GCr15 bearing steel surface graphite-like reinforced coating and preparation method thereof

Abstract

The invention relates to the technical field of wear-resistant coatings, in particular to a graphite-like reinforced coating on the surface of GCr15 bearing steel and a preparation method of the graphite-like reinforced coating. The reinforced coating comprises a bonding layer and a wear-resistant lubricating layer, and is obtained by sequentially depositing a Ti bonding layer and the wear-resistant lubricating layer which is formed by co-sputtering a Ti target and a composite target through magnetron sputtering, molybdenum disulfide-graphene core-shell powder, a molybdenum source and a sulfur source are subjected to a hydrothermal reaction to form composite powder with a porous structure on the surface, and the composite powder and carbon powder are mixed and subjected to spray granulation, cold isostatic pressing and sinter molding to obtain the composite target material. By constructing the composite powder of the sandwich structure, controllable release of the lubricating phase is achieved, the coating has high hardness, strong binding force, excellent fracture toughness and ultralow friction coefficient, the problems that hardness and toughness of a traditional coating are difficult to consider, the lubricating phase is easy to exhaust and the like are solved, and the coating is suitable for surface strengthening of high-end bearings.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wear-resistant coating, in particular to a graphite-like reinforced coating on the surface of GCr15 bearing steel and a preparation method thereof. BACKGROUND

[0002] Bearing steel is the core component of mechanical transmission system, and its surface performance directly affects the service life and reliability of equipment. Under harsh working conditions such as high speed and heavy load, the surface of traditional bearing steel is prone to wear, fatigue spalling and other problems. The existing surface modification technologies mainly include chemical heat treatment, physical vapor deposition coating, etc. For example, patent technology document CN119506773A discloses a kind of oil-free bearing surface wear-resistant self-lubricating hydrogen-free carbon-based coating and its preparation method, which includes a binding force layer, a wear-resistant self-lubricating coating and a surface C layer, reduces the friction between the various parts of the oil-free bearing, prolongs the service life of the oil-free bearing; improve the bonding strength between the surface C layer and the wear-resistant self-lubricating coating, and improve the service life of the coating.

[0003] However, a single component of physical vapor deposition coating (such as diamond-like carbon film) has high hardness, but is brittle and has insufficient bonding strength with the substrate; while the traditional MoS2 solid lubricating coating has excellent friction reduction performance, but has poor load capacity and insufficient environmental stability.

[0004] Therefore, the present application constructs a composite coating to improve the poor wettability of the traditional coating and the metal substrate, which leads to insufficient coating bonding strength and uneven distribution of the coating lubricating phase, which easily causes rapid decay of the lubrication and wear resistance. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a graphite-like reinforced coating on the surface of GCr15 bearing steel and a preparation method thereof, which has high hardness, strong bonding force, excellent fracture toughness and ultra-low friction coefficient.

[0006] To achieve the above purpose, the present application provides a graphite-like reinforced coating on the surface of GCr15 bearing steel, which comprises a bonding layer and a wear-resistant lubricating layer, and the bonding layer and the wear-resistant lubricating layer are sequentially deposited on the surface of the bearing steel from the inside to the outside by magnetic control sputtering.

