Carbon brush composite material for unmanned aerial vehicle motor and preparation method thereof

Abstract

The invention discloses a carbon brush composite material for an unmanned aerial vehicle motor and a preparation method of the carbon brush composite material, and the carbon brush composite material is prepared from the following components in parts by weight: 65-80 parts of electrolytic copper powder, 20-40 parts of crystalline flake graphite powder, 3-9 parts of modified carbon fibers, 3-9 parts of modified graphene oxide, 10-25 parts of phenolic resin powder and 3-6 parts of molybdenum disulfide. According to the prepared carbon brush, through cooperative enhancement of multi-dimensional carbon components, high unification of high conductivity, excellent mechanical strength and wear resistance is achieved, commutation sparks and operation noise are effectively restrained through the unique microstructure in the carbon brush, energy loss is reduced, the working current of a motor is stable, the rectification characteristic is excellent, shock resistance and wear resistance are achieved, and the service life of the motor is prolonged. And the stability and the service life of the unmanned aerial vehicle motor under a high-speed working condition are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of carbon brush technology, specifically to a carbon brush composite material for drone motors and its preparation method. Background Technology

[0002] With the rapid development of drone technology, drones are increasingly used in military, civilian, and commercial fields, placing increasingly higher demands on the performance of their core power system—the motor. Drone motors need to operate stably for extended periods under harsh conditions such as high speed, high power density, and wide temperature ranges, while also meeting special requirements such as lightweight design, low noise, and high reliability. As a key component of brushed DC motors, the performance of carbon brushes directly affects the motor's efficiency, stability, and lifespan.

[0003] Traditional carbon brush materials primarily use graphite, carbon black, and resin as the matrix, with metal powder added to improve conductivity. However, these materials exhibit several problems under the high-speed, high-load conditions of drone motors: First, insufficient conductivity and high contact resistance lead to increased energy loss and reduced motor efficiency; second, low mechanical strength makes them prone to wear and breakage during high-speed rotation and frequent start-stop cycles, affecting motor stability; third, poor commutation performance easily generates arcs and sparks, reducing motor efficiency and potentially causing electromagnetic interference; and fourth, limited noise control capabilities, with the mechanical and electromagnetic noise generated during high-speed operation failing to meet the stealth requirements of drones.

[0004] In recent years, researchers have attempted to improve carbon brush performance by introducing novel carbon materials such as carbon fiber and graphene. While the addition of carbon fiber can increase the mechanical strength of the material, its poor dispersion in the matrix and tendency to agglomerate lead to unstable performance. Although graphene possesses excellent electrical conductivity, its application in composite materials presents challenges such as dispersion difficulties and weak interfacial bonding. Existing surface modification methods are mostly complex, costly, and have limited modification effects, making it difficult to meet the stringent requirements of drone motors for the comprehensive performance of carbon brush materials.

[0005] Therefore, developing a novel carbon brush composite material with high conductivity, excellent mechanical properties, good commutation characteristics, and noise reduction capabilities is of great significance for improving the overall performance of UAV motors. This requires systematic innovation in material composition design, surface modification technology, and manufacturing processes to overcome existing technological bottlenecks and meet the urgent needs of UAV motor development. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a carbon brush composite material for UAV motors and its preparation method. The carbon brush prepared by the present invention achieves a high degree of unity between high conductivity, excellent mechanical strength and wear resistance through the synergistic reinforcement of multi-dimensional carbon components. Its unique internal microstructure effectively suppresses commutation sparks and operating noise, reduces energy loss, and provides stable motor operating current, excellent rectification characteristics, shock resistance and wear resistance, significantly improving the stability and service life of UAV motors under high-speed conditions.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A carbon brush composite material for drone motors, by weight, is made of the following components: 65-80 parts electrolytic copper powder, 20-40 parts flake graphite powder, 3-9 parts modified carbon fiber, 3-9 parts modified graphene oxide, 10-25 parts phenolic resin powder, and 3-6 parts molybdenum disulfide.

