NbB2-c-ag wide-temperature-range lubricating film material and preparation method thereof

Abstract

The application discloses a NbB2-C-Ag wide-temperature-range lubricating thin film material and a preparation method thereof. The thin film material comprises amorphous C, nanocrystalline NbB2 and Ag, wherein the amorphous C wraps the nanocrystalline NbB2 and Ag. The preparation method is that NbB2 and Ag are used as target materials, and the thin film material is prepared by using a magnetron sputtering method under a mixed atmosphere of methane and argon. The NbB2-C-Ag thin film material prepared by using the above NbB2-C-Ag wide-temperature-range lubricating thin film material and the preparation method thereof has a compact structure, high hardness and toughness, and excellent lubricating performance at room temperature to 800 DEG C, and the traditional boride is widened in a friction lubricating protection system in a wide temperature range.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of protective coating, in particular to a NbB2-C-Ag wide-temperature-range lubricating film material and a preparation method thereof. BACKGROUND

[0002] With the deep exploration of aviation, aerospace and deep earth and the high-speed development of modern industry, various mechanical, transmission and high-precision parts are in complex extreme service environments (high temperature, oxidation, corrosion, radiation and other comprehensive environments) at high temperature. For example, the parts of high thrust-to-weight ratio aerospace engines are in harsh environments such as high temperature, high load and high speed for a long time; and drill bits and cutting tools face high temperature and high pressure environments during work. Under extreme environments, friction and wear of materials are one of the most critical problems affecting the service life of equipment. Traditional lubricating materials are difficult to effectively lubricate in a wide temperature range, such as lubricating oil, which is destroyed and fails at a temperature above 300 DEG C, and MoS2 is oxidized and fails at high temperature. Metal-based materials often do not have enough hardness and cannot provide enough support, and are often accompanied by high wear rate. Therefore, it is imperative to develop new wide-temperature-range (25-800 DEG C) high-wear-resistant self-lubricating materials.

[0003] In the field of wide-temperature-range protective coating, ceramic-based materials are the most potential system in wide-temperature-range solid lubricating materials due to their hardness, lubricity and other comprehensive properties. Borides have high hardness, oxidation resistance and chemical stability due to strong covalent bond network, and are excellent choices for high-temperature lubricating materials. Borides have a relatively low friction coefficient at high temperatures, but a relatively high friction coefficient at room temperature and medium temperature; and the toughness of borides is also low and needs to be improved. Therefore, it is very important to develop a ceramic-based protective lubricating material with self-lubricating function in a wide temperature range. SUMMARY

[0004] The application aims to provide a NbB2-C-Ag wide-temperature-range lubricating film material and a preparation method thereof, so as to solve the problems of low friction coefficient of borides at high temperature, high friction coefficient at room temperature and medium temperature and low toughness.

[0005] To achieve the above-mentioned purpose, the first aspect of the application provides a NbB2-C-Ag wide-temperature-range lubricating film material, which comprises amorphous C and nanocrystalline NbB2 and Ag, wherein the amorphous C wraps the nanocrystalline NbB2 and Ag.

[0006] Preferably, the thickness of the film material is 2 microns.

[0007] The second aspect of the application provides a preparation method of a NbB2-C-Ag wide-temperature-range lubricating film material, which uses NbB2 and Ag as target materials, and prepares the film material by using a magnetron sputtering method in a mixed atmosphere of methane and argon.

[0008] Preferably, the preparation process of the thin film material comprises the following steps:

[0009] (1) Preparation of the substrate

[0010] The substrate is cut and pretreated to obtain a steel base;

[0011] (2) Target placement

[0012] The NbB2 target and the Ag target are placed in the target table, and the steel base and the Si base are placed in the sample table. The film deposition chamber is closed, the gas valve is closed, and vacuum is drawn.

[0013] (3) Target pre-sputtering

[0014] (4) Substrate cleaning

[0015] (5) Film deposition

[0016] The target-substrate distance and the temperature control system are adjusted, the substrate is loaded with a bias voltage, and a mixture of methane and argon gas is introduced. When the deposition thickness is as required, the sputtering is stopped, and the thin film material is removed from the film deposition chamber after natural cooling.

[0017] Preferably, the specific process of step (1) is to select 718 base steel, cut into a 2.5 cm diameter and 5 mm thick original piece using wire cutting, polish to brightness using 400#, 800#, and 1200# sandpaper respectively, and then polish using a polishing machine with alumina powder to obtain a steel base. The Si base and the steel base are ultrasonically cleaned in acetone and ethanol for 20 minutes to remove surface grease and moisture, and dried with nitrogen.

[0018] Preferably, in step (2), a mechanical pump and a molecular pump are used in sequence to draw vacuum to below 8x10 -4 Pa.

