A graphene molybdenum disulfide composite lubricating coating for high load conditions and preparation method thereof

Abstract

A graphene molybdenum disulfide composite lubricating coating for high-load working conditions and a preparation method thereof, the preparation method comprising the following steps: depositing a metal catalyst layer on the surface of a wear-resistant substrate; depositing multiple graphene layers on the surface of the metal catalyst layer; performing plasma etching activation treatment on the top graphene layer; in-situ growing a molybdenum disulfide layer on the surface of the activated graphene layer, and cooling with the furnace to obtain a graphene molybdenum disulfide composite lubricating coating. The present invention uses temperature-controlled plasma etching technology to activate the graphene surface, so that nano-scale structural defects and chemical functional groups are introduced into the graphene layer, forming a large number of active sites, which effectively enhance the chemical bonding force between the graphene layer and the molybdenum disulfide layer, thereby improving the bonding strength and interface stability of the composite lubricating coating, showing significant low friction and wear resistance, and greatly improving the load-bearing capacity and use of the coating.

Description

Technical Field

[0001] The invention relates to the technical field of material surface treatment, and in particular to a graphene molybdenum disulfide composite lubricating coating for high-load working conditions and a preparation method thereof. Background Art

[0002] With the rapid development of mechanical equipment in heavy-load extreme environments such as aerospace, deep-sea equipment, and high-speed trains, their key friction pairs (such as bearings, gears, seals, etc.) have posed severe technical challenges to lubricating materials. In existing technologies, these equipment often bear high contact stresses during service, and about 30-50% of energy losses in industrial systems come from friction. This loss is more significant under high-load conditions, which not only causes huge economic losses, but also seriously affects the service life and reliability of equipment. In a high-load working environment, traditional liquid lubricants are easily squeezed out of the lubrication interface due to pressure, resulting in direct contact between the friction pair surfaces and inability to achieve effective lubrication. Therefore, the development of solid lubricating materials suitable for high-load conditions is of great practical significance.

[0003] In the prior art, two-dimensional materials graphene and molybdenum disulfide exhibit unique tribological properties as solid lubricants. Among them, graphene has an atomic-level thin layer structure and an sp2 hybridized carbon atom network, which provides an ideal shear plane and exhibits characteristics such as ultra-high Young's modulus, excellent thermal conductivity and extremely low friction coefficient; molybdenum disulfide has a unique sandwich layered structure (S-Mo-S), and the layers are bonded by weak van der Waals forces, so it has excellent shear properties. Graphene and molybdenum disulfide are combined to form a heterogeneous structure, which can achieve low friction and long-life lubrication effects at the same time. However, the methods for preparing graphene / molybdenum disulfide composite lubricating coatings in the prior art have the following technical problems: First, the traditional mechanical stripping method has the defect of low yield, and the chemical stripping method has the problem of high defect density, which is difficult to meet the needs of industrial applications; second, the interface of the composite lubricating coating prepared by the above method mainly relies on van der Waals force connection, which is easy to fail under high load conditions. Although researchers used surface chemical modification methods to enhance the bonding strength between graphene and molybdenum disulfide, the interface chemical modification effect was not ideal due to the intrinsic low surface energy of the material. Summary of the invention

[0004] Based on this, the purpose of the present invention is to provide a graphene molybdenum disulfide composite lubricating coating for high-load conditions and a preparation method thereof. The composite lubricating coating has excellent bonding strength and interface stability, and can significantly improve the load-bearing capacity and service life of mechanical parts under high-load conditions.

[0005] A method for preparing a graphene molybdenum disulfide composite lubricating coating for high load conditions comprises the following steps:

[0006] Step S11, sending the cleaned and dried wear-resistant substrate into a first chamber, and depositing a metal catalyst layer on the surface of the wear-resistant substrate by electron beam deposition;

[0007] Step S12, sending the wear-resistant substrate containing the metal catalyst layer into the second chamber, and depositing multiple graphene layers on the surface of the metal catalyst layer by chemical vapor deposition;

[0008] Step S13, sending the wear-resistant substrate containing the multi-layer graphene layer into the sputtering chamber, evacuating the chamber, and then performing plasma etching activation treatment on the top graphene layer;

[0009] Among them, the vacuum is drawn to 2×10 -5 ~1×10 -4 Pa, and at the same time adjust the planetary frame on which the wear-resistant substrate is installed to rotate, with a speed of 5~20r / min; use argon, oxygen or nitrogen as the working gas, the working gas pressure is 0.2-1.0Pa, apply a pulse negative bias to the wear-resistant substrate, the voltage range is -30~-400V, the duty cycle is 20%~70%, the etching temperature is 100℃~600℃, and the etching time is 1~10 min;

[0010] Step S14, heating the sputtering chamber to a preset temperature, using pulsed DC magnetron sputtering technology to in-situ grow a molybdenum disulfide layer on the surface of the activated graphene layer, and cooling it with the furnace to obtain a graphene-molybdenum disulfide composite lubricating coating;

[0011] Among them, the preset temperature is 100℃~600℃, the holding time is 10~40 min, and the planetary frame is adjusted to reciprocate at the same time, the reciprocating angle is 40°~60°, and the rotation speed is 3~10r / min; argon is used as the working gas, and the working gas pressure is 0.2~0.5Pa; a molybdenum disulfide target is used as the cathode target, and a pulse current is applied to the molybdenum disulfide target with a current intensity of 0.1~1.0 A, a duty cycle of 10%~50%, and a frequency of 10~50kHZ; a negative bias is applied to the wear-resistant substrate with a voltage range of -600~-1100V, and a deposition time of 10~90 min.

[0012] Preferably, the graphene molybdenum disulfide composite lubricating coating comprises a wear-resistant substrate, a metal catalyst layer, a multi-layer graphene layer and a molybdenum disulfide layer arranged in sequence from bottom to top, wherein the thickness of the metal catalyst layer is 1~15um, the number of graphene layers is 5~20, the thickness of the single-layer graphene layer is 0.3~0.5nm, the particle size of the molybdenum disulfide layer is 1~5 um, and the coating thickness of the molybdenum disulfide layer is 200~1000 nm.

