Intelligent piezoelectric response polymer-based self-lubricating material, preparation method and application thereof

Abstract

This invention discloses a smart piezoelectric-responsive polymer-based self-lubricating material, its preparation method, and its application, belonging to the field of robotics. The material, by volume percentage, comprises: 1-15% piezoelectric powder and 85-99% piezoelectric polymer; the piezoelectric powder is an oxide containing bismuth and other metals, or a composite of the oxide and carbon materials. The smart piezoelectric-responsive polymer-based self-lubricating material provided by this invention possesses excellent self-lubricating properties, wear resistance, and piezoelectric performance. Under the premise of enabling robot joint movement, it converts mechanical energy into electrical energy in pressure response. Homogeneous charges form at the interface, and the mutually repelling charges prevent interfacial interactions, thereby reducing friction and wear, forming a smart self-lubricating effect, saving additional power loss, and solving the lubrication technology problem of traditional robot active joints requiring frequent replacement due to high wear under dry friction conditions or the use of liquid lubricants such as oil, lean oil, or grease.

Description

Technical Field

[0001] This invention belongs to the field of robotics, specifically relating to the field of materials for robot joints, and more specifically to a smart piezoelectric responsive polymer-based self-lubricating material, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Joints are a crucial component of the human skeletal system, requiring mobility, stability, shock absorption and wear resistance, coordination, and flexibility. Joints ensure movement between connected bones, enabling the body to perform various complex movements and postures. Some joints need to absorb shocks and pressure to protect the body from injury. Through the coordinated work of joints, bones, and muscles, body movements become more coordinated and fluid, allowing for movement in different directions. Joints are equally vital in robotics. Due to the highly complex operating environments of robots, such as underwater and desert environments, lubrication of joints using oil, minimal oil, or grease is difficult. Therefore, intelligent conversion of interfacial mechanical forces, intelligent self-lubrication, and shock absorption and wear resistance are even more critical under dry friction conditions. Without protective measures, this can lead to low robot operating efficiency and shortened lifespan.

[0004] Robot joints require self-lubricating materials. Traditional self-lubricating materials cannot achieve intelligent conversion of interfacial mechanical forces, have high frictional damping, and a narrow operating temperature range, which affects the service life and application range of high-speed parallel robots.

[0005] Chinese patent CN116925483A discloses a lightweight, wear-resistant, self-lubricating polytetrafluoroethylene (PTFE) composite material. This material is prepared by blending polyethersulfone (PES) and PTFE to create a lightweight, low-cost PES / PTFE composite material with excellent friction-reducing and wear-resistant properties, good thermal stability, and high cost. Its application in the field of unmanned aerial vehicles (UAVs) and robots for engineering practice and teaching will effectively improve the performance and lifespan of their moving parts. Its advantages lie in its self-lubricating, self-repairing, and self-protecting functions, effectively improving the performance and lifespan of robot moving parts. Its disadvantages include: complex preparation, poor self-lubricating effect, inability to achieve intelligent conversion of interfacial mechanical forces, lack of intelligent self-lubricating function, and the still need for lubricating oil. Further improvements in self-lubricating effect are needed to achieve intelligent self-lubrication of robot joints under dry friction conditions. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a smart piezoelectric responsive polymer-based self-lubricating material, its preparation method, and its application. The smart piezoelectric responsive polymer-based self-lubricating material provided by the present invention can convert mechanical energy into electrical energy under pressure response conditions. The interface forms homogeneous charges, and the mutually repelling charges can reduce friction and wear, creating a smart self-lubricating effect. This solves the problems in existing technologies where robot joints suffer from high friction coefficients under dry friction conditions, leading to power waste, and high wear rates, resulting in rapid joint material wear.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] In a first aspect, the present invention provides a smart piezoelectric responsive polymer-based self-lubricating material, comprising, by volume percentage: 1-15% piezoelectric powder and 85-99% piezoelectric polymer.

[0009] The piezoelectric powder is an oxide containing bismuth and other metals, or a composite of the oxide and carbon materials.

[0010] In some embodiments of the present invention, the piezoelectric powder is selected from at least one of bismuth ferrite, bismuth tungstate, bismuth vanadate, bismuth niobate, bismuth ferrite / graphene oxide composite, bismuth tungstate / graphene oxide composite, bismuth vanadate / graphene oxide composite, bismuth niobate / graphene oxide composite, bismuth ferrite / carbon nanotube composite, bismuth tungstate / carbon nanotube composite, bismuth vanadate / carbon nanotube composite and / or bismuth niobate / carbon nanotube composite.

[0011] In some embodiments of the present invention, the piezoelectric powder is a micro / nano-scale powder.

[0012] In some embodiments of the present invention, the piezoelectric polymer includes one or more of polyvinylidene fluoride, polyacrylonitrile, polyamide-imide, polyvinyl chloride, nylon 11, perfluoroethylene-propylene copolymer, modified polyvinylidene fluoride, modified polyacrylonitrile, modified polyamide-imide, modified polyvinyl chloride, modified nylon 11 and / or modified perfluoroethylene-propylene copolymer.

[0013] In some embodiments of the present invention, the modification is performed by using a conductive alkylimidazolium ionic liquid as a modifier to obtain modified polyvinylidene fluoride, modified polyacrylonitrile, modified polyamide-imide, modified polyvinyl chloride, modified nylon 11, or modified perfluoroethylene-propylene copolymer by melt blending.

[0014] In some embodiments of the present invention, the alkylimidazolium ionic liquid is one of 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-butyl-3-methylimidazolium hydrogen sulfate.

[0015] In some embodiments of the present invention, the composition by volume percentage includes: 1-10% piezoelectric powder and 90-99% piezoelectric polymer.

[0016] In some embodiments of the present invention, the composition by volume percentage includes: 1-10% piezoelectric powder and 90-99% piezoelectric polymer.

[0017] The piezoelectric powder is one of bismuth ferrite, bismuth tungstate, bismuth vanadate, or bismuth niobate.

[0018] In some embodiments of the present invention, the composition by volume percentage is: 5% piezoelectric powder and 95% piezoelectric polymer.

[0019] The piezoelectric powder is bismuth ferrite, and the piezoelectric polymer is polyvinylidene fluoride.

[0020] In some embodiments of the present invention, the composition by volume percentage is: 3-7% piezoelectric powder and 93-97% piezoelectric polymer.

[0021] The piezoelectric powder is one of bismuth ferrite, bismuth tungstate, bismuth vanadate, or bismuth niobate;

[0022] The piezoelectric polymer is a material modified by melt blending with alkylimidazolium ionic liquid as a modifier and polyvinylidene fluoride, polyacrylonitrile, polyamide-imide, polyvinyl chloride, nylon 11 or perfluoroethylene-propylene copolymer as a polymer matrix.

[0023] In some embodiments of the present invention, the composition by volume percentage is: 5% piezoelectric powder and 95% piezoelectric polymer.

[0024] The piezoelectric powder is bismuth ferrite, and the piezoelectric polymer is polyvinylidene fluoride modified with alkyl imidazole ionic liquid.

[0025] A second aspect of the present invention provides a method for preparing the above-mentioned smart piezoelectric responsive polymer-based self-lubricating material, comprising:

[0026] Piezoelectric powder and piezoelectric polymer are mixed in a certain proportion to obtain a mixture, which is then molded to obtain a smart piezoelectric responsive polymer-based self-lubricating material.

[0027] In some embodiments of the present invention, the molding is compression molding or injection molding;

[0028] The compression molding process involves a molding pressure of 6–24 MPa and a molding temperature of 350–390 °C.

[0029] A third aspect of the present invention provides an application of the above-described intelligent piezoelectric responsive polymer-based self-lubricating material or the intelligent piezoelectric responsive polymer-based self-lubricating material prepared by the above-described preparation method in robots.

[0030] In some embodiments of the present invention, smart piezoelectric responsive polymer-based self-lubricating materials are used in the moving joints of robots.

