Polytetrafluoroethylene-based piston ring based on coupling agent modified multi-effect reinforcing filler and preparation method of polytetrafluoroethylene-based piston ring

Abstract

The invention discloses a polytetrafluoroethylene-based piston ring based on a coupling agent modified multi-effect reinforcing filler and a preparation method of the polytetrafluoroethylene-based piston ring. The polytetrafluoroethylene-based piston ring is prepared from the following raw materials in percentage by mass: 5-20% of the coupling agent modified multi-effect reinforcing filler, 10-30% of a high polymer and the balance of polytetrafluoroethylene. In the preparation raw materials of the piston ring, the polytetrafluoroethylene and the high polymer (chloromethylated polyether-ether-ketone) are used as piston ring matrix components, and the coupling agent modified multi-effect reinforcing filler is used as a reinforcing component; the high polymer and the coupling agent modified multi-effect reinforcing filler are compounded and added in the polytetrafluoroethylene, so that the wear resistance, the high temperature resistance and the mechanical strength of the prepared piston ring are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of polytetrafluoroethylene piston rings, in particular to a polytetrafluoroethylene-based piston ring based on coupling agent modified multi-effect reinforcing filler and a preparation method thereof. BACKGROUND

[0002] An air compressor is a device used to compress gas, commonly used for gas delivery, processing and other operations. Most air compressors are reciprocating piston type. The piston ring is a component used for sealing in an air compressor, and its main function is to seal the gap between the cylinder mirror and the piston to prevent gas from leaking from one side of the compression volume to the other. According to the lubrication method, it can be divided into oil-free air compressor and oil lubricated air compressor. The oil-free air compressor can meet the requirement that the compressed gas cannot contain oil, and also has the advantages of quietness, environmental protection, etc., and has been widely used in many scenes. The piston ring of the oil-free air compressor usually uses a non-metallic material with self-lubricating properties, such as polyether ether ketone, polytetrafluoroethylene, polyimide, etc. The polytetrafluoroethylene-based piston ring has excellent corrosion resistance, high temperature resistance and low friction coefficient, etc., and therefore has been widely used in many high-demand fields, such as the production method of polytetrafluoroethylene piston ring disclosed in patent CN115609824A, the PTFE composite material and the piston ring made of the same disclosed in patent CN108003521A, and the high-strength friction-resistant piston ring and its preparation process disclosed in patent CN116178864A.

[0003] The polytetrafluoroethylene-based piston ring has the advantages of corrosion resistance and low friction coefficient, but it is easy to wear and has poor thermal conductivity, with a thermal conductivity of about 0.21 W / (K·m) to 0.25 W / (K·m), and the heat resistance and strength need to be further improved. Using fillers to modify is an effective method to improve the performance of polytetrafluoroethylene. SiC has low density, high hardness, excellent heat resistance and wear resistance, and is a commonly used reinforcing filler in polymers. Patent CN104387708A discloses a polytetrafluoroethylene piston ring and a preparation method thereof, in which silicon carbide is added to polytetrafluoroethylene as one of the fillers to improve its wear resistance. However, the poor compatibility of inorganic filler SiC with polytetrafluoroethylene and the easy agglomeration of SiC seriously affect its reinforcing effect. Luqin et al. modified SiC with silane coupling agent and then added it to the polytetrafluoroethylene system, which can improve the compatibility of SiC with polytetrafluoroethylene to some extent and improve the reinforcing effect of SiC (Luqin, Yangming, Hechunxia. Coupling modification of nano-silicon carbide / polytetrafluoroethylene-based composite material's friction and wear properties [J]. Plastics, 2008, 37(6):4. DOI: CNKI: SUN: SULA.0.2008-06-009.). However, the single SiC filler has limited effect on the improvement of the comprehensive performance of polytetrafluoroethylene, such as wear resistance and high temperature resistance.

[0004] Therefore, there is a need for improvements in the art to provide a more reliable solution. SUMMARY

[0005] The technical problem solved by the present application is to provide a polytetrafluoroethylene-based piston ring based on coupling agent modified multi-effect enhanced filler and a preparation method thereof to solve the problems in the prior art.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is: a polytetrafluoroethylene-based piston ring based on coupling agent modified multi-effect enhanced filler, the preparation raw materials include the following components by mass fraction: coupling agent modified multi-effect enhanced filler 5-20%, high polymer 10-30%, and the balance is polytetrafluoroethylene; The coupling agent modified multi-effect enhanced filler is prepared by the following steps: S1, grafting Al2O3 and CeO2 on the carboxylated graphene oxide to obtain nanoparticle hybrid graphene oxide; S2, in-situ synthesis of SiC on the nanoparticle hybrid graphene oxide to obtain composite enhanced particles; S3, modifying the composite enhanced particles with a silane coupling agent to obtain coupling agent modified enhanced particles; S4, grafting chloromethylated polyether ether ketone and polyetherimide on the coupling agent modified enhanced particles to obtain coupling agent modified multi-effect enhanced filler.

[0007] Preferably, the high polymer is chloromethylated polyether ether ketone, which is prepared by the following method: dissolving polyether ether ketone powder in 95-98wt% concentrated sulfuric acid at 0~5°C, adding chloromethyl octyl ether, stirring and reacting, after the reaction is completed, pouring the product into an ice water mixture, suction filtering, adding N-methyl pyrrolidone to the washed product, stirring, filtering, pouring the filtrate into deionized water, suction filtering, and drying the solid product to obtain chloromethylated polyether ether ketone.

[0008] Preferably, the chloromethylated polyether ether ketone is prepared by the following method: 0~5°C, dissolving 0.5-2g of polyether ether ketone powder in 50-200mL of 98wt% concentrated sulfuric acid, adding 5-20mL of chloromethyl octyl ether, stirring and reacting for 1-4h, pouring the product into 350-1400mL of an ice water mixture under stirring, suction filtering, adding 10-40mL of N-methyl pyrrolidone to the washed product, stirring for 10-40min, filtering, pouring the filtrate into deionized water, suction filtering, and drying the solid product to obtain chloromethylated polyether ether ketone.

[0009] Preferably, the chloromethylated polyether ether ketone is prepared by the following method: At 0°C, 1g of polyetheretherketone powder was added to 100mL of 98wt% concentrated sulfuric acid and stirred until completely dissolved. Then, 10mL of chloromethyl octyl ether was added and the mixture was stirred for 2h. The product was then poured into 700mL of an ice-water mixture under stirring and filtered. The product was washed with deionized water until neutral and then washed with ethanol. It was then added to 20mL of N-methylpyrrolidone and stirred for 20min. The mixture was filtered (to remove unchloromethylated polyetheretherketone). The filtrate was poured into deionized water and filtered again. The solid product was dried under vacuum at 60°C for 24h to obtain chloromethylated polyetheretherketone.

