Environment-adaptive composite solid lubricant and application thereof

Abstract

The invention discloses an environment self-adaptive composite solid lubricant. The environment self-adaptive composite solid lubricant is prepared from the following components in percentage by mass: 80 to 90 percent of Sn-Ag-Cu ternary alloy, 5 to 10 percent of Mo2TiAlC2 and 5 to 10 percent of WS2. On the basis, the invention further provides a vehicle hub bolt fastening sleeve adopting the environment self-adaptive composite solid lubricant, the sleeve comprises a sleeve body and a sleeve inner layer located on the inner wall of the sleeve, the sleeve inner layer is provided with a bionic texture flow channel, and the sleeve inner layer and the bionic texture flow channel of the sleeve inner layer are prepared through the metal 3D printing technology; the bionic texture flow channel of the inner layer of the sleeve is filled with the environment self-adaptive composite solid lubricant, the self-adaptive performance and the mechanical performance of the sleeve can be coordinated and unified, the lubricating effect is effective and reliable, loss of the lubricant in a non-working state is avoided, and the service life of the sleeve is prolonged. The problems that an existing sleeve is high in friction and abrasion and short in service life are solved.

Description

Technical Field

[0001] This invention belongs to the field of materials, specifically relating to an environmentally adaptive composite solid lubricant and its application. Background Technology

[0002] With the rapid development of the automotive industry and the gradual expansion of the new energy vehicle market, the production and ownership of automobiles are constantly increasing, which puts higher demands on the performance of various automotive components. Among them, wheel hub bolt fastening sleeves are commonly used fastening tools in automotive production, assembly, and after-sales maintenance. They need to be used repeatedly for a long time and frequently withstand friction and impact from high-intensity torque. Their quality and performance directly affect the fastening effect of automotive wheel hub bolts, wheel hub safety, and assembly efficiency of the production line.

[0003] Currently, traditional automotive wheel hub fastening sleeves are mainly made of alloy steel and tool steel. Although surface treatment can give them a certain degree of strength and toughness, this also increases manufacturing costs, limiting their application in large-scale production. Furthermore, they are prone to wear, deformation, and even breakage under extreme operating conditions, and the long-term wear resistance of the material still needs improvement. This not only affects the tightening effect and appearance of the bolts but may also pose vehicle safety hazards and increase replacement frequency and costs.

[0004] In existing wear-resistant lubrication technologies, wear-resistant composite coating materials achieve their function through the synergistic combination of a "hard phase + soft phase." High-hardness ceramic particles are often used as the hard phase to enhance hardness and wear resistance, while tough materials such as eutectic high-entropy alloys are combined as the soft phase, forming an "alternating hard and soft phase" structure to hinder crack propagation and enhance impact resistance. Composite solid lubricants use layered materials such as graphite and molybdenum disulfide as the main lubricant, utilizing their low shear force characteristics to reduce friction. Auxiliary components such as binders and film-forming agents are added to ensure the adhesion of the lubricant and the continuity of the lubricating film. However, applying these technologies to fastening sleeves requires specific processes. Wear-resistant composite coatings are often achieved through laser cladding or thermal spraying: In laser cladding, high-entropy alloys and ceramic powders are first mixed and ball-milled, then clad layer by layer after preheating the substrate and undergoing annealing heat treatment; thermal spraying involves heating and melting the material powder and directly spraying it onto the sleeve surface. Composite solid lubricants are often produced using a coating process, in which the coating lubricant is filled into the texture and then cooled and cured to form a lubricating layer.

[0005] However, many shortcomings and challenges remain in practical applications. Regarding wear-resistant composite coatings, the large phase differences between ceramic particles and the metal substrate lead to poor compatibility and wettability, easily resulting in insufficient interfacial bonding strength and potential coating peeling. Some processes, such as high-temperature aluminizing, are limited by part size, making it difficult to handle irregularly shaped or large sleeves, and their efficiency is low. Furthermore, improper control of parameters such as powder particle size and powder feed rate can cause quality problems such as high coating porosity and insufficient hardness. The drawbacks of composite solid lubricants include a high coefficient of friction, increasing energy consumption; weak thermal conductivity, leading to heat accumulation from friction and increased sleeve temperature, affecting service life; and the difficulty in self-repairing after solid lubricant film ruptures, requiring frequent maintenance and increasing operating costs and complexity. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an environmentally adaptive composite solid lubricant and a sleeve using such a composite solid lubricant to address the shortcomings of the prior art. This invention can achieve a synergistic unity of the sleeve's adaptive performance and mechanical properties, provide effective and reliable lubrication, and avoid lubricant loss when not in operation, thus solving the problems of high friction, high wear, and short service life of existing sleeves.

