High-performance scratch-resistant wear-resistant corrosion-resistant nylon material replacing steel with plastic

Abstract

The invention relates to the field of nylon materials, provides a high-performance, scratch-resistant, wear-resistant and corrosion-resistant nylon material replacing steel with plastic, and solves the problem that an existing nylon material is insufficient in scratch resistance, wear resistance and corrosion resistance. The material is prepared from a surface modified calcium fluoride and aluminum oxide whisker filler, polytetrafluoroethylene coated boron nitride particles, nylon matrix resin, a compatilizer, an antioxidant and a lubricant. The dispersibility and the interface compatibility of the key components are improved by adopting a special preparation process, so that the mechanical property, the wear resistance and the chemical stability of the composite material are remarkably enhanced. The material is suitable for metal replacement application in the fields of automobiles, machinery and the like, realizes excellent scratch resistance and wear resistance, solves the problem of poor corrosion resistance of nylon materials, and has wide application value.

Description

Technical Field

[0001] The present invention relates to the field of nylon materials, and particularly to a high-performance scratch-resistant, wear-resistant and corrosion-resistant steel-substituted nylon material with plastics. Background Art

[0002] In high-intensity operating environments such as automobile manufacturing, rail transit, and construction machinery, metal components are widely used in core parts such as load-bearing, friction, and connection. However, the problems of their large weight, high processing cost, and easy corrosion are becoming increasingly prominent. Replacing steel with plastics, especially replacing traditional metal materials with nylon materials, has become an important development direction under the trend of lightweight and functional integration. When applied to key components such as gears, bearings, and structural brackets, the material not only needs to have excellent mechanical strength but also must maintain stable scratch-resistant, wear-resistant, and corrosion-resistant properties under long-term friction, impact, and complex chemical media. Under extreme working conditions such as high humidity, high salt, and high temperature, the surface damage resistance and chemical stability of the material directly affect the service life and safety of the product. Therefore, developing nylon composite materials with high-performance scratch resistance, wear resistance, and corrosion resistance is of great significance for improving the operation reliability of equipment, extending the maintenance cycle, and reducing the overall operation cost. At the same time, the wide application of such materials can further promote the development of the lightweight engineering material system, expand the application boundary of steel substitution with plastics, and help the industrial manufacturing to transform towards high efficiency, greenness, and intelligence.

[0003] Currently, although engineering plastics based on nylon have initially achieved the goal of replacing steel with plastics in many industrial fields due to their good processability and mechanical properties, the existing materials still have significant deficiencies in dealing with high-intensity friction and complex corrosion environments, which limits their further application in key components. For example, the Chinese patent with the publication number CN117844235B discloses a high-wear-resistant nylon material. Although the addition of fillers improves some mechanical properties of the material, there is still no effective breakthrough in the comprehensive performance of scratch resistance, wear resistance, and corrosion resistance. Especially in high-frequency friction or acid-base corrosion environments, surface wear or performance attenuation is likely to occur. The main reason for this problem is that traditional reinforcement methods are mostly limited to single inorganic fillers, with insufficient interfacial compatibility and microstructural regulation, making it difficult to simultaneously achieve the coordinated improvement of wear resistance and corrosion resistance. In addition, most existing technologies also have obvious shortcomings in filler dispersion, surface modification effectiveness, and composite system stability, resulting in significant performance attenuation of the material during long-term service. Therefore, there is an urgent need to develop a new type of nylon composite material with a reasonable structure design and significant component synergistic reinforcement effect to comprehensively improve key indicators such as high-performance scratch resistance, wear resistance, and corrosion resistance, and fundamentally meet the engineering requirements of steel substitution with plastics in complex application environments. Summary of the Invention

[0004] (1) Technical Problems to be Solved The object of the present invention is to provide a high-performance scratch-resistant, wear-resistant and corrosion-resistant nylon material substituting steel with plastic, so as to solve the problem of insufficient scratch resistance, wear resistance and corrosion resistance of current nylon materials.

[0005] (2) Technical solution In order to achieve the above object, the present invention provides the following technical solution: A high-performance scratch-resistant, wear-resistant and corrosion-resistant nylon material substituting steel with plastic, by weight parts, comprises the following components: 5.0 - 15.0 parts of surface-modified calcium fluoride@aluminum oxide whisker filler, 3.5 - 8.0 parts of polytetrafluoroethylene-coated boron nitride particles, 50.0 - 90.0 parts of nylon matrix resin, 1.0 - 3.0 parts of compatibilizer, 0.1 - 0.5 parts of antioxidant, and 0.4 - 1.0 parts of lubricant.

[0006] The surface-modified calcium fluoride@aluminum oxide whisker filler is obtained by surface-modifying calcium fluoride@aluminum oxide whisker with 3,3,3-trifluoropropyltrimethoxysilane; The calcium fluoride@aluminum oxide whisker consists of aluminum oxide whisker and a calcium fluoride nanolayer loaded on the surface of the aluminum oxide whisker; The polytetrafluoroethylene-coated boron nitride particles consist of boron nitride particles and a polytetrafluoroethylene coating layer coated on the surface of the boron nitride particles; Furthermore, the average diameter of the surface-modified calcium fluoride@aluminum oxide whisker is 500 - 4500 nm, and the average length is 4.5 - 7.0 μm; the thickness of the calcium fluoride nanolayer is 80 - 150 nm; Furthermore, the preparation method of the surface-modified calcium fluoride@aluminum oxide whisker filler is as follows: by weight parts, 100 parts of calcium fluoride@aluminum oxide whisker filler are dispersed in 300 - 500 parts of an ethanol and water mixed solvent, the weight ratio of ethanol to water is 3:1 - 1:1, after ultrasonic treatment for 10 - 30 min until evenly dispersed, 0.5 - 3 parts of 3,3,3-trifluoropropyltrimethoxysilane coupling agent is added, and the mixture is continuously stirred and reacted at 50 - 90 °C with a stirring rate of 200 - 500 rpm for 3 - 8 h. Subsequently, a vacuum filtration device is used to separate the solid and liquid phases, the solid phase is retained and washed with ethanol 3 - 5 times to remove the unreacted coupling agent, and finally the product is placed in an oven at 80 - 120 °C and dried for 2 - 4 h to obtain the surface-modified calcium fluoride@aluminum oxide whisker filler.

[0007] Further, the preparation method of the calcium fluoride@aluminum oxide whiskers is as follows: by weight, 100 parts of aluminum oxide whiskers are dispersed in 200 - 500 parts of deionized water, and ultrasonic treatment is carried out for 10 - 60 min to form a uniform suspension. Under continuous stirring at a stirring rate of 200 - 800 rpm, 5 - 20 parts of calcium chloride and 3 - 15 parts of an ammonium fluoride aqueous solution with a concentration of 0.1 - 1.5 mol / L are added in sequence. The pH is adjusted to 8 - 11, and an in-situ crystallization precipitation reaction is carried out at 50 - 80 °C for 60 - 180 min. After the reaction, it is washed 3 - 5 times with deionized water and vacuum filtered to remove soluble by-products and unreacted ions. The solid phase is retained and dried at 80 - 120 °C for 2 - 6 h to obtain the calcium fluoride@aluminum oxide whisker composite powder.