[0010] Preferably, the coupling agent-modified multi-effect reinforced filler is prepared through the following steps: S1. Grafting Al2O3 and CeO2 onto carboxylated graphene oxide: S1-1. Add graphene oxide to a mixed acid composed of sulfuric acid and nitric acid and heat under reflux to obtain carboxylated graphene oxide. S1-2. Carboxylated graphene oxide, CTAB (hexadecyltrimethylammonium bromide), AlCl3, and Ce(NO3)3 are ultrasonically dispersed in deionized water to obtain solution A. S1-3. Add urea to deionized water and stir to obtain solution B. Add solution B dropwise to solution A. After the addition is complete, stir. Transfer the resulting mixture to a reaction vessel and react at 170-200℃ for 6-24 hours. Centrifuge to separate the precipitate, wash and dry it, and then calcine it at 600-800℃ for 3-8 hours to obtain nanoparticle hybrid graphene oxide. S2. In-situ synthesis of SiC on nanoparticle-hybridized graphene oxide: S2-1. Take silica sol, sucrose, composite reinforcing particles, Fe(NO3)3·9H2O, and deionized water, add them to ethanol, sonicate, stir, dry, and grind to obtain precursor powder. S2-2. Under argon protection, the precursor powder is first kept at 1500-1750℃ for 2-6 hours, then heated at 550-700℃ in air atmosphere for 1-4 hours. After cooling, it is soaked in sulfuric acid, filtered, washed and dried to obtain composite reinforced particles. S3. Modify the composite reinforcing particles using a silane coupling agent: S3-1. Add acid to an alcohol-water solution composed of ethanol and deionized water to adjust the pH to 4.5-5.5, then add silane coupling agent to obtain a coupling agent solution. S3-2. Disperse the composite reinforcing particles in ethanol, add the coupling agent solution, stir at 50-80℃ for 3-12h, filter, wash and dry to obtain coupling agent modified reinforcing particles. S4. Grafting chloromethylated polyetheretherketone and polyetherimide onto coupling agent modified reinforced particles: Chloromethylated polyether ether ketone and polyether imide were added to DMAC (dimethylacetamide) and heated and stirred to obtain a polymer solution. The coupling agent-modified reinforcing particles were dispersed in DMAC to obtain a particle dispersion. The particle dispersion was added to the polymer solution, ultrasonically dispersed, and stirred at 70-90℃ for 4-16 hours. The temperature was then raised to 165-175℃ to evaporate the solvent, dry the product, grind it, and obtain the coupling agent-modified multi-effect reinforcing filler.

[0011] Preferably, step S1 specifically includes: S1-1. Add graphene oxide to a mixed acid consisting of 95wt% sulfuric acid and 60wt% nitric acid in a volume ratio of 2:1, heat under reflux at 60-100℃ for 3-12 hours, filter, wash and dry to obtain carboxylated graphene oxide. S1-2, Add 0.5-2g carboxylated graphene oxide, 0.07-0.3g CTAB, 0.25-1g AlCl3, and 0.05-0.22g Ce(NO3)3 to 50-200mL of deionized water and sonicate for 1-4h to obtain solution A; S1-3. Add 0.5-2g of urea to 5-20mL of deionized water and stir for 5-30min to obtain solution B. Add solution B dropwise to solution A while stirring. After the addition is complete, stir for 3-12h. Transfer the resulting mixture to a reaction vessel and react at 170-200℃ for 6-24h. Cool down, centrifuge, wash and dry the precipitate, grind it into powder, and then calcine it at 600-800℃ for 3-8h to obtain nanoparticle hybrid graphene oxide.

[0012] Preferably, step S2 specifically includes: S2-1. Take 5-20g of silica sol with a SiO2 content of 20-30wt%, 3.5-15g of sucrose, 1-4g of composite reinforcing particles, 0.2-0.8g of Fe(NO3)3·9H2O, and 15-60mL of deionized water and add them to 35-140mL of ethanol. Sonicate for 1-4h, stir at 1500-7000rpm for 2-8h, dry at 100-150℃ for 10-48h, and grind to obtain precursor powder. S2-2. Under argon protection, the precursor powder is first kept at 1500-1600℃ for 0.5-2h, then heated to 1600-1750℃ and kept at that temperature for 1-3h. The resulting powder is then heated at 550-700℃ in air for 1-4h. After cooling, it is soaked in 10-30wt% sulfuric acid for 15-60min, filtered, washed, and dried to obtain composite reinforcing particles.

[0013] Preferably, step S3 specifically includes: S3-1. Add acetic acid to an alcohol-water solution composed of ethanol and deionized water in a volume ratio of 8:2, adjust the pH to 4.5-5.5, add silane coupling agent to make the concentration of silane coupling agent 1-5wt%, and obtain a coupling agent solution. S3-2. Take 1.5-6g of composite reinforcing particles and add them to 50-200mL of ethanol. Disperse them by ultrasonication for 1.5-6h. Add 5-20mL of coupling agent solution and stir at 50-80℃ for 3-12h. Filter, wash and dry to obtain coupling agent modified reinforcing particles.

[0014] Preferably, the silane coupling agent is selected from at least one of KH-550 (γ-aminopropyltriethoxysilane), KH-560 (γ-glycidoxypropyltrimethoxysilane), KH-570 (γ-methacryloyloxypropyltrimethoxysilane), and A-151 (vinyltriethoxysilane).

[0015] Preferably, step S4 specifically includes: Take 2.5-10g of chloromethylated polyether ether ketone and 1.5-6g of polyetherimide and add them to 75-300mL of DMAC. Stir at 70-90℃ for 5-20min to obtain a polymer solution. Add 2-8g of coupling agent modified reinforcing particles to 25-100mL of DMAC and ultrasonically disperse for 0.5-2h to obtain a particle dispersion. Add the particle dispersion to the polymer solution with stirring and ultrasonically disperse for 45-180min. Then stir and react at 70-90℃ for 4-16h. Raise the temperature to 165-175℃ to evaporate the solvent. Dry the product and grind it to obtain the coupling agent modified multi-effect reinforcing filler.

[0016] Preferably, the coupling agent-modified multi-effect reinforced filler is prepared through the following steps: S1. Grafting Al2O3 and CeO2 onto carboxylated graphene oxide: S1-1. Add graphene oxide to a mixed acid consisting of 95wt% sulfuric acid and 60wt% nitric acid in a volume ratio of 2:1, heat under reflux at 80°C for 6 hours, filter, wash and dry to obtain carboxylated graphene oxide. S1-2, Add 1g of carboxylated graphene oxide, 0.15g of CTAB, 0.532g of AlCl3, and 0.11g of Ce(NO3)3 to 100mL of deionized water and sonicate for 2h to obtain solution A; S1-3. Add 1g of urea to 10mL of deionized water and stir for 10min to obtain solution B. Add solution B dropwise to solution A while stirring. After the addition is complete, stir for 6h. Transfer the resulting mixture to a reaction vessel and react at 185℃ for 12h. Cool down, centrifuge to separate, wash and dry the precipitate, grind it into powder, and then calcine at 700℃ for 5h to obtain nanoparticle hybrid graphene oxide. S2. In-situ synthesis of SiC on nanoparticle-hybridized graphene oxide: S2-1. Take 10g of silica sol with a SiO2 content of 25wt%, 7.5g of sucrose, 2g of composite reinforcing particles, 0.4g of Fe(NO3)3·9H2O, and 30mL of deionized water and add them to 70mL of ethanol. Sonicate for 2h, stir at 3000rpm for 4h, dry at 120℃ for 20h, and grind to obtain precursor powder. S2-2. Under argon protection, the precursor powder was first kept at 1500℃ for 1 hour, then heated to 1650℃ and kept for 1.5 hours. The resulting powder was then heated at 650℃ in air for 2 hours. After cooling, it was soaked in 20wt% sulfuric acid for 45 minutes (to remove Al2O3 that did not form the mullite phase). The powder was then filtered, washed, and dried to obtain composite reinforced particles. S3. Modify the composite reinforcing particles using a silane coupling agent: S3-1. Add acetic acid to an alcohol-water solution composed of ethanol and deionized water in a volume ratio of 8:2, adjust the pH to 4.5-5.5, add silane coupling agent KH-570 to make the concentration of silane coupling agent 2wt%, and obtain a coupling agent solution. S3-2. Take 3g of composite reinforcing particles and add them to 100mL of ethanol. Disperse them by ultrasonication for 3h. Add 10mL of coupling agent solution and stir at 75℃ for 6h. Filter, wash and dry to obtain coupling agent modified reinforcing particles. S4. Grafting chloromethylated polyetheretherketone and polyetherimide onto coupling agent modified reinforced particles: Take 5g of chloromethylated polyether ether ketone (i.e., the above polymer) and 3g of polyetherimide and add them to 150mL of DMAC. Stir at 80℃ for 10min to obtain a polymer solution. Add 4g of coupling agent modified reinforcing particles to 50mL of DMAC and sonicate for 1h to obtain a particle dispersion. Add the particle dispersion to the polymer solution under stirring and sonicate for 90min. Then stir and react at 85℃ for 8h. Raise the temperature to 170℃ to evaporate the solvent. Dry the product and grind it to obtain the coupling agent modified multi-effect reinforcing filler.