[0013] Preferably, the material of the wear-resistant substrate is stainless steel, cemented carbide, pipeline steel, aluminum alloy or magnesium alloy.

[0014] Preferably, the material of the metal catalyst layer is nickel, copper, iron, or an alloy of nickel, copper and iron.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] First, the graphene surface is activated by temperature-controlled plasma etching technology. The bombardment of high-energy plasma introduces nanoscale structural defects and chemical functional groups into the graphene layer, forming a large number of active sites. These active sites effectively enhance the chemical bonding force between the graphene layer and the molybdenum disulfide layer, thereby improving the bonding strength and interface stability of the composite lubricating coating.

[0017] Second, by using the pulsed DC magnetron sputtering process to precisely control the process parameters, the MoS2 layer is ensured to be uniformly and continuously deposited on the activated graphene surface, achieving high-quality bonding and controllable thickness of the composite lubricating coating. This structural design enables the composite lubricating coating to exhibit excellent wear resistance and low friction properties under high load conditions, greatly improving the load-bearing capacity and service life of the coating, and meeting the application requirements of mechanical parts under high load conditions.

[0018] Third, the preparation method of the present application is efficient and controllable, which improves the stability of the production process and has significant industrial application potential and commercial value. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the structure of the graphene / molybdenum disulfide composite lubricating coating provided by the present invention;

[0020] Figure 2 This is the Raman spectrum of the graphene / molybdenum disulfide composite lubricating coating;

[0021] Figure 3 This is a friction coefficient curve of the graphene / molybdenum disulfide composite lubricating coating under high load;

[0022] Figure 4 This is a dynamic load scratch test diagram of the graphene / molybdenum disulfide composite lubricating coating;

[0023] Figure 5 This is the Raman spectrum of the graphene / molybdenum disulfide composite lubricating coating under the conditions of Comparative Example 1;

[0024] Figure 6 This is a dynamic load scratch test diagram of the graphene / molybdenum disulfide composite lubricating coating under the conditions of Comparative Example 2;

[0025] Figure 7 This is the graphene surface morphology under the conditions of Comparative Example 5;

[0026] Figure 8 This is the surface morphology of molybdenum disulfide under the conditions of Comparative Example 6.

[0027] Description of main component symbols:

[0028] 11-wear-resistant substrate; 12-multi-layer graphene layer; 13-molybdenum disulfide layer.

[0029] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0030] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0031] The following is a detailed description of a graphene / molybdenum disulfide composite lubricating coating for high-load working conditions provided by the present invention and a preparation method thereof.

[0032] The methods for preparing graphene / molybdenum disulfide composite lubricating coatings based on the existing traditional mechanical stripping method and chemical stripping method have the problems of low yield and high defect density, which are difficult to meet the needs of industrial applications; in addition, the interface of the composite lubricating coating prepared by these methods mainly relies on van der Waals force connection, which is easy to fail under high load conditions. Although researchers have tried to enhance the bonding strength between graphene and molybdenum disulfide through surface chemical modification, the interface chemical modification effect is not ideal due to the low surface energy of graphene itself. In order to solve the above technical problems, the inventors creatively used temperature-controlled plasma etching technology to activate the graphene surface, introduced nanoscale defects and chemical functional groups through high-energy argon ion bombardment, formed active sites, and significantly improved the interface binding energy between graphene and molybdenum disulfide. Subsequently, a pulsed DC magnetron sputtering process was used to in situ continuously deposit a molybdenum disulfide coating with controllable thickness on the activated graphene surface. The prepared graphene / molybdenum disulfide composite lubricating coating was connected by covalent bonds, which not only significantly enhanced the bonding strength and interface stability of the coating, but also exhibited excellent durable lubrication effect under high load conditions, thereby effectively overcoming the problems of low yield, high defect density and weak interface bonding in the existing technology.

[0033] The structure and deposition diagram of the graphene / molybdenum disulfide lubricating coating for high load conditions provided by the present invention (such as Figure 1 As shown), it includes a wear-resistant substrate 11, a metal catalyst layer, a multi-layer graphene layer 12 and a molybdenum disulfide layer 13.

[0034] The wear-resistant substrate 11 can be illustratively made of stainless steel, hard alloy, pipeline steel, aluminum alloy or magnesium alloy, and can also be a commonly used mechanical wear-resistant component material. The material of the metal catalyst layer is nickel, copper, iron, or an alloy of nickel, copper and iron.

[0035] The thickness of the metal catalyst layer is 1-15 μm. The number of layers of the multilayer graphene layer 12 can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, and can also be any other value within the range of 5-20 layers, and the thickness of the single-layer graphene layer is 0.3-0.5 nm. The particle size of the molybdenum disulfide layer 13 is 1-5 μm, and the coating thickness of the molybdenum disulfide layer 13 is 200-1000 nm.

[0036] Through temperature-controlled plasma etching activation treatment, argon ions bombard the graphene surface to form active sites such as nano-scale defects and chemical functional groups. The thickness-controllable molybdenum disulfide layer 13 is continuously grown in situ on the activated graphene surface by pulsed DC magnetron sputtering technology to form a graphene / molybdenum disulfide composite lubricating coating with a robust bonding interface.

[0037] The present invention provides a method for preparing a graphene / molybdenum disulfide composite lubricating coating for high-load working conditions, comprising the following steps:

[0038] Step S11, sending the cleaned and dried wear-resistant substrate into a first chamber, and depositing a metal catalyst layer on the surface of the wear-resistant substrate by electron beam deposition;

[0039] Step S12, sending the wear-resistant substrate containing the metal catalyst layer into the second chamber, and depositing multiple graphene layers on the surface of the metal catalyst layer by chemical vapor deposition;

[0040] Step S13, sending the wear-resistant substrate containing the multi-layer graphene layer into the sputtering chamber, evacuating the chamber, and then performing plasma etching activation treatment on the top graphene layer;

[0041] Step S14, heating the sputtering chamber to a preset temperature, using pulsed DC magnetron sputtering technology to in-situ grow a molybdenum disulfide layer on the surface of the activated graphene layer, and cooling it with the furnace to obtain a graphene-molybdenum disulfide composite lubricating coating.

