Surface preparation method for plasma sprayed self-lubricating functional film layer of aluminum alloy wheel

Abstract

This invention discloses a surface treatment method for a self-lubricating functional film layer on aluminum alloy wheels using plasma spraying. The method includes preparing a mixed powder composed of Ni60, Al2O3, and TiN, ball milling and uniformly mixing them according to the specified ratio, and then using plasma spraying technology to prepare a wear-resistant alloy coating on a substrate. Subsequently, a composite emulsion is prepared using FR301 grade PTFE emulsion, MoS₂ micro powder, and a dispersant, and the aluminum alloy wheel is impregnated and dried. The same PTFE-MoS₂ emulsion is then sprayed using an air spraying method. After spraying, the wheel is dried and cooled. This invention applies plasma spraying technology to the corrosion resistance treatment of aluminum alloy wheel surfaces and combines it with self-lubricating film layer technology, achieving a dual improvement in corrosion resistance and wear resistance. By preparing a composite film layer with high hardness, high corrosion resistance, and low friction coefficient, the service life and driving safety of aluminum alloy wheels are significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of materials surface engineering technology, specifically relating to a surface treatment process that improves the corrosion resistance and wear resistance of aluminum alloy wheels by combining plasma spraying with a self-lubricating functional film. Background Technology

[0002] Underground pipeline logistics transportation systems, as an innovative approach to alleviating urban logistics and traffic problems, have attracted close attention both domestically and internationally. In recent years, many regions in my country have begun to deploy underground logistics transportation systems.

[0003] The transport vehicles used in underground pipeline logistics transportation systems are mainly AGVs or driverless vehicles. The wheels of these vehicles need to be adapted to the complex working conditions of underground logistics transportation, and potential materials include steel wheels, aluminum alloy wheels, magnesium alloy wheels, and carbon fiber wheels.

[0004] In the automotive parts industry, aluminum alloy wheels are widely used due to their lightweight, high strength, and good machinability. However, in practical applications, especially under harsh environmental conditions such as humidity and salt spray, aluminum alloy wheels face serious corrosion problems, mainly manifested as pitting corrosion and intergranular corrosion. These corrosion phenomena not only affect the aesthetics of the wheels, but more importantly, they weaken the structural strength of the wheels, thereby threatening driving safety.

[0005] Furthermore, traditional processes used to improve the surface properties of aluminum alloy wheels, such as electroplating and anodizing, while enhancing corrosion resistance to some extent, generally suffer from low hardness and poor self-lubricating properties. This leads to increased friction and wear between the wheel and the braking system during braking, shortening wheel lifespan and increasing energy consumption and noise. The industry has attempted to address these issues through various technological means, but many limitations remain. Micro-arc oxidation combined with sealant treatment has effectively improved the corrosion resistance of aluminum alloy wheels. However, this approach has not made significant progress in optimizing the coefficient of friction, still facing the problem of increased friction and wear during braking. Existing technologies include applying WC-Co (tungsten carbide-cobalt) coatings via thermal spraying, a coating renowned for its excellent wear resistance. However, its high cost limits its widespread application; simultaneously, the preparation and use of WC-Co coatings may have adverse environmental impacts, such as the emission of harmful substances, thus affecting its environmental compatibility.

[0006] In summary, while existing technologies have alleviated the corrosion and friction wear problems of aluminum alloy wheels to some extent, they all have their own limitations and shortcomings. Therefore, there is an urgent need to develop a new, efficient, economical, and environmentally friendly coating technology to fully meet the needs of aluminum alloy wheels in terms of corrosion prevention and friction reduction. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention discloses a surface treatment process for improving the corrosion resistance and wear resistance of aluminum alloy wheels through plasma spraying combined with a self-lubricating functional film. This wear-resistant alloy coating is prepared on the surface of a 7075 aluminum alloy substrate. The raw material composition is: 10-30 wt.% Al2O3 powder; 5-20 wt.% TiN powder; and the balance Ti60 powder. It is prepared using plasma spraying technology. Subsequently, a coating process involving precise heat treatment and physicochemical treatment allows the PTFE and oxide film to bond together, forming an extremely strong and inseparable composite film that is both hard and lubricating.

