Molybdenum disulfide composite film and preparation method and application thereof

Abstract

The invention relates to a molybdenum disulfide composite film and a preparation method and application thereof. The molybdenum disulfide composite film comprises a titanium transition layer, a molybdenum disulfide / titanium / silver gradient transition layer and a molybdenum disulfide / titanium / silver multi-element structure layer which are sequentially formed on the surface of a base body. Wherein the multi-element structure layer comprises molybdenum disulfide, titanium nanoparticles and silver nanoparticles, and the titanium nanoparticles and the silver nanoparticles are distributed among molybdenum disulfide molecules; in the multi-element structure layer, the atom content of titanium is 4 at%-12 at%, the atom content of silver is 6 at%-20 at%, and the balance is molybdenum disulfide. The molybdenum disulfide composite film is suitable for vacuum wide-temperature-range extreme working conditions, stable lubrication is achieved in a wide temperature range, and the friction coefficient is not affected by temperature changes in the wide temperature range by regulating and controlling matching of the high-temperature solid lubricating coating.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of surface lubricating coating materials, in particular to a multi-doped molybdenum disulfide composite film suitable for extreme working conditions in a wide temperature range in vacuum and a preparation method and application thereof. BACKGROUND

[0002] Liquid lubricants are prone to thermal decomposition failure in high-temperature environments, especially when the temperature exceeds 350°C, making high-temperature solid lubrication technology the only viable solution to maintain the stable operation of such extreme working conditions of the friction interface. It is worth noting that high-temperature self-lubricating materials need to maintain functional properties in multiple coupled stress fields. Typical application scenarios include: high-temperature oxidation environment with chemical corrosion, interface shear effect of high-speed moving pairs, stress concentration caused by heavy load contact, and complex and severe working condition systems such as alternating exposure to atmosphere and vacuum under high-temperature conditions.

[0003] Molybdenum disulfide (MoS2) film has been successfully applied as a typical solid lubricant in aerospace, nuclear power equipment, and precision mechanical and electronic systems due to its low shear properties of layered structure. However, MoS2 film has significant environmental sensitivity and is prone to oxidation in atmospheric environments or high-temperature working conditions, leading to increased friction coefficient and performance degradation such as increased wear rate, which severely restricts its service life. For example, spacecraft moving parts need to withstand high humidity, high and low temperature alternation, and other extreme environments during storage, launch, and orbital operation, which poses a severe challenge to the chemical stability and mechanical reliability of MoS2 film. At the same time, the inherent hardness of MoS2 film is insufficient, which leads to interface peeling and wear failure under high-speed and heavy-load working conditions. Therefore, developing MoS2-based nanocomposite films with high hardness, excellent oxidation resistance, and wide temperature range stable lubrication properties has become a core technical requirement to ensure the long-term and reliable operation of key equipment such as aerospace transmission systems and nuclear reactor control mechanisms.

[0004] Elemental doping is an effective way to improve the high-temperature lubrication performance of MoS2 film. Existing invention patents disclose the use of doped tungsten disulfide, tungsten diboride, and soft metals such as gold and silver to improve the high-temperature tribological properties of molybdenum disulfide, for example: Chinese Patent 1: Application No. 202411898857.X, entitled "Use of Molybdenum Disulfide Composite Coating in Oxygen or Argon for Surface Protection of Nuclear Power Components", this patent is a molybdenum disulfide / silver coating, used in oxygen and argon environments, mainly for corrosion protection, but does not study its high-temperature application; Chinese patent 2: Application number 202411900696.3, invention name: Use of composite film with multi-element and multi-phase structure in high-temperature environment for lubrication of aerospace or nuclear power bearing surface. This patent prepares a molybdenum disulfide / tantalum / tungsten diboride coating, mainly used in high-temperature atmosphere, and the high temperature can only reach 400℃, and cannot reach higher temperature. The lubrication performance of this coating is general at room temperature, and the room temperature friction coefficient is 0.093; Chinese patent 3: Application number 202010486023.3, invention name: A molybdenum nitride / molybdenum disulfide / silver ternary composite high-temperature solid lubrication film and its preparation method. This patent prepares a molybdenum nitride / molybdenum disulfide / silver coating, mainly used in high-temperature atmosphere, and the friction coefficient is relatively high, between 0.1-0.2; Chinese patent 4: Application number 202210335728.4, invention name: A kind of metal doped molybdenum disulfide high-temperature resistant composite film and its preparation method. The coating structure of this patent is substrate-Cr transition layer-MoS-Cr-Ag layer, and this invention is also applied in high-temperature atmosphere; Chinese patent 5: Application number 202311162151.2, invention name: A kind of molybdenum disulfide / tungsten diboride nanocomposite multilayer film and its preparation method and application. The application condition of this patent is high-temperature atmosphere, and the high temperature can only reach 300℃.

