A wear-resistant self-lubricating diamond-like carbon-based composite coating and its preparation method and application

Abstract

The present invention discloses a wear-resistant and self-lubricating diamond-like composite coating, a preparation method thereof, and an application thereof. The wear-resistant and self-lubricating diamond-like composite coating of the present invention comprises a Cr layer, a CrN layer, and a functional layer stacked in sequence, the functional layer comprises a plurality of DLC-B4C-WC composite layers and a plurality of DLC-MoS2 composite layers, and the DLC-B4C-WC composite layers and the DLC-MoS2 composite layers are alternately arranged, the layer closest to the CrN layer in the functional layer is the DLC-B4C-WC composite layer, and the layer farthest from the CrN layer is the DLC-MoS2 composite layer. The wear-resistant and self-lubricating diamond-like composite coating of the present invention has the advantages of high hardness, low friction coefficient, self-lubrication, long service life, etc., can be used as a surface protective coating for key components of a drive mechanism to improve the operational reliability and stability of aerospace equipment, and is suitable for large-scale industrial applications.

Description

Technical Field

[0001] The present invention relates to the technical field of surface treatment, and in particular to a wear-resistant, self-lubricating diamond-like carbon-based composite coating, a preparation method thereof, and an application thereof. Background Art

[0002] The drive mechanisms of aerospace equipment are exposed to harsh environments such as high vacuum, strong radiation, atomic oxygen corrosion, and alternating high and low temperatures for extended periods of time. These conditions can easily lead to problems such as seizure, surface scratching, and adhesive wear, which can severely impact the service life of the drive components. Therefore, surface treatment of aerospace equipment components is urgently needed to improve their wear resistance and self-lubrication properties, thereby extending their service life.

[0003] Research has found that by using physical vapor deposition technology (e.g. magnetron sputtering) to deposit a wear-resistant / self-lubricating coating on the surface of the drive mechanism components, the performance and service life of the components can be improved without affecting the size and shape of the components. Diamond-like carbon (DLC) films have the advantages of high hardness, excellent wear resistance, and good chemical stability, and have good application prospects in improving the service life of components of the drive mechanism of aerospace equipment. However, DLC films have disadvantages such as poor thermal stability and poor environmental adaptability. They will gradually undergo graphitization at higher temperatures, resulting in a significant decrease in their hardness and wear resistance. In addition, DLC films will also suffer from severe adhesive wear in a high vacuum environment, resulting in a short service life.

[0004] Therefore, it is of great significance to develop a diamond-like carbon-based coating with high hardness, low friction coefficient, self-lubrication and long service life. Summary of the Invention

[0005] The purpose of the present invention is to provide a wear-resistant, self-lubricating diamond-like carbon-based composite coating, a preparation method thereof and an application thereof.

[0006] The technical solution adopted by the present invention is:

[0007] A wear-resistant, self-lubricating diamond-like carbon (DLC)-based composite coating comprises a Cr layer, a CrN layer, and a functional layer stacked in sequence; the functional layer comprises a plurality of DLC-B4C-WC composite layers and a plurality of DLC-MoS2 composite layers, and the DLC-B4C-WC composite layers and the DLC-MoS2 composite layers are alternately arranged; the layer closest to the CrN layer in the functional layer is the DLC-B4C-WC composite layer, and the layer farthest from the CrN layer is the DLC-MoS2 composite layer.

[0008] Preferably, the thickness of the Cr layer is 0.1 μm to 0.2 μm.

[0009] Preferably, the thickness of the CrN layer is 0.1 μm to 0.2 μm.

[0010] Preferably, the thickness of the functional layer is 1.5 μm to 5 μm.

[0011] Preferably, the thickness of the DLC-B4C-WC composite layer is 0.01 μm to 0.3 μm.

[0012] Preferably, the thickness of the DLC-MoS2 composite layer is 0.01 μm to 0.3 μm.