[0017] Invention Mechanism

[0018] Polytetrafluoroethylene (PTFE) piston rings have advantages such as corrosion resistance and low coefficient of friction, but they are prone to wear, and their heat resistance and strength need further improvement. In this invention, PTFE and a polymer (chloromethylated polyetheretherketone) are used as the piston ring matrix components, and coupling agent modified multi-effect reinforcing filler is used as the reinforcing component. The compound addition of polymer and coupling agent modified multi-effect reinforcing filler to PTFE can significantly improve the wear resistance, high temperature resistance and mechanical strength of the prepared piston ring.

[0019] The addition of polyetheretherketone (PEEK) can significantly improve the wear resistance and high-temperature resistance of polytetrafluoroethylene (PTFE), while also increasing its tensile strength and rigidity. The π-π conjugated structure in PEEK can form strong π-π stacking with the abundant π-π conjugated structures on the graphene oxide in the coupling agent-modified multi-effect reinforcing filler, thereby helping to improve the bonding strength between the coupling agent-modified multi-effect reinforcing filler and the piston ring matrix components. Furthermore, in this invention, by chloromethylating polyetheretherketone (PEEK), active groups are introduced, which can improve the connection strength between PEEK and coupling agent-modified multi-functional reinforcing filler, thus improving the overall performance. In addition, the solubility of the treated chloromethylated PEEK is significantly improved, and it can be well dissolved in solvents such as DMAC. Therefore, the composite grafting and coating of coupling agent-modified reinforcing particles with chloromethylated PEEK and polyetherimide can be achieved by a simple solvent evaporation method, thereby improving the compatibility between coupling agent-modified reinforcing particles and piston ring matrix components (polytetrafluoroethylene and polymers).

[0020] The coupling agent-modified multi-effect reinforcing filler prepared in this invention is a composite material consisting of graphene oxide and in-situ grown nano-SiC as the main fillers, mullite as a hybrid component, and silane coupling agent, chloromethylated polyether ether ketone, and polyetherimide as surface modifying components. It can significantly improve the wear resistance, mechanical strength, toughness, heat resistance, and thermal conductivity of the piston ring matrix. Furthermore, it exhibits good compatibility with the piston ring matrix components (polytetrafluoroethylene and polymers), enabling uniform dispersion of the main filler and overcoming the application defects of inorganic fillers such as graphene oxide and nano-SiC in organic systems, which are prone to agglomeration and difficult to disperse. The preparation principle and mechanism of action of the coupling agent-modified multi-effect reinforcing filler are explained in more detail below to facilitate understanding of this invention.

[0021] 1. First, graphene oxide is acidified by a mixed acid composed of sulfuric acid and nitric acid, which forms a large number of carboxyl groups on the surface of graphene oxide, creating favorable conditions for the subsequent in-situ grafting of Al2O3 and CeO2. Then, using CTAB as a surfactant, urea as a precipitant, and AlCl3 and 0.11g Ce(NO3)3 as aluminum and cerium sources respectively, a large number of Al2O3 and CeO2 nanoparticles were uniformly grafted onto carboxylated graphene oxide through hydrothermal reaction combined with high-temperature calcination, resulting in nanoparticle hybrid graphene oxide; after mixing the raw materials, Al... 3+ Ce 4+ Through coordination with carboxyl groups and electrostatic adsorption, a large number of carboxylated graphene oxide nanoparticles can be attached to the surface, thereby promoting the uniform and abundant grafting of Al2O3 and CeO2 nanoparticles onto its surface. 2. Next, using silica sol as the silicon source, sucrose as the carbon source, composite reinforcing particles as the carrier, and Fe(NO3)3·9H2O as the catalyst, SiC was synthesized in situ on the surface of graphene oxide via a low-temperature carbothermal reduction method. The carrier effect of graphene oxide enabled the synthesized SiC to have a more uniform nanoscale size and achieve uniform distribution, and it also had a higher bonding strength with graphene oxide. Among them, a portion of SiO2, which is the silicon source, can react with Al2O3 grafted on the surface of graphene oxide to form a mullite phase, which can enhance the bonding strength between nano-SiC particles and between them and graphene oxide. Meanwhile, the generated mullite can also improve the tribological properties, enhance the mechanical properties, and improve the thermal stability of polytetrafluoroethylene (Li Cui, Sun Tao, Shi Guojun, Yuan Yue, Zhang Chenkai. Mullite-filled polytetrafluoroethylene composites and their tribological properties [J]. Journal of Materials Research, 2016, 30(6):11.DOI:CNKI:SUN:CYJB.0.2016-06-004.) In this process, CeO2 grafted onto graphene oxide can promote the formation of mullite by lowering the formation temperature and improving the high-temperature toughness of mullite (Liu Weiyue, Liu Meihua. The effect of cerium oxide on improving the properties of ZTM ceramics [J]. Bulletin of the Chinese Ceramic Society, 1996, 15(3):4.DOI:CNKI:SUN:GSYT.0.1996-03-001.), which also enhances the wear resistance of piston rings at high temperatures.

[0022] SiC has low density, high hardness, and excellent heat resistance and wear resistance. Its addition to polytetrafluoroethylene (PTFE) can significantly improve the wear resistance and strength of PTFE (Lu Qin, Yang Ming, He Chunxia. Tribological properties of coupling modified nano-silicon carbide / polytetrafluoroethylene composites [J]. Plastics, 2008, 37(6):4.DOI:CNKI:SUN:SULA.0.2008-06-009.), and SiC can also improve the thermal conductivity of PTFE.

[0023] Graphene oxide can play the following reinforcing role in polytetrafluoroethylene: (1) The sheet structure of graphene oxide can be embedded in the gaps between the molecular chains of polytetrafluoroethylene, enhancing the creep resistance; (2) Graphene oxide can improve the wear resistance of PTFE and maintain a low coefficient of friction (Wang Yonghu, Wang Lingjuan, Song Liming, et al. Graphene oxide-polytetrafluoroethylene nanocomposite materials and their properties [J]. Chemical Production and Technology, 2014(2):12-14.DOI:10.3969 / j.issn.1006-6829.2014.02.002.); (3) Graphene oxide can significantly improve the thermal conductivity of polytetrafluoroethylene, thereby avoiding the phenomenon of high-temperature softening of piston rings due to heat accumulation through timely heat dissipation, and improving the adaptability of piston rings to high-temperature environments.

[0024] In this invention, a composite of graphene oxide and SiC was obtained by in-situ growth of SiC on graphene oxide. In this composite, SiC and graphene oxide can achieve more uniform mixing and tighter bonding. SiC has a more uniform nanoscale size and can be uniformly distributed on the graphene oxide. SiC also acts as a connecting node, enabling the two-dimensional graphene oxide structure to interweave and form a three-dimensional network structure. This reduces the curling of graphene oxide and further enhances the overall strength by forming a network structure. It also improves thermal conductivity by providing a three-dimensional thermal conduction path. Through the organic combination of SiC and graphene oxide, the reinforcing effects of each are further enhanced. Furthermore, the composite also contains mullite, which can improve bonding strength, tribological properties, and thermal stability, as well as CeO2, which also improves high-temperature wear resistance. These components can work with graphene oxide and SiC to improve the overall performance of the prepared polytetrafluoroethylene piston ring.

[0025] 3. Then, through simple impregnation and mixing, the silane coupling agent was used to modify the composite reinforcing particles. This modification can improve the dispersibility of the composite reinforcing particles, improve their compatibility with organic matter, and create favorable conditions for subsequent polymer grafting.