[0009] Preferably, the modified graphene oxide is prepared by the following method steps:

[0010] Graphene oxide was added to deionized water and ultrasonically dispersed. Zinc nitrate hexahydrate and boric acid were added sequentially and stirred to dissolve. Ammonia was then added to adjust the pH. The mixture was transferred to an autoclave for hydrothermal reaction. The product was centrifuged, washed, and dried to obtain modified graphene oxide.

[0011] Preparation of modified graphene oxide: After graphene oxide is dispersed in water, zinc nitrate hexahydrate ionizes to produce... Boric acid ions are formed by partial ionization in water. Complex anions. When ammonia is added to adjust the pH to alkaline, it first forms... The precipitate precursor was then subjected to hydrothermal high temperature and high pressure conditions. It undergoes a complexation reaction with boric acid molecules: Zinc borate crystals are generated. The oxygen-containing functional groups (carboxyl, hydroxyl, and epoxy groups) on the surface of graphene oxide serve as nucleation sites, inducing zinc borate nanocrystals to grow in situ on their surface and bond firmly, forming a zinc borate / graphene oxide composite material.

[0012] Preferably, the ratio of graphene oxide, deionized water, zinc nitrate hexahydrate, and boric acid is 1g: 200~400mL: 0.6~1g: 0.08~0.14g.

[0013] Preferably, the mixture is ultrasonically dispersed for 1-2 hours; stirred for 30 minutes until dissolved; the pH of the system is adjusted to 8.5-9.5; and the hydrothermal reaction is carried out at 140-160℃ for 10-16 hours.

[0014] Preferably, the modified carbon fiber is prepared by the following method steps:

[0015] (1) Add carbon fiber to acetone for ultrasonic cleaning, then immerse it in concentrated nitric acid for activation, take it out, wash and dry it, then add it to an ethanol / water mixture, add glacial acetic acid to adjust the pH, add 3-mercaptopropyltrimethoxysilane, reflux reaction, filter, rinse and dry the product to obtain pretreated carbon fiber.

[0016] Carbon fiber pretreatment and thiolization: After acetone cleaning to remove oil stains from the carbon fiber surface, concentrated nitric acid undergoes a strong oxidation reaction at high temperature, introducing a large number of oxygen-containing functional groups onto the carbon fiber surface, increasing surface activity and hydrophilicity. Subsequently, under acidic conditions, 3-mercaptopropyltrimethoxysilane undergoes a hydrolysis reaction to generate silanol groups. Under reflux heating conditions, the silanol undergoes a condensation reaction with the hydroxyl groups on the carbon fiber surface, forming stable silicon-oxygen-carbon covalent bonds, achieving the chemical grafting of thiol groups onto the carbon fiber surface.

[0017] Preferably, in step (1), the ratio of carbon fiber, ethanol / water mixture, and 3-mercaptopropyltrimethoxysilane is 5g:100~300mL:2~5mL; the volume ratio of ethanol and deionized water in the ethanol / water mixture is 95~98:3~5.

[0018] Preferably, in step (1), ultrasonic cleaning is performed for 30 minutes; the concentration of concentrated nitric acid is 65~68wt%, and the activation conditions are reflux activation at 60~80℃ for 2~4 hours; the pH is adjusted to 4~5 with glacial acetic acid; and the reflux reaction conditions are reflux reaction at 65~80℃ for 6~9 hours.

[0019] (2) The pretreated carbon fiber was immersed in silver nitrate solution and stirred at room temperature in the dark. Then sodium borohydride solution was added dropwise for reduction reaction. The product was filtered, washed and dried to obtain modified carbon fiber.

[0020] In-situ loading of silver: The thiol groups on the pretreated carbon fiber surface have strong coordination ability and react with silver nitrate solution at room temperature. The ions undergo coordination complexation, and silver ions are anchored at the thiol sites. Subsequently, sodium borohydride, a strong reducing agent, is added, and a reduction reaction occurs, reducing the silver ions to silver atoms. Due to the anchoring effect of the thiol groups, silver atoms preferentially nucleate and aggregate at these active sites, forming uniformly dispersed silver nanoparticles. The thiol groups also act as stabilizers, preventing excessive aggregation of silver particles, ultimately yielding modified carbon fibers with uniformly loaded silver nanoparticles.