[0008] Further, the preparation method of the aluminum oxide whiskers is as follows: by weight, 5 - 20 parts of aluminum nitrate are dissolved in 50 - 200 parts of deionized water to form an aluminum salt solution. 3 - 8 parts of polyethylene glycol are added and mixed evenly under the condition of a stirring rate of 200 - 800 rpm. 3 - 15 parts of 5wt.% ammonia water are slowly added dropwise to make the pH of the solution 8 - 12 to form aluminum hydroxide colloid. The mixed solution is transferred to a high-pressure hydrothermal reaction kettle and reacted at 150 - 250 °C for 6 - 24 h. After the reaction, it is cooled to 25 - 60 °C, the liquid phase is separated by vacuum filtration, and the solid phase is washed 3 - 5 times with deionized water to remove the residual template agent and soluble ions. The solid phase is retained and dried at 80 - 120 °C for 2 - 6 h, and then placed in a calcination furnace and heated to 600 - 1000 °C at a heating rate of 2 - 10 °C / min for calcination for 2 - 6 h to obtain aluminum oxide whiskers.

[0009] The present invention adopts the design of surface-modified calcium fluoride@aluminum oxide whisker filler, which is mainly used to enhance the scratch resistance, wear resistance and corrosion resistance of nylon materials. By constructing a calcium fluoride@aluminum oxide whisker structure with aluminum oxide whiskers as the skeleton and a calcium fluoride nanolayer loaded on the surface, not only excellent mechanical strength and thermal stability are imparted to the filler, but also its chemical stability and interfacial functional characteristics in complex environments are further improved. As the main reinforcing phase, aluminum oxide whiskers have good size regularity and high aspect ratio, and can effectively transfer stress and inhibit the propagation of microcracks in the composite material, significantly improving the scratch resistance and wear resistance of the material; while the introduction of the calcium fluoride nanolayer improves the surface reactivity and corrosion resistance of the whiskers, providing guarantee for the stable use of the material in corrosive media such as acids and alkalis. On this basis, the calcium fluoride@aluminum oxide whiskers are surface-modified by 3,3,3-trifluoropropyltrimethoxysilane to further enhance their dispersibility and interfacial compatibility in the polar nylon matrix, enabling the filler to form a uniform and stable distribution state in the resin system, and then realizing the synergistic optimization of structural continuity and performance balance. Through the multi-level regulation and surface functionalization treatment of the whisker structure, this technical solution forms a composite synergistic effect in terms of mechanical enhancement and chemical protection, significantly improving the comprehensive service ability of nylon materials under various working conditions, and reflecting the systematicness and efficiency of the material construction strategy.

[0010] Further, the preparation method of the polytetrafluoroethylene-coated boron nitride particles is as follows: by weight, 100 parts of boron nitride particles are dispersed in 300 - 800 parts of aqueous polytetrafluoroethylene dispersion, the solid content of the polytetrafluoroethylene dispersion is 30 - 60 wt.%, and after being treated by ultrasonic power of 300 - 1000 W for 15 - 90 min to form a uniform suspension system, 2.0 - 5.0 parts of sodium dodecyl sulfate is added as a dispersant and mixed evenly under the condition of a stirring rate of 300 - 1000 rpm. Hydrochloric acid or ammonia water with a concentration of 5 - 10 wt% is added dropwise to adjust the pH to 2 - 5, and the temperature is raised to 60 - 100 °C and kept at a constant temperature for 2 - 4 h to enable the in-situ deposition of polytetrafluoroethylene into a film on the particle surface. After the reaction, the liquid phase and uncoated polytetrafluoroethylene particles are removed by vacuum filtration, and the solid phase is retained and ultrasonically washed with absolute ethanol 3 - 5 times to remove surfactants and free ions. Subsequently, the product is transferred to an oven and dried at 100 - 150 °C for 3 - 12 h to obtain the primary coated powder. Then, the powder is placed in a tubular furnace, protected by nitrogen, and heated to 320 - 400 °C at a heating rate of 2 - 10 °C / min and sintered for 1 - 3 h to densify the polytetrafluoroethylene film layer, and finally the polytetrafluoroethylene-coated boron nitride particles are obtained.

[0011] Further, the preparation method of the boron nitride particles is as follows: by weight, 100 parts of hexagonal boron nitride raw material powder with an initial particle size of 5 - 20 μm and a purity of ≥99% is mixed with 500 - 2000 parts of zirconia ball milling media with a diameter of 5 mm. Wet ball milling is carried out using a planetary ball mill with a ball-to-material ratio of 5:1 - 20:1 and a rotation speed of 200 - 600 rpm. 100 - 500 parts of deionized water and 2 - 5 parts of polyvinylpyrrolidone are added to form a slurry with a solid-to-liquid ratio of 1:1 - 1:5. The filling rate of the ball milling tank is controlled at 50 - 70% and the ball milling time is 10 - 20 h. During the process, the temperature is maintained ≤60°C to avoid the destruction of the boron nitride structure. After ball milling, the ball milling media are removed by centrifugal separation and a boron nitride suspension with a particle size of ≤3 μm is retained. Subsequently, the suspension is vacuum dried at 60 - 100°C for 4 - 12 h to remove the dispersion medium, and then subjected to a deagglomeration treatment using a jet mill at a pressure of 0.5 - 1.2 MPa. Finally, the boron nitride particles are obtained by calcining at 800 - 1200°C for 1 - 2 h in a nitrogen atmosphere with a heating rate of 5 - 10°C / min.

[0012] Further, the average diameter of the polytetrafluoroethylene-coated boron nitride particles is 200 - 800 nm; the thickness of the polytetrafluoroethylene coating layer is 30 - 80 nm; Further, the nylon matrix resin is a mixture of PA6 and PA66 in a mass ratio of (60 - 80):(40 - 20); Further, the compatibilizer is polyethylene grafted maleic anhydride; Further, the antioxidant is antioxidant 1010; Further, the lubricant is ethylene bisstearamide.

[0013] The present invention adopts the design of polytetrafluoroethylene-coated boron nitride particles, which is mainly used to enhance the scratch resistance, wear resistance and corrosion resistance of nylon materials. By preparing boron nitride particles with a reasonable particle size distribution from the initial hexagonal boron nitride raw materials through steps such as wet ball milling, deagglomeration and high-temperature calcination, and in-situ depositing a polytetrafluoroethylene coating layer on its surface, it not only endows it with good lubricity and thermal stability, but also significantly improves its dispersibility and interfacial compatibility in the nylon matrix. The polytetrafluoroethylene coating layer forms a dense coating structure during the high-temperature sintering process, which can effectively limit the agglomeration of boron nitride, improve its uniform distribution in the polymer matrix, and form a stable lubricating interface during the use of the material, thereby reducing the friction coefficient and slowing down surface wear. At the same time, boron nitride itself has excellent chemical inertness and corrosion resistance characteristics, which can significantly improve the stability of the composite material in acidic, alkaline or humid and hot environments. By adjusting the coating layer thickness and particle size, the dual regulation of the interface microstructure and macroscopic properties is realized, so that the material can still maintain good functional stability under long-term friction impact and the action of external corrosive media. In addition, the present invention introduces polyethylene grafted maleic anhydride as a compatibilizer into the nylon matrix, which helps to form a stronger interfacial bond between the filler and the matrix and improve the overall structural integrity of the composite system; at the same time, through the synergistic introduction of antioxidant 1010 and ethylene bisstearamide, the antioxidant ability and processing fluidity of the material are further enhanced. In the overall design, the polytetrafluoroethylene-coated boron nitride particles not only provide the functions of lubrication and stability, but also form good synergistic effects with other additives and the nylon matrix, realizing multiple improvements in the scratch resistance, wear resistance and corrosion resistance of the material, and fully reflecting the design concept of structural optimization and performance integration of multiphase composite materials.