[0007] The technical solution adopted by the present invention to solve the above-mentioned problems is as follows:

[0008] An environmentally adaptive composite solid lubricant, comprising by mass percentage: 80-90 wt.% Sn-Ag-Cu ternary alloy, 5-10 wt.% Mo2TiAlC2, and 5-10 wt.% WS2.

[0009] The preparation method of the above-mentioned environmentally adaptive composite solid lubricant includes the following steps:

[0010] (1) Mix 80-90 wt.% Sn-Ag-Cu ternary alloy powder, 5-10 wt.% Mo2TiAlC2 powder and 5-10 wt.% nano WS2 powder by mass percentage, then ball mill until uniform, and obtain solid feed by cold isostatic pressing.

[0011] (2) The solid ingredients are hot-extruded into filaments and then atomized by a plasma rotating electrode to obtain Mo2TiAlC2-WS2-SAC composite solid spherical powder with a powder diameter of 30-50μm, which is the environmentally adaptive composite solid lubricant.

[0012] According to the above scheme, the mass percentage of each metal element in the Sn-Ag-Cu ternary alloy is Sn 96-97 wt.%, Ag 2.5-3 wt.%, and Cu 0.5-1 wt.%.

[0013] According to the above scheme, the particle size range of Sn-Ag-Cu ternary alloy powder is 20-38μm, and the purity is above 99%; the particle size range of Mo2TiAlC2 powder is 25-45μm, and the purity is above 95%; the particle size range of nano WS2 powder is 45-53nm, and the purity is above 95%.

[0014] According to the above scheme, the ball milling adopts a vacuum ball mill, the ball milling time is 2-6 hours, and the ball milling speed is 250-350 rpm.

[0015] According to the above scheme, the cold isostatic pressing process is as follows: the ball-milled raw material is placed in a mold and sealed, and mechanical vibration is used to make it tightly fill the mold. Then it is placed in a cold isostatic pressing equipment, and argon gas is introduced as a protective gas. The pressure is controlled at 200-250MPa and held for 20-40 minutes. After the compaction is completed, the pressure is released and the mold is demolded to obtain Mo2TiAlC2-WS2-SAC solid billet.

[0016] According to the above scheme, the process parameters for hot extrusion into filaments are as follows: argon gas is used for covering during operation, the working temperature is set to 220-240℃, the pressure is controlled at 400-450MPa, the extrusion speed is 3-8mm / s, and the diameter of the extruded filament is 2-4mm.

[0017] According to the above scheme, the plasma rotating electrode atomization process is as follows: the filament obtained after hot extrusion is inserted into the plasma atomization area of ​​the plasma rotating electrode atomization equipment. Argon gas is introduced as a protective gas and forms a conductive circuit with the plasma gun in the atomization chamber, generating high-temperature plasma that melts the filament and atomizes it into small droplets, which are then condensed into powder. The filament feed speed is 2-5 m / min, the filament rotation feed speed is 300-400 rpm, the melting temperature is 270-300℃, and the pressure of the atomizing gas is 4-6 MPa.

[0018] Based on the above, the present invention also provides a wheel hub bolt fastening sleeve for vehicles using the aforementioned environmentally adaptive composite solid lubricant. The sleeve includes a sleeve body and an inner sleeve layer located on the inner wall of the sleeve. The inner sleeve layer is provided with a biomimetic textured flow channel, and the inner sleeve layer and its biomimetic textured flow channel are prepared using metal 3D printing technology. The biomimetic textured flow channel of the inner sleeve layer is filled with the environmentally adaptive composite solid lubricant described in this invention.

[0019] According to the above scheme, the thickness of the inner layer of the sleeve is generally in the range of 1-4mm.

[0020] According to the above scheme, the cross-sections of both the sleeve body and the inner layer of the sleeve are regular hexagons, so the inner layer of the sleeve includes 6 inner side surfaces; the dimensions of the inner layer of the sleeve are compatible with those of the sleeve body.