[0031] The beneficial effects of this invention are as follows:

[0032] The intelligent piezoelectric responsive polymer-based self-lubricating material provided by this invention possesses excellent wear resistance, piezoelectric response, and intelligent self-lubricating properties. Under pressure response, this material can convert mechanical energy into electrical energy, accumulating homogeneous charges at the interface and forming a repulsive effect, thereby improving lubricity and wear resistance. This invention adds a specific proportion of piezoelectric powder to the piezoelectric polymer, enabling the intelligent responsive interface to convert pressure into electrical energy, forming homogeneous charge repulsion, blocking the interaction between material interfaces, thereby reducing the coefficient of friction, increasing wear resistance, and reducing energy dissipation. This invention can modify the intelligent self-lubricating, wear-resistant, and piezoelectric responsive properties of the resulting intelligent piezoelectric responsive polymer-based self-lubricating material by changing the type and ratio of the piezoelectric polymer, allowing for the preparation of intelligent piezoelectric responsive polymer-based self-lubricating materials that meet different performance requirements according to actual needs.

[0033] The preparation method of the intelligent piezoelectric responsive polymer-based self-lubricating material provided by this invention is simple, low in cost, and easy to implement. Attached Figure Description

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0035] Figure 1 This is a diagram illustrating the synthesis reaction mechanism of bismuth ferrite / carbon nanotube composites, showing that the reaction examples are applicable to all piezoelectric materials.

[0036] Figure 2 Diagram showing polymer modification and its preparation mechanism;

[0037] Figure 3 A diagram illustrating the charge repulsion mechanism of the intelligent piezoelectric-responsive polymer-based self-lubricating material provided by this invention;

[0038] Figure 4 A piezoelectric mechanism diagram of the intelligent piezoelectric-responsive polymer-based self-lubricating material provided by the present invention;

[0039] Figure 5 This is a SEM image of bismuth ferrite prepared in Example 1 of the present invention;

[0040] Figure 6 This is a graph showing the change in the coefficient of friction between the intelligent piezoelectric response polymer-based self-lubricating material and pure PVDF material under different pressures, as provided in Embodiment 1 of the present invention.

[0041] Figure 7 This is a wear variation diagram of the intelligent piezoelectric response polymer-based self-lubricating material and pure PVDF material under different pressures, as provided in Embodiment 1 of the present invention.

[0042] Figure 8 The graph shows the change in friction coefficient of the intelligent piezoelectric response polymer-based self-lubricating material provided in Examples 5-7 of this invention under a pressure of 10N.

[0043] Figure 9 The wear variation diagrams of the intelligent piezoelectric response polymer-based self-lubricating materials provided in Examples 5-7 of the present invention under 10N pressure are shown. Detailed Implementation

[0044] It should be noted that the term "intelligent self-lubrication" refers to a lubrication phenomenon that converts mechanical energy into electrical energy. The intelligent piezoelectric-responsive polymer-based self-lubricating material provided by this invention possesses intelligent self-lubricating functionality. Under pressure response, it converts mechanical energy into electrical energy, forming homogeneous charges at the interface. These repulsive charges prevent interfacial interactions, thereby reducing friction and wear, creating an intelligent self-lubricating effect. This saves additional power loss and solves the lubrication technology problem of traditional robot active joints requiring frequent replacement due to high wear under dry friction conditions or the use of liquid lubricants such as oil, lean oil, or grease.

[0045] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] A first typical embodiment of the present invention provides a smart piezoelectric responsive polymer-based self-lubricating material, comprising, by volume percentage: 1-15% piezoelectric powder and 85-99% piezoelectric polymer.

[0047] The piezoelectric powder is an oxide containing bismuth and other metals, or a composite of the oxide and carbon materials.

[0048] In the field of robotics, robots operate in highly complex and changing environments such as underwater, desert, and space. Lubrication of joints using oil, low-oil lubrication, or grease is difficult to achieve. Therefore, self-lubrication (especially intelligent self-lubrication), shock absorption, and wear resistance are crucial under dry friction conditions. To address this, this invention utilizes piezoelectric powder and piezoelectric polymers to prepare an intelligent piezoelectric responsive polymer self-lubricating material with excellent piezoelectric properties. Compared to existing technologies, the intelligent piezoelectric responsive polymer-based self-lubricating material provided by this invention exhibits superior intelligent self-lubrication, wear resistance, and piezoelectric performance. While enabling robot joint movement, this material can convert mechanical energy into electrical energy under pressure response. The interface forms homogeneous charges, and the repulsive charges prevent interfacial interactions, thereby reducing friction and wear, creating an intelligent self-lubricating effect, saving additional power loss, and solving the lubrication problem of traditional robot active joints requiring frequent replacement due to high wear or the use of oil, low-oil lubricant, or grease under dry friction conditions.

[0049] Furthermore, the intelligent piezoelectric responsive polymer-based self-lubricating material provided by this invention can be further modified by adding other powders, such as adding other powders to change the energy consumption problem.

[0050] In the intelligent piezoelectric responsive polymer-based self-lubricating material provided by this invention, the content of piezoelectric powder, by volume percentage, can specifically be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%; the content of the piezoelectric polymer can specifically be 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%.

[0051] In the intelligent piezoelectric responsive polymer-based self-lubricating material provided by the present invention, the piezoelectric powder is selected from at least one of bismuth ferrite (BiFeO3), bismuth tungstate (Bi2WO6), bismuth vanadate (BiVO4), bismuth niobate (Bi3NbO7), bismuth ferrite / graphene oxide composite (BiFeO3@GrO), bismuth tungstate / graphene oxide composite (Bi2WO6@GrO), bismuth vanadate / graphene oxide composite (BiVO4@GrO), bismuth niobate / graphene oxide composite (Bi3NbO7@GrO), bismuth ferrite / carbon nanotube composite (BiFeO3@CNTs), bismuth tungstate / carbon nanotube composite (Bi2WO6@CNTs), bismuth vanadate / carbon nanotube composite (BiVO4@CNTs), and / or bismuth niobate / carbon nanotube composite (Bi3NbO7@CNTs).

[0052] The aforementioned piezoelectric powders possess piezoelectricity, lubricity, and wear resistance, along with excellent ferroelectricity and antiferromagnetism. They exhibit high mechanical strength and chemical stability, resisting corrosion from acids, alkalis, and organic solutions. Furthermore, they readily generate homogeneous charges during friction. Their superior wear resistance, piezoelectric response, and lubricity help reduce power loss caused by joint movement. The antiferromagnetic Nell's point of these piezoelectric powders is 370–450°C, meaning they exhibit multiferroic properties and homogeneous charge generation at room temperature, indicating significant application potential in multiple fields.

[0053] The addition of the aforementioned piezoelectric powder to piezoelectric polymers can improve the wear resistance and piezoelectric response of the piezoelectric polymers, thereby enhancing the intelligent self-lubricating properties of intelligent piezoelectric response polymer-based self-lubricating materials.

[0054] It should be noted that the bismuth ferrite, bismuth tungstate, bismuth vanadate, and bismuth niobate in the above piezoelectric powders are conventional products that can be purchased commercially or prepared in-house.

[0055] Bismuth ferrite, bismuth tungstate, bismuth vanadate, and bismuth niobate can be prepared using the following methods.

[0056] Preparation method of bismuth ferrite powder:

[0057] According to the required molar mass fraction, with a Bi to Fe molar ratio of 1:1, bismuth ions (Bi) are provided to 500 mL of basic bismuth nitrate ([Bi6O6(OH)3](NO3)3·1.5H2O, 0.1 mol / L). 3+ ) and ferric sulfate (Fe2(SO4)3·7H2O, 0.1mol / L, providing iron ions Fe) 3+ Add ammonia to the solution until bismuth and iron ions in the mixture are completely precipitated. Filter with deionized water to completely remove the precipitate, and rinse the filter with deionized water. Add a small amount of ammonia (2M) and the filter to a hydrothermal reactor, ensuring that the total volume of all materials added to the reactor does not exceed 1 / 3 of the total volume of the reactor lining. Stir with a glass rod to ensure uniform mixing of the materials in the reactor, and carry out the hydrothermal reaction. After the reaction is complete, filter and dry to obtain bismuth ferrite powder.