[0007] The present application also provides a preparation method of the graphite-like reinforced coating on the surface of GCr15 bearing steel, which comprises the following steps: S11 substrate pre-cleaning: cleaning the substrate to obtain a pretreated substrate; S12 depositing the bonding layer: placing the pretreated substrate on the sample table of a four-target closed-field unbalanced magnetic control sputtering device, the sputtering target material is Ti metal target material or Cr metal target material, and the deposition time is 10-20 min; S13: Depositing a wear-resistant lubricating layer: the sputtering target material is a Ti metal target and a composite target, and the deposition time is 10-30 min; The preparation step of the composite target in step S13 is as follows: S21: Mix molybdenum disulfide nanoparticles, polycyclic aromatic hydrocarbon PAH and deionized water, stir for 1-2 h, then add graphene oxide, continue stirring until evenly mixed, and then transfer to a stainless steel autoclave lined with Teflon, keep at 170-180℃ for 20-22 h, to obtain molybdenum disulfide-graphene core-shell powder; S22: Weigh ammonium molybdate, thiourea, carbon nanotubes and molybdenum disulfide-graphene core-shell powder into deionized water, stir evenly, then place in a hydrothermal reaction kettle, react at 150-160℃ for 4-6 h, after the reaction is completed, wash with water, centrifuge, dry and calcine to obtain a composite powder; S23: Mix carbon powder, composite powder and anhydrous ethanol uniformly, ball mill for 8-12 h to obtain a mixed slurry, and then perform spray granulation, cold isostatic pressing, heat treatment sintering and machining in sequence to obtain a composite target.

[0008] Preferably, the cleaning in step S11 is ultrasonic cleaning by placing the substrate in anhydrous ethanol.

[0009] Preferably, the process parameters for depositing the bonding layer in step S12 are as follows: set argon flow rate to 80-100 sccm, working gas pressure to 0.8-1.0 Pa, high-power pulsed magnetron sputtering target voltage pulse width to 1-4 μs, average power to 5-8 kW and negative bias power to -30~-100 V.

[0010] Preferably, the process parameters for depositing the wear-resistant lubricating layer in step S13 are as follows: argon flow rate 80-100 sccm, nitrogen flow rate 20-60 sccm, working gas pressure 0.8-1.0 Pa, high-power pulsed magnetron sputtering target voltage pulse width 1-4 μs, average power 5-8 kW and negative bias power -30~-100 V.

[0011] Preferably, the amount ratio of molybdenum disulfide nanoparticles, polycyclic aromatic hydrocarbon PAH, deionized water and graphene oxide in step S21 is 1-2 g:1-2 g:500-800 mL:0.2-0.4 g.

[0012] Preferably, the particle size of the molybdenum disulfide nanoparticles in step S21 is 50-100 nm.

[0013] Preferably, the flake size of the graphene oxide in step S21 is 1-5 μm.

[0014] Preferably, the amount ratio of the ammonium molybdate, the thiourea, the carbon nanotube, the molybdenum disulfide-graphene core-shell powder and the deionized water in step S22 is 1g:1-2g:0.5g:1-2g:30mL.

[0015] Preferably, the outer diameter of the carbon nanotube in step S22 is 10-20nm, and the length is 0.5-2um.

[0016] Preferably, the calcination temperature in step S22 is 800℃, and the calcination time is 4-6h.

[0017] Preferably, the amount ratio of the carbon powder, the composite powder and the anhydrous ethanol in step S23 is 95-99g:1-5g:20-30mL.

[0018] Preferably, the parameters of the spray granulation in step S23 are that the rotation speed of the atomization disc is 8000-12000rpm, the inlet temperature is 180-240℃, and the outlet temperature is 80-105℃.

[0019] Preferably, the parameters of the cold isostatic pressing in step S23 are 300-400MPa and the pressure maintaining time is 10-20min.

[0020] Preferably, the parameters of the sintering in step S23 are 20-50MPa, 900-1200℃, and the heat preservation time is 3-6h.

[0021] Advantages of the present application: The present application solves the problem of mutual restriction between hardness and toughness by the multi-scale synergistic design, so that the coating has excellent load capacity and friction adaptability. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below with specific examples.

[0023] The sources or properties of the raw materials used in the examples and comparative examples are as follows: molybdenum disulfide nanoparticles: 50-100nm; graphene oxide: 1-5um; carbon nanotube: outer diameter 10-20nm, length 0.5-2um.