[0042] In step S13, temperature-controlled plasma etching is used, argon, oxygen or nitrogen is used as the working gas, a pulsed negative bias is applied to the substrate, the voltage range is -30~-400V, the duty cycle is 20%~70%, the etching temperature is 100~600℃, and the etching time is 1~10 min. Active sites such as nanoscale defects and chemical functional groups are formed on the graphene surface by bombardment of argon ions, oxygen ions or nitrogen ions, while maintaining the integrity of the graphene sp2 hybrid structure.

[0043] The negative bias voltage may be -30 V, -50 V, -100 V, -150 V, -200 V, -250 V, -300 V, -350 V or -400 V, or any other value within the range of -30 to -400 V.

[0044] It should be noted that if the negative bias voltage is less than -400V, the kinetic energy of the argon ions is too high, resulting in serious damage and excessive etching of the graphene structure, destroying its sp² hybrid network, and thus weakening the mechanical strength of graphene. If it is greater than -30V, the energy of the argon ions is insufficient and cannot effectively induce the formation of nano-scale defects and oxygen-containing functional groups on the graphene surface, resulting in insufficient surface activation, affecting the uniform deposition of molybdenum disulfide and the interface bonding strength.

[0045] The duty cycle may be 20%, 30%, 40%, 50%, 60% or 70%, etc., or any other value within the range of 20% to 70%.

[0046] The etching temperature may be 100° C., 200° C., 300° C., 400° C., 500° C., or 600° C., or any other value within the range of 100 to 600° C.

[0047] It should be noted that if the etching temperature is less than 100°C, the energy transfer efficiency is low when ions bombard the graphene surface, and it is difficult to effectively break the carbon-carbon bonds on the graphene surface, resulting in insufficient generation of nanoscale defects and chemical functional groups. The active site density is too low and it is impossible to provide sufficient binding points for molybdenum disulfide, thereby weakening the interfacial chemical bonding strength. If the etching temperature is greater than 700°C, it will cause excessive thermal activation of the graphene surface, which will not only cause excessive structural defects and destroy the basic sp² hybrid network structure of graphene, but may also cause the oxygen-containing functional groups that have been formed to decompose or transform into other forms, reducing their chemical affinity with molybdenum disulfide, and ultimately leading to uneven interface bonding of the composite lubricating coating and a decrease in the overall mechanical strength.

[0048] The etching time can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min or 20 min, etc., or it can be any other value within the range of 5 to 20 min.

[0049] It should be noted that if the etching time is less than 5 minutes, the interaction time between argon ions and graphene is insufficient, resulting in insufficient generation of surface active sites, and unable to provide sufficient binding sites to achieve uniform deposition of molybdenum disulfide, thereby affecting the interfacial bonding strength of the composite lubricating coating; if it is greater than 20 minutes, the action time of argon ions is too long, causing excessive etching of the graphene surface, destroying its sp2 hybrid structure, forming too many defect sites, weakening the chemical interaction with molybdenum disulfide, and possibly leading to disorder of the coating structure, reducing the overall stability and durability of the composite lubricating coating.

[0050] For reference, in the present invention, before the temperature-controlled plasma etching activation treatment, the wear-resistant substrate is placed in a vacuum chamber, mounted on a planetary frame, and the vacuum is drawn to 2×10 -5 ~1×10 -4 Pa, and at the same time adjust the planetary carrier to rotate at a speed of 5~20r / min.

[0051] The vacuum can be 2×10 -5 Pa, 3×10 -5 Pa, 4×10 -5 Pa, 5×10 -5 Pa, 6×10 -5 Pa, 7×10 -5 Pa, 8×10 -5 Pa, 9×10 -5 Pa or 1×10 -4 Pa, or 2×10 -5 ~1×10 -4 Any other value within the range of Pa.

[0052] The speed of the planetary carrier rotation can be 5r / min, 6r / min, 7r / min, 8r / min, 9r / min, 10r / min, 11r / min, 12r / min, 13r / min, 14r / min, 15r / min, 16r / min, 17r / min, 18r / min, 19r / min or 20r / min, or any other value within the range of 5~20r / min.

[0053] It should be noted that the rotational motion of the planetary carrier enables argon ions to evenly bombard the graphene surface through continuous multi-angle exposure, thereby precisely activating the surface in multiple directions. This multi-angle activation mechanism not only improves the uniformity of the formation of nano-scale defects and oxygen-containing functional groups, but also effectively avoids local over-etching and ensures the integrity of the graphene sp² hybrid structure. The introduction of rotational motion achieves seamless coverage of surface active sites, laying a solid foundation for the subsequent uniform deposition of molybdenum disulfide.

[0054] By setting up a wear-resistant substrate, multilayer graphene and a temperature-controlled plasma etching process, not only the graphene surface is effectively activated and the uniform and continuous deposition of molybdenum disulfide is promoted, but it is also beneficial to improve the interface robustness between graphene and molybdenum disulfide.

[0055] A MoS2 coating with controllable thickness is continuously deposited in situ on the activated graphene surface by pulsed DC magnetron sputtering technology to form a graphene / MoS2 composite lubricating coating with strong chemical interaction.

[0056] Furthermore, it also includes achieving controllable growth of the molybdenum disulfide coating by regulating process parameters such as sputtering current, duty cycle, frequency, working gas pressure, deposition temperature and deposition time, so as to ensure that the interface between graphene and molybdenum disulfide has excellent bonding strength and interface stability.

[0057] In step S14, in the pulsed DC magnetron sputtering process of the present invention, a molybdenum disulfide target is used as a cathode target, argon is used as a working gas, the working gas pressure is 0.2~0.5Pa, a pulse current is applied to the molybdenum disulfide target, the current intensity is 0.1~1.0A, the duty cycle is 10%~50%, the frequency is 10~50kHZ, a negative bias is applied to the substrate, the voltage range is -600~-1100V, and the deposition time is 10~90 min.