[0058] The hydrothermal reaction was carried out at a temperature of 200°C for 24 hours. Both temperature and reaction time affect the purity of bismuth ferrite. Under the specified temperature and time, all bismuth ferrite samples exhibited high purity.

[0059] The solution containing basic bismuth nitrate and ferric sulfate contains acetic acid, and the mixture is acidified with acetic acid to increase its solubility.

[0060] After the hydrothermal reaction is completed, the mixture is filtered and washed with deionized water to remove all the precipitate. The filtered material is then rinsed with deionized water and dried to obtain bismuth ferrite powder.

[0061] It should be noted that the drying can be carried out using any device and at any temperature, as long as it can remove deionized water. For example, an oven can be used for drying at 70°C for 4 hours.

[0062] The synthesis processes of bismuth tungstate, bismuth vanadate, and bismuth niobate are similar to those of bismuth ferrite, as detailed below.

[0063] Preparation method of bismuth tungstate:

[0064] According to the required molar mass fraction, the molar ratio of Bi to W is 2:1. Bismuth ions (Bi) are provided to 500 mL of basic bismuth nitrate ([Bi6O6(OH)3](NO3)3·1.5H2O, 0.1 mol / L). 3+ ) and sodium tungstate dihydrate (Na2WO4·2H2O, 0.1mol / L, providing tungsten ions W) 6+ Add ammonia to the solution until bismuth and tungsten ions are completely precipitated. Filter with deionized water to completely remove the precipitate, and rinse the filter with deionized water. Add a small amount of ammonia (2M) and the filter to a hydrothermal reactor, ensuring that the total volume of all materials added to the reactor does not exceed 1 / 3 of the total volume of the reactor lining. Stir with a glass rod to ensure uniform mixing of the materials in the reactor, and carry out the hydrothermal reaction. After the reaction is complete, filter and dry to obtain bismuth ferrite powder.

[0065] The hydrothermal reaction was conducted at a temperature of 200°C for 24 hours. Both temperature and reaction time affect the purity of bismuth tungstate. Under the specified temperature and time, the obtained bismuth tungstate exhibits high purity.

[0066] The solution containing basic bismuth nitrate and sodium tungstate dihydrate contains acetic acid, and the mixture is acidified with acetic acid to increase its solubility.

[0067] After the hydrothermal reaction is completed, the mixture is filtered and washed with deionized water to remove all the precipitate. The filtered material is then rinsed with deionized water and dried to obtain bismuth tungstate powder.

[0068] It should be noted that the drying can be carried out using any device and at any temperature, as long as it can remove deionized water. For example, an oven can be used for drying at 70°C for 4 hours.

[0069] Preparation method of bismuth vanadate powder:

[0070] According to the required molar mass fraction, with a Bi to V molar ratio of 2:1, 500 mL of basic bismuth nitrate ([Bi6O6(OH)3](NO3)3·1.5H2O, 0.1 mol / L) is used to provide bismuth ions Bi. 3+ ) and ammonium metavanadate (NH4VO3, 0.1 mol / L, providing vanadium ions V 5+ Add ammonia to the solution until bismuth and vanadium ions are completely precipitated. Filter with deionized water to completely remove the precipitate. Rinse the filter with deionized water. Add a small amount of ammonia (2M) and the filter to a hydrothermal reactor, ensuring that the total volume of all materials added to the reactor does not exceed 1 / 3 of the total volume of the reactor lining. Stir with a glass rod to ensure uniform mixing of the materials in the reactor and carry out the hydrothermal reaction. After the reaction is complete, filter and dry to obtain bismuth vanadate powder.

[0071] The hydrothermal reaction was conducted at a temperature of 200°C for 24 hours. Both temperature and reaction time affect the purity of bismuth vanadate. Under the specified temperature and time, the obtained bismuth vanadate exhibits high purity.

[0072] The solution containing basic bismuth nitrate and ammonium metavanadate contains acetic acid, and the mixture is acidified with acetic acid to increase its solubility.

[0073] After the hydrothermal reaction is completed, the mixture is filtered and washed with deionized water to remove all the precipitate. The filtered material is then rinsed with deionized water and dried to obtain bismuth vanadate powder.

[0074] It should be noted that the drying can be carried out using any device and at any temperature, as long as it can remove deionized water. For example, an oven can be used for drying at 70°C for 4 hours.

[0075] Preparation method of bismuth niobate powder:

[0076] According to the required molar mass fraction, the molar ratio of Bi to Nb is 2:1. Bismuth ions are provided to 500 mL of basic bismuth nitrate ([Bi6O6(OH)3](NO3)3·1.5H2O, 0.1 mol / L). 3+ ) and potassium hexaniobate (K 8-x H x Nb6O 19 ·nH₂O, 0.1 mol / L, provides niobium ions (Nb). 5+Add ammonia to the solution until bismuth and niobium ions are completely precipitated. Filter with deionized water to completely remove the precipitate, and rinse the filter with deionized water. Add a small amount of ammonia (2M) and the filter to a hydrothermal reactor, ensuring that the total volume of all materials added to the reactor does not exceed 1 / 3 of the total volume of the reactor lining. Stir with a glass rod to ensure uniform mixing of the materials in the reactor, and carry out the hydrothermal reaction. After the reaction is complete, filter and dry to obtain bismuth niobate powder.

[0077] The hydrothermal reaction was conducted at a temperature of 200°C for 24 hours. Both temperature and reaction time affect the purity of bismuth niobate. Under the specified temperature and time, the obtained bismuth niobate exhibits high purity.

[0078] The solution containing basic bismuth nitrate and potassium hexaniobate contains acetic acid, and the mixture is acidified with acetic acid to increase its solubility.

[0079] After the hydrothermal reaction is completed, the mixture is filtered and washed with deionized water to remove all the precipitate. The filtered material is then rinsed with deionized water and dried to obtain bismuth niobate powder.

[0080] It should be noted that the drying can be carried out using any device and at any temperature, as long as it can remove deionized water. For example, an oven can be used for drying at 70°C for 4 hours.

[0081] It should be noted that the bismuth ferrite / graphene oxide composite, bismuth tungstate / graphene oxide composite, bismuth vanadate / graphene oxide composite, bismuth niobate / graphene oxide composite, bismuth ferrite / carbon nanotube composite, bismuth tungstate / carbon nanotube composite, bismuth vanadate / carbon nanotube composite and / or bismuth niobate / carbon nanotube composite in the above-mentioned piezoelectric powders are conventional products that can be purchased commercially or prepared in-house.

[0082] The following methods can be used to prepare bismuth ferrite / graphene oxide composites, bismuth tungstate / graphene oxide composites, bismuth vanadate / graphene oxide composites, bismuth niobate / graphene oxide composites, bismuth ferrite / carbon nanotube composites, bismuth tungstate / carbon nanotube composites, bismuth vanadate / carbon nanotube composites, and / or bismuth niobate / carbon nanotube composites.

[0083] First, graphene oxide (GO) was prepared from natural graphite powder via a modified Hummers method. Preparation method of bismuth ferrite / graphene oxide composite:

[0084] According to the required molar mass fraction, the molar ratio of Bi to Fe is 1:1. Take 500 mL of basic bismuth nitrate ([Bi6O6(OH)3](NO3)3·1.5H2O, 0.1 mol / L) to provide bismuth ions Bi.3+ ) and ferric sulfate (Fe2(SO4)3·7H2O, 0.1mol / L, providing iron ions Fe) 3+ A solution of bismuth ferrite (BFeO3@GrO3) was prepared. Simultaneously, a certain amount of pre-prepared GO solution was added to the above solution. After ultrasonic vibration for 3 hours and mechanical stirring for 1 hour, a suspension with uniformly dispersed GO was obtained. Ammonia water was added to the suspension until bismuth and iron ions were completely precipitated. The mixture was then filtered with deionized water to completely remove the precipitate. The filter material was rinsed with deionized water. A small amount of ammonia water (2M) and the filter material were added to a hydrothermal reactor, ensuring that the total volume of all materials added to the reactor did not exceed 1 / 3 of the total volume of the reactor lining. The mixture was stirred with a glass rod to ensure uniform mixing, and the hydrothermal reaction was carried out. The product was washed several times with deionized water and ethanol, and dried to finally obtain bismuth ferrite / graphene oxide (BiFeO3@GrO3) composite materials with graphene oxide mass contents of 1%, 3%, and 5%.