[0013] A method for preparing the wear-resistant, self-lubricating diamond-like carbon-based composite coating as described above comprises the following steps:

[0014] 1) In a protective atmosphere, Cr is deposited on the surface of the metal substrate by DC magnetron sputtering of a Cr target to form a Cr layer;

[0015] 2) In a nitrogen-containing protective atmosphere, CrN is deposited on the surface of the Cr layer by DC magnetron sputtering of a Cr target to form a CrN layer;

[0016] 3) In a protective atmosphere, DLC, B4C and WC are deposited on the surface of the CrN layer by high-power pulsed magnetron sputtering of graphite target, B4C target and WC target to form a DLC-B4C-WC composite layer;

[0017] 4) In a protective atmosphere, DLC and MoS2 are deposited on the surface of the DLC-B4C-WC composite layer by medium-frequency magnetron sputtering of a graphite target and a MoS2 target to form a DLC-MoS2 composite layer;

[0018] 5) Repeating steps 3) and 4) to alternately deposit DLC-B4C-WC composite layers and DLC-MoS2 composite layers to form a functional layer, thereby obtaining a wear-resistant and self-lubricating diamond-like carbon-based composite coating.

[0019] Preferably, the protective atmosphere in step 1) is an argon atmosphere.

[0020] Preferably, the metal matrix in step 1) is one of a 2Cr13 martensitic stainless steel matrix, a 05Cr17Ni4Cu4Nb martensitic stainless steel matrix, and a YG6 cemented carbide matrix.

[0021] Preferably, the purity of the Cr target in step 1) is higher than 99.95%.

[0022] Preferably, the DC magnetron sputtering in step 1) is carried out under the conditions of a working gas pressure of 0.4 Pa to 1.0 Pa and a Cr target current of 1.0 A to 3.0 A.

[0023] Preferably, the metal substrate in step 1) is pretreated before use, and the pretreatment includes the following steps:

[0024] a) grinding and polishing the surface of the metal substrate (removing the oxide film on the surface);

[0025] b) The metal substrate was ultrasonically cleaned with acetone and anhydrous ethanol for 10 to 20 minutes each (to remove grease and contaminants on the surface and make the surface of the metal substrate smooth), blown dry, and then placed in a protective atmosphere and Ar-ionized on the surface of the substrate using an anode layer ion source. + Etching (removing pollutants and oxide layers on the surface of the metal substrate, thereby improving the bonding strength between the metal substrate and the coating).

[0026] Preferably, in step b) Ar + The etching is performed under the condition of a bias voltage of -1000V to -800V.

[0027] Preferably, the nitrogen-containing protective atmosphere in step 2) is a nitrogen-argon mixed atmosphere.

[0028] Preferably, the purity of the Cr target in step 2) is higher than 99.95%.

[0029] Preferably, the DC magnetron sputtering in step 2) is carried out under the conditions of a working gas pressure of 0.8 Pa to 1.0 Pa and a Cr target current of 1.0 A to 3.0 A.

[0030] Preferably, the protective atmosphere in step 3) is an argon atmosphere.

[0031] Preferably, the purity of the B4C target material in step 3) is higher than 99.5%, and the B content is 85% to 90%.

[0032] Preferably, the purity of the WC target in step 3) is higher than 99.5%, and the W content is 90% to 95%.

[0033] Preferably, the high-power pulsed magnetron sputtering in step 3) is carried out under the conditions of a working gas pressure of 0.5 Pa to 1.0 Pa, an average sputtering power of 2.0 kW to 6.0 kW, and a bias voltage of -350 V to 0 V.

[0034] Preferably, the protective atmosphere in step 4) is an argon atmosphere.

[0035] Preferably, the medium frequency magnetron sputtering in step 4) is carried out under the conditions of a working gas pressure of 0.5 Pa to 1.0 Pa, an average sputtering power of 0.5 kW to 3.0 kW, and a bias voltage of -350 V to 0 V.

[0036] A space equipment comprising the above-mentioned wear-resistant and self-lubricating diamond-like carbon-based composite coating.