[0021] According to the above scheme, each inner surface of the inner layer of the sleeve is provided with two rings of cylindrical holes, including an inner ring hole and an outer ring hole. Adjacent inner ring holes are connected by a flow channel, and adjacent outer ring holes are connected by a flow channel, thereby forming a biomimetic textured flow channel. The geometric parameters of the biomimetic textured flow channel are: hole depth is 0.5-0.6mm, the spacing between adjacent holes is 0.5-0.8mm, and the holes are preferably cylindrical with a diameter of 0.4-0.6mm.

[0022] Furthermore, the present invention provides an environmentally adaptive automotive wheel hub bolt fastening sleeve, the preparation method of which includes the following steps:

[0023] 1) The inner layer of the sleeve and its biomimetic textured flow channel were prepared using selective laser powder melting technology;

[0024] 2) The environmentally adaptive composite solid lubricant described in this invention is uniformly sprayed onto the surface of the inner layer of the sleeve using cold spraying technology, and then transferred to a vacuum melting furnace. After being evacuated, it is first heated to 350-400℃ and held for 90-120 minutes, then heated to 600-650℃ and held for 45-60 minutes to complete the melting process. After being allowed to cool slowly to room temperature, the inner layer of the sleeve is obtained after polishing, grinding, washing and drying.

[0025] 3) The inner layer of the sleeve and the sleeve body are self-lockingly assembled to obtain the environmentally adaptive vehicle wheel hub bolt fastening sleeve of the present invention.

[0026] According to the above scheme, in step 1), the sleeve body can be selected from commonly used specifications such as 17mm, 19mm, 21mm, and 23mm, and the hub fastening sleeve is made of high carbon steel or alloy steel. The corresponding inner layer of the sleeve can be obtained by changing the printing size parameters.

[0027] According to the above scheme, in step 1), 42CrMo alloy powder is used as the raw material powder for selective laser powder melting technology. Its particle size range is 15-53μm and its purity is above 95%. The process parameters for selective laser powder melting are: laser power of 280-300W, scanning speed of 0.5-1.5m / s, scanning spacing of 0.05-0.10mm, layer thickness of 0.02-0.06mm, and spot diameter of 40-60μm.

[0028] According to the above scheme, in step 2), the working gas for cold spraying is helium, the working pressure is 3-5 MPa, and the working gas temperature is 200-220℃.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] (1) This invention uses a novel MAX phase two-dimensional material Mo2TiAlC2 and nano WS2 to form an environmentally adaptive composite solid lubricant with Sn-Ag-Cu ternary alloy. The combination of Sn-Ag-Cu ternary alloy powder, Mo2TiAlC2 two-dimensional material powder and WS2 nano powder is different from the single component of traditional solid lubricants. It achieves performance improvement through the synergistic effect of multiple phases. Sn-Ag-Cu ternary alloy powder serves as the main base. Its low melting point allows the lubricant to spread rapidly, forming a continuous and dense lubricating film, effectively reducing the roughness of the friction pair surface. At the same time, the internal slip mechanism endows it with good lubrication load-bearing capacity, preventing the lubricating layer from peeling off under reciprocating impact. Mo2TiAlC2, as the transition reinforcing phase, has a unique layered structure with excellent compatibility. It can strengthen the bonding force between the powder and WS2 through interfacial diffusion, and can also self-repair microcracks during friction, improving the stability of the lubricating layer. As a lubricating component, WS2, relying on the van der Waals forces between layers, slides rapidly under shearing action, significantly reducing the coefficient of friction. Its nanoscale sheets can also fill surface micro-defects, forming a mirror-like effect, further optimizing the lubrication effect.

[0031] Compatibility issues have always been a challenge between materials. Sn-Ag-Cu ternary alloys and WS2 differ in chemical properties and crystal structure, making them prone to interfacial separation under normal conditions due to poor wettability, thus affecting the bonding and lubrication effect. However, the novel MAX phase two-dimensional material Mo2TiAlC2 possesses a unique chemical bonding mode that combines metallic and covalent bonds. When combined with nano-WS2 and Sn-Ag-Cu ternary alloy powders to form a composite solid lubricant, it can ensure a firm connection with the inner layer of the sleeve.