[0085] Before the reaction, the reaction vessel is cleaned with dilute nitric acid.

[0086] The solution containing basic bismuth nitrate and ferric sulfate contains acetic acid, and the mixture is acidified with acetic acid to increase its solubility.

[0087] The hydrothermal reaction was conducted at a temperature of 200°C for 24 hours. Both temperature and reaction time affect the purity of the bismuth ferrite / graphene oxide composite. Under the specified temperature and time, the obtained bismuth ferrite / graphene oxide composite exhibited high purity.

[0088] After the hydrothermal reaction is completed, deionized water is used for filtration to remove all the precipitate in the mixture. The filtrate is then rinsed with deionized water and ethanol. After washing, the filtrate is dried to obtain bismuth ferrite powder.

[0089] It should be noted that the drying can be carried out using any device and at any temperature, as long as it can remove deionized water and ethanol. For example, it can be dried in an oven at 70°C for 4 hours; or it can be dried in a vacuum drying oven at 80°C for 24 hours.

[0090] Preparation methods of bismuth ferrite / carbon nanotube composites, such as Figure 1 As shown (it should be noted that, Figure 1 The demonstrated synthetic reaction mechanism is applicable to all piezoelectric powders:

[0091] Based on the required molar mass fraction, with a Bi to Fe molar ratio of 1:1, take 500 mL of 0.1 mol / L basic bismuth nitrate ([Bi6O6(OH)3](NO3)3·1.5H2O, 0.1 mol / L) to provide bismuth ions Bi. 3+) and ferric sulfate (Fe2(SO4)3·7H2O, 0.1mol / L, providing iron ions Fe) 3+ A solution of carbon nanotubes (CNTs) was prepared. Commercially available CNTs were used; 1%, 3%, and 5% alkaline solutions of CNTs were prepared as needed. A certain amount of the pre-prepared alkaline CNT solutions was added to the above solutions. After ultrasonic vibration for 3 hours and mechanical stirring for 1 hour, a suspension of CNTs with uniform dispersion was obtained. Ammonia was added to the suspension until bismuth and iron ions were completely precipitated. The mixture was then filtered with deionized water to completely remove the precipitate. The filter was rinsed with deionized water. A small amount of ammonia (2M) and the filter were added to a 150 mL Teflon-coated hydrothermal reactor, ensuring that the total volume of all materials added to the reactor did not exceed 1 / 3 of the total volume of the reactor lining. The mixture was stirred with a glass rod to ensure uniform mixing, and the hydrothermal reaction was carried out (after holding at 200℃ for 24 hours). The product was washed several times with deionized water and ethanol and dried to finally obtain bismuth ferrite / carbon nanotube (BiFeO3@CNTs) composite materials with carbon nanotube mass contents of 1%, 3% and 5%.

[0092] Preparation method of bismuth tungstate / graphene oxide composite:

[0093] According to the required molar mass fraction, the molar ratio of Bi to W is 2:1. Take 500 mL of basic bismuth nitrate ([Bi6O6(OH)3](NO3)3·1.5H2O, 0.1 mol / L) to provide bismuth ions Bi. 3+ ) and sodium tungstate dihydrate (Na2WO4·2H2O, 0.1mol / L, providing tungsten ions W) 6+ A solution of GO was prepared; simultaneously, a certain amount of pre-prepared GO solution was added to the above solution, and the mixture was ultrasonically vibrated for 3 hours and mechanically stirred for 1 hour to obtain a GO suspension with uniform dispersion. Ammonia water was added to the suspension until bismuth and tungsten ions in the suspension were completely precipitated. The mixture was then filtered with deionized water to completely remove the precipitate, and the filter was rinsed with deionized water. A small amount of ammonia water (2M) and the filter were added to a 150 mL Teflon-coated thermoelectric reactor to ensure that the total volume of all materials added to the reactor did not exceed 1 / 3 of the total volume of the reactor liner. The mixture was stirred with a glass rod to ensure uniform mixing of the materials in the reactor, and the hydrothermal reaction was carried out (after holding at 200℃ for 24 hours). The product was washed several times with deionized water and ethanol, dried, and finally, bismuth tungstate / graphene oxide (Bi2WO6@GrO) composite materials with a graphene oxide mass content of 1%, 3%, and 5% were obtained.

[0094] Preparation method of bismuth tungstate / carbon nanotube composite:

[0095] According to the required molar mass fraction, the molar ratio of Bi to W is 2:1. Take 500 mL of basic bismuth nitrate ([Bi6O6(OH)3](NO3)3·1.5H2O, 0.1 mol / L) to provide bismuth ions Bi. 3+ ) and sodium tungstate dihydrate (Na2WO4·2H2O, 0.1mol / L, providing tungsten ions W) 6+ A solution of carbon nanotubes (CNTs) was prepared. Commercially available CNTs were used, and alkaline solutions of 1%, 3%, and 5% CNTs were prepared as needed. A certain amount of the pre-prepared alkaline CNT solution was added to the above solutions. After ultrasonic vibration for 3 hours and mechanical stirring for 1 hour, a suspension with uniformly dispersed CNTs was obtained. Ammonia was added to the suspension until bismuth and tungsten ions were completely precipitated. The mixture was then filtered with deionized water to completely remove the precipitate. The filter was rinsed with deionized water. A small amount of ammonia (2M) and the filter were added to a 150 mL Teflon-coated hydrothermal reactor, ensuring that the total volume of all materials added to the reactor did not exceed 1 / 3 of the total volume of the reactor lining. The mixture was stirred with a glass rod to ensure uniform mixing, and the hydrothermal reaction was carried out (after holding at 200℃ for 24 hours). The product was washed several times with deionized water and ethanol and dried to finally obtain bismuth tungstate / carbon nanotube (Bi2WO6@CNTs) composite materials with carbon nanotube mass contents of 1%, 3% and 5%.

[0096] Preparation method of bismuth vanadate / graphite oxide composite:

[0097] According to the required molar mass fraction, with a Bi to V molar ratio of 2:1, take 500 mL of basic bismuth nitrate ([Bi6O6(OH)3](NO3)3·1.5H2O, 0.1 mol / L) to provide bismuth ions Bi. 3+ ) and ammonium metavanadate (NH4VO3, 0.1 mol / L, providing vanadium ions V 5+ A solution of bismuth vanadium oxide (BVO4@GrO2) was prepared. Simultaneously, a certain amount of pre-prepared GO solution was added to the above solution. After ultrasonic vibration for 3 hours and mechanical stirring for 1 hour, a uniformly dispersed GO suspension was obtained. Ammonia was added to the suspension until bismuth and vanadium ions were completely precipitated. The mixture was then filtered with deionized water to completely remove the precipitate. The filter was rinsed with deionized water. A small amount of ammonia (2M) and the filter were added to a 150 mL Teflon-coated hydrothermal reactor, ensuring that the total volume of all materials added to the reactor did not exceed 1 / 3 of the total volume of the reactor lining. The mixture was stirred with a glass rod to ensure uniform mixing, and a hydrothermal reaction was carried out (held at 200℃ for 24 hours). The product was washed several times with deionized water and ethanol, and dried to finally obtain bismuth vanadate / graphene oxide (BiVO4@GrO2) composite materials with graphene oxide mass contents of 1%, 3%, and 5%.