[0037] The beneficial effects of the present invention are as follows: the wear-resistant and self-lubricating diamond-like carbon-based composite coating of the present invention has the advantages of high hardness, low friction coefficient, self-lubrication, and long service life. It can be used as a surface protective coating for key components of a drive mechanism to improve the operational reliability and stability of aerospace equipment, and is suitable for large-scale industrial applications.

[0038] Specifically:

[0039] 1) The wear-resistant and self-lubricating diamond-like carbon-based composite coating of the present invention comprises a Cr layer, a CrN layer and a functional layer stacked in sequence, wherein the Cr layer is used to regulate the compatibility of the metal substrate surface, the CrN layer focuses on connecting the upper and lower layers, enhancing the film-substrate bonding force, and buffering and eliminating the residual internal stress between the metal substrate and the coating, thereby improving the impact resistance of the composite coating, so that the functional layer can be effectively bonded to the metal substrate surface, and the functional layer is not easy to break or fall off during friction. The DLC-B4C-WC composite layer in the functional layer is used to give the composite coating high hardness and wear resistance, and the DLC-MoS2 composite layer in the functional layer is used to give the composite coating self-lubricating and low friction properties, ultimately making the composite coating have the advantages of high hardness, low friction coefficient, self-lubrication, long service life, etc., which can well meet the practical application needs of the aerospace field;

[0040] 2) The present invention adopts a gradient multi-layer coating design to overcome the problem of performance mismatch between the coating and the substrate, to maximize the stress relief of the coating itself and between the coatings, to reduce the generation of cracks, and to improve the bonding strength between the coating and the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic structural diagram of the wear-resistant, self-lubricating diamond-like carbon-based composite coating of the present invention.

[0042] Description of the accompanying drawings: 10, metal substrate; 20, Cr layer; 30, CrN layer; 40, functional layer; 401, DLC-B4C-WC composite layer; 402, DLC-MoS2 composite layer.

[0043] Figure 2 This is a relationship curve between the friction coefficient and the number of friction cycles of the wear-resistant self-lubricating diamond-like carbon-based composite coating of Example 1. DETAILED DESCRIPTION

[0044] The present invention will be further explained and illustrated below with reference to specific embodiments.

[0045] Example 1:

[0046] A wear-resistant self-lubricating diamond-like carbon composite coating (schematic diagram as shown Figure 1 As shown), its preparation method is as follows:

[0047] 1) The surface of the 2Cr13 martensitic stainless steel substrate was ground and polished, and then ultrasonically cleaned with acetone and anhydrous ethanol for 15 minutes each, dried, and then placed on the workpiece turntable of the magnetron sputtering coating chamber. The magnetron sputtering coating chamber was evacuated to a pressure below 3×10 -3 Pa, then argon gas was introduced, the negative bias voltage of the workpiece holder was adjusted to -800 V, and the 2Cr13 martensitic stainless steel substrate was cleaned and etched by the anode layer ion source, and the magnetron sputtering coating chamber was evacuated to a pressure below 3×10 -3 Pa, then argon gas was introduced to a pressure of 0.42 Pa, and then a Cr target (purity higher than 99.95%) was magnetron sputtered to deposit Cr on the surface of a 2Cr13 martensitic stainless steel substrate. The distance between the 2Cr13 martensitic stainless steel substrate and the Cr target was 60 cm, and the Cr target current was 3.0 A, forming a Cr layer (thickness of 0.2 μm);

[0048] 2) Maintaining the argon flow rate, nitrogen was introduced at 50 sccm, and the flow rates of argon and nitrogen were adjusted to maintain the working pressure at 0.8 Pa. A Cr target (with a purity greater than 99.95%) was magnetron sputtered to deposit CrN on the surface of the Cr layer. The distance between the 2Cr13 martensitic stainless steel substrate and the Cr target was 60 cm, and the Cr target current was 3.0 A, forming a CrN layer (with a thickness of 0.2 μm).