[0005] From the above content, it can be seen that after doping the molybdenum disulfide coating alone, the friction coefficient at high temperature will increase with the increase of temperature, and finally fail at high temperature. Therefore, after modification and doping of the coating itself, the friction coefficient is still high, and the friction coefficient is greatly affected by temperature change. The existing modification and doping of molybdenum disulfide are mainly applied in corrosion environment and high-temperature atmosphere, and are not applied in vacuum high-temperature conditions. SUMMARY

[0006] The following is a summary of the subject matter of the detailed description of this document. This summary is not intended to limit the scope of protection of this application.

[0007] Therefore, based on the problems existing in the prior art, the present application provides a multi-element doped molybdenum disulfide composite film suitable for vacuum wide temperature range extreme working conditions and its preparation method, and a method for realizing stable lubrication in a wide temperature range, by adjusting the high-temperature solid lubrication coating pair, so that the friction coefficient is not affected by temperature change in a wide temperature range.

[0008] The first aspect of the present application provides a molybdenum disulfide composite film, which comprises a titanium transition layer, a gradient transition layer of molybdenum disulfide / titanium / silver and a multi-element structure layer of molybdenum disulfide / titanium / silver formed in sequence on the surface of a substrate.

[0009] In an exemplary embodiment, the element content in the gradient transition layer gradually changes from the titanium transition layer to the multi-element structure layer, and the multi-element structure layer comprises molybdenum disulfide, titanium nanoparticles and silver nanoparticles, and the titanium nanoparticles and silver nanoparticles are distributed between the molybdenum disulfide molecules.

[0010] In an exemplary embodiment, the particle size of the titanium nanoparticles and the silver nanoparticles in the multi-element structure layer ranges from 1 nm to 20 nm.

[0011] In an exemplary embodiment, the atomic content of titanium in the multi-element structure layer is 4 at% to 12 at% (for example, 4%, 6%, 8%, 10%, 12%, or any two values between the end values as a range value, but not limited to the listed values, and other unlisted values within the range of values are also applicable), the atomic content of silver is 6 at% to 20 at% (for example, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, or any two values between the end values as a range value, but not limited to the listed values, and other unlisted values within the range of values are also applicable), and the remaining component is molybdenum disulfide.

[0012] In an exemplary embodiment, the atomic content of titanium in the multi-element structure layer is 6 at% to 10 at%; preferably, the atomic content of titanium is 8 at% to 9 at%.

[0013] In an exemplary embodiment, the atomic content of silver in the multi-element structure layer is 6 at% to 18 at%; preferably, the content of silver is 8 at% to 15 at%; more preferably, the content of silver is 9 at% to 13 at%.

[0014] In an exemplary embodiment, the atomic content of titanium in the multi-element structure layer is 8 at%, the atomic content of silver is 6 at%, and the remaining component is molybdenum disulfide; or the atomic content of titanium is 8 at%, the atomic content of silver is 9 at%, and the remaining component is molybdenum disulfide; or the atomic content of titanium is 9 at%, the atomic content of silver is 13 at%, and the remaining component is molybdenum disulfide.

[0015] In an exemplary embodiment, in the gradient transition layer, the content of titanium gradually decreases to the same content as that in the multi-element structure layer, and the content of molybdenum disulfide and silver gradually increases to the same content as that in the multi-element structure layer, in the direction from the titanium transition layer to the multi-element structure layer.

[0016] In an exemplary embodiment, the total thickness of the molybdenum disulfide composite film is 4 μm to 11 μm.

[0017] In an exemplary embodiment, the thickness of the titanium transition layer is 50-500 nm.

[0018] In an exemplary embodiment, the thickness of the gradient transition layer is 200-500 nm.

[0019] In an exemplary embodiment, the thickness of the multi-element structure layer is 2-9 μm, for example, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or a range between any two of the values as end point values, but not limited to the listed values, other unlisted values within the range are also applicable.

[0020] In an exemplary embodiment, the total thickness of the molybdenum disulfide composite film is 4.07 μm, the thickness of the titanium transition layer is 0.50 μm, the thickness of the gradient transition layer is 0.2 μm, and the thickness of the multi-element structure layer is 3.37 μm; or the total thickness of the molybdenum disulfide composite film is 4.87 μm, the thickness of the titanium transition layer is 0.52 μm, the thickness of the gradient transition layer is 0.2 μm, and the thickness of the multi-element structure layer is 4.15 μm; or the total thickness of the molybdenum disulfide composite film is 7.16 μm, the thickness of the titanium transition layer is 0.6 μm, the thickness of the gradient transition layer is 0.2 μm, and the thickness of the multi-element structure layer is 6.36 μm.

[0021] In an exemplary embodiment, the material of the substrate includes any one or a combination of GCr15 steel, TC4 alloy, and 4169 high-temperature alloy.