[0024] Example 1: a GCr15 bearing steel surface graphite-like reinforced coating, the specific preparation steps are as follows: (1) 1 g of molybdenum disulfide nanoparticles, 1 g of polycyclic aromatic hydrocarbon PAH and 500 mL of deionized water were mixed, stirred for 1 h, and then 0.2 g of graphene oxide was added. After stirring until uniform, it was transferred to a stainless steel autoclave lined with Teflon and kept at 170°C for 20 h to obtain molybdenum disulfide-graphene core-shell powder; (2) 1 g of ammonium molybdate, 1 g of thiourea, 0.5 g of carbon nanotubes and 1 g of molybdenum disulfide-graphene core-shell powder were weighed into 30 mL of deionized water, stirred uniformly and placed in a hydrothermal reactor. React at 150°C for 4 h. After the reaction was completed, it was washed with water, centrifuged, dried, and calcined at 800°C for 4 h to obtain a composite powder; (3) 95 g of carbon powder, 5 g of composite powder and 20 mL of anhydrous ethanol were uniformly mixed and ball milled at 200 rpm for 8 h to obtain a mixed slurry. Then the mixed slurry was spray granulated (import temperature 180°C, export temperature 80°C) and transferred to a cold isostatic pressing mold. Keep pressure at 300 Pa for 10 min to obtain a green body. The green body was placed in a sintering furnace at 20 MPa and 900°C for 3 h. After cooling to room temperature, it was machined to obtain a composite target material; (4) Take GCr15 bearing steel, ultrasonic clean in anhydrous alcohol for 30 min, dry, and obtain pretreated GCr15 bearing steel. Place it on the sample table of a four-target closed field unbalanced magnetron sputtering device. Vacuumize to below 1×10 Pa after closing the door. Set argon flow rate to 80 sccm, working gas pressure to 0.8 Pa, high-power pulsed magnetron sputtering power source target voltage pulse width to 1 μs, average power to 5 kW, and negative bias power source to -30 V. Sputter Ti metal target material for 10 min. After deposition is completed, set argon flow rate to 80 sccm, nitrogen flow rate to 20 sccm, working gas pressure to 0.8 Pa, high-power pulsed magnetron sputtering power source target voltage pulse width to 1 μs, average power to 5 kW, and negative bias power source to -30 V. Sputter Ti metal target material and composite target material for 10 min. Cool to obtain a GCr15 bearing steel surface graphite-like reinforced coating.

[0025] Example 2: A GCr15 bearing steel surface graphite-like reinforced coating, the specific preparation steps are as follows: (1) 1.5 g of molybdenum disulfide nanoparticles, 1.5 g of polycyclic aromatic hydrocarbon PAH and 700 mL of deionized water were mixed, stirred for 2 h, and then 0.3 g of graphene oxide was added. After stirring until uniform, it was transferred to a stainless steel autoclave lined with Teflon and kept at 175°C for 21 h to obtain molybdenum disulfide-graphene core-shell powder; (2) 1 g of ammonium molybdate, 1.5 g of thiourea, 0.5 g of carbon nanotubes and 1.5 g of molybdenum disulfide-graphene core-shell powder were weighed into 30 mL of deionized water, stirred uniformly and then placed in a hydrothermal reaction kettle, reacted at 155°C for 5 h, after the reaction was completed, washed with water, centrifuged, dried, and calcined at 800°C for 5 h to obtain a composite powder; (3) 98 g of carbon powder, 2 g of the composite powder and 25 mL of anhydrous ethanol were uniformly mixed, ball milled at 300 rpm for 10 h to obtain a mixed slurry, then the mixed slurry was spray granulated (import temperature 210°C, export temperature 100°C) and then transferred to a cold isostatic pressing mold, and pressure was maintained at 350 MPa for 15 min to obtain a green body, the green body was placed in a sintering furnace, and pressure was maintained at 35 MPa at 1100°C for 5 h, and after cooling to room temperature, machining was performed to obtain a composite target material; (4) The GCr15 bearing steel was placed in anhydrous alcohol and ultrasonically cleaned for 45 min, dried to obtain pretreated GCr15 bearing steel, and placed on a sample table of a four-target closed field unbalanced magnetron sputtering device, vacuumed to below 1×10 Pa after closing the door, argon flow rate was set to 90 sccm, working gas pressure was set to 0.9 Pa, high-power pulsed magnetron sputtering power supply target voltage pulse width was set to 3 μs, average power was set to 7 kW, and negative bias power supply was set to -70 V, Ti metal target material was sputtered, and deposition time was 15 min; after deposition was completed, argon flow rate was set to 90 sccm, nitrogen flow rate was set to 40 sccm, working gas pressure was set to 0.9 Pa, high-power pulsed magnetron sputtering power supply target voltage pulse width was set to 3 μs, average power was set to 7 kW, and negative bias power supply was set to -70 V, Ti metal target material and the composite target material were sputtered, and deposition time was 30 min, and cooling was performed to obtain a GCr15 bearing steel surface graphite-like reinforced coating.