[0049] 3) maintaining the argon flow rate, stopping the nitrogen flow, maintaining the working pressure at 0.5 Pa, and under the condition that the 2Cr13 martensitic stainless steel substrate is at room temperature (25°C), magnetron sputtering graphite target, B4C target (purity higher than 99.5%, B content of 85%) and WC target (purity higher than 99.5%, W content of 95%) is used to deposit DLC, B4C and WC on the surface of the CrN layer. The average sputtering power is 5.0 kW and the bias voltage is -250 V to form a DLC-B4C-WC composite layer (thickness of 0.3 μm);

[0050] 4) maintaining the argon flow rate and the working pressure at 0.5 Pa, and under the condition that the 2Cr13 martensitic stainless steel substrate is at room temperature (25°C), magnetron sputtering graphite target and MoS2 target are used to deposit DLC and MoS2 on the surface of the DLC-B4C-WC composite layer. The average sputtering power is 3.0 kW and the bias voltage is -250 V, forming a DLC-MoS2 composite layer (with a thickness of 0.3 μm);

[0051] 5) Repeating steps 3) and 4) to alternately deposit DLC-B4C-WC composite layers and DLC-MoS2 composite layers to form a functional layer consisting of eight DLC-B4C-WC composite layers and eight DLC-MoS2 composite layers alternating with each other, turning off the power supply and bias voltage, turning off the gas, and removing the 2Cr13 martensitic stainless steel substrate after cooling to room temperature to obtain a wear-resistant, self-lubricating diamond-like carbon-based composite coating.

[0052] Performance testing:

[0053] 1) The surface hardness of the wear-resistant and self-lubricating diamond-like composite coating of this embodiment was tested using a NANO G200 nanoindentation measuring instrument. The test showed that the surface hardness of the wear-resistant and self-lubricating diamond-like composite coating was as high as 20.6 GPa.

[0054] 2) The tribological performance of the wear-resistant and self-lubricating diamond-like carbon composite coating of this embodiment was tested under vacuum and room temperature using a HVTRB CSM friction tester. The obtained friction coefficient-friction cycle number relationship curve is shown in FIG. Figure 2 shown.

[0055] Depend on Figure 2 It can be seen that the average friction coefficient of the wear-resistant and self-lubricating diamond-like carbon-based composite coating is as low as 0.019 and the average wear rate is as low as 2.52×10 -7 m 3 / N·m, and it has not failed after 12,000 friction cycles. It has excellent self-lubricating effect and long service life.

[0056] Example 2:

[0057] A wear-resistant, self-lubricating diamond-like carbon-based composite coating is prepared in the same manner as in Example 1, except that the average sputtering power in step 3) is adjusted from 5.0 kW to 6.0 kW.

[0058] After testing (testing method is the same as that of Example 1), the surface hardness of the wear-resistant self-lubricating diamond-like carbon composite coating of this embodiment is as high as 18.3GPa, the average friction coefficient is as low as 0.017 under vacuum and room temperature, and the average wear rate is as low as 1.99×10 -7 m 3 / N·m, and the friction cycle times exceed 12,000 times without failure, with excellent self-lubricating effect and long service life.

[0059] Example 3:

[0060] A wear-resistant, self-lubricating diamond-like carbon-based composite coating is prepared in the same manner as in Example 1, except that the bias voltage in step 3) and step 4) is adjusted from -250V to -150V.

[0061] After testing (testing method is the same as that of Example 1), the surface hardness of the wear-resistant self-lubricating diamond-like carbon composite coating of this embodiment is as high as 19.8GPa, the average friction coefficient is as low as 0.019 under vacuum and room temperature, and the average wear rate is as low as 2.35×10 -7 m 3 / N·m, and the friction cycle times exceed 12,000 times without failure, with excellent self-lubricating effect and long service life.

[0062] Example 4:

[0063] A wear-resistant, self-lubricating, diamond-like composite coating is identical to the wear-resistant, self-lubricating, diamond-like composite coating of Example 1, except that the thickness of the DLC-B4C-WC composite layer and the DLC-MoS2 composite layer are adjusted from 0.3 μm to 0.1 μm.