[0026] 4. Finally, a simple solvent evaporation method was used to graft chloromethylated polyetheretherketone (PEEK) and polyetherimide onto the coupling agent-modified reinforcing particles. This significantly improved the compatibility between the resulting coupling agent-modified reinforcing particles and the piston ring matrix components. PEEK has poor solubility, typically only soluble in solvents such as concentrated sulfuric acid, limiting its application in coating inorganic particles via solvent evaporation. In this invention, chloromethylation of PEEK significantly improves its solubility, allowing it to be dissolved together with polyetherimide in DMAC (dimethylacetamide) solvent. Then, the composite coating modification of chloromethylated PEEK and polyetherimide onto the coupling agent-modified reinforcing particles can be achieved through solvent evaporation. The piston ring matrix component contains polytetrafluoroethylene (PTFE) and chloromethylated polyetheretherketone (PEI). Modification using a composite coating of chloromethylated PEI and polyetherimide (PEI) can better improve the compatibility between the coupling agent-modified multi-effect reinforcing filler and the piston ring matrix component, promoting its uniform dispersion and bonding strength within the piston ring matrix component. Polyetherimide and PEI have good compatibility; the grafting coating of polyetherimide significantly improves the compatibility between the coupling agent-modified multi-effect reinforcing filler and the piston ring matrix component. Furthermore, it can enhance heat resistance, improve mechanical properties, and improve processing characteristics (the introduction of PEI can improve the melt strength and flowability of PTFE).

[0027] The present invention also provides a method for preparing a polytetrafluoroethylene piston ring based on a coupling agent-modified multi-effect reinforcing filler as described above, comprising the following steps: Step 1: After crushing and drying the polymer and polytetrafluoroethylene, mix them with the coupling agent-modified multi-effect reinforcing filler to obtain the raw material mixture; Step 2: Add the raw material mixture into the mold and press it into shape to obtain a piston ring blank; Step 3: Sinter the piston ring blank, cool it, and machine it to obtain the finished piston ring.

[0028] Preferably, in step two, the pressing pressure is 15-30 MPa and the pressing time is 10-60 s.

[0029] Preferably, in step three, the sintering process is as follows: holding at 250-280℃ for 2-4 hours; raising the temperature to 340-420℃ and holding for 0.5-1 hours; lowering the temperature to 160-250℃ and holding for 1-3 hours.

[0030] The beneficial effects of this invention are: This invention provides a polytetrafluoroethylene piston ring based on a coupling agent-modified multi-effect reinforcing filler and its preparation method. In the preparation of the piston ring of this invention, polytetrafluoroethylene and a polymer (chloromethylated polyether ether ketone) are used as the piston ring matrix components, and a coupling agent-modified multi-effect reinforcing filler is used as the reinforcing component. The compound addition of the polymer and the coupling agent-modified multi-effect reinforcing filler to polytetrafluoroethylene significantly improves the wear resistance, high temperature resistance and mechanical strength of the prepared piston ring.

[0031] The coupling agent modified multi-effect reinforcing filler prepared in this invention is a composite system with graphene oxide and in-situ grown nano-SiC as the main filler, mullite as the hybrid component, and silane coupling agent, chloromethylated polyether ether ketone and polyetherimide as surface modifying components. It can significantly improve the wear resistance, mechanical strength, toughness, heat resistance and thermal conductivity of the piston ring matrix. Moreover, it has good compatibility with the piston ring matrix components (polytetrafluoroethylene and polymers), and can achieve uniform dispersion of the main filler. It overcomes the application defects of inorganic fillers such as graphene oxide and nano-SiC in organic systems, which are prone to agglomeration and difficult to disperse.

[0032] In this invention, a composite of graphene oxide and SiC was obtained by in-situ growth of SiC on graphene oxide. In this composite, SiC and graphene oxide achieve more uniform mixing and tighter bonding. SiC has a more uniform nanoscale size and can be evenly distributed on the graphene oxide. SiC also acts as a connecting node, enabling the two-dimensional graphene oxide to interweave and form a three-dimensional network structure. This reduces the curling of the graphene oxide and further enhances the overall strength and thermal conductivity through the network structure. The organic synergy between SiC and graphene oxide further improves their respective reinforcing effects. Furthermore, the composite also contains mullite, which improves bonding strength, tribological properties, and thermal stability, as well as CeO2, which improves high-temperature wear resistance. These components can work with graphene oxide and SiC to improve the overall performance of the prepared polytetrafluoroethylene piston rings. Attached Figure Description

[0033] Figure 1 XRD pattern of nanoparticle-hybridized graphene oxide prepared in Example 1; Figure 2 The XRD pattern of the composite reinforcing particles prepared in Example 1; Figure 3 The wear resistance test results are for the examples and comparative examples; Figure 4 The tensile strength test results are for the examples and comparative examples; Figure 5 The hardness test results are for the examples and comparative examples.

[0034] Figure 6 The thermal conductivity test results are for the examples and comparative examples. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0036] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0037] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available. For examples where specific conditions are not specified, conventional conditions or conditions recommended by the manufacturer are followed. For reagents or instruments whose manufacturers are not specified, they are all commercially available products.

[0038] The main raw materials involved in the examples and comparative examples are described below: Polytetrafluoroethylene, grade PTFE 8AX, Shanghai Shengyiyuan Plastics Co., Ltd.; Polyetheretherketone, model KETRON HPV PEEK (Mitsubishi Chemical), purchased from Shanghai Huifei Chemical Co., Ltd.; Chloromethyl octyl ether, Shanghai Maclean Biochemical Technology Co., Ltd.; N-Methylpyrrolidone, Shanghai Maclean Biochemical Technology Co., Ltd.; Graphene oxide, with flakes ranging from 0.5 to 3 μm in size and 0.55 to 1.2 nm in thickness, from Shanghai Aladdin Biochemical Technology Co., Ltd. Silica sol, SiO2 content 25wt%, particle size 20-30nm, model ZTL-JN, Yangzhou Zhongtianli New Material Co., Ltd. CTAB (hexadecyltrimethylammonium bromide), Jiangsu Runfeng Synthetic Technology Co., Ltd. Silane coupling agent KH-570, Shanghai Aladdin Biochemical Technology Co., Ltd.; Polyetherimide, brand: Saudi Basic, grade: 1000R, purchased from Suzhou Xiaoxinhe Plastics Co., Ltd.; DMAC (N,N-dimethylacetamide), Shanghai Aladdin Biochemical Technology Co., Ltd. Nano SiC, 100nm particle size, Shanghai Naio Nanotechnology Co., Ltd. Example 1

[0039] A polytetrafluoroethylene piston ring based on coupling agent modified multi-effect reinforcing filler, the raw materials for its preparation include the following components by mass fraction: 12% coupling agent modified multi-effect reinforcing filler, 17% polymer, and the balance being polytetrafluoroethylene.

[0040] The method for preparing this piston ring includes the following steps: Step 1: Crush the polymer and polytetrafluoroethylene to below 600 mesh, dry them at 150℃ for 4 hours, and then mix them with the coupling agent-modified multi-effect reinforcing filler to obtain the raw material mixture; Step 2: Add the raw material mixture into the mold and press it to form a piston ring blank; the pressing pressure is 18MPa and the pressing time is 45s. Step 3: Sinter the piston ring blank, cool it, and machine it to obtain the finished piston ring. The sintering process is as follows: hold at 270℃ for 4 hours; raise the temperature to 380℃ and hold for 0.5 hours; lower the temperature to 220℃ and hold for 3 hours.