[0021] Preferably, in step (2), the ratio of the amount of pretreated carbon fiber, silver nitrate solution, and sodium borohydride solution is 5g: 200~300mL: 20~50mL; the 200~300mL silver nitrate solution contains 0.5~1g silver nitrate; and the 20~50mL sodium borohydride solution contains 0.1~0.3g sodium borohydride.

[0022] Preferably, in step (2), the stirring reaction conditions are 4-7 h at room temperature in the dark; the reduction reaction conditions are 1-2 h at 25-40°C.

[0023] The present invention also claims a method for preparing the carbon brush for a drone motor, comprising the following steps: weighing electrolytic copper powder, flake graphite powder, modified carbon fiber, modified graphene oxide, phenolic resin powder, and molybdenum disulfide in parts by weight, adding them to a mixer to mix, obtaining a mixed powder, pressing it to obtain a carbon brush blank, placing it in a crucible, and sintering it in a furnace at 1000~1400℃ to obtain the carbon brush for a drone motor.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The carbon brush composite material of this invention achieves excellent comprehensive performance through a carefully designed component ratio. Electrolytic copper powder, as the main conductive phase, provides excellent conductivity and current carrying capacity; flake graphite powder, with its unique layered structure, not only enhances the material's self-lubricating properties and reduces the friction coefficient with the commutator, but also constructs a continuous conductive path; modified carbon fiber, with its high strength and high modulus, significantly improves the mechanical strength and impact resistance of the carbon brush; modified graphene oxide, utilizing its ultra-large specific surface area and excellent conductivity, acts as a conductive bridge in the composite material, effectively reducing contact resistance; phenolic resin powder, as the organic binder phase, carbonizes during high-temperature sintering to form a carbonized network structure, significantly improving the product's mechanical strength and ensuring a strong bond between the components; molybdenum disulfide, as a solid lubricant, further improves friction and wear performance. The synergistic effect of these components makes the carbon brush performance more stable, significantly reduces current fluctuations, greatly improves motor operating stability and rectification characteristics, increases operating efficiency, and significantly reduces carbon brush wear rate.

[0026] 2. This invention provides a modified graphene oxide, wherein zinc borate nanocrystals are grown in situ on its surface via a hydrothermal method, and undergo a thermal decomposition reaction during high-temperature sintering. The volatilization process creates uniform open pores, acting as a pore-forming agent. These pores improve the arc discharge environment, reduce spark generation, and absorb sound waves generated during motor operation, effectively reducing noise. The residual ZnO nanoparticles, as a wide-bandgap semiconductor filling phase, significantly improve the hardness and wear resistance of graphene oxide, as well as its thermal and electrical stability at high temperatures. The oxygen-containing functional groups introduced through nitric acid oxidation in modified carbon fibers significantly enhance the chemical activity of the fiber surface and the interfacial bonding strength with the matrix. Thiol-based chemical grafting provides uniform anchoring points for silver nanoparticles, and the loading of silver nanoparticles further improves the fiber's conductivity and contact stability. The two-dimensional conductive network constructed by modified graphene oxide and the one-dimensional reinforcing skeleton provided by modified carbon fiber intertwine to form a continuous three-dimensional conductive pathway; the combined effect of ZnO nanoparticles and silver nanoparticles enables the composite material to maintain stable electrical contact performance under high current density conditions; the uniform pore structure formed by sintering not only improves the arc environment, but also significantly reduces operating noise, ultimately achieving a comprehensive improvement in the carbon brush material in terms of conductivity, mechanical properties, wear resistance, vibration reduction and noise reduction. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Of course, the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0028] Unless otherwise specified, all chemical reagents and materials in this invention are purchased from the market or synthesized from raw materials purchased from the market.