[0026] Example 3: A GCr15 bearing steel surface graphite-like reinforced coating, and the specific preparation steps are as follows: (1) 2 g of molybdenum disulfide nanoparticles, 2 g of polycyclic aromatic hydrocarbon PAH and 800 mL of deionized water were mixed, stirred for 2 h, 0.4 g of graphene oxide was added, and stirring was continued until uniform, then transferred to a stainless steel autoclave lined with Teflon, and kept at 180°C for 22 h to obtain molybdenum disulfide-graphene core-shell powder; (2) 1 g of ammonium molybdate, 2 g of thiourea, 0.5 g of carbon nanotubes and 2 g of molybdenum disulfide-graphene core-shell powder were weighed into 30 mL of deionized water, stirred uniformly and then placed in a hydrothermal reaction kettle, reacted at 160°C for 6 h, after the reaction was completed, washed with water, centrifuged, dried, and calcined at 800°C for 6 h to obtain a composite powder; (3) 99 g of carbon powder, 1 g of composite powder and 30 mL of anhydrous ethanol were uniformly mixed, ball-milled at 400 rpm for 12 h to obtain a mixed slurry, and then the mixed slurry was transferred to a cold isostatic pressing mold after being spray granulated (inlet temperature 240°C, outlet temperature 105°C) to obtain a green body, which was placed in a sintering furnace and sintered at 50 MPa and 1200°C for 6 h, and then machined after cooling to room temperature to obtain a composite target material; (4) The GCr15 bearing steel was placed in anhydrous alcohol and ultrasonically cleaned for 60 min, dried, and then placed on a sample table of a four-target closed field unbalanced magnetron sputtering device, and the door was closed to vacuumize to below 1x10Pa, argon flow was set to 100 sccm, working pressure was set to 1.0 Pa, target voltage pulse width of a high-power pulsed magnetron sputtering power source was set to 4 μs, average power was set to 8 kW, and negative bias power source was set to -100 V, and Ti metal target material was sputtered for 20 min; after deposition, argon flow was set to 100 sccm, nitrogen flow was set to 60 sccm, working pressure was set to 1.0 Pa, target voltage pulse width of the high-power pulsed magnetron sputtering power source was set to 4 μs, average power was set to 8 kW, and negative bias power source was set to -100 V, and Ti metal target material and the composite target material were sputtered for 30 min, and then cooled to obtain a graphite-like reinforced coating on the surface of the GCr15 bearing steel.

