A lubricating film and its preparation method and application

Abstract

The present invention relates to the field of mechanical lubrication technology, and in particular to a lubricating film, a preparation method thereof, and an application thereof. The preparation method provided by the present invention comprises the following steps: subjecting a substrate to Ar ion bombardment treatment to obtain a pretreated substrate; and repeatedly depositing a MoS2 film and performing N plasma passivation treatment on the surface of the pretreated substrate to obtain the lubricating film. The preparation method of the present invention introduces a trace amount of N element to form a dangling bond passivation effect on S vacancies in the film, and the film has a nanocrystalline dense structure and good chemical stability. According to the description in the examples, the vacuum friction coefficient of the lubricating film provided by the present invention is lower than 0.03, and the lubrication life is higher than 5.0×10 5 r, and also has good lubrication performance under atmospheric conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical lubrication, and in particular to a lubricating film, a preparation method thereof, and an application thereof. Background Art

[0002] With the implementation of my country's lunar and deep space exploration programs, higher requirements are being placed on the lifespan and reliability of lubricating films. Spacecraft machinery and equipment are exposed to both the humid atmosphere and the vacuum environment of orbit during ground transportation, storage, and commissioning. Lubricating film materials with excellent adaptability to both terrestrial and astronomical environments are crucial for the long service life and highly reliable operation of aerospace motion mechanisms.

[0003] Transition metal dichalcogenides (MoS2, WS2, etc.) have excellent vacuum cold welding and lubrication properties. As a good solid lubricant, they have been widely used in various moving parts in aerospace structures as lubricating films on the substrate surface. However, thin films of transition metal dichalcogenides are easily oxidized in humid air environments, and the resulting oxides have a high molar coefficient. At the same time, they also form the reaction product H2SO4, which causes electrochemical corrosion and causes the lubricating film to peel off, greatly reducing the lubrication performance of the film and the life of the moving parts. One of the main reasons for the poor environmental sensitivity of dichalcogenide films is that the sputtered films are prone to forming a high density of dangling bonds due to the loss of S elements during the deposition process. The high activity of the dangling bonds formed by a large number of S vacancies makes them susceptible to oxidation corrosion, resulting in a significant decrease in their tribological properties. Summary of the Invention

[0004] The object of the present invention is to provide a lubricating film and a preparation method and application thereof. The lubricating film prepared by the preparation method has a nanocrystalline dense structure and has good chemical stability and tribological properties.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a lubricating film, comprising the following steps:

[0007] The substrate is subjected to Ar ion bombardment treatment to obtain a pretreated substrate;

[0008] The lubricating film is obtained by repeatedly cyclically depositing a MoS2 film and performing a N plasma passivation treatment on the pretreated substrate surface.

[0009] Preferably, the substrate comprises stainless steel or titanium alloy.

[0010] Preferably, the working gas for the Ar ion bombardment treatment is argon, the pressure of the working gas is 1.0 to 3.0 Pa, the voltage is -200 to -300 V, and the time is 15 to 30 minutes.

[0011] Preferably, the method for depositing the MoS2 thin film is DC pulsed magnetron sputtering.

[0012] Preferably, the conditions of the DC pulse magnetron sputtering are: the vertical distance between the target and the substrate surface is 100-150 mm, the working gas is Ar, the working gas pressure is 1.0-2.0 Pa, the bias voltage is -10--60 V, and the sputtering power density is 1.8-2.6 W / cm 2 , time is 8 to 15 minutes;

[0013] The target material is a MoS2 target material.

[0014] Preferably, the working gases for the N plasma passivation treatment are nitrogen and argon, the gas pressure of the working gases is 0.3 to 0.8 Pa, the flow ratio of nitrogen to argon is 0.1 to 0.3, the auxiliary filament heating current is 180 A, the plasma source current is 30 to 60 A, the bias voltage is -50 to -200 V, and the time is 5 to 10 min.

[0015] Preferably, the number of repeated cycles is 6 to 15 times.

[0016] The present invention also provides a lubricating film prepared by the preparation method described in the above technical solution, wherein the lubricating film is a MoS2 lubricating film doped with N element.

[0017] Preferably, the atomic ratio of S to Mo in the lubricating film is (1.65-1.70):1, and the atomic ratio of N to Mo is (0.3-0.4):1;

[0018] The thickness of the lubricating film is 1.0 to 3.0 μm.