[0058] Among them, the working gas pressure can be 0.2Pa, 0.25Pa, 0.3Pa, 0.35Pa, 0.4Pa, 0.45Pa or 0.5Pa, etc., or it can be any other value within the range of 0.2~0.5Pa.

[0059] The pulse current intensity may be 0.1A, 0.2A, 0.3A, 0.4A, 0.5A, 0.6A, 0.7A, 0.8A, 0.9A or 1A, etc., or any other value within the range of 0.1 to 1.0A.

[0060] It should be noted that if the pulse current intensity is less than 0.1A, it is easy to cause insufficient sputtering rate of molybdenum disulfide and fail to form a uniform and orderly coating. If it is greater than 1A, it is easy to cause plasma instability, resulting in microscopic defects and stress concentration in the coating, thereby reducing the overall quality and performance of the composite lubricating coating.

[0061] The duty cycle may be 10%, 20%, 30%, 40% or 50%, etc., or any other value within the range of 10% to 50%.

[0062] The frequency may be 10 kHz, 20 kHz, 30 kHz, 40 kHz or 50 kHz, etc., or any other value within the range of 10 to 50 kHz.

[0063] The negative bias voltage may be -600V, -700V, -800V, -900V, -1000V or -1100V, etc., or any other value within the range of -600~-1100V.

[0064] The deposition time may be 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min or 90 min, etc., or any other value within the range of 10 to 90 min.

[0065] The above-mentioned deposition time directly determines the structural characteristics of graphene and molybdenum disulfide. If the deposition time is less than 10 minutes, not only can the complete molybdenum disulfide crystal structure not be formed, but it is also impossible to composite with graphene to form an ordered layered heterostructure, resulting in a significant decrease in the lubrication performance and durability of the coating; if the deposition time exceeds 90 minutes, it is easy to cause large-area stacking coverage of the molybdenum disulfide coating, hindering its effective interaction with graphene. Under high load conditions, the coating is prone to stratification and shedding, reducing the overall wear resistance.

[0066] For reference, the particle size of the molybdenum disulfide coating in the present invention is 1-5 μm, and the coating thickness is 200-1000 nm.

[0067] The particle size of the molybdenum disulfide coating may be 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, or any other value within the range of 1 to 5 μm.

[0068] The coating thickness may be 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm or 1000 nm, or any other value within the range of 200 to 1000 nm.

[0069] For reference, in the present invention, before pulsed DC magnetron sputtering is performed to deposit the molybdenum disulfide coating, the substrate with activated graphene is heated and the planetary carrier rotation speed is adjusted, the substrate temperature is 100°C~600°C, the insulation time is 10~40 min, and the planetary carrier is adjusted to reciprocate at a reciprocating angle of 40°~60° and a rotation speed of 3~10r / min.

[0070] The substrate temperature may be 100°C, 200°C, 300°C, 400°C, 500°C or 600°C, or any other value within the range of 100°C to 600°C.

[0071] It should be noted that if the substrate temperature is less than 100°C, it is easy to lead to insufficient crystal growth momentum of molybdenum disulfide, affecting the nucleation and growth of its grains, and further affecting the uniformity and density of the coating; if it is greater than 600°C, it is easy to cause thermal oxidation or structural damage of graphene, reducing the overall stability and durability of the composite lubricating coating.

[0072] The insulation time can be 10 min, 15 min, 20 min, 25 min, 30 min, 35 min or 40 min, etc., or any other value within the range of 10 to 40 min.

[0073] The reciprocating angle may be 40°, 50° or 60°, etc., or any other value within the range of 40° to 60°.

[0074] The planet carrier speed may be 3 r / min, 4 r / min, 5 r / min, 6 r / min, 7 r / min, 8 r / min, 9 r / min or 10 r / min, or any other value within the range of 3 to 10 r / min.

[0075] It should be noted that the reciprocating motion of the planet carrier promotes the uniform distribution and tight adhesion of the molybdenum disulfide coating material on the graphene surface through periodic shear stress. The introduction of reciprocating motion not only improves the uniformity of coating coverage, but also reduces microcracks and stress concentration inside the coating through dynamic stress regulation. This mode of motion ensures that the coating can obtain the best density and uniformity during the deposition process, thereby improving the overall stability and durability of the composite lubricating coating.

[0076] As mentioned above, the preparation method of the present invention is simple and efficient, and can prepare a graphene / molybdenum disulfide composite lubricating coating with a robust interface, which has a low friction coefficient and excellent wear resistance under high load conditions.

[0077] The features and performance of the present invention are further described in detail below in conjunction with the embodiments. Example 1

[0078] This embodiment provides a method for preparing a graphene / molybdenum disulfide composite lubricating coating for high load conditions, comprising the following steps:

[0079] (1) Substrate preparation: Use cemented carbide WC-Co as the wear-resistant substrate and perform surface cleaning and drying.

[0080] (2) Multi-layer high-quality graphene deposition: Electron beam deposition is used to deposit a nickel catalyst layer on the surface of cemented carbide, followed by chemical vapor deposition to deposit 5 layers of high-quality graphene on the wear-resistant substrate. Ensure that the number of graphene layers is controlled between 5 and 20 layers, with high quality, low defects and low surface energy characteristics.

[0081] (3) Temperature-controlled plasma etching activation treatment: Place the graphene-covered wear-resistant substrate in a vacuum chamber and draw the vacuum to 5×10⁻ 5 Pa. The planetary frame was adjusted to rotate, and the speed was set to 10 r / min. Argon was used as the working gas, and the working gas pressure was set to 0.5 Pa. A pulsed negative bias was applied to the substrate, with a voltage range of -50 V, a duty cycle of 40%, an etching temperature of 100°C, and an etching time of 5 min.

[0082] (4) Preparation before deposition of molybdenum disulfide coating: heat treat the chamber, set the substrate temperature to 300 °C, keep warm for 20 min, and adjust the planetary carrier to reciprocate, set the reciprocating angle to 50°, and the rotation speed to 5 r / min.