[0041] The polymer is chloromethylated polyetheretherketone, which is prepared by the following method: At 0°C, 1g of polyetheretherketone powder was added to 100mL of 98wt% concentrated sulfuric acid and stirred until completely dissolved. Then, 10mL of chloromethyl octyl ether was added and the mixture was stirred for 2h. The product was then poured into 700mL of an ice-water mixture under stirring and filtered. The product was washed with deionized water until neutral and then washed with ethanol. It was then added to 20mL of N-methylpyrrolidone and stirred for 20min. The mixture was filtered, and the filtrate was poured into deionized water and filtered again. The solid product was dried under vacuum at 60°C for 24h to obtain chloromethylated polyetheretherketone.

[0042] The coupling agent-modified multi-effect reinforced filler is prepared through the following steps: S1. Grafting Al2O3 and CeO2 onto carboxylated graphene oxide yields nanoparticle-hybridized graphene oxide: S1-1. Add 5g of graphene oxide to a mixed acid consisting of 100mL of 95wt% concentrated sulfuric acid and 50mL of 60wt% concentrated nitric acid, heat and reflux at 80℃ for 6h, filter, wash with deionized water until neutral, and vacuum dry at 90℃ for 12h to obtain carboxylated graphene oxide. S1-2, 1g of carboxylated graphene oxide, 0.25g of CTAB, 0.532g of AlCl3, and 0.11g of Ce(NO3)3 were added to 100mL of deionized water and ultrasonically dispersed for 2h to obtain solution A; S1-3. Add 1g of urea to 10ml of deionized water and stir for 10min to obtain solution B. Add solution B dropwise to solution A while stirring. After the addition is complete, continue stirring for 6h. Transfer the resulting mixture to a reaction vessel and react at 185℃ for 12h. Cool to room temperature, centrifuge to separate the precipitate, wash with deionized water, dry at 90℃ for 8h, grind into powder, and then calcine at 700℃ for 5h to obtain nanoparticle hybrid graphene oxide.

[0043] Reference Figure 1 The image shows the XRD pattern of the nanoparticle hybrid graphene oxide prepared in this embodiment, indicating that Al2O3 and CeO2 were successfully grafted onto carboxylated graphene oxide, and nanoparticle hybrid graphene oxide was synthesized.

[0044] S2. In-situ synthesis of SiC on nanoparticle-hybridized graphene oxide yields composite reinforcing particles: S2-1. Take 10g of silica sol with a SiO2 content of 25wt% (SiO2 particle size 20-30nm), 7.5g of sucrose, 2g of composite reinforcing particles, 0.4g of Fe(NO3)3·9H2O, and 30mL of deionized water and add them to 70mL of ethanol. Sonicate for 2h, stir at 3000rpm for 4h, dry at 120℃ for 20h, and grind to obtain precursor powder. S2-2. Under argon protection, the precursor powder was heated to 1500℃ at 25℃ / min and held for 1h, then heated to 1650℃ at 15℃ / min and held for 1.5h, and cooled to room temperature in the furnace. The resulting powder was heated to 650℃ in air atmosphere for 2h, cooled to room temperature, and then soaked in 20wt% sulfuric acid for 45min. After filtration, it was washed with deionized water until neutral and dried under vacuum at 100℃ for 24h to obtain composite reinforced particles.

[0045] Reference Figure 2 The image shows the XRD pattern of the composite reinforcing particles prepared in this embodiment (GO represents graphene oxide, and Mullite represents mullite). The appearance of the diffraction characteristic peaks of SiC and mullite indicates that SiC was successfully synthesized in nanoparticle-hybridized graphene oxide and a mullite phase was formed, indicating that the composite reinforcing particles were successfully synthesized.

[0046] S3. Modify the composite reinforcing particles with a silane coupling agent to obtain coupling agent-modified reinforcing particles: S3-1. Add acetic acid to an alcohol-water solution composed of ethanol and deionized water in a volume ratio of 8:2, adjust the pH to 5, add silane coupling agent KH-570 to make the concentration of silane coupling agent 2wt%, and obtain a coupling agent solution. S3-2. Take 3g of composite reinforcing particles and add them to 100mL of ethanol. Disperse them by ultrasonication for 3h, then add 10mL of coupling agent solution, stir at 75℃ for 6h, filter, wash the solid product with ethanol, and dry it under vacuum at 90℃ for 12h to obtain coupling agent modified reinforcing particles.

[0047] S4. Grafting chloromethylated polyetheretherketone and polyetherimide onto coupling agent-modified reinforcing particles yields coupling agent-modified multi-functional reinforcing filler: Take 5g of chloromethylated polyether ether ketone (i.e., the above polymer) and 3g of polyetherimide and add them to 150mL of DMAC. Stir at 80℃ for 10min to obtain a polymer solution. Add 4g of coupling agent modified reinforcing particles to 50mL of DMAC and sonicate for 1h to obtain a particle dispersion. Add the particle dispersion to the polymer solution under stirring and sonicate for 90min. Then stir and react at 85℃ for 8h. Raise the temperature to 170℃ to evaporate the solvent. Vacuum dry the product at 90℃ for 12h and grind it to obtain the coupling agent modified multi-effect reinforcing filler. Example 2

[0048] A polytetrafluoroethylene piston ring based on coupling agent modified multi-effect reinforcing filler, the raw materials for its preparation include the following components by mass fraction: 11% coupling agent modified multi-effect reinforcing filler, 18% polymer, and the balance being polytetrafluoroethylene.

[0049] The method for preparing this piston ring includes the following steps: Step 1: Crush the polymer and polytetrafluoroethylene to below 600 mesh, dry them at 150℃ for 4 hours, and then mix them with the coupling agent-modified multi-effect reinforcing filler to obtain the raw material mixture; Step 2: Add the raw material mixture into the mold and press it to form a piston ring blank; the pressing pressure is 15MPa and the pressing time is 60s. Step 3: Sinter the piston ring blank, cool it, and machine it to obtain the finished piston ring. The sintering process is as follows: hold at 280℃ for 3 hours; raise the temperature to 370℃ and hold for 0.5 hours; lower the temperature to 220℃ and hold for 4 hours.

[0050] The polymer is chloromethylated polyetheretherketone, which is prepared by the following method: At 0°C, 1g of polyetheretherketone powder was added to 100mL of 98wt% concentrated sulfuric acid and stirred until completely dissolved. Then, 10mL of chloromethyl octyl ether was added and the mixture was stirred for 2h. The product was then poured into 700mL of an ice-water mixture under stirring and filtered. The product was washed with deionized water until neutral and then washed with ethanol. It was then added to 20mL of N-methylpyrrolidone and stirred for 20min. The mixture was filtered, and the filtrate was poured into deionized water and filtered again. The solid product was dried under vacuum at 60°C for 24h to obtain chloromethylated polyetheretherketone.

[0051] The preparation method of the coupling agent modified multi-effect reinforced filler is the same as that in Example 1. Example 3

[0052] A polytetrafluoroethylene piston ring based on coupling agent modified multi-effect reinforcing filler, the raw materials for its preparation include the following components by mass fraction: 12% coupling agent modified multi-effect reinforcing filler, 17% polymer, and the balance being polytetrafluoroethylene.

[0053] The method for preparing this piston ring includes the following steps: Step 1: Crush the polymer and polytetrafluoroethylene to below 600 mesh, dry them at 150℃ for 4 hours, and then mix them with the coupling agent-modified multi-effect reinforcing filler to obtain the raw material mixture; Step 2: Add the raw material mixture into the mold and press it to form a piston ring blank; the pressing pressure is 18MPa and the pressing time is 45s. Step 3: Sinter the piston ring blank, cool it, and machine it to obtain the finished piston ring. The sintering process is as follows: hold at 270℃ for 4 hours; raise the temperature to 380℃ and hold for 0.5 hours; lower the temperature to 220℃ and hold for 3 hours.

[0054] The polymer is chloromethylated polyether ether ketone, and its preparation method is the same as in Example 1.

