Corrosion-resistant oil seal and surface treatment process thereof

Abstract

The invention discloses a corrosion-resistant oil seal and a surface treatment process thereof, and relates to the technical field of sealing elements. The invention comprises the following components: an outer corrosion-resistant layer: fluororubber or hydrogenated nitrile rubber, the total content of which is 40-60%; the total content of the polytetrafluoroethylene nano-particles is 10 to 20 percent; the total content of silicon carbide or aluminum oxide micro powder is 5-15%; and a graphene dispersion liquid. Through a multi-protection system of the fluororubber (FKM) and polytetrafluoroethylene (PTFE) nano-particle composite outer layer, the chemical nickel-phosphorus plating (Ni-P) alloy plating layer and the silicon dioxide / titanium dioxide nano-coating, super-strong corrosion resistance is achieved, corrosion medium permeation is blocked by the chemical inertness of PTFE, the Ni-P plating layer forms a passive film in an acid environment to inhibit electrochemical corrosion, and the corrosion resistance is good. The compact structure of the silicon dioxide / titanium dioxide coating further blocks erosion, compared with a traditional oil seal (swelling fracture), the corrosion resistance is remarkably improved, the surface coating can be self-repaired through the silicon dioxide reaction when being slightly scratched, and the service life under the harsh working condition is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of seals, and particularly relates to a corrosion-resistant oil seal and its surface treatment process. Background Art

[0002] With the development of industrial equipment towards high precision, long life, and extreme environment adaptability, the oil seal of the seal is a key component used in mechanical devices to prevent liquid or gas leakage. It is widely used in industrial equipment, automobiles, household appliances, etc. Its core function is to form a reliable sealing interface through the close contact of elastic materials with the shaft or hole, blocking the leakage of media or the intrusion of impurities. As the core sealing component, its corrosion resistance directly affects the reliability and maintenance cost of the equipment.

[0003] Although traditional oil seal materials (such as nitrile rubber, fluororubber, and polyurethane) have certain oil resistance, they are prone to swelling, aging, and embrittlement under chemical media (such as strong acids, strong alkalis, and organic solvents), high temperature (>150 °C) or low temperature (< -40 °C) working conditions, resulting in seal failure. In addition, traditional surface treatment processes (such as dip coating and spraying) have problems such as insufficient coating adhesion and poor resistance to media penetration, and it is difficult to meet the requirements of complex working conditions.

[0004] Therefore, we provide a corrosion-resistant oil seal and its surface treatment process to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a corrosion-resistant oil seal and its surface treatment process. By optimizing the material formula and surface treatment process, the corrosion resistance is significantly improved, and the surface layer coating can self-repair through the siliconization reaction when slightly scratched, extending the service life under harsh working conditions.

[0006] To solve the above technical problems, the present invention is realized through the following technical solutions.

[0007] The present invention is a corrosion-resistant oil seal and its surface treatment process, including the following components: Outer corrosion-resistant layer: Fluororubber or hydrogenated nitrile rubber, with a total content of 40 - 60%; Polytetrafluoroethylene nanoparticles, with a total content of 10 - 20%; Silicon carbide or alumina micropowder, with a total content of 5 - 15%; Graphene dispersion liquid, with a total content of 3 - 8%; Middle reinforcement layer: Aramid fiber fabric or fiberglass cloth, with a total content of 15 - 25%; Epoxy resin impregnating agent, with a total content of 5 - 10%; Inner elastic layer: Silicone rubber or ethylene propylene diene monomer rubber, with a total content of 20 - 30%; Nanometer titanium dioxide, with a total content of 2 - 5%.