[0032] (2) The present invention uses plasma rotating electrode atomization method to ensure the uniformity of material particles. High-purity argon gas is filled into the cavity and a positive pressure environment is maintained. On the one hand, oxygen is isolated to prevent powder oxidation and modification. On the other hand, the airflow disturbance promotes particle refinement, which makes it easier for the composite solid lubricant described in the present invention to be tightly distributed on the inner layer of the sleeve. This ensures that the composite lubricant is tightly bound to the inner layer of the sleeve and its flow channel when the sleeve is working, so that the lubrication effect of the solid lubricant is effective and reliable.

[0033] (3) This invention employs cold spraying and vacuum melting infiltration technology. Pre-treatment cleaning removes the dense oxide layer on the inner surface of the 42CrMo sleeve, and the plastic deformation generated by high-speed particle impact achieves a tight bond between the powder and the substrate (i.e., the inner layer of the sleeve and its flow channels), avoiding detachment due to the high density and hardness of the substrate. By adjusting the melting infiltration temperature distribution according to the different melting points of the multiphase composite solid lubricant, component segregation is avoided. Slow cooling in the furnace prevents thermal stress from causing interface defects in the coating formed on the inner surface of the sleeve by the composite solid lubricant.

[0034] (4) This invention employs an inner sleeve layer containing a biomimetic textured flow channel. The specific flow channel structure enables the sleeve to achieve a synergistic unity of adaptive performance and mechanical properties. In conventional understanding, solid lubricants are difficult to migrate actively once coated. However, the biomimetic textured flow channel of this invention, through the synergy of structure and materials, allows the migration of lubricant to no longer depend on external power, but to achieve autonomous response by relying on the working conditions themselves. When the inner sleeve layer rubs against the mating parts, local high temperatures are generated in the contact area. The Sn-Ag-Cu ternary alloy phase in the composite solid lubricant will soften locally due to the temperature rise and flow to the high-temperature area under the action of thermal convection. The mechanical vibration generated during the friction process provides a driving force for the lubricant, causing the WS2 lubricating nanosheet layer in the lubricant to migrate directionally along the flow channel with the vibration, filling the micro-pits caused by wear at the interface. When the temperature drops, the solid lubricant re-solidifies, which can temporarily seal the micro-grooves and prevent the lubricant from being lost in the non-working state, thereby achieving environmental adaptation and effectively improving the life of the sleeve.

[0035] (5) The present invention adopts a self-locking assembly method of metal 3D printing with biomimetic textured flow channel inner layer and machined fastening outer layer of sleeve. On the one hand, it ensures the overall tightness of the fastening sleeve. On the other hand, when the inner layer of the sleeve reaches the end of its working service life, only the inner layer of the sleeve can be replaced, thereby saving processing and production materials and further achieving energy saving and environmental protection. Attached Figure Description

[0036] Figure 1 This is a physical image of the adaptive automotive wheel hub bolt fastening sleeve described in this invention.

[0037] Figure 2 These are microscopic feature images of the environmentally adaptive composite solid lubricant described in this invention.

[0038] Figure 3 This is a schematic diagram of the sleeve structure.

[0039] Figure 4 It is a schematic diagram of the biomimetic textured flow channel and its inner and outer ring holes.

[0040] Figure 5 This is a schematic diagram of the fastening assembly of the inner layer of the sleeve and the sleeve body. 1 indicates that the outer surface of the inner layer of the sleeve has a protrusion that engages with the groove of the sleeve body to achieve a self-locking assembly.

[0041] Figure 6 This is the friction coefficient curve obtained from the experimental process of Example 3.

[0042] Figure 7 This is the microstructure of the worn surface of the sample in Example 3.

[0043] Figure 8 This is the friction coefficient curve obtained from the experimental process of Example 4.

[0044] Figure 9 This is the microstructure of the worn surface of the sample in Example 4. Detailed Implementation

[0045] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the present invention is not limited to the following embodiments.

[0046] In the following examples, the Sn-Ag-Cu ternary alloy powder has a particle size range of 20-38 μm and a purity of over 99%; the Mo2TiAlC2 powder has a particle size range of 25-45 μm and a purity of over 95%; the nano-WS2 powder has a particle size range of 45-53 nm and a purity of over 95%; and the proportions of each metal element in the Sn-Ag-Cu ternary alloy powder are Sn 96.5 wt.%, Ag 3 wt.%, and Cu 0.5 wt.%.