[0008] The complete technical solution of this invention includes:

[0009] A method for preparing a self-lubricating functional film layer for plasma spraying on aluminum alloy wheels includes the following steps:

[0010] Step 1: Plasma Spraying

[0011] Prepare a mixed powder consisting of Ni60, Al2O3 and TiN. After ball milling and mixing the Ni60 powder, Al2O3 powder and TiN powder according to the ratio, the powder is vacuum dried to obtain the coating powder and loaded into the powder feeder.

[0012] After surface pretreatment and preheating, a wear-resistant alloy coating is prepared on the substrate using plasma spraying technology; the main gas used in the plasma spraying process is argon, and the auxiliary gas used is hydrogen.

[0013] Step 2: Preparation and hot dipping treatment of FR301PTFE-MoS2 composite emulsion

[0014] Using FR 301 A composite emulsion is obtained by ultrasonically dispersing PTFE emulsion, MoS2 micro powder and dispersant of a certain grade. The aluminum alloy wheel that has been plasma sprayed is immersed in the composite emulsion. After constant temperature impregnation, it is lifted at a certain speed and then dried after draining off the excess emulsion.

[0015] Step 3: Polymer spraying and co-modification treatment

[0016] Using the air spraying method, the spray gun pressure and spray gun distance were adjusted to spray the same component PTFE-MoS2 emulsion in a cross pattern at a certain speed. After spraying, the emulsion was allowed to stand at room temperature to level. Then, the wheel was placed in an oven and heated to the curing temperature at a certain rate and kept at that temperature. The wheel was then cooled to room temperature with the oven to obtain a plasma-sprayed self-lubricating functional film layer for aluminum alloy wheels.

[0017] Furthermore, in step 1, the particle size of TiN powder and Ni60 powder in the mixed powder is 270-350 mesh, and the particle size of Al2O3 powder is 180-220 mesh.

[0018] Further, the mixing process in step 1 is as follows: Al2O3 powder, TiN powder and Ni60 powder are placed in a ball mill and ground at a speed of 60 rpm for 30 hours to make the mixture uniform. During the high-speed grinding process in the ball mill, two types of Cr15 balls with diameters of 12.6 mm and 6 mm are used, with a weight ratio of 1:1 between the two types of balls.

[0019] Furthermore, in step 1, before plasma spraying, the surface of the 7075 aluminum alloy wheel is sandblasted with 20-70 mesh corundum sand to remove the surface oxide film and increase the surface roughness of the substrate.

[0020] Furthermore, the plasma spraying process parameters are: current 670A, voltage 48V, argon flow rate 48L / min, hydrogen flow rate 12L / min, spraying distance 110mm, and powder feeding speed 30g / min.

[0021] Take FR301PTFE emulsion, add MoS2 micro powder with a particle size of 1-10μm and an appropriate amount of polyethylene glycol dispersant, and use 200-300W ultrasonic mixing and stirring to disperse to obtain a composite emulsion.

[0022] Furthermore, based on the increase in the coefficient of friction within the range of 200-400℃, the parameter values ​​in steps 2 and 3 are designed.

[0023] Furthermore, the parameters include MoS2 content, PTFE solid content, impregnation temperature, and curing temperature.

[0024] First, the optimized ranges for each parameter value were obtained: the proportion of MoS2 micro powder in the total mass of the emulsion was 5%-20%; the solid content of PTFE was 20%-30%; the impregnation temperature was 80-120℃; the impregnation time was 30 minutes; the curing temperature was 200-260℃; and the heat preservation time was 2.5 hours.

[0025] Subsequently, a quantitative relationship between the increase in friction coefficient and the aforementioned parameters was established. Based on the viscosity requirements of the emulsion during the impregnation process, the emulsion viscosity within the impregnation temperature range was calibrated, determining the impregnation temperature to be 100-110℃ and the PTFE emulsion solid content to be 25%-28%. Considering the relationship between curing temperature and the generation of crosslinking and lubrication layer cracks, the curing temperature was determined to be 230-240℃. Based on the friction coefficient increase requirements of the self-lubricating layer and the quantitative relationship between the friction coefficient increase and the aforementioned parameters, the MoS2 content was determined to be 10%-15% of the total emulsion mass.