[0008] The present invention is further configured such that the outer layer uses fluororubber or hydrogenated nitrile rubber as the matrix. After surface activation by ultrasonic treatment at 30 kHz for 10 minutes, it is compounded with polytetrafluoroethylene nanoparticles (particle size 50 - 150 nm, modified with KH - 550 silane coupling agent, Zeta potential of the dispersion liquid - 35 mV), silicon carbide / aluminum oxide micropowder (D50 particle size 25 μm, dispersed with polyvinyl alcohol), and graphene dispersion liquid (concentration 1 - 5 wt%, stabilized with sodium dodecyl sulfate). It is dispersed by a high - speed shearing machine (3000 rpm) and laminated and formed (at 150 - 180 °C, 8 MPa) to form a corrosion - resistant layer with a thickness of 0.1 - 0.3 mm.

[0009] The present invention is further configured such that the intermediate layer uses aramid fiber fabric (grammage 200 - 300 g / m²) or fiberglass cloth. After being cleaned with acetone, dried at 100 °C, and treated with argon plasma (100 W, 30 seconds), it is impregnated with epoxy resin and hot - pressed and cured at 150 °C for 2 hours, and the interlaminar shear strength reaches 65 N / mm².

[0010] The present invention is further configured such that the inner layer uses silicone rubber or ethylene propylene diene monomer rubber as the matrix, adds nanometer titanium dioxide (particle size 10 - 50 nm) and carbon black, and obtains high elasticity through a peroxide or sulfur vulcanization system (150 - 170 °C). Finally, through gradient hot - pressing (inner layer 150 °C / outer layer 180 °C, pressure 8 MPa) compounding, the interfacial shear strength of 35 N / mm² and the thermal conductivity of 0.5 W / m·K are achieved.

[0011] A surface treatment process for a corrosion - resistant oil seal includes the following steps: a. Sand - blast the oil seal to match the surface cleanliness of St3 level, form a micro - rough structure with Ra 0.8 - 1.2 μm, increase the surface area by 2 - 3 times, and significantly improve the mechanical chimeric ability of the coating; b. Use ultrasonic cleaning with acetone / ethanol (40 kHz, 15 minutes), which can completely remove surface grease and processing residues. The cleaning efficiency reaches over 99.5%. After detection by X - ray photoelectron spectroscopy, the surface carbon element content drops from 12% to 0.5%, avoiding the negative impact of organic substances on the bonding force of the coating; c. Use argon plasma (power 150 W, treat for 8 minutes) to introduce active groups such as - NH2 and - COO⁻ on the surface, and increase the surface energy to 105 mN / m, providing chemical bonding sites for the subsequent coating; d. Bottom spraying: After the blend coating of polyphenylene sulfide and polytetrafluoroethylene is cured at 200 °C, it forms a dense network structure with excellent acid and alkali resistance (mass loss < 0.3% after soaking for 72 hours under the condition of pH 2 - 12). Scanning electron microscopy shows that the coating porosity is less than 1%, and the polytetrafluoroethylene nanoparticles are evenly dispersed (particle size 80 nm), endowing self-lubricating characteristics (friction coefficient reduced to 0.08); e. Middle layer plating: Electroless nickel-phosphorus (Ni-P) alloy (phosphorus content 10%) is deposited in a plating solution with pH 5.0 to obtain an ultrafine structure with a grain size of 20 - 30 nm. The hardness of the plating layer reaches HV800, and the porosity < 0.5%; f. Surface nano-modification: A silica / titania (molar ratio 3:1) nano-film prepared by the sol-gel method forms a sharp interface structure after curing at 150 °C; g. Post-treatment strengthening: A micro-pit array (diameter 50 - 100 μm, depth 10 - 20 μm) is processed on the surface of the oil seal lip using a fiber laser to reduce the friction coefficient; h. Silane coupling agent treatment: KH-550 silane coupling agent is sprayed to enhance the interfacial bonding force between the coating and the rubber matrix; i. Performance test: The oil seal is soaked in 40% sulfuric acid solution for 72 hours, and the mass loss < 0.5%. Under the conditions of a rotational speed of 3000 rpm and a load of 50 N, it runs continuously for 500 hours, and the wear amount of the lip < 0.1 mm. After being placed in an environment of 200 °C for 168 hours, the tensile strength retention rate > 85%.