[0083] (5) MoS2 coating deposition: MoS2 coating was grown in situ on the activated top graphene surface using pulsed DC magnetron sputtering technology. The sputtering parameters were set as follows: MoS2 target was the cathode target, argon gas flow rate was introduced, working gas pressure was 0.3 Pa, pulse current was 1 A, duty cycle was 40%, frequency was 35 kHz, negative bias voltage was set to -800 V, and deposition time was 15 min.

[0084] (6) Cooling in the furnace. The particle size of the molybdenum disulfide coating on the graphene surface is 2 μm, and the coating thickness is 300 nm.

[0085] See also Figure 2 The graphene / MoS2 composite lubricating coating prepared above has E 1 2g , A 1g , D, G and 2D peaks, Raman spectra such as Figure 2 The curve shows that there is interaction between graphene and MoS2 coating, and the two exist stably. The friction and wear results under atmospheric and high load conditions show that the average friction coefficient is less than 0.1 (such as Figure 3 In addition, the interfacial bonding strength of the graphene / MoS2 composite lubricating coating is as high as 23.3N (see Figure 4 ). Example 2

[0086] This embodiment provides a method for preparing a graphene / molybdenum disulfide composite lubricating coating for high load conditions, comprising the following steps:

[0087] (1) Substrate preparation: Use stainless steel 316 as the wear-resistant substrate, clean and dry the surface to ensure that the surface is dust-free and oil-free.

[0088] (2) Multi-layer high-quality graphene deposition: Electron beam deposition is used to deposit a nickel catalyst layer on the surface of stainless steel 316, followed by chemical vapor deposition to deposit 10 layers of high-quality graphene on a wear-resistant substrate. The number of graphene layers is controlled between 5 and 20, with high quality, low defects and low surface energy characteristics.

[0089] (3) Temperature-controlled plasma etching activation treatment: Place the graphene-covered wear-resistant substrate in a vacuum chamber and draw the vacuum to 4×10⁻ 5 Pa. The planetary carrier was adjusted to rotate, and the speed was set to 12 r / min. Oxygen was used as the working gas, and the working gas pressure was set to 0.4 Pa. A pulsed negative bias was applied to the wear-resistant substrate, with a voltage range of -200 V, a duty cycle of 50%, an etching temperature of 200°C, and an etching time of 6 min.

[0090] (4) Preparation before deposition of molybdenum disulfide coating: The chamber is heat treated, the substrate temperature is set to 350 °C, the insulation time is 25 min, and the planetary carrier is adjusted to reciprocate at the same time. The reciprocating angle is set to 55° and the rotation speed is 6 r / min.

[0091] (5) MoS2 coating deposition: MoS2 coating was grown in situ on the activated top graphene surface using pulsed DC magnetron sputtering technology. The sputtering parameters were set as follows: MoS2 target was the cathode target, argon gas flow rate was introduced, working gas pressure was 0.3 Pa, pulse current was 0.6 A, duty cycle was 35%, frequency was 25 kHz, negative bias voltage was set to -850 V, and deposition time was 30 min.

[0092] (6) Cooling in the furnace. The particle size of the molybdenum disulfide coating on the graphene surface is 3 μm and the coating thickness is 400 nm.

[0093] The graphene / MoS2 composite lubricating coating prepared above has E 1 2g , A 1g , D, G and 2D peaks, indicating that there is a strong interface interaction between graphene and MoS2 coating, and the two exist stably. The friction and wear results under atmospheric and high load conditions show that the average friction coefficient is 0.0823, which has excellent wear resistance, and the interface bonding strength is as high as 25.1N. Example 3

[0094] This embodiment provides a method for preparing a graphene / molybdenum disulfide composite lubricating coating for high load conditions, comprising the following steps:

[0095] (1) Substrate preparation: Aluminum alloy 6061 is selected as the wear-resistant substrate, and the surface is polished and cleaned to ensure a smooth and clean surface.

[0096] (2) Multi-layer high-quality graphene deposition: Electron beam deposition is used to deposit a nickel catalyst layer on the surface of aluminum alloy 6061, followed by chemical vapor deposition to deposit 12 layers of high-quality graphene on a wear-resistant substrate. The number of graphene layers is controlled between 5 and 20, with high quality, low defects and low surface energy characteristics.

[0097] (3) Temperature-controlled plasma etching activation treatment: Place the graphene-covered wear-resistant substrate in a vacuum chamber and draw the vacuum to 7×10⁻ 5 Pa. The planetary carrier was adjusted to rotate, and the speed was set to 14 r / min. Nitrogen was used as the working gas, and the working gas pressure was set to 0.55 Pa. A pulsed negative bias was applied to the wear-resistant substrate, with a voltage range of -250 V, a duty cycle of 50%, an etching temperature of 300 °C, and an etching time of 7 min.

[0098] (4) Preparation before deposition of molybdenum disulfide coating: The chamber is heat treated, the substrate temperature is set to 400 °C, the insulation time is 30 min, and the planetary carrier is adjusted to reciprocate at the same time. The reciprocating angle is set to 60° and the rotation speed is 8 r / min.

[0099] (5) MoS2 coating deposition: MoS2 coating was grown in situ on the activated top graphene surface using pulsed DC magnetron sputtering technology. The sputtering parameters were set as follows: MoS2 target was the cathode target, argon gas flow rate was introduced, working gas pressure was 0.35 Pa, pulse current was 0.6 A, duty cycle was 35%, frequency was 30 kHz, negative bias voltage was set to -900 V, and deposition time was 40 min.

[0100] (6) Cooling in the furnace. The particle size of the molybdenum disulfide coating on the graphene surface is 4 μm, and the coating thickness is 450 nm.

[0101] The graphene / MoS2 composite lubricating coating prepared above has E 1 2g , A 1g , D, G and 2D peaks, indicating that there is a strong interface interaction between graphene and MoS2 coating, and the two exist stably. The friction and wear results under atmospheric and high load conditions show that the average friction coefficient is 0.0956, which has excellent wear resistance, and the interface bonding strength is as high as 24.5N. Example 4

[0102] This embodiment provides a method for preparing a graphene / molybdenum disulfide composite lubricating coating for high load conditions, comprising the following steps:

[0103] (1) Substrate preparation: Pipeline steel X65 is selected as the wear-resistant substrate, which is mechanically polished and cleaned to ensure that there are no obvious defects and contamination on the surface.