[0014] (3) Beneficial technical effects 1. Through the synergistic design of the structural strengthening and surface modification of calcium fluoride@aluminum oxide whiskers, the present invention significantly improves the comprehensive performance of nylon materials in high-wear and strong-corrosion environments, solves the problem of poor durability of existing materials, and has excellent engineering application value.

[0015] 2. Through the synergistic design of polytetrafluoroethylene-coated boron nitride particles and various additives, the present invention realizes a significant improvement in the scratch resistance, wear resistance and corrosion resistance of nylon materials under complex working conditions, and has excellent interfacial stability and application reliability. Description of the drawings

[0016] Figure 1 It is the morphology diagram of the aluminum oxide whiskers prepared in Example 1 of the present invention.

[0017] Figure 2 It is the XRD phase analysis diagram of the aluminum oxide whiskers prepared in Example 1 of the present invention.

[0018] Figure 3Morphology diagram of the modified calcium fluoride@aluminum oxide whisker filler prepared in Example 1 of the present invention.

[0019] Figure 4 XRD phase analysis diagram of the modified calcium fluoride@aluminum oxide whisker filler prepared in Example 1 of the present invention.

[0020] Figure 5 Morphology diagram of the boron nitride particles prepared in Example 1 of the present invention.

[0021] Figure 6 XRD phase analysis diagram of the boron nitride particles prepared in Example 1 of the present invention.

[0022] Figure 7 Morphology diagram of the polytetrafluoroethylene-coated boron nitride particles prepared in Example 1 of the present invention. Detailed implementation manners

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0024] Example 1: A high-performance scratch-resistant, wear-resistant, and corrosion-resistant steel-substituting nylon material, by weight, includes the following components: 5.0 parts of surface-modified calcium fluoride@aluminum oxide whisker filler, 3.5 parts of polytetrafluoroethylene-coated boron nitride particles, 50.0 parts of nylon matrix resin, 1.0 part of compatibilizer, 0.1 part of antioxidant, and 0.4 part of lubricant.

[0025] The surface-modified calcium fluoride@aluminum oxide whisker filler in this example is obtained by surface-modifying calcium fluoride@aluminum oxide whiskers with 3,3,3-trifluoropropyltrimethoxysilane; the calcium fluoride@aluminum oxide whiskers are composed of aluminum oxide whiskers and calcium fluoride nanolayers loaded on the surface of the aluminum oxide whiskers; the polytetrafluoroethylene-coated boron nitride particles are composed of boron nitride particles and polytetrafluoroethylene coating layers coated on the surface of the boron nitride particles; The average diameter of the surface-modified calcium fluoride@aluminum oxide whiskers in this example is 500 nm, and the average length is 4.5 μm; the thickness of the calcium fluoride nanolayer is 80 nm; The preparation method of the surface-modified calcium fluoride@aluminum oxide whisker filler in this example is as follows: by weight, 100 parts of calcium fluoride@aluminum oxide whisker filler are dispersed in 300 parts of a mixed solvent of ethanol and water, the weight ratio of ethanol to water is 3:1. After ultrasonic treatment for 10 min until evenly dispersed, 0.5 part of 3,3,3-trifluoropropyltrimethoxysilane coupling agent is added, and the reaction is continuously stirred at a stirring rate of 200 rpm at 50 °C for 3 h. Subsequently, a vacuum filtration device is used to separate the solid and liquid phases, the solid phase is retained and washed 3 times with ethanol to remove the unreacted coupling agent. Finally, the product is placed in an oven at 80 °C and dried for 2 h to obtain the surface-modified calcium fluoride@aluminum oxide whisker filler.

[0026] The preparation method of the calcium fluoride@aluminum oxide whisker in this example is as follows: by weight, 100 parts of aluminum oxide whiskers are dispersed in 200 parts of deionized water. After ultrasonic treatment for 10 min to form a homogeneous suspension, 5 parts of calcium chloride and 3 parts of an aqueous solution of ammonium fluoride with a concentration of 0.1 mol / L are successively added under continuous stirring at a stirring rate of 200 rpm. The pH is adjusted to 8 and an in-situ crystallization precipitation reaction is carried out at 50 °C for 60 min. After the reaction, it is washed 3 times with deionized water and vacuum filtered to remove soluble by-products and unreacted ions. The solid phase is retained and dried at 80 °C for 2 h to obtain the calcium fluoride@aluminum oxide whisker composite powder.

[0027] The preparation method of the aluminum oxide whisker in this example is as follows: by weight, 5 parts of aluminum nitrate are dissolved in 50 parts of deionized water to form an aluminum salt solution. 3 parts of polyethylene glycol are added and mixed evenly under the condition of a stirring rate of 200 rpm. 3 parts of 5 wt.% ammonia water are slowly added dropwise to make the pH of the solution 8 to form aluminum hydroxide colloid. The mixed solution is transferred to a high-pressure hydrothermal reaction kettle and reacted at 150 °C for 6 h. After the reaction, it is cooled to 25 °C, the liquid phase is separated by vacuum filtration, and the solid phase is washed 3 times with deionized water to remove the residual template agent and soluble ions. The solid phase is retained and dried at 80 °C for 2 h, and then placed in a calcination furnace and heated to 600 °C at a heating rate of 2 °C / min and calcined for 2 h to obtain the aluminum oxide whisker.

[0028] The preparation method of the polytetrafluoroethylene-coated boron nitride particles in this example is as follows: By weight, 100 parts of boron nitride particles are dispersed in 450 parts of an aqueous polytetrafluoroethylene dispersion. The solid content of the polytetrafluoroethylene dispersion is 39 wt.%. It is treated with an ultrasonic power of 510 W for 38 min to form a uniform suspension system. 2.9 parts of sodium dodecyl sulfate are added as a dispersant and mixed evenly under the condition of a stirring rate of 510 rpm. Hydrochloric acid or ammonia water with a concentration of 7 wt% is added dropwise to adjust the pH to 3. The temperature is raised to 72 °C and kept reacting for 3 h to deposit polytetrafluoroethylene in situ on the particle surface to form a film. After the reaction, the liquid phase and uncoated polytetrafluoroethylene microparticles are removed by vacuum filtration. The solid phase is retained and ultrasonically washed 4 times with absolute ethanol to remove the surfactant and free ions. Subsequently, the product is transferred to an oven and dried at 115 °C for 6 h to obtain the primary coated powder. Then, the powder is placed in a tube furnace, purged with nitrogen, and heated to 344 °C at a heating rate of 4 °C / min and sintered for 2 h to densify the polytetrafluoroethylene film layer, and finally, polytetrafluoroethylene-coated boron nitride particles are obtained.