[0019] The present invention also provides the application of the lubricating film described in the above technical solution in the field of surface lubrication of mechanical components.

[0020] The present invention provides a method for preparing a lubricating film, comprising the following steps: subjecting a substrate to Ar ion bombardment to obtain a pretreated substrate; and repeatedly depositing a MoS2 film and performing a N plasma passivation treatment on the surface of the pretreated substrate to obtain the lubricating film. The preparation method of the present invention introduces a trace amount of nitrogen to create a dangling bond passivation effect on sulfur vacancies in the film, and the film exhibits a dense nanocrystalline structure and good chemical stability. According to the examples, the lubricating film provided by the present invention has a vacuum friction coefficient of less than 0.03 and a lubrication life of greater than 5.0×10 5 r, and also has good lubrication performance under atmospheric conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the structure of the pulsed DC magnetron sputtering and plasma source device;

[0022] Figure 2 Transmission electron microscopy and element distribution diagram of the MoS2 lubricating film treated with N element passivation as described in Example 1;

[0023] Figure 3 Friction test curves of the MoS2 lubricating film passivated with N element described in Example 1 and the pure MoS2 lubricating film described in Comparative Example 1 under vacuum and atmospheric conditions;

[0024] Figure 4 This is a Raman spectrum of wear debris generated by the MoS2 lubricating film passivated with N element described in Example 1 and the pure MoS2 lubricating film described in Comparative Example 1 after the life friction test under atmospheric conditions;

[0025] Figure 5 These are the vacuum friction test curves of the MoS2 lubricating film passivated with N element described in Example 2 and the pure MoS2 lubricating film described in Comparative Example 1. DETAILED DESCRIPTION

[0026] The present invention provides a method for preparing a lubricating film, comprising the following steps:

[0027] The substrate is subjected to Ar ion bombardment treatment to obtain a pretreated substrate;

[0028] The lubricating film is obtained by repeatedly cyclically depositing a MoS2 film and performing a N plasma passivation treatment on the pretreated substrate surface.

[0029] In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well known to those skilled in the art.

[0030] The present invention performs Ar ion bombardment treatment on the substrate to obtain a pretreated substrate.

[0031] In the present invention, the substrate preferably comprises stainless steel or titanium alloy. The present invention does not have any particular limitation on the specific composition of the stainless steel or titanium alloy, and any stainless steel or titanium alloy composition known to those skilled in the art can be used. In a specific embodiment of the present invention, the substrate is made of 9Cr18 steel.

[0032] Prior to the Ar ion bombardment treatment, the present invention also preferably includes sequential cleaning and drying; the cleaning is preferably performed by sequentially placing the substrate in acetone and anhydrous ethanol for ultrasonic cleaning for 15 minutes. The present invention does not have any particular restrictions on the frequency of the ultrasonic cleaning, and frequencies familiar to those skilled in the art can be used; the acetone is preferably analytical grade acetone. In the present invention, the drying method is preferably oven drying. The present invention does not have any particular restrictions on the drying process, and processes familiar to those skilled in the art can be used. In an embodiment of the present invention, the drying is specifically performed in an infrared oven.

[0033] In the present invention, the working gas for the Ar ion bombardment treatment is preferably argon, and the gas pressure of the working gas is preferably 1.0 to 3.0 Pa, more preferably 1.5 to 2.5 Pa, and most preferably 1.8 to 2.2 Pa; the voltage is preferably -200 to -300 V, more preferably -220 to -280 V, and most preferably -240 to -260 V; the time is preferably 15 to 30 min, more preferably 18 to 26 min, and most preferably 20 to 23 min.

[0034] In the present invention, the process of Ar ion bombardment treatment is preferably to place the substrate on a workpiece holder in a vacuum chamber, adjust the distance between the substrate and the sputtering target, and then evacuate the chamber to a background vacuum of ≤1.0×10 -3 After Pa, argon gas is filled, the workpiece holder is turned on to rotate, and Ar ion bombardment treatment is performed. In the present invention, the rotation speed of the workpiece holder in the vacuum chamber is preferably 2.0 r / min.

[0035] In the present invention, the Ar ion bombardment treatment is used to clean the surface of the substrate.