[0098] Preparation method of bismuth vanadate / carbon nanotube composite:

[0099] According to the required molar mass fraction, with a Bi to V molar ratio of 2:1, take 500 mL of basic bismuth nitrate ([Bi6O6(OH)3](NO3)3·1.5H2O, 0.1 mol / L) to provide bismuth ions Bi. 3+ ) and ammonium metavanadate (NH4VO3, 0.1 mol / L, providing vanadium ions V 5+ A solution of carbon nanotubes (CNTs) was prepared. Commercially available CNTs were used, and alkaline solutions of 1%, 3%, and 5% CNTs were prepared as needed. A certain amount of the pre-prepared alkaline CNT solution was added to the above solutions. After ultrasonic vibration for 3 hours and mechanical stirring for 1 hour, a suspension with uniformly dispersed CNTs was obtained. Ammonia was added to the suspension until bismuth and vanadium ions were completely precipitated. The mixture was then filtered with deionized water to completely remove the precipitate. The filter was rinsed with deionized water. A small amount of ammonia (2M) and the filter were added to a 150 mL Teflon-coated hydrothermal reactor, ensuring that the total volume of all materials added to the reactor did not exceed 1 / 3 of the total volume of the reactor liner. The mixture was stirred with a glass rod to ensure uniform mixing, and the hydrothermal reaction was carried out (after holding at 200℃ for 24 hours). The product was washed several times with deionized water and ethanol and dried to finally obtain bismuth vanadate / carbon nanotube (BiVO4@CNTs) composite materials with carbon nanotube mass contents of 1%, 3% and 5%.

[0100] Preparation method of bismuth niobate / graphene oxide composite:

[0101] According to the required molar mass fraction, the molar ratio of Bi to Nb is 2:1. Take 500 mL of basic bismuth nitrate ([Bi6O6(OH)3](NO3)3·1.5H2O, 0.1 mol / L) to provide bismuth ions Bi. 3+ ) and potassium hexaniobate (K 8-x H x Nb6O 19 ·nH₂O, 0.1 mol / L, provides niobium ions (Nb). 5+A solution of bismuth niobate (BNO) was prepared; simultaneously, a certain amount of pre-prepared GO solution was added to the above solution, and the mixture was ultrasonically vibrated for 3 hours and mechanically stirred for 1 hour to obtain a uniformly dispersed suspension of GO. Ammonia water was added to the suspension until bismuth and niobium ions in the suspension were completely precipitated. The mixture was then filtered with deionized water to completely remove the precipitate, and the filter was rinsed with deionized water. A small amount of ammonia water (2M) and the filter were added to a 150 mL Teflon-coated hydrothermal reactor to ensure that the total volume of all materials added to the reactor did not exceed 1 / 3 of the total volume of the reactor liner. The mixture was stirred with a glass rod to ensure that the materials in the reactor were mixed evenly, and the hydrothermal reaction was carried out (after holding at 200℃ for 24 hours). The product was washed several times with deionized water and ethanol, and dried to finally obtain bismuth niobate / graphene oxide (Bi3NbO7@GrO) composite materials with a graphene oxide mass content of 1%, 3%, and 5%.

[0102] Preparation method of bismuth niobate / carbon nanotube composite:

[0103] According to the required molar mass fraction, the molar ratio of Bi to Nb is 2:1. Take 500 mL of basic bismuth nitrate ([Bi6O6(OH)3](NO3)3·1.5H2O, 0.1 mol / L) to provide bismuth ions Bi. 3+ ) and potassium hexaniobate (K 8-x H x Nb6O 19 ·nH₂O, 0.1 mol / L, provides niobium ions (Nb). 5+ A solution of carbon nanotubes (CNTs) was prepared. Commercially available CNTs were used to prepare 1%, 3%, and 5% alkaline solutions of CNTs as needed. A certain amount of the pre-prepared alkaline CNT solution was added to the above solutions. After ultrasonic vibration for 3 hours and mechanical stirring for 1 hour, a uniformly dispersed suspension of the alkaline CNT solution was obtained. Ammonia was added to the suspension until bismuth and niobium ions were completely precipitated. The mixture was then filtered with deionized water to completely remove the precipitate. The filter was rinsed with deionized water. A small amount of ammonia (2M) and the filter were added to a 150 mL Teflon-coated hydrothermal reactor, ensuring that the total volume of all materials added to the reactor did not exceed 1 / 3 of the total volume of the reactor liner. The mixture was stirred with a glass rod to ensure uniform mixing, and the hydrothermal reaction was carried out (after holding at 200℃ for 24 hours). The product was washed several times with deionized water and ethanol, and then dried to finally obtain bismuth niobate / carbon nanotube (Bi3NbO7@CNTs) composite materials with carbon nanotube mass contents of 1%, 3%, and 5%.

[0104] In the intelligent piezoelectric responsive polymer-based self-lubricating material provided by the present invention, the piezoelectric powder is a micro-nano-scale powder.

[0105] In the intelligent piezoelectric responsive polymer-based self-lubricating material provided by this invention, the piezoelectric polymer is a thermoplastic. Thermoplastics can be repeatedly softened or melted, facilitating mold processing. Using thermoplastic materials improves the operability and service life of the intelligent piezoelectric responsive polymer-based self-lubricating material. Furthermore, adding a certain amount of piezoelectric powder to the thermoplastic enhances its piezoelectric properties, and ensures excellent piezoelectric performance while maintaining good mechanical properties (wear resistance, etc.) for the intelligent piezoelectric responsive polymer-based self-lubricating material.

[0106] In the intelligent piezoelectric responsive polymer-based self-lubricating material provided by this invention, the piezoelectric polymer includes one or more of polyvinylidene fluoride, polyacrylonitrile, polyamide-imide, polyvinyl chloride, nylon 11, perfluoroethylene-propylene copolymer, modified polyvinylidene fluoride, modified polyacrylonitrile, modified polyamide-imide, modified polyvinyl chloride, modified nylon 11, and / or modified perfluoroethylene-propylene copolymer. All of the above-mentioned piezoelectric polymers possess excellent piezoelectricity, wear resistance, lubrication, and mechanical strength, as well as excellent resistance to ultraviolet radiation and high-energy radiation.

[0107] It should be noted that the polyvinylidene fluoride, polyacrylonitrile, polyamide-imide, polyvinyl chloride, nylon 11, and perfluoroethylene-propylene copolymer are conventional products and are commercially available. The modified polyvinylidene fluoride, modified polyacrylonitrile, modified polyamide-imide, modified polyvinyl chloride, modified nylon 11, and / or modified perfluoroethylene-propylene copolymer are obtained through ionic liquid modification, and the modification methods are the same.

[0108] In the intelligent piezoelectric responsive polymer-based self-lubricating material provided by the present invention, the modification is to obtain modified polyvinylidene fluoride, modified polyacrylonitrile, modified polyamide-imide, modified polyvinyl chloride, modified nylon 11 or modified perfluoroethylene-propylene copolymer by melt blending with a conductive alkylimazole ionic liquid as a modifier.

[0109] In the intelligent piezoelectric responsive polymer-based self-lubricating material provided by the present invention, the alkyl imidazole ionic liquid is one of 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-butyl-3-methylimidazolium hydrogen sulfate.

[0110] The structures of the five ionic liquids are as follows:

[0111]

[0112]

[0113] It should be noted that the preparation method of the modified polymer is as follows, such as... Figure 2 As shown (it should be noted that, Figure 2 Using polyvinylidene fluoride and polyvinyl chloride as polymer matrices and 1-butyl-3-methylimidazolium bromide as a modifier, a modified composite material is obtained through melt blending. This modified composite material is then mixed with piezoelectric powder bismuth ferrite and molded to obtain a smart piezoelectric responsive polymer-based self-lubricating material.

[0114] Five alkylimidazolium ionic liquids (ILs) with high intrinsic dielectric constant, low dielectric loss, and good mechanical properties were selected as polymer matrices: polyvinylidene fluoride, polyacrylonitrile, polyamide-imide, polyvinyl chloride, nylon 11, or perfluoroethylene-propylene copolymer. The ILs were: 1-butyl-3-methylimidazolium bromide ([Bmim]Br), 1-butyl-3-methylimidazolium chloride ([Bmim]Cl), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]Br), and 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]Cl). Using [Bmim]PF6, 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF6), or 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim]HSO4) as modifiers, ionic liquid IL-modified polyvinylidene fluoride, modified polyacrylonitrile, modified polyamide-imide, modified polyvinyl chloride, modified nylon 11, and modified perfluoroethylene-propylene copolymer composites were prepared by melt blending. The microstructure and electrical properties of the composites were then tested.