[0029] The preparation method of the boron nitride particles in this example is as follows: By weight, 100 parts of hexagonal boron nitride raw material powder with an initial particle size of 10 μm and a purity of ≥99% is mixed with 950 parts of zirconia ball milling media with a diameter of 5 mm. A planetary ball mill is used for wet ball milling at a ball-to-material ratio of 9.5:1 and a rotation speed of 320 rpm. 220 parts of deionized water and 3 parts of polyvinylpyrrolidone are added to form a slurry with a solid-to-liquid ratio of 1:2.2. The filling rate of the ball mill tank is controlled at 56% and the ball milling time is 13 h. The temperature is maintained ≤60 °C during the process to avoid damage to the boron nitride structure. After the ball milling is completed, the ball milling media are removed by centrifugal separation and the boron nitride suspension with a particle size ≤3 μm is retained. Subsequently, the suspension is vacuum dried at 72 °C for 6 h to remove the dispersion medium, and then subjected to a deagglomeration treatment with a gas flow pulverizer at a pressure of 0.7 MPa. Finally, it is calcined at a heating rate of 7 °C / min to 920 °C for 1 h in a nitrogen atmosphere to obtain boron nitride particles.

[0030] The average diameter of the polytetrafluoroethylene-coated boron nitride particles in this example is 380 nm; the thickness of the polytetrafluoroethylene coating layer is 45 nm; The nylon matrix resin in this example is a mixture of PA6 and PA66 with a mass ratio of 66:34; The compatibilizer in this example is polyethylene grafted maleic anhydride; the antioxidant is antioxidant 1010; the lubricant is ethylene bisstearamide.

[0031] Figure 1 and Figure 3It shows the typical one-dimensional whisker structure of alumina whiskers and the modified filler after their combination with calcium fluoride in Example 1 of the present invention, indicating that the prepared materials have good morphological uniformity and structural continuity, which helps to enhance the mechanical properties and interfacial bonding of the composite materials; Figure 2 and Figure 4 are respectively the XRD phase analysis diagrams of alumina whiskers and their modified composites, both showing the characteristic diffraction peaks of γ-Al2O3, verifying that the transition-phase alumina with a high specific surface area and an active surface is formed under high-temperature calcination conditions, and the introduction of calcium fluoride does not change its crystal structure, demonstrating good structural stability; Figure 5 and Figure 7 respectively show the microscopic morphologies of boron nitride particles and those after being coated with polytetrafluoroethylene. The particles are evenly distributed and have a moderate particle size, which is beneficial to improving the dispersibility and lubrication performance; Figure 6 Typical diffraction peaks of the hexagonal structure appear in the shown XRD spectrum of boron nitride, further verifying that the boron nitride particles have a complete crystal structure. In summary, Figures 1 to 7 the characterization results jointly verify the successful preparation, complete structure and good compatibility of each component material in the present invention, providing strong support for their synergistic improvement of mechanical, wear-resistant and chemical-resistant properties in the composite system.

[0032] Example 2: A high-performance scratch-resistant, wear-resistant and corrosion-resistant steel-substituted nylon material made of plastics, which, by weight, comprises the following components: 8 parts of surface-modified calcium fluoride@alumina whisker filler, 4.9 parts of polytetrafluoroethylene-coated boron nitride particles, 62 parts of nylon matrix resin, 1.6 parts of compatibilizer, 0.2 parts of antioxidant, and 0.6 parts of lubricant.

[0033] The surface-modified calcium fluoride@alumina whisker filler in this example is obtained by surface-modifying calcium fluoride@alumina whiskers with 3,3,3-trifluoropropyltrimethoxysilane; the calcium fluoride@alumina whiskers are composed of alumina whiskers and a calcium fluoride nanolayer loaded on the surface of the alumina whiskers; the polytetrafluoroethylene-coated boron nitride particles are composed of boron nitride particles and a polytetrafluoroethylene coating layer coated on the surface of the boron nitride particles; The average diameter of the surface-modified calcium fluoride@alumina whiskers in this example is 1700 nm, and the average length is 5.3 μm; the thickness of the calcium fluoride nanolayer is 101 nm; The preparation method of the surface-modified calcium fluoride@aluminum oxide whisker filler in this example is as follows: by weight, 100 parts of the calcium fluoride@aluminum oxide whisker filler are dispersed in a mixed solvent of 360 parts of ethanol and water, and the weight ratio of ethanol to water is 2.4:1. After ultrasonic treatment for 16 min until evenly dispersed, 1.3 parts of 3,3,3-trifluoropropyltrimethoxysilane coupling agent are added, and the mixture is continuously stirred and reacted at 62 °C at a stirring rate of 290 rpm for 5 h. Subsequently, a vacuum filtration device is used to separate the solid and liquid phases, the solid phase is retained and washed 4 times with ethanol to remove the unreacted coupling agent. Finally, the product is placed in an oven at 92 °C and dried for 3 h to obtain the surface-modified calcium fluoride@aluminum oxide whisker filler.

[0034] The preparation method of the calcium fluoride@aluminum oxide whisker in this example is as follows: by weight, 100 parts of aluminum oxide whiskers are dispersed in 290 parts of deionized water, and after ultrasonic treatment for 25 min to form a homogeneous suspension, 10 parts of calcium chloride and 7 parts of an aqueous solution of ammonium fluoride with a concentration of 0.5 mol / L are successively added under continuous stirring at a stirring rate of 380 rpm. The pH is adjusted to 9 and an in-situ crystallization precipitation reaction is carried out at 59 °C for 96 min. After the reaction, it is washed 4 times with deionized water and vacuum filtered to remove soluble by-products and unreacted ions. The solid phase is retained and dried at 92 °C for 3 h to obtain the calcium fluoride@aluminum oxide whisker composite powder.

[0035] The preparation method of the aluminum oxide whisker in this example is as follows: by weight, 10 parts of aluminum nitrate are dissolved in 95 parts of deionized water to form an aluminum salt solution, 5 parts of polyethylene glycol are added and mixed evenly under stirring at a stirring rate of 380 rpm. 7 parts of 5 wt.% ammonia water are slowly added dropwise to make the pH of the solution 9 to form aluminum hydroxide colloid. The mixture is transferred to a high-pressure hydrothermal reaction kettle and reacted at 180 °C for 11 h. After the reaction, it is cooled to 36 °C, the liquid phase is separated by vacuum filtration, and the solid phase is washed 4 times with deionized water to remove the residual template agent and soluble ions. The solid phase is retained and dried at 92 °C for 3 h and then placed in a calcination furnace and heated to 720 °C at a heating rate of 4 °C / min and calcined for 3 h to obtain the aluminum oxide whisker.

[0036] The preparation method of the polytetrafluoroethylene-coated boron nitride particles in this example is as follows: By weight, 100 parts of boron nitride particles are dispersed in 300 parts of an aqueous polytetrafluoroethylene dispersion. The solid content of the polytetrafluoroethylene dispersion is 30 wt.%. After being treated with an ultrasonic power of 300 W for 15 min to form a uniform suspension system, 2.0 parts of sodium dodecyl sulfate are added as a dispersant and mixed evenly under the condition of a stirring rate of 300 rpm. Hydrochloric acid or ammonia water with a concentration of 5 wt% is added dropwise to adjust the pH to 2. The temperature is raised to 60 °C and kept reacting for 2 h to deposit polytetrafluoroethylene in situ on the particle surface to form a film. After the reaction, the liquid phase and uncoated polytetrafluoroethylene particles are removed by vacuum filtration. The solid phase is retained and ultrasonically washed 3 times with absolute ethanol to remove the surfactant and free ions. Subsequently, the product is transferred to an oven and dried at 100 °C for 3 h to obtain a primary coated powder. Then, the powder is placed in a tubular furnace, purged with nitrogen, and heated to 320 °C at a heating rate of 2 °C / min and sintered for 1 h to densify the polytetrafluoroethylene film layer, and finally, polytetrafluoroethylene-coated boron nitride particles are obtained.