[0029] The graphene oxide sheets had a diameter of 50~100μm and a thickness of 0.8~1.2nm, and were purchased from Bailingwei Technology Co., Ltd.

[0030] Flake graphite powder has a mesh size of 325-500.

[0031] The carbon fiber has a particle size of -500 mesh and a bulk density of ≥2.12 g / cm³. 3 Tensile strength 7.0 GPa, resistivity ≤10 μΩ·m;

[0032] The phenolic resin powder was purchased from Jinan Baijin Chemical Technology Co., Ltd., and its mesh size is 300 mesh.

[0033] A method for preparing carbon brushes for drone motors includes the following steps:

[0034] (1) Add 1g of graphene oxide to 200-400mL of deionized water and disperse it by ultrasonication for 1-2h. Then add 0.6-1g of zinc nitrate hexahydrate and 0.08-0.14g of boric acid in sequence and stir for 30min until dissolved. Then add ammonia water to adjust the pH of the system to 8.5-9.5. Transfer it to an autoclave and hydrothermally react at 140-160℃ for 10-16h. Centrifuge, wash and dry the product to obtain modified graphene oxide.

[0035] (2) Add 5g of carbon fiber to 100~300mL of acetone and ultrasonically clean for 30min. Then immerse it in 65~68wt% concentrated nitric acid and reflux at 60~80℃ for 2~4h. Take it out, wash and dry it. Then add it to an ethanol / water mixture (ethanol and deionized water volume ratio of 95~98:3~5). Add glacial acetic acid to adjust the pH to 4~5. Add 2~5mL of 3-mercaptopropyltrimethoxysilane and reflux at 65~80℃ for 6~9h. Filter, rinse and dry the product to obtain pretreated carbon fiber.

[0036] (3) Soak 5g of pretreated carbon fiber in 200-300mL of silver nitrate solution containing 0.5-1g of silver nitrate, stir and react at room temperature in the dark for 4-7h, then add 20-50mL of sodium borohydride solution containing 0.1-0.3g of sodium borohydride, reduce and react at 25-40℃ for 1-2h, filter, wash and dry the product to obtain modified carbon fiber;

[0037] (4) Weigh 65-80 parts of electrolytic copper powder, 20-40 parts of flake graphite powder, 3-9 parts of modified carbon fiber, 3-9 parts of modified graphene oxide, 10-25 parts of phenolic resin powder, and 3-6 parts of molybdenum disulfide according to the weight ratio, add them to the mixer and mix to obtain mixed powder. Press the powder to obtain carbon brush blank, place it in a crucible, and sinter it in a furnace at 1000-1400℃ to obtain the carbon brush for the UAV motor.

[0038] The present invention will be further described below through specific embodiments.

[0039] Example 1

[0040] A method for preparing carbon brushes for drone motors includes the following steps:

[0041] (1) Add 1g of graphene oxide to 300mL of deionized water and disperse it by ultrasonication for 1.5h. Then add 1g of zinc nitrate hexahydrate and 0.14g of boric acid in sequence, stir for 30min until dissolved, then add ammonia water to adjust the pH of the system to 9.0, transfer to a high pressure vessel, and hydrothermally react at 160℃ for 10h. Centrifuge, wash and dry the product to obtain modified graphene oxide.

[0042] (2) Add 5g of carbon fiber to 200mL of acetone and ultrasonically clean for 30min. Then immerse it in 68wt% concentrated nitric acid and reflux at 80℃ for 2h. Take it out, wash and dry it. Then add it to an ethanol / water mixture (ethanol and deionized water volume ratio of 95:5). Add glacial acetic acid to adjust the pH to 4.5. Add 5mL of 3-mercaptopropyltrimethoxysilane and reflux at 80℃ for 6h. Filter, rinse and dry the product to obtain pretreated carbon fiber.