[0019] Preferably, the specific process of step (3) is to keep the sample baffle closed and sputter clean the target surface for 20 minutes in an argon atmosphere.

[0020] Preferably, the specific process of step (4) is to open the sample baffle, load a bias voltage of 500-800V on the substrate in an argon atmosphere, and clean the substrate with a sample table glow.

[0021] Preferably, in step (5), the target-substrate distance is 80 mm, the temperature of the sample table is room temperature-800°C, the substrate is loaded with a bias voltage of -40 to -200V, the substrate self-rotation speed is 20R / min, the NbB2 target power is 150W, and the Ag target power is 2-15W.

[0022] Preferably, the specific process of step (5) is to adjust the target base distance to 80 mm, adjust the temperature control system so that the sample table is heated to 400 DEG C and kept, the sample baffle is kept open, the base is loaded with a bias of -40 V, the mixed gas of methane and argon is introduced, the volume ratio of argon and methane is 4:1, the gate valve between the molecular pump and the coating chamber is adjusted, the mixed gas pressure is controlled to 0.6 Pa, the base rotation speed is 20 R / min, the NbB2 target power is 150 W, and the Ag target power is 5 W.

[0023] Therefore, the NbB2-C-Ag wide temperature range lubricating film material and the preparation method thereof have the following beneficial effects:

[0024] (1) The material composition and preparation environment of the present application are optimized, so that the NbB2-C-Ag thin film material structure is dense, high in hardness and good in toughness.

[0025] (2) The thin film material of the present application has different lubrication mechanisms at different temperatures. At room temperature, the lubrication is mainly based on the easy shearing property of Ag and the generated graphite during friction, at 400 DEG C, the lubrication is mainly based on the lubrication of oxides, and at 600-800 DEG C, the lubrication is mainly based on boron oxide and AgNbO3, and the mixed lubrication mechanism comprehensively improves the friction performance of borides in a wide temperature range.

[0026] (3) The NbB2-C-Ag thin film material prepared by the present application reduces the friction coefficient of traditional borides at room temperature and medium temperature (400 DEG C), has excellent lubricating ability at room temperature to 800 DEG C, widens the friction and lubrication protection system of borides in a wide temperature range, and makes the boride-based material suitable for wide temperature range recycling, with long service life.

[0027] The technical solutions of the present application are further described in detail below by means of the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is the XRD diagram of the thin film material prepared in example 1 and NbB2-C and NbB2;

[0029] Figure 2 is the SEM diagram of the thin film material prepared in example 1;

[0030] Figure 3 is the high temperature friction performance diagram of the NbB2-C-Ag thin film material prepared in example 1, the NbB2-C thin film and the NbB2 thin film;

[0031] Figure 4 is the wear scar morphology of the NbB2 thin film, the NbB2-C thin film and the NbB2-C-Ag thin film prepared in example 1 after friction at different temperatures;

[0032] Figure 5 Figure 4 is a Raman spectrum of the product after friction at different temperatures of the NbB2-C-Ag thin film material prepared in Example 1;

[0033] Figure 6 Figure 5 is a surface crack diagram of the product of Example 1 and Comparative Examples 1-2;

[0034] Figure 7 Figure 6 is a TEM diagram of the thin film material prepared in Example 1. DETAILED DESCRIPTION

[0035] The present application will be further described below. It should be noted that the present embodiment is based on the technical solution of the present application, and gives a detailed implementation and specific operation process, but the present application is not limited to the present embodiment.

[0036] Example 1

[0037] A preparation method of a NbB2-C-Ag wide-temperature-range lubricating thin film material, comprising the following steps:

[0038] (1) Preparation of the substrate

[0039] 718 base steel is selected, and a raw piece with a diameter of 2.5 cm and a thickness of 5 mm is cut by wire cutting. The steel substrate, Si substrate and steel substrate are polished to be bright using 400#, 800# and 1200# sandpaper respectively, and then polished using an aluminum oxide powder polishing machine. The steel substrate, Si substrate and steel substrate are ultrasonically cleaned in acetone and ethanol for 20 minutes to remove oil and moisture on the surface, and nitrogen is used to dry at each step.

[0040] (2) Target placement

[0041] The NbB2 target and the Ag target are placed on the target table, and the steel substrate and the Si substrate are placed on the sample table. The film coating chamber is closed, the gas valve is closed, and the mechanical pump and the molecular pump are used to vacuum to less than 8x10 -4 Pa;

[0042] (3) Target pre-sputtering

[0043] Before formal film coating, in order to avoid the influence of impurities such as oxides on the surface of the target, the target surface needs to be pre-sputtered and cleaned. The sample shutter is kept closed, and the target surface is sputtered and cleaned in an argon atmosphere for 20 minutes.