[0037] The preparation method of the boron nitride particles in this example is as follows: By weight, 100 parts of hexagonal boron nitride raw material powder with an initial particle size of 5 μm and a purity of ≥99% is mixed with 500 parts of zirconia ball milling media with a diameter of 5 mm. A planetary ball mill is used for wet ball milling at a ball-to-material ratio of 5:1 and a rotation speed of 200 rpm. 100 parts of deionized water and 2 parts of polyvinylpyrrolidone are added to form a slurry with a solid-to-liquid ratio of 1:1. The filling rate of the ball mill tank is controlled to be 50% and the ball milling time is 10 h. During the process, the temperature is maintained ≤60 °C to avoid damage to the boron nitride structure. After the ball milling is completed, the ball milling media are removed by centrifugal separation and the boron nitride suspension with a particle size ≤3 μm is retained. Subsequently, the suspension is vacuum dried at 60 °C for 4 h to remove the dispersion medium, and then subjected to a deagglomeration treatment with a gas flow pulverizer at a pressure of 0.5 MPa. Finally, it is calcined at 800 °C at a heating rate of 5 °C / min for 1 h in a nitrogen atmosphere to obtain boron nitride particles.

[0038] The average diameter of the polytetrafluoroethylene-coated boron nitride particles in this example is 200 nm; the thickness of the polytetrafluoroethylene coating layer is 30 nm; The nylon matrix resin in this example is a mixture of PA6 and PA66 with a mass ratio of 60:40; The compatibilizer in this example is polyethylene grafted maleic anhydride; the antioxidant is antioxidant 1010; the lubricant is ethylene bisstearamide.

[0039] Example 3: A high-performance scratch-resistant, wear-resistant, and corrosion-resistant nylon material that replaces steel with plastic, comprising the following components, measured by weight: 15.0 parts of surface-modified calcium fluoride @ alumina whisker filler, 8.0 parts of polytetrafluoroethylene-coated boron nitride particles, 90.0 parts of nylon matrix resin, 3.0 parts of a compatibilizer, 0.5 parts of an antioxidant, and 1.0 parts of a lubricant.

[0040] The surface-modified calcium fluoride@alumina whisker filler of this embodiment is obtained by surface-modifying calcium fluoride@alumina whiskers with 3,3,3-trifluoropropyltrimethoxysilane; the calcium fluoride@alumina whiskers are composed of alumina whiskers and a calcium fluoride nanolayer supported on the surface of the alumina whiskers; the polytetrafluoroethylene-coated boron nitride particles are composed of boron nitride particles and a polytetrafluoroethylene coating layer coated on the surface of the boron nitride particles; The surface-modified calcium fluoride@aluminum oxide whiskers of this embodiment have an average diameter of 4500 nm and an average length of 7.0 μm; the thickness of the calcium fluoride nanolayer is 150 nm; The preparation method of the surface modified calcium fluoride @ alumina whisker filler of the present embodiment is as follows: by weight, 100 parts of calcium fluoride @ alumina whisker filler are dispersed in 500 parts of a mixed solvent of ethanol and water, wherein the weight ratio of ethanol to water is 1:1; after ultrasonic treatment for 30 minutes until the mixture is uniformly dispersed, 3 parts of 3,3,3-trifluoropropyltrimethoxysilane coupling agent are added; the mixture is stirred at 90° C. and the stirring rate is 500 rpm for 8 hours; the solid and liquid phases are then separated by a vacuum filtration device; the solid phase is retained and washed with ethanol for 5 times to remove the unreacted coupling agent; the product is finally dried in an oven at 120° C. for 4 hours to obtain the surface modified calcium fluoride @ alumina whisker filler.

[0041] The preparation method of calcium fluoride @ alumina whisker of the present embodiment is as follows: by weight, 100 parts of alumina whisker are dispersed in 500 parts of deionized water, and a uniform suspension is formed by ultrasonic treatment for 60 minutes, 20 parts of calcium chloride and 15 parts of 1.5 mol / L ammonium fluoride aqueous solution are added in sequence under continuous stirring at a stirring rate of 800 rpm, the pH is adjusted to 11, and an in-situ crystallization precipitation reaction is carried out at 80° C. for 180 minutes. After the reaction is completed, the mixture is washed with deionized water for 5 times and vacuum filtered to remove soluble by-products and unreacted ions, and the solid phase is retained and dried at 120° C. for 6 hours to obtain a calcium fluoride @ alumina whisker composite powder.

[0042] The preparation method of the alumina whiskers in this embodiment is as follows: by weight, 20 parts of aluminum nitrate are dissolved in 200 parts of deionized water to form an aluminum salt solution, 8 parts of polyethylene glycol are added and mixed evenly under the condition that the stirring rate is 800 rpm, 15 parts of 5 wt.% ammonia water are slowly added dropwise to make the pH of the solution 12 to form aluminum hydroxide colloid, the mixed solution is transferred to a high-pressure hydrothermal reaction kettle and reacted at 250 °C for 24 h, after the reaction, it is cooled to 60 °C, the liquid phase is separated by vacuum filtration, and the solid phase is washed 5 times with deionized water to remove the residual template agent and soluble ions, the solid phase is retained and dried at 120 °C for 6 h, and then placed in a calcination furnace and heated to 1000 °C at a heating rate of 10 °C / min and calcined for 6 h to obtain alumina whiskers.

[0043] The preparation method of the polytetrafluoroethylene-coated boron nitride particles in this embodiment is as follows: by weight, 100 parts of boron nitride particles are dispersed in 800 parts of an aqueous polytetrafluoroethylene dispersion, the solid content of the polytetrafluoroethylene dispersion is 60 wt.%, and it is treated with an ultrasonic power of 1000 W for 90 min to form a uniform suspension system, 5.0 parts of sodium dodecyl sulfate are added as a dispersant and mixed evenly under the condition that the stirring rate is 1000 rpm, 10 wt% hydrochloric acid or ammonia water is added dropwise to adjust the pH to 5, the temperature is raised to 100 °C and kept reacting for 4 h to deposit polytetrafluoroethylene in situ on the particle surface to form a film, after the reaction, the liquid phase and uncoated polytetrafluoroethylene particles are removed by vacuum filtration, the solid phase is retained and ultrasonically washed 5 times with absolute ethanol to remove the surfactant and free ions, then the product is transferred to an oven and dried at 150 °C for 12 h to obtain a primary coated powder, and then the powder is placed in a tubular furnace, nitrogen is introduced for protection, and it is heated to 400 °C at a heating rate of 10 °C / min and sintered for 3 h to densify the polytetrafluoroethylene film layer, and finally polytetrafluoroethylene-coated boron nitride particles are obtained.