[0012] The present invention is further configured such that in step a, 180-mesh alumina sand is used for the sandblasting treatment of the oil seal, and the pressure is maintained at 0.2 MPa.

[0013] The present invention is further configured such that in step d, the mass ratio of the blend of polyphenylene sulfide and polytetrafluoroethylene is 7:3; a high-pressure spraying device is used, and the spraying thickness is 50 - 80 μm.

[0014] The present invention is further configured such that the silica / titania composite nano-coating prepared by the sol-gel method in step f is baked at 150 °C for 1 hour after dip coating to form a dense nano-film (thickness 2 - 5 μm).

[0015] The present invention has the following beneficial effects.

[0016] 1. The present invention realizes super strong corrosion resistance through a multi - protection system of a composite outer layer of fluororubber (FKM) and polytetrafluoroethylene (PTFE) nanoparticles, an electroless nickel - phosphorus (Ni - P) alloy coating, and a silica / titania nano - coating. The chemical inertness of PTFE blocks the penetration of corrosive media. The Ni - P coating forms a passivation film in an acidic environment to inhibit electrochemical corrosion. The dense structure of the silica / titania coating further blocks erosion. After being soaked in a 40% sulfuric acid solution for 72 hours, the mass loss is <0.5%, and there are no swelling cracks on the surface. Compared with traditional oil seals (swelling and cracking), the corrosion - resistant performance is significantly improved. When the surface coating is slightly scratched, it can self - repair through a silicification reaction, extending the service life under harsh working conditions.

[0017] 2. In response to the problem of lip wear under high - speed and high - load conditions, the present invention uses silicon carbide micropowder to strengthen the hardness of the outer layer (Hv≥800), and laser micro - texturing on the lip to form a micro - pit array (diameter 50 - 100μm, depth 10 - 20μm). The coefficient of friction is reduced to 0.05 - 0.1 by hydrodynamic lubrication. The intermediate layer of aramid fiber / epoxy resin composite structure improves the tear strength, and the gradient hot - pressing process enhances the interfacial bonding force. After actual measurement, the lip wear is <0.1mm after continuous operation at 3000rpm and 50N load for 500 hours. The service life is better than that of traditional products, effectively reducing the equipment maintenance cost.

[0018] 3. The improved oil seal of the present invention breaks through the temperature range limitation of traditional rubber oil seals. The inner layer of silicone rubber (VMQ) / ethylene propylene diene monomer rubber (EPDM) and the outer layer of polyphenylene sulfide (PPS) coating work together to achieve wide - temperature stability from - 50°C to 250°C. The silica / titania nano - coating has both ultraviolet protection and self - repair functions: the exposed silica in micro - cracks oxidizes under light / heat to form a dense oxide to fill the defects. After being tested by high - temperature aging at 200°C for 168 hours, the tensile strength retention rate is >85%, far exceeding the industry standard, and it is suitable for long - term sealing in extreme environments such as petrochemical pipelines and automobile engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments will be briefly introduced below.

[0020] Figure 1 It is a flow schematic diagram of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The technical solutions in the embodiments of the present invention will be described below with reference to the drawings in the embodiments of the present invention. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0022] Example 1 Please refer to Figure 1, the present invention relates to a corrosion-resistant oil seal and its surface treatment process, including the following components: Outer corrosion-resistant layer: Fluororubber or hydrogenated nitrile rubber, with a total content of 40 - 60%; Polytetrafluoroethylene nanoparticles, with a total content of 10 - 20%; Silicon carbide or alumina micropowder, with a total content of 5 - 15%; Graphene dispersion, with a total content of 3 - 8%; Intermediate reinforcement layer: Aramid fiber fabric or fiberglass cloth, with a total content of 15 - 25%; Epoxy resin impregnating agent, with a total content of 5 - 10%; Inner elastic layer: Silicone rubber or ethylene propylene diene monomer rubber, with a total content of 20 - 30%; Nano titanium dioxide, with a total content of 2 - 5%.