[0026] Furthermore, the aluminum alloy wheel is a 7075 aluminum alloy wheel.

[0027] Furthermore, the aluminum alloy wheel surface obtained by the method is a plasma-sprayed self-lubricating functional film layer, the film layer comprising a plasma-sprayed wear-resistant alloy ceramic coating, a self-lubricating underlayer, and a self-lubricating surface layer.

[0028] Furthermore, the aluminum alloy wheel is equipped with the aforementioned plasma-sprayed self-lubricating functional film layer.

[0029] The beneficial effects of this invention compared to the prior art are as follows:

[0030] 1. This invention applies plasma spraying technology to the corrosion resistance treatment of aluminum alloy wheel surfaces, and combines it with self-lubricating film technology to achieve a dual improvement in corrosion resistance and wear resistance. By designing spraying parameters and selecting film materials, this invention successfully prepares a composite film with high hardness, high corrosion resistance, and a low coefficient of friction. The film performance is optimized, significantly improving the service life and driving safety of aluminum alloy wheels. The plasma spraying technology and self-lubricating film preparation process used in this invention are both green and environmentally friendly processes, conforming to the current trend of energy conservation and emission reduction.

[0031] 2. Hot-dip density optimization creates a dense-porous gradient structure in the lubricant layer. The dense surface layer slows down lubricant loss, while the porous inner layer stores lubricant, which is slowly released through micro-wear during friction, significantly improving lifespan.

[0032] 3. By quantifying the relationship between the increase in friction coefficient and core parameters, multi-parameter coordinated control of the hot infiltration and curing processes is achieved, preventing coating cracking while improving the bonding strength with the substrate, ensuring that the lubricating film does not detach under variable load conditions, and reducing wear rate under impact loads. Wide temperature range lubrication from room temperature to 400℃.

[0033] 4. In terms of overall performance, the coating of this invention exhibits significant advantages: its hardness can reach over 750 HV, more than 10 times higher than that of aluminum alloy substrates; its coefficient of friction is stable at around 0.15, far lower than the 0.35 of traditional self-lubricating coatings, and its wear rate is less than 0.5 × 10⁻⁻⁻⁶. 7 The wear resistance is improved by more than 30% (mm³ / N·m); the multi-layer composite structure and heat treatment process achieve an interfacial bonding strength of 14MPa between the substrate and the film layer. Simultaneously, through the synergistic effect of the plasma-sprayed dense structure and self-lubricating components, this coating maintains excellent corrosion resistance and tribological stability under varying environments such as salt spray and humidity, achieving a leap from "single protection" to "corrosion-wear synergistic protection". Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly introduced below. The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings. The accompanying drawings are schematic and should not be construed as limiting the present invention in any way. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a diagram of the interface structure of the self-lubricating functional film layer coated by plasma spraying according to the present invention. Detailed Implementation

[0036] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0037] This invention discloses a surface treatment method for a self-lubricating functional film layer of aluminum alloy wheels by plasma spraying, comprising the following steps:

[0038] Step 1: Plasma Spraying

[0039] 1) Raw material preparation: Using 7075 aluminum alloy wheels as the base, the coating powder is a mixture of Ni60, Al2O3, and TiN powders. The particle size of TiN and Ni60 powders is 270-350 mesh, and the particle size of Al2O3 powder is 180-220 mesh. The raw materials Ni60 powder, Al2O3 powder, and TiN powder are mixed evenly in each proportion. The mixing process is as follows: Al2O3 powder, TiN powder, and Ni60 powder are placed in a ball mill and ground at 60 rpm for 30 hours to ensure uniform mixing. During the high-speed grinding process in the ball mill, two specifications of Cr15 balls with diameters of 12.6 mm and 6 mm are used, with a weight ratio of 1:1 between the two specifications of balls. The resulting coating powder is placed in a vacuum drying oven and dried at 100℃ for 12 hours, and then loaded into a powder feeder.