[0044] The preparation method of the boron nitride particles in this embodiment is as follows: by weight, 100 parts of hexagonal boron nitride raw material powder with an initial particle size of 20 μm and a purity ≥ 99% are mixed with 2000 parts of zirconia ball milling media with a diameter of 5 mm, a planetary ball mill is used for wet ball milling at a ball-to-material ratio of 20:1 and a rotation speed of 600 rpm, 500 parts of deionized water and 5 parts of polyvinylpyrrolidone are added to form a slurry with a solid-to-liquid ratio of 1:5, the filling rate of the ball mill tank is controlled to be 70% and the ball milling time is 20 h, and the temperature is maintained ≤ 60 °C during the process to avoid the destruction of the boron nitride structure. After the ball milling is completed, the ball milling media are removed by centrifugal separation and the boron nitride suspension with a particle size ≤ 3 μm is retained. Then the suspension is vacuum dried at 100 °C for 12 h to remove the dispersion medium, and then deagglomerated by a jet mill at a pressure of 1.2 MPa. Finally, it is calcined in a nitrogen atmosphere at a heating rate of 10 °C / min to 1200 °C for 2 h to obtain boron nitride particles.

[0045] The average diameter of the polytetrafluoroethylene-coated boron nitride particles in this example is 800 nm; the thickness of the polytetrafluoroethylene coating layer is 80 nm; The nylon matrix resin in this example is a mixture of PA6 and PA66 with a mass ratio of 80:20; The compatibilizer in this example is polyethylene grafted maleic anhydride; the antioxidant is antioxidant 1010; the lubricant is ethylene bis-stearamide.

[0046] Example 4: A high-performance scratch-resistant, wear-resistant and corrosion-resistant steel-substituted nylon material, by weight, includes the following components: 11 parts of surface-modified calcium fluoride@aluminum oxide whisker filler, 6.2 parts of polytetrafluoroethylene-coated boron nitride particles, 74 parts of nylon matrix resin, 2.2 parts of compatibilizer, 0.3 parts of antioxidant, and 0.8 parts of lubricant.

[0047] The surface-modified calcium fluoride@aluminum oxide whisker filler in this example is obtained by surface-modifying calcium fluoride@aluminum oxide whiskers with 3,3,3-trifluoropropyltrimethoxysilane; the calcium fluoride@aluminum oxide whiskers are composed of aluminum oxide whiskers and calcium fluoride nanolayers loaded on the surface of the aluminum oxide whiskers; the polytetrafluoroethylene-coated boron nitride particles are composed of boron nitride particles and a polytetrafluoroethylene coating layer coated on the surface of the boron nitride particles; The average diameter of the surface-modified calcium fluoride@aluminum oxide whiskers in this example is 2900 nm, and the average length is 6.0 μm; the thickness of the calcium fluoride nanolayer is 122 nm; The preparation method of the surface-modified calcium fluoride@aluminum oxide whisker filler in this example is: by weight, disperse 100 parts of calcium fluoride@aluminum oxide whisker filler in a mixed solvent of 420 parts of ethanol and water, the weight ratio of ethanol to water is 1.8:1, after ultrasonic treatment for 22 min until evenly dispersed, add 2.0 parts of 3,3,3-trifluoropropyltrimethoxysilane coupling agent, continuously stir and react at 74 °C with a stirring rate of 380 rpm for 6 h, then use a vacuum filtration device to separate the solid and liquid phases, retain the solid phase and wash it 4 times with ethanol to remove the unreacted coupling agent, and finally place the product in an oven at 104 °C for 3 h to obtain the surface-modified calcium fluoride@aluminum oxide whisker filler.

[0048] The preparation method of calcium fluoride@aluminum oxide whiskers in this example is as follows: by weight, 100 parts of aluminum oxide whiskers are dispersed in 380 parts of deionized water, and after ultrasonic treatment for 40 min, a uniform suspension is formed. Under continuous stirring at a stirring rate of 560 rpm, 14 parts of calcium chloride and 10 parts of an ammonium fluoride aqueous solution with a concentration of 0.9 mol / L are added in sequence. The pH is adjusted to 10, and an in-situ crystallization precipitation reaction is carried out at 68 °C for 132 min. After the reaction, it is washed 4 times with deionized water and vacuum filtered to remove soluble by-products and unreacted ions. The solid phase is retained and dried at 104 °C for 4 h to obtain calcium fluoride@aluminum oxide whisker composite powder.

[0049] The preparation method of aluminum oxide whiskers in this example is as follows: by weight, 14 parts of aluminum nitrate are dissolved in 140 parts of deionized water to form an aluminum salt solution. 6 parts of polyethylene glycol are added and mixed evenly under stirring at a stirring rate of 560 rpm. 10 parts of 5 wt.% ammonia water are slowly added dropwise to adjust the pH of the solution to 10 to form aluminum hydroxide colloid. The mixed solution is transferred to a high-pressure hydrothermal reaction kettle and reacted at 210 °C for 17 h. After the reaction, it is cooled to 47 °C, the liquid phase is separated by vacuum filtration, and the solid phase is washed 4 times with deionized water to remove residual template agents and soluble ions. The solid phase is retained, dried at 104 °C for 4 h, and then placed in a calcination furnace and heated to 840 °C at a heating rate of 7 °C / min for calcination for 4 h to obtain aluminum oxide whiskers.

[0050] The preparation method of polytetrafluoroethylene-coated boron nitride particles in this example is as follows: by weight, 100 parts of boron nitride particles are dispersed in 600 parts of an aqueous polytetrafluoroethylene dispersion. The solid content of the polytetrafluoroethylene dispersion is 48 wt.%. After ultrasonic treatment at an ultrasonic power of 720 W for 60 min, a uniform suspension system is formed. 3.8 parts of sodium dodecyl sulfate are added as a dispersant and mixed evenly under stirring at a stirring rate of 720 rpm. 8 wt% hydrochloric acid or ammonia water is added dropwise to adjust the pH to 4. The temperature is raised to 84 °C and kept at a constant temperature for 3 h to deposit polytetrafluoroethylene in-situ on the particle surface to form a film. After the reaction, the liquid phase and uncoated polytetrafluoroethylene particles are removed by vacuum filtration. The solid phase is retained and ultrasonically washed 4 times with absolute ethanol to remove surfactants and free ions. Subsequently, the product is transferred to an oven and dried at 130 °C for 8 h to obtain a primary coated powder. Then, the powder is placed in a tube furnace, nitrogen is introduced for protection, and it is heated to 368 °C at a heating rate of 7 °C / min and sintered for 2 h to densify the polytetrafluoroethylene film layer, and finally polytetrafluoroethylene-coated boron nitride particles are obtained.

[0051] The preparation method of the boron nitride particles in this example is as follows: by weight, 100 parts of hexagonal boron nitride raw material powder with an initial particle size of 14 μm and a purity of ≥99% is mixed with 1400 parts of zirconia ball milling media with a diameter of 5 mm. Wet ball milling is carried out using a planetary ball mill at a ball-to-material ratio of 14:1 and a rotation speed of 440 rpm, and 340 parts of deionized water and 4 parts of polyvinylpyrrolidone are added to form a slurry with a solid-to-liquid ratio of 1:3.4. The filling rate of the ball milling tank is controlled to be 62% and the ball milling time is 16 h. During the process, the temperature is maintained ≤60°C to avoid the destruction of the boron nitride structure. After ball milling, the ball milling media are removed by centrifugal separation and a boron nitride suspension with a particle size ≤3 μm is retained. Subsequently, the suspension is vacuum dried at 84°C for 8 h to remove the dispersion medium, and then deagglomerated by a jet mill at a pressure of 0.9 MPa. Finally, it is calcined at 1040°C for 2 h in a nitrogen atmosphere at a heating rate of 8°C / min to obtain boron nitride particles.