[0047] Example 1

[0048] A method for preparing an environmentally adaptive composite solid lubricant, comprising the following specific steps:

[0049] (1) Sn-Ag-Cu ternary alloy powder, Mo2TiAlC2 powder and nano WS2 powder were mixed in a vibratory mixer at a weight ratio of 90wt.%, 5wt.%, and 5wt.%, respectively, for 30 min. Then, the mixture was placed in a vacuum ball mill and ball-milled at 250 rpm for 4 h. The mixture was then uniformly sealed in a mold and mechanically vibrated to make the powder compact. The mixture was then placed in a cold isostatic pressing device with argon as the protective gas and the pressure was controlled at 200 MPa. After holding the pressure for 30 min, the pressure was released and the mold was demolded to obtain Mo2TiAlC2-WS2-SAC solid billet.

[0050] (2) The above Mo2TiAlC2-WS2-SAC solid billet is placed in a hot extruder, the working environment is covered with argon gas, the working temperature is set to 230℃, the pressure is controlled at 400MPa, the extrusion speed is 5mm / s, and the extruded wire with a diameter of about 3mm is produced.

[0051] (3) The above-mentioned filament is placed in the plasma atomization area of ​​the plasma rotating electrode atomization device to form a conductive circuit with the plasma gun in the atomization chamber. High-temperature plasma is generated to melt the filament and atomize it into small droplets, which are then condensed into powder to obtain Mo2TiAlC2-WS2-SAC composite solid spherical powder with a diameter of 30-50μm, which is an environmentally adaptive composite solid lubricant. The filament feed speed is 3m / min, the rod rotation feed speed is 300rpm, the melting temperature is 300℃, and the atomizing gas pressure is 4MPa.

[0052] Example 2

[0053] A method for preparing an environmentally adaptive composite solid lubricant, comprising the following specific steps:

[0054] (1) Sn-Ag-Cu ternary alloy powder, Mo2TiAlC2 powder and nano WS2 powder were mixed in a vibratory mixer at a weight ratio of 80wt.%, 10wt.%, and 10wt.%, respectively, for 40 min. Then, the mixture was placed in a vacuum ball mill and ball-milled at 350 rpm for 4 h. The mixture was then uniformly sealed in a mold and mechanically vibrated to make the mixed powder tightly filled. The mixture was then placed in a cold isostatic pressing equipment with argon as the protective gas and the pressure was controlled at 250 MPa. After holding the pressure for 30 min, the pressure was released and the mold was demolded to obtain Mo2TiAlC2-WS2-SAC solid billet.

[0055] (2) The above Mo2TiAlC2-WS2-SAC solid billet is placed in a hot extruder, the working environment is covered with argon gas, the working temperature is set to 230℃, the pressure is controlled at 450MPa, the extrusion speed is 5mm / s, and the extruded wire with a diameter of about 3mm is produced.

[0056] (3) The above-mentioned filament is placed in the plasma atomization area of ​​the plasma rotating electrode atomization device to form a conductive circuit with the plasma gun in the atomization chamber. High-temperature plasma is generated to melt the filament and atomize it into small droplets, which are then condensed into powder to obtain Mo2TiAlC2-WS2-SAC composite solid spherical powder with a diameter of 30-50μm, which is an environmentally adaptive composite solid lubricant. The filament feed speed is 3m / min, the rod rotation feed speed is 400rpm, the melting temperature is 300℃, and the atomizing gas pressure is 6MPa.

[0057] like Figure 2 The image shown is a microscopic feature image of the environmentally adaptive composite solid lubricant of the present invention. It is spherical with a size in the range of 10-30 μm.