[0040] 2) Surface pretreatment: The surface of the 7075 aluminum alloy wheel is sandblasted with 20-70 mesh corundum sand to remove the surface oxide film and increase the surface roughness of the substrate.

[0041] 3) Plasma spraying: After the substrate is preheated to 120°C, a wear-resistant alloy coating is prepared on the substrate using plasma spraying technology. The process parameters for plasma spraying are as follows: the main spraying gas is argon, the auxiliary spraying gas is hydrogen, the current is 670A, the voltage is 48V, the main gas (argon) flow rate is 48L / min, the auxiliary gas (hydrogen) flow rate is 12L / min, the spraying distance is 110mm, and the powder feeding speed is 30g / min.

[0042] Step 2: For FR 301 Preparation and hot dipping treatment of PTFE-MoS2 composite emulsion

[0043] 1) Preparation of composite emulsion: Take a certain solid content as FR 301 A composite emulsion is obtained by adding MoS2 micro powder to a PTFE emulsion, then adding an appropriate amount of polyethylene glycol dispersant, followed by ultrasonic dispersion and high-speed stirring.

[0044] 2) Hot-dip process: The composite emulsion is preheated to a certain temperature. The wheel is vertically immersed in the emulsion, and the process is carried out at a constant temperature and then lifted at a uniform speed. Excess emulsion is then allowed to drain. This process, combining constant-temperature hot-dip with uniform-speed lifting, prevents defects such as sagging and streaks in the coating. The emulsion forms a three-dimensional lubricating structure, improving the durability of the lubricating layer. During the hot-dip process, the viscosity of the composite emulsion decreases after heating. Through capillary adsorption and thermal convection, MoS2 micropowder adheres to the surface along with the emulsion, constructing the underlying lubricating base.

[0045] Step 3: Polymer spraying and co-modification treatment

[0046] Pre-drying: Place the heat-dipped wheels in an oven to dry, removing moisture and solvents from the emulsion. Use air spraying, adjusting the spray gun pressure and distance, and spray the above-mentioned FR coating at a certain speed in a cross-hatching pattern. 301 The PTFE-MoS2 emulsion composite and cross-spraying ensure uniform coating thickness and precisely control the dry film thickness to a certain level.

[0047] After spraying, the coating is allowed to level at room temperature. The wheels are placed in an oven, heated to a certain temperature, and then held at that temperature before being cooled to room temperature with the oven. The sprayed polymer is fully compatible with the hot-dip underlayer components, forming a continuous, interface-free lubricating film. During high-temperature curing, PTFE molecules undergo a cross-linking reaction, forming a more robust bond. Simultaneously, the ultra-low friction properties of PTFE and the interlayer slip effect of MoS2 create synergistic lubrication, significantly reducing frictional resistance. Synergistic modification achieves fusion between the underlayer and the surface layer, improving coating adhesion and tensile bond strength. The cured coating combines flexibility and wear resistance, making it suitable for complex working conditions.

[0048] In this process, considering the application scenarios of wheels, it is necessary to meet certain requirements for the increase in friction coefficient within the range of 200-400℃ for harsh environments such as high temperature and variable load, so as to solve the performance shortcomings of traditional coatings that perform well at room temperature but deteriorate rapidly at high temperature, and adapt to the application scenario requirements.

[0049] Therefore, this invention obtains different schemes by combining various parameters with multiple values, and tests the performance of each scheme. During this process, analysis is performed to identify parameters that significantly affect the increase in the friction coefficient at high and low temperatures, specifically including the MoS2 content, PTFE solid content, impregnation temperature, and curing temperature. Based on the analysis results, corresponding parameters are selected and optimized.

[0050] First, we need to obtain the optimization range of each parameter value. The specific analysis results are as follows.