[0115] Before melt blending, the polymer matrix needs to be dried to remove moisture. Preferably, the polymer matrix can be placed in a vacuum oven at 70°C for 24 hours to remove moisture from the sample.

[0116] The process involves melt blending using a rheometer. Each blend system weighs 50g, and the ionic liquid content can be 2-10wt%, specifically 2wt%, 4wt%, 6wt%, 8wt%, or 10wt%, etc. The blending temperature is 200℃, the rotor speed is 120r / min, and the blending time is 10min. After blending, composite materials modified with ionic liquid IL, such as polyvinylidene fluoride, modified polyacrylonitrile, modified polyamide-imide, modified polyvinyl chloride, modified nylon 11, or modified perfluoroethylene-propylene copolymer, are obtained.

[0117] Taking polyvinylidene fluoride (PVDF) as an example, 1-butyl-3-methylimidazolium bromide was used as a modifier. Melt blending was performed using a rheometer. The blended system weighed 50g, with 8wt% 1-butyl-3-methylimidazolium bromide. The blending temperature was 200℃, the rotor speed was 120 r / min, and the blending time was 10 min. After blending, modified PVDF was obtained. The conductivity of the modified PVDF was tested to be 2.5 × 10⁻⁶. -14 Sm -1The conductivity of the modified polyvinylidene fluoride (PVDF) is increased by 10 orders of magnitude compared to pure PVDF. Pure PVDF has a dielectric constant of approximately 8.1 at 1000 Hz, while the modified PVDF has a dielectric constant of 65 at the same frequency, approximately eight times that of pure PVDF. This demonstrates that this modification can significantly improve the piezoelectric properties of the polymer matrix itself.

[0118] In the intelligent piezoelectric responsive polymer-based self-lubricating material provided by this invention, the piezoelectric polymer is preferably ionic liquid-modified vinylidene fluoride (IL-PVDF). IL-PVDF is a semi-crystalline polymer under normal conditions. Its applications are mainly concentrated in three major fields: petrochemicals, electronics, and coatings. IL-PVDF possesses excellent piezoelectricity, chemical resistance, processability, and resistance to fatigue and creep. IL-PVDF is renowned for its superior chemical stability, piezoelectricity, and electrical insulation properties, and is widely used in the semiconductor industry for storing and transporting high-purity chemicals. Products made from IL-PVDF resin, such as porous membranes, gels, and separators, are rapidly driving demand growth in the lithium-ion battery field, becoming one of the fastest-growing areas in the market. As a major raw material for fluorocarbon coatings, coatings made from IL-PVDF resin have evolved to the sixth generation. Due to their excellent weather resistance, they can be used outdoors for extended periods without maintenance and are widely used in power facilities, aviation facilities, transportation infrastructure, and high-rise buildings. In addition, IL-PVDF resin can be blended with other resins to improve performance. For example, composite materials made by blending with ABS resin have been widely used in fields such as construction, automotive interiors and household appliance housings.

[0119] The intelligent piezoelectric responsive polymer-based self-lubricating material provided by this invention comprises, by volume percentage: 1-10% piezoelectric powder and 90-99% piezoelectric polymer.

[0120] The intelligent piezoelectric responsive polymer-based self-lubricating material provided by the present invention comprises, by volume percentage: 1-10% piezoelectric powder and 90-99% piezoelectric polymer.

[0121] The piezoelectric powder is one of bismuth ferrite, bismuth tungstate, bismuth vanadate, or bismuth niobate.

[0122] The intelligent piezoelectric responsive polymer-based self-lubricating material provided by the present invention comprises, by volume percentage: 5% piezoelectric powder and 95% piezoelectric polymer.

[0123] The piezoelectric powder is bismuth ferrite, and the piezoelectric polymer is polyvinylidene fluoride.

[0124] The intelligent piezoelectric responsive polymer-based self-lubricating material provided by the present invention comprises, by volume percentage: 3-7% piezoelectric powder and 93-97% piezoelectric polymer.

[0125] The piezoelectric powder is one of bismuth ferrite, bismuth tungstate, bismuth vanadate, or bismuth niobate;

[0126] The piezoelectric polymer is a material modified by melt blending with alkylimidazolium ionic liquid as a modifier and polyvinylidene fluoride, polyacrylonitrile, polyamide-imide, polyvinyl chloride, nylon 11 or perfluoroethylene-propylene copolymer as a polymer matrix.

[0127] The intelligent piezoelectric responsive polymer-based self-lubricating material provided by the present invention comprises, by volume percentage: 5% piezoelectric powder and 95% piezoelectric polymer.

[0128] The piezoelectric powder is bismuth ferrite, and the piezoelectric polymer is polyvinylidene fluoride modified with alkyl imidazole ionic liquid.

[0129] The intelligent piezoelectric responsive polymer-based self-lubricating material provided by the present invention comprises, by volume percentage: 5% piezoelectric powder and 95% piezoelectric polymer.

[0130] The piezoelectric powders are bismuth ferrite / graphene oxide composites and bismuth ferrite / carbon nanotube composites, and the piezoelectric polymers are polyvinylidene fluoride modified with alkyl imidazole ionic liquids. Experiments have shown that using IL-PVDF with piezoelectric properties as the matrix and BiFeO3@CNTs or BiFeO3@GrO as piezoelectric powder fillers, the resulting intelligent piezoelectric responsive polymer-based self-lubricating material exhibits excellent wear resistance, piezoelectricity, self-lubrication, and high homogeneous charge characteristics.

[0131] Figure 3 This diagram illustrates the charge repulsion mechanism of the intelligent piezoelectric-responsive polymer-based self-lubricating material provided by this invention. Using a bismuth ferrite / carbon nanotube composite as the piezoelectric powder and polyvinylidene fluoride (PVDF) as the polymer matrix, the diagram shows that the intelligent piezoelectric-responsive polymer-based self-lubricating material, composed of bismuth ferrite / carbon nanotube composite (BiFeO2@CNTs) and polyvinylidene fluoride (PVDF), rubs against GCr15 steel. The shear force generated by friction causes mutual wear and tear on the surfaces of both the intelligent self-lubricating material and the steel. With increasing load, surface wear becomes more severe, and more material transfer occurs between the two materials. Furthermore, the frictional heating also causes some plastic molecular chains to break, leading to melting and plasticization. The breaking of molecular chains also generates a large number of free radicals, which promote charge transfer. Due to charge repulsion, like charges repel each other, reducing friction and wear, thus forming an intelligent self-lubricating effect.

[0132] Figure 4This invention provides a diagram illustrating the charge repulsion mechanism of a smart piezoelectric-responsive polymer-based self-lubricating material. The diagram uses a bismuth ferrite / carbon nanotube composite as the piezoelectric powder and polyvinylidene fluoride (PVDF) as the polymer matrix. As shown in the diagram, the smart piezoelectric-responsive polymer-based self-lubricating material exhibits negative triboelectricity, while the matrix (taking bearing steel as an example) exhibits positive triboelectricity. When neither material is in contact, both surfaces are uncharged. When an external force is applied directly above the generator, the bearing steel matrix moves downwards and comes into contact with the smart self-lubricating material. Electrons from the bearing steel matrix surface transfer to the smart self-lubricating material surface, making it negatively charged, while an equal amount of positive charge is distributed relative to the bearing steel matrix surface. When the bearing steel matrix and the smart self-lubricating material separate, the bottom bearing steel matrix generates a positive charge due to electrostatic induction, and electrons migrate from the bottom bearing steel matrix to the top bearing steel matrix through an external circuit. When the smart self-lubricating material and the bearing steel matrix are completely separated, the charges between the two bearing steel matrices reach equilibrium; at this point, there is no potential difference and no electron migration. This process then repeats. During the above process, a very thin transfer film is formed on the friction surface due to the material transfer at the material transfer point. At the same time, it fills the gap between the contact surfaces, reduces the coefficient of friction, and achieves an intelligent self-lubricating effect.