[0055] The coupling agent-modified multi-effect reinforced filler is prepared through the following steps: S1. Grafting Al2O3 and CeO2 onto carboxylated graphene oxide yields nanoparticle-hybridized graphene oxide: S1-1. Add 5g of graphene oxide to a mixed acid consisting of 100mL of 95wt% concentrated sulfuric acid and 50mL of 60wt% concentrated nitric acid, heat and reflux at 80℃ for 6h, filter, wash with deionized water until neutral, and vacuum dry at 90℃ for 12h to obtain carboxylated graphene oxide. S1-2, 1.2g of carboxylated graphene oxide, 0.25g of CTAB, 0.532g of AlCl3, and 0.11g of Ce(NO3)3 were added to 100mL of deionized water and ultrasonically dispersed for 2h to obtain solution A; S1-3. Add 1g of urea to 10ml of deionized water and stir for 10min to obtain solution B. Add solution B dropwise to solution A while stirring. After the addition is complete, continue stirring for 6h. Transfer the resulting mixture to a reaction vessel and react at 185℃ for 12h. Cool to room temperature, centrifuge to separate the precipitate, wash with deionized water, dry at 90℃ for 8h, grind into powder, and then calcine at 700℃ for 5h to obtain nanoparticle hybrid graphene oxide. S2. In-situ synthesis of SiC on nanoparticle-hybridized graphene oxide yields composite reinforcing particles: S2-1. Take 10g of silica sol with a SiO2 content of 25wt% (SiO2 particle size 20-30nm), 7.5g of sucrose, 2g of composite reinforcing particles, 0.35g of Fe(NO3)3·9H2O, and 30mL of deionized water and add them to 70mL of ethanol. Sonicate for 2h, stir at 3000rpm for 4h, dry at 120℃ for 20h, and grind to obtain precursor powder. S2-2. Under argon protection, the precursor powder was heated to 1500℃ at 25℃ / min and held for 1h, then heated to 1650℃ at 15℃ / min and held for 1.5h, and cooled to room temperature in the furnace. The resulting powder was heated to 650℃ in air atmosphere for 2h, cooled to room temperature, and then soaked in 20wt% sulfuric acid for 45min. After filtration, it was washed with deionized water until neutral and dried under vacuum at 100℃ for 24h to obtain composite reinforced particles.

[0056] S3. Modify the composite reinforcing particles with a silane coupling agent to obtain coupling agent-modified reinforcing particles: S3-1. Add acetic acid to an alcohol-water solution composed of ethanol and deionized water in a volume ratio of 8:2, adjust the pH to 5, add silane coupling agent KH-570 to make the concentration of silane coupling agent 2wt%, and obtain a coupling agent solution. S3-2. Take 3g of composite reinforcing particles and add them to 100mL of ethanol. Disperse them by ultrasonication for 3h. Then add 10mL of coupling agent solution and stir at 70℃ for 6h. Filter the mixture and wash the solid product with ethanol. Dry it under vacuum at 90℃ for 12h to obtain coupling agent modified reinforcing particles. S4. Grafting chloromethylated polyetheretherketone and polyetherimide onto coupling agent-modified reinforcing particles yields coupling agent-modified multi-functional reinforcing filler: 4.5g of chloromethylated polyether ether ketone and 3.5g of polyetherimide were added to 150mL of DMAC and stirred at 80℃ for 10min to obtain a polymer solution. 4g of coupling agent-modified reinforcing particles were added to 50mL of DMAC and ultrasonically dispersed for 1h to obtain a particle dispersion. The particle dispersion was added to the polymer solution under stirring and ultrasonically dispersed for 90min. The mixture was then stirred at 85℃ for 8h, heated to 170℃ to evaporate the solvent, and the product was vacuum dried at 90℃ for 12h. After grinding, the coupling agent-modified multi-effect reinforcing filler was obtained.

[0057] Comparative Example 1

[0058] The only difference between this example and Example 1 is that AlCl3 is not added in step S1-2 of preparing the coupling agent modified multi-effect reinforcing filler in this example.

[0059] Comparative Example 2

[0060] The only difference between this example and Example 1 is that Ce(NO3)3 is not added in step S1-2 of preparing the coupling agent modified multi-effect reinforcing filler in this example.

[0061] Comparative Example 3

[0062] The only difference between this example and Example 1 is that the method for preparing the coupling agent-modified multi-effect reinforced filler in this example is as follows: S1. Grafting Al2O3 and CeO2 onto carboxylated graphene oxide to obtain nanoparticle hybrid graphene oxide, the specific steps are the same as in Example 1; S2. SiC is synthesized in situ on nanoparticle-hybridized graphene oxide to obtain composite reinforced particles. The specific steps are the same as in Example 1. S3. Grafting chloromethylated polyetheretherketone and polyetherimide onto the composite reinforcing particles yields coupling agent-modified multi-functional reinforcing filler: 5g of chloromethylated polyether ether ketone and 3g of polyetherimide were added to 150mL of DMAC and stirred at 80℃ for 10min to obtain a polymer solution. 4g of composite reinforcing particles were added to 50mL of DMAC and ultrasonically dispersed for 1h to obtain a particle dispersion. The particle dispersion was added to the polymer solution under stirring and ultrasonically dispersed for 90min. The mixture was then stirred at 85℃ for 8h, heated to 170℃ to evaporate the solvent, and the product was vacuum dried at 90℃ for 12h. After grinding, the coupling agent modified multi-effect reinforcing filler was obtained.

[0063] Comparative Example 4

[0064] The only difference between this example and Example 1 is that this example uses the coupling agent modified reinforcing particles prepared in step S3 of Example 1 as the coupling agent modified multi-effect reinforcing filler.

[0065] Comparative Example 5

[0066] The only difference between this example and Example 1 is that step S4 in preparing the coupling agent modified multi-effect reinforced filler in this example is as follows: Add 8g of polyetherimide to 150mL of DMAC and stir at 80℃ for 10min to obtain a polymer solution; add 4g of coupling agent modified reinforcing particles to 50mL of DMAC and sonicate for 1h to obtain a particle dispersion; add the particle dispersion to the polymer solution under stirring and sonicate for 90min, then stir and react at 85℃ for 8h, raise the temperature to 170℃ to evaporate the solvent, vacuum dry the product at 90℃ for 12h, grind, and obtain the coupling agent modified multi-effect reinforcing filler.

[0067] Comparative Example 6

[0068] The only difference between this example and Example 1 is that the polymer in this example is polyetheretherketone, and step S4 in preparing the coupling agent-modified multi-functional reinforcing filler is as follows: Add 8g of polyetherimide to 150mL of DMAC and stir at 80℃ for 10min to obtain a polymer solution; add 4g of coupling agent modified reinforcing particles to 50mL of DMAC and sonicate for 1h to obtain a particle dispersion; add the particle dispersion to the polymer solution under stirring and sonicate for 90min, then stir and react at 85℃ for 8h, raise the temperature to 170℃ to evaporate the solvent, vacuum dry the product at 90℃ for 12h, grind, and obtain the coupling agent modified multi-effect reinforcing filler.

[0069] Comparative Example 7 A polytetrafluoroethylene piston ring based on a coupling agent-modified multi-effect reinforcing filler comprises the following components by mass fraction: 3% nano-SiC, 5% nanoparticle hybrid graphene oxide, 21% polymer, and the balance being polytetrafluoroethylene.

[0070] The method for preparing this piston ring includes the following steps: Step 1: Pulverize the polymer and polytetrafluoroethylene to below 600 mesh, dry them at 150°C for 4 hours, and then mix them with nano-SiC and nanoparticle hybrid graphene oxide to obtain a raw material mixture. Step 2: Add the raw material mixture into the mold and press it to form a piston ring blank; the pressing pressure is 18MPa and the pressing time is 45s. Step 3: Sinter the piston ring blank, cool it, and machine it to obtain the finished piston ring. The sintering process is as follows: hold at 270℃ for 4 hours; raise the temperature to 380℃ and hold for 0.5 hours; lower the temperature to 220℃ and hold for 3 hours.