[0051] MoS2 content: PTFE softens and decomposes with increasing temperature, and the decomposition rate accelerates significantly at higher temperatures, leading to a sharp decline in lubrication performance. MoS2's layered structure exhibits excellent solid lubrication properties, but it slowly oxidizes to MoO3 in high-temperature air, still retaining some lubricity. Analysis of test results shows that when the MoS2 content is low, the lubrication layer is dominated by PTFE. Within the 200-400℃ range, PTFE softens and decomposes, leading to lubrication failure and a significant increase in the friction coefficient. However, when the MoS2 content is appropriate, the layered slip of MoS2 and the adhesive lubrication of PTFE create a synergistic effect. At high temperatures, MoS2 can fill the pores left by PTFE decomposition, inhibiting the increase in the friction coefficient. When the MoS2 content is too high, MoS2 powder tends to agglomerate, leading to decreased emulsion dispersibility, increased internal defects in the lubrication layer, and stress concentration at these defects at high temperatures, resulting in a higher friction coefficient increase.

[0052] Meanwhile, MoS2 is an inorganic rigid particle, and PTFE is an organic flexible matrix. Their composite system exhibits a synergistic effect of rigid support and flexible buffering. When the proportion of MoS2 is appropriate, the particles are uniformly distributed within the PTFE matrix, effectively dispersing impact loads and reducing brittle fracture of the lubricating film. However, if the proportion is too high, the agglomerated MoS2 becomes a stress concentration source, easily triggering crack propagation under impact and significantly increasing the fracture rate. If the proportion is too low, the PTFE matrix lacks sufficient toughness, making it prone to plastic deformation fracture under impact. Based on the above analysis and experimental results, the proportion of MoS2 micropowder in the total mass of the emulsion is finally limited to 5%-20%.

[0053] Solid content of PTFE: The solid content determines the density and porosity of the lubricating layer. When the solid content is low, the emulsion viscosity is low, resulting in high porosity in the lubricating layer after dip-coating and spraying. At high temperatures, air easily penetrates the coating, accelerating PTFE oxidation and MoS2 failure, leading to a significant increase in the friction coefficient. Conversely, when the solid content is too high, the emulsion viscosity is too high, dispersibility decreases, and microcracks easily form inside the coating. Under impact, crack propagation leads to an increased fracture rate. Based on the above analysis and experimental results, the solid content of PTFE was ultimately limited to 20%-30%. Within this range, the emulsion viscosity is moderate, and the film density is high, ensuring both oxidation resistance at high temperatures and improved structural stability under impact loads.

[0054] Impregnation temperature and time: Impregnation temperature affects the penetration depth of the emulsion in the pores of the plasma-sprayed coating. Since the surface of the plasma-sprayed coating contains numerous micron-sized pores, the core of dip coating is to allow the composite emulsion to penetrate these pores, forming a double-layer structure of pore filling and surface film formation, thus improving interfacial adhesion. If the impregnation temperature is too low, the emulsion viscosity is high, making it difficult to penetrate the pores and resulting in surface film formation only. At high temperatures, this surface film is prone to detachment, leading to a significant increase in the coefficient of friction. Impregnation time is positively correlated with penetration depth, but when the time exceeds 30 minutes, the penetration depth tends to saturate, and further extending the time does not significantly improve performance. Based on the above analysis and experimental results, a temperature of 80-120℃ was finally selected to achieve a moderate emulsion viscosity and a penetration depth exceeding 80% of the coating pores. The filled pores can suppress stress relaxation at high temperatures and improve interfacial adhesion strength. The impregnation time was 30 minutes.

[0055] Curing temperature: Curing temperature is a key parameter for the crosslinking of the PTFE matrix. Insufficient temperature results in incomplete melting of PTFE, low crosslinking degree, and weak coating adhesion. Excessive temperature leads to thermal degradation of PTFE, generating low molecular weight products, and the decomposition rate accelerates at high temperatures. Regarding the relationship between holding time and crosslinking degree, the crosslinking degree tends to saturate after 2.5 hours of holding time. Further extending the holding time will not increase the crosslinking degree but will instead lead to excessive degradation of PTFE, reducing its high-temperature performance. Based on the above analysis and experimental results, the final curing temperature was set at 200-260℃. After PTFE melts, a continuous phase is formed, with MoS2 particles uniformly embedded within it, and the crosslinking degree essentially reaches saturation.