[0022] In an exemplary embodiment, the molybdenum disulfide composite film has a friction coefficient less than 0.1 under a vacuum degree of 5×10 -3 Pa and a temperature of 25-450℃.

[0023] The second aspect of the present application provides a preparation method of the above-mentioned molybdenum disulfide composite film, comprising: starting a direct current magnetron sputtering power supply, and sequentially depositing a titanium transition layer, a gradient transition layer, and a multi-element structure layer on the surface of a substrate.

[0024] In an exemplary embodiment, the method uses a target material including two molybdenum disulfide targets, one silver target, and one titanium target. Different structures are deposited by controlling the opening and closing of the front baffle of the target material.

[0025] In an exemplary embodiment, the method specifically comprises the following steps: Step one, substrate surface treatment, comprising: ultrasonic cleaning the substrate after polishing and polishing processing, placing the cleaned substrate into a vacuum chamber of a multi-target magnetron sputtering device, introducing inert gas, and performing glow cleaning; Step two, titanium transition layer deposition, comprising: after completing the glow cleaning, adjusting the flow of inert gas, opening the front baffle of the titanium target, closing the front baffles of the silver target and the molybdenum disulfide target, setting the titanium target current value, and depositing a titanium transition layer by using a direct current magnetron sputtering process; Step three, gradient transition layer deposition, comprising: opening the front baffles of the titanium target, the silver target and the molybdenum disulfide target, gradually reducing the titanium target current, gradually increasing the molybdenum disulfide target and silver target current, and changing the current with time gradient to the target value to complete the gradient transition layer deposition; Step four, multi-element structure layer deposition, comprising: starting direct current magnetron sputtering on the surface of the gradient transition layer deposition, fixing the current of the titanium target, the silver target and the molybdenum disulfide target for deposition, and obtaining the molybdenum disulfide / titanium / silver multi-element structure layer.

[0026] In an exemplary embodiment, in step one, the ultrasonic cleaning comprises: immersing the substrate after polishing and polishing in an ethanol solution, cleaning for 10-15 minutes (for example, 10 minutes) by using an ultrasonic cleaning device, and then placing the substrate in an acetone solution and cleaning for 10-15 minutes (for example, 10 minutes) by using an ultrasonic cleaning device.

[0027] In an exemplary embodiment, in step one, the glow cleaning comprises: clamping the substrate in a coating chamber, vacuumizing to below 5x10 -3 Pa, introducing inert gas, the flow of the inert gas being 30-80 sccm (for example, 30 sccm), adjusting the substrate bias to 120-150 V (for example, 120 V), turning on the Hall ion source, and performing argon ion glow cleaning on the substrate for 30-60 minutes (for example, 30 minutes).

[0028] In one exemplary embodiment, in step two, the titanium transition layer deposition includes: after the glow cleaning is completed, the Hall ion source is deactivated, the flow rate of the inert gas is adjusted, the shutter in front of the titanium target is opened, the shutters in front of the silver target and the molybdenum disulfide target are closed, the titanium target current is set to 1-2 A (e.g., 1 A, 1.5 A, 2 A, or any two of the listed values as a range between the two, but not limited to the listed values, other unlisted values within the range are also acceptable), the substrate bias is set to -50 to -60 V (e.g., -50 V, -55 V, -60 V, or any two of the listed values as a range between the two, but not limited to the listed values, other unlisted values within the range are also acceptable), the inert gas flow rate is set to 18-20 seem (e.g., 18 seem, 19 seem, 20 seem, or any two of the listed values as a range between the two, but not limited to the listed values, other unlisted values within the range are also acceptable), the chamber pressure is set to 0.5-0.8 Pa (e.g., 0.5 Pa, 0.6 Pa, 0.7 Pa, 0.8 Pa, or any two of the listed values as a range between the two, but not limited to the listed values, other unlisted values within the range are also acceptable), the substrate temperature is set to 150-200 °C (e.g., 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, or any two of the listed values as a range between the two, but not limited to the listed values, other unlisted values within the range are also acceptable), and the deposition time is set to 1000-1500 s (e.g., 1000 s, 1100 s, 1200 s, 1300 s, 1400 s, 1500 s, or any two of the listed values as a range between the two, but not limited to the listed values, other unlisted values within the range are also acceptable), and a direct current magnetron sputtering process is used to deposit the titanium transition layer.