[0036] After obtaining the pretreated substrate, the present invention repeatedly deposits a MoS2 film and performs N plasma passivation treatment on the surface of the pretreated substrate to obtain the lubricating film.

[0037] In the present invention, the method for depositing MoS2 thin film is preferably DC pulse magnetron sputtering; the conditions of the DC pulse magnetron sputtering are preferably: the vertical distance between the target material and the substrate surface is preferably 100-150 mm, more preferably 110-140 mm, and most preferably 120-130 mm; the working gas is preferably Ar, and the gas pressure of the working gas is preferably 1.0-2.0 Pa, more preferably 1.2-1.8 Pa, and most preferably 1.4-1.6 Pa; the bias voltage is preferably -10--60 V, more preferably -20--50 V, and most preferably -30--40 V; the sputtering power density is preferably 1.8-2.6 W / cm 2 , more preferably 2.0 to 2.3 W / cm 2The time is preferably 8 to 15 minutes, more preferably 10 to 13 minutes. The target is preferably a MoS2 target. In the present invention, the size of the MoS2 target is preferably a rectangular target of 1000 mm*170 mm. The thickness of the MoS2 target is preferably 4 to 8 mm.

[0038] In the present invention, the thickness of the MoS2 film obtained after depositing the MoS2 film is preferably 100 to 300 nm, more preferably 150 to 250 nm, and most preferably 180 to 220 nm.

[0039] In the present invention, the working gases for the N plasma passivation treatment are preferably nitrogen and argon, and the gas pressure of the working gas is preferably 0.3-0.8 Pa, more preferably 0.4-0.7 Pa, and most preferably 0.5-0.6 Pa; the flow ratio of nitrogen to argon is preferably 0.1-0.3, more preferably 0.15-0.25, and most preferably 0.2; the auxiliary filament heating current is preferably 180 A; the plasma source current is preferably 30-60 A, more preferably 35-55 A, and most preferably 40-50 A; the bias voltage is preferably -50--200 V, more preferably -100--150 V; and the time is preferably 5-10 min, more preferably 6-8 min.

[0040] In the present invention, the number of repeated cycles is preferably 6 to 15 times, more preferably 9 to 12 times.

[0041] The present invention also provides a lubricating film prepared by the preparation method described in the above technical solution, wherein the lubricating film is a MoS2 lubricating film doped with N element.

[0042] In the present invention, the atomic ratio of S to Mo in the lubricating film is preferably (1.65-1.70):1, and the atomic ratio of N to Mo is preferably (0.3-0.4):1; the thickness of the lubricating film is preferably 1.0-3.0 μm, more preferably 1.2-2 μm.

[0043] In the present invention, the vacuum friction coefficient of the lubricating film is preferably ≤0.03, and the wear life is preferably >5.0×10 5 r; Under humid atmospheric conditions, the friction coefficient is preferably less than 0.15, and the lubrication life is preferably greater than 2.0×10 5 r.

[0044] In the present invention, a trace amount of N element is introduced into the film through periodic N plasma treatment, thereby forming a dangling bond passivation effect on S vacancies in the film, and the film presents a nanocrystalline dense structure and has good chemical stability.

[0045] The present invention also provides the application of the lubricating film described in the above technical solution in the field of surface lubrication of mechanical components. The present invention does not have any special limitation on the method of application, and the method well known to those skilled in the art can be used.

[0046] The lubricating film provided by the present invention, its preparation method and application are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0047] Example 1

[0048] 9Cr18 steel was ultrasonically cleaned in analytical grade acetone and anhydrous ethanol for 15 min each, dried in an infrared oven, and then placed on a vacuum strong workpiece holder. The vertical distance between the substrate and the sputtering target surface was adjusted to 150 mm. The vacuum chamber was evacuated. When the background vacuum was better than 1.0×10 -3 After Pa, argon gas was filled into the vacuum chamber with a pressure of 2.0 Pa, the workpiece holder was turned on with a rotation speed of 2.0 r / min, a bias voltage of -200 V, and Ar ion bombardment for 20 min;