[0056] Subsequently, a relevant model was established based on the experimental results, and the parameters were optimized based on the model:

[0057] Establish a model for defining the increase in friction coefficient

[0058]

[0059] in, The coefficient of friction at 200℃ The coefficient of friction is 400℃.

[0060] Through multiple linear regression analysis, the quantitative relationship with the core parameters is established as follows:

[0061]

[0062] in, The percentage of MoS2. The solid content of the PTFE emulsion is (%). The curing temperature is ℃. This is a constant term, the value of which is determined by fitting the experimental results.

[0063] Based on the viscosity requirements of the emulsion during the impregnation process (related to the pore depth of the plasma spray coating, the optimal impregnation viscosity was determined to be 500~600 mPa·s), and viscosity is related to solid content and temperature. The emulsion viscosity within the impregnation temperature range was calibrated, and the appropriate impregnation temperature was determined to be 100-110℃, with a PTFE emulsion solid content of 25%-28%.

[0064] Based on the relationship between curing temperature and the tendency for crack formation in the lubricating layer (within a limited range, curing temperature increases the degree of crosslinking, but due to the difference in thermal expansion coefficients compared to plasma-sprayed coatings, it also leads to an increased tendency for crack formation), a curing temperature of 230-240℃ is determined to be preferable. Based on this range, and considering the required increase in the friction coefficient of the self-lubricating layer (≤20%), and according to the quantitative relationship between the friction coefficient and core parameters, the MoS2 content is determined to be 10%-15% of the total emulsion mass.

[0065] In the above process, the selected MoS2 micro powder has a particle size of 1-10μm. After adding polyethylene glycol dispersant, it is ultrasonically dispersed at 200-300W for 30min, and then mixed at high speed of 1200r / min to ensure uniform dispersion of MoS2.

[0066] During the impregnation process, the wheel is vertically immersed in the emulsion. After impregnation, it is lifted at a uniform speed of 5-10 mm / min and allowed to stand at room temperature for 15 minutes to drain excess emulsion. The hot-impregnated wheel is then placed in an oven at 120-150℃ and dried for 1-2 hours to remove moisture and solvent from the emulsion before spraying. The spray gun pressure is 0.3-0.5 MPa, the spray gun distance is 15-25 cm, and the FR coating is applied in a cross-hatching pattern at a speed of 10-15 cm / s. 301 PTFE-MoS2 emulsion. After spraying, allow to stand at room temperature for 25 minutes to level. Place the wheel in an oven and heat to the curing temperature at a rate of 5-8℃ / min. After the curing period, cool to room temperature with the oven at a rate ≤10℃ / min. The resulting self-lubricating layer achieves precise matching between the low-temperature, low-friction properties of PTFE and the high-temperature stability of MoS2 through process parameters. The self-lubricating layer has a density ≥92%, and the lubricating film rupture rate is less than 5% under a 400℃ impact load. The efficiency of the two-phase synergy is improved. The particle size and dispersion of MoS2 allow it to be uniformly embedded in the PTFE matrix to form micro-lubricating units. PTFE provides a low-friction interface at room temperature, while MoS2 maintains the integrity of the lubricating film at high temperatures. The self-lubricating layer combines flexibility and wear resistance, making it suitable for complex working conditions. It achieves lubrication over a wide temperature range of room temperature to 400℃.

[0067] The final obtained plasma-sprayed self-lubricating functional film structure is as follows: Figure 1As shown, the plasma-sprayed coating has a layered stacked structure. The Ni60 alloy matrix is ​​a continuous phase, with Al2O3 particles and TiN particles dispersed in the Ni60 layers. The FR301 PTFE-MoS2 lubricating layer is relatively flat with visible fine wrinkles. The MoS2 is in the form of small flakes or particles, evenly distributed in the PTFE matrix, and the overall dispersion is relatively uniform. The lubricating layer is tightly bonded to the sprayed underlayer, and the PTFE penetrates into the surface pores to form a mechanical interlock, with no peeling at the interface.