[0027] Comparative Example 1: The difference from Example 2 is that the composite target material in step (4) is replaced by a C target material, and the specific steps are as follows: (4) The GCr15 bearing steel was placed in anhydrous alcohol and ultrasonically cleaned for 45 min, dried, and then placed on a sample table of a four-target closed field unbalanced magnetron sputtering device, and the door was closed to vacuumize to below 1x10Pa, argon flow was set to 90 sccm, working pressure was set to 0.9 Pa, target voltage pulse width of a high-power pulsed magnetron sputtering power source was set to 3 μs, average power was set to 7 kW, and negative bias power source was set to -70 V, and Ti metal target material was sputtered for 15 min; after deposition, argon flow was set to 90 sccm, nitrogen flow was set to 40 sccm, working pressure was set to 0.9 Pa, target voltage pulse width of the high-power pulsed magnetron sputtering power source was set to 3 μs, average power was set to 7 kW, and negative bias power source was set to -70 V, and Ti metal target material and the C target material were sputtered for 30 min, and then cooled to obtain a graphite-like reinforced coating on the surface of the GCr15 bearing steel.

[0028] Comparative Example 2: The difference from Example 2 is that no carbon nanotubes are added during preparation of the composite powder, and the specific steps are as follows: (1) 1.5 g of molybdenum disulfide nanoparticles, 1.5 g of polycyclic aromatic hydrocarbon PAH and 700 mL of deionized water were mixed, 0.3 g of graphene oxide was added after stirring for 2 h, and stirring was continued until the mixture was uniform, then it was transferred to a Teflon-lined stainless steel autoclave, kept at 175°C for 21 h, to obtain molybdenum disulfide-graphene core-shell powder; (2) 1 g of ammonium molybdate, 1.5 g of thiourea and 1.5 g of molybdenum disulfide-graphene core-shell powder were weighed into 30 mL of deionized water, stirred uniformly and placed in a hydrothermal reactor, reacted at 155°C for 5 h, after the reaction was completed, washed with water, centrifuged, dried and calcined at 800°C for 5 h to obtain a composite powder; (3) 98 g of carbon powder, 2 g of the composite powder and 25 mL of anhydrous ethanol were uniformly mixed, ball milled at 300 rpm for 10 h to obtain a mixed slurry, then the mixed slurry was spray granulated (import temperature 210°C, export temperature 100°C) and transferred to a cold isostatic pressing mold, kept at 350 MPa for 15 min to obtain a green body, which was placed in a sintering furnace, kept at 35 MPa and 1100°C for 5 h, cooled to room temperature and then machined to obtain a composite target material; (4) GCr15 bearing steel was taken, ultrasonically cleaned in anhydrous alcohol for 45 min, dried to obtain pretreated GCr15 bearing steel, and placed on the sample table of a four-target closed field unbalanced magnetron sputtering device, vacuumed to below 1×10 Pa after closing the door, set argon flow rate to 90 sccm, working gas pressure to 0.9 Pa, target voltage pulse width of high-power pulsed magnetron sputtering power source to 3 μs, average power to 7 kW and negative bias power source to -70 V, sputtered Ti metal target material for 15 min; after the deposition was completed, set argon flow rate to 90 sccm, nitrogen flow rate to 40 sccm, working gas pressure to 0.9 Pa, target voltage pulse width of high-power pulsed magnetron sputtering power source to 3 μs, average power to 7 kW and negative bias power source to -70 V, sputtered Ti metal target material and the composite target material for 30 min, and cooled to obtain a GCr15 bearing steel surface graphite-like reinforced coating.