[0029] In an exemplary embodiment, in step three, the gradient transition layer is deposited by: opening the shutter in front of the titanium target, the silver target and the molybdenum disulfide target, reducing the titanium target current from 1-2 A to 0.1-0.3 A (e.g., 0.1, 0.2, 0.3, or any two of these values as a range between the endpoints, but not limited to the listed values, other unlisted values within the range are also acceptable), increasing the molybdenum disulfide target current from 0 A to 1-2 A (e.g., 1 A, 1.5 A, 2 A, or any two of these values as a range between the endpoints, but not limited to the listed values, other unlisted values within the range are also acceptable), increasing the silver target current from 0 A to 0.2-0.6 A (e.g., 0.2-0.3 A, 0.3-0.4 A, 0.4-0.5 A, 0.5-0.6 A, or any two of these values as a range between the endpoints, but not limited to the listed values, other unlisted values within the range are also acceptable), a deposition time of 400-800 s (e.g., 400 s, 600 s, 800 s, or any two of these values as a range between the endpoints, but not limited to the listed values, other unlisted values within the range are also acceptable), a substrate bias of -50 to -60 V, an inert gas flow of 18-20 seem, a chamber pressure of 0.5-0.8 Pa, and a substrate temperature of 150-200 °C.

[0030] In an exemplary embodiment, in step four, the multi-element structure layer is deposited by: starting direct current magnetron sputtering on the gradient transition layer deposition surface, fixing the titanium target current at 0.1-0.3 A (e.g., 0.1, 0.2, 0.3, or any two of these values as a range between the endpoints, but not limited to the listed values, other unlisted values within the range are also acceptable), the silver target current at 0.2-0.6 A (e.g., 0.2-0.3 A, 0.3-0.4 A, 0.4-0.5 A, 0.5-0.6 A, or any two of these values as a range between the endpoints, but not limited to the listed values, other unlisted values within the range are also acceptable), and the molybdenum disulfide target current at 1-2 A (e.g., 1 A, 1.5 A, 2 A, or any two of these values as a range between the endpoints, but not limited to the listed values, other unlisted values within the range are also acceptable), a deposition time of 4-8 h (e.g., 4 h, 6 h, 8 h, or any two of these values as a range between the endpoints, but not limited to the listed values, other unlisted values within the range are also acceptable), a substrate bias of -50 to -60 V, an inert gas flow of 18-20 seem, a chamber pressure of 0.5-0.8 Pa, and a substrate temperature of 150-200 °C.

[0031] In an exemplary embodiment, the rotation speed of the sample holder in steps two to four is 1-3 rpm (for example, 1 rpm, 2 rpm, 3 rpm or any two values between them as a range, but not limited to the listed values, other values not listed in the range are also applicable).

[0032] In an exemplary embodiment, the inert gas is argon.

[0033] The principle of preparing the multi-doped molybdenum disulfide film in the application is as follows: a direct current magnetron sputtering technology is used, the ratio of molybdenum disulfide, titanium and silver in the film is controlled by controlling the size of the current of various targets, titanium and silver are added in the form of nanoparticles between the molecular layers of molybdenum disulfide, and at the same time, the mechanism that silver can diffuse to the surface of the film at high temperature is used to improve the high temperature tribological properties of the film.

[0034] The third aspect of the application provides a molybdenum disulfide composite film prepared by the above method.

[0035] The fourth aspect of the application provides a use of the above-mentioned molybdenum disulfide composite film as a solid lubricating material in aerospace, nuclear power equipment or precision mechanical and electronic systems.

[0036] The fifth aspect of the application provides a method for realizing stable lubrication in a vacuum wide temperature range extreme working condition environment by using the above-mentioned molybdenum disulfide composite film.

[0037] Compared with the prior art, the application has the following technical effects: 1) The molybdenum disulfide composite film of the application is a silver-titanium co-doped molybdenum disulfide composite film; 2) The molybdenum disulfide composite film of the application is mainly applied to a vacuum high temperature environment (the vacuum degree is 5x10 -3 Pa, the highest working temperature is 450), the friction coefficient in a vacuum room temperature to high temperature wide temperature range (25-450℃) is less than 0.1, and it has a lubricating function in a wide temperature range; and the friction coefficient at room temperature is less than 0.02 or even can reach an ultra-smooth state (friction coefficient less than 0.01); 3) The molybdenum disulfide composite film of the application adopts a titanium transition layer, a MoS2 / Ti / Ag gradient transition layer and a MoS2 / Ti / Ag multi-element structure layer, and the film-substrate adhesion of the coating is more excellent.

[0038] In summary, the molybdenum disulfide composite film of the application is a silver and titanium co-doped molybdenum disulfide film. The friction performance test is carried out in a vacuum wide temperature range environment. The test results show that the friction coefficient of the film is less than 0.02 at room temperature, and even can reach the super-slip state (friction coefficient less than 0.01). The friction coefficient is less than 0.1 in a wide temperature range (25-450°C), and the film has a lubricating function in a wide temperature range.

[0039] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. Other advantages of the present application can be realized and attained by means of the instrumentalities and combinations particularly pointed out in the description and appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0040] The accompanying drawings are included to provide an understanding of the present application, and constitute a part of the specification, together with the embodiments of the present application, to explain the technical scheme of the present application, and do not constitute a limitation on the technical scheme of the present application.