[0044] (4) Substrate cleaning

[0045] The sample shutter is opened, and the substrate is loaded with a bias voltage of 500-800V in an argon atmosphere. The sample table is used to clean the substrate by glow discharge, thereby enhancing the adhesion between the substrate and the thin film.

[0046] (5) Film coating

[0047] Adjust the target distance to 80mm, adjust the temperature control system so that the sample table is heated to 400℃ and kept, the sample shutter is kept open, the substrate is loaded with a bias of -40V, the mixed gas of methane and argon is introduced, the volume ratio of argon and methane is 4:1, the gate valve between the molecular pump and the coating chamber is adjusted, the pressure of the mixed gas is controlled to be 0.6Pa, the substrate rotation speed is 20R / min, the NbB2 target power is 150W, and the Ag target power is 5W.

[0048] (6) End of experiment

[0049] When the deposition thickness reaches 2 microns, when the deposited film thickness is 2μm, the sputtering power is turned off to stop sputtering, the gas inlet is stopped, the coating chamber is kept below 8×10 -4 Pa vacuum degree, and the film is naturally cooled to room temperature and taken out of the coating chamber.

[0050] Example 2

[0051] Example 2 differs from Example 1 in that the Ag target power is 10W.

[0052] Example 3

[0053] Example 3 differs from Example 1 in that the Ag target power is 15W.

[0054] Comparative Example 1

[0055] The difference from Example 1 is that no Ag target is used, and NbB2-C film material is prepared.

[0056] Comparative Example 2

[0057] The difference from Example 1 is that no Ag target is used, and NbB2 film material is prepared.

[0058] Test Example 1

[0059] The NbB2-C-Ag film material prepared in Example 1 is subjected to XRD, SEM and Raman spectrum tests.

[0060] It can be seen from Figure 1 that the film is in a nanocrystalline state, and the NbB2-C-Ag film has been successfully synthesized.

[0061] It can be seen from Figure 2 that the NbB2-C-Ag film is in a nanocrystalline state and forms a dense film. It can be seen from Figure 7 that the film presents a structure of amorphous C wrapping nanocrystalline NbB2 and Ag.

[0062] It can be seen fromFigure 5 It can be seen from the figure that after high temperature friction at different temperatures, the NbB2-C-Ag film prepared in Example 1 appeared Ag2Nb4O 11 , B2O3, Nb2O5 characteristic peaks at 600℃. This is because the oxide Nb2O5 and B2O3 formed by NbB2 at high temperature have low shear strength at high temperature, and NbB2 can be used as a solid lubricant for high temperature lubrication wear-resistant protective coating. However, NbB2 has poor lubrication performance at low temperature, high friction coefficient, and borides also have the characteristics of insufficient toughness, which is easy to crack and fail during protection, so it is difficult to ensure the full-temperature friction reduction and wear-resistant protection function from room temperature to high temperature by relying on the lubricating phase formed by the oxidation of NbB2 material. The layered low shear of graphene and the low shear of Ag can have good lubricity at low temperature, and Ag can also form high-temperature lubricants such as silver niobate AgNbO3 at high temperature. The introduction of C and Ag elements into the boride coating can obtain a self-lubricating coating with low friction and high wear resistance.

[0063] MTS NANO Indentation G200 nanoindentation instrument uses CSM mode, uses a displacement control loading function of 10 nm / s, a Berkovich diamond indenter is used as the indenter, and fused quartz is used for calibration. The indentation depth is 600 nm, and 9 tests are performed on each sample. From the indentation of Figure 6 It can be seen from the figure that NbB2 has some edge cracks, and NbB-C and NbB-C-Ag samples have no cracks, indicating that the toughness of the samples is good.

[0064] The introduction of C in boride can form part of solid solution carbon and part of precipitated carbon, which can improve the toughness of boride and increase the wear resistance, and in-situ form graphite to reduce the friction coefficient at low temperature. Continue to introduce Ag in boride, because Ag itself has low shear, can reduce low temperature friction, and form lubricants such as silver niobate AgNbO3 at higher temperature to reduce the friction coefficient at high temperature.

[0065] Test Example 2

[0066] The high temperature friction performance of the films of Example 1 and Comparative Examples 1-2 was evaluated using a high temperature friction and wear tester. The counter electrode is an alumina ball with a diameter of 6 mm, the load is 1 N, the rotation speed is 40 R / min, the friction radius is 4 mm, the friction linear velocity is 0.42 cm / s, and the experiment is carried out in an atmospheric environment, and the friction temperature is 25-800℃.