[0052] The average diameter of the polytetrafluoroethylene-coated boron nitride particles in this example is 560 nm; the thickness of the polytetrafluoroethylene coating layer is 60 nm; The nylon matrix resin in this example is a mixture of PA6 and PA66 with a mass ratio of 72:28; The compatibilizer in this example is polyethylene grafted maleic anhydride; the antioxidant is antioxidant 1010; the lubricant is ethylene bisstearamide.

[0053] Comparative Example 1 It is basically the same as Example 1, except that in the preparation process of the surface-modified calcium fluoride@aluminum oxide whisker filler, 3,3,3-trifluoropropyltrimethoxysilane coupling agent is not used for surface treatment, and the unmodified calcium fluoride@aluminum oxide whisker filler is directly used.

[0054] Comparative Example 2 It is basically the same as Example 1, except that a calcium fluoride layer is not prepared on the surface of the calcium fluoride@aluminum oxide whiskers.

[0055] Comparative Example 3 It is basically the same as Example 1, except that in the preparation process of the calcium fluoride@aluminum oxide whiskers, the pH value of the in-situ crystallization precipitation reaction is adjusted to 6, resulting in the uneven deposition of the calcium fluoride nanolayer on the surface of the aluminum oxide whiskers.

[0056] Comparative Example 4 It is basically the same as Example 1, except that in the preparation of the aluminum oxide whiskers, the hydrothermal reaction temperature is reduced to 100°C.

[0057] Comparative Example 5 It is basically the same as Example 1, except that in the preparation of the polytetrafluoroethylene-coated boron nitride particles, the sintering temperature is set to 280°C, resulting in the incomplete melting and densification of the polytetrafluoroethylene coating layer.

[0058] Comparative Example 6 It is basically the same as Example 1, except that in the ball milling process of boron nitride particles, the ball-to-material ratio is adjusted to 2:1, resulting in insufficient particle crushing efficiency and a final particle size > 3 μm.

[0059] Comparative Example 7 It is basically the same as Example 1, except that in the surface modification process of calcium fluoride@aluminum oxide whisker filler, the weight ratio of the mixed solvent of ethanol and water is changed to 5:1, resulting in an abnormal hydrolysis rate of the coupling agent and a decrease in the grafting rate.

[0060] Comparative Example 8 It is basically the same as Example 1, except that the nylon matrix resin only uses a single PA6.

[0061] Comparative Example 9 It is basically the same as Example 1, except that the compatibilizer is replaced with pure polyethylene without grafted maleic anhydride.

[0062] Comparative Example 10 It is basically the same as Example 1, except that the boron nitride particles are not coated with polytetrafluoroethylene.

[0063] Comparative Example 11 It is basically the same as Example 1, except that the thickness of the calcium fluoride layer in the calcium fluoride@aluminum oxide whisker filler is controlled to 40 nm.

[0064] Performance Test: Scratch Resistance Test: Using an instrumented scratch tester, referring to the ASTM D7027-13 standard, applying a linearly increasing load of 0.1 - 20 N on the material surface with a conical diamond indenter (apex angle 120°, tip radius 50 μm), scratching at a speed of 1 mm / s, recording the critical load (Lc) and scratch depth, and analyzing the scratch morphology (such as plastic deformation or crack propagation) through an optical microscope. This experiment can quantify the ability of the material to resist scratching by sharp objects.

[0065] Reciprocating Sliding Wear Test: Based on the improvement of the ASTM G65-16(2021) dry sand / rubber wheel wear test, using a ring-block friction and wear testing machine, rubbing the material specimen (10×10×5 mm³) against a GCr15 steel counter ring (HRC 60) at a load of 10 N and a speed of 0.3 m / s for 10 4 cycles, measuring the volume loss rate (mm³ / N·m) through a 3D profilometer to verify the improvement effect of its wear resistance.

[0066] Chemical corrosion resistance experiment: According to the ASTM D543-14 standard, material specimens (50×25×3 mm³) were immersed in 5% HCl, 10% NaOH, and xylene solutions (25°C / 72 h) respectively, and the mass change rate (ΔW%) and tensile strength retention rate were measured.

[0067] The properties of the nylon materials in Examples 1-4 and Comparative Examples 1-11 are summarized in Table 1.

[0068] Table 1 Summary of the properties of the nylon materials in Examples 1-4 and Comparative Examples 1-11

[0069] As can be seen from Table 1, the unmodified surface leads to a decrease in the interfacial bonding force between the filler and the nylon matrix, and the load-bearing capacity and anti-wear performance of the material are significantly reduced; the lack of a calcium fluoride layer or uneven deposition thereof will weaken the chemical inert barrier effect and reduce the corrosion resistance and mechanical stability of the material; when the whisker structure is incomplete or the whisker growth is insufficient, its strengthening effect is limited, and it is difficult to effectively transmit stress and inhibit crack propagation; insufficient sintering temperature of the coated boron nitride particles or improper control of the ball-milled particle size will affect the lubricity and dispersibility, resulting in increased wear; poor hydrolysis conditions of the coupling agent will reduce the grafting efficiency, thereby affecting the filler dispersibility and interfacial compatibility; although the high rigidity and increased crystallinity of the single nylon matrix enhance the chemical resistance, they will sacrifice the impact toughness and wear resistance; insufficient polarity or functional groups of the compatibilizer will weaken the interfacial adhesion, resulting in a decrease in the mechanical properties of the composite system; although a too thin calcium fluoride layer can improve the flexibility and local scratch resistance, it cannot effectively block the intrusion of corrosive media, and the overall chemical resistance is reduced.

[0070] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above examples, those of ordinary skill in the art should understand that all equivalent structural transformations made under the concept of the present invention by using the content of the specification and drawings of the present invention should be covered by the protection scope of the claims of the present invention.

Claims

1. A high-performance scratch-resistant, wear-resistant and corrosion-resistant nylon material substituting steel with plastic, characterized in that, By weight parts, it includes the following components: 5.0 to 15.0 parts of surface-modified calcium fluoride@aluminum oxide whisker filler, 3.5 to 8.0 parts of polytetrafluoroethylene-coated boron nitride particles, 50.0 to 90.0 parts of nylon matrix resin, 1.0 to 3.0 parts of compatibilizer, 0.1 to 0.5 parts of antioxidant, and 0.4 to 1.0 parts of lubricant; The surface-modified calcium fluoride@aluminum oxide whisker filler is obtained by surface-modifying calcium fluoride@aluminum oxide whiskers with 3,3,3-trifluoropropyltrimethoxysilane; The calcium fluoride@aluminum oxide whiskers are composed of aluminum oxide whiskers and calcium fluoride nanolayers loaded on the surface of the aluminum oxide whiskers; The polytetrafluoroethylene-coated boron nitride particles are composed of boron nitride particles and a polytetrafluoroethylene coating layer coated on the surface of the boron nitride particles; The aluminum oxide whiskers are prepared by reacting in a high-pressure hydrothermal reactor at 150 to 250 °C for 6 to 24 h; The boron nitride particles are prepared by wet ball milling in a planetary ball mill with a ball-to-material ratio of 5:1 to 20:1 and a rotation speed of 200 to 600 rpm, and after centrifugally separating to remove the ball milling medium, a boron nitride suspension with a particle size ≤ 3 μm is retained; 2. The high-performance scratch-resistant, wear-resistant and corrosion-resistant nylon material substituting steel with plastic according to claim 1, wherein, The average diameter of the surface-modified calcium fluoride@aluminum oxide whiskers is 500 to 4500 nm, and the average length is 4.5 to 7.0 μm; the thickness of the calcium fluoride nanolayer is 80 to 150 nm.