[0043] (3) 5g of pretreated carbon fiber was soaked in 300mL of silver nitrate solution containing 1g of silver nitrate and stirred at room temperature in the dark for 7h. Then, 50mL of sodium borohydride solution containing 0.3g of sodium borohydride was added dropwise and the reduction reaction was carried out at 40℃ for 1h. The product was filtered, washed and dried to obtain modified carbon fiber.

[0044] (4) Weigh 80g of electrolytic copper powder, 40g of flake graphite powder, 9g of modified carbon fiber, 9g of modified graphene oxide, 25g of phenolic resin powder and 6g of molybdenum disulfide according to the weight proportions, add them into a mixer and mix to obtain mixed powder. Press and form carbon brush blanks at 180MPa, place them in a crucible and sinter them in a furnace at 1200℃ to obtain the carbon brush for the UAV motor.

[0045] Example 2

[0046] A method for preparing carbon brushes for drone motors includes the following steps:

[0047] (1) 1g of graphene oxide was added to 300mL of deionized water and ultrasonically dispersed for 1.5h. Then, 0.9g of zinc nitrate hexahydrate and 0.12g of boric acid were added in sequence and stirred for 30min until dissolved. Then, ammonia water was added to adjust the pH of the system to 9.0. The mixture was transferred to an autoclave and hydrothermally reacted at 155℃ for 12h. The product was centrifuged, washed and dried to obtain modified graphene oxide.

[0048] (2) Add 5g of carbon fiber to 200mL of acetone and ultrasonically clean for 30min. Then immerse it in 68wt% concentrated nitric acid and reflux at 75℃ for 2h. Take it out, wash and dry it. Then add it to an ethanol / water mixture (ethanol and deionized water volume ratio of 95:5). Add glacial acetic acid to adjust the pH to 4.5. Add 4mL of 3-mercaptopropyltrimethoxysilane and reflux at 75℃ for 7h. Filter, rinse and dry the product to obtain pretreated carbon fiber.

[0049] (3) 5g of pretreated carbon fiber was soaked in 270mL of silver nitrate solution containing 0.8g of silver nitrate and stirred at room temperature in the dark for 6h. Then, 40mL of sodium borohydride solution containing 0.2g of sodium borohydride was added dropwise and the reduction reaction was carried out at 35℃ for 1.5h. The product was filtered, washed and dried to obtain modified carbon fiber.

[0050] (4) Weigh 75g of electrolytic copper powder, 35g of flake graphite powder, 7g of modified carbon fiber, 7g of modified graphene oxide, 20g of phenolic resin powder and 5g of molybdenum disulfide according to the weight proportions, add them to the mixer and mix to obtain mixed powder. Press and form carbon brush blanks at 180MPa, place them in a crucible and sinter them in a furnace at 1200℃ to obtain the carbon brush for the UAV motor.

[0051] Example 3

[0052] A method for preparing carbon brushes for drone motors includes the following steps:

[0053] (1) 1g of graphene oxide was added to 300mL of deionized water and ultrasonically dispersed for 1.5h. Then, 0.7g of zinc nitrate hexahydrate and 0.1g of boric acid were added in sequence and stirred for 30min until dissolved. Then, ammonia water was added to adjust the pH of the system to 9.0. The mixture was transferred to an autoclave and hydrothermally reacted at 145℃ for 14h. The product was centrifuged, washed and dried to obtain modified graphene oxide.

[0054] (2) Add 5g of carbon fiber to 200mL of acetone and ultrasonically clean for 30min. Then immerse it in 68wt% concentrated nitric acid and reflux at 65℃ for 3h. Take it out, wash and dry it. Then add it to an ethanol / water mixture (ethanol and deionized water volume ratio of 95:5). Add glacial acetic acid to adjust the pH to 4.5. Add 3mL of 3-mercaptopropyltrimethoxysilane and reflux at 70℃ for 8h. Filter, rinse and dry the product to obtain pretreated carbon fiber.