[0133] A second typical embodiment of the present invention provides a method for preparing the above-mentioned smart piezoelectric responsive polymer-based self-lubricating material, comprising:

[0134] Piezoelectric powder and piezoelectric polymer are mixed in a certain proportion to obtain a mixture, which is then molded to obtain a smart piezoelectric responsive polymer-based self-lubricating material.

[0135] In the preparation method provided by the present invention, the molding is compression molding or injection molding;

[0136] The compression molding process involves a molding pressure of 6–24 MPa and a molding temperature of 350–390 °C.

[0137] The molding process specifically includes the following steps: placing the mixture into a vulcanizing machine for sintering, then pressurizing and cooling the sintered mixture until it reaches room temperature to obtain a smart piezoelectric response polymer-based self-lubricating material.

[0138] The compression molding process uses pressures ranging from 6 to 24 MPa. Tests show that the pressure affects the final product performance of the smart piezoelectric-responsive polymer-based self-lubricating material. Insufficient pressure leads to excessive air bubbles within the compressed material, negatively impacting its piezoelectric and mechanical properties. Conversely, excessive pressure can cause the material to crack, affecting its usability.

[0139] The compression molding process utilizes temperatures ranging from 350 to 390°C. Tests show that temperature significantly impacts the final product quality of the smart piezoelectric-responsive polymer-based self-lubricating material. Excessive temperature can cause cracking during the compression process, rendering the material unusable. Conversely, insufficient temperature can lead to localized failure to form the material during compression.

[0140] A third typical embodiment of the present invention provides an application of the above-described intelligent piezoelectric responsive polymer-based self-lubricating material or the intelligent piezoelectric responsive polymer-based self-lubricating material prepared by the above-described preparation method in robots.

[0141] In the applications provided by this invention, intelligent piezoelectric responsive polymer-based self-lubricating materials are used in the moving joints of robots.

[0142] It should be noted that the intelligent piezoelectric responsive polymer-based self-lubricating material obtained after molding can be used directly, or it can be processed into the required shape before use. Preferably, the processing includes machining using an angle grinder, grinding wheel, or other devices.

[0143] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0144] Example 1

[0145] A smart piezoelectric responsive polymer-based self-lubricating material, by volume percentage, comprises: 5% bismuth ferrite nanoparticles and 95% polyvinylidene fluoride, and its preparation method is as follows:

[0146] According to the required molar mass fraction, with a Bi to Fe molar ratio of 1:1, bismuth ions (Bi) are provided to 500 mL of basic bismuth nitrate ([Bi6O6(OH)3](NO3)3·1.5H2O, 0.1 mol / L). 3+ ) and ferric sulfate (Fe2(SO4)3·7H2O, 0.1mol / L, providing iron ions Fe) 3+ Ammonia was added to the solution until bismuth and iron ions were completely precipitated. The mixture was then filtered with deionized water to remove all the precipitate. The filter was rinsed with deionized water. A small amount of ammonia (2M) and the filter were added to a 150 mL hydrothermal reactor, ensuring the total volume of all materials added did not exceed 1 / 3 of the total volume of the reactor lining. The mixture was stirred with a glass rod to ensure homogeneity, and the hydrothermal reaction was carried out (200℃, 24 h). After the reaction was complete, the mixture was filtered and dried at 70℃ for 4 h to obtain bismuth ferrite powder. The synthesized bismuth ferrite was then examined using a scanning electron microscope. Figure 5As shown, bismuth ferrite exhibits plate-like agglomerations, which are caused by the ferroelectric and ferromagnetic properties of bismuth ferrite.

[0147] Bismuth ferrite nanopowder and polyvinylidene fluoride were mixed in a certain proportion to obtain a mixture, which was then molded at a pressure of 15 MPa and a temperature of 370 °C to obtain a smart piezoelectric response polymer-based self-lubricating material.

[0148] Example 2

[0149] A smart piezoelectric responsive polymer-based self-lubricating material, by volume percentage, comprises: 5% bismuth ferrite nanoparticles and 95% ionic liquid-modified polyvinylidene fluoride, and its preparation method is as follows:

[0150] Using polyvinylidene fluoride (PVDF) as the polymer matrix and 1-butyl-3-methylimidazole bromide as the modifier, melt blending was performed using a rheometer. The blended system weighed 50 g, with 8 wt% 1-butyl-3-methylimidazole bromide. The blending temperature was 200 °C, the rotor speed was 120 r / min, and the blending time was 10 min. After blending, ionic liquid-modified PVDF was obtained. The conductivity of the modified PVDF was measured to be 2.5 × 10⁻⁶. -14 Sm -1 The conductivity of modified polyvinylidene fluoride (PVDF) is increased by 10 orders of magnitude compared to pure PVDF. The dielectric constant of pure PVDF is approximately 8.1 at 1000 Hz, while the dielectric constant of modified PVDF at the same frequency is increased to 65, which is about 8 times that of pure PVDF.

[0151] Bismuth ferrite nanopowder and ionic liquid-modified polyvinylidene fluoride were mixed in a certain proportion to obtain a mixture, which was then molded at a pressure of 15 MPa and a temperature of 370 °C to obtain a smart piezoelectric response polymer-based self-lubricating material.

[0152] Example 3

[0153] A smart piezoelectric-responsive polymer-based self-lubricating material, by volume percentage, comprises: 5% bismuth ferrite / graphene oxide composite nanoparticles and 95% ionic liquid-modified polyvinylidene fluoride, and its preparation method is as follows:

[0154] Using polyvinylidene fluoride (PVDF) as the polymer matrix and 1-butyl-3-methylimidazole bromide as the modifier, the mixture was melt-blended using a rheometer. The blended system weighed 50 g, with 1-butyl-3-methylimidazole bromide containing 8 wt%. The blending temperature was 200 °C, the rotor speed was 120 r / min, and the blending time was 10 min. After blending, ionic liquid-modified PVDF was obtained.

[0155] According to the required molar mass fraction, the molar ratio of Bi to Fe is 1:1. Take 500 mL of basic bismuth nitrate ([Bi6O6(OH)3](NO3)3·1.5H2O, 0.1 mol / L) to provide bismuth ions Bi. 3+ ) and ferric sulfate (Fe2(SO4)3·7H2O, 0.1mol / L, providing iron ions Fe) 3+ A solution of bismuth ferrite (BFeO3@GrO3) was prepared. Simultaneously, a certain amount of pre-prepared GO solution was added to the above solution. After ultrasonic vibration for 3 hours and mechanical stirring for 1 hour, a uniformly dispersed GO suspension was obtained. Ammonia water was added to the suspension until bismuth and iron ions were completely precipitated. The mixture was then filtered with deionized water to completely remove the precipitate. The filter material was rinsed with deionized water. A small amount of ammonia water (2M) and the filter material were added to a hydrothermal reactor, ensuring that the total volume of all materials added to the reactor did not exceed 1 / 3 of the total volume of the reactor lining. The mixture was stirred with a glass rod to ensure uniform mixing, and the hydrothermal reaction was carried out. The product was washed several times with deionized water and ethanol, and then placed in an 80℃ vacuum drying oven for 24 hours to finally obtain a bismuth ferrite / graphene oxide (BiFeO3@GrO3) composite material with a graphene oxide mass content of 5%.

[0156] Bismuth ferrite / graphene oxide composite nanopowder and ionic liquid-modified polyvinylidene fluoride were mixed in a certain proportion to obtain a mixture, which was then molded at a pressure of 15 MPa and a molding temperature of 370 °C to obtain a smart piezoelectric response polymer-based self-lubricating material.

[0157] Example 4

[0158] A smart piezoelectric responsive polymer-based self-lubricating material, by volume percentage, comprises: 5% bismuth ferrite / carbon nanotube composite nanopowder and 95% ionic liquid-modified polyvinylidene fluoride, and its preparation method is as follows:

[0159] Using polyvinylidene fluoride (PVDF) as the polymer matrix and 1-butyl-3-methylimidazole bromide as the modifier, the mixture was melt-blended using a rheometer. The blended system weighed 50 g, with 1-butyl-3-methylimidazole bromide containing 8 wt%. The blending temperature was 200 °C, the rotor speed was 120 r / min, and the blending time was 10 min. After blending, ionic liquid-modified PVDF was obtained.