[0067] The test results are shown in the following table: Figure 3 From the figure, it can be seen that the friction coefficient of the NbB2-C-Ag film prepared in Example 1 is the lowest among the four samples, and the wear resistance is the best. Figure 3As can be seen from the results, the friction coefficient of the NbB2-C-Ag film prepared in Example 1 is lower than that of the NbB2-C film and the NbB2 film at different temperatures. The NbB2-C-Ag film prepared in this invention has excellent lubrication ability from room temperature to 800°C, which broadens the friction lubrication protection system in a wide temperature range.

[0068] from Figure 4 The results show the wear marks morphology of NbB2 film, NbB2-C film and NbB2-C-Ag film after friction at different temperatures. The NbB2-C-Ag film material prepared in Example 1 shows little surface change after friction at different temperatures and has strong lubrication ability.

[0069] Therefore, this invention provides a NbB2-C-Ag wide-temperature-range lubricating thin film material with the above-mentioned structure and its preparation method. The prepared NbB2-C-Ag thin film material has a dense structure, high hardness and toughness, and excellent lubrication performance from room temperature to 800°C, thus broadening the traditional boride friction lubrication protection system in a wide temperature range.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A NbB2-C-Ag wide temperature range lubricating thin film material, characterized in that: The thin film material comprises amorphous C and nanocrystalline NbB2 and Ag, wherein the amorphous C wraps the nanocrystalline NbB2 and Ag, and is prepared by using NbB2 and Ag as target materials, and using a magnetron sputtering method under a mixed atmosphere of methane and argon, and is suitable for a temperature range of room temperature to 800 DEG C.

2. The NbB2-C-Ag wide temperature range lubricating film material of claim 1, wherein: The thin film material has a thickness of 2 microns.

3. The NbB2-C-Ag wide temperature range lubricating film material of claim 1, wherein: The preparation process of the thin film material specifically comprises the following steps: (1) Preparation of the substrate The substrate is cut and pretreated to obtain a steel substrate; (2) Target material placement The NbB2 target material and the Ag target material are placed in a target table, the steel substrate and the Si substrate are placed in a sample table, the film coating chamber is closed, the gas valve is closed, and vacuum is drawn; (3) Target material pre-sputtering (4) Substrate cleaning (5) Film coating The target-substrate distance and the temperature control system are adjusted, the substrate is loaded with a bias voltage, a mixed gas of methane and argon is introduced, the sputtering is stopped when the required deposition thickness is obtained, and the thin film material is taken out of the film coating chamber after natural cooling.

4. The NbB2-C-Ag wide temperature range lubricating film material of claim 3, wherein: The specific process of step (1) is to select 718 base steel, cut the original piece into a diameter of 2.5 cm and a thickness of 5 mm using a wire cutting, polish it to be bright using 400#, 800# and 1200# sandpaper respectively, and then polish it using an aluminum oxide powder polishing machine to obtain the steel substrate, and the Si substrate and the steel substrate are ultrasonically cleaned in acetone and ethanol for 20 minutes to remove oil and moisture, and dried with nitrogen.

5. The NbB2-C-Ag wide temperature range lubricating film material of claim 3, wherein: In step (2), the mechanical pump and the molecular pump are used in sequence to evacuate to below 8 x 10 -4 Pa.

6. The NbB2-C-Ag wide temperature range lubricating film material of claim 3, wherein: The specific process of step (3) is to keep the sample baffle closed and sputter clean the target surface in an argon atmosphere for 20 minutes.

7. The NbB2-C-Ag wide temperature range lubricating film material of claim 3, wherein: The specific process of step (4) is to open the sample baffle, load a bias voltage of 500-800 V on the substrate in an argon atmosphere, and clean the substrate with a sample table glow.

8. The NbB2-C-Ag wide temperature range lubricating film material of claim 3, wherein: In step (5), the target-substrate distance is 80 mm, the temperature of the sample table is room temperature-800 DEG C, the substrate is loaded with a bias voltage of-40 to-200 V, the substrate self-rotation speed is 20 R / min, the NbB2 target power is 150 W, and the Ag target power is 2-15 W.

9. The NbB2-C-Ag wide temperature range lubricating film material of claim 8, wherein: The specific process of step (5) is to adjust the target-substrate distance to 80 mm, adjust the temperature control system so that the sample table is heated to 400 DEG C and kept, keep the sample baffle open, load a bias voltage of-40 V on the substrate, introduce a mixed gas of methane and argon, the volume ratio of argon to methane is 4:1, adjust the gate valve between the molecular pump and the film coating chamber to control the pressure of the mixed gas to be 0.6 Pa, the substrate self-rotation speed is 20 R / min, the NbB2 target power is 150 W, and the Ag target power is 5 W.

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