[0041] Figure 1 AFM surface scan image of the multi-doped molybdenum disulfide composite film prepared for Example 1; Figure 2 Cross-sectional SEM image of the multi-doped molybdenum disulfide composite film prepared for Example 1; Figure 3 Friction coefficient curve of the multi-doped molybdenum disulfide composite film prepared for Example 1 under vacuum wide temperature range (25-450°C) conditions; Figure 4 Friction coefficient curve of the molybdenum disulfide composite film prepared for Comparative Example 1 under vacuum wide temperature range (25-450°C) conditions; Figure 5 Friction coefficient curve of the molybdenum disulfide composite film prepared for Comparative Example 2 at high temperature. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the present application more clear and apparent, the embodiments of the present application will be described in detail in the following. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other arbitrarily without conflict.

[0043] The present application will be further described in detail below in combination with specific embodiments, but the embodiments should not be understood as a limitation on the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts, all belong to the scope of protection of the present application.

[0044] Friction test: A reciprocating ball-on-disc friction and wear tester was used. The test was carried out at a load of 5x10-3 Pa vacuum environment, wide temperature range (25-450℃), the ball against the film of the example and the comparative example is Φ6mm GCr15 steel ball, the load is 5N, the sliding stroke is 4mm, the frequency is 4Hz, the sampling frequency is 120Hz. Obtain the friction coefficient curve with time.

[0045] Example 1 The preparation method of the multi-doped molybdenum disulfide composite film of the embodiment is as follows: Step one, substrate surface treatment, the material of the substrate is selected as 4169 high-temperature alloy, the polished and polished substrate is immersed in ethanol solution, ultrasonic cleaning equipment is used for ultrasonic cleaning for 10 minutes, then the substrate is immersed in acetone solution, ultrasonic cleaning equipment is used for ultrasonic cleaning for 10 minutes; The substrate after ultrasonic cleaning is clamped in the film plating chamber, the film plating chamber is vacuumed to less than 5x10 -3 Pa, then argon gas is introduced, the flow rate of argon gas is 30sccm, the substrate bias is adjusted to 120V, the Hall ion source is opened, and the substrate is subjected to 30 minutes of argon ion glow cleaning; Step two, titanium transition layer deposition, after completing the argon ion glow cleaning, the Hall ion source is disabled, argon gas is introduced into the vacuum chamber at a rate of 18sccm, the front baffle of the titanium target is opened, the front baffles of the silver target and the molybdenum disulfide target are closed, the titanium target current value is set to 1A, the substrate bias is-50V, the chamber pressure is 0.5 Pa, and the substrate temperature is 150℃. A titanium transition layer is deposited by direct current magnetron sputtering process, and the titanium transition layer is formed after 1000s of deposition time. Step three, molybdenum disulfide / titanium / silver gradient transition layer deposition, the front baffles of the titanium target, the silver target and the molybdenum disulfide target are opened, within 600s, the titanium target current is reduced from 1A to 0.3A, the molybdenum disulfide target current is increased from 0A to 2A, and the silver target current is increased from 0A to 0.2A. The current changes with time in a gradient within 600s to the required value of the multi-element structure layer, the gradient transition layer deposition is completed, the substrate bias is-50V, the inert gas flow rate is 18sccm, the substrate temperature is 150℃, and the chamber pressure is 0.5 Pa. Step four, molybdenum disulfide / titanium / silver multi-element structure layer deposition, direct current magnetron sputtering is started on the surface of the molybdenum disulfide / titanium / silver gradient transition layer deposition, the titanium target current is fixed at 0.3A, the silver target current is fixed at 0.2A, and the molybdenum disulfide target current is fixed at 2A. The substrate bias is-50V, the inert gas flow rate is 18sccm, the substrate temperature is 150℃, and the chamber pressure is 0.5 Pa. After 6h of deposition, the multi-doped molybdenum disulfide composite film suitable for vacuum wide temperature range extreme working conditions is prepared.

[0046] In steps two, three and four, the deposition workpiece holder rotation speed is 2rpm.

[0047] In Example 1, the multi-doped molybdenum disulfide composite film was detected, and the atomic content of silver in the multi-structure layer was 6 at%, and the atomic content of titanium was 8 at%; see Figure 2 , the total thickness of the multi-doped molybdenum disulfide composite film was 4.07 μm, the thickness of the titanium transition layer was 0.50 μm, the thickness of the gradient transition layer was 0.2 μm, and the thickness of the multi-structure layer was 3.37 μm; the particle size of the titanium nanoparticles and silver nanoparticles in the multi-structure layer was 1 nm.

[0048] Friction test: see Figure 3 It can be seen that the friction coefficient of the molybdenum disulfide composite film is less than 0.08, and the wear rate is less than 5×10 -3 mm -7 / Nm under the vacuum degree of 5×10 3 Pa and the temperature of 25-450℃.