[0160] According to the required molar mass fraction, the molar ratio of Bi to Fe is 1:1. Take 500 mL of basic bismuth nitrate ([Bi6O6(OH)3](NO3)3·1.5H2O, 0.1 mol / L) to provide bismuth ions Bi. 3+ ) and ferric sulfate (Fe2(SO4)3·7H2O, 0.1mol / L, providing iron ions Fe) 3+A solution of bismuth ferrite (BFeO3) and a certain amount of pre-prepared alkaline carbon nanotube solution were added to the above solution. After ultrasonic vibration for 3 hours and mechanical stirring for 1 hour, a suspension of CNTs with uniform dispersion was obtained. Ammonia water was added to the suspension until bismuth and iron ions in the suspension were completely precipitated. The mixture was filtered with deionized water to completely remove the precipitate. The filter was rinsed with deionized water. A small amount of ammonia water (2M) and the filter were added to the hydrothermal reactor to ensure that the total volume of all materials added to the reactor did not exceed 1 / 3 of the total volume of the reactor lining. The mixture was stirred with a glass rod to ensure uniform mixing of the materials in the reactor and to carry out the hydrothermal reaction. The product was washed several times with deionized water and ethanol and placed in a vacuum drying oven at 80℃ for 24 hours to finally obtain a bismuth ferrite / carbon nanotube (BiFeO3@CNTs) composite material with a carbon nanotube mass content of 5%.

[0161] Bismuth ferrite / graphene oxide composite nanopowder and ionic liquid-modified polyvinylidene fluoride were mixed in a certain proportion to obtain a mixture, which was then molded at a pressure of 15 MPa and a molding temperature of 370 °C to obtain a smart piezoelectric response polymer-based self-lubricating material.

[0162] Example 5

[0163] A smart piezoelectric responsive polymer-based self-lubricating material, by volume percentage, comprises: 5% bismuth tungstate nanoparticles and 95% polyvinylidene fluoride. The preparation method differs from that of Example 1 in that ferric sulfate is replaced with sodium tungstate dihydrate, while the remaining steps are the same as those of Example 1.

[0164] Example 6

[0165] A smart piezoelectric responsive polymer-based self-lubricating material, by volume percentage, comprises: 5% bismuth vanadate nanopowder and 95% polyvinylidene fluoride. The preparation method differs from that of Example 1 in that ferric sulfate is replaced with ammonium metavanadate, while the remaining steps are the same as those of Example 1.

[0166] Example 7

[0167] A smart piezoelectric responsive polymer-based self-lubricating material, by volume percentage, comprises: 5% bismuth niobate nanopowder and 95% polyvinylidene fluoride. The preparation method differs from that of Example 1 in that ferric sulfate is replaced with potassium hexaniobate, while the remaining steps are the same as those of Example 1.

[0168] Performance verification

[0169] The intelligent piezoelectric response polymer-based self-lubricating material obtained in the examples was cut according to the test requirements. Pin-On-Disc (POD) tribometers (Wazau, Germany) were used to conduct pin-on-disc tests. The materials were run at a speed of 0.05 m / s for 3 hours under pressures of 5 N, 10 N, and 20 N, respectively, and the friction coefficient and wear changes were detected.

[0170] from Figure 6 , Figure 7 As can be seen, with the increase of load, the friction coefficient and friction loss of the intelligent piezoelectric response polymer-based self-lubricating material provided in Embodiment 1 of the present invention are lower than those of pure PVDF. Furthermore, the changes in friction coefficient and friction loss between the blended materials show a trend of first decreasing and then increasing. This indicates that the intelligent piezoelectric response polymer-based self-lubricating material provided by the present invention has the functions of reducing friction coefficient, reducing friction loss, and extending the service life of robot joints.

[0171] The performance of the intelligent piezoelectric responsive polymer-based self-lubricating materials provided in Examples 2-4 of this invention is similar to that in Example 1. In both cases, the coefficient of friction first decreases and then increases with increasing load, and the friction loss also first decreases and then increases. Under 10N pressure, the order of minimum coefficient of friction from smallest to largest is: Example 3 = Example 4 < Example 2 < Example 1; the order of minimum friction loss from smallest to largest is: Example 3 = Example 4 < Example 2 < Example 1. Therefore, it can be seen that using IL-PVDF with piezoelectric properties as the matrix and BiFeO3@CNTs or BiFeO3@GrO as piezoelectric powder fillers, the resulting intelligent piezoelectric responsive polymer-based self-lubricating materials exhibit excellent wear resistance, piezoelectricity, self-lubrication, and high homogeneous charge characteristics.

[0172] The performance of the intelligent piezoelectric-responsive polymer-based self-lubricating materials provided in Examples 5-7 of this invention is similar to that in Example 1; the coefficient of friction of the material first decreases and then increases, and the friction loss also first decreases and then increases. Under a pressure of 10N, as... Figure 8 The examples shown are arranged from smallest to largest according to the minimum coefficient of friction, in the order of Example 5 < Example 7 < Example 6; Figure 9 The lowest frictional losses shown are arranged from smallest to largest as follows: Example 5 < Example 7 < Example 6.

[0173] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. Use of an intelligent piezoelectric responsive polymer-based self-lubricating material in a robot, characterized in that, The intelligent piezoelectric responsive polymer-based self-lubricating material comprises, by volume percentage: 1-5% piezoelectric powder and 95-99% piezoelectric polymer. The piezoelectric powder is selected from at least one of bismuth tungstate, bismuth vanadate, bismuth niobate, bismuth ferrite / graphene oxide composite, bismuth tungstate / graphene oxide composite, bismuth vanadate / graphene oxide composite, bismuth niobate / graphene oxide composite, bismuth ferrite / carbon nanotube composite, bismuth tungstate / carbon nanotube composite, bismuth vanadate / carbon nanotube composite and / or bismuth niobate / carbon nanotube composite. The piezoelectric polymer includes polyvinylidene fluoride and modified polyvinylidene fluoride; The modification involves using a conductive alkylimidazolium ionic liquid as a modifier and obtaining modified polyvinylidene fluoride through melt blending. The intelligent piezoelectric-responsive polymer-based self-lubricating material is used in the moving joints of robots.

2. Use according to claim 1, wherein The piezoelectric powder is a micro-nano-scale powder.

3. The use according to claim 1, wherein The alkylimidazolium ionic liquid is one of 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-butyl-3-methylimidazolium hydrogen sulfate.

4. Use according to any one of claims 1 to 3, wherein The intelligent piezoelectric responsive polymer-based self-lubricating material comprises, by volume percentage: 1-5% piezoelectric powder and 95-99% piezoelectric polymer. The piezoelectric powder is one of bismuth tungstate, bismuth vanadate, or bismuth niobate.

5. The use according to claim 4, wherein the compound is ###0002### The intelligent piezoelectric responsive polymer-based self-lubricating material comprises, by volume percentage: 5% piezoelectric powder and 95% piezoelectric polymer.

6. Use according to any one of claims 1 to 3, wherein The intelligent piezoelectric responsive polymer-based self-lubricating material comprises, by volume percentage: 5% piezoelectric powder and 95% piezoelectric polymer; the piezoelectric powder is bismuth ferrite, and the piezoelectric polymer is polyvinylidene fluoride modified with alkyl imidazole ionic liquid.

7. The use according to claim 1, wherein The preparation method of the intelligent piezoelectric responsive polymer-based self-lubricating material includes: Piezoelectric powder and piezoelectric polymer are mixed in a certain proportion to obtain a mixture, which is then molded to obtain a smart piezoelectric responsive polymer-based self-lubricating material.

8. Use according to claim 7, wherein the compound is ###0002### The molding process is either compression molding or injection molding. The compression molding process involves a molding pressure of 6-24 MPa and a molding temperature of 350-390℃.

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