[0023] The outer layer is based on fluororubber or hydrogenated nitrile rubber. After surface activation by ultrasonic treatment at 30 kHz for 10 minutes, it is compounded with polytetrafluoroethylene nanoparticles (particle size 50 - 150 nm, modified with KH - 550 silane coupling agent, dispersion Zeta potential - 35 mV), silicon carbide / alumina micropowder (D50 particle size 25 μm, polyvinyl alcohol dispersant), and graphene dispersion (concentration 1 - 5 wt%, sodium dodecyl sulfate stabilizer), and dispersed and laminated by a high-speed shear machine (3000 rpm) at 150 - 180 °C and 8 MPa to form a 0.1 - 0.3 mm thick corrosion-resistant layer.

[0024] The intermediate layer uses aramid fiber fabric (gram weight 200 - 300 g / m²) or fiberglass cloth. After being cleaned with acetone, dried at 100 °C, and treated with argon plasma (100 W, 30 seconds), it is impregnated with epoxy resin and hot-pressed and cured at 150 °C for 2 hours, and the interlaminar shear strength reaches 65 N / mm².

[0025] The inner layer is based on silicone rubber or ethylene propylene diene monomer rubber, adding nano titanium dioxide (particle size 10 - 50 nm) and carbon black, and high elasticity is obtained through a peroxide or sulfur vulcanization system (150 - 170 °C). Finally, it is compounded by gradient hot pressing (inner layer 150 °C / outer layer 180 °C, pressure 8 MPa) to achieve an interfacial shear strength of 35 N / mm² and a thermal conductivity of 0.5 W / m·K.

[0026] A surface treatment process for a corrosion-resistant oil seal, including the following steps: a. Sandblast the oil seal and, in combination with a surface cleanliness of St3 level, form a micro-rough structure with Ra of 0.8 - 1.2 μm, increasing the surface area by 2 - 3 times and significantly improving the mechanical interlocking ability of the coating. For the sandblasting treatment of the oil seal, use 180-mesh alumina sand and maintain the pressure at 0.2 MPa; b. Use acetone / ethanol ultrasonic cleaning (40 kHz, 15 minutes), which can completely remove surface grease and processing residues. The cleaning efficiency is over 99.5%. After X-ray photoelectron spectroscopy detection, the surface carbon element content drops from 12% to 0.5%, avoiding the negative impact of organic substances on the bonding strength of the coating. The mass ratio of the blend of polyphenylene sulfide and polytetrafluoroethylene is 7:3; Use a high-pressure spraying device with a spraying thickness of 50 - 80 μm; c. Introduce active groups such as -NH2 and -COO⁻ on the surface using argon plasma (power 150 W, treatment for 8 minutes), increasing the surface energy to 105 mN / m and providing chemical bonding sites for the subsequent coating; d. Bottom layer spraying: After curing the blend coating of polyphenylene sulfide and polytetrafluoroethylene at 200 °C, a dense network structure is formed, with excellent acid and alkali resistance (mass loss < 0.3% after soaking in pH 2 - 12 conditions for 72 hours). Scanning electron microscopy shows that the coating porosity is less than 1%, and the polytetrafluoroethylene nanoparticles are evenly dispersed (particle size 80 nm), endowing self-lubricating properties (friction coefficient reduced to 0.08); e. Middle layer plating: Electroless nickel-phosphorus (Ni-P) alloy (phosphorus content 10%) is deposited in a plating solution with pH 5.0 to obtain an ultrafine structure with a grain size of 20 - 30 nm. The hardness of the plating layer reaches HV800, and the porosity < 0.5%; f. Surface layer nano-modification: A silica / titania (molar ratio 3:1) nano-film prepared by the sol-gel method forms a sharp interface structure after curing at 150 °C. After dip-coating with the silica / titania composite nano-coating prepared by the sol-gel method and baking at 150 °C for 1 hour, a dense nano-film is formed (thickness 2 - 5 μm; g. Post-treatment strengthening: Use a fiber laser to process a micro-pit array (diameter 50 - 100 μm, depth 10 - 20 μm) on the surface of the oil seal lip to reduce the friction coefficient; h. Treatment with silane coupling agent: Spray KH-550 silane coupling agent to enhance the interfacial bonding strength between the coating and the rubber matrix; i. Performance testing: Immerse the oil seal in a 40% sulfuric acid solution for 72 hours, with a mass loss < 0.5%. Under the conditions of a rotational speed of 3000 rpm and a load of 50 N, continuously operate for 500 hours, with the lip wear < 0.1 mm. Place it in an environment of 200 °C for 168 hours, and the tensile strength retention rate > 85%.