[0058] Example 3

[0059] An environmentally adaptive automotive wheel hub bolt fastening sleeve includes a sleeve body and an inner sleeve layer located on the inner wall of the sleeve. Both the sleeve body and the inner sleeve layer have hexagonal cross-sections. The six inner surfaces of the inner sleeve layer are provided with biomimetic textured flow channels. The biomimetic textured flow channels of the inner sleeve layer are filled with an environmentally adaptive composite solid lubricant prepared in Example 1. The sleeve body is made of 19mm high-carbon steel; the inner sleeve layer is made of 42CrMo alloy with a thickness ranging from 1.53 to 3mm; the biomimetic textured flow channels are as follows... Figure 3 and Figure 4As shown, each inner surface of the inner layer of the sleeve has two rings of cylindrical holes, including an inner ring hole and an outer ring hole. Adjacent inner ring holes are connected by flow channels, and adjacent outer ring holes are connected by flow channels, thus forming a biomimetic textured flow channel. The geometric parameters of the biomimetic textured flow channel are: hole depth is 0.5mm, the spacing between adjacent holes is 0.8mm, and the hole diameter is 0.4mm.

[0060] The environmentally adaptive automotive wheel hub bolt fastening sleeve described in this embodiment is manufactured using the following steps:

[0061] 1) Using selective laser powder melting technology, a sleeve inner layer with a biomimetic textured flow channel that meets the above-mentioned dimensional parameters in this embodiment is obtained through multi-layer laser powder melting. Then, it is polished and ground, placed in an ultrasonic cleaner, cleaned with anhydrous ethanol, and dried. 42CrMo alloy powder is used as raw material, with a particle size range of 30-46μm and a purity of over 95%. The laser power is 300W, the scanning speed is 1m / s, the scanning interval is 0.08mm, the layer thickness is 0.04mm, and the spot diameter is 55μm.

[0062] 2) The environmentally adaptive composite solid lubricant prepared in Example 1 was uniformly sprayed onto the surface of the inner layer of the sleeve using cold spraying technology. The working gas for spraying was helium, the working pressure was set to 3.5 MPa, and the working gas temperature was set to 210°C. When using the cold spraying equipment for spraying, it was ensured that the spray gun could move smoothly to ensure that a uniform and dense coating could be formed. After spraying, it was transferred to a vacuum melting furnace (ensuring that the biomimetic texture flow channel was filled with the environmentally adaptive composite solid lubricant). After being evacuated to a vacuum, it was first heated to 360°C and held for 120 min, then heated to 650°C and held for 60 min to complete the melting process, and then slowly cooled to room temperature.

[0063] 3) Place the above-mentioned infiltrated inner sleeve on a polishing machine, add metal polishing paste, and polish for 20 minutes (after polishing, the non-biomimetic textured area of ​​the inner sleeve will reveal 42CrMo alloy). Then, place it in an ultrasonic cleaner with anhydrous ethanol for 20 minutes, and after drying, perform a self-locking assembly with the machined sleeve body to obtain an environmentally adaptive automotive wheel hub bolt fastening sleeve. The self-locking assembly diagram is shown below. Figure 5 As shown.

[0064] The inner layer material of the sleeve prepared in Example 3 was cut into blocks and sampled. Reciprocating dry friction tests were performed on these blocks using a multi-functional friction testing machine. A ball-plate grinding pair was used, with the grinding balls made of GCr15 steel. The sample blocks were 20mm long × 10mm wide × 5mm thick. The test load was 20N, the test temperature was 25-30℃, and the reciprocating frequency was 1Hz. Each sample underwent three trials, and the average friction coefficient per minute was used as the experimental result. Each trial lasted 30 minutes. The microstructure of the worn surface of the sample was then observed using an electron probe microscope. The friction coefficient curves obtained during the experiment are shown below. Figure 6 As shown, the microstructure of the worn surface of the sample is as follows. Figure 7 As shown.

[0065] Based on the above performance tests and microscopic morphology observations, the friction coefficient of the inner layer material of the sleeve is low, and the surface wear damage is slight.

[0066] In the reciprocating dry friction test between the spherical and planar surfaces, the stable average sliding friction coefficient of the inner layer surface of the sleeve was 0.44 after 30 minutes, demonstrating good friction reduction and wear resistance. In contrast, the ordinary 42CrMo surface exhibited a friction coefficient of 0.58 under dry friction, and obvious scratches were observed on the surface.

[0067] Example 4

[0068] An environmentally adaptive automotive wheel hub bolt fastening sleeve includes a sleeve body and an inner sleeve layer located on the inner wall of the sleeve. The inner sleeve layer is provided with a biomimetic textured flow channel. The biomimetic textured flow channel of the inner sleeve layer is filled with an environmentally adaptive composite solid lubricant prepared in Example 1. The sleeve body is made of 19mm high-carbon steel; the inner sleeve layer is made of 42CrMo alloy with a thickness in the range of 1.53-3mm; the biomimetic textured flow channel is also... Figure 3 and Figure 4 As shown, the hole depth is 0.6 mm, the spacing between adjacent holes is 0.6 mm, and the hole radius is 0.6 mm.

