition layer thickness is 0.20 μm, the gradient transition layer thickness is 0.20 μm, and the functional layer thickness is 5.46 μm.

[0059] Friction test: A reciprocating ball-disc friction and wear testing machine was used, at a speed of 5×10. -3 Under a vacuum environment, the grinding balls coated with the thin films of the examples and comparative examples were Φ6mm GCr15 steel balls, with a load of 5N, a sliding stroke of 4mm, a frequency of 4Hz, and a sampling frequency of 120Hz. The friction coefficient versus time curves were obtained, and the results are shown in [Figure showing results]. Figure 1 .

[0060] according to Figure 5 It can be seen that the titanium-doped molybdenum disulfide superlubricated thin films described in Examples 1 and 2, under a vacuum degree of 5 × 10⁻⁶, achieve the desired effect. -3 Under Pa conditions, the coefficient of friction is less than 0.01, achieving a superlubricated state. However, the comparative examples do not achieve superlubricity. Therefore, superlubricity can only be achieved when the atomic content of titanium is less than 13 at%.

[0061] Membrane-substrate bonding strength test: The film-substrate adhesion was tested on the films in the examples and comparative examples, and the effect of different titanium contents on the film-substrate adhesion was statistically analyzed. The results are shown in [Figure Number]. Figure 5 .

[0062] See ​ The results of the membrane substrate high load scratch test show that the membrane substrate bonding force gradually increases when the atomic content of titanium is less than 13 at%, and decreases when it is greater than 13 at%.

[0063] In summary, this application employs DC magnetron sputtering technology to control the magnitude of the target current to regulate the ratio of molybdenum disulfide and titanium in the thin film, adding titanium doping to the interlayer of molybdenum disulfide molecules, thus preparing a titanium-doped molybdenum disulfide thin film that achieves a super-lubricating effect under vacuum, and the film-substrate adhesion of the film meets the requirements.

[0064] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A titanium-doped molybdenum disulfide superlubricated thin film, comprising a titanium transition layer, a molybdenum disulfide / titanium gradient transition layer and a molybdenum disulfide / titanium functional layer sequentially formed on the surface of a substrate, wherein the molybdenum disulfide / titanium functional layer has an atomic content of titanium of 7 at%-13 at%, and the remainder is molybdenum disulfide.

2. The titanium-doped molybdenum disulfide superlubricated thin film according to claim 1, wherein, The total thickness of the titanium-doped molybdenum disulfide superlubricated film is 3-6 μm; and / or The thickness of the titanium transition layer is 50-500 nm; and / or The thickness of the molybdenum disulfide / titanium gradient transition layer is 50-500 nm; and / or The thickness of the molybdenum disulfide / titanium functional layer is 2-5 μm.

3. The titanium-doped molybdenum disulfide superlubricated thin film according to claim 1 or 2, wherein, The substrate material includes any one or more combinations of GCr15 steel, TC4 alloy, 4169 high-temperature alloy, and silicon wafers.

4. The titanium-doped molybdenum disulfide superlubricated thin film according to claim 1 or 2, wherein, The titanium-doped molybdenum disulfide superlubricated thin film was produced under a vacuum of 5 × 10⁻⁶. -3 The coefficient of friction at Pa is less than 0.

01.

5. A method for preparing a titanium-doped molybdenum disulfide superlubricated thin film according to any one of claims 1 to 4, wherein the target material used in the method comprises two molybdenum disulfide targets and two titanium targets; The method includes the following steps: Step 1, substrate surface treatment, including: ultrasonic cleaning of the substrate that has been ground and polished, placing the cleaned substrate into the vacuum chamber of a multi-target magnetron sputtering equipment, introducing inert gas, and performing glow discharge cleaning; Step 2, titanium transition layer deposition, includes: after completing glow discharge cleaning, adjusting the flow rate of the inert gas, opening the front baffle of the titanium target, closing the front baffle of the molybdenum disulfide target, adjusting the substrate DC bias voltage, pulse bias voltage and duty cycle parameters, setting the titanium target current value, and depositing the titanium transition layer using DC magnetron sputtering process. Step 3, deposition of molybdenum disulfide / titanium gradient transition layer, including: opening the front baffles of the titanium target and the molybdenum disulfide target, gradually decreasing the current of the titanium target, gradually increasing the current of the molybdenum disulfide target, and changing the current with time gradient to the required value to complete the deposition; Step four, molybdenum disulfide / titanium functional layer deposition, includes: initiating DC magnetron sputtering on the surface of the molybdenum disulfide / titanium gradient transition layer deposition, fixing the current of the titanium target and the molybdenum disulfide target to perform deposition, and obtaining the molybdenum disulfide / titanium functional layer.

6. The method according to claim 5, wherein, In step one, the ultrasonic cleaning includes: immersing the polished substrate in an ethanol solution and cleaning it for 10-15 minutes using an ultrasonic cleaning device; then immersing the substrate in an acetone solution and cleaning it for 10-15 minutes using an ultrasonic cleaning device.

7. The method according to claim 5, wherein, In step one, the glow discharge cleaning includes: clamping the ultrasonically cleaned substrate in the coating chamber and evacuating it to a vacuum level below 5 × 10⁻⁶. -3 After Pa, an inert gas is introduced at a flow rate of 30-80 sccm. The substrate bias voltage is adjusted to 120-150V, and the Hall ion source is turned on to perform argon ion glow discharge cleaning on the substrate for 30-60 minutes.

8. The method according to any one of claims 5 to 7, wherein, In step two, the deposition of the titanium transition layer includes: after glow discharge cleaning, disabling the Hall ion source, adjusting the flow rate of the inert gas, opening the front baffle of the titanium target, closing the front baffle of the molybdenum disulfide target, setting the titanium target current to 4-6 A, the deposition time to 1000-1500 s, and depositing the titanium transition layer using a DC magnetron sputtering process; and / or In step three, the titanium target current is reduced from 4-6 A to 0.6-3 A, the molybdenum disulfide target current is increased from 0 A to 4-6 A, and the deposition time is 400-800 s; and / or In step four, the titanium target current is 0.6-3A, the molybdenum disulfide target current is 4-6A, and the deposition time is 4-8h.

9. The method according to any one of claims 5 to 7, wherein, In steps two, three, and four, the DC bias voltage of the substrate is -50 to -60V, the inert gas flow rate is 18-20 sccm, the chamber pressure is 0.5-0.8 Pa, and the substrate temperature is 150-200℃; and / or In steps two, three, and four, the rotation speed of the deposition sample holder is 1-3 rpm; and / or The inert gas is argon.

10. The use of a titanium-doped molybdenum disulfide superlubricating film according to any one of claims 1 to 4 or a titanium-doped molybdenum disulfide superlubricating film prepared by any one of claims 5 to 9 as a solid lubricating material in aerospace, nuclear energy equipment or precision machinery in a vacuum; Optionally, the vacuum degree is 5×10 -3 Pa.

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