[0027] Example 2 Please refer to Figure 1, on the basis of Example 1, it includes the following components: Outer corrosion-resistant layer: Fluororubber or hydrogenated nitrile rubber, with a total content of 40 - 60%; Polytetrafluoroethylene nanoparticles, with a total content of 10 - 20%; Silicon carbide or alumina micropowder, with a total content of 5 - 15%; Graphene dispersion, with a total content of 3 - 8%; Intermediate reinforcement layer: Aramid fiber fabric or fiberglass cloth, with a total content of 15 - 25%; Epoxy resin impregnating agent, with a total content of 5 - 10%; Inner elastic layer: Silicone rubber or ethylene propylene diene monomer rubber, with a total content of 20 - 30%; Nanometer titanium dioxide, with a total content of 2 - 5%.

[0028] The outer layer is based on fluororubber or hydrogenated nitrile rubber. After surface activation by ultrasonic treatment at 30 kHz for 10 minutes, it is compounded with polytetrafluoroethylene nanoparticles (particle size 50 - 150 nm, modified with KH - 550 silane coupling agent, Zeta potential of the dispersion - 35 mV), silicon carbide / alumina micropowder (D50 particle size 25 μm, polyvinyl alcohol dispersant), and graphene dispersion (concentration 1 - 5 wt%, sodium dodecyl sulfate stabilizer), and is dispersed and laminated by a high - speed shearing machine (3000 rpm) at 150 - 180 °C and 8 MPa to form a 0.1 - 0.3 mm thick corrosion - resistant layer.

[0029] The intermediate layer uses aramid fiber fabric (grammage 200 - 300 g / m²) or fiberglass cloth. After being cleaned with acetone, dried at 100 °C, and treated with argon plasma (100 W, 30 s), it is impregnated with epoxy resin and hot - pressed and cured at 150 °C for 2 hours, and the interlaminar shear strength reaches 65 N / mm².

[0030] The inner layer is based on silicone rubber or ethylene propylene diene monomer rubber, adding nanometer titanium dioxide (particle size 10 - 50 nm) and carbon black, and obtaining high elasticity through a peroxide or sulfur vulcanization system (150 - 170 °C). Finally, it is compounded by gradient hot - pressing (inner layer 150 °C / outer layer 180 °C, pressure 8 MPa) to achieve an interfacial shear strength of 35 N / mm² and a thermal conductivity of 0.5 W / m·K.