[0029] Comparative Example 3: The difference from Example 2 is that the composite powder in step (3) is replaced by molybdenum disulfide-graphene core-shell powder, and the specific steps are as follows: (3) 98 g of carbon powder, 2 g of molybdenum disulfide-graphene core-shell powder and 25 mL of anhydrous ethanol were uniformly mixed, ball milled at 300 rpm for 10 h to obtain a mixed slurry, then the mixed slurry was spray granulated (import temperature 210°C, export temperature 100°C) and transferred to a cold isostatic pressing mold, kept at 350 MPa for 15 min to obtain a green body, which was placed in a sintering furnace, kept at 35 MPa and 1100°C for 5 h, cooled to room temperature and then machined to obtain a composite target material; (4) GCr15 bearing steel was placed in anhydrous alcohol, ultrasonically cleaned for 45 min, dried, and obtained as pretreated GCr15 bearing steel, and was placed on a sample table of a four-target closed field unbalanced magnetron sputtering device, and was vacuumed to less than 1*10 Pa, argon flow rate was set to 90 sccm, working pressure was set to 0.9 Pa, target voltage of high power pulse magnetron sputtering power supply was set to 3 μs, average power was set to 7 kW, and negative bias power supply was set to -70 V, Ti metal target material was used for sputtering, and deposition time was 15 min; after deposition, argon flow rate was set to 90 sccm, nitrogen flow rate was set to 40 sccm, working pressure was set to 0.9 Pa, target voltage of high power pulse magnetron sputtering power supply was set to 3 μs, average power was set to 7 kW, and negative bias power supply was set to -70 V, Ti metal target material and composite target material were used for sputtering, and deposition time was 30 min, and cooling was performed, and a graphite-like enhanced coating on the surface of the GCr15 bearing steel was obtained.

[0030] Comparative Example 4: The difference from Example 2 is that the molybdenum disulfide-graphene core-shell powder is replaced by a mixed powder of molybdenum disulfide and graphene, and the specific steps are as follows: (1) 1 g of ammonium molybdate, 1.5 g of thiourea, 0.5 g of carbon nanotubes, 1.24 g of molybdenum disulfide nanoparticles, and 0.26 g of graphene oxide were placed in 30 mL of deionized water, stirred uniformly, and then placed in a hydrothermal reaction kettle, reacted at 155°C for 5 h, after the reaction was completed, washed with water, centrifuged, dried, and calcined at 800°C for 5 h, and a composite powder was obtained; (2) 98 g of carbon powder, 2 g of composite powder, and 25 mL of anhydrous ethanol were uniformly mixed, ball milled at 300 rpm for 10 h to obtain a mixed slurry, and then the mixed slurry was spray granulated (import temperature 210°C, export temperature 100°C) and transferred to a cold isostatic pressing mold, and was pressed at 350 MPa for 15 min to obtain a green body, and the green body was placed in a sintering furnace and sintered at 35 MPa and 1100°C for 5 h, and after cooling to room temperature, machining was performed to obtain a composite target material; (3) Taking GCr15 bearing steel, placing in anhydrous alcohol, ultrasonic cleaning for 45 min, drying, obtaining pretreated GCr15 bearing steel, and placing it on the sample table of a four-target closed field unbalanced magnetron sputtering device, vacuumizing to less than 1*10Pa, setting argon flow rate 90sccm, working gas pressure 0.9Pa, target voltage pulse width 3μs, average power 7kW and negative bias power -70V of high power pulse magnetron sputtering power supply, sputtering target material is Ti metal target material, deposition time is 15min; after deposition, setting argon flow rate 90sccm, nitrogen flow rate 40sccm, working gas pressure 0.9Pa, target voltage pulse width 3μs, average power 7kW and negative bias power -70V of high power pulse magnetron sputtering power supply, sputtering target material Ti metal target material and composite target material, deposition time is 30min, cooling, obtaining GCr15 bearing steel surface graphite-like enhanced coating.

[0031] Performance test Coating nano-hardness: determined by using a micro Vickers hardness tester (load 50gf, pressure holding time 15s), before testing, embedding and polishing the sample to mirror surface to avoid substrate interference, selecting 5 different areas of each sample for measurement, and taking average value; Film base bonding force: determined by using a scratch method (WS-2005 type scratch tester), with 10N / min linear increasing load to scratch the coating surface, testing 3 times for each sample group, and taking average value; Fracture toughness: determined according to GB / T 4161-2007 (metal materials, plane strain fracture toughness KIC test method); Coating friction coefficient: determined according to GB / T 12444-2006 (metal materials, wear test method), using a ball-disc type friction and wear testing machine (GCr15 steel ball, diameter 6mm, load 5N, rotation speed 200rpm, sliding distance 100m) to conduct experiment, calculating friction coefficient, and the above test results are shown in Table 1.