[0104] (2) Multi-layer high-quality graphene deposition: Electron beam deposition is used to deposit a nickel catalyst layer on the surface of pipeline steel X65, followed by chemical vapor deposition to deposit 10 layers of high-quality graphene on the wear-resistant substrate. The number of graphene layers is controlled between 5 and 20, with high quality, low defects and low surface energy characteristics.

[0105] (3) Temperature-controlled plasma etching activation treatment: Place the graphene-covered wear-resistant substrate in a vacuum chamber and draw the vacuum to 8×10⁻ 5 Pa. The planetary carrier was adjusted to rotate, and the speed was set to 16 r / min. Argon was used as the working gas, and the working gas pressure was set to 0.6 Pa. A pulsed negative bias was applied to the wear-resistant substrate, with a voltage range of -300 V, a duty cycle of 55%, an etching temperature of 400 °C, and an etching time of 8 min.

[0106] (4) Preparation before deposition of molybdenum disulfide coating: The chamber is heat treated, the substrate temperature is set to 4500°C, the insulation time is 30 min, and the planetary carrier is adjusted to reciprocate at the same time. The reciprocating angle is set to 60° and the rotation speed is 7 r / min.

[0107] (5) MoS2 coating deposition: MoS2 coating was grown in situ on the activated top graphene surface using pulsed DC magnetron sputtering technology. The sputtering parameters were set as follows: MoS2 target was the cathode target, argon gas flow rate was introduced, working gas pressure was 0.4 Pa, pulse current was 0.5 A, duty cycle was 40%, frequency was 35 kHz, negative bias voltage was set to -1000 V, and deposition time was 50 min.

[0108] (6) Cooling in the furnace. The particle size of the molybdenum disulfide coating on the graphene surface is 5 μm and the coating thickness is 500 nm.

[0109] The graphene / MoS2 composite lubricating coating prepared above has E 1 2g , A 1g , D, G and 2D peaks, indicating that there is a strong interface interaction between graphene and MoS2 coating, and the two exist stably. The friction and wear results under atmospheric and high load conditions show that the average friction coefficient is 0.0798, which has excellent wear resistance, and the interface bonding strength is as high as 23.9N. Example 5

[0110] This embodiment provides a method for preparing a graphene / molybdenum disulfide composite lubricating coating for high load conditions, comprising the following steps:

[0111] (1) Substrate preparation: Use stainless steel 304L as the wear-resistant substrate, clean and dry the surface to ensure that the surface is dust-free and oil-free.

[0112] (2) Multi-layer high-quality graphene deposition: A nickel catalytic layer is deposited on the surface of stainless steel 304L by electron beam deposition, and then 7 layers of high-quality graphene are deposited on the wear-resistant substrate by chemical vapor deposition.

[0113] (3) Temperature-controlled plasma etching activation treatment: Place the graphene-covered wear-resistant substrate in a vacuum chamber and draw the vacuum to 9×10⁻ 5 Pa. The planetary carrier was adjusted to rotate, and the speed was set to 10 r / min. Nitrogen was used as the working gas, and the working pressure was set to 0.7 Pa. A pulsed negative bias was applied to the wear-resistant substrate, with a voltage range of -350 V, a duty cycle of 45%, an etching temperature of 500 °C, and an etching time of 9 min.

[0114] (4) Preparation before deposition of molybdenum disulfide coating: The chamber is heat treated, the substrate temperature is set to 450 °C, the insulation time is 30 min, and the planetary carrier is adjusted to reciprocate at the same time. The reciprocating angle is set to 60° and the rotation speed is 8 r / min.

[0115] (5) MoS2 coating deposition: MoS2 coating was grown in situ on the activated top graphene surface using pulsed DC magnetron sputtering technology. The sputtering parameters were set as follows: MoS2 target was the cathode target, argon gas flow rate was introduced, working gas pressure was 0.45 Pa, pulse current was 0.7 A, duty cycle was 45%, frequency was 40 kHz, negative bias voltage was set to -1050 V, and deposition time was 60 min.

[0116] (6) Cooling in the furnace. The particle size of the molybdenum disulfide coating on the graphene surface is 4.5 μm and the coating thickness is 700 nm.

[0117] The graphene / MoS2 composite lubricating coating prepared above has E 1 2g , A 1g , D, G and 2D peaks, indicating that there is a strong interface interaction between graphene and MoS2 coating, and the two exist stably. The friction and wear results under atmospheric and high load conditions show that the average friction coefficient is 0.0895, which has excellent wear resistance, and the interface bonding strength is as high as 25.7N. Example 6

[0118] This embodiment provides a method for preparing a graphene / molybdenum disulfide composite lubricating coating for high load conditions, comprising the following steps:

[0119] (1) Substrate preparation: Magnesium alloy is selected as the wear-resistant substrate, and then mechanical grinding and cleaning are performed to ensure that there are no obvious defects and pollution on the surface.

[0120] (2) Multi-layer high-quality graphene deposition: A nickel catalytic layer is deposited on the surface of stainless steel 304L by electron beam deposition, and then 20 layers of high-quality graphene are deposited on the wear-resistant substrate by chemical vapor deposition.

[0121] (3) Temperature-controlled plasma etching activation treatment: The graphene-covered wear-resistant substrate is placed in a vacuum chamber and the vacuum is drawn to 1×10 ⁻4 Pa. The planetary carrier was adjusted to rotate, and the speed was set to 20 r / min. Argon gas was used as the working gas, and the working gas pressure was set to 1 Pa. A pulsed negative bias was applied to the wear-resistant substrate, with a voltage range of -400 V, a duty cycle of 70%, an etching temperature of 600 °C, and an etching time of 10 min.