[0071] The polymer is chloromethylated polyether ether ketone, and the preparation method is the same as in Example 1.

[0072] The preparation method of nanoparticle hybrid graphite oxide is the same as step S1 in Example 1.

[0073] Comparative Example 8 The only difference between this example and Example 1 is that the coupling agent-modified multi-effect reinforcing filler in this example is prepared through the following steps: S1. Grafting Al2O3 and CeO2 onto carboxylated graphene oxide to obtain nanoparticle hybrid graphene oxide, the specific steps are the same as in Example 1; S2. Modifying nanoparticle-hybridized graphene oxide and nano-SiC with a silane coupling agent yields coupling agent-modified reinforced particles: S2-1. Add acetic acid to an alcohol-water solution composed of ethanol and deionized water in a volume ratio of 8:2, adjust the pH to 4.5-5.5, add silane coupling agent KH-570 to make the concentration of silane coupling agent 2wt%, and obtain a coupling agent solution. S2-2. Take 1.125g of nano-SiC and 1.875g of nanoparticle hybrid graphene oxide and add them to 100mL of ethanol. Disperse them by ultrasonication for 3h. Then add 10mL of coupling agent solution and stir at 75℃ for 6h. Filter the mixture. Wash the solid product with ethanol and dry it under vacuum at 90℃ for 12h to obtain coupling agent modified and reinforced particles. S3. Grafting chloromethylated polyetheretherketone and polyetherimide onto coupling agent-modified reinforcing particles yields coupling agent-modified multi-functional reinforcing filler: 5g of chloromethylated polyether ether ketone and 3g of polyetherimide were added to 150mL of DMAC and stirred at 80℃ for 10min to obtain a polymer solution. 4g of coupling agent-modified reinforcing particles were added to 50mL of DMAC and ultrasonically dispersed for 1h to obtain a particle dispersion. The particle dispersion was added to the polymer solution under stirring and ultrasonically dispersed for 90min. The mixture was then stirred at 85℃ for 8h, heated to 170℃ to evaporate the solvent, and the product was vacuum dried at 90℃ for 12h. After grinding, the coupling agent-modified multi-effect reinforcing filler was obtained.

[0074] Performance testing

[0075] Following the process methods for preparing finished piston rings in the various embodiments and comparative examples, samples were prepared to the required dimensions for subsequent testing.

[0076] 1. Wear resistance Wear resistance was tested using an HT-1000 high-temperature friction and wear testing machine. The friction pair was made of 45# steel (Rockwell hardness 50HRC, disc-shaped, 30mm in diameter, 7mm thick, roughness Ra 0.5µm), with a load of 70N, a sliding distance of 4000m, and a linear velocity of 1m / s. The volumetric wear rate K was tested at both room temperature and high temperature. Where ΔV is the wear volume (mm). 3 F is the load (N), and S is the total sliding distance (m).

[0077] When conducting high-temperature wear rate tests, the sample is first kept at 200℃ for 6 hours, and then the wear rate is tested using the same method.

[0078] The test results are shown in Table 1 below. Figure 3 :

[0079] The test results show that Examples 1-3 exhibit excellent wear resistance and high-temperature resistance, with Example 1 showing the best performance. Comparative Examples 1-8 all showed varying degrees of decrease in both room-temperature and high-temperature wear resistance. The decrease in wear resistance in Comparative Example 1 is mainly attributed to the lack of mullite phase formation in the coupling agent-modified reinforcing particles, which affected the bonding strength between the filler and the matrix, and the absence of the mullite phase's effect on improving wear resistance and heat resistance. The results of Comparative Example 2 indicate that CeO2 grafted onto carboxylated graphene oxide improves both wear resistance and high-temperature resistance. The performance decrease in Comparative Example 3 is attributed to the lack of silane coupling agent modification of the composite reinforcing particles, affecting their dispersibility in the matrix. The performance decrease in Comparative Example 4 is attributed to the lack of chloromethylated polyetheretherketone and polyetherimide grafting onto the coupling agent-modified reinforcing particles, affecting their compatibility with the piston ring matrix components. The performance degradation in Comparative Example 5 indicates that grafting only polyetherimide onto the coupling agent-modified reinforcing particles is less effective than simultaneously grafting chloromethylated polyetheretherketone and polyetherimide. This is because the latter grafting of both polymers achieves better compatibility with the piston ring matrix components. In Comparative Example 7, nano-SiC and nanoparticle-hybridized graphene oxide were directly added to the raw material system. These two inorganic fillers have poor compatibility with the polymer and polytetrafluoroethylene, making it difficult for them to exert their respective reinforcing effects, resulting in a significant decrease in wear resistance and high-temperature resistance. In Comparative Example 8, a physical mixture of SiC and nanoparticle-hybridized graphene oxide was used as a composite filler, and it underwent silane coupling agent modification, chloromethylated polyether ether ketone, and polyetherimide grafting treatment similar to that in Example 1. However, its wear resistance and high temperature resistance were significantly lower than those in Example 1. This is because Comparative Example 8 failed to form an organic composite system of SiC and nanoparticle-hybridized graphene oxide as in Example 1, and could not effectively achieve the complementary reinforcement effect between SiC and nanoparticle-hybridized graphene oxide. Therefore, the improvement effect on wear resistance and high temperature resistance was worse than that in Example 1.

[0080] 2. Tensile strength The tests were conducted according to the standard GB / T 1040.2-2022 "Determination of tensile properties of plastics—Part 2: Test conditions for molded and extruded plastics". The results are shown in Table 2 below. Figure 4 As shown.

[0081]

[0082] The test results show that Examples 1-3 have high tensile strength, with Example 1 showing the best performance; the tensile strength of Comparative Examples 1-8 all decreased to varying degrees.

[0083] 3. Hardness The hardness was tested using a Shore hardness tester, referring to the standard GB / T 2411-2008 "Determination of indentation hardness (Shore hardness) of plastics and hard rubber using a hardness tester". The test results are shown in Table 3 below. Figure 5 .

[0084]

[0085] The test results show that Examples 1-3 have high hardness, with Example 1 showing the best performance; the hardness of Comparative Examples 1-8 all decreased to varying degrees.

[0086] 4. Thermal conductivity Thermal conductivity was tested according to standard GB / T 42919.1-2023. The test results are shown in Table 4 below. Figure 6 .

[0087]

[0088] The test results show that Examples 1-3 have high thermal conductivity, with Example 1 showing the best performance; the thermal conductivity of Comparative Examples 1-8 all decreased to varying degrees.

[0089] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A polytetrafluoroethylene piston ring based on a coupling agent-modified multi-effect reinforced filler, characterized in that, The raw materials for its preparation include the following components by mass fraction: 5-20% coupling agent modified multi-effect reinforcing filler, 10-30% polymer, and the balance being polytetrafluoroethylene; The coupling agent-modified multi-effect reinforced filler is prepared through the following steps: S1. Grafting Al2O3 and CeO2 onto carboxylated graphene oxide yields nanoparticle hybrid graphene oxide. S2. SiC was synthesized in situ on nanoparticle-hybridized graphene oxide to obtain composite reinforcing particles; S3. Modify the composite reinforcing particles with a silane coupling agent to obtain coupling agent modified reinforcing particles; S4. Chloromethylated polyether ether ketone and polyether imide are grafted onto the coupling agent modified reinforcing particles to obtain coupling agent modified multi-effect reinforcing filler.

2. The polytetrafluoroethylene piston ring based on coupling agent-modified multi-effect reinforced filler according to claim 1, characterized in that, The polymer is chloromethylated polyether ether ketone, which is prepared by the following method: at 0~5°C, polyether ether ketone powder is dissolved in 95-98wt% concentrated sulfuric acid, chloromethyl octyl ether is added, the mixture is stirred and reacted, after the reaction is completed, the product is poured into an ice-water mixture, filtered, the product is washed and then added to N-methylpyrrolidone, stirred, filtered, the filtrate is poured into deionized water, filtered, and the solid product is dried to obtain chloromethylated polyether ether ketone.