[0069] The environmentally adaptive automotive wheel hub bolt fastening sleeve described in this embodiment is manufactured using the following steps:

[0070] 1) Using selective laser powder melting technology, a sleeve inner layer with a biomimetic textured flow channel that meets the above-mentioned dimensional parameters in this embodiment is obtained through multi-layer laser powder melting. Then, it is polished and ground, placed in an ultrasonic cleaner, cleaned with anhydrous ethanol, and dried. 42CrMo alloy powder is used as raw material, with a particle size range of 30-46μm and a purity of over 95%. The laser power is 280W, the scanning speed is 1m / s, the scanning interval is 0.08mm, the layer thickness is 0.04mm, and the spot diameter is 55μm.

[0071] 2) The environmentally adaptive composite solid lubricant prepared in Example 2 was uniformly sprayed onto the surface of the inner layer of the sleeve using cold spraying technology. The working gas for spraying was helium, the working pressure was set to 3.5 MPa, and the working gas temperature was set to 210°C. When using the cold spraying equipment for spraying, it was ensured that the spray gun could move smoothly to ensure that a uniform and dense coating could be formed. After spraying, it was transferred to a vacuum melting furnace. After being evacuated, it was first heated to 360°C and held for 120 min, then heated to 650°C and held for 60 min to complete the melting process. It was then slowly cooled to room temperature.

[0072] 3) Place the inner layer of the sleeve that has been melted and infiltrated on a polishing machine, add metal polishing paste and polish for 20 minutes. Then, put it into an ultrasonic cleaner with anhydrous ethanol for 20 minutes and dry it. After that, it is self-locked and assembled with the machined outer layer of the sleeve to obtain an environmentally adaptive automotive wheel hub bolt fastening sleeve.

[0073] The inner layer material of the sleeve prepared in Example 4 was cut into blocks and sampled. Reciprocating dry friction tests were performed on these blocks using a multi-functional friction testing machine. The test conditions and methods were the same as in Example 3. The friction coefficient curves obtained during the experiment are shown below. Figure 8 As shown, the microstructure of the worn surface of the sample is as follows. Figure 9 As shown.

[0074] Based on the above performance tests and microscopic morphology observations, the friction coefficient of the inner layer material of the sleeve is low, and the surface wear damage is slight.

[0075] In the reciprocating dry friction test between the spherical and planar surfaces, the stable average sliding friction coefficient of the inner layer material of the sleeve was 0.43 after 30 minutes, demonstrating good friction reduction and wear resistance. In contrast, the ordinary 42CrMo surface exhibited a friction coefficient of 0.58 under dry friction, and obvious scratches were observed on the surface.

[0076] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. An environmentally adaptive composite solid lubricant, characterized in that, Its composition, by mass percentage, includes: 80-90 wt.% Sn-Ag-Cu ternary alloy, 5-10 wt.% Mo2TiAlC2, and 5-10 wt.% WS2.

2. The preparation method of the environmentally adaptive composite solid lubricant according to claim 1, characterized in that, Includes the following steps: (1) Mix 80-90 wt.% Sn-Ag-Cu ternary alloy powder, 5-10 wt.% Mo2TiAlC2 powder and 5-10 wt.% nano WS2 powder by mass percentage, then ball mill until uniform, and obtain solid feed by cold isostatic pressing. (2) The solid ingredients are hot-extruded into filaments and then atomized by a plasma rotating electrode to obtain Mo2TiAlC2-WS2-SAC composite solid spherical powder with a powder diameter of 30-50μm, which is the environmentally adaptive composite solid lubricant.

3. The method for preparing an environmentally adaptive composite solid lubricant according to claim 2, characterized in that, The raw material Sn-Ag-Cu ternary alloy powder has a particle size range of 20-38 μm and a purity of over 99%; the Mo2TiAlC2 powder has a particle size range of 25-45 μm and a purity of over 95%; the nano WS2 powder has a particle size range of 45-53 nm and a purity of over 95%; the mass percentage of each metal element in the Sn-Ag-Cu ternary alloy is Sn 96-97 wt.%, Ag 2.5-3 wt.%, and Cu 0.5-1 wt.%.