3. A high-performance scratch-resistant, wear-resistant and corrosion-resistant steel-substituting nylon material as claimed in claim 1, characterized in that, The preparation method of the surface-modified calcium fluoride@aluminum oxide whisker filler is: by weight parts, disperse 100 parts of calcium fluoride@aluminum oxide whisker filler in 300 to 500 parts of a mixed solvent of ethanol and water, the weight ratio of ethanol to water is 3:1 to 1:1, after ultrasonic treatment for 10 to 30 min until evenly dispersed, add 0.5 to 3 parts of 3,3,3-trifluoropropyltrimethoxysilane coupling agent, and continuously stir and react at 50 to 90 °C with a stirring rate of 200 to 500 rpm for 3 to 8 h. Subsequently, use a vacuum filtration device to separate the solid-liquid two phases, retain the solid phase and wash it with ethanol 3 to 5 times to remove the unreacted coupling agent. Finally, place the product in an oven at 80 to 120 °C and dry it for 2 to 4 h to obtain the surface-modified calcium fluoride@aluminum oxide whisker filler.

4. The high-performance scratch-resistant, wear-resistant and corrosion-resistant nylon material substituting steel with plastic according to claim 2, wherein The preparation method of the calcium fluoride@aluminum oxide whiskers is: by weight parts, disperse 100 parts of aluminum oxide whiskers in 200 to 500 parts of deionized water, form a uniform suspension after ultrasonic treatment for 10 to 60 min, and sequentially add 5 to 20 parts of calcium chloride and 3 to 15 parts of an ammonium fluoride aqueous solution with a concentration of 0.1 to 1.5 mol / L under continuous stirring at a stirring rate of 200 to 800 rpm, adjust the pH to 8 to 11 and carry out an in-situ crystallization precipitation reaction at 50 to 80 °C for 60 to 180 min. After the reaction, wash it with deionized water 3 to 5 times and vacuum filter to remove soluble by-products and unreacted ions, retain the solid phase and dry it at 80 to 120 °C for 2 to 6 h to obtain the calcium fluoride@aluminum oxide whisker composite powder.

5. A high-performance scratch-resistant, wear-resistant and corrosion-resistant nylon material substituting steel with plastic as claimed in claim 3, characterized in that, The preparation method of the alumina whiskers is as follows: by weight, 5-20 parts of aluminum nitrate are dissolved in 50-200 parts of deionized water to form an aluminum salt solution, 3-8 parts of polyethylene glycol are added and mixed evenly under the condition that the stirring rate is 200-800 rpm, 3-15 parts of 5 wt.% ammonia water are slowly added dropwise to make the pH of the solution 8-12 to form aluminum hydroxide colloid, the mixed solution is transferred to a high-pressure hydrothermal reaction kettle and reacted at 150-250 °C for 6-24 h, after the reaction, it is cooled to 25-60 °C, the liquid phase is separated by vacuum filtration, and the solid phase is washed 3-5 times with deionized water to remove the residual template agent and soluble ions, the solid phase is retained and dried at 80-120 °C for 2-6 h, and then placed in a calcination furnace and heated to 600-1000 °C at a heating rate of 2-10 °C / min for calcination for 2-6 h to obtain alumina whiskers.

6. A high-performance scratch-resistant, wear-resistant and corrosion-resistant nylon material substituting steel with plastic as described in claim 1, characterized in that, The preparation method of the polytetrafluoroethylene-coated boron nitride particles is as follows: by weight, 100 parts of boron nitride particles are dispersed in 300-800 parts of an aqueous polytetrafluoroethylene dispersion, the solid content of the polytetrafluoroethylene dispersion is 30-60 wt.%, and it is treated with an ultrasonic power of 300-1000 W for 15-90 min to form a uniform suspension system, 2.0-5.0 parts of sodium dodecyl sulfate are added as a dispersant and mixed evenly under the condition that the stirring rate is 300-1000 rpm, hydrochloric acid or ammonia water with a concentration of 5-10 wt% is added dropwise to adjust the pH to 2-5, the temperature is raised to 60-100 °C and kept at a constant temperature for reaction for 2-4 h to deposit polytetrafluoroethylene in situ on the particle surface to form a film, after the reaction, the liquid phase and the uncoated polytetrafluoroethylene particles are removed by vacuum filtration, the solid phase is retained and ultrasonically washed 3-5 times with absolute ethanol to remove the surfactant and free ions, then the product is transferred to an oven and dried at 100-150 °C for 3-12 h to obtain a primary coated powder, and then the powder is placed in a tube furnace, nitrogen is introduced for protection, and it is heated to 320-400 °C at a heating rate of 2-10 °C / min for sintering for 1-3 h to densify the polytetrafluoroethylene film layer, and finally, polytetrafluoroethylene-coated boron nitride particles are obtained.

7. A high-performance scratch-resistant, wear-resistant and corrosion-resistant steel-substituting nylon material as described in claim 1, characterized in that, The preparation method of the boron nitride particles is as follows: by weight, 100 parts of hexagonal boron nitride raw material powder with an initial particle size of 5 - 20 μm and a purity of ≥99% is mixed with 500 - 2000 parts of zirconia ball milling media with a diameter of 5 mm. Wet ball milling is carried out using a planetary ball mill with a ball-to-material ratio of 5:1 - 20:1 and a rotation speed of 200 - 600 rpm, and 100 - 500 parts of deionized water and 2 - 5 parts of polyvinylpyrrolidone are added to form a slurry with a solid-liquid ratio of 1:1 - 1:

5. The filling rate of the ball milling tank is controlled to be 50 - 70% and the ball milling time is 10 - 20 h. During the process, the temperature is maintained ≤60°C to avoid the destruction of the boron nitride structure. After ball milling, the ball milling media are removed by centrifugal separation and the boron nitride suspension with a particle size ≤3 μm is retained. Subsequently, the suspension is vacuum dried at 60 - 100°C for 4 - 12 h to remove the dispersion medium, and then subjected to a deagglomeration treatment by a jet mill at a pressure of 0.5 - 1.2 MPa. Finally, the boron nitride particles are obtained by calcining in a nitrogen atmosphere at a heating rate of 5 - 10°C / min to 800 - 1200°C for 1 - 2 h.

8. A high-performance scratch-resistant, wear-resistant and corrosion-resistant steel-substituted nylon material as claimed in claim 1, characterized in that, The average diameter of the polytetrafluoroethylene-coated boron nitride particles is 200 - 800 nm; the thickness of the polytetrafluoroethylene coating layer is 30 - 80 nm.

9. A high-performance scratch-resistant, wear-resistant and corrosion-resistant nylon material substituting steel with plastic as claimed in claim 1, characterized in that, The nylon matrix resin is a mixture of PA6 and PA66 with a mass ratio of (60 - 80):(40 - 20).

10. A high-performance scratch-resistant, wear-resistant and corrosion-resistant nylon material substituting steel with plastic as described in claim 1, characterized in that, The compatibilizer is polyethylene grafted maleic anhydride; The antioxidant is antioxidant 1010; The lubricant is ethylene bisstearamide.

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