[0122] (4) Preparation before deposition of molybdenum disulfide coating: The chamber is heat treated, the substrate temperature is set to 600 °C, the insulation time is 40 min, and the planetary carrier is adjusted to reciprocate at the same time. The reciprocating angle is set to 60° and the rotation speed is 10 r / min.

[0123] (5) MoS2 coating deposition: MoS2 coating was grown in situ on the activated top graphene surface using pulsed DC magnetron sputtering technology. The sputtering parameters were set as follows: MoS2 target was the cathode target, argon gas flow rate was introduced, working gas pressure was 0.5 Pa, pulse current was 0.8 A, duty cycle was 50%, frequency was 50 kHz, negative bias voltage was set to -1100 V, and deposition time was 90 min.

[0124] (6) Cooling in the furnace. The particle size of the molybdenum disulfide coating on the graphene surface is 5 μm, and the coating thickness is 1000 nm.

[0125] The graphene / MoS2 composite lubricating coating prepared above has E 1 2g , A 1g , D, G and 2D peaks, indicating that there is a strong interface interaction between graphene and MoS2 coating, and the two exist stably. The friction and wear results under atmospheric and high load conditions show that the average friction coefficient is 0.0904, which has excellent wear resistance, and the interface bonding strength is as high as 26.1N. Example 7

[0126] This embodiment provides a method for preparing a graphene / molybdenum disulfide composite lubricating coating for high load conditions, comprising the following steps:

[0127] (1) Substrate preparation: Stainless steel 904L is selected as the wear-resistant substrate, which is then mechanically polished and cleaned to ensure that there are no obvious defects and contamination on the surface.

[0128] (2) Multi-layer high-quality graphene deposition: A nickel catalytic layer is deposited on the surface of stainless steel 904L by electron beam deposition, and then 18 layers of high-quality graphene are deposited on the wear-resistant substrate by chemical vapor deposition (CVD).

[0129] (3) Temperature-controlled plasma etching activation treatment: The graphene-covered wear-resistant substrate is placed in a vacuum chamber and the vacuum is drawn to 1×10 ⁻4 Pa. The planetary carrier was adjusted to rotate, and the speed was set to 20 r / min. Argon was used as the working gas, and the working gas pressure was set to 0.2 Pa. A pulsed negative bias was applied to the wear-resistant substrate, with a voltage range of -30 V, a duty cycle of 20%, an etching temperature of 450°C, and an etching time of 1 min.

[0130] (4) Preparation before deposition of molybdenum disulfide coating: The chamber is heat treated, the substrate temperature is set to 100 °C, the insulation time is 10 min, and the planetary carrier is adjusted to reciprocate at the same time. The reciprocating angle is set to 40° and the rotation speed is 3 r / min.

[0131] (5) MoS2 coating deposition: MoS2 coating was grown in situ on the activated top graphene surface using pulsed DC magnetron sputtering technology. The sputtering parameters were set as follows: MoS2 target was the cathode target, argon gas flow rate was introduced, working gas pressure was 0.2 Pa, pulse current was 0.1 A, duty cycle was 10%, frequency was 10 kHz, negative bias voltage was set to -600 V, and deposition time was 10 min.

[0132] (6) Cooling in the furnace. The particle size of the molybdenum disulfide coating on the graphene surface is 1 μm and the coating thickness is 200 nm.

[0133] The graphene / MoS2 composite lubricating coating prepared above has E 1 2g , A 1g , D, G and 2D peaks, indicating that there is a strong interface interaction between graphene and MoS2 coating, and the two exist stably. The friction and wear results under atmospheric and high load conditions show that the average friction coefficient is 0.0873, which has excellent wear resistance, and the interface bonding strength is as high as 22.3N. Comparative Example 1

[0134] The preparation method provided in this comparative example is different from that in Example 1 only in that step (3) is missing.

[0135] The Raman spectrum of the graphene / molybdenum disulfide composite lubricating coating obtained in this comparative example (see Figure 5 ) Lack of obvious E 1 2g and A 1g Peaks are shown, only D, G and 2D peaks are shown, indicating that there is a lack of good interaction between the MoS2 coating and graphene. In the friction and wear test under atmospheric and high load conditions, the average friction coefficient increased to 0.357, and the wear resistance decreased significantly. The interface bonding strength decreased to 4.5 N, and the coating was easy to peel off. Comparative Example 2

[0136] The preparation method provided in this comparative example is different from that in Example 1 only in that the pulse current in step (5) is increased to 2A, and the duty cycle is increased to 60%. Under high pulse current and high duty cycle, the energy introduced into the coating increases, which may lead to higher internal stress. High internal stress can easily lead to microcracks in the coating (see Figure 6 ), warping or falling off, reducing the overall density and mechanical integrity of the coating, and making it impossible to continuously grow the MoS2 coating. Excessive energy input may lead to excessive ionization and aggregation of MoS2 particles, forming larger particles or agglomerations. These structural defects will form pores or voids in the coating, further weakening the interfacial interaction between the MoS2 layer and the graphene layer. In friction and wear tests under atmospheric and high load conditions, the average friction coefficient rose to 0.212, and the wear resistance decreased significantly. The interfacial bonding strength dropped to 17.2 N (see Figure 6 ), the coating is easy to peel off. Comparative Example 3

[0137] The preparation method provided in this comparative example is different from that in Example 1 only in that the deposition temperature in step (4) is reduced to 80°C. Low temperature deposition is not sufficient to make MoS 2 The coating structure was loose and poorly dense due to the insufficient crystallization, which was not enough to promote good interaction between MoS2 and graphene layer, resulting in insufficient interface bonding force. The composite lubricating coating fell off, and no subsequent friction and wear detection was performed. Comparative Example 4