[0049] Example 2 The preparation method of the multi-doped molybdenum disulfide composite film of the present embodiment is as follows: Step one, surface treatment of the substrate, the material of the substrate is selected as 4169 high-temperature alloy, the polished and polished substrate is soaked in ethanol solution, ultrasonic cleaning equipment is used for ultrasonic cleaning for 10 minutes, and then the substrate is soaked in acetone solution, ultrasonic cleaning equipment is used for ultrasonic cleaning for 10 minutes; the ultrasonic cleaned substrate is clamped in a film plating chamber, the film plating chamber is vacuumed to below 5×10 -3 Pa, then argon gas is introduced, the flow rate of argon gas is 30 sccm, the substrate bias is adjusted to 120V, the Hall ion source is turned on, and the substrate is subjected to 30 minutes of argon ion glow cleaning; Step two, titanium transition layer deposition, after completing the argon ion glow cleaning, the Hall ion source is disabled, argon gas is introduced into the vacuum chamber at a rate of 18 sccm, the front baffle of the titanium target is opened, the front baffles of the silver target and the molybdenum disulfide target are closed, the titanium target current value is set to 1A, the substrate bias is -50V, the inert gas flow rate is 18 sccm, the substrate temperature is 150℃, the chamber pressure is 0.5 Pa, and the titanium transition layer is deposited by direct current magnetron sputtering process, and the titanium transition layer is generated after 1000s of deposition time; Step three, deposition of the molybdenum disulfide / titanium / silver gradient transition layer, open the front shield of the titanium target, the silver target and the molybdenum disulfide target, within 600s, reduce the titanium target current from 1A to 0.3A, increase the molybdenum disulfide target current from 0A to 2A, increase the silver target current from 0A to 0.4A, the substrate bias is -50V, the inert gas flow is 18sccm, the substrate temperature is 150℃, the chamber pressure is 0.5 Pa, the current is time-gradient to the required value of the multi-element structure layer within 600s, and the deposition of the gradient transition layer is completed; Step four, deposition of the molybdenum disulfide / titanium / silver multi-element structure layer, start direct current magnetron sputtering on the surface of the molybdenum disulfide / titanium / silver gradient transition layer, fix the titanium target current at 0.3A, fix the silver target current at 0.4A, fix the molybdenum disulfide target current at 2A, the substrate bias is -50V, the inert gas flow is 18sccm, the substrate temperature is 150℃, the chamber pressure is 0.5 Pa, and the multi-element doped molybdenum disulfide film suitable for vacuum wide temperature range extreme working conditions is prepared after 6h of deposition.

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

[0051] In example 2, the multi-element doped molybdenum disulfide composite film is detected, the atomic content of silver in the multi-element structure layer is 9 at%, the atomic content of titanium is 8 at%, the total thickness of the multi-element doped molybdenum disulfide film is 4.87 μm, the thickness of the titanium transition layer is 0.52 μm, the thickness of the molybdenum disulfide / titanium / silver gradient transition layer is 0.2 μm, and the thickness of the multi-element structure layer is 4.15 μm; the particle size of titanium nanoparticles and silver nanoparticles in the multi-element structure layer is 5nm.

[0052] Friction test: the friction coefficient of the molybdenum disulfide composite film is 0.0087, 0.02914, 0.04503, 0.05509 and 0.07081 respectively under vacuum degree of 5×10 -3 Pa, temperature of 25℃, 150℃, 250℃, 350℃ and 450℃.

[0053] Example 3 The preparation method of the multi-element doped molybdenum disulfide composite film of the present example is as follows: Step one, substrate surface treatment, the material of the substrate is selected as 4169 high-temperature alloy, the polished and polished substrate is soaked in ethanol solution, ultrasonic cleaning equipment is used for ultrasonic cleaning for 10 minutes, and then the substrate is soaked in acetone solution, ultrasonic cleaning equipment is used for ultrasonic cleaning for 10 minutes; the ultrasonic cleaned substrate is clamped in a plating film chamber, the plating film chamber is vacuumed to below 5×10 -3After Pa, argon gas is introduced again, the flow rate of argon gas is 30 sccm, the substrate bias is adjusted to 120 V, the Hall ion source is turned on, and the substrate is subjected to argon ion glow cleaning for 30 minutes; Step two, titanium transition layer deposition: after the argon ion glow cleaning is completed, the Hall ion source is turned off, argon gas is introduced into the vacuum chamber at a rate of 18 sccm, the front baffle of the titanium target is opened, the front baffles of the silver target and the molybdenum disulfide target are closed, the titanium target current value is set to 1 A, the substrate bias is -50 V, the substrate temperature is 150℃, the chamber pressure is 0.5 Pa, the titanium transition layer is deposited by using a direct current magnetron sputtering process, and the titanium transition layer is generated after a deposition time of 1000 s; Step three, molybdenum disulfide / titanium / silver gradient transition layer deposition: the front baffles of the titanium target, the silver target and the molybdenum disulfide target are opened, within 600 s, the titanium target current is reduced from 1 A to 0.3 A, the molybdenum disulfide target current is increased from 0 A to 2 A, the silver target current is increased from 0 A to 0.6 A, the substrate bias is -50 V, the inert gas flow rate is 18 sccm, the substrate temperature is 150℃, the chamber pressure is 0.5 Pa, and the current is changed with time within 600 s to the required value of the multi-element structure layer, and the gradient transition layer deposition is completed; Step four, molybdenum disulfide / titanium / silver multi-element structure layer deposition: the direct current magnetron sputtering is started on the surface of the molybdenum disulfide / titanium / silver gradient transition layer, the titanium target current is fixed at 0.3 A, the silver target current is fixed at 0.6 A, the molybdenum disulfide target current is fixed at 2 A, the substrate bias is -50 V, the inert gas flow rate is 18 sccm, the substrate temperature is 150℃, the chamber pressure is 0.5 Pa, and after 6 h of deposition, the multi-element doped molybdenum disulfide film suitable for vacuum wide temperature range extreme working conditions is prepared.