3. The polytetrafluoroethylene piston ring based on coupling agent-modified multi-effect reinforced filler according to claim 2, characterized in that, Chloromethylated polyetheretherketone is prepared by the following method: At 0~5°C, 0.5-2g of polyetheretherketone powder is dissolved in 50-200mL of 98wt% concentrated sulfuric acid, and 5-20mL of chloromethyl octyl ether is added. The mixture is stirred for 1-4h. The product is then poured into 350-1400mL of an ice-water mixture under stirring, filtered, and the product is washed. 10-40mL of N-methylpyrrolidone is added, and the mixture is stirred for 10-40min. The mixture is filtered, and the filtrate is poured into deionized water. The solid product is dried to obtain chloromethylated polyetheretherketone.

4. The polytetrafluoroethylene piston ring based on coupling agent-modified multi-effect reinforced filler according to claim 1, characterized in that, The coupling agent-modified multi-effect reinforced filler is prepared through the following steps: S1. Grafting Al2O3 and CeO2 onto carboxylated graphene oxide: S1-1. Add graphene oxide to a mixed acid composed of sulfuric acid and nitric acid and heat under reflux to obtain carboxylated graphene oxide. S1-2. Carboxylated graphene oxide, CTAB, AlCl3, and Ce(NO3)3 are ultrasonically dispersed in deionized water to obtain solution A. S1-3. Add urea to deionized water and stir to obtain solution B. Add solution B dropwise to solution A. After the addition is complete, stir. Transfer the resulting mixture to a reaction vessel and react at 170-200℃ for 6-24 hours. Centrifuge to separate the precipitate, wash and dry it, and then calcine it at 600-800℃ for 3-8 hours to obtain nanoparticle hybrid graphene oxide. S2. In-situ synthesis of SiC on nanoparticle-hybridized graphene oxide: S2-1. Take silica sol, sucrose, composite reinforcing particles, Fe(NO3)3·9H2O, and deionized water, add them to ethanol, sonicate, stir, dry, and grind to obtain precursor powder. S2-2. Under argon protection, the precursor powder is first kept at 1500-1750℃ for 2-6 hours, then heated at 550-700℃ in air atmosphere for 1-4 hours. After cooling, it is soaked in sulfuric acid, filtered, washed and dried to obtain composite reinforced particles. S3. Modify the composite reinforcing particles using a silane coupling agent: S3-1. Add acid to an alcohol-water solution composed of ethanol and deionized water to adjust the pH to 4.5-5.5, then add silane coupling agent to obtain a coupling agent solution. S3-2. Disperse the composite reinforcing particles in ethanol, add the coupling agent solution, stir at 50-80℃ for 3-12h, filter, wash and dry to obtain coupling agent modified reinforcing particles. S4. Grafting chloromethylated polyetheretherketone and polyetherimide onto coupling agent modified reinforced particles: Chloromethylated polyether ether ketone and polyether imide were added to DMAC and heated and stirred to obtain a polymer solution. The coupling agent-modified reinforcing particles were dispersed in DMAC to obtain a particle dispersion. The particle dispersion was added to the polymer solution, ultrasonically dispersed, and stirred at 70-90℃ for 4-16h. The temperature was then raised to 165-175℃ to evaporate the solvent, dry the product, grind it, and obtain the coupling agent-modified multi-effect reinforcing filler.

5. The polytetrafluoroethylene piston ring based on coupling agent-modified multi-effect reinforced filler according to claim 4, characterized in that, Step S1 is as follows: S1-1. Add graphene oxide to a mixed acid consisting of 95wt% sulfuric acid and 60wt% nitric acid in a volume ratio of 2:1, heat under reflux at 60-100℃ for 3-12 hours, filter, wash and dry to obtain carboxylated graphene oxide. S1-2, Add 0.5-2g carboxylated graphene oxide, 0.07-0.3g CTAB, 0.25-1g AlCl3, and 0.05-0.22g Ce(NO3)3 to 50-200mL of deionized water and sonicate for 1-4h to obtain solution A; S1-3. Add 0.5-2g of urea to 5-20mL of deionized water and stir for 5-30min to obtain solution B. Add solution B dropwise to solution A while stirring. After the addition is complete, stir for 3-12h. Transfer the resulting mixture to a reaction vessel and react at 170-200℃ for 6-24h. Cool down, centrifuge, wash and dry the precipitate, grind it into powder, and then calcine it at 600-800℃ for 3-8h to obtain nanoparticle hybrid graphene oxide.

6. The polytetrafluoroethylene piston ring based on coupling agent-modified multi-effect reinforced filler according to claim 4, characterized in that, Step S2 is as follows: S2-1. Take 5-20g of silica sol with a SiO2 content of 20-30wt%, 3.5-15g of sucrose, 1-4g of composite reinforcing particles, 0.2-0.8g of Fe(NO3)3·9H2O, and 15-60mL of deionized water and add them to 35-140mL of ethanol. Sonicate for 1-4h, stir at 1500-7000rpm for 2-8h, dry at 100-150℃ for 10-48h, and grind to obtain precursor powder. S2-2. Under argon protection, the precursor powder is first kept at 1500-1600℃ for 0.5-2h, then heated to 1600-1750℃ and kept at that temperature for 1-3h. The resulting powder is then heated at 550-700℃ in air for 1-4h. After cooling, it is soaked in 10-30wt% sulfuric acid for 15-60min, filtered, washed, and dried to obtain composite reinforcing particles.

7. The polytetrafluoroethylene piston ring based on coupling agent-modified multi-effect reinforced filler according to claim 4, characterized in that, Step S3 is as follows: S3-1. Add acetic acid to an alcohol-water solution composed of ethanol and deionized water in a volume ratio of 8:2, adjust the pH to 4.5-5.5, add silane coupling agent to make the concentration of silane coupling agent 1-5wt%, and obtain a coupling agent solution. S3-2. Take 1.5-6g of composite reinforcing particles and add them to 50-200mL of ethanol. Disperse them by ultrasonication for 1.5-6h. Add 5-20mL of coupling agent solution and stir at 50-80℃ for 3-12h. Filter, wash and dry to obtain coupling agent modified reinforcing particles.

8. The polytetrafluoroethylene piston ring based on coupling agent-modified multi-effect reinforced filler according to claim 4, characterized in that, The silane coupling agent is selected from at least one of KH-550, KH-560, KH-570, and A-151.

9. The polytetrafluoroethylene piston ring based on coupling agent-modified multi-effect reinforced filler according to claim 4, characterized in that, Step S4 is as follows: Take 2.5-10g of chloromethylated polyether ether ketone and 1.5-6g of polyetherimide and add them to 75-300mL of DMAC. Stir at 70-90℃ for 5-20min to obtain a polymer solution. Add 2-8g of coupling agent modified reinforcing particles to 25-100mL of DMAC and ultrasonically disperse for 0.5-2h to obtain a particle dispersion. Add the particle dispersion to the polymer solution with stirring and ultrasonically disperse for 45-180min. Then stir and react at 70-90℃ for 4-16h. Raise the temperature to 165-175℃ to evaporate the solvent. Dry the product and grind it to obtain the coupling agent modified multi-effect reinforcing filler.

10. A method for preparing a polytetrafluoroethylene piston ring based on a coupling agent-modified multi-effect reinforcing filler as described in any one of claims 1-9, characterized in that, Includes the following steps: Step 1: After crushing and drying the polymer and polytetrafluoroethylene, mix them with the coupling agent-modified multi-effect reinforcing filler to obtain a raw material mixture; Step 2: Add the raw material mixture into the mold and press it into shape to obtain a piston ring blank; Step 3: Sinter the piston ring blank, cool it, and machine it to obtain the finished piston ring.

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