[0031] A surface treatment process for a corrosion - resistant oil seal includes the following steps: a. Sandblast the oil seal, combined with a surface cleanliness of St3 level, to form a micro-rough structure with Ra of 0.8 - 1.2 μm, increasing the surface area by 2 - 3 times, significantly improving the mechanical interlocking ability of the coating. The sandblasting of the oil seal uses 180 - mesh alumina sand, and the pressure is maintained at 0.2 MPa; b. Use acetone / ethanol ultrasonic cleaning (40 kHz, 15 minutes), which can completely remove surface grease and processing residues. The cleaning efficiency reaches over 99.5%. After X-ray photoelectron spectroscopy detection, the surface carbon element content drops from 12% to 0.5%, avoiding the negative impact of organic matter on the bonding strength of the coating. The mass ratio of the blend of polyphenylene sulfide and polytetrafluoroethylene is 7:3; Use a high-pressure spraying device with a spraying thickness of 50 - 80 μm; c. Use argon plasma (power 150 W, treatment for 8 minutes) to introduce active groups such as -NH2 and -COO⁻ on the surface, and the surface energy is increased to 105 mN / m, providing chemical bonding sites for the subsequent coating; d. Bottom layer spraying: After the blend coating of polyphenylene sulfide and polytetrafluoroethylene is cured at 200 °C, a dense network structure is formed, with excellent acid and alkali resistance (mass loss < 0.3% after soaking in pH 2 - 12 conditions for 72 hours). Scanning electron microscopy shows that the coating porosity is less than 1%, and the polytetrafluoroethylene nanoparticles are evenly dispersed (particle size 80 nm), endowing self-lubricating properties (friction coefficient reduced to 0.08); e. Middle layer plating: Electroless nickel-phosphorus (Ni-P) alloy (phosphorus content 10%) is deposited in a plating solution with pH 5.0 to obtain an ultrafine structure with a grain size of 20 - 30 nm. The hardness of the plating layer reaches HV800, and the porosity < 0.5%; f. Surface nano-modification: A silica / titania (molar ratio 3:1) nano-film prepared by the sol-gel method forms a sharp interface structure after curing at 150 °C. The silica / titania composite nano-coating prepared by the sol-gel method is dip-coated and then baked at 150 °C for 1 hour to form a dense nano-film (thickness 2 - 5 μm; g. Post-treatment strengthening: Use a fiber laser to process a micro-pit array (diameter 50 - 100 μm, depth 10 - 20 μm) on the surface of the oil seal lip to reduce the friction coefficient; h. Treatment with silane coupling agent: Spray KH-550 silane coupling agent to enhance the interfacial bonding strength between the coating and the rubber matrix; i. Performance test: Immerse the oil seal in 40% sulfuric acid solution for 72 hours, with a mass loss < 0.5%. Under the conditions of a rotational speed of 3000 rpm and a load of 50 N, continuously operate for 500 hours, and the lip wear amount < 0.1 mm. Place it in an environment of 200 °C for 168 hours, and the tensile strength retention rate > 85%.

[0032] Table 1: Comparison table of technical solution characteristics The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention.

Claims

1. A corrosion-resistant oil seal, characterized in that, It includes the following components: Outer corrosion-resistant layer: Fluororubber or hydrogenated nitrile rubber, with a total content of 40 - 60%; Polytetrafluoroethylene nanoparticles, with a total content of 10 - 20%; Silicon carbide or alumina fine powder, with a total content of 5 - 15%; Graphene dispersion, with a total content of 3 - 8%; Intermediate reinforcing layer: Aramid fiber fabric or fiberglass cloth, with a total content of 15 - 25%; Epoxy resin impregnating agent, with a total content of 5 - 10%; Inner elastic layer: Silicone rubber or ethylene propylene diene monomer rubber, with a total content of 20 - 30%; Nano-titanium dioxide, with a total content of 2 - 5%.

2. The corrosion-resistant oil seal according to claim 1, characterized in that: The outer layer uses fluororubber or hydrogenated nitrile rubber as the matrix. After surface activation by ultrasonic treatment at 30 kHz for 10 minutes, it is compounded with polytetrafluoroethylene nanoparticles (particle size 50 - 150 nm, modified with KH-550 silane coupling agent, dispersion Zeta potential -35 mV), silicon carbide / alumina fine powder (D50 particle size 25 μm, polyvinyl alcohol dispersant), and graphene dispersion (concentration 1 - 5 wt%, sodium dodecyl sulfate stabilizer), and is dispersed and laminated by a high-speed shearing machine (3000 rpm) (150 - 180 °C, 8 MPa) to form a corrosion-resistant layer with a thickness of 0.1 - 0.3 mm.

3. A corrosion-resistant oil seal according to claim 1, characterized in that: The intermediate layer uses aramid fiber fabric (gram weight 200 - 300 g / m²) or fiberglass cloth. After being cleaned with acetone, dried at 100 °C, and treated with argon plasma (100 W, 30 seconds), it is impregnated with epoxy resin and hot-pressed and cured at 150 °C for 2 hours, and the interlaminar shear strength reaches 65 N / mm².