[0054] In steps two, three and four, the deposition workpiece holder rotation speed is 2 rpm.

[0055] In example 3, the multi-element doped molybdenum disulfide composite film is detected, the atomic content of silver in the multi-element structure layer is 13 at%, the atomic content of titanium is 9 at%, the total thickness of the multi-element doped molybdenum disulfide film is 7.16 μm, the thickness of the titanium transition layer is 0.6 μm, the thickness of the molybdenum disulfide / titanium / silver gradient transition layer is 0.2 μm, and the thickness of the multi-element structure layer is 6.36 μm; the particle size of the titanium nanoparticles and the silver nanoparticles in the multi-element structure layer is 20 nm.

[0056] Friction test: the friction coefficient of the molybdenum disulfide composite film is 0.01132, 0.0247, 0.04497, 0.0584 and 0.09011 respectively under vacuum degrees of 5×10 -3 Pa, temperatures of 25℃, 150℃, 250℃, 350℃ and 450℃.

[0057] Comparative Example 1 The preparation process of the multi-doped molybdenum disulfide composite film in Comparative Example 1 is basically similar to that of Example 1, and the difference is that: In step three, only the front baffles of the titanium target and the molybdenum disulfide target were opened, and within 600 s, the titanium target current was reduced from 1 A to 0.2 A, the molybdenum disulfide target current was increased from 0 A to 2 A, the substrate bias was -50 V, the inert gas flow was 18 sccm, the substrate temperature was 150°C, the chamber pressure was 0.5 Pa, and the current was changed with time gradient to the required value of the multi-structure layer within 600 s to complete the deposition of the gradient transition layer. In step four, the deposition of the molybdenum disulfide / titanium multi-structure layer was carried out, and the direct current magnetron sputtering was started on the surface of the molybdenum disulfide / titanium gradient transition layer. The titanium target current was fixed at 0.6 A, the silver target current was fixed at 0 A, the molybdenum disulfide target current was fixed at 2 A, the substrate bias was -50 V, the inert gas flow was 18 sccm, and the substrate temperature was 150°C. After 6 h of deposition, Comparative Example 1 was prepared.

[0058] Friction test: as shown in Figure 4 The friction coefficient of Comparative Example 1 was less than 0.02 at a vacuum degree of 5x10 -3 Pa and a temperature of 25°C, and it directly failed in the high-temperature experiment at 150-450°C.

[0059] Comparative Example 2 The difference between the preparation method of the multi-doped molybdenum disulfide composite film in this comparative example and Example 1 is that: In step four, the titanium target current was fixed at 0.8 A, the silver target current was fixed at 0.1 A, and the molybdenum disulfide target current was fixed at 1.6 A for deposition to obtain a multi-doped molybdenum disulfide composite film.

[0060] Friction test: see Figure 5 The high-temperature friction coefficient of the composite film in Comparative Example 2 was not good, and the friction coefficient reached 0.2 in the lubrication stage when the friction experiment was carried out at 450°C, which was much higher than the friction coefficient of Example 1 at 450°C. The lubrication life of Comparative Example 2 at 450°C was only 500 revolutions, which was much lower than the 8000 revolutions of Example 1.

[0061] Therefore, when the current value of the titanium target is greater than 0.3 A or the current value of the silver target is less than 0.2 A, it will cause the titanium content in the multi-structure layer to be too high or the silver content to be too low, the friction effect of the multi-structure layer in the composite film will be poor, and the lubrication life will also be affected.

[0062] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and that changes, modifications, substitutions and variations can be made by those skilled in the art without departing from the scope of the present application.