[0055] (3) 5g of pretreated carbon fiber was soaked in 240mL of silver nitrate solution containing 0.7g of silver nitrate and stirred at room temperature in the dark for 5h. Then, 30mL of sodium borohydride solution containing 0.2g of sodium borohydride was added dropwise and the reduction reaction was carried out at 30℃ for 1.5h. The product was filtered, washed and dried to obtain modified carbon fiber.

[0056] (4) Weigh 70g of electrolytic copper powder, 30g of flake graphite powder, 5g of modified carbon fiber, 5g of modified graphene oxide, 15g of phenolic resin powder and 4g of molybdenum disulfide according to the weight proportions, add them into a mixer and mix to obtain mixed powder. Press and form carbon brush blanks at 180MPa, place them in a crucible and sinter them in a furnace at 1200℃ to obtain the carbon brush for the UAV motor.

[0057] Example 4

[0058] A method for preparing carbon brushes for drone motors includes the following steps:

[0059] (1) 1g of graphene oxide was added to 300mL of deionized water and ultrasonically dispersed for 1.5h. Then, 0.6g of zinc nitrate hexahydrate and 0.08g of boric acid were added in sequence and stirred for 30min until dissolved. Then, ammonia water was added to adjust the pH of the system to 9.0. The mixture was transferred to an autoclave and hydrothermally reacted at 140℃ for 16h. The product was centrifuged, washed and dried to obtain modified graphene oxide.

[0060] (2) Add 5g of carbon fiber to 200mL of acetone and ultrasonically clean for 30min. Then immerse it in 68wt% concentrated nitric acid and reflux at 60℃ for 4h. Take it out, wash and dry it. Then add it to an ethanol / water mixture (ethanol and deionized water volume ratio of 95:5). Add glacial acetic acid to adjust the pH to 4.5. Add 2mL of 3-mercaptopropyltrimethoxysilane and reflux at 65℃ for 9h. Filter, rinse and dry the product to obtain pretreated carbon fiber.

[0061] (3) 5g of pretreated carbon fiber was soaked in 200mL of silver nitrate solution containing 0.5g of silver nitrate and stirred at room temperature in the dark for 4h. Then, 20mL of sodium borohydride solution containing 0.1g of sodium borohydride was added dropwise and the reduction reaction was carried out at 25℃ for 2h. The product was filtered, washed and dried to obtain modified carbon fiber.

[0062] (4) Weigh 65g of electrolytic copper powder, 20g of flake graphite powder, 3g of modified carbon fiber, 3g of modified graphene oxide, 10g of phenolic resin powder and 3g of molybdenum disulfide according to the weight proportions, add them into a mixer and mix to obtain mixed powder. Press and form carbon brush blanks at 180MPa, place them in a crucible and sinter them in a furnace at 1200℃ to obtain the carbon brush for the UAV motor.

[0063] Comparative Example 1

[0064] A method for preparing carbon brushes for drone motors includes the following steps:

[0065] (1) Add 5g of carbon fiber to 200mL of acetone and ultrasonically clean for 30min. Then immerse it in 68wt% concentrated nitric acid and reflux at 80℃ for 2h. Take it out, wash and dry it. Then add it to an ethanol / water mixture (ethanol and deionized water volume ratio of 95:5). Add glacial acetic acid to adjust the pH to 4.5. Add 5mL of 3-mercaptopropyltrimethoxysilane and reflux at 80℃ for 6h. Filter, rinse and dry the product to obtain pretreated carbon fiber.

[0066] (2) 5g of pretreated carbon fiber was soaked in 300mL of silver nitrate solution containing 1g of silver nitrate and stirred at room temperature in the dark for 7h. Then, 50mL of sodium borohydride solution containing 0.3g of sodium borohydride was added dropwise and the reduction reaction was carried out at 40℃ for 1h. The product was filtered, washed and dried to obtain modified carbon fiber.