[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a self-lubricating functional film layer on the surface of an aluminum alloy wheel by plasma spraying, characterized in that, Includes the following steps: Step 1: Plasma Spraying Prepare a mixed powder consisting of Ni60, Al2O3 and TiN. After ball milling and mixing the Ni60 powder, Al2O3 powder and TiN powder according to the ratio, the powder is vacuum dried to obtain the coating powder and loaded into the powder feeder. After surface pretreatment and preheating, a wear-resistant alloy coating is prepared on the substrate using plasma spraying technology; the main gas used in the plasma spraying process is argon, and the auxiliary gas used is hydrogen. Step 2: FR 301 Preparation of PTFE-MoS2 composite emulsion and hot dipping treatment FR 301 PTFE emulsion of FR-4 brand, MoS2 micro-powder and dispersant, composite emulsion was obtained by ultrasonic dispersion, the aluminum alloy wheel finished by plasma spraying was immersed in the composite emulsion, after constant temperature infiltration, it was pulled up at a certain speed, the excess emulsion was drained, and then it was dried. Step 3: Polymer spraying and co-modification treatment Using the air spraying method, the spray gun pressure and spray gun distance were adjusted to spray the same component PTFE-MoS2 emulsion in a cross pattern at a certain speed. After spraying, the emulsion was allowed to stand at room temperature to level. Then, the wheel was placed in an oven and heated to the curing temperature at a certain rate and kept at that temperature. The wheel was then cooled to room temperature with the oven to obtain a plasma-sprayed self-lubricating functional film layer for aluminum alloy wheels.

2. The method for preparing a self-lubricating functional film layer for plasma spraying on aluminum alloy wheels according to claim 1, characterized in that, In step 1, the particle size of TiN powder and Ni60 powder in the mixed powder is 270-350 mesh, and the particle size of Al2O3 powder is 180-220 mesh.

3. The method for preparing a self-lubricating functional film layer for plasma spraying on aluminum alloy wheels according to claim 2, characterized in that, Step 1 is the mixing process: Al2O3 powder, TiN powder and Ni60 powder are placed in a ball mill and ground at 60 rpm for 30 hours to make them uniformly mixed. During the high-speed grinding process in the ball mill, two types of Cr15 balls with diameters of 12.6 mm and 6 mm are used, with a weight ratio of 1:1 between the two types of balls.

4. The method for preparing a self-lubricating functional film layer for plasma spraying on aluminum alloy wheels according to claim 3, characterized in that, In step 1, before plasma spraying, the surface of the 7075 aluminum alloy wheel is sandblasted with 20-70 mesh corundum sand to remove the surface oxide film and increase the surface roughness of the substrate.

5. The method for preparing a self-lubricating functional film layer for plasma spraying on aluminum alloy wheels according to claim 4, characterized in that, The parameters for the plasma spraying process are: current 670A, voltage 48V, argon flow rate 48L / min, hydrogen flow rate 12L / min, spraying distance 110mm, and powder feeding speed 30g / min.

6. The method for preparing a self-lubricating functional film layer for plasma spraying on aluminum alloy wheels according to claim 1, characterized in that, Based on the increase in friction coefficient within the range of 200-400℃, design the parameter values ​​in steps 2 and 3.

7. The method for preparing a self-lubricating functional film layer for plasma spraying on aluminum alloy wheels according to claim 6, characterized in that, In step 2, take FR301PTFE emulsion, add MoS2 micro powder with a particle size of 1-10μm and an appropriate amount of polyethylene glycol dispersant, and use 200-300W ultrasonic mixing and stirring to disperse to obtain a composite emulsion.

8. The method for preparing a self-lubricating functional film layer for plasma spraying on aluminum alloy wheels according to claim 7, characterized in that, The aluminum alloy wheels mentioned are 7075 aluminum alloy wheels.

9. A self-lubricating functional film layer for plasma spraying on the surface of an aluminum alloy wheel obtained by the method of any one of claims 1-8, characterized in that, The film layer includes a plasma-sprayed wear-resistant alloy ceramic coating, a self-lubricating underlayer, and a self-lubricating surface layer.

10. An aluminum alloy wheel with the plasma-sprayed self-lubricating functional film layer as described in claim 9.

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