4. The preparation method of an environmentally adaptive composite solid lubricant according to claim 2, characterized in that, The cold isostatic pressing process is as follows: the ball-milled raw material is placed in a mold and sealed, and mechanical vibration is used to make it tightly fill the mold. Then it is placed in a cold isostatic pressing equipment, and argon gas is introduced as a protective gas. The pressure is controlled at 200-250MPa and held for 20-40 minutes. After the pressing is completed, the pressure is released and the mold is demolded to obtain Mo2TiAlC2-WS2-SAC solid billet.

5. The method for preparing an environmentally adaptive composite solid lubricant according to claim 2, characterized in that, The process parameters for hot extrusion into filaments are as follows: argon gas is used for covering during operation, the working temperature is set to 220-240℃, the pressure is controlled at 400-450MPa, the extrusion speed is 3-8mm / s, and the diameter of the extruded filament is 2-4mm. The plasma rotating electrode atomization process is as follows: the filament obtained after hot extrusion is inserted into the plasma atomization area of ​​the plasma rotating electrode atomization equipment. Argon gas is introduced as a protective gas and forms a conductive circuit with the plasma gun in the atomization chamber, generating high-temperature plasma that melts the filament, atomizes it into droplets, and then condenses it into powder. The filament feed speed is 2-5 m / min, the filament rotation feed speed is 300-400 rpm, the melting temperature is 270-300℃, and the pressure of the atomizing gas is 4-6 MPa.

6. An environmentally adaptive automotive wheel hub bolt fastening sleeve, characterized in that, The device includes a sleeve body and an inner sleeve layer located on the inner wall of the sleeve body. The inner sleeve layer is provided with a biomimetic textured flow channel. The inner sleeve layer and its biomimetic textured flow channel are prepared using metal 3D printing technology. The biomimetic textured flow channel of the inner sleeve layer is filled with the environmentally adaptive composite solid lubricant as described in claim 1.

7. The vehicle wheel hub bolt fastening sleeve according to claim 6, characterized in that, The thickness of the inner layer of the sleeve ranges from 1 to 4 mm.

8. The automotive wheel hub bolt fastening sleeve according to claim 6, characterized in that, Each inner surface of the sleeve inner layer has two rings of cylindrical holes, including an inner ring hole and an outer ring hole. Adjacent inner ring holes are connected by flow channels, and adjacent outer ring holes are connected by flow channels, thus forming a biomimetic textured flow channel. The geometric parameters of the biomimetic textured flow channel are: hole depth of 0.5-0.6mm, spacing between adjacent holes of 0.5-0.8mm, and hole diameter of 0.4-0.6mm.

9. The method for preparing the environmentally adaptive automotive wheel hub bolt fastening sleeve according to claim 6, characterized in that, Includes the following steps: 1) The inner layer of the sleeve and its biomimetic textured flow channel were prepared using selective laser powder melting technology; 2) The environmentally adaptive composite solid lubricant described in this invention is uniformly sprayed onto the surface of the inner layer of the sleeve using cold spraying technology, and then transferred to a vacuum melting furnace. After being evacuated, it is first heated to 350-400℃ and held for 90-120 minutes, then heated to 600-650℃ and held for 45-60 minutes to complete the melting process. After being allowed to cool slowly to room temperature, the inner layer of the sleeve is obtained after polishing, grinding, washing and drying. 3) The inner sleeve obtained in step 2) is self-locked and assembled with the sleeve body to obtain the environmentally adaptive vehicle wheel hub bolt fastening sleeve.

10. The method for preparing the environmentally adaptive vehicle wheel hub bolt fastening sleeve according to claim 9, in step 1), 42CrMo alloy powder is used as the raw material powder for selective laser powder melting technology, with a particle size range of 15-53μm and a purity of over 95%; the process parameters for selective laser powder melting are: laser power of 280-300W, scanning speed of 0.5-1.5m / s, scanning spacing of 0.05-0.10mm, layer thickness of 0.02-0.06mm, and spot diameter of 40-60μm; In step 2), the working gas for cold spraying is helium, with a working pressure of 3-5 MPa and a working gas temperature of 200-220℃.

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