[0067] (3) Weigh 80g of electrolytic copper powder, 40g of flake graphite powder, 9g of modified carbon fiber, 9g of graphene oxide, 25g of phenolic resin powder and 6g of molybdenum disulfide according to the weight proportions, add them into a mixer and mix to obtain mixed powder. Press and form carbon brush blanks at 180MPa, place them in a crucible and sinter them in a furnace at 1200℃ to obtain the carbon brush for the UAV motor.

[0068] Comparative Example 2

[0069] A method for preparing carbon brushes for drone motors includes the following steps:

[0070] (1) Add 1g of graphene oxide to 300mL of deionized water and disperse it by ultrasonication for 1.5h. Then add 1g of zinc nitrate hexahydrate and 0.14g of boric acid in sequence, stir for 30min until dissolved, then add ammonia water to adjust the pH of the system to 9.0, transfer to a high pressure vessel, and hydrothermally react at 160℃ for 10h. Centrifuge, wash and dry the product to obtain modified graphene oxide.

[0071] (2) Add 5g of carbon fiber to 200mL of acetone and ultrasonically clean for 30min. Then immerse it in 68wt% concentrated nitric acid and reflux at 80℃ for 2h. Take it out, wash and dry it. Then add it to an ethanol / water mixture (ethanol and deionized water volume ratio of 95:5). Add glacial acetic acid to adjust the pH to 4.5. Add 5mL of 3-mercaptopropyltrimethoxysilane and reflux at 80℃ for 6h. Filter, rinse and dry the product to obtain pretreated carbon fiber.

[0072] (3) Weigh 80g of electrolytic copper powder, 40g of flake graphite powder, 9g of pretreated carbon fiber, 9g of modified graphene oxide, 25g of phenolic resin powder and 6g of molybdenum disulfide according to the weight proportions, add them to the mixer and mix to obtain mixed powder. Press and form carbon brush blanks at 180MPa, place them in a crucible and sinter them in a furnace at 1200℃ to obtain the carbon brush for the UAV motor.

[0073] The carbon brushes prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to performance tests. Resistivity was tested according to JB / T 8133.2-2013 "Test Methods for Physicochemical Properties of Electro-Carbonized Products Part 2: Resistivity"; Rockwell hardness was tested according to JB / T 8133.3-2013 "Test Methods for Physicochemical Properties of Electro-Carbonized Products Part 3: Rockwell Hardness"; flexural strength was tested according to JB / T 8133.7-2013 "Test Methods for Physicochemical Properties of Electro-Carbonized Products Part 7: Flexural Strength"; and porosity was tested according to JB / T 8133.15-2013 "Test Methods for Physicochemical Properties of Electro-Carbonized Products Part 15: Porosity". The carbon brushes were then installed in the motor of a drone, and the noise level during motor operation was tested in a noise chamber, referring to GB / T The test was conducted according to 10069.1-2006 "Methods and Limits for the Measurement of Noise from Rotating Electrical Machines - Part 1: Methods for the Measurement of Noise from Rotating Electrical Machines". The distance between the motor and the test equipment was 75 cm. Five samples were repeated for each test, and the average value was taken. The test involved rubbing the motor rotor against the carbon brush, with a current density of 67 A / cm² passing through the carbon brush. 2 The contact pressure was 0.23 MPa, the rotor rotation speed was 1000 r / min, and after 100 hours of continuous grinding, the wear of the carbon brush length was measured and recorded as the wear rate. The carbon brush finished product was tested according to the air-cooled test method, with a working voltage of 12V, working time of 1.5s, rest time of 28.5s, and the power reduction of the carbon brush after 100,000 cycles was detected. The specific data are shown in Table 1.

[0074] Table 1. Carbon brush performance test results

[0075] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Resistivity (µΩ·m) 0.27 0.24 0.23 0.21 0.42 0.86 Rockwell hardness (HR10 / 392) 86 84 83 81 75 78 Flexural strength (MPa) 21.3 20.8 20.5 20.1 18.2 18.7 Open porosity (%) 14.3 13.9 13.7 13.5 9.6 13.1 Average noise (dB) 28 29 29 31 43 37 Wear rate (mm / 100h) 0.18 0.20 0.21 0.24 0.31 0.27 Power decrease (%) 8.1 8.3 8.3 8.6 14.4 11.7

[0076] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A carbon brush composite material for a drone motor, characterized by, The components are prepared by weight parts: electrolytic copper powder 65~80 parts, flake graphite powder 20~40 parts, modified carbon fiber 3~9 parts, modified graphene oxide 3~9 parts, phenolic resin powder 10~25 parts, and molybdenum disulfide 3~6 parts.