Claims

1. A molybdenum disulfide composite thin film, comprising a titanium transition layer, a molybdenum disulfide / titanium / silver gradient transition layer, and a molybdenum disulfide / titanium / silver multi-element structure layer sequentially formed on a substrate surface; wherein, The multi-component structure layer includes molybdenum disulfide, titanium nanoparticles, and silver nanoparticles. The titanium nanoparticles and the silver nanoparticles are distributed between molybdenum disulfide molecules, and the particle size range of the titanium nanoparticles and the silver nanoparticles is 1-20 nm. In the multi-component structure layer, the atomic content of titanium is 4at%-12at, the atomic content of silver is 6at%-20at, and the remaining component is molybdenum disulfide.

2. The molybdenum disulfide composite film according to claim 1, wherein, The total thickness of the molybdenum disulfide composite film is 4-11 μm; and / or The thickness of the titanium transition layer is 50-500 nm; and / or The thickness of the gradient transition layer is 200-500 nm; and / or The thickness of the multi-component structural layer is 2-9 μm.

3. The molybdenum disulfide composite film according to claim 1 or 2, wherein, The substrate material includes any one or a combination of GCr15 steel, TC4 alloy, and 4169 high-temperature alloy.

4. The molybdenum disulfide composite film according to claim 1 or 2, wherein, The molybdenum disulfide composite film was subjected to a vacuum degree of 5×10⁻⁶. -3 Pa, the coefficient of friction is less than 0.1 in an environment with a temperature of 25-450℃.

5. A method for preparing a molybdenum disulfide composite thin film according to any one of claims 1 to 4, wherein the target material used in the method comprises two molybdenum disulfide targets, one silver target, and one titanium target; the method comprises 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 baffles of the silver target and the molybdenum disulfide target, setting the titanium target current value, and depositing the titanium transition layer using a DC magnetron sputtering process. Step 3, gradient transition layer deposition, includes: opening the front baffles of the titanium target, the silver target and the molybdenum disulfide target, gradually reducing the current of the titanium target, gradually increasing the current of the molybdenum disulfide target and the silver target, and changing the current with time gradient to the target value to complete the gradient transition layer deposition; Step four, deposition of the multi-element structure layer, includes: initiating DC magnetron sputtering on the deposition surface of the gradient transition layer, fixing the current of the titanium target, the silver target and the molybdenum disulfide target to deposit the multi-element structure 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 using an ultrasonic cleaning device for 10-15 minutes; then immersing the substrate in an acetone solution and cleaning it using an ultrasonic cleaning device for 10-15 minutes; and / or In step one, the glow discharge cleaning includes: clamping the substrate in the coating chamber and evacuating the vacuum to below 5 × 10⁻⁶. -3 After Pa, the inert gas is introduced at a flow rate of 30-80 sccm. The substrate bias voltage is adjusted to 120-150V, the Hall ion source is turned on, and the substrate is subjected to argon ion glow discharge cleaning for 30-60 minutes.

7. The method according to any one of claims 5 to 6, 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 baffles of the silver target and the molybdenum disulfide target, setting the titanium target current to 1-2A, the substrate bias voltage to -50 to -60V, the inert gas flow rate to 18-20 sccm, the chamber pressure to 0.5-0.8 Pa, the substrate temperature to 150-200℃, and the deposition time to 1000-1500 s, using a DC magnetron sputtering process to deposit the titanium transition layer; and / or Step three involves gradient transition layer deposition, including: opening the front baffles of the titanium target, the silver target, and the molybdenum disulfide target; reducing the titanium target current from 1-2 A to 0.1-0.3 A; increasing the molybdenum disulfide target current from 0 A to 1-2 A; increasing the silver target current from 0 A to 0.2-0.6 A; and a deposition time of 400-800 s. The substrate bias voltage is -50 to -60 V, 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 °C; and / or In step four, the deposition of the multi-component structure layer includes: initiating DC magnetron sputtering on the deposition surface of the gradient transition layer, fixing the titanium target current at 0.1-0.3 A, the silver target current at 0.2-0.6 A, the molybdenum disulfide target current at 1-2 A, and the deposition time at 4-8 h; the substrate bias voltage is -50 to -60 V, 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 °C.

8. The method according to any one of claims 5 to 6, wherein, In steps two through four, the rotation speed of the deposition sample holder is 1-3 rpm; and / or The inert gas is argon.

9. The use of a molybdenum disulfide composite film according to any one of claims 1 to 4 or a molybdenum disulfide composite film prepared by any one of claims 5 to 8 as a solid lubricant in aerospace, nuclear power equipment or precision electromechanical systems.

10. A method for achieving stable lubrication of a molybdenum disulfide composite film prepared using any one of claims 1 to 4 or any one of claims 5 to 8 under extreme working conditions in a vacuum wide temperature range.

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