[0049] In such Figure 1 In the device, the Ar gas flow rate is adjusted, the gas pressure is adjusted to 1.5 Pa, the bias voltage is added to -30 V, the DC pulse sputtering power supply is turned on, the sputtering power of the MoS2 target is set to 4 kW, and after 10 minutes of film deposition, the sputtering is stopped, N2 is introduced into the chamber, the N2 to Ar flow ratio is adjusted to 1:6, the gas pressure is controlled to 0.5 Pa, the auxiliary filament heating current is 180 A, the plasma source current is 30 A, the bias voltage is -50 V, and the plasma treatment time is 5 minutes. After that, the above-mentioned film deposition and N plasma treatment process are repeated, and 6 cycles of film preparation are completed cumulatively to obtain a MoS2 lubricating film with N element passivation treatment (thickness is 1.41 μm, and the atomic content ratio of the components in the film is S / Mo is 1.68, and N / Mo is 0.36).

[0050] Example 2

[0051] 9Cr18 steel was ultrasonically cleaned in analytical grade acetone and anhydrous ethanol for 15 min each, dried in an infrared oven, and then placed on a vacuum strong workpiece holder. The vertical distance between the substrate and the sputtering target surface was adjusted to 150 mm. The vacuum chamber was evacuated. When the background vacuum was better than 1.0×10 -3 After Pa, argon gas was filled into the vacuum chamber with a pressure of 2.0 Pa, the workpiece holder was turned on with a rotation speed of 2.0 r / min, a bias voltage of -200 V, and Ar ion bombardment for 20 min;

[0052] In such Figure 1In the device, the Ar gas flow rate was adjusted, the gas pressure was adjusted to 1.5 Pa, the bias voltage was increased to -30 V, the DC pulse sputtering power was turned on, and the sputtering power of the MoS2 target was set to 4 kW (2.35 W / cm 2 ), after 5 minutes of film deposition, sputtering was stopped, N2 was introduced into the chamber, the flow ratio of N2 to Ar was adjusted to 1:6, the gas pressure was controlled to 0.5 Pa, the auxiliary filament heating current was 180 A, the plasma source current was 30 A, the bias voltage was -50 V, and the plasma treatment time was 5 minutes. The above film deposition and N plasma treatment processes were repeated, and 13 cycles of film preparation were completed to obtain a MoS2 lubricating film with N element passivation treatment (with a thickness of 1.50 μm and a component atomic content ratio of S / Mo of 1.66 and N / Mo of 0.39 in the film).

[0053] Comparative Example 1

[0054] 9Cr18 steel was ultrasonically cleaned in analytical grade acetone and anhydrous ethanol for 15 min each, dried in an infrared oven, and then placed on a vacuum strong workpiece holder. The vertical distance between the substrate and the sputtering target (MoS2 target) was adjusted to 150 mm. The vacuum chamber was evacuated. When the background vacuum was better than 1.0×10 -3 After 1.5 Pa, argon gas was filled into the vacuum chamber with a pressure of 0.8 Pa, the workpiece holder was turned on with a rotation speed of 2.0 r / min, a bias voltage of -200 V, and Ar ion bombardment for 20 min;

[0055] Adjust the Ar gas flow rate, the gas pressure to 1.5 Pa, the bias voltage to -30 V, turn on the DC pulse sputtering power, and set the sputtering power of the MoS2 target to 4 kW (2.35 W / cm 2 ), the film was deposited for 60 min to obtain a pure MoS2 lubricating film (thickness of 1.52 μm, the atomic content ratio of the components in the film was S / Mo was 1.68, and there was no N element).

[0056] Test Case

[0057] The MoS2 lubricating films passivated with nitrogen elements described in Examples 1 and 2 and the pure MoS2 lubricating film described in Comparative Example 1 were subjected to TEM testing, element content testing, and friction testing (referring to the GJB3032-97 standard, i.e., a ball-disc friction test apparatus was used to assess the friction coefficient and wear life of the films. The test conditions were: room temperature, a normal load of 5.00 N, a turntable speed of (1000 ± 2) r / min, and a Φ8 mm 9Cr18 steel ball as the pair; the test environment included vacuum conditions (the vacuum degree was better than 1.0 × 10 -3 Pa) and atmospheric environment (~40RH%)), the test results are as follows Figures 2-4 As shown;

[0058] in, Figure 2 The transmission electron microscope and element distribution diagram of the MoS2 lubricating film treated with N element passivation in Example 1 are shown in FIG. Figure 2 It can be seen that the MoS2 lubricating film passivated with nitrogen element in Example 1 is a dense nanocrystalline structure, and trace nitrogen elements are evenly distributed inside the film;