2. The carbon brush composite material for drone motor according to claim 1, characterized in that, The modified graphene oxide is prepared by the following method steps: The graphene oxide is added to deionized water, ultrasonic dispersion, and then zinc nitrate hexahydrate and boric acid are added in sequence, stirring and dissolving, followed by adding ammonia water to adjust the pH, and then transferring to an autoclave for hydrothermal reaction, centrifugation, washing and drying to obtain the modified graphene oxide.

3. The carbon brush composite material for drone motor according to claim 2, characterized in that, The amount ratio of graphene oxide, deionized water, zinc nitrate hexahydrate and boric acid is 1g:200~400mL:0.6~1g:0.08~0.14g.

4. The carbon brush composite material for drone motor according to claim 2, characterized in that, Ultrasonic dispersion for 1~2h; stirring for 30min to dissolve; adjust the pH of the system to 8.5~9.5; the hydrothermal reaction conditions are 140~160℃ for 10~16h.

5. The carbon brush composite material for drone motor according to claim 1, wherein The modified carbon fiber is prepared by the following method steps: (1) The carbon fiber is added to acetone for ultrasonic cleaning, then immersed in concentrated nitric acid for activation, washed and dried, and then added to an ethanol / water mixture, and the pH is adjusted by adding glacial acetic acid, and 3-mercaptopropyl trimethoxysilane is added, and refluxed to obtain the pretreated carbon fiber. (2) The pretreated carbon fiber is immersed in silver nitrate solution, and stirred at room temperature in the dark, then sodium borohydride solution is added dropwise, and the product is filtered, washed and dried to obtain the modified carbon fiber.

6. The carbon brush composite material for drone motor according to claim 5, characterized in that, In step (1), the amount ratio of carbon fiber, ethanol / water mixture and 3-mercaptopropyl trimethoxysilane is 5g:100~300mL:2~5mL; the volume ratio of ethanol to deionized water in the ethanol / water mixture is 95~98:3~5.

7. The carbon brush composite material for drone motor according to claim 5, characterized in that, In step (1), ultrasonic cleaning for 30min; the concentration of concentrated nitric acid is 65~68wt%, and the activation conditions are refluxing at 60~80℃ for 2~4h; the pH is adjusted to 4~5 with glacial acetic acid; the refluxing reaction conditions are refluxing at 65~80℃ for 6~9h.

8. The carbon brush composite material for drone motor according to claim 5, characterized in that, In step (2), the amount ratio of pretreated carbon fiber, silver nitrate solution and sodium borohydride solution is 5g:200~300mL:20~50mL; the 200~300mL silver nitrate solution contains 0.5~1g silver nitrate; the 20~50mL sodium borohydride solution contains 0.1~0.3g sodium borohydride.

9. The carbon brush composite material for drone motor according to claim 5, characterized in that, In step (2), the stirring reaction conditions are stirring at room temperature in the dark for 4~7h; the reduction reaction conditions are reduction at 25~40℃ for 1~2h.

10. A method of manufacturing the carbon brush for the motor of the drone according to any one of claims 1 to 9, characterized in that, The following steps are included: electrolytic copper powder, flake graphite powder, modified carbon fiber, modified graphene oxide, phenolic resin powder, and molybdenum disulfide are weighed by weight parts, added to a mixer, mixed to obtain a mixed powder, and pressed to obtain a carbon brush blank, which is placed in a crucible and sintered in a furnace at 1000~1400℃ to obtain the carbon brush for unmanned aerial vehicle motors.