[0064] After testing (testing method is the same as that of Example 1), the surface hardness of the wear-resistant self-lubricating diamond-like carbon composite coating of this embodiment is as high as 18.4GPa, the average friction coefficient is as low as 0.018 under vacuum and room temperature, and the average wear rate is as low as 2.10×10 -7 m 3 / N·m, and the friction cycle times exceed 12,000 times without failure, with excellent self-lubricating effect and long service life.

[0065] The above embodiments are preferred implementations of the present invention, but the implementations of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A wear-resistant and self-lubricating diamond-like carbon-based composite coating, characterized in that: The composition includes a Cr layer, a CrN layer and a functional layer stacked in sequence; the composition of the functional layer includes multiple DLC-B4C-WC composite layers and multiple DLC-MoS2 composite layers, and the DLC-B4C-WC composite layers and the DLC-MoS2 composite layers are arranged alternately; the layer closest to the CrN layer in the functional layer is the DLC-B4C-WC composite layer, and the layer farthest from the CrN layer is the DLC-MoS2 composite layer; the thickness of the Cr layer is 0.1μm~0.2μm; the thickness of the CrN layer is 0.1μm~0.2μm; the thickness of the functional layer is 1.5μm~5μm; the thickness of the DLC-B4C-WC composite layer is 0.01μm~0.3μm; the thickness of the DLC-MoS2 composite layer is 0.01μm~0.3μm.

2. A method for preparing the wear-resistant and self-lubricating diamond-like carbon-based composite coating according to claim 1, characterized in that: The following steps are involved: 1) In a protective atmosphere, Cr is deposited on the surface of the metal substrate by DC magnetron sputtering of a Cr target to form a Cr layer; 2) In a nitrogen-containing protective atmosphere, CrN is deposited on the surface of the Cr layer by DC magnetron sputtering of a Cr target to form a CrN layer; 3) In a protective atmosphere, DLC, B4C and WC are deposited on the surface of the CrN layer by high-power pulsed magnetron sputtering of graphite target, B4C target and WC target to form a DLC-B4C-WC composite layer; 4) In a protective atmosphere, DLC and MoS2 are deposited on the surface of the DLC-B4C-WC composite layer by medium-frequency magnetron sputtering of a graphite target and a MoS2 target to form a DLC-MoS2 composite layer; 5) Repeat steps 3) and 4) to alternately deposit DLC-B4C-WC composite layers and DLC-MoS2 composite layers to form a functional layer, thereby obtaining a wear-resistant and self-lubricating diamond-like carbon-based composite coating.

3. The preparation method according to claim 2, wherein: Step 1) The metal substrate is one of a 2Cr13 martensitic stainless steel substrate, a 05Cr17Ni4Cu4Nb martensitic stainless steel substrate, and a YG6 cemented carbide substrate.

4. The preparation method according to claim 2 or 3, characterized in that: Step 1) The DC magnetron sputtering is performed under the conditions of a working gas pressure of 0.4 Pa to 1.0 Pa and a Cr target current of 1.0 A to 3.0 A.

5. The preparation method according to claim 2 or 3, characterized in that: Step 2) The DC magnetron sputtering is performed under the conditions of a working gas pressure of 0.8 Pa to 1.0 Pa and a Cr target current of 1.0 A to 3.0 A.

6. The preparation method according to claim 2 or 3, characterized in that: Step 3) The high-power pulsed magnetron sputtering is performed under the conditions of a working gas pressure of 0.5 Pa to 1.0 Pa, an average sputtering power of 2.0 kW to 6.0 kW, and a bias voltage of -350 V to 0 V.

7. The preparation method according to claim 2 or 3, characterized in that: Step 4) The medium frequency magnetron sputtering is performed under the conditions of a working gas pressure of 0.5 Pa to 1.0 Pa, an average sputtering power of 0.5 kW to 3.0 kW, and a bias voltage of -350 V to 0 V.

8. A space equipment, characterized in that: A wear-resistant, self-lubricating diamond-like carbon-based composite coating comprising the wear-resistant, self-lubricating diamond-like carbon-based composite coating according to claim 1.

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