[0138] The preparation method provided in this comparative example is different from that in Example 1 only in that the deposition time of molybdenum disulfide in step (5) is increased to 120 min, resulting in a significant increase in the thickness of the molybdenum disulfide coating, resulting in the accumulation of stress inside the coating, increasing the risk of microcracks and warping, reducing the mechanical stability of the coating, and making it easy to peel off and break during wear, significantly reducing the wear resistance. The D peak and D+D' characteristic peaks in the Raman spectrum of the graphene / molybdenum disulfide composite lubricating coating obtained in this comparative example increased significantly, indicating an increase in structural defects. In the friction and wear test under atmospheric and high load conditions, the average friction coefficient increased to 0.37, and the wear resistance decreased significantly. The interface bonding strength decreased to 7.2 N, and the coating was easy to peel off. Comparative Example 5

[0139] The preparation method provided in this comparative example is different from that in Example 1 only in that the etching time in step (3) is increased to 15 min. The increase in etching time causes excessive plasma etching of the graphene surface, resulting in partial damage or complete peeling of the graphene layer. The increase in microcracks and holes in the graphene layer reduces the integrity and continuity of the graphene (see Figure 7 ). In the friction and wear test under atmospheric and high load conditions, the average friction coefficient increased to 0.4315. Excessive etching destroyed the interface balance between graphene and molybdenum disulfide coating, resulting in a weakening of the bonding force between the two, and the interface bonding strength dropped to 5.3N. Comparative Example 6

[0140] The preparation method provided in this comparative example is different from that in Example 1 only in that the etching temperature in step (3) is reduced to 50°C. The reduction in etching temperature leads to insufficient activation of the graphene surface, too low density of nano-scale defects and chemical functional groups, and insufficient chemical binding sites for molybdenum disulfide. After the coating is prepared, it is found that molybdenum disulfide is unevenly distributed on the graphene surface (see Figure 8 ), local peeling is prone to occur under high load conditions. Tribological tests show that the friction coefficient increased significantly to 0.4521, and the interface bonding strength decreased to 3N, which is far from meeting the application requirements of high load conditions.

[0141] The data results of the above embodiments and comparative examples are summarized in Table 1:

[0142] Table 1 Friction coefficient and bonding strength data results

[0143]

[0144] In summary, the graphene / molybdenum disulfide composite lubricating coating for high-load working conditions provided by the present invention and its preparation method, which activates the graphene surface by temperature-controlled plasma etching technology, uses high-energy argon ions to impact the graphene layer, and successfully introduces nano-scale structural defects and chemical functional groups, thereby forming a large number of active sites. These active sites significantly enhance the chemical bonding force between graphene and the molybdenum disulfide coating, and greatly improve the bonding strength and interface stability of the composite lubricating coating. Subsequently, a pulsed DC magnetron sputtering process is used to accurately control the process parameters to ensure that the thickness-controlled molybdenum disulfide coating can be uniformly and continuously deposited on the activated graphene surface, achieving high-quality coating bonding. This structural design enables the composite lubricating coating to exhibit good wear resistance and low friction characteristics under high-load conditions, significantly extending the service life of mechanical parts. In addition, the preparation method of the graphene / molybdenum disulfide coating is efficient and controllable, improves the stability of the industrial production process, and shows broad potential in the application of mechanical wear-resistant devices.

[0145] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a graphene molybdenum disulfide composite lubricating coating for high load conditions, characterized in that: It consists of the following steps: Step S11, sending the cleaned and dried wear-resistant substrate into a first chamber, and depositing a metal catalyst layer on the surface of the wear-resistant substrate by electron beam deposition; Step S12, sending the wear-resistant substrate containing the metal catalyst layer into the second chamber, and depositing multiple graphene layers on the surface of the metal catalyst layer by chemical vapor deposition; Step S13, sending the wear-resistant substrate containing the multi-layer graphene layer into the sputtering chamber, evacuating the chamber, and then performing plasma etching activation treatment on the top graphene layer; Among them, the vacuum is drawn to 2×10 -5 ~1×10 -4 Pa, and at the same time adjust the planetary frame on which the wear-resistant substrate is installed to rotate, with a speed of 5~20r / min; use argon, oxygen or nitrogen as the working gas, the working gas pressure is 0.2-1.0Pa, apply a pulse negative bias to the wear-resistant substrate, the voltage range is -30~-400V, the duty cycle is 20%~70%, the etching temperature is 100℃~600℃, and the etching time is 1~10 min; Step S14, heating the sputtering chamber to a preset temperature, using pulsed DC magnetron sputtering technology to in-situ grow a molybdenum disulfide layer on the surface of the activated graphene layer, and cooling it with the furnace to obtain a graphene-molybdenum disulfide composite lubricating coating; Among them, the preset temperature is 100℃~600℃, the holding time is 10~40 min, and the planetary frame is adjusted to reciprocate at the same time, the reciprocating angle is 40°~60°, and the rotation speed is 3~10r / min; argon is used as the working gas, and the working gas pressure is 0.2~0.5Pa; a molybdenum disulfide target is used as the cathode target, and a pulse current is applied to the molybdenum disulfide target with a current intensity of 0.1~1.0 A, a duty cycle of 10%~50%, and a frequency of 10~50kHZ; a negative bias is applied to the wear-resistant substrate with a voltage range of -600~-1100V, and a deposition time of 10~90 min.

2. The method for preparing the graphene molybdenum disulfide composite lubricating coating for high load conditions according to claim 1, characterized in that: The graphene molybdenum disulfide composite lubricating coating includes a wear-resistant substrate, a metal catalyst layer, a multi-layer graphene layer and a molybdenum disulfide layer arranged in sequence from bottom to top, wherein the thickness of the metal catalyst layer is 1~15um, the number of graphene layers is 5~20, the thickness of the single-layer graphene layer is 0.3~0.5nm, the particle size of the molybdenum disulfide layer is 1~5 um, and the coating thickness of the molybdenum disulfide layer is 200~1000 nm.

3. The method for preparing the graphene molybdenum disulfide composite lubricating coating for high load conditions according to claim 2, characterized in that: The material of the wear-resistant substrate is stainless steel, hard alloy, pipeline steel, aluminum alloy or magnesium alloy.

4. The method for preparing the graphene molybdenum disulfide composite lubricating coating for high load conditions according to claim 2, characterized in that: The material of the metal catalyst layer is nickel, copper, iron, or an alloy of nickel, copper and iron.

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