4. The corrosion-resistant oil seal according to claim 1, wherein: The inner layer uses silicone rubber or ethylene propylene diene monomer rubber as the matrix, adds nano-titanium dioxide (particle size 10 - 50 nm) and carbon black, and obtains high elasticity through a peroxide or sulfur vulcanization system (150 - 170 °C). Finally, it is compounded by gradient hot pressing (inner layer 150 °C / outer layer 180 °C, pressure 8 MPa) to achieve an interfacial shear strength of 35 N / mm² and a thermal conductivity of 0.5 W / m·K.

5. A surface treatment process for a corrosion-resistant oil seal, characterized in that, It includes the following steps: a. Sandblast the oil seal to match the surface cleanliness of St3 level, forming a micro-rough structure with Ra 0.8 - 1.2 μm, increasing the surface area by 2 - 3 times, and significantly improving the mechanical chimeric ability of the coating; b. Use acetone / ethanol ultrasonic cleaning (40 kHz, 15 minutes), which can completely remove surface grease and processing residues, with a cleaning efficiency of over 99.5%. After X-ray photoelectron spectroscopy detection, the surface carbon element content drops from 12% to 0.5%, avoiding the negative impact of organic substances on the bonding strength of the coating; c. Use argon plasma (power 150 W, treatment for 8 minutes) to introduce active groups such as -NH2 and -COO⁻ on the surface, and raise the surface energy to 105 mN / m, providing chemical bonding sites for the subsequent coating; d. Bottom spraying: After the blend coating of polyphenylene sulfide and polytetrafluoroethylene is cured at 200 °C, a dense network structure is formed, with excellent acid and alkali resistance (mass loss < 0.3% after soaking for 72 hours under the condition of pH 2 - 12). Scanning electron microscopy shows that the porosity of the coating is less than 1%, and the polytetrafluoroethylene nanoparticles are evenly dispersed (particle size 80 nm), endowing self-lubricating properties (friction coefficient reduced to 0.08); e. Middle layer plating: Electroless nickel-phosphorus (Ni-P) alloy (phosphorus content 10%) is deposited in a plating solution with pH 5.0 to obtain an ultrafine structure with a grain size of 20 - 30 nm. The hardness of the plating layer reaches HV800, and the porosity < 0.5%; f. Surface nano modification: A silica / titania (molar ratio 3:1) nano film prepared by the sol-gel method forms a sharp interface structure after curing at 150 °C; g. Post-treatment strengthening: A micro-pit array (diameter 50 - 100 μm, depth 10 - 20 μm) is processed on the surface of the oil seal lip using a fiber laser to reduce the friction coefficient; h. Silane coupling agent treatment: KH-550 silane coupling agent is sprayed to enhance the interfacial bonding force between the coating and the rubber matrix; i. Performance test: The oil seal is soaked in 40% sulfuric acid solution for 72 hours, with a mass loss < 0.5%. Under the conditions of a rotational speed of 3000 rpm and a load of 50 N, it runs continuously for 500 hours, and the wear amount of the lip is < 0.1 mm. After being placed in an environment of 200 °C for 168 hours, the tensile strength retention rate > 85%.

6. The surface treatment process of a corrosion-resistant oil seal according to claim 5, characterized in that: In step a, the alumina sand with 180 meshes is used for the sandblasting treatment of the oil seal, and the pressure is maintained at 0.2 MPa.

7. The surface treatment process of a corrosion-resistant oil seal according to claim 5, characterized in that: In step d, the mass ratio of the blend of polyphenylene sulfide and polytetrafluoroethylene is 7:3; a high-pressure spraying device is used, and the spraying thickness is 50 - 80 μm.

8. The surface treatment process of a corrosion-resistant oil seal according to claim 5, characterized in that: In step f, the silica / titania composite nano coating prepared by the sol-gel method is baked at 150 °C for 1 hour after dip coating to form a dense nano film (thickness 2 - 5 μm).

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