[0059] Figure 3 The friction test curves of the MoS2 lubricating film passivated with N element in Example 1 and the pure MoS2 lubricating film in Comparative Example 1 under vacuum and atmospheric conditions are shown in FIG. Figure 3 It can be seen that under vacuum conditions, the average friction coefficient of pure MoS2 film is about 0.035, and the wear life is less than 1.5×10 5 r, while the lubrication life of the MoS2 lubricating film treated with nitrogen element passivation is higher than 2.0×10 5 r;

[0060] Figure 4 The Raman spectra of wear debris generated by the MoS2 lubricating film with N element passivation treatment described in Example 1 and the pure MoS2 lubricating film described in Comparative Example 1 after the life friction test under atmospheric conditions are shown. The Raman spectra of wear debris generated by the pure MoS2 film after the friction life test under atmospheric conditions are shown. The Raman spectra of wear debris generated by the pure MoS2 film after the friction life test under atmospheric conditions are shown. -1 and 406cm -1 The Raman scattering peak intensity of MoS2 at the surface is very weak, while a strong Raman scattering peak of MoO3 appears, indicating that the pure MoS2 film of Comparative Example 1 has undergone significant oxidation during the friction process under atmospheric conditions; while the wear debris of the MoS2-based lubricating film passivated with N element as described in Example 1 after the friction test is mainly composed of the Raman scattering peak of MoS2, and no obvious Raman scattering peak of molybdenum oxide appears;

[0061] Figure 5 The vacuum friction test curves of the MoS2 lubricating film treated with N element passivation in Example 2 and the pure MoS2 lubricating film in Comparative Example 1 are shown; Figure 5 It can be seen that the average friction coefficient of the MoS2 lubricating film treated with N element passivation in Example 2 is 0.02, which is significantly lower than that of the pure MoS2 lubricating film in Comparative Example 1, and the lubrication life is significantly longer than that in Comparative Example 1.

[0062] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the original invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a lubricating film, characterized in that: The following steps are involved: The substrate is subjected to Ar ion bombardment treatment to obtain a pretreated substrate; Repeatedly depositing a MoS2 film and performing a N plasma passivation treatment on the pretreated substrate surface to obtain the lubricating film; The thickness of the MoS2 film obtained after the MoS2 film is deposited is 100 to 300 nm; The working gases for the N plasma passivation treatment are nitrogen and argon, the working gas pressure is 0.3-0.8 Pa, the flow ratio of nitrogen to argon is 0.1-0.3, the auxiliary filament heating current is 180 A, the plasma source current is 30-60 A, the bias voltage is -50--200 V, and the time is 5-10 min; The lubricating film is a MoS2 lubricating film doped with N element, and the atomic ratio of S to Mo in the lubricating film is (1.65-1.70):

1.

2. The preparation method according to claim 1, wherein The substrate comprises stainless steel or titanium alloy.

3. The preparation method according to claim 1, wherein The working gas for the Ar ion bombardment treatment is argon gas, the pressure of the working gas is 1.0 to 3.0 Pa, the voltage is -200 to -300 V, and the time is 15 to 30 minutes.

4. The preparation method according to claim 1, wherein The method for depositing the MoS2 film is direct current pulse magnetron sputtering.

5. The preparation method according to claim 4, wherein The conditions of the DC pulse magnetron sputtering are as follows: the vertical distance between the target and the substrate surface is 100-150 mm, the working gas is Ar, the working gas pressure is 1.0-2.0 Pa, the bias voltage is -10--60 V, and the sputtering power density is 1.8-2.6 W / cm 2 , time is 8 to 15 minutes; The target material is a MoS2 target material.

6. The preparation method according to any one of claims 1, 4 to 5, characterized in that: The number of repeated cycles is 6 to 15 times.

7. The lubricating film prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The lubricating film is a MoS2 lubricating film doped with N element.

8. The lubricating film according to claim 7, wherein: The atomic ratio of N to Mo in the lubricating film is (0.3-0.4):1; The thickness of the lubricating film is 1.0 to 3.0 μm.

9. Use of the lubricating film according to claim 7 or 8 in the field of surface lubrication of mechanical components.

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