[0032] Table 1 Performance test results Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Nano-hardness (GPa) 40 42 41 32 37 38 35 Bonding force (N) 65 68 66 50 58 60 52 fracture toughness (MPa-m 1 / 2 )]> 5.2 5.5 5.3 3.8 4.1 4.5 3.9 Friction coefficient 0.08 0.07 0.08 0.14 0.10 0.09 0.11 Data analysis: From the test data of examples 1-3, it can be seen that the graphite-like reinforced coating prepared by the present application exhibits excellent comprehensive performance. In terms of mechanical properties, the coating has high hardness and good fracture toughness; the bonding strength test results show that the coating has a firm bonding strength with the substrate; in terms of tribological performance, the coating exhibits extremely low friction coefficient, which is mainly due to the unique "sandwich" structure design of the composite powder. The molybdenum disulfide nanoparticles as the core provide the basic lubrication performance, the intermediate graphene layer realizes efficient interlayer slip, and the outermost porous molybdenum disulfide coating structure ensures good interface bonding with other components. This sandwich structure, in the friction process, the outer porous molybdenum disulfide first undergoes shear deformation, exposing the intermediate graphene lubricating layer, while the internal molybdenum disulfide core serves as a reserve lubricating phase for continuous supply, so that the coating has good toughness and friction reduction performance while maintaining high hardness, meeting the requirements of the surface of bearing steel for integrated strength and toughness.

[0033] From the comparative data of examples 1 and comparative example 1, it can be seen that the coating prepared by using the composite target exhibits significantly superior comprehensive performance, which is mainly due to the unique "sandwich" structure formed by the molybdenum disulfide-graphene core-shell structure in the composite target and the porous molybdenum disulfide peripheral coating. In the process of magnetron sputtering, this composite structure is maintained and uniformly distributed in the coating. The inner core of molybdenum disulfide provides basic lubrication performance, the intermediate graphene layer realizes efficient interlayer slip through its two-dimensional planar structure, and the outer porous molybdenum disulfide ensures good interface bonding with other components.

[0034] From the performance comparison of example 2 and comparative example 2, it can be seen that the introduction of carbon nanotubes in the composite powder and the synergistic effect of the core-shell structure significantly improve the comprehensive performance of the coating. On the one hand, the carbon nanotubes form a three-dimensional network structure in the composite material, which simultaneously improves the mechanical properties through load transfer and crack bridging; at the same time, the π-π stacking interaction between carbon nanotubes and graphene enhances the interface bonding strength of the lubricating phase; on the other hand, the carbon nanotubes penetrate the porous structure formed by the outer porous molybdenum disulfide, which not only improves the load bearing capacity of the coating, but also provides storage space for the lubricant. Most importantly, the outer porous structure first participates in the contact, and then gradually releases the internal lubricant, realizing long-term and continuous release of the internal lubricant, thereby achieving a balance between excellent tribological performance and mechanical properties.

[0035] From the performance comparison of Example 2 and Comparative Examples 3, 4, it can be seen that the unique "sandwich" structure design of the composite powder has a decisive influence on the coating performance. In the microstructure of the composite powder, the molybdenum disulfide core provides basic lubricating performance through its layered crystal structure, the intermediate graphene layer reduces the friction coefficient through the plane slip effect of sp2 hybrid carbon atoms, and the outermost porous molybdenum disulfide coating structure not only enhances the interface bonding with other components, but also controls the controlled release of the internal lubricating components, thereby showing that, compared with Comparative Example 3 (without peripheral porous structure coating) and Comparative Example 4 (without internal core-shell structure), the coating not only maintains excellent friction reduction performance, but also significantly improves mechanical performance, showing the unique advantages of the "sandwich" structure design in optimizing the comprehensive performance of the coating.

[0036] It should be understood by those of ordinary skill in the art that the above discussion of any of the embodiments is merely exemplary and is not intended to suggest that the scope of the present application is limited to these examples; under the idea of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above. In order to be brief, they are not provided in detail.

Claims

1. A graphite-like reinforced coating on the surface of GCr15 bearing steel, characterized in that, It includes a bonding layer and a wear-resistant lubricating layer, which are deposited sequentially on the bearing steel surface from the inside out by magnetron sputtering.

2. A method for preparing a graphite-like reinforced coating on the surface of GCr15 bearing steel according to claim 1, characterized in that, Includes the following steps: S11 Matrix Pre-cleaning: The matrix is ​​cleaned to obtain a pretreated matrix; S12 Deposition Bonding Layer: The sputtering target is a Ti metal target or a Cr metal target, and the deposition time is 10-20 min; S13 Deposition of Wear-Resistant Lubricating Layer: The sputtering target is a Ti metal target and a composite target, and the deposition time is 10-30 min; The preparation steps of the composite target material in step S13 are as follows: S21: Molybdenum disulfide nanoparticles, polycyclic aromatic hydrocarbons (PAH), deionized water, and graphene oxide are mixed and kept at 170-180℃ for 20-22 hours to obtain molybdenum disulfide-graphene core-shell powder. S22: Ammonium molybdate, thiourea, carbon nanotubes and molybdenum disulfide-graphene core-shell powder are placed in deionized water and reacted at 150-160℃ for 4-6 hours. After the reaction is completed, the powder is purified and calcined to obtain the composite powder. S23: Carbon powder, composite powder and anhydrous ethanol are uniformly mixed and ball-milled to obtain a mixed slurry. The mixture is then subjected to spray granulation, cold isostatic pressing, heat preservation sintering and machining to obtain a composite target material.

3. The preparation method according to claim 2, characterized in that, The process parameters for the deposition bonding layer in step S12 are as follows: argon flow rate 80-100 sccm, working pressure 0.8-1.0 Pa, high-power pulsed magnetron sputtering power supply target voltage pulse width 1-4 μs, average power 5-8 kW, and negative bias power supply -30~-100 V.

4. The preparation method according to claim 2, characterized in that, The process parameters for depositing the wear-resistant lubricating layer in step S13 are as follows: argon flow rate 80-100 sccm, nitrogen flow rate 20-60 sccm, working pressure 0.8-1.0 Pa, high-power pulsed magnetron sputtering power supply target voltage pulse width 1-4 μs, average power 5-8 kW, and negative bias power supply -30~-100 V.

5. The preparation method according to claim 2, characterized in that, In step S21, the ratio of molybdenum disulfide nanoparticles, polycyclic aromatic hydrocarbons (PAH), deionized water, and graphene oxide is 1-2g:1-2g:500-800mL:0.2-0.4g.

6. The preparation method according to claim 2, characterized in that, In step S22, the ratio of ammonium molybdate, thiourea, carbon nanotubes, molybdenum disulfide-graphene core-shell powder, and deionized water is 1g:1-2g:0.5g:1-2g:30mL.

7. The preparation method according to claim 2, characterized in that, The ratio of carbon powder, composite powder, and anhydrous ethanol used in step S23 is 95-99g:1-5g:20-30mL.

8. The preparation method according to claim 2, characterized in that, The parameters for spray granulation in step S23 are: atomizing disc rotation speed of 8000-12000 rpm, inlet temperature of 180-240℃, and outlet temperature of 80-105℃.

9. The preparation method according to claim 2, characterized in that, The parameters for cold isostatic pressing in step S23 are 300-400 MPa and pressure holding time is 10-20 min.

10. The preparation method according to claim 2, characterized in that, The sintering parameters in step S23 are 20-50 MPa, 900-1200℃, and holding time of 3-6 h.